JP6803673B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of such properties, the adhesive is preferably used in the form of an adhesive sheet for fixing parts in portable electronic devices such as mobile phones, smartphones, and tablet personal computers. It is also preferably used as an adhesive sheet that is re-peeled after being attached. Patent documents 1 and 2 are examples of documents disclosing this type of prior art. Both Patent Documents 1 and 2 disclose prior art relating to an stretchable adhesive sheet.

Japanese Unexamined Patent Publication No. 2016-8288 Special Table 2011-514419

The adhesive sheet is required to exhibit an adhesive force equal to or higher than a predetermined value in order to prevent adhesion defects such as peeling and misalignment during the period of use. On the other hand, the adhesive sheet attached to the adherend can be removed from the adherend after the purpose of use such as fixing is completed. For example, an adhesive sheet used as a means for fixing a component of a portable electronic device can be removed from an adherend when the member is repaired, replaced, inspected, recycled, or the like. When removing the adhesive sheet from the adherend, it is desirable that the removal work is completed without deforming or damaging the adherend regardless of the strength of the adherend. As one of the means, Patent Documents 1 and 2 disclose a method of using an stretchable adhesive sheet. In this method, a part of the adhesive sheet attached to the adherend is grasped and pulled, and the adhesive sheet is stretched and deformed to reduce the adhesive area, thereby removing the adhesive sheet from the adherend. In consideration of removal workability, such an adhesive sheet preferably has a small peeling stress at the time of removal.

Therefore, an object of the present invention is to provide an extensible adhesive sheet that exhibits a sufficient adhesive function when used and is excellent in tensile removability at the time of removal.

According to the present invention, an stretchable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is provided. This stretchable adhesive sheet (hereinafter, may be abbreviated as "adhesive sheet") has a total thickness of 150 μm or less. The pressure-sensitive adhesive sheet has an initial adhesive force A to polycarbonate of 2N / 20 mm or more and a tensile peeling stress B to polycarbonate of 16 N / 20 mm or less. The pressure-sensitive adhesive sheet according to a preferred embodiment includes a pressure-sensitive adhesive layer and a film-like base material that supports the pressure-sensitive adhesive layer.

When the initial adhesive strength A is equal to or higher than a predetermined value, a sufficient adhesive function can be exhibited on an adherend formed of various materials such as polycarbonate (PC). Further, when the tensile peeling stress B is equal to or less than a predetermined value, the direction of action in the 0 degree direction (shearing direction) with respect to the adhesive surface (typically −90 degrees to +90 degrees with respect to the adhesive surface). Direction. Hereinafter, the pressure-sensitive adhesive sheet can be smoothly removed from various adherends by pulling and stretching the pressure-sensitive adhesive sheet in the "tensile peeling direction"). Further, since the tensile peeling stress B is suppressed to a predetermined value or less, even if the total thickness of the adhesive sheet is limited to a predetermined value or less, the adhesive sheet is damaged (such as torn) at the time of tensile removal. Hateful. In short, according to the present invention, there is provided an adhesive sheet having a total thickness of a predetermined value or less, which has both a sufficient adhesive function at the time of use and excellent tensile removability at the time of removal.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the tensile peeling stress B [N / 20 mm] can be 2.0 times or less the initial pressure-sensitive adhesive force A [N / 20 mm]. That is, the ratio (B / A) of the tensile peeling stress B to the initial adhesive force A can be 2.0 or less. The small ratio (B / A) means that the tensile peeling stress B is reduced in relation to the initial adhesive force A. With such a configuration, it is possible to preferably achieve both a sufficient adhesive function at the time of use and excellent tensile removability at the time of removal.

In the pressure-sensitive adhesive sheet according to a preferred embodiment, the 300% elongation stress S _{300 of the} film-like substrate is 5 MPa or less. The pressure-sensitive adhesive sheet provided with the film-like base material having a low S ₃₀₀ can be significantly stretched and deformed with low stress, and the bonding area can be reduced. Therefore, according to the film-like base material, an extensible pressure-sensitive adhesive sheet having a low tensile peeling stress B can be preferably realized.

In the pressure-sensitive adhesive sheet according to another preferred embodiment, the 300% elongation stress S ₃₀₀ of the film-like substrate is 1.5 times or less the 100% elongation stress S ₁₀₀ of the film-like substrate. That is, S ₃₀₀ / S ₁₀₀ is 1.5 or less. The pressure-sensitive adhesive sheet provided with such a film-like base material can be significantly stretched and deformed to reduce the adhesive area while suppressing an increase in stretch stress due to an increase in the degree of stretch. Therefore, according to the film-like base material, an extensible pressure-sensitive adhesive sheet having a low tensile peeling stress B can be preferably realized.

As the film-like substrate, a film having a thickness of 10 μm or more and 90 μm or less can be preferably adopted. The pressure-sensitive adhesive sheet disclosed herein can be suitably realized by using a film-like substrate having a thickness in the above range.

The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in a manner in which the pressure-sensitive adhesive layer contains filler particles. By including the filler particles in the pressure-sensitive adhesive layer, the filler particles can contribute to the reduction of the tensile stress B when the pressure-sensitive adhesive sheet is stretched and deformed. As a result, an adhesive sheet that maintains both the initial adhesive force A and reduces the tensile peeling stress B can be preferably realized.

In a preferred embodiment, the average particle size of the filler particles can be greater than 3% and less than 50% of the thickness of the pressure-sensitive adhesive layer. According to the filler particles having the above average particle size in relation to the thickness of the pressure-sensitive adhesive layer, the tensile peeling stress B can be preferably reduced, and the maintenance of the initial adhesive force A and the reduction of the tensile peeling stress B are better compatible. Adhesive sheets can be realized.

In another preferred embodiment, the content of the filler particles in the pressure-sensitive adhesive layer can be 12 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the base polymer. By setting the content of the filler particles in the above range, the tensile peeling stress B can be effectively reduced while suppressing the decrease in the initial adhesive force A.

The pressure-sensitive adhesive sheet according to a preferred embodiment has, as the pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer provided on the first surface of the film-like base material and a second pressure-sensitive adhesive layer provided on the second surface of the film-like base material. A pressure-sensitive adhesive layer is provided. Such a double-sided pressure-sensitive adhesive sheet with a base material can be preferably used as a highly reliable fixing means (typically, a means for joining one object and another object).

In a preferred embodiment of the pressure-sensitive adhesive sheet provided by this specification, the pressure-sensitive adhesive sheet is preferably used for joining one object to another. The pressure-sensitive adhesive sheet can be stretched by pulling one end of the pressure-sensitive adhesive sheet in a state where the one object and the other object are bonded to each other with the pressure-sensitive adhesive sheet sandwiched between them. The state of bonding between one object and the other object can be released. Therefore, the bonding between the one object and the other object is a removable bonding. The above-mentioned one object and the above-mentioned other object may be different parts in one article or one member.

The pressure-sensitive adhesive sheet disclosed herein is preferably used for portable electronic devices. In particular, the pressure-sensitive adhesive sheet disclosed herein exhibits a sufficient adhesive function at the time of use and is excellent in tensile removability at the time of removal. Taking advantage of this feature, it is particularly preferably used as an adhesive sheet for fixing batteries, which is often removed when repairing or replacing members constituting a product, product inspection, or the like. According to the techniques disclosed herein, an adhesive sheet preferably used for fixing a battery is provided.

It is sectional drawing which shows typically one structural example of an adhesive sheet. It is explanatory drawing which shows typically the method of measuring the tensile peeling stress B. It is explanatory drawing which shows typically the method of measuring the shear adhesive force. 4 (a), 4 (b) and 4 (c) are schematic side views for explaining one aspect of tensile removal. 5 (a), 5 (b) and 5 (c) are schematic top views for explaining one aspect of tensile removal.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings regarding the implementation of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. In the following drawings, members / parts that perform the same action may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are modeled for clearly explaining the present invention, and do not necessarily accurately represent the size and scale of the adhesive sheet of the present invention actually provided as a product. ..

As described above, the term "adhesive" as used herein refers to a material that exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature and has the property of adhering to an adherend by pressure. The pressure-sensitive adhesive referred to here is generally a complex tensile modulus E ^* (1 Hz), as defined in, for example, "CA Dahlquist," Adhesion: Fundamental and Practice ", McLaren & Sons, (1966) P. 143". <material having a property that meets the ¹⁰ 7 dyne / cm ² (typically, a material having the properties in 25 ° C.) may be.

<Structure of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein is typically a base-based pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one surface (preferably both sides) of a film-like base material (support). The concept of an adhesive sheet here may include what is called an adhesive tape, an adhesive label, an adhesive film, or the like. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or in the form of a single leaf. Alternatively, it may be an adhesive sheet in a form further processed into various shapes. The film-like base material may not be used.

The pressure-sensitive adhesive sheet disclosed herein may have, for example, the cross-sectional structure schematically shown in FIG. The pressure-sensitive adhesive sheet 1 shown in FIG. 1 has pressure-sensitive adhesive layers 21 and 22 on each surface (both non-peelable) of the film-like base material 10. The pressure-sensitive adhesive sheet 1 before use has a structure in which each surface (each pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layers 21 and 22 is protected by a release liner (not shown). Alternatively, although not particularly shown, the pressure-sensitive adhesive sheet disclosed herein may be a base-less double-sided pressure-sensitive adhesive sheet consisting of only a pressure-sensitive adhesive layer.

As the release liner, a conventional release paper or the like can be used, and the release liner is not particularly limited. For example, it is made of a release liner having a release treatment layer on the surface of a liner base material such as a resin film or paper, or a low adhesive material of a fluoropolymer (polytetrafluoroethylene, etc.) or a polyolefin resin (polyethylene, polypropylene, etc.). A release liner or the like can be used. The peeling treatment layer may be formed by surface-treating the liner base material with a peeling treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

The pressure-sensitive adhesive sheet disclosed herein preferably has an elongated portion from the viewpoint of tensile removability. Thereby, in the adhesive sheet attached to the adherend, the adhesive sheet can be preferably removed from the adherend by grasping and pulling one end of the elongated portion in the longitudinal direction. The shape of the elongated portion is typically strip-shaped. From the viewpoint of tensile removability, the elongated portion may have a shape that tapers toward one end in the longitudinal direction. In a more preferred embodiment, the adhesive sheet is formed in an elongated shape as a whole. From the viewpoint of tensile removal workability, it is preferable that a tab (grip portion) is provided at one end of the pressure-sensitive adhesive sheet in the longitudinal direction. The shape of the tab is not particularly limited, but it is preferably a shape that can be gripped by a finger (for example, a rectangular shape).

<Characteristics of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein preferably has an initial adhesive strength A of 2N / 20 mm or more with respect to polycarbonate (PC). As a result, a sufficient adhesive function can be preferably exhibited with respect to the adherend formed from various materials such as PC. Further, when the pressure-sensitive adhesive sheet having the initial adhesive strength A is applied to, for example, a portable electronic device, the fixed arrangement of the adherend member can be maintained even when the portable electronic device is dropped. The initial adhesive strength A is more preferably 3N / 20 mm or more (more preferably 4N / 20 mm or more, for example, 5N / 20 mm or more). In a preferred embodiment, the initial adhesive strength A can be 6N / 20mm or higher (further 7N / 20mm or higher). The upper limit of the initial adhesive strength A is not particularly limited. From the viewpoint of tensile removability and adhesive residue prevention property, it is usually appropriate to set the initial adhesive force A to less than 20 N / 20 mm, and it is less than 15 N / 20 mm (more preferably less than 12 N / 20 mm, for example, less than 10 N / 20 mm. ) Is preferable.

The initial adhesive strength A can be measured by the following method. Prepare an adhesive sheet cut to a size of 20 mm in width and 100 mm in length. In an environment of 23 ° C. and 50% RH, the adhesive surface of the adhesive sheet (typically a double-sided adhesive sheet) is exposed, and the adhesive surface is pressure-bonded to the surface of the PC plate by reciprocating a 2 kg roller once. To do. After leaving this in the same environment for 30 minutes, using a tensile tester, the peel strength [N / 20 mm width] under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees according to JIS Z 0237: 2000. To measure. When the adhesive sheet is a double-sided adhesive sheet, a polyethylene terephthalate (PET) film having a thickness of 25 μm may be attached to the other adhesive surface, and then the adhesive surface to be measured may be pressure-bonded to a PC plate for measurement. As the tensile tester, a universal tensile compression tester (product name "TG-1kN", manufactured by Minebea) can be used. The same method is adopted for the examples described later.

The pressure-sensitive adhesive sheet disclosed here preferably has a tensile peeling stress B with respect to a PC of 16 N / 20 mm or less. Thereby, when the adhesive sheet is pulled from the adherend in the tensile peeling direction, the adhesive sheet can be removed from the adherend more smoothly. The tensile peeling stress B is more preferably 15 N / 20 mm or less (more preferably 14 N / 20 mm or less, for example 13 N / 20 mm or less). In a preferred embodiment, the tensile peel stress B can be 12N / 20mm or less (and even 11N / 20mm or less). The lower limit of the tensile peeling stress B is not particularly limited. From the relationship with the initial adhesive force A, it is usually appropriate that the tensile peeling stress B is 3N / 20 mm or more (typically 5N / 20 mm or more, for example, 7N / 20 mm or more).

The tensile peeling stress B can be measured by the following method. A measurement sample is prepared by cutting the adhesive sheet into a size of 20 mm in width and 120 mm in length. In an environment of 23 ° C. and 50% RH, each adhesive surface of the above measurement sample (typically a double-sided adhesive sheet) is overlapped on the surface of two PC plates (30 mm × 100 mm × 2 mm thickness) to obtain 2 kg. The roller is reciprocated once and crimped. 70 mm (that is, 20 mm × 70 mm) from one end of the measurement sample in the longitudinal direction is crimped to each PC plate. After leaving this in the same environment for 30 minutes, two PC plates were fixed to each other using a tensile tester, and the peel strength [N / 20 mm width] was obtained under the conditions of a tensile speed of 300 mm / min and a peeling angle of 0 degrees. ] Is measured. Specifically, as shown in FIG. 2, the adhesive surfaces 100A and 100B of the measurement sample 100 are bonded to and pressure-bonded to the two PC plates 111 and 112, respectively. This is pulled in the direction of the arrow in FIG. 2 (that is, the tensile peeling direction) at the above speed, and the peeling strength [N / 20 mm width] is measured. In the case of a single-sided adhesive sheet (single-sided adhesive sheet), the peel strength [N / 20 mm width] may be measured in the same manner as above except that one adhesive surface is fixed to one PC plate. As the tensile tester, a universal tensile compression tester (product name "TG-1kN", manufactured by Minebea) can be used. The same method is adopted for the examples described later.

The pressure-sensitive adhesive sheet disclosed herein preferably has a ratio (B / A) of the tensile peeling stress B [N / 20 mm] to the initial pressure-sensitive adhesive force A [N / 20 mm] of about 3.0 or less. As a result, it is possible to preferably achieve both a sufficient adhesive function at the time of use and excellent tensile removability at the time of removal. In one aspect, the ratio (B / A) can be, for example, less than about 2.5 (more preferably about 2.4 or less, still more preferably about 2.2 or less). In the pressure-sensitive adhesive sheet according to a preferred embodiment, the ratio (B / A) is about 2.0 or less (more preferably about 1.8 or less, still more preferably about 1.6 or less, for example, about 1.5 or less). possible. Ideally, the lower the ratio (B / A), the better, but in practice, for example, it may be about 0.8 or more, or may be about 1.0 or more.

It is usually appropriate that the pressure-sensitive adhesive sheet disclosed here exhibits a breaking strength of about 3 MPa or more. As a result, for example, in a configuration exhibiting an adhesive strength of a predetermined value or higher, damage such as tearing is less likely to occur when the adhesive sheet is removed. In a preferred embodiment, the breaking strength may be about 5 MPa or more (for example, about 6 MPa or more), and further may be about 7 MPa or more (for example, about 8 MPa or more). The upper limit of breaking strength is not particularly limited. Usually, from the viewpoint of elasticity and extensibility of the pressure-sensitive adhesive sheet, the breaking strength is usually preferably about 100 MPa or less, and preferably about 80 MPa or less (for example, about 70 MPa or less). Further, since the pressure-sensitive adhesive sheet disclosed herein can be tensile-peeled even by a low stress, it is preferably carried out even in an embodiment in which the breaking strength of the pressure-sensitive adhesive sheet is about 30 MPa or less (further, about 20 MPa or less, for example, about 15 MPa or less). Can be done.

The breaking strength is measured according to the method for measuring "tensile strength" described in JIS K 7311: 1995. More specifically, the breaking strength can be measured under the condition of a tensile speed of 300 mm / min using a No. 3 dumbbell-shaped test piece (width 5 mm). As the tensile tester, the product name "Autograph AG-10G type tensile tester" manufactured by Shimadzu Corporation can be used. In the test, it is preferable to sprinkle powder on the adhesive surface to remove the influence of the stickiness of the adhesive. The tensile direction in the above test is not particularly limited, but when the adhesive sheet has a long shape, it is preferable to match the tensile direction with the longitudinal direction thereof. The breaking strength can be adjusted, for example, by selecting the base material type (selecting the blending ratio of the hard component and the soft component, etc.).

The pressure-sensitive adhesive sheet disclosed herein preferably exhibits an elongation at break of approximately 300% or more. As a result, the tension and the elongation and deformation of the pressure-sensitive adhesive sheet interact with each other, and excellent tensile removal property is realized. The elongation at break is more preferably about 400% or more (for example, about 450% or more, typically about 500% or more). The upper limit of the elongation at break is not particularly limited. From the viewpoint of workability for removing the pressure-sensitive adhesive sheet, the elongation at break may be, for example, about 1500% or less, or about 1200% or less.

The elongation at break is measured according to the "elongation" measuring method described in JIS K 7311: 1995. More specifically, the elongation at break can be measured under the condition of a tensile speed of 300 mm / min using a No. 3 dumbbell-shaped test piece (width 5 mm, marked line spacing 20 mm). The tensile tester and others are basically the same as in the case of the breaking strength described above. The tensile direction in the above test is not particularly limited, but when the adhesive sheet has a long shape, it is preferable to match the tensile direction with the longitudinal direction thereof. The elongation at break can be adjusted, for example, by selecting the base material type.

The 300% elongation stress A ₃₀₀ of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, but it is usually appropriate that it is less than about 10 MPa (for example, about 7 MPa or less). In the pressure-sensitive adhesive sheet according to a preferred embodiment, the 300% elongation stress A ₃₀₀ can be about 5 MPa or less (for example, about 4 MPa or less). A pressure-sensitive adhesive sheet with a lower stress of 300% A ₃₀₀ can be significantly stretched and deformed with a lower stress to reduce the bonding area. Therefore, it is suitable for reducing the tensile peeling stress B. The lower limit of A ₃₀₀ is not particularly limited, but from the viewpoint of sticking workability of the adhesive sheet, it is usually appropriate to set it to about 0.5 MPa or more (for example, about 1.0 MPa or more), and about 1.5 MPa or more. (For example, about 2.0 MPa or more) may be used.

The 300% tensile stress A ₃₀₀ of the pressure-sensitive adhesive sheet is measured by using the pressure-sensitive adhesive sheet as a test piece in accordance with the method for measuring "tensile stress" described in JIS K 7311: 1995. More specifically, in a tensile test in which a No. 3 dumbbell-shaped test piece (width 5 mm, marked line spacing 20 mm) is pulled under a tensile speed of 300 mm / min, when the marked line spacing is extended by 300%. The stress [MPa] (that is, the stress when a 300% elongation is applied. Here, the stress when the marked line spacing is extended to 80 mm) is defined as a 300% elongation stress A ₃₀₀ . As the tensile tester, the product name "Autograph AG-10G type tensile tester" manufactured by Shimadzu Corporation can be used. A similar method can be adopted for the examples described later. The 300% tensile stress A ₃₀₀ can be adjusted by, for example, selection of a constituent material of the pressure-sensitive adhesive sheet (for example, selection of a base material type, base material composition, etc.), a molding method, or the like.

The 100% elongation stress A ₁₀₀ of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, but is usually preferably less than about 7 MPa (for example, about 5 MPa or less), and preferably about 4 MPa or less (for example, about 3. 5 MPa or less). Such an adhesive sheet exhibiting 100% tensile stress A ₁₀₀ is suitable for reducing tensile peeling stress B. The lower limit of A ₁₀₀ is not particularly limited, but from the viewpoint of sticking workability and the like, it is usually appropriate to set it to about 0.5 MPa or more (for example, about 1.0 MPa or more). The 100% elongation stress A ₁₀₀ of the adhesive sheet is measured in the same manner as the 300% elongation stress A _{300 of} the adhesive sheet described above, but as the stress [MPa] when the marked line spacing is extended by 100%. The 100% tensile stress A ₁₀₀ can be adjusted by, for example, selection of a constituent material of the pressure-sensitive adhesive sheet (for example, selection of a base material type, base material composition, etc.), a molding method, or the like.

In the pressure-sensitive adhesive sheet according to a preferred embodiment, the 300% elongation stress A ₃₀₀ of the pressure-sensitive adhesive sheet is approximately 1.5 times or less the 100% elongation stress A ₁₀₀ . That is, A ₃₀₀ / A ₁₀₀ is about 1.5 or less. Such an adhesive sheet can be significantly stretched and deformed to reduce the adhesive area while suppressing an increase in stretch stress due to an increase in the degree of stretch. Therefore, it is suitable for reducing the tensile peeling stress B. In a more preferred embodiment, A ₃₀₀ / A ₁₀₀ can be approximately 1.3 or less (and even approximately 1.2 or less). A ₃₀₀ / A ₁₀₀ may be approximately 1.1 or less. The lower limit of A ₃₀₀ / A ₁₀₀ is not particularly limited, but is usually about 0.5 or more, and typically about 0.8 or more (for example, about 0.9 or more). The A ₃₀₀ / A ₁₀₀ can be adjusted by appropriately adjusting one or both of the A ₁₀₀ and the A ₃₀₀ .

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the 25% elongation stress A ₂₅ of the pressure-sensitive adhesive sheet can be less than about 7 MPa (more preferably about 5 MPa or less, for example about 3 MPa or less). According to the adhesive sheet having a lower tensile stress A ₂₅ of 25%, when the adhesive sheet is removed from the adherend by pulling and stretching and deforming, the resistance at the start of pulling becomes smaller and the tensile removability tends to be improved. There is. Further, from the viewpoint of sticking workability of the pressure-sensitive adhesive sheet, the 25% elongation stress A ₂₅ of the pressure-sensitive adhesive sheet is usually preferably about 0.5 MPa or more (for example, about 1.0 MPa or more). The pressure-sensitive adhesive sheet disclosed herein can be preferably carried out in an embodiment in which the 25% elongation stress A ₂₅ is about 1.5 MPa or more (for example, about 1.8 MPa or more). As described above, the fact that the 25% elongation stress A ₂₅ is not too low can be advantageous in terms of workability and shape stability. The 25% elongation stress A ₂₅ of the adhesive sheet is measured in the same manner as the 300% elongation stress A _{300 of} the adhesive sheet described above, but as the stress [MPa] when the marked line spacing is extended by 25%. The 25% tensile stress A ₂₅ can be adjusted by, for example, selection of a constituent material of the pressure-sensitive adhesive sheet (for example, selection of a base material type, base material composition, etc.), a molding method, or the like.

In the pressure-sensitive adhesive sheet according to a preferred embodiment, the 100% elongation stress A ₁₀₀ may be approximately 2.5 times or less the 25% elongation stress A ₂₅ . That is, A ₁₀₀ / A ₂₅ can be approximately 2.5 or less. Such an adhesive sheet can be significantly stretched and deformed while suppressing an increase in stretch stress due to an increase in the degree of stretch. Therefore, it is suitable for reducing the tensile peeling stress B. In a more preferred embodiment, A ₁₀₀ / A ₂₅ can be approximately 2.2 or less (and even approximately 2.0 or less, such as approximately 1.7 or less). A ₁₀₀ / A ₂₅ may be approximately 1.5 or less. The lower limit of A ₁₀₀ / A ₂₅ is not particularly limited, but is usually about 0.5 or more, and about 0.8 or more (for example, about 0.9 or more) is appropriate. A ₁₀₀ / A ₂₅ can be adjusted by appropriately adjusting one or both of A ₂₅ and A ₁₀₀ .

The tensile recovery rate of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited. It may be advantageous for the pressure-sensitive adhesive sheet to exhibit a tensile recovery rate of a predetermined value or higher in terms of preventing tearing of the pressure-sensitive adhesive sheet and improving workability. From this point of view, the tensile recovery rate of the pressure-sensitive adhesive sheet is usually preferably about 10% or more (for example, about 25% or more), and preferably more than 50%. The tensile recovery rate may be substantially 100%, may be about 95% or less, and may be about 90% or less (for example, about 85% or less). In a preferred embodiment, the tensile recovery rate of the pressure-sensitive adhesive sheet can be approximately 80% or less (eg, approximately 70% or less). The adhesive sheet, which is peeled off from the adherend by tensile peeling and released from tensile stress, contracts due to elastic repulsion, and may hit an operator's hand or the like to give an unpleasant impact. The tensile recovery rate of the pressure-sensitive adhesive sheet is not too high, which may be advantageous from the viewpoint of preventing such an unpleasant event or reducing the unpleasantness.

The tensile recovery rate is measured by the following method.
[Measurement of tensile recovery rate]
For the adhesive sheet, a tensile test is performed in which the specific section distance L ₀ of the adhesive sheet is stretched by 200%. When the length of the specific section is L ₁ after 5 minutes have passed since the adhesive sheet was stretched by 200% and released, the formula: tensile recovery rate (%) = (1- (L _{1 −} L _0). ) / (L _2- L ₀ )) × 100; The tensile recovery rate is obtained. Here, L ₂ is the length of the specific section when the extension of 200% is added to the specific section distance L ₀ .
More specifically, in accordance with JIS K 7311: 1995, a No. 3 dumbbell-shaped test piece (width 5 mm, marked line spacing 20 mm) is used to stretch 200% at a tensile speed of 300 mm / min. In other words, the test piece is pulled until the marked line spacing extends to 60 mm. Then, the length L ₁ (mm) between the marked lines after 5 minutes from the tension was measured, and the formula: tensile recovery rate (%) = (1- (L _{1 −} L ₀ ) / (L ₂ ). -L ₀ )) × 100; The tensile recovery rate is obtained. In this method, L ₀ is the initial marked line spacing of 20 mm, and L ₂ is the length between the marked lines when stretched 200%. The tensile tester and others are basically the same as in the case of elongation at break described above. The tensile direction in the above test is not particularly limited, but it is preferable to match the tensile direction with the longitudinal direction of the pressure-sensitive adhesive sheet or its long portion. The tensile recovery rate can be adjusted, for example, by selecting the base material type.

The pressure-sensitive adhesive sheet disclosed herein preferably exhibits a shear adhesive force of approximately 0.10 MPa or more. As a result, the adhesive sheet adheres well to the adherend. Since the adhesive sheet exhibiting the adhesive force exhibits a strong stress against a force (that is, a shearing force) that tries to shift the adhesive interface, it can be a highly reliable adhesive means in a usage mode exposed to the shearing force. .. The shear adhesive force is more preferably about 0.15 MPa or more (more preferably about 0.20 MPa or more, for example, about 0.25 MPa or more). The upper limit of the shear adhesive force is not particularly limited. If the shear adhesive force is too high, the tensile removability and the adhesive residue prevention property tend to decrease. Therefore, it is usually appropriate to set the shear adhesive force to about 3 MPa or less (for example, about 2 MPa or less). In a preferred embodiment, the shear adhesive force may be about 1.0 MPa or less (further, about 0.7 MPa or less, for example, about 0.5 MPa or less).

The shear adhesive force can be measured by the method described below. An adhesive sheet (typically a double-sided adhesive sheet) is cut into a size of 20 mm × 20 mm to prepare a measurement sample. In an environment of 23 ° C. and 50% RH, each adhesive surface of the measurement sample is superposed on the surfaces of two stainless steel plates, and a 2 kg roller is reciprocated once for crimping. After leaving this in the same environment for 30 minutes, the shear adhesive force [MPa] is measured using a tensile tester under the conditions of a tensile speed of 300 mm / min and a peeling angle of 0 degrees. Specifically, as shown in FIG. 3, one adhesive surface 800A of the measurement sample 800 is attached to the stainless steel plate 801 and the other adhesive surface 800B of the measurement sample 800 is attached to the stainless steel plate 802 and crimped. This is pulled in the direction of the arrow in FIG. 3 (that is, the shearing direction) at the above speed, and the peel strength per 20 mm × 20 mm is measured. The shear adhesive force [MPa] is obtained from the obtained value. In the case of a single-sided adhesive sheet (single-sided adhesive sheet), the non-adhesive surface of the sheet may be fixed to a stainless steel plate with an adhesive or the like, and the other may be measured in the same manner as described above. As the tensile tester, a universal tensile compression tester (product name "TG-1kN", manufactured by Minebea) can be used. The same method is adopted for the examples described later.

<Adhesive layer>
(Base polymer)
The pressure-sensitive adhesive layer disclosed herein (in the case of a double-sided pressure-sensitive adhesive sheet with a base material, includes a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer; the same applies hereinafter) is an acrylic polymer known in the field of pressure-sensitive adhesives. , Rubber-based polymer, polyester-based polymer, urethane-based polymer, polyether-based polymer, silicone-based polymer, polyamide-based polymer, fluorine-based polymer, and other various rubber-like polymers are included as a base polymer. obtain. As will be described in detail later, the pressure-sensitive adhesive layer disclosed herein is preferably an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer, a rubber-based pressure-sensitive adhesive layer containing a rubber-based polymer as a base polymer, and a urethane-based polymer. Is a urethane-based pressure-sensitive adhesive layer containing the above as a base polymer. Alternatively, the pressure-sensitive adhesive layer may be a combination of an acrylic polymer and a rubber-based polymer as the base polymer.

(Acrylic polymer)
In a preferred embodiment, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer from the viewpoints of adhesive properties (typically, adhesive strength), molecular design, stability over time, and the like. In addition, in this specification, a "base polymer" of a pressure-sensitive adhesive means a main component (typically, a component contained in excess of 50% by weight) of a polymer component contained in the pressure-sensitive adhesive.

As the acrylic polymer, for example, a polymer of a monomer raw material containing an alkyl (meth) acrylate as a main monomer and further containing a submonomer having copolymerizability with the main monomer is preferable. Here, the main monomer means a component that accounts for more than 50% by weight of all the monomer components in the monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be preferably used.
CH ₂ = C (R ¹ ) COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. Further, R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of carbon atoms may be referred to as “C _1-20 ”). From the viewpoint of the storage elastic modulus of the pressure-sensitive adhesive, alkyl (meth) acrylate in which R ² is a chain alkyl group of C _1-14 (for example, C _2-10 , typically C _4-8 ) is preferable, and R Alkyl acrylates in which ¹ is a hydrogen atom and R ² is a chain alkyl group of C _4-8 are more preferable.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 chain alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meta) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , Octyl (meth) acrylate, Isooctyl (meth) acrylate, Nonyl (meth) acrylate, Isononyl (meth) acrylate, Decyl (meth) acrylate, Isodecyl (meth) acrylate, Undecyl (meth) acrylate, Lauryl (meth) acrylate, Tridecyl Examples thereof include (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecil (meth) acrylate, and ecocil (meth) acrylate. .. These alkyl (meth) acrylates can be used alone or in combination of two or more. Preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). BA is more preferable from the viewpoint of adhesive properties and prevention of adhesive residue.

The blending ratio of the main monomer in all the monomer components is preferably about 70% by weight or more (for example, about 85% by weight or more, typically about 90% by weight or more). The upper limit of the blending ratio of the main monomer is not particularly limited, but it is usually preferably about 99.5% by weight or less (for example, about 99% by weight or less). When C _4-8 alkyl acrylate is used as the monomer component, the proportion of C _4-8 alkyl acrylate in the alkyl (meth) acrylate contained in the monomer component is preferably about 70% by weight or more. It is more preferably about 90% by weight or more, and further preferably about 95% by weight or more (typically about 99% by weight or more and about 100% by weight or less). The technique disclosed herein can be preferably carried out in an embodiment in which approximately 50% by weight or more (for example, approximately 60% by weight or more) of all monomer components is BA. In a preferred embodiment, the total monomer component may further contain 2EHA in a smaller proportion than BA.

A sub-monomer having copolymerizability with the main monomer, alkyl (meth) acrylate, can be useful for introducing cross-linking points into the acrylic polymer and enhancing the cohesive force of the acrylic polymer. Examples of the sub-monomer include a carboxy group-containing monomer, a hydroxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, a keto group-containing monomer, a monomer having a nitrogen atom-containing ring, and an alkoxysilyl group-containing monomer. One or more functional group-containing monomers such as an imide group-containing monomer and an epoxy group-containing monomer can be used. For example, from the viewpoint of improving the cohesive force, an acrylic polymer in which a carboxy group-containing monomer and / or a hydroxyl group-containing monomer is copolymerized as the submonomer is preferable. Preferable examples of the carboxy group-containing monomer include acrylic acid (AA) and methacrylic acid (MAA). Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth). Examples thereof include hydroxyalkyl (meth) acrylates such as acrylates and unsaturated alcohols. Of these, hydroxyalkyl (meth) acrylate is preferable, and 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA) are more preferable.

The amount of the submonomer may be appropriately selected so as to achieve a desired cohesive force, and is not particularly limited. Usually, from the viewpoint of achieving both adhesive strength and cohesive strength in a well-balanced manner, it is appropriate that the amount of submonomers is about 0.5% by weight or more in the total monomer components of the acrylic polymer, and preferably about. 1% by weight or more. The amount of the submonomer is appropriately about 30% by weight or less, preferably about 10% by weight or less (for example, about 5% by weight or less) in the total monomer components. When the carboxy group-containing monomer is copolymerized with the acrylic polymer, the content of the carboxy group-containing monomer is determined from the viewpoint of achieving both adhesive strength and cohesive strength in all the monomer components used for the synthesis of the acrylic polymer. It is preferably about 0.1% by weight or more (for example, about 0.2% by weight or more, typically about 0.5% by weight or more), and about 10% by weight or less (for example, about 8% by weight or less, Typically, it is preferably about 5% by weight or less). When the hydroxyl group-containing monomer is copolymerized with the acrylic polymer, the content of the hydroxyl group-containing monomer is approximately 0 in all the monomer components used for the synthesis of the acrylic polymer from the viewpoint of achieving both adhesive strength and cohesive force. It is preferably .001% by weight or more (for example, about 0.01% by weight or more, typically about 0.02% by weight or more), and about 10% by weight or less (for example, about 2% by weight or less). Is preferable.

The acrylic polymer disclosed herein may be copolymerized with a monomer (other monomer) other than the above as long as the effect of the present invention is not significantly impaired. The other monomers can be used, for example, for the purpose of adjusting the glass transition temperature of the acrylic polymer, adjusting the adhesive performance (for example, peelability), and the like. For example, examples of the monomer capable of improving the cohesive force of the pressure-sensitive adhesive include a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, vinyl esters, and an aromatic vinyl compound. As the above-mentioned other monomers, one kind may be used alone, or two or more kinds may be used in combination. Among them, vinyl esters are mentioned as a preferable example. Specific examples of vinyl esters include vinyl acetate (VAc), vinyl propionate, vinyl laurate, and the like. Of these, VAc is preferable. The content of the other monomers is preferably about 30% by weight or less (for example, about 10% by weight or less), and for example, about 0.01% by weight or more, based on all the monomer components used for the synthesis of the acrylic polymer. (Typically, it can be about 0.1% by weight or more).

From the viewpoint of impact resistance and the like, the copolymer composition of the acrylic polymer has a glass transition temperature (Tg) of the polymer of about -15 ° C or lower (typically -25 ° C or lower, for example, -40 ° C or lower). It is appropriate that it is designed to be. The Tg of the acrylic polymer is usually about −70 ° C. or higher, for example, about −60 ° C. or higher. The Tg of the acrylic polymer is typically about −70 ° C. or higher and about −15 ° C. or lower, preferably about −60 ° C. or higher and about −25 ° C. or lower, for example, about −60 ° C. or higher and about −40 ° C. It is as follows.

The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of the monomers used in the synthesis of the polymer). Here, the Tg of the acrylic polymer is Fox based on the Tg of the homopolymer of each monomer constituting the polymer and the weight fraction (copolymerization ratio based on the weight) of the monomer. The value obtained from the formula of. As shown below, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1 / Tg = Σ (Wi / Tgi)
In the Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer. As the Tg of the homopolymer, the value described in the publicly known material shall be adopted.

In the technique disclosed herein, the following values are specifically used as the Tg of the homopolymer.
2-Ethylhexyl acrylate-70 ° C
Butyl acrylate -55 ° C
Vinyl acetate 32 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° C
2-Hydroxyethyl acrylate -15 ° C
4-Hydroxybutyl acrylate-40 ° C
For Tg of homopolymers other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. The highest value is adopted for the monomers for which multiple types of values are described in this document. If it is not described in the Polymer Handbook, the value obtained by the measurement method described in JP-A-2007-51271 shall be used.

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for the acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a massive polymerization method, and a suspension polymerization method, are appropriately adopted. be able to. For example, a solution polymerization method can be preferably used. As a monomer supply method for solution polymerization, a batch charging method, a continuous supply (dropping) method, a split feeding (dropping) method, or the like in which all the monomer raw materials are supplied at once can be appropriately adopted. The polymerization temperature can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, and the like, and can be, for example, about 20 ° C. or higher (typically 40 ° C. or higher). The temperature can be about 170 ° C. or lower (typically 140 ° C. or lower). Alternatively, photopolymerization performed by irradiating light such as UV (typically performed in the presence of a photopolymerization initiator), radiation polymerization performed by irradiating radiation such as β-rays and γ-rays, etc. Active energy ray irradiation polymerization may be adopted.

The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons), acetate esters such as ethyl acetate, aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane are preferably used.

The initiator used for the polymerization can be appropriately selected from conventionally known polymerization initiators according to the type of polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) may be preferably used. Other examples of polymerization initiators include persulfates such as potassium persulfate; peroxide-based initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; aromatic carbonyl compounds. ; Etc. can be mentioned. Yet another example of the polymerization initiator is a redox-based initiator in which a peroxide and a reducing agent are combined. Such a polymerization initiator can be used alone or in combination of two or more. The amount of the polymerization initiator used may be a normal amount, for example, about 0.005 parts by weight or more and about 1 part by weight or less (typically about 0.01 parts by weight) with respect to 100 parts by weight of all the monomer components. It can be selected from a range of about 1 part or more and about 1 part by weight or less).

The weight average molecular weight of the base polymer (preferably an acrylic polymer) disclosed herein (Mw) of, is not, it may be in the range, for example 10 × 10 ⁴ or more 500 × 10 ⁴ or less particularly limited. From the viewpoint of balancing the cohesive force and the adhesive force at a high level, the Mw of the base polymer (preferably an acrylic polymer) is preferably 10 × 10 ⁴ or more, more preferably 20 × 10 ⁴ or more, and further preferably 35. × 10 ⁴ or more, preferably 150 × 10 ⁴ or less, more preferably 110 × 10 ⁴ or less, still more preferably 90 × 10 ⁴ or less (typically 75 × 10 ⁴ or less, for example 65 × 10 ^4). Below). In one embodiment, the Mw of the base polymer is preferably 10 × 10 ⁴ or more and 150 × 10 ⁴ or less, more preferably 20 × 10 ⁴ or more and 110 × 10 ⁴ or less (for example, 20 × 10 ⁴ or more and 75 × 10 ⁴ or less). More preferably, it can be 35 × 10 ⁴ or more and 90 × 10 ⁴ or less (for example, 35 × 10 ⁴ or more and 65 × 10 ⁴ or less). Here, Mw refers to a standard polystyrene-equivalent value obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, the model name "HLC-8320GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) may be used. The same applies to the examples described later.

(Rubber polymer)
In another preferred embodiment, the pressure-sensitive adhesive layer is made of a rubber-based pressure-sensitive adhesive. The rubber-based pressure-sensitive adhesive according to a more preferred embodiment contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound as a base polymer. The monovinyl-substituted aromatic compound refers to a compound in which one functional group having a vinyl group is bonded to an aromatic ring. A typical example of the aromatic ring is a benzene ring (which may be a benzene ring substituted with a functional group having no vinyl group (for example, an alkyl group)). Specific examples of the monovinyl-substituted aromatic compound include styrene, α-methylstyrene, vinyltoluene, vinylxylene and the like. Specific examples of the conjugated diene compound include 1,3-butadiene, isoprene and the like. Such block copolymers can be used alone or in combination of two or more as a base polymer.

In the A segment (hard segment) of the block copolymer, the copolymerization ratio of the monovinyl-substituted aromatic compound (two or more thereof can be used in combination) is 70% by weight or more (more preferably 90% by weight or more). It may be substantially 100% by weight.). In the B segment (soft segment) of the block copolymer, the copolymerization ratio of the conjugated diene compound (two or more thereof can be used in combination) is 70% by weight or more (more preferably 90% by weight or more), which is substantially the same. It may be 100% by weight.). According to such a block copolymer, a higher performance pressure-sensitive adhesive sheet can be realized.

The block copolymer may be in the form of a diblock body, a triblock body, a radial body, a mixture thereof, or the like. In the triblock body and the radial body, it is preferable that the A segment (for example, styrene block) is arranged at the end of the polymer chain. This is because the A segments arranged at the ends of the polymer chains are likely to gather to form a domain, thereby forming a pseudo crosslinked structure and improving the cohesiveness of the pressure-sensitive adhesive. The block copolymer in the technique disclosed herein has, for example, a diblock body ratio of 30% by weight or more (more preferably 40% by weight) from the viewpoint of adhesive strength (peeling strength) and repulsion resistance to the adherend. As described above, more preferably 50% by weight or more, particularly preferably 60% by weight or more, typically 65% by weight or more, for example 70% by weight or more) can be preferably used. Further, from the viewpoint of resistance to continuously applied stress, those having a diblock body ratio of 90% by weight or less (more preferably 85% by weight or less, for example 80% by weight or less) can be preferably used. For example, it is preferable to use a block copolymer having a diblock ratio of 60% by weight or more and 85% by weight or less.

(Styrene block copolymer)
In a preferred embodiment of the technique disclosed herein, the base polymer is a styrene-based block copolymer. For example, it can be preferably carried out in an embodiment in which the base polymer contains at least one of a styrene isoprene block copolymer and a styrene butadiene block copolymer. Of the styrene-based block copolymers contained in the pressure-sensitive adhesive, the proportion of styrene-isoprene block copolymer is 70% by weight or more, the proportion of styrene-butadiene block copolymer is 70% by weight or more, or styrene. The total ratio of the isoprene block copolymer and the styrene-butadiene block copolymer is preferably 70% by weight or more. In a preferred embodiment, substantially all of the styrene-based block copolymers (for example, 95% by weight or more and 100% by weight or less) are styrene isoprene block copolymers. In another preferred embodiment, substantially all of the styrene-based block copolymers (eg, 95% by weight or more and 100% by weight or less) are styrene-butadiene block copolymers. According to such a composition, an adhesive sheet having excellent repulsion resistance and a good balance with other adhesive properties can be preferably realized.

The styrene-based block copolymer may be in the form of a diblock body, a triblock body, a radial body, a mixture thereof, or the like. In the triblock body and the radial body, it is preferable that the styrene block is arranged at the end of the polymer chain. This is because the styrene blocks arranged at the ends of the polymer chains are likely to gather to form a styrene domain, thereby forming a pseudo-crosslinked structure and improving the cohesiveness of the pressure-sensitive adhesive. As the styrene-based block copolymer used in the technique disclosed herein, for example, the diblock ratio is 30% by weight or more (more preferably) from the viewpoint of adhesive strength (peeling strength) to the adherend and repulsion resistance. 40% by weight or more, more preferably 50% by weight or more, particularly preferably 60% by weight or more, typically 65% by weight or more) can be preferably used. A styrene-based block copolymer having a diblock ratio of 70% by weight or more (for example, 75% by weight or more) may be used. Further, from the viewpoint of holding power and the like, a styrene-based block copolymer having a diblock compound ratio of 90% by weight or less (more preferably 85% by weight or less, for example, 80% by weight or less) can be preferably used. For example, a styrene-based block copolymer having a diblock ratio of 60% by weight or more and 85% by weight or less can be preferably adopted.

The styrene content of the styrene-based block copolymer can be, for example, 5% by weight or more and 40% by weight or less. From the viewpoint of repulsion resistance and holding power, a styrene-based block copolymer having a styrene content of 10% by weight or more (more preferably larger than 10% by weight, for example, 12% by weight or more) is usually preferable. Further, from the viewpoint of adhesive strength to the adherend, the copolymer weight of the styrene-based block having a styrene content of 35% by weight or less (typically 30% by weight or less, more preferably 25% by weight or less, for example, less than 20% by weight). Coalescence is preferred. For example, a styrene-based block copolymer having a styrene content of 12% by weight or more and less than 20% by weight can be preferably adopted.

(Urethane polymer)
In still another preferred embodiment, the pressure-sensitive adhesive layer is made of a urethane-based pressure-sensitive adhesive. Here, the urethane-based pressure-sensitive adhesive (layer) refers to a pressure-sensitive adhesive (layer) containing a urethane-based polymer as a base polymer. The urethane-based pressure-sensitive adhesive is typically made of a urethane-based resin containing a urethane-based polymer obtained by reacting a polyol with a polyisocyanate compound as a base polymer. The urethane-based polymer is not particularly limited, and an appropriate urethane-based polymer (ether-based polyurethane, ester-based polyurethane, carbonate-based polyurethane, etc.) that can function as an adhesive can be adopted. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol and the like. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate and the like.

(Filler particles)
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein may contain filler particles. By including the filler particles in the pressure-sensitive adhesive layer, the filler particles can contribute to the reduction of the tensile stress B when the pressure-sensitive adhesive sheet is stretched and deformed. As a result, both the maintenance of the initial adhesive force A and the reduction of the tensile peeling stress B are realized. This point will be described. The filler particles contained in the pressure-sensitive adhesive layer may exist in a state of being exposed on the pressure-sensitive adhesive surface or in a state of being encapsulated in the pressure-sensitive adhesive layer. The filler particles exposed on the adhesive surface reduce the area of the adhesive on the adhesive surface and improve the slipperiness of the adhesive interface in the shear direction. As a result, the tensile peeling stress B is reduced, but the decrease in the pressure-sensitive adhesive area on the adhesive surface also brings about a decrease in the initial adhesive force A. On the other hand, the filler particles existing inside the pressure-sensitive adhesive layer are considered to greatly contribute to the reduction of the tensile peeling stress B without lowering the initial pressure-sensitive adhesive force A. The main reason for this is not particularly limited, but a change in the state of the pressure-sensitive adhesive layer due to deformation of the pressure-sensitive adhesive sheet can be considered. Specifically, since the tensile peeling is a mode in which the adhesive is peeled off in a direction parallel to the adhesive surface (tension peeling direction, also referred to as a shearing direction), the adhesive sheet is deformed in that direction during the tensile peeling. .. The extensible pressure-sensitive adhesive sheet stretches with respect to the above tension, and the pressure-sensitive adhesive layer is deformed accordingly. For example, when the film-like base material that supports the pressure-sensitive adhesive layer has stretchability with respect to tension, the pressure-sensitive adhesive layer is also significantly deformed as the base material is stretched. It is considered that the deformation of the pressure-sensitive adhesive layer increases the amount of the filler particles contained in the pressure-sensitive adhesive layer exposed to the pressure-sensitive adhesive surface and improves the slipperiness in the shearing direction at the bonding interface. It is also considered that the pressure-sensitive adhesive (tacky component) is deformed by tensile peeling in the pressure-sensitive adhesive layer, whereas the filler particles behave differently from the pressure-sensitive adhesive in the pressure-sensitive adhesive layer. It is also considered that the difference in the behavior of the pressure-sensitive adhesive and the filler particles with respect to this tensile peeling contributes to the reduction of the tensile peeling stress. It is considered that the above-mentioned changes in the surface state of the pressure-sensitive adhesive layer and the behavior of the components of the pressure-sensitive adhesive layer do not become apparent or can be ignored by, for example, 90-degree peeling or 180-degree peeling due to the difference in the peeling mode. Be done. However, it is typically considered that the stress change is greatly affected during tensile peeling. As a result, it is considered that the filler particles contained in the pressure-sensitive adhesive layer greatly contribute to both the maintenance of the initial pressure-sensitive adhesive force A and the reduction of the tensile peeling stress B. The effect of containing the filler particles is particularly remarkable in the adhesive sheet having extensibility. Further, in an stretchable pressure-sensitive adhesive sheet having a base material, the mechanical properties of the base material can typically contribute significantly to the adhesive strength (typically 180 degree peel strength), so that the pressure-sensitive adhesive composition (for example, pressure-imparting) is applied. It is considered that the contribution of the agent, the additive component such as the cross-linking agent, etc.) to the adhesive strength is relatively small. In such a pressure-sensitive adhesive sheet, by incorporating filler particles in the pressure-sensitive adhesive layer, an action of selectively reducing only the tensile peeling stress B while maintaining the initial pressure-sensitive adhesive force A is preferably realized.

The type of filler particles used is not particularly limited. For example, particulate or fibrous fillers can be used. The constituent materials of the filler particles (typically particulate fillers) are metals such as copper, silver, gold, platinum, nickel, aluminum, chromium, iron, stainless steel; aluminum oxide, silicon oxide (silicon dioxide), oxidation. Metal oxides such as titanium, zirconium oxide, zinc oxide, tin oxide, copper oxide, nickel oxide; aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, Metal hydroxides and hydrated metal compounds such as barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, hydrotalcite, dousonite, borosand, zinc borate; silicon carbide, boron carbide, Carbide such as nitrogen hydroxide and calcium hydroxide; Nitride such as aluminum hydroxide, silicon nitride, boron nitride and gallium nitride; Carbonate such as calcium carbonate; Titanate such as barium titanate and potassium titanate; Carbon black, carbon tube (Carbon nanotubes), carbon fibers, carbon-based substances such as diamond; glass; inorganic materials such as; polystyrene, acrylic resin (for example, polymethylmethacrylate), phenol resin, benzoguanamine resin, urea resin, silicone resin, polyester, polyurethane, polyethylene , Polypropylene, polyamide (eg nylon, etc.), polyimide, polymers such as polyvinylidene chloride; etc. Alternatively, natural raw material particles such as volcanic shirasu, clay, and sand may be used. As the fibrous filler, various synthetic fiber materials and natural fiber materials can be used. These can be used alone or in combination of two or more. Among them, a particulate filler is preferable from the viewpoint of reducing tensile peeling stress, and among them, a particulate filler composed of an inorganic material (for example, aluminum hydroxide) is preferably used.

The average particle size of the filler particles is preferably less than 50% of the thickness of the pressure-sensitive adhesive layer. Here, the average particle size of the filler particles in the present specification means a particle size (50% median diameter) at which the cumulative particle size based on the weight is 50% in the particle size distribution obtained by the measurement based on the sieving method. Say. If the average particle size of the filler particles is less than 50% of the thickness of the pressure-sensitive adhesive layer, it can be said that 50% by weight or more of the filler particles contained in the pressure-sensitive adhesive layer has a particle size smaller than the thickness of the pressure-sensitive adhesive layer. .. Since 50% by weight or more of the filler particles contained in the pressure-sensitive adhesive layer has a particle size smaller than the thickness of the pressure-sensitive adhesive layer, a good surface condition (for example, smoothness) is maintained on the surface (adhesive surface) of the pressure-sensitive adhesive layer. Greater tendency to be maintained. This is preferable from the viewpoint of improving the adhesiveness (for example, initial adhesive force A) by improving the adhesiveness with the adherend. In a preferred embodiment, the average particle size of the filler particles can be 45% or less (eg 40% or less) of the thickness of the pressure-sensitive adhesive layer.

The average particle size of the filler particles is preferably larger than 3% of the thickness of the pressure-sensitive adhesive layer. According to the filler particles having the above average particle size in relation to the thickness of the pressure-sensitive adhesive layer, the tensile peeling stress B of the pressure-sensitive adhesive sheet tends to be effectively reduced. From the viewpoint of obtaining a higher effect, the average particle size of the filler can be 4% or more of the thickness of the pressure-sensitive adhesive layer, may be 10% or more, and may be 15% or more. .. In a preferred embodiment, the average particle size of the filler particles contained in the pressure-sensitive adhesive layer can be 20% or more (more preferably 25% or more, for example 30% or more) of the thickness of the pressure-sensitive adhesive layer.

In a preferred embodiment, 60% by weight or more (for example, 70% by weight or more, typically 80% by weight or more) of the filler particles contained in the pressure-sensitive adhesive layer has a particle size smaller than the thickness of the pressure-sensitive adhesive layer. It is more preferable that substantially the entire amount (typically 99% by weight or more and 100% by weight or less) of the filler particles contained in the pressure-sensitive adhesive layer has a particle size smaller than the thickness of the pressure-sensitive adhesive layer. In another preferred embodiment, from the viewpoint of improving the surface condition of the adhesive surface, 40% by weight or more (for example, 50% by weight or more, typically 55% by weight or more) of the filler particles contained in the pressure-sensitive adhesive layer is used. It has a particle size smaller than 2/3 (ie, 2/3 T, more preferably 1/2, or 1 / 2T) of the thickness T of the pressure-sensitive adhesive layer. In addition, the fact that X% by weight or more of the filler particles has a particle size smaller than Y means that the cumulative particle size (weight standard) up to the particle size Y (μm) is X in the particle size distribution obtained by the measurement based on the sieving method. It means that it is less than (% by weight). The proportion (% by weight) of the filler particles having a predetermined particle size can be determined based on the particle size distribution.

In a preferred embodiment, the filler particles contained in the pressure-sensitive adhesive layer are 50% by weight or more (for example, 70% by weight or more, typically 90% by weight or more) of particles having a particle size of less than 30 μm. In the pressure-sensitive adhesive layer containing such filler particles, the smoothness of the pressure-sensitive adhesive surface is not easily impaired even if the thickness of the pressure-sensitive adhesive layer is relatively small. Therefore, even with a thinner pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet that preferably has both a sufficient adhesive function at the time of use and excellent tensile removal property at the time of removal can be preferably realized. This is advantageous from the viewpoint of reducing the total thickness of the adhesive sheet. In one embodiment, the filler particles contained in the pressure-sensitive adhesive layer are 50% by weight or more (more preferably 70% by weight or more, further 80% by weight) particles having a particle size of less than 20 μm (more preferably less than 15 μm, for example, less than 10 μm). % Or more) is more preferable.

In a preferred embodiment, the proportion of the filler particles contained in the pressure-sensitive adhesive layer having a particle size of less than 1 μm is 50% by weight or less. From the viewpoint of reducing tensile peel stress, it is desirable that the particle size of the filler particles has a certain size. Further, it is preferable that the amount of fine particles is limited in terms of productivity, for example, in the preparation of the pressure-sensitive adhesive composition, an excessive increase in viscosity does not occur. Of the filler particles contained in the pressure-sensitive adhesive layer, the proportion of particles having a particle size of less than 1 μm (for example, less than 2 μm, typically less than 5 μm) is 30% by weight or less (for example, 10% by weight or less, typically less than 5 μm). 5% by weight or less) is more preferable.

The average particle size of the entire filler particles contained in the pressure-sensitive adhesive layer is usually preferably 0.5 μm or more, and preferably 0.8 μm or more. As the average particle size increases, the effect of reducing tensile peel stress tends to improve. In one aspect, the average particle size may be 1 μm or more (typically more than 1 μm, for example 2 μm or more), 3 μm or more, or 5 μm or more. The upper limit of the average particle size may be, for example, 50 μm or less. From the viewpoint of reducing the total thickness of the pressure-sensitive adhesive sheet, the average particle size of the filler particles is usually 30 μm or less, and preferably 20 μm or less (for example, 18 μm or less). The pressure-sensitive adhesive sheet disclosed herein can be preferably carried out in an embodiment having a pressure-sensitive adhesive layer containing filler particles having an average particle size of 15 μm or less (more preferably 12 μm or less, for example, 10 μm or less).

The shape of the filler particles is not particularly limited, and may be, for example, a bulk shape, a needle shape, a plate shape (for example, a hexagonal plate shape), a layered shape, or the like. The concept of bulk shape includes, for example, spherical shape, rectangular parallelepiped shape, crushed shape or a variant shape thereof. The shape of the filler particles is preferably a bulk shape, and more preferably a spherical shape.

The average aspect ratio of the filler particles is not particularly limited, and from the viewpoint of reducing tensile peel stress, less than about 100 is suitable, preferably less than 50, more preferably less than 10 (for example, less than 5, typically less than 2). Can be. Here, the average aspect ratio of the filler particles is obtained as the average value of the aspect ratios of the particles represented by the major axis / minor axis of the filler particles. The major axis typically refers to the maximum transfer length of the particles to be measured, and the minor axis typically refers to the minimum transfer length of the particles to be measured. The average aspect ratio can be grasped through transmission electron microscope observation.

In the pressure-sensitive adhesive layer containing the filler particles, the content of the filler particles can be set so as to obtain a desired effect, and is not particularly limited. The content of the filler particles in the pressure-sensitive adhesive layer is, for example, about 0.5 parts by weight or more (typically about 1 part by weight or more, for example, about 3 parts by weight) with respect to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive layer. It can be about 100 parts by weight or less (typically less than about 100 parts by weight). The content of the filler particles with respect to 100 parts by weight of the base polymer may be more than 5 parts by weight or more than 10 parts by weight. The pressure-sensitive adhesive sheet disclosed herein is preferably carried out in an embodiment in which the content of the filler particles with respect to 100 parts by weight of the base polymer is about 12 parts by weight or more (for example, about 15 parts by weight or more, further about 20 parts by weight or more). Can be done. In a preferred embodiment, the content of the filler particles per 100 parts by weight of the base polymer may be about 25 parts by weight or more (typically more than about 25 parts by weight, for example, about 30 parts by weight or more). By appropriately adjusting the particle size and content of the filler particles, it is possible to preferably reduce the tensile peeling stress B while suppressing the decrease in the initial adhesive force A. The content of the filler particles with respect to 100 parts by weight of the base polymer is usually about 80 parts by weight or less (for example, about 70 parts by weight or less), preferably about 60 parts by weight or less, and about 55 parts by weight or less (for example). It may be about 50 parts by weight or less).

In one aspect of the pressure-sensitive adhesive sheet disclosed herein, it is appropriate that the content C (volume-based content) of the filler particles in the pressure-sensitive adhesive layer is 30% by volume or less. By appropriately adjusting the particle size and content of the filler particles, the tensile peeling stress B can be preferably reduced while suppressing the decrease in the initial adhesive force A. The content C of the filler particles in the pressure-sensitive adhesive layer is preferably 25% by volume or less, more preferably 20% by volume or less (for example, 16% by volume or less, typically 14% by volume or less). Further, from the viewpoint of reducing tensile peel stress, the content C is appropriately set to 0.3% by volume or more, preferably 2% by volume or more, and more preferably 3% by volume or more (for example, 5% by volume). % Or more, typically 10% by volume or more). Since the technique disclosed herein can exhibit a desired effect by adding a small amount of filler particles, the pressure-sensitive adhesive layer (pressure-sensitive adhesive composition) substantially contains a component (dispersant) that improves the dispersibility of the filler particles. It may not be contained as a target, or the above-mentioned dispersant may be contained. The content C [volume%] of the filler particles is determined based on the weight ratio and density of the components other than the filler particles (typically, the pressure-sensitive component) in the pressure-sensitive adhesive layer and the weight ratio and density of the filler particles. For example, in the examples described later, 2.42 g / cm ³ is adopted as the density of aluminum hydroxide, and the content C [volume%] of the filler particles in the pressure-sensitive adhesive layer can be determined.

(Acrylic oligomer)
The pressure-sensitive adhesive composition disclosed herein may contain an acrylic oligomer. By adopting an acrylic oligomer, impact resistance and repulsion resistance can be improved in a well-balanced manner. Further, in the case where the pressure-sensitive adhesive composition is cured by active energy ray irradiation (for example, UV irradiation), the acrylic oligomer is more curing-inhibited (for example, not yet) than the tack-imparting resin such as rosin-based or terpene-based. It has the advantage that it does not easily cause polymerization inhibition of the reaction monomer. The acrylic oligomer is a polymer containing an acrylic monomer as a constituent monomer component thereof, and is defined as a polymer having a smaller Mw than the acrylic polymer.

The ratio of the acrylic monomer to all the monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, and more preferably 70% by weight or more (for example, 80% by weight). More than 90% by weight or more). In a preferred embodiment, the acrylic oligomer has a monomer composition consisting substantially only of the acrylic monomer.

As the constituent monomer component of the acrylic oligomer, the chain alkyl (meth) acrylate exemplified as the monomer that can be used for the acrylic polymer, the functional group-containing monomer, and other monomers can be used. Further, the constituent monomer may contain an alicyclic hydrocarbon group-containing (meth) acrylate. As the monomer component constituting the acrylic oligomer, one or more of the various monomers exemplified above can be used.

As the chain alkyl (meth) acrylate, an alkyl (meth) acrylate in which R ² is C _1-12 (for example, C _1-8 ) in the above formula (1) is preferably used. Preferable examples thereof include methyl methacrylate (MMA), ethyl acrylate, n-butyl acrylate (BA), isobutyl methacrylate, t-butyl acrylate, and 2-ethylhexyl acrylate (2EHA). Of these, MMA is more preferable.

A preferred example of the functional group-containing monomer is a monomer having a nitrogen atom-containing ring (typically a nitrogen atom-containing heterocycle) such as N-vinyl-2-pyrrolidone and N-acryloylmorpholin; N, N-dimethylamino. Examples thereof include amino group-containing monomers such as ethyl (meth) acrylate; amide group-containing monomers such as N, N-diethyl (meth) acrylamide; carboxy group-containing monomers such as AA and MAA; and hydroxyl group-containing monomers such as HEA.

The alicyclic hydrocarbon group-containing (meth) acrylate is, for example, one kind of alicyclic hydrocarbon group-containing (meth) acrylate in which the number of carbon atoms of the alicyclic hydrocarbon group is in the range of 4 to 20. Alternatively, two or more types can be used. The number of carbon atoms of the alicyclic hydrocarbon group is preferably 5 or more (for example, 6 or more, typically 8 or more), and preferably 16 or less (for example, 12 or less, typically 10 or less). is there. Preferable examples of the alicyclic hydrocarbon group-containing (meth) acrylate include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. Of these, dicyclopentanyl methacrylate (DCPMA) is more preferred.

The ratio (that is, copolymerization ratio) of the alicyclic hydrocarbon group-containing (meth) acrylate to all the monomer components constituting the acrylic oligomer is about 30 to 90% by weight (that is, from the viewpoint of adhesiveness and cohesiveness). For example, it is preferably 50 to 80% by weight, typically 55 to 70% by weight).

In a preferred embodiment, the acrylic oligomer comprises a chain alkyl (meth) acrylate and / or an alicyclic hydrocarbon group-containing (meth) acrylate as its constituent monomer components. In this embodiment, the ratio of the chain alkyl group-containing and alicyclic hydrocarbon group-containing (meth) acrylic acid ester to all the monomer components constituting the acrylic oligomer is approximately 80% by weight or more (for example, 90 to 100). It is preferably% by weight, typically 95 to 100% by weight). It is more preferable that the monomer component constituting the acrylic oligomer is substantially composed of a chain alkyl (meth) acrylate and / or an alicyclic hydrocarbon group-containing (meth) acrylate.

When the acrylic oligomer is a copolymer of a monomer mixture containing a chain alkyl (meth) acrylate and an alicyclic hydrocarbon group-containing (meth) acrylate, the chain alkyl (meth) acrylate and the alicyclic hydrocarbon The ratio with the group-containing (meth) acrylate is not particularly limited. In one preferred embodiment, the weight ratio of the weight percentage of the chain alkyl (meth) weight ratio of acrylate (W _A) and the alicyclic hydrocarbon group-containing (meth) acrylate in the constituent monomer components of the acrylic oligomer (W _{B) (W} a: _{W B)} is 1: 9 to 9: 1, preferably 2: 8-7: 3 (e.g., 3: 7-6: 4, typically 3: 7-5: 5) Is.

Although not particularly limited, the composition of the constituent monomer components of the acrylic oligomer (that is, the polymerization composition) can be set so that the Tg of the acrylic oligomer is 10 ° C. or higher and 300 ° C. or lower. Here, the Tg of the acrylic oligomer means a value obtained in the same manner as the Tg based on the constituent monomer composition of the acrylic polymer based on the composition of the constituent monomer components of the acrylic oligomer. The Tg of the acrylic oligomer is preferably 180 ° C. or lower (for example, 160 ° C. or lower) from the viewpoint of initial adhesiveness. Further, the Tg is preferably 60 ° C. or higher (for example, 100 ° C. or higher, typically 120 ° C. or higher) from the viewpoint of cohesiveness of the pressure-sensitive adhesive.

The Mw of the acrylic oligomer is not particularly limited, but is typically about 0.1 × 10 ^{4 to} 3 × 10 ⁴ . From the viewpoint of improving the adhesive properties (e.g., adhesive strength and repulsion resistance), Mw of the acrylic oligomer is preferably 1.5 × 10 ⁴ or less, more preferably 1 × 10 ⁴ or less, 0.8 × 10 ⁴ or less (e.g. 0.6 × 10 ⁴ or less) are more preferred. From the viewpoint of cohesiveness, etc. of the adhesive, the Mw is, 0.2 × 10 ⁴ or more (e.g., 0.3 × 10 ⁴ or more) are preferred. The molecular weight of the acrylic oligomer can be adjusted by using a chain transfer agent or the like, if necessary, during polymerization.

Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method and the polymerization mode are not particularly limited, and various conventionally known polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be adopted in an appropriate manner. Since the types and amounts of polymerization initiators (for example, azo-based polymerization initiators such as AIBN) that can be used as needed are generally as described above, the description will not be repeated here.

It is appropriate that the content of the acrylic oligomer in the pressure-sensitive adhesive composition disclosed herein is, for example, 0.5 parts by weight or more with respect to 100 parts by weight of the acrylic polymer. From the viewpoint of better exerting the effect of the acrylic oligomer, the content of the acrylic oligomer is preferably 1 part by weight or more (for example, 1.5 parts by weight or more, typically 2 parts by weight or more). .. Further, from the viewpoint of curability of the pressure-sensitive adhesive composition, compatibility with the acrylic polymer, and the like, it is appropriate that the content of the acrylic oligomer is less than 50 parts by weight (for example, less than 10 parts by weight). It is preferably less than 8 parts by weight (for example, less than 7 parts by weight, typically 5 parts by weight or less). Even with such a small amount of addition, improvement in impact resistance and repulsion resistance by using an acrylic oligomer can be realized.

(Adhesive imparting agent)
The pressure-sensitive adhesive layer disclosed herein may have a composition containing a pressure-sensitive adhesive. The tackifier is not particularly limited, and for example, a rosin-based tackifier resin, a terpene-based tackifier resin, a hydrocarbon-based tackifier resin, an epoxy-based tackifier resin, a polyamide-based tackifier resin, and an elastomer-based tackifier resin, Various tackifier resins such as phenol-based tackifier resins and ketone-based tackifier resins can be used. As such a tackifier resin, one type can be used alone or two or more types can be used in combination.

Specific examples of the rosin-based tackifier resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; modified rosins obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc. Hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosin, etc. The same shall apply hereinafter); Other various rosin derivatives; etc. Examples of the above-mentioned rosin derivatives include rosins obtained by esterifying unmodified rosin with alcohols (that is, esterified rosin) and esterifying modified rosin with alcohols (that is, esterified rosin). Esters; Unmodified rosins and unsaturated fatty acid-modified rosins obtained by modifying modified rosins with unsaturated fatty acids; Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Unmodified rosins, modified rosins, unsaturated Rosin alcohols obtained by reducing the carboxy group in fatty acid-modified rosins or unsaturated fatty acid-modified rosin esters; metal salts of rosins (particularly rosin esters) such as unmodified rosins, modified rosins, and various rosin derivatives; rosins. Examples thereof include a rosin phenol resin obtained by adding phenol to (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing the mixture. When an acrylic polymer is used as the base polymer, it is preferable to use a rosin-based tackifier resin. From the viewpoint of improving adhesive properties such as adhesive strength, one of the above rosin-based tackifying resins may be selected alone, or two or three or more having different types and characteristics (for example, softening points) may be used in combination. It is more preferable to do so.

Examples of terpene-based tackifier resins are terpene resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer; these terpene resins are modified (phenolic modification, aromatic modification, hydrogenation modification, hydrocarbons). Modified terpene resin (modified, etc.); etc. Examples of the modified terpene resin include terpene-modified phenolic resin, styrene-modified terpene resin, aromatic-modified terpene resin, hydrogenated terpene resin and the like. When an acrylic polymer is used as the base polymer, it is preferable to use a terpene-based tackifier resin (for example, a terpene-modified phenolic resin). In particular, from the viewpoint of improving adhesive properties such as adhesive strength, one or more of the above terpene-based tackifying resins (for example, terpene-modified phenolic resins) having different types and characteristics (for example, softening points) are used in combination. Is preferable.

Examples of hydrocarbon-based tackifier resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.) ), Various hydrocarbon-based resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, kumaron-based resins, and kumaron-inden-based resins.

In the technique disclosed herein, as the tackifier resin, a resin having a softening point (softening temperature) of about 70 ° C. or higher (preferably about 100 ° C. or higher, more preferably about 110 ° C. or higher) can be preferably used. According to the pressure-sensitive adhesive containing the pressure-sensitive adhesive resin having a softening point equal to or higher than the above-mentioned lower limit value, a pressure-sensitive adhesive sheet having more excellent adhesive strength can be realized. Among the tackifier resins exemplified above, terpene-based tackifier resins having the above softening points (for example, terpene-modified phenolic resin), rosin-based tackifier resins (for example, esterified products of polymerized rosin) and the like can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited, and can be, for example, about 200 ° C. or lower (typically about 180 ° C. or lower). The softening point of the tackifier resin referred to here is defined as a value measured by the softening point test method (ring ball method) specified in any of JIS K 5902 and JIS K 2207.

The amount of the tackifier used is not particularly limited, and can be appropriately set according to the desired adhesive performance (adhesive strength, etc.). For example, based on the solid content, the tackifier is used in a ratio of about 10 to 100 parts by weight (more preferably 20 to 80 parts by weight, still more preferably 30 to 60 parts by weight) with respect to 100 parts by weight of the acrylic polymer. It is preferable to do so. The technique disclosed herein may be carried out in the form of providing a pressure-sensitive adhesive layer substantially free of the pressure-sensitive adhesive.

When the pressure-sensitive adhesive layer is composed of a rubber-based pressure-sensitive adhesive, the rubber-based pressure-sensitive adhesive preferably contains a high-softening point resin having a softening point of 120 ° C. or higher as the tackifying resin. The pressure-sensitive adhesive sheet of this aspect is preferable from the viewpoint of repulsion resistance, holding power and the like. In a preferred embodiment, the high softening point resin may include a tackifier resin having a softening point of 125 ° C. or higher (more preferably 130 ° C. or higher, still more preferably 135 ° C. or higher, for example 140 ° C. or higher). From the viewpoint of adhesive strength to the adherend, the softening point of the high softening point resin is usually 200 ° C. or lower, preferably 180 ° C. or lower, more preferably 170 ° C. or lower (for example, 160 ° C. or lower). ).

As the high softening point resin, a terpene phenol resin, a polymerized rosin, an esterified product of a polymerized rosin, or the like can be preferably adopted. These high softening point resins may be used alone or in combination of two or more. As a preferred embodiment, there is an embodiment in which the high softening point resin contains one kind or two or more kinds of terpene phenol resins. For example, a terpene phenol resin having a softening point of 120 ° C. or higher and 200 ° C. or lower (typically 120 ° C. or higher and 180 ° C. or lower, for example, 125 ° C. or higher and 170 ° C. or lower) can be preferably adopted.

The terpene phenol resin preferably has a softening point of 120 ° C. or higher and a hydroxyl value (OH value) of 40 mgKOH / g or more (typically 40 to 200 mgKOH / g, for example 40 to 160 mgKOH / g). Can be adopted. According to the terpene phenol resin having such a hydroxyl value, a higher performance pressure-sensitive adhesive sheet can be realized. As the value of the hydroxyl value in this specification, a value measured by the potentiometric titration method specified in JIS K 0070: 1992 can be adopted. As a specific measurement method, the method described in JP-A-2014-55235 is adopted.

The techniques disclosed herein are, for example, that the rubber-based pressure-sensitive adhesive has a high softening point resin (H1) having a hydroxyl value of 40 mgKOH / g or more and less than 80 mgKOH / g, and a hydroxyl value of 80 mgKOH / g or more (typically 80 to 80 to It can be preferably carried out in a mode containing 160 mgKOH / g, for example 80 to 140 mgKOH / g) in combination with a high softening point resin (H2). In this case, the relationship between the amounts of the high softening point resin (H1) and the high softening point resin (H2) used is, for example, such that the weight ratio (H1: H2) is in the range of 1: 5 to 5: 1. It can be set to, and it is usually appropriate to set it in the range of 1: 3 to 3: 1 (for example, 1: 2 to 2: 1). As a preferred embodiment, there is an embodiment in which both the high softening point resin (H1) and the high softening point resin (H2) are terpene phenolic resins.

From the viewpoint of repulsion resistance, holding power, etc., the content of the high softening point resin can be, for example, 20 parts by weight or more, and 30 parts by weight or more (for example, 35 parts by weight or more) with respect to 100 parts by weight of the base polymer. ) Is preferable. From the viewpoint of adhesive strength, low temperature characteristics, etc., the content of the high softening point resin with respect to 100 parts by weight of the base polymer is usually preferably 100 parts by weight or less, preferably 80 parts by weight or less, more preferably. Is 70 parts by weight or less. The content of the high softening point resin may be 60 parts by weight or less (for example, 50 parts by weight or less).

The technique disclosed herein is an embodiment in which the rubber-based pressure-sensitive adhesive contains a low softening point resin having a softening point of less than 120 ° C. in place of the high softening point resin or in addition to the high softening point resin. Can be carried out. As a preferred embodiment, the rubber-based pressure-sensitive adhesive contains a high softening point resin having a softening point of 120 ° C. or higher and a low softening point resin having a softening point of less than 120 ° C.

As the low softening point resin, those having a softening point of, for example, 40 ° C. or higher (typically 60 ° C. or higher) can be used. From the viewpoint of repulsion resistance, holding power and the like, those having a softening point of 80 ° C. or higher (more preferably 100 ° C. or higher) and lower than 120 ° C. can be preferably adopted. A low softening point resin having a softening point of 110 ° C. or higher and lower than 120 ° C. may be used.

The technique disclosed herein can be preferably carried out in a manner in which the rubber-based pressure-sensitive adhesive contains at least one of a petroleum resin and a terpene resin (typically an unmodified terpene resin) as the low softening point resin. For example, the main component of the low softening point resin (that is, the component accounting for more than 50% by weight of the low softening point resin) is a composition of petroleum resin, a composition of terpene resin, or a combination of petroleum resin and terpene resin. A certain composition, etc. can be preferably adopted. From the viewpoint of adhesive strength and compatibility, it is preferable that the main component of the low softening point resin is a terpene resin (for example, β-pinene polymer). Substantially all of the low softening point resin (for example, 95% by weight or more) may be a terpene resin.

In a preferred embodiment, the low softening point resin may be a tackifier resin having a hydroxyl value of 0 or more and less than 80 mgKOH / g (low hydroxyl value tackifier resin). As the low hydroxyl value tackifier resin, among the various tackifier resins described above, those having a hydroxyl value in the above range can be used alone or in combination as appropriate. For example, a terpene phenol resin having a hydroxyl value of 0 or more and less than 80 mgKOH / g, a petroleum resin (for example, C5-based petroleum resin), a terpene resin (for example, β-pinene polymer), a rosin-based resin (for example, polymerized rosin), and rosin. A derivative resin (for example, an esterified product of polymerized rosin) or the like can be used.

From the viewpoint of adhesive strength to the adherend, the content of the low softening point resin can be, for example, 10 parts by weight or more, and usually 15 parts by weight or more (for example, 20 parts by weight) with respect to 100 parts by weight of the base polymer. (Above) is appropriate. From the viewpoint of repulsion resistance and the like, it is usually appropriate that the content of the low softening point resin is 120 parts by weight or less, preferably 90 parts by weight or less, and more preferably 70 parts by weight or less (for example, 60 parts by weight). (By weight or less). The content of the low softening point resin may be 50 parts by weight or less (for example, 40 parts by weight or less).

When the tackifier resin contains a low softening point resin and a high softening point resin, the relationship between the amounts used thereof is such that the weight ratio of the low softening point resin: the high softening point resin is 1: 5 to 3: 1 (more preferable). Is preferably set to 1: 5 to 2: 1). The technique disclosed herein is an embodiment in which the rubber-based pressure-sensitive adhesive contains a larger amount of a high softening point resin as a tackifier resin than a low softening point resin (for example, a weight ratio of a low softening point resin: a high softening point resin is 1). : 1.2 to 1: 5) can be preferably carried out. According to such an aspect, a higher performance adhesive sheet can be realized.

In the technique disclosed herein, the content of the tackifier resin with respect to 100 parts by weight of the base polymer (typically a rubber-based polymer) is usually 20 parts by weight or more, preferably 30 parts by weight. As mentioned above, it is more preferably 40 parts by weight or more (for example, 50 parts by weight or more). Further, from the viewpoint of low temperature characteristics (for example, adhesive strength and impact resistance under low temperature conditions), it is usually appropriate that the content of the tackifier resin with respect to 100 parts by weight of the base polymer is 200 parts by weight or less. It is preferably 150 parts by weight or less. The content of the tackifier resin with respect to 100 parts by weight of the base polymer may be 100 parts by weight or less (for example, 80 parts by weight or less).

(Crosslinking agent)
The pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer disclosed herein may contain a cross-linking agent, if necessary. The type of the cross-linking agent is not particularly limited, and a conventionally known cross-linking agent can be appropriately selected and used. Examples of such a cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, metal chelate-based cross-linking agents, and the like. Be done. The cross-linking agent may be used alone or in combination of two or more. Among them, from the viewpoint of improving the cohesive force, it is preferable to use an isocyanate-based cross-linking agent and an epoxy-based cross-linking agent, and an isocyanate-based cross-linking agent is more preferable.

The amount of the cross-linking agent used is not particularly limited, and is, for example, about 10 parts by weight or less (for example, about 0.005 to 10 parts by weight, preferably about 0.01 to 0.01 parts by weight) with respect to 100 parts by weight of the base polymer (for example, acrylic polymer). It can be selected from the range of 5 parts by weight). Since the technique disclosed herein can achieve the desired tensile peeling stress B without reducing the amount of the cross-linking agent used, the amount of the cross-linking agent used is approximately 0 with respect to 100 parts by weight of the acrylic polymer. It may be 1 part by weight or more (for example, 0.8 parts by weight or more, typically 1.2 parts by weight or more). Further, from the viewpoint of limiting the cohesive force and reducing the tensile peeling stress B, the amount of the cross-linking agent used is about 5 parts by weight or less (for example, 3 parts by weight or less, typically 3 parts by weight or less) with respect to 100 parts by weight of the acrylic polymer. May be 2.5 parts by weight or less).

(Other ingredients)
The above-mentioned pressure-sensitive adhesive composition may be used as a leveling agent, a cross-linking aid, a plasticizer, a softening agent, a coloring agent (dye, pigment), an antioxidant, an antioxidant, an ultraviolet absorber, an antioxidant, and light. It may contain various additives that are common in the field of pressure-sensitive adhesive compositions, such as stabilizers and dispersants. Further, for example, an adhesive force adjusting agent such as a silicone-based oligomer may be added to the pressure-sensitive adhesive composition (typically an acrylic pressure-sensitive adhesive composition). As for such various additives, conventionally known ones can be used by a conventional method and do not particularly characterize the present invention, and thus detailed description thereof will be omitted.

(Adhesive composition)
The pressure-sensitive adhesive layer disclosed herein may be a pressure-sensitive adhesive layer formed from a water-based pressure-sensitive adhesive composition, a solvent-type pressure-sensitive adhesive composition, a hot-melt type pressure-sensitive adhesive composition, and an active energy ray-curable pressure-sensitive adhesive composition. .. The water-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in which a pressure-sensitive adhesive (sticking agent layer-forming component) is contained in a solvent containing water as a main component (water-based solvent), and is typically water-dispersed. A type pressure-sensitive adhesive composition (a composition in which at least a part of the pressure-sensitive adhesive is dispersed in water) and the like are included. Further, the solvent-type pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in the form of containing a pressure-sensitive adhesive in an organic solvent. The technique disclosed herein is preferably carried out in a mode in which a pressure-sensitive adhesive layer formed from a solvent-type pressure-sensitive adhesive composition is provided from the viewpoint of preferably realizing adhesive properties such as adhesive strength.

(Method of forming the adhesive layer)
The pressure-sensitive adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to a peelable surface (peeling surface) and drying it can be adopted. Alternatively, a method (direct method) of forming the pressure-sensitive adhesive layer by directly applying (typically applying) the pressure-sensitive adhesive composition to the film-like substrate and drying it can be adopted. Further, a method (transfer) in which a pressure-sensitive adhesive composition is applied to a peelable surface (peeling surface) and dried to form a pressure-sensitive adhesive layer on the surface, and the pressure-sensitive adhesive layer is transferred to a film-like substrate (transfer). Law) may be adopted. As the peeling surface, the surface of the peeling liner, the back surface of the base material that has been peeled off, or the like can be used. The pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to such a form, and may have a regular or random pattern such as a dot shape or a striped shape. It may be a formed pressure-sensitive adhesive layer.

The pressure-sensitive adhesive composition can be applied using a conventionally known coater such as a gravure roll coater, a die coater, or a bar coater. Alternatively, the pressure-sensitive adhesive composition may be applied by impregnation, a curtain coating method, or the like. Further, the drying of the pressure-sensitive adhesive composition is preferably carried out under heating from the viewpoint of promoting the cross-linking reaction and improving the production efficiency. The drying temperature can be, for example, about 40 to 150 ° C. (preferably about 60 to 130 ° C.). After the pressure-sensitive adhesive composition is dried, even if aging is performed for the purpose of adjusting the component transfer in the pressure-sensitive adhesive layer, proceeding with the cross-linking reaction, alleviating the strain that may exist in the base material or the pressure-sensitive adhesive layer, etc. Good.

(Thickness of adhesive layer)
The thickness of the pressure-sensitive adhesive layer disclosed herein is not particularly limited, and can be appropriately selected depending on the intended purpose. Usually, the thickness of the pressure-sensitive adhesive layer is preferably about 3 μm or more, preferably about 5 μm or more, more preferably about 8 μm or more, and further preferably about 15 μm from the viewpoint of productivity such as drying efficiency and adhesive performance. That is all. The thickness of the pressure-sensitive adhesive layer is usually about 100 μm or less, preferably about 70 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, for example, about 35 μm or less. In one aspect, the thickness of the pressure-sensitive adhesive layer may be approximately 30 μm or less, and further may be approximately 25 μm or less. In the case of a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the film-like substrate, the thickness of each pressure-sensitive adhesive layer may be the same or different.

<Film-like base material>
In the pressure-sensitive adhesive sheet having a film-like base material, the film-like base material preferably exhibits a breaking strength of 3 MPa or more. By using the film-like base material exhibiting the above-mentioned breaking strength, the pressure-sensitive adhesive sheet is less likely to be torn and can exhibit excellent tensile removability. In a preferred embodiment, the breaking strength may be about 5 MPa or more (for example, about 6 MPa or more), and further may be about 7 MPa or more (for example, about 8 MPa or more). The upper limit of breaking strength is not particularly limited. Usually, from the viewpoint of elasticity and extensibility of the film-like substrate, the breaking strength is preferably about 100 MPa or less (for example, 90 MPa or less, typically 80 MPa or less). Further, since the pressure-sensitive adhesive sheet disclosed herein can be tensile-peeled even by a low stress, a film-like substrate having a breaking strength of about 30 MPa or less (further, about 20 MPa or less, for example, about 15 MPa or less) may be used. It can be preferably carried out. The breaking strength is measured by the same method as in the case of the adhesive sheet. The same method is adopted for the examples described later. The breaking strength of the film-like base material can be adjusted, for example, by selecting the base material type (selection of the blending ratio of the hard component and the soft component, etc.), the molding method, and the like.

The film-like substrate used for the pressure-sensitive adhesive sheet disclosed herein preferably exhibits an elongation at break of approximately 300% or more. The base material exhibiting elongation at break stretches with respect to tension when the pressure-sensitive adhesive sheet is removed. Due to this elongation, the adhesive sheet is deformed and peeled off from the adherend. In this way, the tension and the deformation of the base material interact with each other to further improve the tensile removability of the pressure-sensitive adhesive sheet. The elongation at break is more preferably about 400% or more (for example, about 450% or more, typically about 500% or more). The upper limit of the elongation at break is not particularly limited. From the viewpoint of workability for removing the pressure-sensitive adhesive sheet, the elongation at break may be, for example, about 1500% or less, or about 1200% or less. The elongation at break is measured by the same method as in the case of the adhesive sheet. The elongation at break of the base material can be adjusted, for example, by selecting the base material type (selecting the blending ratio of the hard component and the soft component, etc.), the molding method, and the like.

The 300% elongation stress S ₃₀₀ of the base material used for the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, but it is usually appropriate that it is less than about 10 MPa (for example, about 7 MPa or less). In a preferred embodiment, the 300% elongation stress S ₃₀₀ of the substrate can be approximately 5 MPa or less (eg, approximately 4 MPa or less). A base material having a lower stress of 300% S ₃₀₀ can be significantly stretched and deformed at a lower stress to reduce the adhesive area of the pressure-sensitive adhesive sheet having the base material. Therefore, it is suitable for reducing the tensile peeling stress B. The lower limit of S ₃₀₀ is not particularly limited, but from the viewpoint of sticking workability of the adhesive sheet, it is usually appropriate to set it to about 0.5 MPa or more (for example, about 1.0 MPa or more), and about 1.5 MPa or more. (For example, about 2.0 MPa or more) may be used. The 300% elongation stress S ₃₀₀ of the base material is measured by the same method as the 300% elongation stress A ₃₀₀ of the pressure-sensitive adhesive sheet using the base material as a test piece. The same method is adopted for the examples described later. The 300% elongation stress S ₃₀₀ of the base material can be adjusted, for example, by selecting the base material type (selection of the blending ratio of the hard component and the soft component, etc.), the molding method, the composition of the base material, and the like.

The 100% elongation stress S ₁₀₀ of the base material is not particularly limited, but is usually preferably less than about 7 MPa (for example, about 5 MPa or less), and preferably about 4 MPa or less (for example, about 3.5 MPa or less). .. Such a base material exhibiting 100% tensile stress S ₁₀₀ is suitable for constructing an adhesive sheet having a low tensile peeling stress B. The lower limit of S ₁₀₀ is not particularly limited, but from the viewpoint of sticking workability and the like, it is usually appropriate to set it to about 0.5 MPa or more (for example, about 1.0 MPa or more). The 100% elongation stress S ₁₀₀ of the base material is measured by the same method as the 100% elongation stress A ₁₀₀ of the pressure-sensitive adhesive sheet using the base material as a test piece. The same method is adopted for the examples described later. 100% tensile stress S ₁₀₀ of the base material, it is possible to adjust the substrate material species selection and molding method, the configuration of the substrate.

As the base material of the pressure-sensitive adhesive sheet disclosed herein, one in which the 300% elongation stress S ₃₀₀ of the base material is approximately 1.5 times or less of the 100% elongation stress S ₁₀₀ can be preferably adopted. That is, a film-like base material in which S ₃₀₀ / S ₁₀₀ is about 1.5 or less is preferable. Such a base material can be significantly stretched and deformed while suppressing an increase in stretch stress due to an increase in the degree of stretch. Therefore, it is suitable for reducing the tensile peeling stress B. In a more preferred embodiment, S ₃₀₀ / S ₁₀₀ can be approximately 1.3 or less (and even approximately 1.2 or less). S ₃₀₀ / S ₁₀₀ may be approximately 1.1 or less. The lower limit of S ₃₀₀ / S ₁₀₀ is not particularly limited, but is usually about 0.5 or more, and typically about 0.8 or more (for example, about 0.9 or more). The S ₃₀₀ / S ₁₀₀ can be adjusted by appropriately adjusting one or both of the S ₁₀₀ and the S ₃₀₀ .

As the base material of the pressure-sensitive adhesive sheet disclosed herein, those having a 25% elongation stress S ₂₅ of about 7 MPa or less (more preferably about 5 MPa or less, for example, about 3 MPa or less) can be preferably used. According to a low film-form substrate of more 25% elongation stress S _25, when removed from the adherend by causing parallel elongation by pulling the adhesive sheet comprising a base material, pulling the start resistance becomes smaller, the tensile Detachability tends to improve. Further, from the viewpoint of sticking workability of the pressure-sensitive adhesive sheet, the 25% elongation stress S ₂₅ of the base material is usually preferably about 0.5 MPa or more (for example, about 1.0 MPa or more). In a preferred embodiment, a substrate having a 25% elongation stress S ₂₅ of about 1.5 MPa or more (for example, about 1.8 MPa or more) can be used. As described above, the fact that the 25% elongation stress S ₂₅ is not too low can be advantageous in terms of workability and shape stability. The 25% elongation stress S ₂₅ of the base material is measured by the same method as the 25% elongation stress A ₂₅ of the pressure-sensitive adhesive sheet using the base material as a test piece. The same method is adopted for the examples described later. 25% elongation stress S ₂₅ of the base material, it is possible to adjust the substrate material species selection and molding method, the configuration of the substrate.

In a preferred embodiment, a substrate in which the 100% elongation stress S ₁₀₀ is approximately 2.5 times or less the 25% elongation stress S ₂₅ can be preferably adopted. That is, a film-like base material in which S ₁₀₀ / S ₂₅ is about 2.5 or less is preferable. Such a base material can be significantly stretched and deformed while suppressing an increase in stretch stress due to an increase in the degree of stretch. Therefore, it is suitable for reducing the tensile peeling stress B. In a more preferred embodiment, S ₁₀₀ / S ₂₅ can be approximately 2.2 or less (and even approximately 2.0 or less, such as approximately 1.7 or less). S ₁₀₀ / S ₂₅ may be approximately 1.5 or less. The lower limit of S ₁₀₀ / S ₂₅ is not particularly limited, but is usually about 0.5 or more, and about 0.8 or more (for example, about 0.9 or more) is appropriate. S ₁₀₀ / S ₂₅ can be adjusted by appropriately adjusting one or both of S ₂₅ and S ₁₀₀ .

The tensile recovery rate of the film-like substrate disclosed herein is not particularly limited. From the viewpoint of preventing tearing and improving workability, it is usually appropriate that the tensile recovery rate is about 10% or more (for example, about 25% or more), and preferably more than 50%. The tensile recovery rate may be substantially 100%, may be about 95% or less, and may be about 90% or less (for example, about 85% or less). In a preferred embodiment, the tensile recovery rate of the film substrate can be approximately 80% or less (eg, approximately 70% or less). By using a base material exhibiting such a tensile recovery rate, it is possible to prevent or reduce the phenomenon that the adhesive sheet peeled off from the adherend due to the tensile peeling hits the operator's hand or the like. The tensile recovery rate of the film-like substrate is measured in the same manner as the tensile recovery rate of the pressure-sensitive adhesive sheet. The tensile recovery rate can be adjusted, for example, by selecting the base material type.

Each property of the base material disclosed herein (for example, S ₂₅ , S ₁₀₀ , S ₃₀₀ , breaking strength, elongation at break, tensile recovery rate, etc.) is applied to at least one direction of the base material. obtain. Similarly, each property of the pressure-sensitive adhesive sheet disclosed herein (eg, A ₂₅ , A ₁₀₀ , A ₃₀₀ , breaking strength, elongation at break, tensile recovery, etc.) applies to at least one direction of the pressure-sensitive adhesive sheet. Can be done. In a preferred embodiment, each of the above properties can be applied to at least the width direction of the substrate or adhesive sheet (direction orthogonal to the machine direction (MD), that is, Transverse Direction, hereinafter also referred to as "TD"). In the elongated pressure-sensitive adhesive sheet, each of the above characteristics can be applied to at least the elongated direction of the pressure-sensitive adhesive sheet.

Further, in the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and the base material, generally, in the measurement of the 300% elongation stress A ₃₀₀ of the pressure-sensitive adhesive sheet described above, the tensile load [N] at the tensile elongation of 300% of the test piece (adhesive sheet) is applied. The value obtained by dividing by the cross-sectional area [mm ² ] of the base material contained in the test piece can be used as an alternative value of the 300% elongation stress S ₃₀₀ of the base material or at least a practically sufficient approximation value. .. This is because the contribution of the pressure-sensitive adhesive layer to the tensile load [N] of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and the base material is extremely small as compared with the contribution of the base material to the tensile load. .. Similarly, for the 100% elongation stress S _{100 of the} base material and the 25% elongation stress S _{25 of the} base material, the adhesive sheet is used as a test piece, and the tensile load at a predetermined tensile elongation is applied to the cutting of the base material contained in the test piece. The value obtained by dividing by the area can be substituted or approximated.

In the pressure-sensitive adhesive sheet disclosed herein, various film-like base materials can be used as the film-like base material (supporting base material) for supporting (lining) the pressure-sensitive adhesive layer. As the base material, for example, a woven fabric film, a non-woven fabric film, or a resin film can be used. Of these, a resin film is preferable. The resin film may be a non-foaming resin film, a rubber-like film, a foam film, or the like. Of these, non-foaming resin films and rubber-like films are preferable, and non-foaming resin films are more preferable. The non-foamed resin film has substantially no bubbles (voids) that can be a weak point in terms of mechanical strength, and tends to be superior in mechanical strength such as tensile strength as compared with a foam. The non-foamed resin film is also excellent in terms of workability, dimensional stability, thickness accuracy, economy (cost), and the like.

The "resin film" in the present specification is a substantially non-porous film, and is a concept that is distinguished from so-called non-woven fabrics and woven fabrics (that is, a concept excluding non-woven fabrics and woven fabrics). Further, the non-foamed resin film refers to a resin film that has not been intentionally treated to form a foam. Specifically, the non-foamed resin film can be a resin film having a foaming ratio of less than about 1.1 times (for example, less than 1.05 times, typically less than 1.01 times). The non-foamed resin film includes, for example, a soft resin film called soft polyolefin, soft polyurethane, soft polyester, soft polyvinyl chloride and the like.

The thickness of the film-like base material is not particularly limited, and can be appropriately selected depending on the intended purpose. The thickness of the film-like substrate is usually appropriately set to about 10 μm or more, and preferably about 20 μm or more (for example, about 30 μm or more). As a base material that is less likely to tear and has excellent tensile removability, a film-like base material having a thickness of about 40 μm or more (for example, about 45 μm or more) and further about 50 μm or more may be used. Further, the thickness of the film-like base material is usually appropriately set to about 250 μm or less, and more preferably about 200 μm or less (more preferably about 150 μm or less, for example, about 120 μm or less). The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented using a film-like substrate having a thickness of about 100 μm or less (typically less than about 100 μm). A film-like substrate having such a thickness is suitable as a component of an adhesive sheet having a total thickness of about 150 μm or less, for example. In one embodiment, the thickness of the film-like substrate is preferably about 90 μm or less, preferably about 80 μm or less, more preferably about 75 μm or less, still more preferably about 70 μm or less (for example, about 65 μm or less). It may be about 60 μm or less (for example, less than about 60 μm). According to the technique disclosed herein, good tensile removability can be realized even in a configuration using a film-like substrate having such a thickness. Reducing the thickness of the film-like base material is advantageous in terms of thinning, downsizing, weight reduction, resource saving, and the like of the pressure-sensitive adhesive sheet containing the film-like base material. The thickness of the film-like substrate can be preferably applied to the non-foamed resin film substrate.

Preferable examples of the resin material constituting the resin film include polyurethanes such as ether-based polyurethanes, ester-based polyurethanes, and carbonate-based polyurethanes; urethane (meth) acrylate-based polymers; polyethylene (PE), polypropylene (PP), and ethylene-propylene. Polyethylenes such as polymers and ethylene-butene copolymers; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate and polybutylene naphthalate; polycarbonate; and the like can be mentioned. As the polyester, polybutylene terephthalate (PBT), polyethylene naphthalate, and polybutylene naphthalate are more preferable. The resin material is a styrene-based copolymer such as a styrene butadiene copolymer, a styrene isoprene copolymer, a styrene ethylene butylene copolymer, a styrene ethylene propylene copolymer, a styrene butadiene styrene copolymer, and a styrene isoprene styrene copolymer. It may be a coalescence (typically a styrene-based elastomer), an acrylic-based copolymer called acrylic rubber, or a vinyl chloride-based resin (PVC) such as soft polyvinyl chloride. Good. The above resin materials may be used alone or in combination of two or more. The resin material includes what is generally called rubber or thermoplastic elastomer.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, a resin film having an elastomer layer (typically, a non-foamed resin film) can be preferably adopted as the film-like base material. The elastomer layer may contain any suitable resin as long as the effects of the present invention are not impaired. Examples of such resins include olefin-based elastomers and styrene-based elastomers. Preferably, the elastomer layer contains an olefin-based elastomer. When the elastomer layer contains an olefin-based elastomer, a film-like substrate useful as a component of the stretchable pressure-sensitive adhesive sheet disclosed herein can be preferably realized. By using such a base material, for example, it is possible to significantly stretch and deform with low stress to reduce the adhesive area, and an adhesive sheet having both an adhesive function and a tensile removability can be formed.

The content ratio of the olefin-based elastomer in the elastomer layer is typically about 50% by weight or more, and usually preferably about 60% by weight or more (for example, about 65% by weight or more). In one embodiment, the content ratio of the olefin-based elastomer in the elastomer layer may be about 70% by weight or more, about 80% by weight or more, about 90% by weight or more, and further about 95% by weight or more. It may be. Substantially 100% by weight of the elastomer layer may be an olefin-based elastomer.

Non-limiting examples of olefin-based elastomers include olefin block copolymers, olefin random copolymers, ethylene copolymers, propylene copolymers, ethylene olefin block copolymers, bropylene olefin block copolymers, ethylene olefin random copolymers, propylene olefin random copolymers, ethylene propylene random copolymers. Copolymers, ethylene (1-butene) random copolymers, ethylene (1-pentene) olefin block copolymers, ethylene (1-hexene) random copolymers, ethylene (1-heptene) olefin block copolymers, ethylene (1-octene) olefin block copolymers, Ethylene (1-nonen) olefin block copolymer, ethylene (1-decene) olefin block copolymer, propylene ethylene olefin block copolymer, ethylene (α-olefin) copolymer, ethylene (α-olefin) random copolymer, ethylene (α-olefin) block Examples thereof include copolymers and combinations thereof. These can be used alone or in combination of two or more.

Examples of the α-olefin include α-olefins having 2 to 12 carbon atoms. Specific examples of such α-olefins include ethylene, propylene, 1-butene, 4-methyl-1-pentene and the like.

The density of the olefin-based elastomer is preferably 0.830 g / cm ³ or more, more preferably 0.835 g / cm ³ or more, still more preferably 0.840 g / cm ³ or more, for example 0.845 g / cm ³ or more. Can be used. As the olefin-based elastomer, a density of preferably 0.890 g / cm ³ or less, more preferably 0.888 g / cm ³ or less, more preferably 0.886 g / cm ³ or less, for example, 0.885 g / cm ³ or less can be used.

As the olefin-based elastomer, an elastomer having an MFR (melt flow rate) of preferably 1.0 g / 10 minutes or more, more preferably 2.0 g / 10 minutes or more can be used. The MFR of the olefin elastomer is preferably 25.0 g / 10 minutes or less, more preferably 23.0 g / 10 minutes or less, still more preferably 21.0 g / 10 minutes or less, and particularly preferably 20.0 g. Those of 10 minutes or less, for example, 19.0 g / 10 minutes or less can be preferably used. Here, MFR refers to a value obtained by measuring by the A method under the conditions of a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K7210.

Specific examples of suitable olefin-based elastomers include α-olefin-based elastomers. The α-olefin-based elastomer is typically a copolymer of two or more types of α-olefins and has an elastomeric property. Preferred α-olefin-based elastomers include ethylene-based elastomers, propylene-based elastomers, and 1-butene-based elastomers. By adopting any of these α-olefin elastomers as the olefin elastomer, a film-like substrate useful as a component of the stretchable pressure-sensitive adhesive sheet disclosed herein can be preferably realized. Among them, an olefin-based elastomer containing either or both of an ethylene-based elastomer and a propylene-based elastomer is preferable as the α-olefin-based elastomer.
The ethylene-based elastomer typically refers to a copolymer containing ethylene as a main monomer, and may be a copolymer in which the copolymerization ratio of ethylene exceeds 50% by weight. Similarly, the propylene-based elastomer generally refers to a copolymer containing propylene as a main monomer, and may be a copolymer in which the copolymerization ratio of propylene exceeds 50% by weight. The same applies to other α-olefin elastomers.

The α-olefin elastomer can also be obtained as a commercially available product. Such commercially available products include, for example, some of the "Toughmer" (registered trademark) series manufactured by Mitsui Chemicals, Inc. (for example, Toughmer PN-3560, etc.) and "Vistamaxx" manufactured by ExxonMobil. Some of the (registered trademark) series (eg, Vistamax 6202, Vistamax 7010, Vistamax 3000, etc.) can be mentioned. These can be used alone or in combination of two or more.

The α-olefin elastomer is preferably produced using a metallocene catalyst. By adopting an α-olefin-based elastomer produced by using a metallocene catalyst, a film-like substrate useful as a component of the extensible pressure-sensitive adhesive sheet disclosed herein can be preferably realized.

The elastomer layer may contain a non-elastomeric resin in addition to the elastomer (preferably an olefin-based elastomer). By using a non-elastomeric resin, the characteristics of the film-like substrate (for example, 1 or 2 or more of the characteristics such as S ₂₅ , S ₁₀₀ , S ₃₀₀ , breaking strength, elongation at break, tensile recovery rate, etc.) are preferably adjusted. Can be done. The elastomer layer may be, for example, an elastomer layer containing an olefin elastomer and a non-elastomer olefin resin in the same layer (that is, an elastomer layer in which an olefin elastomer and a non-elastomer olefin resin are blended). Here, the non-elastomeric olefin resin means an olefin resin that is not an elastomeric olefin resin. As the non-elastomeric olefin resin, a commercially available product may be used.

Non-limiting examples of non-elastomeric olefin resins include α-olefin homopolymers as described above, two or more α-olefin copolymers, block polypropylene, random polypropylene, one or more. Examples thereof include a copolymer of α-olefin and another vinyl monomer. Examples of the form of copolymerization in the copolymer include a block form and a random form.

Examples of the α-olefin homopolymer include polyethylene (PE), homopolypropylene (PP), poly (1-butene), poly (4-methyl-1-pentene) and the like. Examples of polyethylene (PE) include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE) and the like. The structure of homopolypropylene (PP) may be isotactic, atactic, or syndiotactic. Examples of the copolymer of two or more kinds of α-olefins include ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / propylene / 1-butene copolymer, ethylene and 5 to 5 carbon atoms. Examples thereof include a copolymer containing 12 α-olefins, a copolymer containing propylene and α-olefins having 5 to 12 carbon atoms, and the like. Examples of copolymers of one or more α-olefins and other vinyl monomers include ethylene / vinyl acetate copolymers, ethylene / acrylic acid alkyl ester copolymers, and ethylene / methacrylate alkyl esters. Examples include polymers, ethylene / non-conjugated diene copolymers and the like.

The non-elastomeric olefin resin preferably contains an α-olefin homopolymer, and more preferably contains at least one selected from polyethylene (PE) and homopolypropylene (PP). For example, a non-elastomeric olefin resin containing at least one selected from high density polyethylene (HDPE) and homopolypropylene (PP) can be preferably adopted.

In the elastomer layer containing the non-elastomeric olefin resin, the content ratio of the non-elastomer olefin resin in the elastomer layer is not particularly limited, and may be, for example, about 1% by weight or more, typically about 5% by weight or more. .. In one aspect, the content ratio of the non-elastomeric olefin resin can be about 7% by weight, may be about 10% by weight or more, and further can be about 15% by weight or more (for example, about 20% by weight or more). It may be. By increasing the content, for example, 25% elongation stress of the elastomer layer is improved, capable of thus improving the 25% elongation stress S ₂₅ of the film-form substrate comprising the elastomeric layer. Further, from the viewpoint of making it easy to obtain a film-like base material that is easily stretched and deformed with low stress, it is usually appropriate that the content ratio of the non-elastomeric olefin resin in the elastomer layer is less than about 50% by weight. It is preferably about 40% by weight or less (for example, about 35% by weight or less). In one aspect of the elastomer layer, the content ratio of the non-elastomeric olefin resin may be about 20% by weight or less (for example, about 15% by weight or less), or about 10% by weight or less, and may be about 10% by weight or less. It may be 5% by weight or less. The elastomer layer may be substantially free of the non-elastomeric olefin resin.

The elastomer layer may contain any suitable other components. Such other components include, for example, tackifiers, plasticizers, antioxidants, pigments, dyes, antioxidants, antistatic agents, lubricants, foaming agents, heat stabilizers, light stabilizers, inorganics. Examples include fillers and organic fillers. These may be used alone or in combination of two or more. The content ratio of such other components in the elastomer layer is usually preferably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, still more preferably 2% by weight. Hereinafter, for example, it is 1% by weight or less.

The film-like base material may contain only one such elastomer layer, or may contain two or more layers. In a film-like substrate containing two or more elastomer layers, the composition and properties of the two or more elastomer layers may be the same or different. The film-like substrate may include, for example, two or more elastomeric layers in which one or both of the types of elastomers and the content of non-elastomeric resins differ from each other. The film-like base material according to one embodiment contains an elastomer layer Eh containing a non-elastomer resin (typically an olefin-based non-elastomer resin) and a non-elastomer resin-free or non-elastomer resin content ratio. May include less elastomer layer Es than elastomer layer Eh. By combining the elastomer layer Eh and the elastomer layer Es, the characteristics of the film-like substrate (for example, S ₂₅ , S ₁₀₀ , S ₃₀₀ , one or two or more of the characteristics such as breaking strength, elongation at break, tensile recovery rate, etc.) Can be suitably adjusted. It is preferable that the elastomer layer Eh constitutes at least one surface of the film-like substrate. As a result, the handleability of the film-like base material, blocking resistance, and the like can be improved. The film-like substrate may be a laminated body having a structure in which the elastomer layer Eh is arranged on one side of the elastomer layer Es (Es / Eh), and may be on one side and the other side of the elastomer layer Es, respectively. It may be a laminated body having a structure in which the elastomer layer Eh is arranged (Eh / Es / Eh).

In a film-like base material containing the elastomer layer Es and the elastomer layer Eh (for example, a film-like base material having a (Eh / Es / Eh) structure), the thickness of the elastomer layer Es is usually about 5 μm or more. It is preferably about 10 μm or more, more preferably about 15 μm or more, for example, about 20 μm or more. The thickness of the elastomer layer Es is usually about 120 μm or less (for example, about 100 μm or less), preferably about 80 μm or less, more preferably about 60 μm or less, for example, about 55 μm or less. In one aspect, the thickness of the elastomer layer Es may be about 45 μm or less, about 35 μm or less, and further may be about 30 μm or less.
The thickness of the elastomer layer Eh is not particularly limited, and may be, for example, about 1 μm or more. The thickness of the elastomer layer Eh is usually about 2 μm or more, preferably about 5 μm or more, and more preferably about 8 μm or more. In one aspect, the thickness of the elastomer layer Eh may be approximately 10 μm or more, may be approximately 12 μm or more, and may be approximately 15 μm or more. The thickness of the elastomer layer Eh can be, for example, about 30 μm or less, may be about 25 μm or less, or may be about 20 μm or less. In a film-like substrate containing two or more elastomer layers Eh, the thicknesses of the elastomer layers Eh may be the same or different.

In the film-like substrate containing the elastomer layer Es and the elastomer layer Eh, the ratio of the thickness of the elastomer layer Es to the total thickness of the elastomer layer (that is, the total thickness of the elastomer layer Es and the elastomer layer Eh) is, for example, 5. % Or more, usually 10% or more is suitable, preferably 20% or more, more preferably 25% or more, 30% or more, and even 35% or more. May be good. The ratio of the thickness of the elastomer layer Es to the total thickness of the elastomer layer can be, for example, 95% or less, usually 90% or less is appropriate, preferably 80% or less, and more preferably 70%. It is less than or equal to 60% or less, and may be 50% or less. By setting the ratio of the thickness of the elastomer layer Es to the total thickness of the elastomer layer within the above range, a film-like substrate exhibiting the preferable properties disclosed herein can be preferably realized.

The film-like substrate may be a laminate containing at least one elastomer layer and any other suitable layer. By forming the structure in which the elastomer layer and the other layer are combined in this way, the characteristics of the film-like base material can be suitably adjusted. Combining the elastomer layer with another layer can also help improve the handleability and blocking resistance of the film-like substrate.

A preferred example of the layer laminated with the elastomer layer in the film-like base material is an olefin resin layer. The number of layers of the olefin resin layer is not particularly limited, but usually about 1 to 5 layers are suitable, preferably about 1 to 3 layers, and more preferably 1 layer or 2 layers. When the number of layers of the olefin resin layer is two or more, each of these layers may be the same type of layer, or at least two layers may be different layers. For example, a film-like base material having one olefin resin layer on one side and one on the other side of the elastomer layer is preferable. Further, it is preferable that the olefin-based resin layer constitutes at least one surface of the film-like base material.

The olefin resin layer typically contains a non-elastomeric olefin resin. As the non-elastomeric olefin resin, the same resin as the non-elastomeric olefin resin that can be contained in the elastomer layer can be used. The non-elastomeric olefin resin may be only one kind, or may be a blend or a copolymer of two or more kinds.

The content ratio of the non-elastomeric olefin resin in the olefin resin layer is typically about 50% by weight or more, preferably about 70% by weight or more, and more preferably about 80% by weight or more. The content ratio of the olefin-based elastomer may be about 90% by weight or more, or about 95% by weight or more. Substantially 100% by weight of the olefin resin layer may be a non-elastomeric olefin resin.

The olefin resin layer may contain any suitable other components. Such other components include, for example, mold release agents, ultraviolet absorbers, heat stabilizers, fillers, lubricants, colorants (pigments, dyes, etc.), antioxidants, anti-staining agents, anti-blocking agents. , Foaming agent, polyethyleneimine and the like. They may be used alone or in combination of two or more. The content ratio of such other components in the olefin resin layer is usually preferably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, still more preferably 2. By weight or less, for example, 1% by weight or less.

In a film-like base material containing an elastomer layer (which may be a film-like base material containing another layer in addition to the elastomer layer, for example, an olefin resin layer), the thickness of the elastomer layer (when a plurality of elastomer layers are contained). The total thickness of these elastomer layers, that is, the total thickness of the elastomer layers) is usually about 10 μm or more, preferably about 20 μm or more, more preferably about 30 μm or more, for example, about 40 μm or more. In one embodiment, the thickness of the elastomer layer may be approximately 45 μm or more, and further may be approximately 50 μm or more. The thickness of the elastomer layer is typically about 150 μm or less, and usually about 120 μm or less (for example, about 100 μm or less), preferably about 80 μm or less, more preferably about 80 μm or less. It is 70 μm or less, for example, about 60 μm or less. In one aspect of the film-like substrate (for example, an embodiment including another layer in addition to the elastomer layer), the thickness of the elastomer layer may be about 50 μm or less, about 40 μm or less, and further about 30 μm or less. It may be.

In the film-like substrate including the elastomer layer and the olefin resin layer, the thickness of the olefin resin layer is not particularly limited, and may be, for example, about 1 μm or more. The thickness of the olefin resin layer is usually about 2 μm or more, preferably about 5 μm or more, and more preferably about 8 μm or more. In one embodiment, the thickness of the olefin-based resin layer may be about 10 μm or more, about 12 μm or more, and further may be about 15 μm or more. The thickness of the olefin resin layer can be, for example, about 30 μm or less, may be about 25 μm or less, or may be about 20 μm or less. In the film-like base material containing two or more olefin resin layers, the thickness of the olefin resin layers may be the same or different.

In a film-like base material having an olefin-based resin layer on one side and the other side of the elastomer layer, the ratio of the thickness of the elastomer layer to the total thickness of the film-like base material is not particularly limited. The above ratio can be, for example, 5% or more, usually 10% or more is suitable, preferably 20% or more, more preferably 25% or more, 30% or more, and further. It may be 35% or more. The ratio of the thickness of the elastomer layer to the total thickness of the film-like substrate can be, for example, 95% or less, usually 90% or less is appropriate, preferably 80% or less, and more preferably. It may be 70% or less, 60% or less, and further 50% or less. By setting the ratio of the thickness of the elastomer layer to the total thickness of the film-like substrate within the above range, a film-like substrate exhibiting the preferable properties disclosed herein can be preferably realized.

In another preferred embodiment, the film-like substrate is a polyurethane-based resin film. Here, the polyurethane-based resin film refers to a resin film containing polyurethane as the main component of the resin component (the component having the highest blending ratio, typically a component contained in excess of 50% by weight; the same applies hereinafter). .. A polyurethane-based resin film is typically composed of a material that does not substantially exhibit a yield point, and is a film material that easily realizes an adhesive sheet that exhibits a predetermined breaking strength and elongation, and if necessary, a tensile recovery rate. Is. The polyurethane-based resin film can also realize good physical properties without adding an additive component such as a plasticizer, and thus is also a preferable group in the technique disclosed herein in terms of preventing bleeding out of the additive component. Can be a material.

The proportion of polyurethane in the resin component contained in the polyurethane-based resin film is preferably 70% by weight or more (for example, 80% by weight or more, typically 90% by weight or more and 100% by weight or less). The polyurethane-based resin film disclosed herein may be a film made of a polymer blend of polyurethane and other resins. The other resin may be one or more, for example, an acrylic resin, a polyolefin, a polyester, a polycarbonate, or the like. Alternatively, the technique disclosed herein can also be carried out in an embodiment using a substrate that substantially does not contain a resin component other than polyurethane.

The polyurethane is a polymer compound synthesized by subjecting a polyol (for example, diol) and a polyisocyanate (for example, diisocyanate) to a polyaddition reaction at a predetermined ratio. The NCO / OH ratio of polyurethane may be appropriately set based on the common general technical knowledge of those skilled in the art so as to obtain desired mechanical properties (for example, breaking strength, elongation at breaking, tensile recovery rate).

Examples of the polyol that can be used in the synthesis of the polyurethane include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexane. Diols, 1,8-octanediols, polyoxytetramethylene glycols, diethylene glycols, polyethylene glycols, polypropylene glycols and other diols; polyesters that are polycondensates of the above diols and dicarboxylic acids (eg, adipic acid, azelaic acid, sebacic acid). Polyols; carbonate diols such as polyalkylene carbonate diols; and the like. These can be used alone or in combination of two or more.

Examples of the polyisocyanate that can be used for synthesizing the polyurethane include aromatic, aliphatic, and alicyclic diisocyanates, and multimers (for example, dimersions and trimers) of these diisocyanates. Examples of the diisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, and 1,3-phenylenedi isocyanate. , 1,4-phenylenediocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4 , 4-Diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate and the like. These can be used alone or in combination of two or more. Of these, aromatic diisocyanates are preferable.

In addition to the polyol and polyisocyanate, other copolymerization components may be introduced into the polyurethane. As the other copolymerization component, one or more of monocarboxylic acid, dicarboxylic acid, trifunctional or higher polycarboxylic acid, hydroxycarboxylic acid, alkoxycarboxylic acid, derivatives thereof and the like can be used. It is appropriate that the ratio of these other copolymerization components is less than 30% by weight (for example, less than 10% by weight, typically less than 5% by weight) in polyurethane. The technique disclosed herein can also be preferably carried out in an embodiment including a polyurethane-based resin film base material containing a polyurethane as a main component which does not contain other copolymerization components.

In another preferred embodiment, the film-like substrate is a resin film containing a urethane (meth) acrylate-based polymer. As the urethane (meth) acrylate-based polymer disclosed herein, a polymer containing a structural unit derived from urethane (meth) acrylate can be used. Here, the urethane (meth) acrylate refers to a compound having a urethane bond and a (meth) acryloyl group in one molecule, and such a compound can be used without particular limitation. Urethane (meth) acrylate may be used alone or in combination of two or more. Urethane (meth) acrylates preferably have two or more urethane bonds and two or more (meth) acryloyl groups. The number of (meth) acryloyl groups contained in the urethane (meth) acrylate is preferably 2 to 5, more preferably 2 to 3. For example, urethane (meth) acrylate having two (meth) acryloyl groups may be preferably used. Further, the urethane (meth) acrylate is preferably urethane acrylate. Here, the "urethane acrylate" refers to those in which the number ratio of acryloyl groups exceeds 50% among the (meth) acryloyl groups contained in the urethane (meth) acrylate.

As the urethane (meth) acrylate, various commercially available urethane (meth) acrylates can be used. For example, the product name "UV-3300B" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., the product name "Beam Set 505A-6" manufactured by Arakawa Chemical Industry Co., Ltd., and the like can be preferably used.

In another preferred embodiment, the film-like substrate is a PVC-based resin film. The PVC-based resin film is produced by molding a PVC-based resin composition (molding material) containing a PVC-based resin into a film. Here, the PVC-based resin composition refers to a resin composition in which the main component (that is, 50% by weight or more) of the resin component (polymer component) is a PVC-based resin (typically PVC). It is preferable that about 80% by weight or more (more preferably about 90% by weight or more) of the total amount of the resin component contained in the PVC-based resin composition is the PVC-based resin. Substantially the total amount of the resin component may be PVC. According to such a PVC-based resin composition, a PVC-based resin film exhibiting physical properties suitable as a base material for an adhesive sheet can be formed.

The film-like substrate may have a single-layer structure, or may have a multi-layer structure of two layers, three layers or more. In the case of a multi-layer structure, at least one layer (preferably all layers) is one of the above-mentioned resins (preferably an elastomer such as an olefin-based elastomer, a non-elastomer resin such as a non-elastomeric polyolefin-based resin, polyurethane, urethane. It is preferable that the layer has a continuous structure (any one selected from (meth) acrylate-based polymer and PVC).

For film-like substrates (for example, resin film substrates), if necessary, fillers (inorganic fillers, organic fillers, etc.), colorants (pigments, dyes), antioxidants, antioxidants, UV absorbers, etc. Various additives such as agents, antistatic agents, lubricants, plasticizers, stabilizers and the like may be blended. For example, when a soft PVC resin film is used as the film-like base material, the blending amount of the plasticizer is about 20 to 100 parts by weight (more preferably about 30 to 70 parts by weight) per 100 parts by weight of the PVC resin. Is appropriate. The blending ratio of the various additives is usually less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

The surface of the film-like substrate may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of an undercoat agent. Such a surface treatment may be a treatment for improving the adhesion between the film-like base material and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer on the base material. When the film-like base material is a polyurethane-based resin film, good anchoring property can be obtained even if the above-mentioned surface treatment is not applied due to its high surface energy.

The method for producing the film-like base material may appropriately adopt a conventionally known method, and is not particularly limited. When a resin film base material is used as the film-like base material, it is produced by appropriately adopting a conventionally known general film molding method such as extrusion molding, inflation molding, T die casting molding, or calender roll molding. A resin film base material can be used.

<Adhesive sheet size, etc.>
The total thickness of the pressure-sensitive adhesive sheet (including the pressure-sensitive adhesive layer and the base material, but not the release liner) disclosed herein is not particularly limited. The total thickness of the pressure-sensitive adhesive sheet can be, for example, about 20 μm or more, and usually 30 μm or more is suitable, preferably 40 μm or more, and more preferably 50 μm or more. By setting the total thickness of the pressure-sensitive adhesive sheet to 55 μm or more, further 65 μm or more (for example, 75 μm or more), a pressure-sensitive adhesive sheet that is less likely to tear and has excellent tensile removability tends to be realized. The total thickness of the pressure-sensitive adhesive sheet is usually preferably 300 μm or less, and more preferably 250 μm or less (more preferably 200 μm or less, for example 170 μm or less). In one aspect of the pressure-sensitive adhesive sheet disclosed herein, the total thickness of the pressure-sensitive adhesive sheet is preferably 150 μm or less (typically less than 150 μm), more preferably 130 μm or less, still more preferably 120 μm or less, for example 110 μm or less. .. According to the technique disclosed herein, good tensile removability can be realized even with such a relatively thin adhesive sheet. Making the adhesive sheet thinner is advantageous in terms of thinning, downsizing, weight reduction, resource saving, and the like.

When the pressure-sensitive adhesive sheet disclosed herein has a long shape, the length thereof is preferably 1 cm or more (for example, 3 cm or more, typically 5 cm or more) from the viewpoint of removal workability by tension. From the viewpoint of removal workability, the length of the adhesive sheet is preferably 30 cm or less (for example, 15 cm or less). In the pressure-sensitive adhesive sheet according to one aspect, the length of the pressure-sensitive adhesive sheet may be 10 cm or less (for example, 5 cm or less).

When the pressure-sensitive adhesive sheet disclosed herein has an elongated shape, its width may be about 30 mm or less (for example, 20 mm or less, typically 15 mm or less). For example, when the adhesive sheet is used in a portable electronic device, the above width can be preferably adopted. From the viewpoint of preventing damage such as tearing during tensile removal, the width of the adhesive sheet is preferably 1 mm or more (for example, 3 mm or more, typically 5 mm or more), and 10 mm or more (for example, 12 mm or more). Is more preferable. When the entire adhesive sheet is elongated, the above width is the width of the adhesive sheet.

<Use>
The pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and is, for example, a metal material such as stainless steel (SUS) and aluminum; an inorganic material such as glass and ceramics; nylon, polycarbonate (PC), polymethyl methacrylate (PMMA), and the like. It can be used by being attached to an adherend having a surface made of a resin material such as polypropylene or polyethylene terephthalate (PET); a rubber material such as natural rubber or butyl rubber; and a composite material thereof.

The pressure-sensitive adhesive sheet disclosed herein exhibits a sufficient adhesive function when used, and is excellent in tensile removability when removed. Taking advantage of this feature, it is preferably used as an adhesive sheet for various purposes that can be peeled off again after being attached. For example, for fixing a protective panel (lens) that protects the display part of electronic devices, for fixing a decoration panel of a display (for example, a TV display), for fixing a battery pack of a personal computer, for waterproofing a lens of a digital video camera, etc. The adhesive sheet disclosed herein can be applied. Among them, it can be preferably used as an adhesive sheet for portable electronic devices, which is required to have an adhesive strength of a predetermined value or more at the time of use, and is required to be smoothly removed at the time of repair, replacement, inspection, recycling, etc. of constituent members. For example, mobile phones, smartphones, tablet PCs, laptop PCs, various wearable devices (for example, wristwatch type that is worn on the wrist like a wristwatch, modular type that is worn on a part of the body with a clip or strap, glasses type) (Monocular type and binocular type. Including head mount type. Eyewear type, clothes type attached to shirts, socks, hats, etc. in the form of accessories, earwear type attached to ears like earphones, etc.), Digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), computers (computers, etc.), portable game equipment, electronic dictionaries, electronic notebooks, electronic books, in-vehicle information equipment, portable radios, portable TVs, mobile phones In portable electronic devices such as printers, portable scanners, and portable modems, protective panel (lens) fixing, key module member fixing, rim sheet fixing, decoration panel fixing, battery fixing, and various other members (circuit board, various types) that protect the display unit Preferable for fixing panel members, buttons, lighting equipment members, internal camera members, heat dissipation materials, graphite sheets), fixing display objects (including various marks) such as logos (design letters) and various designs. Can be applied. Since the adhesive sheet disclosed here exhibits an adhesive strength equal to or higher than a predetermined value, when used in the portable electronic device, the adherend member is fixed even against an impact when the portable electronic device is dropped. Can hold the placement. This is particularly advantageous in battery fixing applications. This is because the battery to be fixed can expand over time, so a gap is provided around it, and improper fixing (peeling of the adhesive sheet) due to a drop impact or the like tends to be a significant defect. .. In addition, in this specification, "portable" means that it is not enough to be portable, but that an individual (standard adult) has a level of portability that is relatively easy to carry. It shall mean.

Further, the pressure-sensitive adhesive sheet (typically, a double-sided pressure-sensitive adhesive sheet) disclosed herein is excellent in performance (pull-out removability) of removing the adhesive sheet by pulling it out from between the adherends. Here, the pull-out removability means that a part (typically a tab) of the adhesive sheet is exposed from two adherends fixed via the adhesive sheet, and the exposed portion is pulled to pull the adhesive sheet. It refers to the ease of removal, such as releasing the fixation (typically joining) of the adherend by pulling out. The two adherends can be two parts of one member. Hereinafter, a more specific description will be given with reference to FIGS. 4 and 5.

FIG. 4 is a schematic side view for explaining one aspect of tensile removal (typically pull-out removal), and FIG. 4A is a view showing a state in which tension removal of the adhesive sheet is started. b) is a diagram showing a state in which the adhesive sheet is pulled and removed, and (c) is a diagram showing a state in which the tensile removal of the adhesive sheet is completed. 5A and 5B are schematic top views for explaining one aspect of tensile removal (typically pull-out removal), and FIGS. 5A to 5C are shown in FIGS. 4A to 4C, respectively. It is a corresponding figure.

As shown in FIGS. 4A and 5A, the adhesive sheet (double-sided adhesive sheet) 200 is provided with a tab T that is exposed to the outside when the adherends A and B are joined. There is. The adherend B is joined to the adherend A using the adhesive sheet 200. Then, after achieving the joining purpose, the tab T is pinched with fingers and the adhesive sheet 200 is pulled so as to be pulled out from between the adherends A and B. Then, the adhesive sheet 200 begins to stretch, contracts in the direction orthogonal to the pulling direction, and begins to peel off from the adherends A and B (see (b) in FIG. 4 and (b) in FIG. 5). Finally, the entire adhesive region of the adhesive sheet 200 is peeled off, and the extraction of the adhesive sheet 200 from between the adherends A and B is completed (see (c) in FIG. 4 and (c) in FIG. 5). The removal of the adherend B joined to the adherend A is also completed at the same time.

The adhesive sheet having excellent tensile removability as described above is suitable as an adhesive sheet used for the purpose of fixing a battery (including a primary battery and a secondary battery, for example, a polymer battery) in a portable electronic device. Batteries are usually placed in places that need to be removed when repairing, replacing, or inspecting components (including batteries) of portable electronic devices. Therefore, the adhesive sheet for fixing the battery often needs to be removed. However, removing the battery by using a remover, peeling it off by hand, heating, or other physical means may damage the battery and may not be preferable in terms of safety. Reducing the peeling force by photo-curing is also not effective because the irradiation is performed through the battery due to the application site of the adhesive sheet. The adhesive sheet disclosed herein exerts a function of fixing the battery well, and when removing the battery after the period of use, the above-mentioned tension removal (typically pull-out removal) method is used. , The removal can be done easily. The pressure-sensitive adhesive sheet is particularly preferable as a pressure-sensitive adhesive sheet used for the purpose of fixing a polymer battery. Polymer batteries tend to be more deformable than other types of batteries (typically batteries with metal cases), so traditional peeling methods can deform the battery and impair its functionality. there were. According to the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet can be satisfactorily removed while suppressing the deformation of the polymer battery by utilizing the above-mentioned tension removal (typically pull-out removal) method.

In addition, the adhesive sheet used to fix the battery of a portable battery device is often unable to be pulled parallel to the shearing direction when it is removed due to other parts existing around the battery and the arrangement of the battery. .. In such a case, the adhesive sheet is removed by pulling at an angle non-parallel to the adhesive surface (for example, an angle of 45 degrees or more and 90 degrees or less, typically 70 degrees or more and less than 90 degrees). At the time of removal, there was a risk of damage due to contact with an adherend (battery) or an obstacle. According to the technique disclosed herein, the pressure-sensitive adhesive sheet can be preferably removed without damaging it even in such a removal mode.

Further, the adhesive sheet having excellent tensile removal property (typically pull-out removal property) is attached to a wall surface, a pillar, furniture, a home electric appliance, a glass surface, etc., and is attached after being used for a predetermined period of time. It is also suitable as an adhesive sheet (typically a double-sided adhesive sheet) used for the purpose of fixing a body (object to be fixed, object to be attached, etc.). Also in this application, the adhesive sheet exerts a good fixing function during fixing of the adherend, and when removing the adherend, the entire adhesive sheet is pulled out by grasping a tab or the like provided on the adhesive sheet. This makes it possible to efficiently remove the adhesive sheet (for example, removal in the direction of the arrow in FIG. 4C).

Matters disclosed by this specification include:
(1) An extensible adhesive sheet provided with an adhesive layer.
The total thickness is about 150 μm or less,
An adhesive sheet having an initial adhesive force A to polycarbonate of 2N / 20 mm or more and a tensile peeling stress B to polycarbonate of 16 N / 20 mm or less.
(2) The pressure-sensitive adhesive sheet according to (1) above, further comprising a film-like base material that supports the pressure-sensitive adhesive layer.
(3) The adhesive sheet according to (2) above, wherein the 300% elongation stress S _{300 of the} film-like substrate is about 5 MPa or less.
(4) The above-mentioned (2) or (3), wherein the 300% elongation stress S ₃₀₀ of the film-like substrate is approximately 1.5 times or less of the 100% elongation stress S ₁₀₀ of the film-like substrate. Adhesive sheet.
(5) The pressure-sensitive adhesive sheet according to any one of (2) to (4) above, wherein the thickness of the film-like base material is about 10 μm or more and about 90 μm or less.
(6) The pressure-sensitive adhesive sheet according to any one of (1) to (5) above, wherein the pressure-sensitive adhesive layer contains filler particles.
(7) The pressure-sensitive adhesive sheet according to (6) above, wherein the average particle size of the filler particles is larger than about 3% and less than about 50% of the thickness of the pressure-sensitive adhesive layer.
(8) The pressure-sensitive adhesive sheet according to (6) or (7) above, wherein the content of the filler particles in the pressure-sensitive adhesive layer is about 12 parts by weight or more and about 60 parts by weight or less with respect to 100 parts by weight of the base polymer. ..
(9) As the pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer provided on the first surface of the film-like base material and a second pressure-sensitive adhesive layer provided on the second surface of the film-like base material are provided. The adhesive sheet according to any one of (2) to (8) above.
(10) It is used to join one object and another object, and by pulling one end of the adhesive sheet in a state where the one object and the other object are joined with the adhesive sheet sandwiched between them. The adhesive sheet according to (9) above, wherein the adhesive sheet is stretched and the joint state between the one object and the other object is released.
(11) The above (1) to (10), wherein the tensile peeling stress B [N / 20 mm] is about 2.0 times or less (for example, about 1.8 times or less) of the initial adhesive force A [N / 20 mm]. ) The adhesive sheet described in any of.
(12) The adhesive sheet according to any one of (1) to (11) above, which is used for fixing a battery of a portable electronic device.

(13) An extensible pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing filler particles and a film-like base material that supports the pressure-sensitive adhesive layer.
The initial adhesive force A to the polycarbonate is 2N / 20 mm or more, and the tensile peeling stress B [N / 20 mm] to the polycarbonate is approximately 2.4 times or less (preferably 2.0 times or less, more preferably 2.0 times or less) the initial adhesive force A. Is about 1.8 times or less, for example, about 1.5 times or less), an adhesive sheet.
(14) The adhesive sheet according to (13) above, wherein the 300% elongation stress S _{300 of the} film-like substrate is about 5 MPa or less.
(15) The above-mentioned (13) or (14), wherein the 300% elongation stress S ₃₀₀ of the film-like substrate is approximately 1.5 times or less of the 100% elongation stress S ₁₀₀ of the film-like substrate. Adhesive sheet.
(16) The average particle size of the filler particles is more than about 3% and less than about 50% (for example, more than about 25% and less than about 50%) of the thickness of the pressure-sensitive adhesive layer. The adhesive sheet according to any one of (15).
(17) The content of the filler particles in the pressure-sensitive adhesive layer is about 12 parts by weight or more (for example, about 15 parts by weight or more and about 60 parts by weight or less) with respect to 100 parts by weight of the base polymer. The adhesive sheet according to any one of (16).
(18) The adhesive sheet according to any one of (13) to (17) above, wherein the total thickness is about 150 μm or less.

(19) An extensible pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing filler particles and a film-like base material that supports the pressure-sensitive adhesive layer.
In the film-like substrate, the 300% elongation stress S ₃₀₀ is about 5 MPa or less, and the 100% elongation stress S ₁₀₀ is about 1.5 times or less of the 300% elongation stress S ₃₀₀ .
The average particle size of the filler particles is more than about 3% and less than about 50% of the thickness of the pressure-sensitive adhesive layer (for example, more than about 25% and less than about 50%).
The content of the filler particles in the pressure-sensitive adhesive layer is about 12 parts by weight or more and about 60 parts by weight or less (for example, about 15 parts by weight or more and about 60 parts by weight or less) with respect to 100 parts by weight of the base polymer. ..
(20) The adhesive sheet according to (19) above, which has a total thickness of about 150 μm or less.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in the examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

<Example 1>
(Preparation of acrylic pressure-sensitive adhesive composition)
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introduction pipe, a reflux cooler, and a dropping funnel, 100 parts of BA, 5 parts of VAc, 3 parts of AA, 0.1 part of HEA, and 0.2 part of AIBN as a polymerization initiator. , Toluene as a polymerization solvent was charged, and solution polymerization was carried out at 60 ° C. for 6 hours to obtain a toluene solution of an acrylic polymer. Mw of the acrylic polymer was 55 × 10 ^4.
For 100 parts of the acrylic polymer (base polymer) contained in the toluene solution, 40 parts of a polymerized rosin ester resin (manufactured by Arakawa Chemical Industry Co., Ltd., product name "Pencel D-125", softening point 125 ° C.) as a tackifier resin. , 2 parts of isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L"), and 30 parts of aluminum hydroxide particles as filler particles (manufactured by Showa Denko Co., Ltd., trade name "Heidilite H-32") And were added and mixed to prepare an acrylic pressure-sensitive adhesive composition. The filler particles have an average particle size of 8 μm, and the proportion of particles having a particle diameter of less than 25 μm is 85% or more, and the proportion of particles having a particle diameter of less than 1 μm is 3%.

(Preparation of film-like substrate)
As the molding material Es, an olefin-based elastomer (“Vistamax (registered trademark) 6202” manufactured by ExxonMobil, Inc. (propylene-based elastomer, ethylene content 15% by weight, MFR 20 g / 10 minutes) was prepared.
As the molding material Eh, a non-elastomer olefin-based molding material is used for 100 parts of an olefin-based elastomer ("Vistamax (registered trademark) 3000" (propylene-based elastomer, ethylene content 11% by weight, MFR 8 g / 10 minutes) manufactured by Exxon Mobile Co., Ltd.). A mixture of 30 parts of HDPE (manufactured by Toso Co., Ltd., trade name "Nipolon Hard 1000") as a resin was prepared.
The molding material Es and the molding material Eh are put into an extrusion molding machine, and the elastomer layer Es based on the molding material Es and the elastomer layer Eh based on the molding material Eh are laminated in an arrangement of (Eh / Es / Eh). By extruding a resin film having a structure, a film-like base material F1 having a thickness of 55 μm was produced. The thickness of the elastomer layers Es constituting the film-like base material F1 was 22 μm, and the thickness of each elastomer layer Eh was 16.5 μm.

(Making a double-sided adhesive sheet)
Two commercially available release liners (trade name "SLB-80W3D", manufactured by Sumika Kako Paper Co., Ltd.) were prepared. The pressure-sensitive adhesive composition was applied to one surface (peeling surface) of each of the release liners so as to have a thickness of 22.5 μm after drying, and dried at 100 ° C. for 2 minutes. In this way, a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer) was formed on the peel-off surfaces of the two release liners, respectively.
Adhesive layers formed on the two release liners were laminated on both sides of the film-like base material F1. The release liner was left as it was on the pressure-sensitive adhesive layer and used to protect the surface (adhesive surface) of the pressure-sensitive adhesive layer. The obtained structure was passed once through a laminator (0.3 MPa, speed 0.5 m / min) at 80 ° C., and then aged in an oven at 50 ° C. for 1 day. In this way, a double-sided adhesive sheet having a total thickness of 100 μm was produced.

<Example 2>
As the film-like base material F2, a non-foamed ether-based polyurethane resin film having a thickness of 60 μm (manufactured by Nihon Matai Co., Ltd., trade name “Esmer URS ET-N”) was prepared.
The same adhesive composition as that used in Example 1 is applied to one surface (peeling surface) of each of the same two release liners used in Example 1 so that the thickness after drying is 20 μm. Then, it was dried at 100 ° C. for 2 minutes. In this way, a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer) was formed on the peel-off surfaces of the two release liners, respectively.
Adhesive layers formed on the two release liners were laminated on both sides of the film-like base material F2. The release liner was left as it was on the pressure-sensitive adhesive layer and used to protect the surface (adhesive surface) of the pressure-sensitive adhesive layer. The obtained structure was passed once through a laminator (0.3 MPa, speed 0.5 m / min) at 80 ° C., and then aged in an oven at 50 ° C. for 1 day. In this way, a double-sided adhesive sheet having a total thickness of 100 μm was produced.

For the double-sided adhesive sheets of Examples 1 and 2, the initial adhesive force A [N / 20 mm], the tensile peeling stress B [N / 20 mm], and the shear adhesive force [MPa] were measured by the above-mentioned methods. At the time of these measurements, no tearing of the adhesive sheet or adhesive residue on the surface of the adherend was observed in any of Examples 1 and 2. Further, with respect to the film-like substrates F1 and F2, 25% elongation stress S ₂₅ [MPa], 100% elongation stress S ₁₀₀ [MPa], 300% elongation stress S ₃₀₀ [MPa] and breaking strength [MPa] by the above method. ] Was measured. The results are shown in Table 1.

As shown in Table 1, according to the adhesive sheet of Example 1, the tensile peeling stress B is significantly increased as compared with the adhesive sheet of Example 2 while maintaining the same good initial adhesive force A as that of the adhesive sheet of Example 2. I was able to reduce it.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

1,200,800 Adhesive sheet 10 Film-like base material 21,22 Adhesive layer 100,800 Measurement sample 100A, 100B, 800A, 800B Adhesive surface 111,112 Polycarbonate plate 801,802 Stainless steel plate

Claims (9)

An extensible adhesive sheet with an adhesive layer,
The pressure-sensitive adhesive layer contains filler particles and
The content of the filler particles in the pressure-sensitive adhesive layer is 12 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the base polymer.
The average particle size of the filler particles is greater than 3% and less than 50% of the thickness of the pressure-sensitive adhesive layer.
Further provided with a film-like base material that supports the pressure-sensitive adhesive layer,
The 300% elongation stress S _{300 of the} film-like substrate is 5 MPa or less.
The film-like substrate is selected from the group consisting of a non-foaming resin film having an elastomer layer, a non-foaming soft polyolefin resin film, a non-foaming polyurethane resin film, and a non-foaming soft polyvinyl chloride resin film.
The total thickness is 150 μm or less,
An adhesive sheet having an initial adhesive force A to polycarbonate of 2N / 20 mm or more and a tensile peeling stress B to polycarbonate of 16 N / 20 mm or less. The pressure-sensitive adhesive sheet according to claim 1, wherein the film-like base material is a non-foamable resin film having the elastomer layer or the non-foamable polyurethane-based resin film. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the film-like base material is a non-foamed resin film having the elastomer layer, and the elastomer layer is an elastomer layer containing an olefin-based elastomer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the 300% elongation stress S ₃₀₀ of the film-like substrate is 1.5 times or less of the 100% elongation stress S ₁₀₀ of the film-like substrate. .. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the film-like substrate has a thickness of 10 μm or more and 90 μm or less. Claimed to include, as the pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer provided on the first surface of the film-like base material and a second pressure-sensitive adhesive layer provided on the second surface of the film-like base material. The adhesive sheet according to any one of Items 1 to 5 . It is used to join one object and another object, and by pulling one end of the adhesive sheet in a state where the one object and the other object are joined with the adhesive sheet sandwiched, the adhesive sheet is released. The adhesive sheet according to claim 6, which stretches and releases the joint state between the one object and the other object. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7 , wherein the tensile peeling stress B [N / 20 mm] is 2.0 times or less the initial pressure-sensitive adhesive force A [N / 20 mm]. The adhesive sheet according to any one of claims 1 to 8 , which is used for fixing a battery of a portable electronic device.

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