KR101994568B1 - Adhesive sheet - Google Patents

Abstract

A pressure-sensitive adhesive sheet which has a pressure-sensitive adhesive layer on one side or both sides of a substrate and which can be peeled off by stretching is characterized in that the substrate is obtained by using a polyurethane resin having a softening point according to JIS K 7196 of 60 ° C or lower as a base polymer (Adhesive) does not remain at the time of peeling by the adhesive sheet and the sheet is not broken.

Description

ADHESIVE SHEET [0002]

The present invention relates to a pressure-sensitive adhesive sheet having a single side or a double-sided pressure-sensitive adhesive sheet which can be peeled off without any residue or breakage by extensive stretching in the adhesive surface.

For example, in a portable electronic device such as a smart phone or a cellular phone, an adhesive sheet is used for fixing the battery pack and the case. When the battery pack is taken out, the adhesive sheet is pulled and peeled by stretching. The pressure-sensitive adhesive sheet in this application is required to have such properties as no residue (adhesive) remains at the time of peeling, no breakage of the sheet, and the like.

As a pressure-sensitive adhesive sheet which can be peeled off by stretching, for example, Patent Document 1 discloses a specific adhesive film piece in which the adhesive property of the adhesive layer is lost when the film is stretched. In Patent Document 2, Patent Document 3 discloses an adhesive sheet strip comprising a styrene block copolymer and an acid-modified and / or acid-anhydride-modified elastomer, Document 4 discloses an adhesive tape having a specific inherent layer (backing layer) and a pressure-sensitive adhesive layer.

However, the pressure-sensitive adhesive sheet which can be peeled off by the conventional stretching has a room for further improvement in performance such that no residue remains at the time of peeling, and further, no breakage of the sheet occurs.

Patent Document 1: Japanese Patent No. 3827247 Patent Document 2: Japanese Patent Application Laid-Open No. 2004-162065 Patent Document 3: JP-A-2003-041217 Patent Document 4: Japanese Patent Laid-Open Publication No. 2012-528919

An object of the present invention is to provide a pressure-sensitive adhesive sheet which does not leave a residue (pressure-sensitive adhesive) on peeling by stretching and does not break the sheet.

The inventors of the present invention have made intensive investigations in order to achieve the above object, and have found that it is very effective to use a specific urethane resin as the base polymer of the base material, and have completed the present invention.

That is, the present invention relates to a pressure-sensitive adhesive sheet which has a pressure-sensitive adhesive layer on one side or both sides of a substrate and which can be peeled off by stretching, wherein the substrate is a polyurethane resin obtained by using a polyurethane resin having a softening point of 60 ° C or less according to JIS K 7196 as a base polymer Sensitive adhesive sheet.

In the present invention, since a specific urethane resin is used as the base polymer of the base material, appropriate flexibility, stretchability and tensile strength are exhibited, and as a result, the base material is not broken even in peeling by stretching, .

<Description>

The substrate used in the present invention is characterized by being obtained by using a polyurethane resin having a softening point of 60 캜 or lower as a base polymer. Specifically, the softening point measured according to JIS K 7196 &quot; Softening temperature test method of thermoplastic plastic film and sheet by thermomechanical analysis &quot; is 60 ° C or lower, preferably 30 ° C to 60 ° C. By using a polyurethane resin having a relatively low softening point as described above, suitable flexibility, stretchability, and tensile strength are exhibited on the substrate, and as a result, the substrate is not broken even when peeling by stretching, and the pressure-sensitive adhesive sheet is excellent in reworkability.

In the examples described below, a pull test and a reworkability test were conducted. These tests are tests for evaluating the ability to easily peel off the adhesive sheet in a bonded state without problems when peeling. The present invention provides a pressure-sensitive adhesive sheet having the performance (reworkability) that the substrate is not broken in such a test, and no residue of the pressure-sensitive adhesive is present. For example, when a component such as a battery pack of an information portable terminal such as a smart phone or a cellular phone is taken out, it is necessary to pull one end of the pressure-sensitive adhesive sheet and peel it off by stretching it. At this time, it is preferable that the pressure sensitive adhesive sheet can be easily peeled off, and that no residue such as a pressure-sensitive adhesive remains on the peeling point (place). Here, if the flexibility and stretchability of the base material are high, by pulling one end of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer in the bonding surface is continuously and uniformly stretched over a wide range to lower the adhesive strength adequately. As a result, It is possible to peel off easily without remaining. However, if the tensile strength of the substrate is low, the substrate may be destroyed. On the other hand, in the present invention, since a polyurethane resin having specific physical properties is used, each of these problems is less likely to occur.

The glass transition temperature (Tg) of the polyurethane resin is preferably -30 ° C or higher, more preferably -30 ° C to -10 ° C. The use of a polyurethane resin having a relatively high Tg in this manner makes it possible to provide a pressure-sensitive adhesive sheet excellent in reworkability without breaking the base material even in the case of delamination by stretching even when a base material having high flexibility or stretchability is used.

The weight average molecular weight (Mw) of the polyurethane resin is preferably 100,000 to 300,000, and more preferably 100,000 to 200,000. The use of a polyurethane resin having a relatively high Mw in this manner makes it possible to obtain a pressure-sensitive adhesive sheet excellent in reworkability, even when a base material having high flexibility and stretchability is not deteriorated in strength so much that the base material is not broken even in peeling by stretching.

The polyurethane resin is usually a polymer of a polyol and a polyfunctional isocyanate and is a resin containing a soft segment composed of a polyol monomer unit and a hard segment composed of a polyfunctional isocyanate compound or a low molecular weight glycol monomer unit.

The polyol used for the polyurethane resin is a compound having two or more hydroxyl groups. The number of hydroxyl groups in the polyol is preferably 2 to 3, more preferably 2. As the polyol, for example, polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil polyols can be used. Two or more kinds of polyols may be used in combination.

The polyester polyol is obtained, for example, by an esterification reaction between a polyol component and an acid component. Specific examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, Propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. Specific examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimeric acid, Cyclohexanedicarboxylic acid, 4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'- Of acid anhydrides.

Examples of the polyether polyol include water, a low molecular polyol (e.g., propylene glycol, ethylene glycol, glycerin, trimethylol propane, pentaerythritol), a bisphenol (e.g., bisphenol A), or dihydroxybenzene For example, catechol, resorcin, hydroquinone) as an initiator and addition polymerization of alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide and the like. Specific examples thereof include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Specific examples of the polycaprolactone polyol include ring-opening polymers of cyclic ester monomers such as? -Caprolactone and? -Valerolactone.

Specific examples of the polycarbonate polyol include a polycarbonate polyol obtained by polycondensation reaction of the respective polyol components and phosgene; The respective polyol components are reacted with carbonic acid diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, A polycarbonate polyol obtained by ester exchange condensation; A copolymerized polycarbonate polyol obtained by using two or more of the above polyol components in combination; A polycarbonate polyol obtained by esterifying each polycarbonate polyol and a carboxyl group-containing compound; A polycarbonate polyol obtained by etherification of each polycarbonate polyol and a hydroxyl group-containing compound; A polycarbonate polyol obtained by transesterifying each polycarbonate polyol with an ester compound; A polycarbonate polyol obtained by transesterifying each polycarbonate polyol and a hydroxyl group-containing compound; A polyester-based polycarbonate polyol obtained by subjecting each polycarbonate polyol to a polycondensation reaction with a dicarboxylic acid compound; A copolymerized polyether polycarbonate polyol obtained by copolymerizing the respective polycarbonate polyols and an alkylene oxide; .

The castor oil-based polyol is obtained, for example, by reacting a castor oil fatty acid with each of the polyol components (for example, polypropylene glycol).

As the polyfunctional isocyanate compound used for the polyurethane resin, for example, a polyfunctional aliphatic isocyanate compound, a polyfunctional alicyclic isocyanate compound, and a polyfunctional aromatic isocyanate compound can be used. Trimethylolpropane duct bodies of these compounds, buret bodies reacted with water, and trimer having an isocyanurate ring can also be used. Two or more polyfunctional isocyanate compounds may be used in combination.

Specific examples of the polyfunctional aromatic diisocyanate compound include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane Diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate and xylylene diisocyanate.

The polyurethane resin is obtained by curing a composition containing the polyol and the polyfunctional isocyanate compound described above. Particularly, a low-crystalline linear polyester-based polyurethane resin is preferable, and a hexane diol copolyester-based polyurethane resin and a polytetramethylene glycol-based polyurethane resin are more preferable.

Examples of commercially available products of the polyurethane resin include Desmall (registered trademark) of Sumika Bayer Urethane, and Nipporan (registered trademark) of Nippon Polyurethane High School. Specifically, in accordance with JIS K 6253 "Rubber Hardness Standard", a low-crystallinity resin specimen having a thickness of 6 mm was prepared, and the specimen was melted at 100 ° C. for 30 minutes to obtain an environment of 23 ± 2 ° C. and a relative humidity of 50 ± 5% , And then measuring the time until the hardness of the resin becomes Shore A90. Specifically, a resin having a time of 72 hours or more until Shore A 90 becomes a low-crystalline resin can be said.

In the present invention, it is preferable to use a crosslinking agent from the viewpoint of improving the physical properties of the base polymer. As the crosslinking agent, for example, a crosslinking agent of a metal chelating type, a metal alkoxide type, an epoxy type, an isocyanate type, an aziridine type, a polyfunctional acrylate, a carbodiimide type, an oxazoline type or a melamine type can be used. Of these, isocyanate-based crosslinking agents are preferable.

Other components may be added to the resin composition for constituting the substrate. Specific examples of the filler include a catalyst, a resin component, a foaming agent, a tackifier, an inorganic filler, an organic filler, a metal powder, a pigment, a foil, a softener, a plasticizer, An antioxidant, an ultraviolet absorber, a light stabilizer, a surface lubricant, a leveling agent, a corrosion inhibitor, a heat stabilizer, a polymerization inhibitor, a lubricant and a solvent.

The thickness of the substrate is preferably 20 to 200 mu m, more preferably 50 to 150 mu m.

<Pressure-sensitive adhesive layer>

The pressure-sensitive adhesive layer is a layer comprising a pressure-sensitive adhesive composition, and is provided on one side or both sides of the substrate. The pressure-sensitive adhesive composition may be any composition including a pressure-sensitive adhesive which does not adversely affect the effect of the present invention, and is not particularly limited. For example, emulsion adhesives, solvent adhesives, oligomer adhesives, solid adhesives, and hot-melt adhesives can be used. The pressure-sensitive adhesive layer is preferably composed of a pressure-sensitive adhesive in particular.

Examples of the pressure sensitive adhesive include acrylic pressure sensitive adhesives, natural pressure sensitive adhesives (natural rubber pressure sensitive adhesives or synthetic rubber pressure sensitive adhesives), silicone pressure sensitive adhesives, polyester pressure sensitive adhesives, urethane pressure sensitive adhesives, polyamide pressure sensitive adhesives, epoxy pressure sensitive adhesives, Fluorine-based pressure-sensitive adhesives. Two or more kinds of pressure-sensitive adhesives may be used in combination. Among them, an acrylic pressure-sensitive adhesive is preferable. The acrylic pressure-sensitive adhesive is generally a composition comprising, as a main component, a compound obtained by curing an acrylic copolymer [(meth) acrylic acid ester copolymer, etc.) as a base polymer with a crosslinking agent. To the pressure-sensitive adhesive, for example, a tackifier, a plasticizer, a filler, and a colorant may be added.

The pressure-sensitive adhesive layer can be formed, for example, by applying a pressure-sensitive adhesive on a substrate and performing crosslinking reaction by heating or ultraviolet irradiation. Further, for example, a pressure-sensitive adhesive may be coated on a release paper or other film and subjected to crosslinking reaction by heating or ultraviolet irradiation to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer may be bonded to one side or both sides of the substrate. For application of the pressure-sensitive adhesive, for example, a coating apparatus such as a roll coater, a die coater, a lip coater and the like can be used. In the case of heating after coating, the solvent in the pressure-sensitive adhesive composition can be removed along with the crosslinking reaction by heating.

<Adhesive sheet>

The pressure-sensitive adhesive sheet of the present invention has the above-described substrate and a pressure-sensitive adhesive layer provided on one side or both sides of the substrate. Side pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layer is provided only on one side of the substrate, but a double-side pressure-sensitive adhesive tape provided on both sides is particularly preferable. The thickness of the pressure-sensitive adhesive sheet is preferably 30 to 400 m, more preferably 50 to 300 m.

It is a feature of the pressure-sensitive adhesive sheet of the present invention that there is no breakage of the sheet upon peeling by stretching. Specifically, it is preferable that there is no destruction of the substrate in the following pull test.

[Pull test]

A stainless steel plate and a polycarbonate plate were attached to one side of a pressure-sensitive adhesive sheet having a width of 10 mm and a length of 45 mm, and after 90 minutes, a 90 degree peel test conforming to JIS Z 0237 was carried out.

The pressure-sensitive adhesive sheet of the present invention is also one of characteristic points having excellent tensile strength and elongation. Specifically, in the following tensile test, it is preferable that the tensile strength is 20 N / mm ² or more and the elongation is 500% or more.

[Tensile test]

The tensile strength at break (N / mm ² ) and elongation (%) at break were determined by fixing a pressure-sensitive adhesive sheet having a width of 10 mm and a length of 100 mm on a tensile tester set at a chuck interval of 30 mm and pulling at a speed of 300 mm / ).

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. In the following description, &quot; part &quot; means &quot; part by mass &quot;.

&Lt; Preparation of acrylic pressure-sensitive adhesive composition &

A reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas introducing tube was charged with 70 parts of 2-ethylhexyl acrylate, 4.9 parts of n-butyl acrylate, 10 parts of acrylic acid, 0.1 parts of 4-hydroxybutyl acrylate , 100 parts of ethyl acetate, 0.1 part of n-dodecanethiol as a chain transfer agent, and 0.1 part of lauryl peroxide as a radical polymerization initiator. Nitrogen gas was sealed in the reaction apparatus, and polymerization reaction was carried out at 68 占 폚 for 3 hours and then at 78 占 폚 for 3 hours under a nitrogen gas stream while stirring.

Thereafter, the reaction mixture was cooled to room temperature and ethyl acetate was added. Thus, an acrylic copolymer having a solid concentration of 30%, a theoretical Tg of 62.3 캜, and a weight average molecular weight of 1,100,000 was obtained. Then, 0.07 part of an isocyanate-based crosslinking agent (Colonate (registered trademark) L manufactured by Nippon Polyurethane Industry Co., Ltd.) and an appropriate amount of an organic solvent were added to 100 parts of the acrylic copolymer, and the mixture was stirred with an agitator until uniform, A composition was obtained

&Lt; Preparation of polyurethane resin composition &gt;

A low-crystalline linear polyester-based polyurethane resin solution and an isocyanate-based cross-linking agent (trade name: Colonate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) were added and stirred until uniformly dispersed with a stirrer to obtain a polyurethane resin composition. The type and amount (amount) of the polyurethane resin and the amount (part) of the crosslinking agent are shown in Table 1.

&Lt; Examples 1 to 3 and Comparative Examples 1 and 2 &gt;

The polyurethane resin composition was coated on one side of a release paper having silicone release agents formed on both sides thereof and dried at 50 DEG C for 2 minutes at 100 DEG C for 2 minutes to remove the solvent to obtain a resin base material (thickness 70 mu m).

The above-mentioned acrylic pressure-sensitive adhesive composition was applied to a release paper subjected to double-sided silicone release treatment and dried to form a pressure-sensitive adhesive layer. Then, this pressure-sensitive adhesive layer was bonded to the substrate. Further, the pressure-sensitive adhesive layer was bonded to the opposite surface by the same method. Thereafter, the mixture was aged at 40 占 폚 for 3 days, and the curing reaction of the pressure-sensitive adhesive layer was completed to obtain a double-sided pressure-sensitive adhesive sheet having a thickness of about 100 占 퐉 (thickness of each pressure-sensitive adhesive layer: about 15 占 퐉).

The properties and performance of each of the pressure-sensitive adhesive sheets thus obtained were evaluated according to the following methods. The results are shown in Table 1.

[Softening point of polyurethane resin]

The softening point of the polyurethane resin was measured in accordance with JIS K 7196 &quot; Method for testing softening temperature by thermomechanical analysis of thermoplastic plastic film and sheet &quot;.

[Glass transition temperature (Tg) of polyurethane resin]

For the dynamic viscoelasticity measurement, a linear polyester type polyurethane resin having a thickness of 0.2 mm was sandwiched between parallel halves of a measurement part of a tester using a viscoelasticity tester, and the storage elastic modulus (G ') from -100 캜 to 200 캜 at a frequency of 1 Hz, ) And the loss elastic modulus (G &quot;) were measured. Further, the glass transition temperature (Tg) was determined from Tanδ.

[Weight average molecular weight (Mw) of polyurethane resin]

The molecular weight of the acrylic copolymer in terms of standard polystyrene was measured by the GPC method under the following measuring apparatus and conditions and the weight average molecular weight (Mw) was measured.

Device: LC-2000 series (manufactured by Nihon Bunko K.K.)

· Column: 2 Shodex KF-806M, 1 Shodex KF-802

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 mL / min

· Column temperature: 40 ° C

· Injection volume: 100 μL

Detector: Refractometer (RI)

Measurement sample: A solution of a linear polyester-based polyurethane resin dissolved in THF to prepare a solution of 0.5 wt% of a linear polyester-based polyurethane resin and removing the dust by filtration through a filter.

[Pull test]

A stainless steel plate and a polycarbonate plate were attached to one side of a pressure-sensitive adhesive sheet having a size of 10 mm in width and 45 mm in length and a polycarbonate plate was attached to the other side. After 24 hours, a 90 degree peel test conforming to JIS Z 0237 was carried out. did.

&Amp; cir &amp;: The substrate was not destroyed and no residue of the pressure-sensitive adhesive was observed.

"×": The description was destroyed.

[Thinning processability]

The double-sided pressure-sensitive adhesive sheet was subjected to heat treatment at 65 DEG C and 80% RH in an atmosphere of 65 DEG C and 80% RH while keeping the pressure-sensitive adhesive sheet in a size of 10 in width and 5 mm in width and 125 mm in length I left it. Then, each of the release papers was peeled off in a 180-degree direction for each release, and adhesion with the adjacent portion was visually confirmed, and the wrinkle-formability was evaluated based on the following criteria.

&Amp; cir &amp;: Almost no adhesion to the adjacent portion was observed, and peeling was possible without peeling the adjacent portion.

&Quot; x &quot;: Significant adhesion was observed in the adjacent portion, and adjacent portions were simultaneously peeled off.

[Re-workability]

The double-faced pressure-sensitive adhesive sheet was stuck to a stainless steel plate, and after 90 minutes, a 90 degree peel test was carried out.

&Amp; cir &amp;: The substrate was not destroyed and no residue of the pressure-sensitive adhesive was observed.

"×": The description was destroyed.

[Load-carrying capacity]

The double-sided pressure-sensitive adhesive sheet was cut into a size of 25 x 25 mm, and one of the release papers was peeled off. The double-sided pressure-sensitive adhesive sheet was bonded to a test hook plate, and then the other release paper was peeled off and bonded to the polycarbonate plate. Then, a load of 700 gf was applied to the hook and maintained at 85 DEG C for 60 minutes, and the load-carrying property was evaluated based on the following criteria.

"○": The hook did not fall for 60 minutes.

"×": The hook fell within 60 minutes.

[Impact resistance]

The double-sided pressure-sensitive adhesive sheet was cut into a frame having a width of 0.8 mm and a size of 50 mm × 45 mm. One of the release papers was peeled off and attached to a glass plate having a thickness of 2 mm. The other release paper was peeled off and bonded to a polycarbonate plate having a thickness of 3 mm. Then, the autoclave was pressurized at 23 DEG C and 0.5 MPa for 1 hour. Also, the weight of the whole was adjusted to 250 g using an SUS plate and kept at -20 캜 for 1 hour or more. Then, at a height of 1.5 m, the test plate was vertically passed through the pail and dropped onto a concrete floor, and the number of times the glass plate was peeled off was measured.

[Waterproof]

The double-sided pressure-sensitive adhesive sheet was cut into a frame having a width of 0.8 mm and a size of 40 mm × 50 mm. One of the release papers was peeled off and bonded to a glass plate having a thickness of 2 mm, and the other release paper was peeled off to bond a glass plate having a thickness of 2 mm. For this sample, a 2 kg roller was reciprocated one time. After that, it was submerged according to the test method of IPX7 of the waterproof standard IEC "International Electrical Standard Meeting" 60529: 2001 [Equivalent Specification: JIS C 0920: 2003 "Protection Class (IP Code) , And evaluated whether or not the waterproof property of the IPX7 standard was satisfied (&quot; IPX7 &quot; in Table 1 satisfies the standard).

[Tensile strength and elongation]

The tensile strength (N / mm ² ) and elongation (%) at break of the double-sided pressure-sensitive adhesive sheet were measured at a rate of 300 mm / min by fixing them on a tensile tester having a width of 10 mm and a length of 100 mm, .

The abbreviations in Table 1 represent the following compounds.

[UE1]: A low-crystalline, linear polyester-based urethane elastomer (Desmall (registered trademark) 406, manufactured by Sumika Bayer Urethane Co., Ltd.)

[UE2]: A low-crystalline, linear polyester-based urethane elastomer (Nipporan (registered trademark) 2304, manufactured by Nippon Polyurethane Industry Co., Ltd.)

[UE3]: A low-crystalline, linear polyester-based urethane elastomer (SANFRENE (registered trademark) IB-1700D, manufactured by Sanyo Chemical Industries, Ltd.)

[UE4]: A low-crystalline, linear polyester-based urethane elastomer (SANFRENE (registered trademark) LQ-390, manufactured by Sanyo Chemical Industries, Ltd.)

&Quot; CR &quot;: isocyanate crosslinking agent (trade name: Colonate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)

<Evaluation>

As is evident from the results shown in Table 1, the pressure-sensitive adhesive sheets of Examples 1 and 2 were excellent in properties. On the other hand, in the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2, the substrate was broken in the pull test, and the reworkability and / or the tensile strength were inferior.

Industrial availability

Since the adhesive tape of the present invention has excellent reworkability, part replacement work is facilitated. Therefore, the adhesive tape of the present invention can be used as a component of a portable information terminal device such as a smart phone, a mobile phone, an electronic notebook, a PHS, a tablet PC, a digital camera, a music player, a portable TV, a notebook computer, It is useful in adhesive or fixing applications. Among them, it is very useful as a pressure sensitive adhesive sheet for fixing a battery pack and a case of a device such as a smart phone or a mobile phone.

Claims (9)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on both sides of a substrate and capable of being peeled off by stretching is characterized in that the substrate is obtained by using as a base polymer a linear polyester-based polyurethane resin having a softening point of 60 ° C or less according to JIS K 7196 Adhesive sheet. delete The method according to claim 1,
The pressure-sensitive adhesive sheet according to claim 1,
[Pull test]
A stainless steel plate and a polycarbonate plate were attached to one side of a pressure-sensitive adhesive sheet having a width of 10 mm and a length of 45 mm, and after 90 minutes, a 90 degree peel test conforming to JIS Z 0237 was carried out. The method according to claim 1,
Wherein the substrate has a glass transition temperature (Tg) of -30 占 폚 or higher. The method according to claim 1,
Wherein the polyurethane resin has a weight average molecular weight of 100,000 to 300,000. The method of claim 1,
Wherein the pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive. The method according to claim 1,
Wherein the thickness of the substrate is 20 to 200 mu m and the thickness of the adhesive sheet is 30 to 400 mu m. The method according to claim 1,
Sensitive adhesive sheet having a tensile strength of 20 N / mm ² or more and a elongation of 500% or more.
[Tensile test]
The tensile strength at break (N / mm ² ) and elongation (%) were measured by fixing a pressure-sensitive adhesive sheet having a width of 10 mm and a length of 100 mm to a tensile tester set at a chuck interval of 30 mm and pulling at a speed of 300 mm / do. delete