JP2016216597A - Temperature-sensitive adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature-sensitive adhesive composition capable of suppressing generation of adhesive residues.SOLUTION: There is provided a temperature-sensitive adhesive composition containing a side chain crystalline polymer which crystallizes at a temperature less than the melting point and shows followability at a temperature of the melting point or more, a crosslinking agent and a foaming agent which initiates expansion or foaming at a temperature of higher than the melting point, where the side chain crystalline polymer consists of a copolymer obtained by polymerizing (meth)acrylate having a linear alkyl group having at least 16 or more carbon atoms and acrylic acid, content of the crosslinking agent is 2.5 to 5.5 pts.wt. based on 100 pts.wt. of the side chain crystalline polymer and content of the foaming agent is 25 to 55 pts.wt. based on 100 pts.wt. of the side chain crystalline polymer.SELECTED DRAWING: None

Description

  The present invention relates to a temperature-sensitive adhesive composition.

  A temperature-sensitive adhesive is an adhesive containing a side-chain crystalline polymer that crystallizes at a temperature below the melting point and exhibits fluidity at a temperature above the melting point, and is temporarily fixed by being processed into an adhesive tape or an adhesive sheet. Used as a material.

  By the way, when the temperature-sensitive adhesive is peeled from the adherend, a so-called adhesive residue (residue) may be generated in which the temperature-sensitive adhesive is torn off and remains on the adherend. When adhesive residue is generated, a cleaning step is required, resulting in a decrease in productivity and an increase in cost. Moreover, there is a possibility that the adherend may be damaged when the adherend is removed.

The present applicant has previously developed a pressure-sensitive adhesive sheet as described in Patent Document 1 as a pressure-sensitive adhesive sheet that hardly causes adhesive residue.
However, even when the pressure-sensitive adhesive sheet described in Patent Document 1 is used, adhesive residue may occur depending on the composition. This tendency was remarkable when the adherend was a semiconductor wafer.

JP 2011-236291 A

  The subject of this invention is providing the temperature sensitive adhesive composition which can suppress generation | occurrence | production of adhesive residue.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a solution means having the following constitution and have completed the present invention.
(1) a side chain crystalline polymer that crystallizes at a temperature lower than the melting point and exhibits fluidity at a temperature equal to or higher than the melting point, a crosslinking agent, and a foaming agent that starts expansion or foaming at a temperature higher than the melting point; The side-chain crystalline polymer comprises a copolymer obtained by polymerizing (meth) acrylate and acrylic acid having a linear alkyl group having at least 16 carbon atoms, and contains the crosslinking agent. The amount is 2.5 to 5.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the blowing agent is 25 to 55 parts with respect to 100 parts by weight of the side chain crystalline polymer. The thermosensitive adhesive composition which is a weight part.
(2) The content of the crosslinking agent is 2.5 to 3.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is the side chain crystalline polymer. The temperature-sensitive adhesive composition according to (1), which is 45 to 55 parts by weight with respect to 100 parts by weight.
(3) The content of the crosslinking agent is 4.5 to 5.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is the side chain crystalline polymer. The temperature-sensitive adhesive composition according to (1), which is 25 to 35 parts by weight with respect to 100 parts by weight.
(4) The temperature-sensitive adhesive composition according to any one of (1) to (3), wherein the crosslinking agent is a metal chelate compound.
(5) The foaming agent is a microballoon foaming agent comprising: a hollow polymer shell having an average particle size in the micro order; and a heat-expandable substance enclosed in the polymer shell. The temperature-sensitive adhesive composition according to any one of 1) to (4).
(6) The temperature-sensitive adhesive according to any one of (1) to (5), wherein the melting point is 30 ° C. or higher, and the foaming agent is at a temperature lower than a temperature at which expansion or foaming starts. Composition.
(7) The temperature-sensitive adhesive composition according to any one of (1) to (6), wherein the storage elastic modulus G ′ at 23 ° C. is 1.6 × 10 ^{7 to} 2.9 × 10 ⁷ Pa. object.
(8) The temperature-sensitive adhesive composition according to any one of (1) to (7), wherein the storage elastic modulus G ′ at 60 ° C. is 3.0 × 10 ^{5 to} 7.0 × 10 ⁵ Pa. object.
(9) The temperature-sensitive adhesive composition according to any one of (1) to (8), wherein the storage elastic modulus G ′ at 150 ° C. is 1.3 × 10 ^{5 to} 3.0 × 10 ⁵ Pa. object.
(10) The 180 ° peel strength with respect to the polyethylene terephthalate film at an ambient temperature of 23 ° C. after passing through a temperature lower than the melting point and less than the temperature at which the foaming agent expands or starts foaming is 0.1 to 0. The temperature-sensitive adhesive composition according to any one of (1) to (9), which is 5 N / 25 mm.
(11) The adherend adhered at a temperature lower than the melting point and less than the temperature at which the foaming agent starts to expand or foam is fixed at a temperature lower than the melting point, and the foaming agent expands or foams. The temperature-sensitive adhesive composition according to any one of (1) to (10), wherein the temperature-sensitive adhesive composition is removed at a starting temperature.
(12) The temperature-sensitive adhesive composition according to any one of (1) to (11), wherein the adherend is a semiconductor wafer.
(13) A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive composition according to any one of (1) to (12).
(14) A temperature-sensitive adhesive formed by laminating an adhesive layer comprising the temperature-sensitive adhesive composition according to any one of (1) to (12) on one side or both sides of a film-like substrate. tape.

  According to the present invention, there is an effect that generation of adhesive residue can be suppressed.

Hereinafter, a temperature-sensitive adhesive composition according to an embodiment of the present invention (hereinafter sometimes referred to as “adhesive composition”) will be described in detail.
The pressure-sensitive adhesive composition of the present embodiment contains a side chain crystalline polymer, a crosslinking agent, and a foaming agent.

  The side chain crystalline polymer is a polymer having a melting point. The melting point is a temperature at which a specific portion of the polymer that is initially aligned in an ordered arrangement becomes disordered by an equilibrium process, and is measured by a differential thermal scanning calorimeter (DSC) at 10 ° C./min. It means the value obtained in this way.

  The side-chain crystalline polymer is crystallized at a temperature lower than the melting point described above, and undergoes phase transition and exhibits fluidity at a temperature higher than the melting point. That is, the side chain crystalline polymer has temperature sensitivity that reversibly causes a crystalline state and a fluid state in response to a temperature change. Accordingly, if the temperature of the pressure-sensitive adhesive composition is a temperature equal to or higher than the melting point and the temperature is lower than the temperature at which the foaming agent expands or starts foaming, the side-chain crystalline polymer is flowed. Since it exhibits adhesive strength, it can be attached to an adherend. Moreover, when the side chain crystalline polymer is flowed, the pressure-sensitive adhesive composition follows the fine uneven shape present on the surface of the adherend. Then, when the pressure-sensitive adhesive composition in this state is cooled to a temperature lower than the melting point, the side chain crystalline polymer is crystallized so that a so-called anchor effect appears, and as a result, the adherend is fixed with a high fixing force. Is possible. Further, when the pressure-sensitive adhesive composition is heated to a temperature at which the foaming agent expands or begins to foam, the side chain crystalline polymer exhibits fluidity, thereby reducing the cohesive force of the pressure-sensitive adhesive composition and expanding the foaming agent. Since it foams, the fixing force mentioned above can be reduced sufficiently and the adherend can be easily removed from the pressure-sensitive adhesive composition. Therefore, the pressure-sensitive adhesive composition of the present embodiment fixes the adherend adhered at a temperature below the melting point described above and at a temperature below the temperature at which the foaming agent starts to expand or foam, at a temperature below the melting point, It can be used as an adhesive that is removed at a temperature at which the foaming agent begins to expand or foam.

  The pressure-sensitive adhesive composition of the present embodiment can be attached to an adherend when the side chain crystalline polymer exhibits fluidity, and the adherend is removed when the side chain crystalline polymer is crystallized. Contains side chain crystalline polymer in a fixable proportion. That is, the pressure-sensitive adhesive composition of the present embodiment contains a side chain crystalline polymer as a main component, and is substantially composed of a side chain crystalline polymer to which a crosslinking agent and a foaming agent are added.

  The melting point of the side-chain crystalline polymer is preferably 30 ° C. or higher, and is preferably a temperature lower than the temperature at which the foaming agent starts to expand or foam, more preferably 30 to 50 ° C., and 40 to 50 More preferably, it is ° C. Thereby, at room temperature (23 ° C.), the pressure-sensitive adhesive composition does not express adhesive force because the side-chain crystalline polymer is in a crystalline state, and therefore the handleability of the pressure-sensitive adhesive composition is improved. As a result, workability can be improved. The melting point described above can be adjusted by changing the composition of the side chain crystalline polymer.

  The side chain crystalline polymer of this embodiment consists of a copolymer obtained by polymerizing (meth) acrylate and acrylic acid having a linear alkyl group having at least 16 carbon atoms.

  In the (meth) acrylate having a straight chain alkyl group having 16 or more carbon atoms, the straight chain alkyl group having 16 or more carbon atoms functions as a side chain crystalline site in the side chain crystalline polymer. That is, the side-chain crystalline polymer is a comb-shaped polymer having a straight-chain alkyl group having 16 or more carbon atoms in the side chain, and is crystallized by aligning the side chain in an ordered arrangement by intermolecular force or the like. To do. Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include carbon such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having a linear alkyl group of several 16 to 22 may be mentioned, and these may be used alone or in combination of two or more. Of these (meth) acrylates exemplified, behenyl acrylate is preferred. In addition, (meth) acrylate shall mean an acrylate or a methacrylate.

  Moreover, the side chain crystalline polymer of the present embodiment can be further polymerized with, for example, (meth) acrylate having an alkyl group having 1 to 6 carbon atoms. Examples of the (meth) acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and the like. You may use a seed | species or 2 or more types in mixture. Of these (meth) acrylates exemplified, butyl acrylate is preferred. Accordingly, the side chain crystalline polymer exhibits high fluidity at a temperature equal to or higher than the melting point, and the foaming agent is easily expanded or foamed.

  Each monomer mentioned above is 30-100 weight part of (meth) acrylate which has a C16 or more linear alkyl group, for example, and 0-70 weight of (meth) acrylate which has a C1-C6 alkyl group. It is preferable to polymerize 1 part by weight and 1 part by weight of acrylic acid. A preferred composition of the side chain crystalline polymer is, for example, a copolymer obtained by polymerizing 35 to 55 parts by weight of behenyl acrylate, 40 to 60 parts by weight of butyl acrylate and 1 to 10 parts by weight of acrylic acid. Examples include coalescence.

  The polymerization method is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method and the like can be employed. When the solution polymerization method is employed, the above-described monomer may be mixed in a solvent and stirred at about 40 to 90 ° C. for about 2 to 10 hours.

  The weight average molecular weight of the side chain crystalline polymer is preferably 500,000 to 800,000, and more preferably 550,000 to 700,000. The weight average molecular weight is a value obtained by measuring the side chain crystalline polymer by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  On the other hand, the pressure-sensitive adhesive composition of this embodiment contains a crosslinking agent as described above. Therefore, the above-mentioned side chain crystalline polymer is crosslinked by the crosslinking agent. The crosslinking reaction can be performed by heating and drying the pressure-sensitive adhesive composition. As conditions for heat drying, the temperature is about 70 to 80 ° C., and the time is about 1 to 20 minutes.

  As a crosslinking agent, a metal chelate compound, an aziridine compound, an isocyanate compound, an epoxy compound etc. are mentioned, for example. Among these, a metal chelate compound is preferable. In other words, the side chain crystalline polymer is preferably crosslinked by a metal chelate compound.

  Examples of metal chelate compounds include acetylacetone coordination compounds of polyvalent metals, acetoacetate coordination compounds of polyvalent metals, and the like. Examples of the polyvalent metal include aluminum, nickel, chromium, iron, titanium, zinc, cobalt, manganese, and zirconium. As the metal chelate compound, an acetylacetone coordination compound or acetoacetate coordination compound of aluminum is preferable, and aluminum trisacetylacetonate is more preferable. In addition, only 1 type may be used for a metal chelate compound, and 2 or more types may be mixed and used for it.

  Moreover, the adhesive composition of this embodiment contains a foaming agent as above-mentioned. As the foaming agent, both general chemical foaming agents and physical foaming agents can be employed. Chemical foaming agents include pyrolytic and reactive organic foaming agents and inorganic foaming agents.

  Examples of the pyrolytic organic foaming agent include various azo compounds (such as azodicarbonamide), nitroso compounds (such as N, N′-dinitrosopentamethylenetetramine), and hydrazine derivatives [4,4′-oxybis ( Benzenesulfonyl hydrazide)], semicarbazide compounds (hydrazodicarbonamide, etc.), azide compounds, tetrazole compounds, etc., and reactive organic foaming agents include, for example, isocyanate compounds.

  Examples of the thermal decomposition type inorganic foaming agent include bicarbonate / carbonate (such as sodium bicarbonate), nitrite / hydride and the like. Examples of the reactive inorganic foaming agent include bicarbonate. A combination of sodium and acid, a combination of hydrogen peroxide and yeast, a combination of zinc powder and acid, and the like can be mentioned.

  Examples of the physical blowing agent include organic physical blowing agents such as aliphatic hydrocarbons such as butane, pentane and hexane, chlorohydrocarbons such as dichloroethane and dichloromethane, and fluorinated chlorohydrocarbons such as chlorofluorocarbons; air, Examples thereof include inorganic physical foaming agents such as carbon dioxide gas and nitrogen gas.

  As another foaming agent, a so-called microballoon foaming agent that is microencapsulated thermally expandable fine particles can be employed. The microballoon foaming agent is obtained by encapsulating a heat-expandable substance made of a solid, liquid, or gas inside a polymer shell made of a thermoplastic or thermosetting resin. In other words, the microballoon foaming agent includes a hollow polymer shell having an average particle size of micro order, and a heat-expandable substance enclosed in the polymer shell. The microballoon foaming agent expands in volume by 40 times or more by heating, and a foam in the form of closed cells is obtained. Therefore, the microballoon foaming agent has a characteristic that the expansion ratio is considerably larger than that of a normal foaming agent. A commercial item can be used for the above-mentioned microballoon foaming agent. Examples of commercially available microballoon foaming agents include “461DU20” and “551DU40” manufactured by EXPANCEL.

  The foaming agent of this embodiment starts expansion or foaming at a temperature higher than the melting point of the side chain crystalline polymer described above. The temperature at which the foaming agent starts to expand or foam is preferably 90 ° C. or higher.

  Although it does not specifically limit as an average particle diameter of a foaming agent, Usually, it is preferable that it is 5-50 micrometers, and it is more preferable that it is 5-20 micrometers. The average particle diameter is a value obtained by measurement with a particle size distribution measuring device.

  Here, as described above, the pressure-sensitive adhesive composition of the present embodiment uses acrylic acid as a monomer constituting the side chain crystalline polymer. In this embodiment, acrylic acid functions as a crosslinking component (crosslinking point) that reacts with the crosslinking agent. In this embodiment, content of the crosslinking agent mentioned above is 2.5-5.5 weight part with respect to 100 weight part of side chain crystalline polymers. Moreover, content of the foaming agent mentioned above is 25-55 weight part with respect to 100 weight part of side chain crystalline polymers. According to these configurations, the adherend can be firmly fixed, the adherend can be easily removed when the foaming agent expands or foams, and the adhesive residue remains when peeled off from the adherend. Generation | occurrence | production can be suppressed.

  The following combinations are preferable for the contents of the above-mentioned crosslinking agent and foaming agent. That is, the content of the crosslinking agent is 2.5 to 3.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is based on 100 parts by weight of the side chain crystalline polymer. It is preferably 45 to 55 parts by weight. Further, the content of the crosslinking agent is 4.5 to 5.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is based on 100 parts by weight of the side chain crystalline polymer. It is preferably 25 to 35 parts by weight. When these combinations are employed, the above-described effects tend to be improved.

The pressure-sensitive adhesive composition preferably has a storage elastic modulus G ′ at 23 ° C. of 1.6 × 10 ^{7 to} 2.9 × 10 ⁷ Pa, and is preferably 1.6 × 10 ^{7 to} 2.6 × 10 ⁷ Pa. It is more preferable that The pressure-sensitive adhesive composition preferably has a storage elastic modulus G ′ at 60 ° C. of 3.0 × 10 ^{5 to} 7.0 × 10 ⁵ Pa, and 3.5 × 10 ^{5 to} 4.0 × 10. More preferably, it is ⁵ Pa. The pressure-sensitive adhesive composition preferably has a storage elastic modulus G ′ at 150 ° C. of 1.3 × 10 ^{5 to} 3.0 × 10 ⁵ Pa, and 1.3 × 10 ^{5 to} 2.0 × 10 ⁵ Pa. It is more preferable that When the pressure-sensitive adhesive composition has such a storage elastic modulus G ′, the above-described effect tends to be improved. The storage elastic modulus G ′ at each temperature is a value obtained by measurement with a dynamic viscoelasticity measuring device.

  The pressure-sensitive adhesive composition has a melting point of 180 ° peel strength with respect to the polyethylene terephthalate film at an ambient temperature of 23 ° C. after passing through a temperature lower than the temperature at which the foaming agent expands or starts foaming. 0.5 N / 25 mm is preferable, and 0.3 to 0.5 N / 25 mm is more preferable. As a result, the adherend can be firmly fixed at room temperature (23 ° C.). The 180 ° peel strength described above is a value measured according to JIS Z0237.

  In addition to the plasticizer and foaming agent described above, various additives such as a tackifier, a plasticizer, an anti-aging agent, and an ultraviolet absorber can be added to the pressure-sensitive adhesive composition.

  As a usage form of the adhesive composition of this embodiment mentioned above, the sheet-like form of a base material is mentioned, for example. The sheet shape is not limited to a sheet shape, and is a concept including a sheet shape or a film shape as long as the effects of the present embodiment are not impaired. When using an adhesive composition as a temperature sensitive adhesive sheet, it is preferable that the thickness is 15-400 micrometers, and it is more preferable that it is 20-150 micrometers.

  Moreover, the adhesive composition of this embodiment can also be used with a tape-shaped form. When the pressure-sensitive adhesive composition is used as a temperature-sensitive pressure-sensitive adhesive tape, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present embodiment may be laminated on one side or both sides of a film-like substrate. The film shape is not limited to a film shape, and is a concept including a film shape or a sheet shape as long as the effects of the present embodiment are not impaired.

  Examples of the constituent material of the base material include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. Synthetic resins are mentioned.

  The substrate may be either a single layer or a multilayer, and the thickness is usually about 5 to 500 μm. The substrate can be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc. in order to improve the adhesion to the pressure-sensitive adhesive layer.

  In order to laminate the pressure-sensitive adhesive layer on one or both sides of the substrate, the pressure-sensitive adhesive composition may be applied to one or both sides of the substrate with a coater or the like and dried. Examples of the coater include a knife coater, a roll coater, a calendar coater, a comma coater, a gravure coater, and a rod coater.

  As thickness of an adhesive layer, it is preferable that it is 5-60 micrometers, it is more preferable that it is 10-60 micrometers, and it is further more preferable that it is 10-50 micrometers. The thickness of the adhesive layer on one side and the thickness of the adhesive layer on the other side may be the same or different.

  In the present embodiment, the pressure-sensitive adhesive layer on the other side is not particularly limited as long as the pressure-sensitive adhesive layer on one side is composed of the above-described pressure-sensitive adhesive composition. For example, when the pressure-sensitive adhesive layer on the other side is composed of a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition described above, the composition may be the same as or different from the composition of the pressure-sensitive adhesive layer on one side. Good.

  Moreover, the pressure-sensitive adhesive layer on the other surface can be constituted by a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, for example. The pressure-sensitive adhesive is a tacky polymer, and examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene / butadiene latex-based adhesives, and acrylic adhesives.

  A release film is preferably laminated on the surface of the above-described temperature-sensitive adhesive sheet and temperature-sensitive adhesive tape of the present embodiment. As a release film, for example, a film made of polyethylene terephthalate or the like and a release agent such as silicone applied to the surface of the film can be used.

  The pressure-sensitive adhesive composition of the present embodiment described above can firmly fix the adherend when processing the adherend, and can easily remove the adherend when removing the processed adherend. It can be suitably used as a temporary fixing material in a field where it is required that adhesive residue is difficult to remain. Specifically, it can be suitably used as a temporary fixing material in a semiconductor wafer polishing step. Therefore, in the pressure-sensitive adhesive composition of this embodiment, the adherend is preferably a semiconductor wafer.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples. In the following description, “part” means part by weight.

(Synthesis example)
45 parts of behenyl acrylate, 50 parts of butyl acrylate, 5 parts of acrylic acid, and “Perbutyl ND” manufactured by NOF Corporation as a polymerization initiator at a ratio of 0.5 part to 230 parts of ethyl acetate, 55 The monomers were polymerized by stirring at 4 ° C. for 4 hours. The weight average molecular weight and melting point of the obtained copolymer are as follows.
Weight average molecular weight: 630,000 Melting point: 44 ° C

(Comparative synthesis example)
The monomer was polymerized in the same manner as in Synthesis Example 1 except that 5 parts of 2-hydroxyethyl acrylate was used instead of 5 parts of acrylic acid. The weight average molecular weight and melting point of the obtained copolymer are as follows.
Weight average molecular weight: 660,000 Melting point: 44 ° C

  Table 1 shows the copolymers of Synthesis Examples and Comparative Synthesis Examples. In addition, the weight average molecular weight was obtained by measuring a copolymer by GPC and converting the obtained measured value into polystyrene. The melting point was obtained by measuring the copolymer with DSC at 10 ° C./min.

[Examples 1-4 and Comparative Examples 1-3]
<Preparation of temperature-sensitive adhesive sheet>
First, each copolymer obtained in the synthesis example and the comparative synthesis example, that is, the side chain crystalline polymer is used in the combination shown in Table 2, and the crosslinking agent and the foaming agent are added in the proportions shown in Table 2 for temperature sensitivity. An adhesive composition was obtained. In addition, the addition amount of the crosslinking agent and the foaming agent shown in Table 2 is a value with respect to 100 parts of the side chain crystalline polymer in terms of solid content.

The added crosslinking agent is as follows.
Crosslinking agents of Examples 1 to 4 and Comparative Example 1: Metal chelate compound “aluminum chelate A (W)” manufactured by Kawaken Fine Chemical Co., Ltd.
Crosslinking agent of Comparative Examples 2-3: Isocyanate compound “Coronate L-45E” manufactured by Nippon Polyurethane Industry Co., Ltd.

The added foaming agent is as follows.
Foaming agent: Microballoon foaming agent “551DU40” manufactured by EXPANCEL having an average particle diameter of 10 to 16 μm and a foaming start temperature of 90 ° C. or higher.

  Next, the obtained temperature-sensitive adhesive composition was applied on a release film and heated at 80 ° C. for 10 minutes to cause a crosslinking reaction, thereby obtaining a 40 μm-thick temperature-sensitive adhesive sheet. As the release film, a polyethylene terephthalate film having a thickness of 50 μm obtained by applying silicone was used.

<Evaluation>
About the obtained temperature sensitive adhesive sheet, each storage elastic modulus G 'in 23 degreeC, 60 degreeC, and 150 degreeC, 180 degree peeling strength in 23 degreeC, foaming peelability, and adhesive residue property were evaluated. Each evaluation method is shown below, and the results are shown in Table 2.

(Storage modulus G ')
Each storage elastic modulus G ′ at 23 ° C., 60 ° C. and 150 ° C. is 1 Hz, 5 ° C./min, 0 using a dynamic viscoelasticity measuring device “HAAKE MARSIII” manufactured by Thermo Scientific. Measured during a temperature rising process of ˜200 ° C.

(180 ° peel strength at 23 ° C)
The 180 ° peel strength for a polyethylene terephthalate film at an ambient temperature of 23 ° C. was measured according to JIS Z0237. Specifically, first, a polyethylene terephthalate film having a thickness of 25 μm on one side of a thermosensitive pressure-sensitive adhesive sheet at an atmospheric temperature of 60 ° C., which is equal to or higher than the melting point and lower than the temperature at which the foaming agent starts to expand or foam. The other side was stuck on a glass pedestal. Next, after standing at an ambient temperature of 60 ° C. for 20 minutes, the ambient temperature was lowered to 23 ° C., left at this ambient temperature for 20 minutes, and then peeled 180 ° at a rate of 300 mm / min using a load cell, 180 ° peel strength between the temperature-sensitive adhesive sheet and the polyethylene terephthalate film was measured.

(Foaming peelability)
First, a thermosensitive adhesive sheet was attached to a circular glass plate having a diameter of 50 mm and a thickness of 500 μm at an atmospheric temperature of 60 ° C. Next, after standing at this ambient temperature for 20 minutes, the ambient temperature was lowered from 60 ° C. to 23 ° C., and after standing at this ambient temperature for 20 minutes, the ambient temperature was increased from 23 ° C. to 90 ° C. Then, the time for the glass plate to peel from the temperature-sensitive adhesive sheet with only its own weight was measured. The evaluation criteria were set as follows.
(Double-circle): A glass plate peels from a thermosensitive adhesive sheet only by its own weight within 1 minute after 90 degreeC temperature rising.
○: The glass plate peels off from the temperature-sensitive adhesive sheet only by its own weight within 3 minutes after the temperature rise at 90 ° C.
(Triangle | delta): A glass plate peels from a thermosensitive adhesive sheet only by dead weight within 10 minutes after 90 degreeC temperature rising.
X: Even if it exceeds 10 minutes after 90 degreeC temperature rise, a glass plate does not peel from a temperature-sensitive adhesive sheet only by its own weight.

(Adhesive residue)
In the above-described evaluation of foaming peelability, the surface of the glass plate after peeling was observed with an electron microscope (magnification: 100 times) to evaluate the adhesive residue. The evaluation criteria were set as follows.
A: There is no adhesive residue.
○: There is a slight adhesive residue within a range where there is no problem in actual use.
X: There is adhesive residue as a whole.

  As can be seen from Table 2, Examples 1 to 4 show good results in any of 180 ° peel strength at 23 ° C., foam peelability and adhesive residue. Especially Example 2-3 showed the result excellent in foaming peelability and adhesive residue. In addition, since the comparative example 1 was not able to stick to a glass plate, it was not able to evaluate foaming peelability and adhesive residue property.

Claims (14)

A side chain crystalline polymer that crystallizes at a temperature below the melting point and exhibits fluidity at a temperature above the melting point;
A crosslinking agent;
A foaming agent that starts expansion or foaming at a temperature higher than the melting point, and
The side chain crystalline polymer comprises a copolymer obtained by polymerizing (meth) acrylate and acrylic acid having a linear alkyl group having at least 16 carbon atoms,
The content of the crosslinking agent is 2.5 to 5.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer,
The temperature sensitive adhesive composition whose content of the said foaming agent is 25-55 weight part with respect to 100 weight part of said side chain crystalline polymers.   The content of the crosslinking agent is 2.5 to 3.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is 100 parts by weight of the side chain crystalline polymer. The temperature-sensitive adhesive composition according to claim 1, wherein the temperature-sensitive adhesive composition is 45 to 55 parts by weight.   The content of the crosslinking agent is 4.5 to 5.5 parts by weight with respect to 100 parts by weight of the side chain crystalline polymer, and the content of the foaming agent is 100 parts by weight of the side chain crystalline polymer. The temperature-sensitive adhesive composition according to claim 1, wherein the amount is 25 to 35 parts by weight.   The temperature-sensitive adhesive composition according to any one of claims 1 to 3, wherein the crosslinking agent is a metal chelate compound.   The said foaming agent is a microballoon foaming agent provided with the hollow polymer shell which has an average particle diameter of micro order, and the heat-expandable substance enclosed with the inside of the said polymer shell. The temperature-sensitive adhesive composition according to any one of the above.   The temperature-sensitive adhesive composition according to any one of claims 1 to 5, wherein the melting point is 30 ° C or higher, and the temperature is lower than a temperature at which the foaming agent starts to expand or foam. The temperature-sensitive adhesive composition according to claim 1, wherein the storage elastic modulus G ′ at 23 ° C. is 1.6 × 10 ^{7 to} 2.9 × 10 ⁷ Pa. The temperature-sensitive adhesive composition according to claim 1, wherein the storage elastic modulus G ′ at 60 ° C. is 3.0 × 10 ^{5 to} 7.0 × 10 ⁵ Pa. The temperature-sensitive adhesive composition according to any one of claims 1 to 8, wherein a storage elastic modulus G 'at 150 ° C is 1.3 x 10 ^{5 to} 3.0 x 10 ⁵ Pa.   180 ° peel strength with respect to the polyethylene terephthalate film at an ambient temperature of 23 ° C. after the temperature is equal to or higher than the melting point and less than the temperature at which the foaming agent starts expansion or foaming is 0.1 to 0.5 N / 25 mm. The temperature-sensitive adhesive composition according to any one of claims 1 to 9.   The temperature at which the foaming agent is fixed at a temperature lower than the melting point, and the foaming agent starts to expand or foam. The temperature-sensitive adhesive composition according to any one of claims 1 to 10, which is removed at a step.   The temperature-sensitive adhesive composition according to any one of claims 1 to 11, wherein the adherend is a semiconductor wafer.   A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive composition according to claim 1.   A temperature-sensitive pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising the temperature-sensitive pressure-sensitive adhesive composition according to claim 1, which is laminated on one side or both sides of a film-like substrate.