JP2019143065A - Temperature sensitive adhesive, temperature sensitive adhesive sheet and temperature sensitive adhesive tape - Google Patents

Abstract

To provide a temperature sensitive adhesive capable of firmly bonding to a polyimide-based adherend under room temperature and exfoliating easily since the adhesive force is decreased at a temperature higher than the melting point of a temperature sensitive resin.SOLUTION: There is provided a temperature sensitive adhesive which comprises a base resin (A) and a side chain crystalline polymer containing no carboxyl group (B), wherein the base resin (A) is a copolymer of a monomer mixture containing a carboxyl group-containing ethylenically unsaturated monomer (A1) and a (meth)acrylic ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms, the side chain crystalline polymer containing no carboxyl group (B) is a polymer containing a monomer component containing a (meth)acrylic ester (B1) having a linear alkyl group having 14 to 30 carbon atoms and the adhesive force to the polyimide-based adherend is decreased at a temperature higher than the melting point of the side chain crystalline polymer containing no carboxyl group (B).SELECTED DRAWING: None

Description

  The present invention relates to a thermosensitive adhesive, a thermosensitive adhesive sheet, and a thermosensitive adhesive tape.

  There is known a thermosensitive resin having a thermosensitive property that reversibly shows a crystalline state and a fluid state corresponding to a temperature change. For example, Patent Document 1 discloses a temperature-sensitive adhesive containing such a resin. The temperature-sensitive adhesive is a warm-off type that exhibits fixing strength at temperatures below the melting point of the temperature-sensitive resin, and can be peeled off with a marked decrease in adhesive strength at temperatures above the melting point of the temperature-sensitive resin. There is an adhesive.

  Conventional warm-off type adhesives include inorganic adherends such as stainless steel plates and glass, polyamide adherends, polyoxymethylene adherends, polyethylene terephthalate adherends, polymethyl methacrylate adherends. Adhesive strength is remarkably reduced at a temperature equal to or higher than the melting point of the temperature-sensitive resin, and can be easily peeled off from organic adherends such as bodies and polycarbonate adherends. However, among organic adherends, the adhesive strength does not decrease for polyimide adherends even at temperatures higher than the melting point of the temperature sensitive resin. As a result, when a conventional warm-off type adhesive is used for the polyimide-based adherend, it is difficult to remove the adhesive.

Japanese Patent Publication No. 6-510548

  An object of the present invention is to provide a temperature-sensitive adhesive that can be firmly peeled off at room temperature and has a low adhesive strength at a temperature equal to or higher than the melting point of the temperature-sensitive resin and can be easily peeled off. And a temperature-sensitive adhesive sheet and a temperature-sensitive adhesive tape containing such a temperature-sensitive adhesive.

As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following configuration, and have completed the present invention.
(1) It contains a base resin (A) and a carboxyl group-free side chain crystalline polymer (B), and the base resin (A) contains a carboxyl group-containing ethylenically unsaturated monomer (A1) and 4 to 7 carbon atoms. Is a copolymer of a monomer mixture containing a (meth) acrylic acid ester (A2) having a hydrocarbon group, and the carboxyl group-free side chain crystalline polymer (B) is a linear alkyl having 14 to 30 carbon atoms A polymer comprising a monomer component containing a (meth) acrylic acid ester (B1) having a group as a constituent unit, and a polyimide-based adherend at a temperature equal to or higher than the melting point of the carboxyl group-free side chain crystalline polymer (B) A temperature-sensitive adhesive with reduced adhesive strength.
(2) The monomer component of the carboxyl group-free side chain crystalline polymer (B) contains (meth) acrylic acid ester (B1) in a proportion of 30 to 70% by mass and has an alkyl group having 1 to 6 carbon atoms. The temperature-sensitive adhesive according to (1), further comprising (meth) acrylic acid ester (B2) at a ratio of 30 to 70% by mass.
(3) The temperature-sensitive adhesive according to (1) or (2), wherein the carboxyl group-free side chain crystalline polymer (B) has a weight average molecular weight of 3000 to 30000.
(4) The temperature-sensitive adhesive according to any one of (1) to (3), further including a crosslinking agent.
(5) The polyimide-based adherend has an adhesive strength of 2 N / 25 mm or more at 23 ° C. and an adhesive strength of 0.05 N / 25 mm or less at a temperature equal to or higher than the melting point of the side chain crystalline polymer ( The temperature-sensitive adhesive according to any one of 1) to (4).
(6) A temperature-sensitive adhesive sheet containing the temperature-sensitive adhesive according to any one of (1) to (5) above.
(7) A temperature-sensitive adhesive tape in which an adhesive layer containing the temperature-sensitive adhesive according to any one of (1) to (5) is formed on at least one surface of a substrate.

  According to the present invention, it is possible to firmly adhere to a polyimide-based adherend at room temperature, and the adhesive force is reduced at a temperature equal to or higher than the melting point of the temperature-sensitive resin, so that it can be easily peeled off. That is, at a temperature lower than the melting point of the thermosensitive resin such as at room temperature, strong adhesiveness is exhibited by the adhesiveness of the base resin (A) and the cohesive force of the carboxyl group-free side chain crystalline polymer (B). The On the other hand, at a temperature equal to or higher than the melting point of the thermosensitive resin, the surface free energy changes due to a change in the contact angle between the polyimide adherend and the thermosensitive resin. Therefore, the interfacial interaction between the polyimide adherend and the temperature-sensitive resin is reduced, the releasability is improved, and stress is easily concentrated on the molten temperature-sensitive resin dispersed on the base resin surface. Interfacial debonding.

  A temperature-sensitive adhesive according to an embodiment of the present disclosure will be described in detail. The temperature-sensitive adhesive according to one embodiment contains a base resin (A) and a carboxyl group-free side chain crystalline polymer (B), and the carboxyl group-free side chain crystalline polymer (B) (temperature sensitive). Adhesive strength decreases at a temperature equal to or higher than the melting point of the resin. In the present specification, “(meth) acryl” means “acryl” or “methacryl”.

  The base resin (A) is a copolymer of a monomer mixture containing a carboxyl group-containing ethylenically unsaturated monomer (A1) and a (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms. By using such a specific copolymer as the base resin (A), adhesiveness and peelability are exhibited specifically for the polyimide-based adherend.

  Examples of the carboxyl group-containing ethylenically unsaturated monomer (A1) include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and carboxyl group-containing unsaturated esters.

  Examples of the unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid. Examples of the unsaturated dicarboxylic acid include itaconic acid, maleic acid, and fumaric acid. Examples of the carboxyl group-containing unsaturated ester include β-carboxyethyl acrylate. As the carboxyl group-containing ethylenically unsaturated monomer (A1), only one type may be used, or two or more types may be used in combination. Among the carboxyl group-containing ethylenically unsaturated monomers (A1), acrylic acid, methacrylic acid, and acrylic acid are improved in that the adhesion to the polyimide-based adherend is improved and the peeling becomes easier when peeling. β-carboxyethyl is preferred. The carboxyl group-containing ethylenically unsaturated monomer (A1) is preferably contained in the monomer mixture in a proportion of 0.1 to 30% by mass, more preferably 1 to 20% by mass.

  The (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms is not particularly limited. For example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid tert-Butyl, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, tert-pentyl (meth) acrylate, n-hexyl (meth) acrylate, isohexyl (meth) acrylate, (meth) acrylic acid Examples include tert-hexyl, n-heptyl (meth) acrylate, isoheptyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Only 1 type may be used for the (meth) acrylic acid ester (A2) which has a C4-C7 hydrocarbon group, and 2 or more types may be used together. Among the (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms, the adhesiveness is further improved with respect to the polyimide-based adherend, and it becomes easier to peel when peeled. N-butyl acrylate, isobutyl acrylate, and tert-butyl acrylate are preferred. The (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms is preferably contained in the monomer mixture in a proportion of 70 to 99.9% by mass, more preferably 80 to 99% by mass. .

  The monomer mixture contains other monomers copolymerizable with the carboxyl group-containing ethylenically unsaturated monomer (A1) and the (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms. Also good. Examples of such other monomers include an ethylenically unsaturated monomer having a hydroxyl group, an ethylenically unsaturated monomer having an epoxy group, an ethylenically unsaturated monomer having an isocyanato group, and an alkyl group having 8 or more carbon atoms. (Meth) acrylic acid ester, (meth) acrylic acid ester having a cyclic hydrocarbon group having 8 or more carbon atoms, (meth) acrylic acid ester having an oxyethylene group, (meth) acrylic acid ester having an oxypropylene group, (Meth) acrylic acid ester having a fluorine atom in the molecule, (meth) acrylamide and the like can be mentioned.

  Examples of the ethylenically unsaturated monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 2 -Hydroxyhexyl, 2-hydroxyethyl acrylamide, etc. are mentioned. Examples of the ethylenically unsaturated monomer having an epoxy group include glycidyl (meth) acrylate. Examples of the ethylenically unsaturated monomer having an isocyanato group include 2-isocyanatoethyl (meth) acrylate. Examples of the (meth) acrylic acid ester having an oxyethylene group include methoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, and phenoxyethyl (meth) acrylate. Etc. Examples of the (meth) acrylic acid ester having an oxypropylene group include (meth) acrylic acid polypropylene glycol. Examples of the (meth) acrylic acid ester having a fluorine atom in the molecule include 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, Examples include (meth) acrylic acid 1H, 1H, 5H-octafluoropentyl. Examples of the (meth) acrylic acid ester having an alkyl group having 8 or more carbon atoms include ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, (meth ) Behenyl acrylate and the like. Examples of the (meth) acrylic acid ester having a cyclic hydrocarbon group having 8 or more carbon atoms include isobornyl (meth) acrylate.

  The polymerization method of the monomer mixture for obtaining the base resin (A) is not particularly limited, and examples thereof include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. For example, when employing a solution polymerization method, a monomer mixture and a solvent are mixed, a polymerization initiator and a chain transfer agent are added as necessary, and the reaction is carried out at about 50 to 100 ° C. for about 1 to 24 hours while stirring. You can do it.

  The weight average molecular weight (Mw) of such a base resin (A) is not particularly limited. The base resin (A) preferably has a weight average molecular weight of 100,000 to 2,000,000, more preferably 200,000 to 1,000,000.

  The carboxyl group-free side chain crystalline polymer (B) (hereinafter sometimes simply referred to as “side chain crystalline polymer (B)”) is a polymer having no carboxyl group in the molecule. The side-chain crystalline polymer (B) has a monomer component containing a (meth) acrylic acid ester (B1) having a linear alkyl group having 14 to 30 carbon atoms as a structural unit. Examples of the (meth) acrylic acid ester (B1) having a linear alkyl group having 14 to 30 carbon atoms include cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, (meth ) Behenyl acrylate, trimethosyl (meth) acrylate, and the like. Among such (meth) acrylic acid esters (A), (meth) acrylic acid esters having a linear alkyl group having 18 to 22 carbon atoms are preferred. As the (meth) acrylic acid ester (B1) having a linear alkyl group having 14 to 30 carbon atoms, only one type may be used, or two or more types may be used in combination.

  The monomer component which comprises the side chain crystalline polymer (B) will not be specifically limited if the (meth) acrylic acid ester (B1) is included. However, in order to prevent the side chain crystalline polymer (B) from having a carboxyl group in the molecule, the above-mentioned carboxyl group-containing ethylenically unsaturated monomer such as (meth) acrylic acid is a monomer component. Not adopted as. In addition to the (meth) acrylic acid ester (B1), the monomer component may include, for example, a (meth) acrylic acid ester (B2) having an alkyl group having 1 to 6 carbon atoms.

  Examples of the (meth) acrylic acid ester (B2) having an alkyl group having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Examples include isopropyl, butyl (meth) acrylate, and the like.

  In the monomer component constituting the side chain crystalline polymer (B), the (meth) acrylic acid ester (B1) having a linear alkyl group having 14 to 30 carbon atoms is preferably 30 to 70% by mass, More preferably, it is contained in a proportion of 40 to 60% by mass. The (meth) acrylic acid ester (B2) having a C 1-6 alkyl group is preferably contained in a proportion of 30 to 70% by mass, more preferably 40 to 60% by mass.

  The polymerization method of the monomer component for obtaining the side chain crystalline polymer (B) is not particularly limited, and examples thereof include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. For example, when the solution polymerization method is adopted, the monomer component and the solvent are mixed, a polymerization initiator and a chain transfer agent are added as necessary, and the reaction is performed at about 50 to 100 ° C. for about 1 to 6 hours while stirring. You can do it.

  The weight average molecular weight (Mw) of such a side chain crystalline polymer (B) is not particularly limited. The side chain crystalline polymer (B) preferably has a weight average molecular weight of 3000 to 30000, more preferably 6000 to 15000.

  The adhesive strength of the side chain crystalline polymer (B) decreases at a temperature equal to or higher than the melting point (Tm). That is, the side chain crystalline polymer (B) is crystallized at a temperature below the melting point, and undergoes phase transition at a temperature above the melting point to exhibit fluidity. The melting point of the side chain crystalline polymer is not particularly limited. The side chain crystalline polymer preferably has a melting point of 70 ° C. or lower, more preferably 60 ° C. or lower. As used herein, “melting point” refers to the temperature at which a particular portion of a polymer that was initially aligned in an ordered arrangement becomes disordered by an equilibrium process, and is measured by a differential thermal scanning calorimeter (DSC) of 10 It is obtained by measuring under the condition of ° C / min.

  The temperature-sensitive adhesive according to an embodiment of the present disclosure includes the base resin (A) and the side chain crystalline polymer (B) in an arbitrary ratio, and preferably 100 parts by mass of the base resin (A). The side chain crystalline polymer (B) is contained in an amount of 1 to 30 parts by mass, more preferably 3 to 20 parts by mass. The temperature-sensitive adhesive according to an embodiment of the present disclosure is obtained by mixing and stirring the base resin (A) and the side chain crystalline polymer (B).

  Furthermore, the temperature-sensitive adhesive according to an embodiment of the present disclosure may include a crosslinking agent in order to improve cohesion. The crosslinking agent is not particularly limited, and examples thereof include an aziridine compound, an epoxy compound, a metal chelate compound, a metal alkoxide compound, and an isocyanate compound. Of these, metal chelate compounds are preferred. By using a metal chelate compound, dissipation of peeling energy in a high temperature range is suppressed, and resistance during peeling is easily suppressed.

  The temperature-sensitive adhesive according to an embodiment of the present disclosure may include a plasticizer, a tackifier, a filler, an antioxidant, and the like as necessary. Examples of tackifiers include special rosin ester, terpene phenol, petroleum resin, high hydroxyl value rosin ester, and hydrogenated rosin ester. Furthermore, in order to further improve the adhesion to the polyimide-based adherend, a general pressure-sensitive adhesive such as acrylic or rubber may be added.

  The temperature-sensitive adhesive according to an embodiment of the present disclosure preferably has an adhesive strength of 2 N / 25 mm or more at 23 ° C. with respect to the polyimide-based adherend, and the side chain crystalline polymer (B). It has an adhesive strength of 0.05 N / 25 mm or less at a temperature higher than the melting point. In this specification, the adhesive strength is measured at 300 mm / min according to JIS Z0237, and is a value for a polyimide-based adherend. When the temperature-sensitive adhesive has such a range of adhesive strength, the polyimide-based adherend is more firmly attached at room temperature (temperature lower than the melting point of the side chain crystalline polymer (B)). The pressure-sensitive adhesive can be more easily peeled from the polyimide adherend at a temperature equal to or higher than the melting point of the side chain crystalline polymer (B). More preferably, the thermosensitive adhesive has an adhesive strength of 5 N / 25 mm or more at 23 ° C. and an adhesive strength of 0.05 N / 25 mm or less at a temperature equal to or higher than the melting point of the side chain crystalline polymer (B). .

  When the temperature-sensitive adhesive is peeled off, it is often peeled off at a higher speed (for example, about 3000 mm / min) than the speed defined by JIS. Generally, when peeling at high speed, the peel strength tends to increase. However, when the peel strength at 300 mm / min specified by JIS is sufficiently low, such as 0.05 N / 25 mm or less, the peel strength is unlikely to increase even when peeled at a high speed. Therefore, the temperature-sensitive adhesive according to one embodiment can be peeled without damaging the polyimide-based adherend regardless of the peeling speed.

  The usage method of the temperature-sensitive adhesive according to an embodiment of the present disclosure is not particularly limited. For example, the temperature-sensitive adhesive may be applied to a target polyimide-based adherend and used. The adhesive may be formed into a sheet and used as a baseless tape.

  Or you may use the adhesive layer containing the temperature sensitive adhesive which concerns on one Embodiment of this indication with the form of the temperature sensitive adhesive tape formed in the at least one surface of the base material. The substrate is preferably in the form of a film, and the film form includes a sheet form. Examples of the constituent material of the substrate include polyethylene, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyester, polyamide, polyimide, polyamideimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer Synthetic resins such as coalescence, polyvinyl chloride, polyether ether ketone, and the like can be mentioned.

  The base material may have a single layer structure or a multilayer structure. The substrate usually has a thickness of about 5 to 500 μm. Furthermore, the substrate may be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc. for the purpose of improving the adhesion to the adhesive layer.

  The method for forming the pressure-sensitive adhesive layer containing the temperature-sensitive pressure-sensitive adhesive on at least one surface of the substrate is not particularly limited. For example, there may be mentioned a method in which a coating solution in which a solvent is added to a temperature-sensitive adhesive as required is applied to one or both sides of a 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. The thickness of the pressure-sensitive adhesive layer is not particularly limited. The pressure-sensitive adhesive layer preferably has a thickness of about 1 to 500 μm, more preferably about 5 to 60 μm.

  A temperature-sensitive adhesive tape in which a pressure-sensitive adhesive layer containing a temperature-sensitive adhesive is formed only on one surface of a substrate may have a pressure-sensitive adhesive layer formed on the other surface, for example. A layer containing a warm adhesive and a pressure sensitive adhesive may be formed. Examples of pressure-sensitive adhesives include natural rubber adhesives, synthetic rubber adhesives, styrene-butadiene latex-based adhesives, block copolymer type thermoplastic rubbers, butyl rubber, polyisobutylene, acrylic adhesives, and vinyl ether copolymers. Etc. Commercially available pressure-sensitive adhesives may be used.

  According to the temperature-sensitive adhesive according to an embodiment of the present disclosure, the adhesive strength is remarkably reduced at a temperature equal to or higher than the melting point of the temperature-sensitive resin and can be easily peeled from the polyimide-based adherend. . That is, adhesiveness and peelability are exhibited specifically for the polyimide-based adherend. Therefore, by using the temperature-sensitive adhesive according to one embodiment of the present disclosure, the polyimide-based adherend can be processed while being fixed at room temperature. After processing, the temperature-sensitive adhesive can be easily peeled off from the polyimide-based adherend by raising the temperature to a temperature equal to or higher than the melting point of the side chain crystalline polymer (B) contained in the temperature-sensitive adhesive. . The same applies to a temperature-sensitive adhesive sheet and a temperature-sensitive adhesive tape using the temperature-sensitive adhesive according to an embodiment of the present disclosure.

  The temperature-sensitive adhesive, the temperature-sensitive adhesive sheet, and the temperature-sensitive adhesive tape according to an embodiment of the present disclosure are, for example, a carrier tape, a masking tape, a fixing during dicing, and a fixing during a transfer process. used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these Examples.

(Synthesis Example A1: Synthesis of base resin)
As shown in Table 1, 92% by mass of n-butyl acrylate and 8% by mass of acrylic acid were mixed to obtain a monomer mixture. With respect to 100 parts by mass of this monomer mixture, 0.5 parts by mass of perbutyl ND (manufactured by NOF Corporation) as a polymerization initiator and 230 parts by mass of methyl acetate as a solvent are added at a rate of 4 Polymerized for hours. Thereafter, the temperature was raised to 80 ° C., and perhexyl PV (manufactured by NOF Corporation) was added as a polymerization initiator at a ratio of 0.5 part by mass with respect to 100 parts by mass of the monomer mixture. After addition, polymerization was performed for 2 hours to obtain a copolymer (base resin). The obtained base resin had a weight average molecular weight (Mw) of about 400,000.

(Synthesis Examples A2 to A6: Synthesis of base resin)
A copolymer (base resin) was obtained in the same procedure as in Synthesis Example A1, except that the monomer components listed in Table 1 were used in the proportions listed in Table 1. Table 1 shows the Mw of each base resin.

(Comparative Synthesis Examples A1 to A3: Synthesis of base resin)
A copolymer (base resin) was obtained in the same procedure as in Synthesis Example A1, except that the monomer components listed in Table 1 were used in the proportions listed in Table 1. Table 1 shows the Mw of each base resin.

(Synthesis Example B1: Synthesis of Side Chain Crystalline Polymer)
As shown in Table 2, 45% by mass of behenyl acrylate (manufactured by NOF Corporation) and 55% by mass of methyl acrylate were mixed to obtain a monomer mixture. For 100 parts by mass of the monomer mixture, 1 part by mass of perhexyl PV (manufactured by NOF Corporation) as a polymerization initiator, 6 parts by mass of dodecyl mercaptan (manufactured by Tokyo Chemical Industry Co., Ltd.), and toluene as a solvent. The copolymer was added at a ratio of 100 parts by mass and polymerized at 80 ° C. for 3 hours to obtain a copolymer (side chain crystalline polymer). The resulting side chain crystalline polymer had a weight average molecular weight (Mw) of about 8000 and a melting point (Tm) of about 50 ° C.

(Synthesis Examples B2 and B3: Synthesis of side chain crystalline polymer)
A copolymer (side chain crystalline polymer) was obtained in the same procedure as in Synthesis Example B1, except that the monomer components listed in Table 2 were used in the proportions listed in Table 2. Table 2 shows Mw and Tm of each side chain crystalline polymer.

(Comparative Synthesis Examples B1 and B2: Synthesis of Side Chain Crystalline Polymer)
A copolymer (side chain crystalline polymer) was obtained in the same procedure as in Synthesis Example B1, except that the monomer components listed in Table 2 were used in the proportions listed in Table 2. Table 2 shows Mw and Tm of each side chain crystalline polymer.

(Example 1)
With respect to 100 parts by mass of the base resin obtained in Synthesis Example A1, the side chain crystalline polymer obtained in Synthesis Example B1 was mixed at a ratio of 5 parts by mass to obtain a temperature-sensitive adhesive. The obtained temperature sensitive adhesive was dissolved in ethyl acetate so as to have a concentration of 30% by mass to prepare a temperature sensitive adhesive solution. To the obtained solution, a metal chelate crosslinking agent (aluminum trisacetylacetonate, manufactured by Kawaken Fine Chemical Co., Ltd.) was added as a crosslinking agent at a ratio of 1 part by mass with respect to 100 parts by mass of the base resin. A pressure-sensitive adhesive composition was obtained. The obtained temperature-sensitive adhesive composition was applied to one side of a substrate (PET film having a thickness of 100 μm) to form an adhesive layer. The pressure-sensitive adhesive layer had a thickness of 30 μm. Thus, a temperature sensitive adhesive tape was obtained.

The adhesive strength of the obtained temperature-sensitive adhesive tape was measured according to JIS Z0237. Specifically, a temperature-sensitive adhesive tape was punched into a 25 mm-wide strip and attached to an adherend formed of polyimide using a 2 kg roller. The sample was left stationary at 23 ° C. for 20 minutes and fixed, and the temperature-sensitive adhesive tape was peeled off 180 ° at a speed of 300 mm / min using a load cell, and the sample was peeled off without any residue at the adhesive / adherent interface. The adhesive strength at 0 ° C. was measured. The obtained adhesive strength was evaluated according to the following criteria, and in the case of A or B, it was evaluated that it had sufficient fixability. The results are shown in Table 3.
<Evaluation criteria>
A: When the adhesive strength is 5 N / 25 mm or more.
B: When the adhesive strength is 2 N / 25 mm or more and less than 5 N / 25 mm.
C: When the adhesive strength is less than 2 N / 25 mm.

Next, the same procedure as described above was performed until the sample was left to stand at 23 ° C. for 20 minutes and fixed. Then, it left still at 60 degreeC for 20 minute (s), the thermosensitive adhesive tape was peeled 180 degree | times at the speed | rate of 300 mm / min using the load cell, and the adhesive strength in 60 degreeC was measured. The obtained adhesive strength was evaluated according to the following criteria, and in the case of A or B, it was evaluated that it had sufficient peelability. The results are shown in Table 3.
<Evaluation criteria>
A: When the adhesive strength is 0.05 N / 25 mm or less.
B: When the adhesive strength exceeds 0.05 N / 25 mm and is 0.1 N / 25 mm or less.
C: When the adhesive strength exceeds 0.1 N / 25 mm.

(Examples 2 to 8)
A temperature-sensitive adhesive was obtained in the same procedure as in Example 1 except that the base resin and side chain crystalline polymer shown in Table 3 were used in the proportions shown in Table 3. A temperature-sensitive adhesive composition was obtained in the same procedure as in Example 1 except that each of the obtained temperature-sensitive adhesives was used. A temperature-sensitive adhesive tape was obtained in the same procedure as in Example 1 except that each of the obtained temperature-sensitive adhesive compositions was used. The pressure-sensitive adhesive layer of the temperature-sensitive pressure-sensitive adhesive tape had a thickness of 30 μm. For each of the temperature-sensitive adhesive tapes obtained in Examples 2 to 8, the adhesive strength at 23 ° C. and 60 ° C. was measured in the same procedure as in Example 1. The results are shown in Table 3.

(Comparative Examples 1-6)
A temperature-sensitive adhesive was obtained in the same procedure as in Example 1 except that the base resin and side chain crystalline polymer shown in Table 3 were used in the proportions shown in Table 3. Each of the obtained temperature-sensitive adhesives was dissolved in ethyl acetate to a concentration of 30% by mass, and a metal chelate crosslinking agent (aluminum trisacetylacetonate, manufactured by Kawaken Fine Chemical Co., Ltd.) was used as the base resin. In Comparative Examples 1-3, 1 part by mass was added to 100 parts by mass, and in Comparative Examples 4-6, 2 parts by mass was added to obtain a temperature-sensitive adhesive composition. A temperature-sensitive adhesive tape was obtained in the same procedure as in Example 1 except that each of the obtained temperature-sensitive adhesive compositions was used. The pressure-sensitive adhesive layer of the temperature-sensitive pressure-sensitive adhesive tape had a thickness of 30 μm. For each of the temperature-sensitive adhesive tapes obtained in Comparative Examples 1 to 6, the adhesive strength at 23 ° C. and 60 ° C. was measured in the same procedure as in Example 1. The results are shown in Table 3.

(Comparative Examples 7 and 8)
A temperature-sensitive adhesive was obtained in the same procedure as in Example 1 except that the base resin and side chain crystalline polymer shown in Table 3 were used in the proportions shown in Table 3. Each of the obtained temperature-sensitive adhesives was dissolved in ethyl acetate so as to have a concentration of 30% by mass, and an isocyanate crosslinking agent (Coronate L45, manufactured by Tosoh Corporation) was added to 100 parts by mass of the base resin. Was added at a ratio of 1 part by mass to obtain a temperature-sensitive adhesive composition. A temperature-sensitive adhesive tape was obtained in the same procedure as in Example 1 except that each of the obtained temperature-sensitive adhesive compositions was used. The pressure-sensitive adhesive layer of the temperature-sensitive pressure-sensitive adhesive tape had a thickness of 30 μm. For each of the temperature-sensitive adhesive tapes obtained in Comparative Examples 1 to 8, the adhesive strength at 23 ° C. and 60 ° C. was measured in the same procedure as in Example 1. The results are shown in Table 3.

  As shown in Table 3, the temperature-sensitive adhesives (temperature-sensitive adhesive tapes) obtained in Examples 1 to 8 are sufficient at 23 ° C. (room temperature) for adherends formed of polyimide. It can be seen that it has fixing properties and has sufficient peelability at 60 ° C. (temperature higher than the melting point of the side chain crystalline polymer). Therefore, the temperature-sensitive adhesive (temperature-sensitive adhesive tape) obtained in Examples 1 to 8 can sufficiently fix the polyimide-based adherend at room temperature and has a melting point higher than that of the side chain crystalline polymer. At this temperature, it can be easily peeled off from the polyimide adherend.

  On the other hand, in Comparative Example 1, no side chain crystalline polymer was used, and in Comparative Examples 2, 3, 6 and 8, a side chain crystalline polymer containing a carboxyl group in the molecule was used, and Comparative Examples 4 to 8 were used. Then, the copolymer of the monomer mixture which does not contain the (meth) acrylic acid ester (A2) which has a C4-C7 hydrocarbon group is used as base resin. Therefore, it turns out that the temperature-sensitive adhesive (temperature-sensitive adhesive tape) obtained in Comparative Examples 1 to 8 is inferior to at least one of fixability and peelability with respect to the adherend formed of polyimide. .

Claims (7)

Containing a base resin (A) and a carboxyl group-free side chain crystalline polymer (B),
The base resin (A) is a copolymer of a monomer mixture containing a carboxyl group-containing ethylenically unsaturated monomer (A1) and a (meth) acrylic acid ester (A2) having a hydrocarbon group having 4 to 7 carbon atoms,
The carboxyl group-free side chain crystalline polymer (B) is a polymer having a monomer component containing a (meth) acrylic acid ester (B1) having a linear alkyl group having 14 to 30 carbon atoms as a structural unit,
A temperature-sensitive adhesive in which the adhesive strength to a polyimide-based adherend is reduced at a temperature equal to or higher than the melting point of the carboxyl group-free side chain crystalline polymer (B).   The monomer component of the carboxyl group-free side chain crystalline polymer (B) contains the (meth) acrylic acid ester (B1) in a proportion of 30 to 70% by mass and has an alkyl group having 1 to 6 carbon atoms ( The temperature-sensitive adhesive according to claim 1, further comprising (meth) acrylic acid ester (B2) at a ratio of 30 to 70% by mass.   The temperature-sensitive adhesive according to claim 1 or 2, wherein the carboxyl group-free side chain crystalline polymer (B) has a weight average molecular weight of 3000 to 30000.   The temperature-sensitive adhesive according to any one of claims 1 to 3, further comprising a crosslinking agent.   2. The polyimide-based adherend has an adhesive strength of 2 N / 25 mm or more at 23 ° C. and an adhesive strength of 0.05 N / 25 mm or less at a temperature equal to or higher than the melting point of the side chain crystalline polymer. The temperature sensitive adhesive in any one of -4.   A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive according to claim 1.   The temperature-sensitive adhesive tape in which the adhesive layer containing the temperature-sensitive adhesive in any one of Claims 1-5 was formed in the at least one surface of the base material.