WO2023021773A1

WO2023021773A1 - Pressure-sensitive adhesive sheet

Info

Publication number: WO2023021773A1
Application number: PCT/JP2022/013629
Authority: WO
Inventors: 高正平山; 昭徳西尾
Original assignee: 日東電工株式会社
Priority date: 2021-08-19
Filing date: 2022-03-23
Publication date: 2023-02-23
Also published as: TW202308842A; KR20240011775A; CN117858930A; JPWO2023021773A1

Abstract

Provided is a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer which can be formed with low heat energy and can exhibit excellent adhesive force.　This pressure-sensitive adhesive sheet comprises a substrate and a pressure-sensitive adhesive layer disposed on at least one side of the substrate, wherein the pressure-sensitive adhesive layer comprises: a (meth)acrylic polymer as a base polymer; an isocyanate-based crosslinking agent and/or an epoxy-based crosslinking agent, as a crosslinking agent; an amino compound having a tertiary-amino group and capable of multidentate coordination and/or an organic tin(IV) compound capable of multidentate coordination, as a low-molecular-weight compound; and fine heat-expandable spheres. The (meth)acrylic polymer includes a constituent unit having an active-hydrogen group.

Description

Adhesive sheet

The present invention relates to an adhesive sheet. More particularly, it relates to a pressure-sensitive adhesive sheet that can exhibit easy peelability in response to thermal stimulation.

Conventionally, when processing electronic components, etc., adhesive sheets are sometimes used to fix or temporarily fix the workpiece. For example, an adhesive sheet is used as a temporary fixing material for cutting semiconductor wafers or ceramic sheets, or as a temporary fixing material in the process of sealing a semiconductor chip with resin (chip size package: CSP or wafer level package: WLP). An adhesive sheet may be used. As one of such adhesive sheets, a pressure-sensitive adhesive sheet that has an adhesive layer containing heat-expandable microspheres and whose adhesive strength is reduced by expansion of the heat-expandable microspheres by heating has been studied.

The above adhesive sheet usually comprises an adhesive layer formed by coating (applying and drying) an adhesive containing a base polymer and a solvent. Conventionally, aromatic hydrocarbon solvents such as toluene and dichlorobenzene are often used as the solvent. An aromatic hydrocarbon solvent has excellent solubility and a high boiling point, and is therefore advantageous in that a pressure-sensitive adhesive having excellent storage stability can be obtained by using it.

On the other hand, in recent years, efforts have been made to reduce the use of aromatic hydrocarbon solvents, which have a high boiling point, because they require a large amount of energy to volatilize during the formation of the adhesive layer, and from the viewpoint of toxicity. For example, the above problem can be solved by using a solvent containing non-aromatic hydrocarbons (non-aromatic hydrocarbon solvents) having a boiling point of less than 100° C., such as acetone, methyl ethyl ketone, and ethyl acetate.

Japanese Patent Application Laid-Open No. 2003-201452

However, if an adhesive containing a non-aromatic hydrocarbon solvent with a boiling point of less than 100°C is used to form an adhesive layer, an adhesive layer that does not exhibit sufficient adhesive strength may be formed. Even if it contains a base polymer that can achieve sufficient adhesive strength when combined with an aromatic hydrocarbon solvent, it contains the above non-aromatic hydrocarbon solvent instead of the aromatic hydrocarbon solvent. , a PSA sheet that does not have sufficient adhesive strength may be obtained.

The present invention has been made to solve the above-mentioned conventional problems, and the object thereof is to provide a pressure-sensitive adhesive layer that consumes less heat energy when forming the pressure-sensitive adhesive layer and that can exhibit excellent adhesive strength. To provide a pressure-sensitive adhesive sheet comprising

The pressure-sensitive adhesive sheet of the present invention comprises a base material and a pressure-sensitive adhesive layer disposed on at least one side of the base material, the pressure-sensitive adhesive layer comprising a (meth)acrylic polymer as a base polymer and a cross-linking agent. an isocyanate-based cross-linking agent and/or an epoxy-based cross-linking agent, and an amino compound having a tertiary amino group capable of multidentate coordination as a low-molecular-weight compound and/or an organic tin (IV) compound capable of multidentate coordination , and heat-expandable microspheres, and the (meth)acrylic polymer contains a structural unit having an active hydrogen group.
In one embodiment, the content of the amino compound having a tertiary amino group capable of multidentate coordination and the organotin (IV) compound capable of multidentate coordination is relative to 100 parts by weight of the base polymer. , 0.001 to 10 parts by weight.
In one embodiment, the amino compound having a tertiary amino group capable of multidentate coordination is an amino compound containing at least two tertiary amino groups in the molecule.
In one embodiment, the amino compound having a tertiary amino group capable of multidentate coordination is 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0 ]undec-7-ene and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.
In one embodiment, the organotin(IV) compounds capable of multidentate coordination are dialkyltin(IV) fatty acid esters.
In one embodiment, the organotin(IV) compound capable of multidentate coordination consists of dibutyltin(IV) dilaurate, dibutyltin(IV) dioctate, dioctyltin(IV) dilaurate and dibutyltin(IV) diacetate. At least one selected from the group.
In one embodiment, the active hydrogen group is a hydroxyl group and/or a carboxyl group.
In one embodiment, the thermally expandable microspheres have an expansion temperature of 80°C to 250°C.
In one embodiment, another pressure-sensitive adhesive layer is further provided on the opposite side of the base material to the pressure-sensitive adhesive layer.
According to another aspect of the present invention, there is provided a method for producing the pressure-sensitive adhesive sheet. This adhesive sheet manufacturing method includes forming an adhesive coating layer by applying an adhesive to a substrate, and forming an adhesive layer by drying the adhesive coating layer.
In one embodiment, the product of drying temperature and drying time when drying the pressure-sensitive adhesive coating layer is 100° C.·min to 500° C.·min.
In one embodiment, the pressure-sensitive adhesive contains a solvent, and the boiling point of the solvent is less than 100°C.

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer that consumes less heat energy when forming the pressure-sensitive adhesive layer and that can exhibit excellent adhesive strength.

1 is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention; FIG.

A. Outline of Adhesive Sheet FIG. 1 is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention. The adhesive sheet 100 includes a substrate 10 and an adhesive layer 20 arranged on at least one side of the substrate 10 .

The pressure-sensitive adhesive layer comprises a (meth)acrylic polymer as a base polymer, an isocyanate-based cross-linking agent and/or an epoxy-based cross-linking agent as a cross-linking agent, and a tertiary amino group capable of multidentate coordination as a low-molecular-weight compound. and/or an organotin (IV) compound capable of multidentate coordination (hereinafter also referred to as a multidentate tin (IV) compound), and heat-expandable microspheres including. In addition, in this specification, (meth)acryl means acryl and/or methacryl.

The thermally expandable microspheres can expand at a predetermined temperature. In the pressure-sensitive adhesive layer containing such heat-expandable microspheres, the heat-expandable microspheres are foamed by heating, resulting in irregularities on the pressure-sensitive adhesive surface (that is, the surface of the pressure-sensitive adhesive layer), and the adhesive strength is reduced or lost. . For example, when the pressure-sensitive adhesive sheet of the present invention is used as a sheet for temporarily fixing a workpiece during processing of an electronic component (e.g., printed circuit board), the workpiece is subjected to a predetermined process (e.g., dicing, sealing, etc.). ), the adhesiveness necessary for temporary fixing is exhibited, and when the work piece is peeled off from the adhesive sheet after processing, the adhesive strength is reduced or lost by heating, and good peelability is exhibited. be.

In the present invention, a pressure-sensitive adhesive layer having excellent adhesive strength can be formed by including the low-molecular-weight compound. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present invention can be formed using a solvent having a low boiling point (e.g., less than 100°C, preferably 80°C or less, more preferably 60°C or less). It has excellent adhesive strength even if it is formed using According to the present invention, by using the above-described low-molecular-weight compound, even if the thermal energy applied during the formation of the pressure-sensitive adhesive layer (typically, the thermal energy when volatilizing the solvent from the pressure-sensitive adhesive) is small, the base polymer can be crosslinked. proceeds favorably, and as a result, a pressure-sensitive adhesive layer having high cohesion and excellent adhesiveness is obtained.

According to the present invention, it is possible to form an adhesive layer with less thermal energy consumption by using a low boiling point solvent as described above. A sheet can be provided. It is also possible to use thermally expandable microspheres with a low foaming initiation temperature. Furthermore, it is also possible to provide a pressure-sensitive adhesive sheet in which deterioration of the heat-expandable microspheres is suppressed by heat, and the adhesive sheet is excellent in peelability.

The adhesive strength at 23° C. when the adhesive layer of the adhesive sheet is attached to polyethylene terephthalate is preferably 0.5 N/20 mm or more, more preferably 1 N/20 mm to 20 N/20 mm, and still more preferably It is 2 N/20 mm to 20 N/20 mm, more preferably 4 N/20 mm to 20 N/mm. Within such a range, for example, it is possible to obtain a pressure-sensitive adhesive sheet that is useful as a temporary fixing sheet used in the manufacture of electronic components. As used herein, the adhesive strength is the adhesive strength in a state where the adhesive strength is not reduced due to the expansion of the heat-expandable microspheres, and means the adhesive strength in the state where the heat history of 40° C. or more has not been passed. In addition, adhesive strength refers to adhesive strength measured by a method according to JIS Z 0237:2009 (bonding conditions: one reciprocation of a 2 kg roller, peeling speed (tensile speed): 300 mm/min, peeling angle of 180°).

The adhesive strength when the adhesive layer of the adhesive sheet is attached to polyethylene terephthalate is reduced to 0.3 N/20 mm or less (preferably 0.2 N/20 mm or less, more preferably 0.1 N/20 mm) by heating. preferably lower. The heating temperature is preferably 70°C to 300°C, more preferably 100°C to 280°C.

The adhesive sheet may further include any other appropriate layer. In one embodiment, the pressure-sensitive adhesive sheet further comprises an undercoat layer arranged between the pressure-sensitive adhesive layer and the substrate. If the undercoat layer is provided, it is possible to obtain a pressure-sensitive adhesive sheet having excellent conformability to adherends. When the pressure-sensitive adhesive layer containing heat-expandable microspheres is heated, the heat-expandable microspheres expand and deform due to the expansion of the heat-expandable microspheres. Therefore, peelability is improved. In addition, another adhesive layer may be provided on the opposite side of the substrate from the adhesive layer. of pressure-sensitive adhesive layers in this order.

The thickness of the adhesive sheet is preferably 3 µm to 300 µm, more preferably 5 µm to 150 µm, and even more preferably 10 µm to 100 µm.

B. Adhesive layer B-1. (Meth)acrylic polymer The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed from an acrylic pressure-sensitive adhesive, that is, contains a (meth)acrylic polymer as a base polymer as described above. The (meth)acrylic polymer may be a polymer (homopolymer or copolymer) using one or more of (meth)acrylic acid alkyl esters as monomer components. The content of the (meth)acrylic polymer is preferably 70 parts by weight or more, more preferably 90 parts by weight or more, and still more preferably 95 parts by weight or more with respect to 100 parts by weight of the polymer in the pressure-sensitive adhesive layer. and particularly preferably 100 parts by weight.

Specific examples of the (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, ( isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, (meth)acrylic acid Octyl, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (meth)acrylic undecyl acid, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, (meth)acrylic acid Examples include (meth)acrylic acid C1-20 alkyl esters such as octadecyl, nonadecyl (meth)acrylate and eicosyl (meth)acrylate. Among them, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 20 carbon atoms (more preferably 6 to 20, particularly preferably 8 to 18 carbon atoms) are more preferable. is 2-ethylhexyl (meth)acrylate.

The (meth)acrylic polymer contains a structural unit having an active hydrogen group. A (meth)acrylic polymer containing a structural unit having an active hydrogen group can be preferably crosslinked during formation, and by using such a polymer, a pressure-sensitive adhesive layer with excellent adhesiveness can be formed at a relatively low temperature. can be done. Examples of active hydrogen groups include hydroxyl groups (alcoholic hydroxyl groups, phenolic hydroxyl groups), carboxyl groups, amino groups, and the like. A hydroxyl group and/or a carboxyl group are particularly preferred. The number of active hydrogen groups contained in the (meth)acrylic polymer may be one, or two or more. Structural units having an active hydrogen group include, for example, structural units derived from carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; ) hydroxyethyl acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, (meth)acrylic structural units derived from hydroxyl group-containing monomers such as hydroxyl lauryl acid and (4-hydroxymethylcyclohexyl)methyl methacrylate;

The content of the structural unit derived from the monomer having an active hydrogen group is preferably 0.1% by weight to 40% by weight, more preferably 0.5% by weight, based on the total structural units constituting the acrylic polymer. % to 30% by weight, particularly preferably 1% to 20% by weight.

For the purpose of modifying cohesive strength, heat resistance, crosslinkability, etc., the acrylic polymer may optionally be a unit corresponding to another monomer component copolymerizable with the (meth)acrylic acid alkyl ester. may contain Examples of such monomer components include acid anhydride monomers such as maleic anhydride and itaconic anhydride; styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, Sulfonic acid group-containing monomers such as acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide , N-methylol (meth) acrylamide, N-methylolpropane (meth) (N-substituted) amide monomers such as acrylamide; (meth) aminoethyl acrylate, (meth) acrylate N,N-dimethylaminoethyl, ( (meth) aminoalkyl acrylate-based monomers such as t-butylaminoethyl acrylate; (meth) alkoxyalkyl acrylate-based monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; N- Maleimide-based monomers such as cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; - itaconimide-based monomers such as ethylhexyl itaconimide, N-cyclohexyl itaconimide, N-lauryl itaconimide; ) Acryloyl-8-oxyoctamethylenesuccinimide and other succinimide monomers; vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole , vinyl oxazole, vinyl morpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam and other vinyl monomers; acrylonitrile, methacrylonitrile and other cyanoacrylate monomers; glycidyl (meth)acrylate, etc. Epoxy group-containing acrylic monomers; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methyl (meth) acrylate Glycol-based acrylic ester monomers such as methoxyethylene glycol and methoxypolypropylene glycol (meth)acrylate; heterocycles such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate, halogen atoms, and silicon atoms Acrylic acid ester-based monomers having, etc.; hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol Polyfunctional monomers such as di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate; isoprene, butadiene, Olefin monomers such as isobutylene; vinyl ether monomers such as vinyl ether; These monomer components may be used alone or in combination of two or more.

The acrylic pressure-sensitive adhesive may contain any suitable additive as necessary. The additives include, for example, tackifiers, plasticizers (e.g., trimellitic ester plasticizers, pyromellitic ester plasticizers, etc.), pigments, dyes, fillers, anti-aging agents, conductive materials, and electrification agents. Examples include inhibitors, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

Any appropriate tackifier is used as the tackifier contained in the acrylic pressure-sensitive adhesive. As the tackifier, for example, a tackifier resin is used. Specific examples of the tackifying resin include rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenol-based resin, rosin ester-based resin, etc.), terpene-based tackifying resins (e.g., terpene-based resin, terpene phenolic resin, styrene-modified terpene-based resin, aromatic-modified terpene-based resin, hydrogenated terpene-based resin), hydrocarbon-based tackifying resin (e.g., aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic Hydrocarbon resins (e.g., styrene resins, xylene resins, etc.), aliphatic/aromatic petroleum resins, aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone-indene resins resins, etc.), phenolic tackifying resins (e.g., alkylphenolic resins, xylene-formaldehyde-based resins, resols, novolacs, etc.), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, elastomer-based tackifying resins etc. Among them, rosin-based tackifying resins, terpene-based tackifying resins, and hydrocarbon-based tackifying resins (styrene-based resins, etc.) are preferred. A tackifier may be used alone or in combination of two or more. The amount of the tackifier added is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, relative to 100 parts by weight of the base polymer.

B-2. Cross-Linking Agent As described above, the pressure-sensitive adhesive layer contains a cross-linking agent. As the cross-linking agent, an isocyanate-based cross-linking agent and/or an epoxy-based cross-linking agent is used. By using such a cross-linking agent, a pressure-sensitive adhesive layer with excellent adhesiveness can be formed at a relatively low temperature.

The isocyanate-based cross-linking agent is a compound having an isocyanate group, and specific examples thereof include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; Cyclic isocyanates; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate and xylylene diisocyanate; trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., isocyanate adducts such as the product name "Coronate HX"; When the pressure-sensitive adhesive layer contains an isocyanate-based cross-linking agent, the content of the isocyanate-based cross-linking agent can be set to any appropriate amount depending on the desired adhesive strength. Generally, it is 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight.

The epoxy-based cross-linking agent is a compound having an epoxy group. N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl Ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P" ”), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name “Epiol E-400”), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name “Epiol P-200”), sorbitol polyglycidyl ether ( Nagase ChemteX, product name "Denacol EX-611"), glycerol polyglycidyl ether (Nagase ChemteX, trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (Nagase Chemtex Corporation, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipate diglycidyl ester, o-phthalate diglycidyl ester, triglycidyl-tris(2-hydroxyethyl ) isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. When the pressure-sensitive adhesive layer contains an epoxy-based cross-linking agent, the content of the epoxy-based cross-linking agent can be set to any appropriate amount depending on the desired adhesive strength. Typically, it is 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight.

B-3. Low-molecular compound As described above, the pressure-sensitive adhesive layer is an amino compound having a tertiary amino group capable of multidentate coordination as a low-molecular compound (also referred to as a multidentate amino compound) and/or capable of multidentate coordination. Includes organotin(IV) compounds (also referred to as multidentate tin(IV) compounds). A low-molecular-weight compound is a compound that can function as a catalyst in the cross-linking reaction of the base polymer during the formation of the pressure-sensitive adhesive layer. By using the above low-molecular-weight compound capable of multidentate coordination, the active hydrogen group in the base polymer and the functional group (isocyanate group or epoxy group) of the cross-linking agent can be coordinated to a single molecule at the same time. As a result, a pressure-sensitive adhesive layer having excellent adhesiveness can be formed at a relatively low temperature.

In one embodiment, an amino compound containing at least two tertiary amino groups in the molecule is used as the polydentate amino compound.

Specific examples of polydentate amino compounds include 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7- and triazabicyclo[4.4.0]dec-5-ene. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, 1,4-diazabicyclo[2.2.2]octane is preferably used as the polydentate amino compound. 1,4-Diazabicyclo[2.2.2]octane is liquid at room temperature and has a high boiling point, so it is easy to disperse in the adhesive, and it is difficult to volatilize during the heating process (for example, the drying process of the adhesive coating layer). Advantageous. It is also advantageous in that it has very poor reactivity to heat-expandable microspheres.

In one embodiment, a (meth)acrylic polymer having an alcoholic hydroxyl group (that is, a (meth)acrylic polymer containing a structural unit derived from a monomer having an alcoholic hydroxyl group) and a polydentate amino compound are combined. Used. This is because the alcoholic hydroxyl group has a low ability to dissociate active hydrogen.

Examples of polydentate tin (IV) compounds include dialkyltin (IV) fatty acid esters such as dibutyltin (IV) dilaurate, dibutyltin (IV) dioctate, dioctyltin (IV) dilaurate, and dibutyltin (IV) diacetate; Distannoxane such as -n-butyl-1,3-diacetoxy-distannoxane and tetra-n-butyl-1,3-dichloro-distannoxane. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, dioctyltin (IV) diacetate is preferably used as the polydentate tin (IV) compound. Dioctyltin (IV) diacetate is liquid at room temperature and has a high boiling point, so it is easy to disperse in the adhesive, and is advantageous in that it is difficult to volatilize during the heating process (for example, the process of drying the adhesive coating layer). It is also advantageous in that it has very poor reactivity to heat-expandable microspheres.

In one embodiment, a (meth)acrylic polymer having a carboxyl group and/or a phenolic hydroxyl group (that is, a monomer-derived structural unit having a carboxyl group and/or a monomer having a phenolic hydroxyl group. A (meth)acrylic polymer) and a polydentate tin (IV) compound are used in combination. This is because a carboxyl group or a phenolic hydroxyl group has high hydrogen dissociation ability, and may strongly bond with a polydentate amino compound to terminate the cross-linking reaction.

The content of the amino compound having a tertiary amino group capable of multidentate coordination and the organotin (IV) compound capable of multidentate coordination is preferably 0.001 wt. parts to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and even more preferably 0.05 to 3 parts by weight. Within such a range, a pressure-sensitive adhesive layer having excellent adhesiveness can be formed at a relatively low temperature. If the content of the polydentate amino compound and the polydentate tin (IV) compound is too high, complex formation (pseudo-crosslinking) may occur between these low-molecular-weight compounds and the cross-linking agent, and the desired adhesive strength may not be obtained. . In the present specification, "the content of the amino compound having a tertiary amino group capable of multidentate coordination and the organotin (IV) compound capable of multidentate coordination" refers to the polydentate amino compound and the polydentate It is the total amount of stannous (IV) compounds. Therefore, when the pressure-sensitive adhesive layer does not contain a multidentate tin (IV) compound, "containing an amino compound having a tertiary amino group capable of multidentate coordination and an organic tin (IV) compound capable of multidentate coordination “Amount” is the content of the polydentate amino compound. In addition, when the pressure-sensitive adhesive layer does not contain a polydentate amino compound, "content of an amino compound having a tertiary amino group capable of polydentate coordination and an organotin (IV) compound capable of polydentate coordination" is the content of polydentate tin(IV) compounds.

The boiling point of the low molecular compound is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher. A low-molecular-weight compound with a boiling point in this range is liquid at room temperature and has a high boiling point, so it is easy to disperse in the adhesive, and it is advantageous in that it is difficult to volatilize during the heating process (for example, the process of drying the adhesive coating layer). .

B-4. Thermally Expandable Microspheres As the thermally expandable microspheres, any appropriate thermally expandable microspheres can be used as long as they are microspheres that can be expanded or foamed by heating. As the heat-expandable microspheres, for example, microspheres in which a substance that easily expands by heating is encapsulated in an elastic shell can be used. Such heat-expandable microspheres can be produced by any appropriate method such as coacervation, interfacial polymerization, and the like.

Substances that easily expand when heated include, for example, propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, normal hexane, isohexane, heptane, octane, petroleum ether, methane halides, and tetraalkylsilanes. low boiling point liquid such as; azodicarbonamide gasified by thermal decomposition; and the like.

Examples of substances constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, Carboxylic acid monomers such as citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (Meth)acrylic acid esters such as isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene, chlorostyrene; acrylamide, substituted acrylamide , methacrylamide, substituted methacrylamide, and other amide monomers; A polymer composed of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer, acrylonitrile-methacrylonitrile-itaconic acid copolymer, A polymer etc. are mentioned.

An inorganic foaming agent or an organic foaming agent may be used as the thermally expandable microspheres. Examples of inorganic foaming agents include ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium borohydride, and various azides. Examples of organic foaming agents include chlorofluoroalkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; and azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate. hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, 4,4′-oxybis(benzenesulfonyl hydrazide), allylbis(sulfonyl hydrazide); p-toluylenesulfonyl semicarbazide, 4, Semicarbazide compounds such as 4'-oxybis(benzenesulfonyl semicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N,N'-dinitrosopentamethylenetetramine, N,N' -dimethyl-N,N'-dinitrosoterephthalamide; and other N-nitroso compounds.

The particle size of the heat-expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, even more preferably 10 μm to 20 μm, and particularly preferably 10 μm to 15 μm. . Therefore, the average particle size of the heat-expandable microspheres before heating is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm. The above particle size and average particle size are values determined by a particle size distribution measurement method in a laser scattering method.

It is preferable that the thermally expandable microspheres have an appropriate strength such that they do not burst until the volume expansion coefficient is preferably 5 times or more, more preferably 7 times or more, and still more preferably 10 times or more. When such heat-expandable microspheres are used, the adhesive strength can be efficiently reduced by heat treatment.

The expansion start temperature of the heat-expandable microspheres is preferably 80°C to 250°C, more preferably 80°C to 230°C, still more preferably 80°C to 200°C, still more preferably 80°C to 150°C, particularly preferably 80°C to 120°C, most preferably 80°C to 100°C. In this specification, the expansion start temperature of the thermally expandable microspheres means that the adhesive layer thickness (when an undercoat layer is arranged, the sum of the undercoat layer thickness and the adhesive layer thickness) is 5% or more thicker than at room temperature. means the lowest temperature For example, the foaming initiation temperature can correspond to the temperature at which the adhesive force of the adhesive tape becomes 1.0 N/20 mm or less and 50% or less of the initial adhesive force.

The content of the heat-expandable microspheres in the pressure-sensitive adhesive layer can be appropriately set according to the desired decrease in adhesive force. The content of the thermally expandable microspheres is, for example, 1 part by weight to 150 parts by weight, preferably 10 parts by weight to 130 parts by weight, more preferably 100 parts by weight of the base polymer forming the pressure-sensitive adhesive layer. is 25 to 100 parts by weight.

The arithmetic surface roughness Ra of the adhesive layer before the thermally expandable microspheres are expanded (that is, before heating) is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less.

The thickness of the adhesive layer is preferably 5 μm to 70 μm, more preferably 10 μm to 60 μm, still more preferably 15 μm to 55 μm, most preferably 20 μm to 50 μm.

C. Substrate The substrate may be composed of any suitable material. Various sheet materials such as plastic film, plastic sheet, paper, cloth, nonwoven fabric, metal foil, a plastic laminate thereof, and a laminate of plastics can be used as the base material. Among them, plastic films and plastic sheets (hereinafter referred to as plastic films) are most preferable from the viewpoint of handling and cost. The material for the plastic film can be selected according to need from the viewpoint of strength, heat resistance, and the like. For example, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) and other α-olefin-based resins as monomer components; polyethylene terephthalate (PET), polyethylene Polyesters such as naphthalate (PEN) and polybutylene terephthalate (PBT); polyvinyl chloride (PVC); polyphenylene sulfide (PPS); amide resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); Ketone (PEEK), polyimide, polyetherimide, polystyrene, acrylic resin and the like. These materials can be used alone or in combination of two or more. Moreover, as the plastic film, any of an unstretched film, a uniaxially oriented film, and a biaxially oriented film may be used. In addition, these films may be laminated films composed of two or more film layers, or films to which a lubricant such as inert particles is appropriately added may be used from the viewpoint of handleability.

The thickness of the substrate is preferably 200 μm or less, more preferably 1 μm to 200 μm, still more preferably 5 μm to 200 μm, particularly preferably 10 μm to 200 μm, particularly preferably 20 μm to 200 μm, Most preferred is 30 μm to 200 μm.

The base material may be surface-treated. Examples of surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage shock exposure, ionizing radiation treatment, and coating treatment with a primer.

D. Undercoat Layer The undercoat layer contains any suitable adhesive. Examples of the adhesive that constitutes the undercoat layer include acrylic adhesives, rubber adhesives, silicone adhesives, and the like. Among them, an acrylic pressure-sensitive adhesive can be preferably used. As the adhesive, an active energy ray-curable acrylic adhesive (hereinafter referred to as an active energy ray-curable adhesive) may be used. Preferably, the same pressure-sensitive adhesive as that constituting the above-described pressure-sensitive adhesive layer is used as the pressure-sensitive adhesive that constitutes the undercoat layer. In addition, the undercoat layer may be an organic substance exhibiting rubber-like elasticity other than those shown above. Therefore, it is sometimes called a rubber-like organic elastic body.

The thickness of the undercoat layer is preferably 1 μm to 100 μm, more preferably 1 μm to 80 μm, still more preferably 1 μm to 60 μm, still more preferably 1 μm to 40 μm, particularly preferably 5 μm to 35 μm. , most preferably between 10 μm and 30 μm. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet which is excellent in liner peeling operability and in which the effect of heating the thermally expandable microspheres on the substrate side is suppressed.

The elastic modulus of the undercoat layer is preferably 0.001 MPa to 10 MPa, more preferably 0.01 MPa to 8 MPa, and more preferably 0.5 MPa to 5 MPa. As used herein, the elastic modulus means the elastic modulus measured by the nanoindentation method in a 23° C. environment. The elastic modulus by the nanoindentation method is the load applied to the indenter and the depth of indentation when the indenter (triangular pyramid type) is pushed into the sample (indentation speed: 1000 nm / sec, indentation depth: 800 nm). , refers to the elastic modulus obtained from the applied load-indentation depth curve obtained by measuring continuously during unloading.

E. Separate Adhesive Layer The separate adhesive layer may contain any suitable adhesive. Examples of adhesives constituting another adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, and the like. As the adhesive, an active energy ray-curable acrylic adhesive (hereinafter referred to as an active energy ray-curable adhesive) may be used. Details of the adhesive are described, for example, in JP-A-2015-168711. The description of the publication is incorporated herein by reference.

F. Production Method of Adhesive Sheet The above-mentioned adhesive sheet can be produced by any appropriate method. As a method for producing an adhesive sheet, for example, a method of coating (applying and drying) an adhesive directly on a substrate, or a method of coating (applying and drying) an adhesive onto any appropriate substrate. A method of transferring the applied coating layer to the substrate, and the like. When the pressure-sensitive adhesive sheet has the undercoat layer, the undercoat layer can be formed, for example, by applying a composition (adhesive) for forming the undercoat layer onto the base material or the pressure-sensitive adhesive layer. .

In one embodiment, a method for producing a pressure-sensitive adhesive sheet includes forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive to a substrate, and drying the pressure-sensitive adhesive layer to form a pressure-sensitive adhesive layer. including doing

The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer comprises the (meth)acrylic polymer as the base polymer, the cross-linking agent, and the multidentate amino compound and/or the multidentate tin (IV) compound as the low-molecular-weight compound. , and the heat-expandable microspheres described above. Typically, the adhesive further contains any suitable solvent.

A solvent having a boiling point of less than 100°C is preferably used as the solvent. The pressure-sensitive adhesive sheet of the present invention can exhibit sufficient pressure-sensitive adhesive strength even when a solvent having a relatively low boiling point is used and the pressure-sensitive adhesive coating layer is dried at a low temperature. In such a pressure-sensitive adhesive sheet, energy consumption during production can be suppressed. In addition, in the pressure-sensitive adhesive sheet, deterioration of the heat-expandable microspheres can be prevented, and the peelability is also excellent. As the solvent, a non-aromatic hydrocarbon solvent can be preferably used. The non-aromatic hydrocarbon-based solvent may be a solvent comprising one non-aromatic hydrocarbon solvent, or may be a solvent comprising two or more non-aromatic hydrocarbon solvents. Moreover, the non-aromatic hydrocarbon solvent may contain a solvent other than the non-aromatic hydrocarbon solvent. Examples of non-aromatic hydrocarbon solvents include aliphatic hydrocarbons such as cyclone and heptane; halogen-containing hydrocarbons such as methylene chloride and chloroform; ketones such as acetone, ethyl acetate and 2-butanone; Cyclic ether etc. are mentioned. Among them, ethyl acetate or 2-butanone is preferred.

Examples of the method of applying the adhesive include a method using a die coater, a comma coater, a gravure coater, and the like. Heat drying is preferably employed as the drying method. For example, drying can be performed by placing the adhesive coating layer in a dryer equipped with a blower capable of forcibly convecting air at a predetermined temperature for an arbitrary period of time.

The drying temperature is preferably 55°C or higher and lower than 100°C, more preferably 60°C to 90°C, even more preferably 65°C to 90°C. Within such a range, the pressure-sensitive adhesive layer can be efficiently formed, and unnecessary foaming of the heat-expandable microspheres and deterioration of the heat-expandable microspheres can be prevented. Moreover, a pressure-sensitive adhesive layer having a preferable surface shape can be formed. The drying temperature may be changed stepwise. For example, the drying temperature may be increased over time to form the pressure-sensitive adhesive layer.

The drying time can be any appropriate time depending on the pressure-sensitive adhesive layer composition, drying temperature, and the like. The drying time is, for example, 1 minute to 10 minutes. Within such a range, the pressure-sensitive adhesive layer can be efficiently formed.

The drying process may be controlled by the product of the drying temperature and the drying time when drying the adhesive coating layer. The product of drying temperature and drying time is preferably 100° C.·min to 500° C.·min, more preferably 100° C.·min to 350° C.·min. Within such a range, a pressure-sensitive adhesive layer having excellent adhesiveness can be efficiently formed.

G. Uses The pressure-sensitive adhesive sheet can be preferably used as a temporary fixing sheet when processing any appropriate member (for example, electronic parts such as semiconductor chips). In one embodiment, the pressure-sensitive adhesive sheet can be used as a sheet for temporarily fixing a semiconductor chip when manufacturing a CSP (Chip Size/Scale Package) or a WLP (Wafer Level Package).

In one embodiment, the adhesive sheet is roll-shaped.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. In the examples, "parts" and "%" are by weight unless otherwise specified.
In addition, in this specification, the expansion start temperature of the thermally expandable microspheres is determined by the following method.
On a hot plate (Shamal hot plate “HHP-411”) set to a predetermined temperature, the adhesive sheet is sandwiched between 10 mm thick heat-resistant glass plates (140 mm × 140 mm) set to the same temperature as the predetermined temperature described later. After heating for one minute, it is cooled to room temperature, and the lowest temperature at which the adhesive layer thickness measured with a dial gauge becomes 5% or more thicker than the thickness before heating is taken as the foaming start temperature of the thermally expandable microspheres. Here, the predetermined temperature is a temperature set in increments of 5°C starting from 50°C (that is, 50°C, 55°C, 60°C, and so on), and each time the predetermined temperature is changed, the adhesive sheet is renewed. to use. In addition, the adhesive layer whose thickness is measured is the adhesive layer (containing thermally expandable microspheres), and when the undercoat layer (rubber-like organic elastic layer) is present, shall be measured including
The expansion initiation temperature of thermally expandable microspheres F-36D and F-50D measured by this method is 85°C and 105°C, respectively.

[Production Example 1] Production of base polymer 1 In ethyl acetate, 100 parts of 2-ethylhexyl acrylate (EHA), 1 part of methyl methacrylate (MMA), 4 parts of 2-hydroxyethylhexyl acrylate (HEA), and a polymerization initiator were mixed. After adding 0.2 parts of benzoyl peroxide as a solution, the mixture was heated to obtain an ethyl acetate solution of an acrylic copolymer (polymer 1).

[Production Example 2] Production of base polymer 2 In ethyl acetate, 65 parts of ethyl acrylate (EA), 5 parts of butyl acrylate (BA), 30 parts of 2-ethylhexyl acrylate (EHA), and 5 parts of methyl methacrylate (MMA) were mixed. 3 parts of 2-hydroxyethylhexyl acrylate (HEA) and 0.2 parts of benzoyl peroxide as a polymerization initiator were added, followed by heating to obtain an ethyl acetate solution of an acrylic copolymer (polymer 2). rice field.

[Production Example 3] Production of base polymer 3 90 parts of 2-ethylhexyl acrylate (EHA), 5 parts of acrylic acid (AA), and 0.2 parts of benzoyl peroxide as a polymerization initiator were added to ethyl acetate. After that, it was heated to obtain an ethyl acetate solution of an acrylic copolymer (polymer 3).

[Production Example 4] Production of Base Polymer 4 65 parts of ethyl acrylate (EA), 5 parts of butyl acrylate (BA), 30 parts of 2-ethylhexyl acrylate (EHA), and methyl methacrylate (MMA) in 2-butanone. 5 parts, 10 parts of 2-hydroxyethylhexyl acrylate (HEA), and 0.2 parts of benzoyl peroxide as a polymerization initiator were added, followed by heating to obtain an ethyl acetate solution of an acrylic copolymer (polymer 4). Obtained.

[Production Example 5] Production of base polymer 5 In toluene, 100 parts of 2-ethylhexyl acrylate (EHA), 1 part of methyl methacrylate (MMA), 4 parts of 2-hydroxyethylhexyl acrylate (HEA), and as a polymerization initiator After adding 0.2 parts of benzoyl peroxide, the mixture was heated to obtain a toluene solution of an acrylic copolymer (polymer 5).

[Production Example 6] Production of base polymer 6 In toluene, 65 parts of ethyl acrylate (EA), 5 parts of butyl acrylate (BA), 30 parts of ethylhexyl acrylate (EHA), and 3 parts of 2-hydroxyethylhexyl acrylate (HEA) were mixed. 5 parts and 0.2 parts of benzoyl peroxide as a polymerization initiator were added, and then heated to obtain a toluene solution of an acrylic copolymer (polymer 6).

[Production Example 7] Production of base polymer 7 In toluene, 70 parts of ethyl acrylate (EA), 3 parts of butyl acrylate (BA), 30 parts of ethylhexyl acrylate (EHA), 5 parts of methyl methacrylate (MMA), After adding 3.5 parts of 2-hydroxyethylhexyl acrylate (HEA) and 0.2 parts of benzoyl peroxide as a polymerization initiator, the mixture was heated to obtain a toluene solution of an acrylic copolymer (polymer 7). .

[Example 1]
(Preparation of undercoat layer/substrate laminate)
A toluene solution of polymer 6 (polymer 6: 100 parts), 1.5 parts of an isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and 0.05 parts of dioctyltin dilaurate are mixed and mixed. A solution A was prepared.
The mixed solution A was applied to one surface of a substrate (manufactured by Toray Industries, Inc., product name “Lumirror S10”, thickness: 25 μm) using an applicator so that the thickness after solvent evaporation (drying) was 13 μm. . Thereafter, the solvent was volatilized (dried) at 150° C. for 1 minute using a forced convection hot air drying oven to obtain an undercoat layer/substrate laminate.
(Preparation of MRF38 (liner)/adhesive layer (containing thermally expandable microspheres) laminate)
An ethyl acetate solution of polymer 1 (polymer 1: 100 parts), an isocyanate cross-linking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L") 1.5 parts, and a polydentate amino compound (1,4-diazabicyclo [2 .2.2] octane, manufactured by Sigma-Aldrich) 0.01 part, tackifying resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name "Sumilite PR12603") 10 parts, and thermally expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., A pressure-sensitive adhesive (mixed solution B) was prepared by mixing 30 parts of the product name “F36-D”, foaming initiation temperature: 85° C., average particle size: 13 μm.
A liner coated with a silicone-based release agent (PET film, manufactured by Mitsubishi Plastics, Inc., product name “MRF-38”) was coated with the release agent so that the thickness after the solvent volatilization (drying) was 35 μm. The adhesive (mixed solution B) was applied. Thereafter, the solvent was volatilized (dried) at 65° C. for 5 minutes using a forced convection hot air drying oven to obtain an MRF38 (liner)/adhesive layer (containing thermally expandable microspheres) laminate.
(Preparation of MRF38 (liner)/adhesive layer (containing heat-expandable microspheres)/undercoat layer/substrate laminate)
MRF38 (liner)/adhesive layer (containing thermally expandable microspheres) and undercoat layer/substrate laminate are laminated so that the adhesive layer (containing thermally expandable microspheres) and the undercoat layer face each other. Thus, a laminate of MRF38 (liner)/adhesive layer (containing heat-expandable microspheres)/undercoat layer/substrate was obtained.
(MRF50 (liner)/manufacture of another pressure-sensitive adhesive layer laminate)
A toluene solution of polymer 7 (polymer 7: 100 parts), 1.5 parts of an isocyanate cross-linking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and a plasticizer (manufactured by DIC, trade name "Monocizer W700") ”) and 0.05 part of dioctyltin dilaurate to prepare a mixed solution C.
A liner coated with a silicone-based release agent (PET film, manufactured by Mitsubishi Plastics, Inc., trade name “MRF-38”) was coated with the release agent so that the thickness after solvent volatilization (drying) was 7 μm. The mixed solution C was applied. Thereafter, the solvent was volatilized (dried) at 150° C. for 1 minute using a forced convection hot air drying oven to obtain MRF50 (liner)/another adhesive layer laminate.
(Preparation of adhesive sheet with liner)
MRF38 (liner)/adhesive layer (containing thermally expandable microspheres)/undercoat layer/substrate laminate and MRF50 (liner)/another adhesive layer laminate were combined with the substrate and another adhesive layer. are facing each other, and a liner-attached pressure-sensitive adhesive sheet (MRF38 (liner) / pressure-sensitive adhesive layer (containing thermally expandable microspheres) / undercoat layer / base material / another pressure-sensitive adhesive layer / MRF50 (liner)) Obtained.

[Examples 2 to 5, Comparative Examples 1 to 4]
When forming the pressure-sensitive adhesive layer, the base polymer shown in Table 1 was used (in Example 5, a 2-butanone solution of polymer 4 was used, and in Comparative Examples 2 and 3, a toluene solution of polymer 5 was used), The low-molecular compound shown in Table 1 was used in the amount shown in Table 1, the crosslinking agent shown in Table 1 was used in the amount shown in Table 1, the thermally expandable microspheres shown in Table 1 were used in the amount shown in Table 1, and the amount shown in Table 1 was used. A pressure-sensitive adhesive sheet with a liner was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive coating layer was dried at the temperature and time shown in 1. The heat-expandable microspheres “F-50D” are trade name “F-50D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. (expansion initiation temperature: 105° C., average particle size: 14 μm). The cross-linking agent “TC” is an epoxy-based cross-linking agent (Mitsubishi Gas Chemical Co., Ltd., trade name “Tetrad C”).

[Example 6]
A pressure-sensitive adhesive sheet with a liner was obtained in the same manner as in Example 1, except that the undercoat layer did not contain dioctyltin dilaurate.

<Evaluation>
After peeling off the liner from the liner-attached pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, the pressure-sensitive adhesive sheets were subjected to the following evaluations. Table 1 shows the results. Comparative Example 1 cannot be evaluated due to cohesive failure of the pressure-sensitive adhesive layer, which is considered to be caused by insufficient cross-linking of the base polymer. Comparative Example 3 cannot be evaluated because the thermally expandable microspheres foamed during production. became.

(1) Adhesive strength The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 20 mm in width and 140 mm in length.
On the adhesive layer side of the adhesive sheet, a polyethylene terephthalate film (trade name “Lumirror S-10” manufactured by Toray Industries, Inc.; thickness: 25 μm, width: 30 mm) as an adherend was protruded in the width direction by 5 mm on each side. , and JIS Z 0237:2009, a 2-kg roller was reciprocated once to bond them together.
A measurement sample was prepared by bonding a metal plate (SUS304 plate, thickness 3 mm) to another adhesive layer side via a double-sided tape (manufactured by Nitto Denko Co., Ltd., trade name “No. 500”).
After that, the adherend was peeled off from the adhesive sheet in the longitudinal direction under the conditions of a peeling angle of 180° and a peeling speed (tensile speed) of 300 mm/min. The maximum value of the load excluding the peak top at the initial stage of measurement) was obtained, and this maximum load was divided by the tape width to obtain the adhesive strength (N/20 mm width). The above operation was performed in an atmosphere at a temperature of 23°C.
Excellent when the adhesive strength is 4 N / 20 mm or more (◎ in the table), good when it is 2 N / 20 mm or more and less than 4 N / 20 mm (○ in the table), 0.5 N / 20 mm or more and less than 2 N / 20 mm A certain case was rated as acceptable (Δ in the table), and a case of less than 0.5 N/20 mm was rated as unacceptable (× in the table).

(2) Thermal Peelability Evaluation The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 20 mm in width and 140 mm in length.
A metal plate (SUS304 plate, thickness 3 mm, width 30 mm, length 160 mm) is placed as an adherend on the adhesive layer side of the adhesive sheet, and the adhesive sheet and the metal plate are pasted by reciprocating a 2 kg roller once. Together, they were used as evaluation samples.
A 10 mm thick heat-resistant glass plate (140 mm x 140 mm) was placed on a hot plate (Shamal hot plate "HHP-411") set at 120°C, and the heat-resistant glass plate was heated to 120°C.
The sample was placed on a hot plate (Shamal hot plate "HHP-411") set to 120 ° C with the adhesive sheet facing upward, and the heat-resistant glass plate set at 120 ° C was placed on the adhesive sheet ( That is, a laminated structure of hot plate/metal plate/adhesive sheet/glass plate was used).
The time until the adhesive layer was peeled off (separated) from the SUS plate was measured.
The time required for separation is excellent if it is within 3 minutes (◎ in the table), good if it is over 3 minutes and within 7 minutes (○ in the table), and over 7 minutes but within 10 minutes. was rated as acceptable (Δ in the table), and as unacceptable (x in the table) when 10 minutes or more or no separation occurred.

REFERENCE SIGNS LIST 10 base material 20 adhesive layer 100 adhesive sheet

Claims

comprising a substrate and an adhesive layer disposed on at least one side of the substrate;
The pressure-sensitive adhesive layer is
a (meth)acrylic polymer as a base polymer;
an isocyanate-based cross-linking agent and/or an epoxy-based cross-linking agent as a cross-linking agent;
an amino compound having a tertiary amino group capable of multidentate coordination and/or an organotin (IV) compound capable of multidentate coordination as a low-molecular-weight compound;
and heat-expandable microspheres,
The (meth)acrylic polymer comprises a structural unit having an active hydrogen group,
adhesive sheet.
The content of the amino compound having a tertiary amino group capable of multidentate coordination and the organotin (IV) compound capable of multidentate coordination is 0.001 part by weight with respect to 100 parts by weight of the base polymer. The pressure-sensitive adhesive sheet according to claim 1, which is ~10 parts by weight.
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the amino compound having a tertiary amino group capable of multidentate coordination is an amino compound containing at least two tertiary amino groups in the molecule.
The amino compound having a tertiary amino group capable of multidentate coordination is 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene and 3. The pressure-sensitive adhesive sheet according to claim 1, which is at least one member selected from the group consisting of 1,5,7-triazabicyclo[4.4.0]dec-5-ene.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the organic tin (IV) compound capable of multidentate coordination is a dialkyltin (IV) fatty acid ester.
The organotin (IV) compound capable of multidentate coordination is at least one selected from the group consisting of dibutyltin (IV) dilaurate, dibutyltin (IV) dioctate, dioctyltin (IV) dilaurate and dibutyltin (IV) diacetate. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the active hydrogen groups are hydroxyl groups and/or carboxyl groups.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the thermally expandable microspheres have a foaming temperature of 80°C to 250°C.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, further comprising another pressure-sensitive adhesive layer on the opposite side of the base material to the pressure-sensitive adhesive layer.
Applying an adhesive to a substrate to form an adhesive coating layer; and
Forming an adhesive layer by drying the adhesive coating layer,
A method for producing the pressure-sensitive adhesive sheet according to any one of claims 1 to 9.
The method for producing an adhesive sheet according to claim 10, wherein the product of the drying temperature and the drying time when drying the adhesive coating layer is 100°C·min to 500°C·min.
The adhesive contains a solvent,
The boiling point of the solvent is less than 100°C.
The method for producing the pressure-sensitive adhesive sheet according to claim 10 or 11.