JP2005105028A - Thermally conductive pressure-sensitive adhesive composition, thermally conductive sheet-like molded article, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a heat conductive pressure-sensitive adhesive composition having sufficient pressure-sensitive adhesion, especially excellent balance among hardness, pressure-sensitive adhesion and shape retention properties and sufficient heat conductivity, and to prepare a heat conductive pressure-sensitive adhesive sheet. <P>SOLUTION: The heat conductive pressure-sensitive adhesive composition comprises an acrylic or a methacrylic ester copolymer prepared by polymerizing a monomer mixture composed of specific amounts of an acrylic or a methacrylic ester monomer, a monomer having an organic acid group and a monomer copolymerizable therewith, respectively, in the presence of a specified (meth)acrylic ester copolymer and in the presence of a thermal polymerization initiator and an internal crosslinking agent having ≥2 polymerizable unsaturated bonds and a heat conductive inorganic compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat conductive pressure-sensitive adhesive composition, a heat conductive sheet-like molded body comprising the same, and a method for producing a heat conductive sheet-like molded body.

In recent years, electronic components such as plasma display panels (PDP), integrated circuit (IC) chips, and the like have increased in heat generation as their performance has increased. As a result, there is a need to take measures against functional failures due to temperature rise. In general, a method of diffusing heat by attaching a heat sink such as a heat sink, a heat radiating metal plate, or a heat radiating fin to a heat generating body such as an electronic component is employed. Various types of heat conductive sheets are used to efficiently conduct heat from the heat generating element to the heat radiating element. In general, a pressure-sensitive adhesive sheet is required for fixing the heat generating element and the heat radiating element. .
Patent Document 1 discloses a thermally conductive electrical insulation containing a polymer from a monomer containing a polar monomer copolymerizable with (meth) acrylic acid alkyl ester and thermally conductive electrically insulating particles (thermally conductive filler). A pressure sensitive adhesive is disclosed. Specifically, a pressure sensitive adhesive is obtained by photopolymerization by adding a crosslinking agent such as acrylic acid, alumina and tripropylene glycol diacrylate to polyisooctyl acrylate syrup.
In Patent Document 2, a monomer mixture containing (meth) acrylic acid alkyl ester as a main component and not containing a polar group-containing monomer, a photopolymerization initiator, a polyfunctional (meth) acrylate as a cross-linking agent, and A thermally conductive pressure sensitive adhesive comprising a photopolymer of a mixture of thermally conductive fillers is disclosed.
The pressure-sensitive adhesives disclosed in these documents are difficult to balance between hardness and pressure-sensitive adhesiveness, and in reality, because photopolymerization is required, equipment for that is necessary, It is hard to say that it is economically advantageous.

Patent Document 3 discloses a heat conductive pressure-sensitive adhesive obtained by blending heat conductive particles with a copolymer of an alkyl (meth) acrylate and a vinyl monomer that satisfies a specific formula. The specific vinyl monomer used here is preferably a special one such as (meth) acrylate having a phosphoric acid group or 2-hydroxy-3-phenoxypropyl acrylate.
Furthermore, Patent Document 4 discloses a heat formed by blending an acrylic ester polymer obtained by copolymerizing a polar monomer having a glass transition temperature of 0 ° C. or less as a homopolymer with a thermally conductive filler having a specific polarity. A conductive pressure sensitive adhesive is disclosed. The pressure sensitive adhesive disclosed here needs to select a filler corresponding to the copolymerized polar monomer.
In these methods, in order to obtain a corresponding effect, a large amount of special monomers must be used, which is not economically advantageous, and it is necessary to balance hardness and pressure-sensitive adhesiveness. There is a problem that is difficult.
The present applicant has proposed a pressure-sensitive adhesive composition containing a (meth) acrylate-based polymer having a specific solvent solubility as a solution to these problems of the prior art (Patent Document 5). After all, it has been found that it is difficult to maintain a sufficiently good balance between hardness and pressure-sensitive adhesiveness.

  In addition, heat-conductive pressure-sensitive adhesives are often wound in a roll in a state of being temporarily attached to a release paper or polyester film, stored in a warehouse, and transported. The inside of the transport vehicle (ship) may reach a high temperature of about 50 ° C. At that time, the heat conductive pressure-sensitive adhesive sheet is deformed by heat and pressure due to the weight of the roll-shaped scroll, and the shape cannot be maintained and the end of the scroll It turned out that it was easy to sag.

JP-A-6-88061 Japanese Patent Laid-Open No. 10-324853 JP 2002-322449 A WO98 / 24860 publication JP 2002-285121 A

  As described above, a great deal of research has been conducted on the heat-conductive pressure-sensitive adhesive, but it has sufficient pressure-sensitive adhesiveness, good operability and transportability, and has no economic problems. Nothing has yet been found, and in particular, a product having an excellent balance of hardness, pressure-sensitive adhesiveness, and shape retention has not been obtained.

  Therefore, an object of the present invention is to provide a heat-conductive pressure-sensitive adhesive having a sufficient pressure-sensitive adhesive property, in particular, having a good balance between hardness, pressure-sensitive adhesive property, and shape retention, and having a sufficient thermal conductivity. An agent composition and a heat conductive pressure sensitive adhesive sheet are provided.

  As a result of continual research on the heat conductive pressure-sensitive adhesive composition, the present inventors have adopted a specific polymerization method to have a specific structure when synthesizing a (meth) acrylic acid ester copolymer ( The inventors have found that the object can be achieved by obtaining a (meth) acrylic acid ester copolymer and using it as a pressure sensitive adhesive, and based on this finding, the present invention has been completed.

Thus, according to the present invention, the unit derived from the (meth) acrylic acid ester monomer (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, 80 to 99.9% by weight, an organic acid group Derived from monomer unit (a2) containing 0.1 to 20% by weight, monomer unit containing functional group other than organic acid group (a3) from 0 to 10% by weight and monomers copolymerizable therewith In the presence of 100 parts by weight of the copolymer (A1) containing 0 to 10% by weight of the monomer unit (a4), a homopolymer having a glass transition temperature of −20 ° C. or lower is formed (meta ) Acrylic acid ester monomer (a5m) 70-99.9% by weight, monomer having organic acid group (a6m) 0.1-10% by weight, and monomer copolymerizable therewith (a7m) 20 to 65 parts by weight of a monomer mixture (A2m) consisting of 0 to 20% by weight 0.05 to 20 parts by weight of the thermal polymerization initiator (B2) and 0.1 to 20 parts by weight of an internal crosslinking agent having two or more polymerizable unsaturated bonds with respect to 100 parts by weight of the body mixture (A2m) Thermally conductive pressure-sensitive adhesive comprising 100 parts by weight of (meth) acrylic acid ester copolymer (A) obtained by polymerization in the presence of (C2) and 50 to 250 parts by weight of thermally conductive inorganic compound (D) An agent composition is provided.
In the heat conductive pressure-sensitive adhesive composition of the present invention, the heat conductive inorganic compound (D) is preferably aluminum hydroxide.
Moreover, according to this invention, the heat conductive sheet-like molded object which consists of a heat conductive pressure-sensitive-adhesive composition of this invention is provided.
Moreover, according to this invention, the heat conductive sheet-like molded object which consists of a base material and the heat conductive pressure-sensitive-adhesive composition layer of this invention formed in the single side | surface or both surfaces is provided.

Furthermore, according to the present invention, the unit derived from a (meth) acrylic acid ester monomer (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, 80 to 99.9% by weight, an organic acid group Derived from monomer unit (a2) containing 0.1 to 20% by weight, monomer unit containing functional group other than organic acid group (a3) from 0 to 10% by weight and monomers copolymerizable therewith (Meth) acrylic acid ester forming a homopolymer having a glass transition temperature of −20 ° C. or less, 100 parts by weight of copolymer (A1) containing 0 to 10% by weight of monomer unit (a4) Monomer (a5m) 70-99.9% by weight, monomer having organic acid group (a6m) 0.1-10% by weight, and monomer copolymerizable with these (a7m) 0-20% % Monomer mixture (A2m) 20-65 parts by weight, monomer mixture (A2 ) 0.05 to 20 parts by weight of thermal polymerization initiator (B2), 0.1 to 20 parts by weight of an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and 100 parts by weight; 50 to 250 parts by weight of the thermally conductive inorganic compound (D) is mixed, heated and sheeted with respect to a total of 100 parts by weight of the copolymer (A1) and the monomer mixture (A2m). A method for producing a thermally conductive sheet-like molded body is provided.
In one embodiment of the present invention, the thermally conductive sheet-like molded article comprises a copolymer (A1), a monomer mixture (A2m), a thermal polymerization initiator (B2), and two or more polymerizable unsaturated bonds. It can be obtained by mixing the internal cross-linking agent (C2) and the heat conductive inorganic compound (D), and then forming a sheet under heating.

  The heat conductive pressure-sensitive adhesive composition of the present invention has sufficient pressure-sensitive adhesiveness, in particular, has a good balance between hardness, pressure-sensitive adhesiveness, and shape retention, and has sufficient heat conductivity. Have. Therefore, the heat conductive sheet-like molded body obtained from this is useful as a heat conductive sheet for efficiently conducting heat conduction from a heat generating body such as an electronic component such as a plasma display panel (PDP) to a heat radiating body.

Hereinafter, the present invention will be described in detail.
The heat conductive pressure sensitive adhesive composition of this invention contains a (meth) acrylic acid ester copolymer (A) as a 1st essential component. The (meth) acrylic acid ester copolymer (A) is a unit derived from a (meth) acrylic acid ester monomer (a1) 80 to 99.9 that forms a homopolymer having a glass transition temperature of −20 ° C. or lower. % By weight, monomer unit having organic acid group (a2) 0.1 to 20% by weight, monomer unit having functional group other than organic acid group (a3) 0 to 10% by weight, and copolymerized therewith Monomer weight with a glass transition temperature of −20 ° C. or lower in the presence of 100 parts by weight of copolymer (A1) containing 0 to 10% by weight of monomer units (a4) derived from possible monomers (Meth) acrylic acid ester monomer (a5m) 70 to 99.9% by weight, monomer having organic acid group (a6m) 0.1 to 10% by weight, and copolymerizable with these Monomer mixture (A2m) 20 consisting of 0 to 20% by weight of monomer (a7m) 20 65 parts by weight of 0.05 to 20 parts by weight of the thermal polymerization initiator (B2) and 0.1 to 20 parts by weight of two or more polymerizable non-polymerizable components with respect to 100 parts by weight of the monomer mixture (A2m). It is obtained by polymerization in the presence of an internal crosslinking agent (C2) having a saturated bond.
In the present invention, (meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester.

The copolymer (A1) used to obtain the (meth) acrylic acid ester copolymer (A) forms a homopolymer having a glass transition temperature of −20 ° C. or less. Body-derived unit (a1) 80 to 99.9% by weight, monomer unit having organic acid group (a2) 0.1 to 20% by weight, monomer unit containing functional group other than organic acid group ( a3) 0 to 10% by weight and a monomer unit derived from a monomer copolymerizable therewith (a4) containing 0 to 10% by weight.
There is no particular limitation on the (meth) acrylate monomer (a1m) that gives the (meth) acrylate monomer unit (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or less. However, for example, ethyl acrylate (the glass transition temperature of the homopolymer is -24 ° C), n-propyl acrylate (-37 ° C), n-butyl acrylate (-54 ° C), sec-acrylic acid Butyl (-22 ° C), n-pentyl acrylate (-60 ° C), n-hexyl acrylate (-61 ° C), n-octyl acrylate (65 ° C), 2-ethylhexyl acrylate ( -50 ° C), 2-methoxyethyl acrylate (-50 ° C), 3-methoxypropyl acrylate (-75 ° C), 3-methoxybutyl acrylate (-56 ° C), 2-ethoxy acrylate Methyl (the -50 ° C.), methacrylic acid n- octyl (the -25 ° C.), can be mentioned methacrylic acid n- decyl (the -49 ° C.).
These (meth) acrylic acid ester monomers (a1m) may be used alone or in combination of two or more.
These (meth) acrylic acid ester monomers (a1m) have a monomer unit (a1) derived from 80 to 99.9% by weight in the (meth) acrylic acid ester copolymer (A1), preferably Is used in the polymerization in an amount of 85 to 99% by weight, more preferably 90 to 97% by weight. If the usage-amount of a (meth) acrylic acid ester monomer (a1m) is less than the said range minimum, the pressure-sensitive adhesiveness in the vicinity of room temperature of the heat conductive pressure-sensitive-adhesive composition obtained from this will fall.

The monomer (a2m) that gives the monomer unit (a2) having an organic acid group is not particularly limited, and representative examples thereof include organic acid groups such as a carboxyl group, an acid anhydride group, and a sulfonic acid group. In addition to these, monomers containing sulfenic acid groups, sulfinic acid groups, phosphoric acid groups, and the like can also be used. Specific examples of the monomer having a carboxyl group include α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; α, β- such as itaconic acid, maleic acid, and fumaric acid. And ethylenically unsaturated polyvalent carboxylic acids; α, β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as methyl itaconate, butyl maleate and propyl fumarate; Moreover, what has group which can be induced | guided | derived to a carboxyl group by hydrolysis etc., such as maleic anhydride and itaconic anhydride, can be used similarly.
Specific examples of the monomer having a sulfonic acid group include allyl sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, α, β-unsaturated sulfonic acid such as acrylamide-2-methylpropane sulfonic acid, and the like. These salts can be mentioned.
Among these monomers having an organic acid group, monomers having a carboxyl group are preferred, and among these, acrylic acid and methacrylic acid are more preferred. These are industrially inexpensive and can be easily obtained, have good copolymerizability with other monomer components, and are preferable in terms of productivity.

These monomers (a2m) having an organic acid group may be used alone or in combination of two or more.
The monomer (a2m) having these organic acid groups has a monomer unit (a2) derived therefrom of 0.1 to 20% by weight in the (meth) acrylic acid ester copolymer (A1), preferably It is used for the polymerization in an amount of 1 to 15% by weight, more preferably 3 to 10% by weight. When the monomer (a2m) is used in an amount of less than 0.1% by weight, the resulting heat conductive pressure sensitive adhesive sheet is inferior in pressure sensitive adhesiveness.
The monomer unit (a2) having an organic acid group can be easily introduced into the copolymer by polymerization of the monomer (a2m) having an organic acid group, as described above. After forming the copolymer, an organic acid group may be introduced by a known polymer reaction.

The copolymer (A1) used for obtaining the (meth) acrylic acid ester copolymer (A) is a polymer unit derived from a monomer (a3m) containing a functional group other than an organic acid group ( a3) It may contain 10% by weight or less, preferably 5% by weight or less.
Examples of functional groups other than organic acid groups include hydroxyl groups, amino groups, amide groups, epoxy groups, mercapto groups, and the like.
Examples of the monomer having a hydroxyl group include (meth) acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.
Examples of the monomer containing an amino group include (meth) acrylic acid-N, N-dimethylaminomethyl, (meth) acrylic acid-N, N-dimethylaminoethyl, aminostyrene, and vinylpyridine. .
Examples of monomers having an amide group include α, β-ethylenically unsaturated carboxylic acid amide monomers such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, and N, N-dimethylacrylamide. Can be mentioned.
Examples of the monomer having an epoxy group include glycidyl (meth) acrylate and allyl glycidyl ether.
As the monomer (a3m) containing a functional group other than an organic acid group, one type may be used alone, or two or more types may be used in combination.
In the monomer (a3m) having a functional group other than these organic acid groups, the monomer unit (a3) derived therefrom is preferably 10% by weight or less in the (meth) acrylate copolymer (A1), preferably Is used in the polymerization in such an amount that it is 5% by weight or less. When the monomer (a3m) is used in an amount exceeding 10% by weight, the viscosity during polymerization is remarkably increased and solidified, making it difficult to handle the polymer.

The copolymer (A1) is composed of a unit (a1) derived from a (meth) acrylate monomer that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and a monomer unit having an organic acid group ( In addition to a monomer unit (a3) containing a functional group other than a2) and an organic acid group, a monomer unit (a4) derived from a monomer copolymerizable with these monomers (a4m) May be contained.
A monomer (a4m) may be used individually by 1 type, and may use 2 or more types together.
Although a monomer (a4m) is not specifically limited, As a specific example, (meth) acrylic acid ester monomers (a1m) other than (meth) acrylate monomer (a1m) that form a homopolymer having a glass transition temperature of −20 ° C. or lower are used. ) Acrylic acid ester monomer, α, β-ethylenically unsaturated polyvalent carboxylic acid complete ester, alkenyl aromatic monomer, conjugated diene monomer, non-conjugated diene monomer, vinyl cyanide monomer Carboxylic acid unsaturated alcohol ester, olefinic monomer and the like.
The amount of the monomer unit (a4) derived from the monomer (a4m) is an amount that is 10% by weight or less, preferably 5% by weight or less of the copolymer (A1).

Specific examples of the (meth) acrylate monomer other than the (meth) acrylate monomer (a1m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower include methyl acrylate (single The glass transition temperature of the polymer is 10 ° C., methyl methacrylate (105 ° C.), ethyl methacrylate (63 ° C.), n-propyl methacrylate (25 ° C.), and n-butyl methacrylate (20 ° C.). And the like.
Specific examples of the α, β-ethylenically unsaturated polycarboxylic acid complete ester include dimethyl fumarate, diethyl fumarate, di-n-butyl fumarate, dimethyl maleate, diethyl maleate, di-n-maleate. Examples thereof include butyl and dimethyl itaconate.
Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyl toluene and divinylbenzene.

Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro- Examples thereof include 1,3-butadiene and cyclopentadiene.
Specific examples of the non-conjugated diene monomer include 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene and the like.
Specific examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.
Specific examples of the carboxylic acid unsaturated alcohol ester monomer include vinyl acetate.
Specific examples of the olefin monomer include ethylene, propylene, butene, pentene and the like.

The weight average molecular weight (Mw) of the copolymer (A1) is preferably 200,000 or more as measured by gel permeation chromatography (GPC method), and may be in the range of 250,000 to 400,000. Is particularly preferred. When the weight average molecular weight (Mw) is within this range, the shape retainability is excellent.
The copolymer (A1) is a monomer other than the (meth) acrylic acid ester monomer (a1m), the monomer having an organic acid group (a2m), or an organic acid group, which forms a homopolymer having a temperature of −20 ° C. or lower. It can be obtained by copolymerizing a monomer (a3m) containing a functional group and a monomer (a4m) copolymerizable with these monomers used as necessary.
The polymerization method is not particularly limited, and may be any of solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, and the like, and may be other methods. Solution polymerization is preferred, and among these, solution polymerization using a carboxylic acid ester such as ethyl acetate or ethyl lactate or an aromatic solvent such as benzene, toluene or xylene as the polymerization solvent is preferred.
In the polymerization, the monomer may be added in portions to the polymerization reaction vessel, but it is preferable to add the whole amount at once.

The method for initiating the polymerization is not particularly limited, but it is preferable to use a thermal polymerization initiator as the polymerization initiator (B1). The thermal polymerization initiator is not particularly limited, and may be either a peroxide or an azo compound.
Examples of peroxide polymerization initiators include hydroperoxides such as t-butyl hydroperoxide; peroxides such as benzoyl peroxide and cyclohexanone peroxide; persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; Can do.
These peroxides can also be used as a redox catalyst in appropriate combination with a reducing agent.
As the azo compound polymerization initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile) Etc.
Although the usage-amount of a polymerization initiator (B1) is not specifically limited, Usually, it is the range of 0.01-50 weight part with respect to 100 weight part of monomers.
There are no particular restrictions on the other polymerization conditions (polymerization temperature, pressure, stirring conditions, etc.) of these monomers.

  After completion of the polymerization reaction, the obtained polymer is separated from the polymerization medium as necessary. The separation method is not particularly limited. In the case of solution polymerization, a polymer can be obtained by placing the polymerization solution under reduced pressure and distilling off the polymerization solvent.

  The (meth) acrylic acid ester copolymer (A) used in the present invention has a glass transition temperature of −20 ° C. or less in the presence of 100 parts by weight of the copolymer (A1) obtained as described above. (Meth) acrylic acid ester monomer (a5m) 70 to 99.9% by weight, monomer having organic acid group (a6m) 0.1 to 10% by weight, and Monomer mixture (A2m) 20-65 parts by weight of polymerizable monomer (a7m) 0-20% by weight, 0.05-20 parts by weight with respect to 100 parts by weight of monomer mixture (A2m) In the presence of 0.1 to 20 parts by weight of an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds.

As an example of the (meth) acrylic acid ester monomer (a5m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, (meth) acrylic acid ester used for the synthesis of the polymer (A1) The same (meth) acrylic acid ester monomer as the body (a1m) can be mentioned.
The (meth) acrylic acid ester monomer (a5m) may be used alone or in combination of two or more.
The ratio of the (meth) acrylic acid ester monomer (a5m) in the monomer mixture (A2m) is 70 to 99.9% by weight, preferably 80 to 99.5% by weight, more preferably 90 to 99% by weight. %.
When the ratio of the (meth) acrylic acid ester monomer (a5m) is less than the above range, the flexibility of the heat conductive pressure-sensitive adhesive composition obtained using the copolymer (A) becomes insufficient. . On the other hand, when more than the said range, it is inferior to the pressure sensitive adhesiveness of the heat conductive pressure sensitive adhesive composition obtained using a copolymer (A).

Examples of the monomer (a6m) having an organic acid group include the same monomers having an organic acid group as exemplified as the monomer (a2m) used for the synthesis of the polymer (A1). .
As the monomer having an organic acid group (a6m), one type may be used alone, or two or more types may be used in combination.
The ratio of the monomer (a6m) having an organic acid group in the monomer mixture (A2m) is 0.1 to 10% by weight, preferably 0.5 to 8% by weight, more preferably 1 to 5% by weight. It is.
When less than 0.1% by weight of monomer (a6m) is used, the resulting heat conductive pressure sensitive adhesive composition is inferior in pressure sensitive adhesiveness. On the other hand, when the monomer (a6m) is used in excess of 10% by weight, the heat conductive pressure-sensitive adhesive sheet is deformed by heat and pressure due to the weight of the roll-shaped scroll, and a phenomenon occurs that the shape cannot be maintained and hangs down.

(Meth) acrylic acid ester monomer (a5m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and a monomer copolymerizable with a monomer having an organic acid group (a6m) ( Examples of a7m) include the same monomers as exemplified as the monomer (a3m) or monomer (a4m) used for the synthesis of the polymer (A1).
The ratio of the monomer (a7m) in the monomer mixture (A2m) is an amount that is 20% by weight or less of the monomer mixture (A2m), preferably 12% by weight or less, more preferably 5% by weight or less. This is the amount.

  The amount of the monomer mixture (A2m) is 20 to 65 parts by weight, preferably 30 to 55 parts by weight, based on 100 parts by weight of the copolymer (A1). When the amount of the monomer mixture (A2m) is less than the lower limit of the above range, it is difficult to uniformly mix the (meth) acrylic acid ester copolymer (A) and the thermally conductive inorganic compound (D). The high temperature holding power and flexibility of the heat-conductive sheet-like molded product thus obtained are reduced. On the other hand, when the upper limit of the above range is exceeded, the polymerization reaction does not proceed sufficiently, the high temperature adhesive strength of the resulting thermally conductive sheet-like molded product is poor, and problems such as odor due to unreacted monomers occur.

In the present invention, when the monomer mixture (A2m) is polymerized in the presence of the copolymer (A1), it is essential to perform the polymerization in the presence of the thermal polymerization initiator (B2). If a photopolymerization initiator is used instead of a thermal polymerization initiator, the degree of polymerization may be uneven in the vicinity of the surface of the light-irradiated surface and in the interior of the sheet formed from the thermally conductive pressure-sensitive adhesive composition obtained. There is.
Examples of the thermal polymerization initiator (B2) include the same types of thermal polymerization initiators as those exemplified as the polymerization initiator (B1) used for the synthesis of the copolymer (A1). An initial temperature of 120 ° C. or higher and 170 ° C. or lower is preferable.
The usage-amount of a thermal-polymerization initiator (B2) is 0.05-20 weight part with respect to 100 weight part of monomer mixtures (A2m), Preferably it is 0.5-18 weight part, More preferably, it is 1-15. The range is parts by weight.
If the usage-amount of a thermal-polymerization initiator (B2) is less than 0.05 weight part, since the polymerizable monomer odor remains in the obtained heat conductive sheet, it is unpreferable. Moreover, the heat conductive pressure-sensitive adhesive sheet is deformed by heat and the pressure due to the weight of the roll-shaped scroll, and a phenomenon occurs that the shape cannot be maintained and hangs down. On the other hand, when the amount exceeds 20 parts by weight, the molecular weight of the resulting polymer is reduced, and as a result, the heat conductive pressure-sensitive adhesive sheet is deformed by heat and pressure due to the weight of the roll-shaped roll, and the shape cannot be retained and hangs down. Occurs.

The internal cross-linking agent (C2) having two or more polymerizable unsaturated bonds introduces intramolecular and / or intermolecular cross-links into the copolymer to increase the cohesive force as a pressure-sensitive adhesive, and to conduct heat-sensitive pressure. This is necessary to prevent the adhesive sheet from being deformed by heat and pressure due to its own weight.
Examples of the internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds include 1,6-hexanediol di (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, and 1,12-dodecane. Diol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Multifunctional (meth) acrylates such as erythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate ; And the like.

  The content of the internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds is 0.1 to 20 parts by weight, preferably 0.3 to 15 parts per 100 parts by weight of the monomer mixture (A2m). Part by weight, more preferably 0.5 to 10 parts by weight. When the content of the internal cross-linking agent (C2) having two or more polymerizable unsaturated bonds is less than 0.1 parts by weight, the heat conductive pressure-sensitive adhesive sheet is deformed due to heat and the pressure of the roll-shaped scroll, and the shape is The phenomenon of dripping without being held occurs. Moreover, when it exceeds 20 weight part, the hardness of a heat conductive pressure-sensitive-adhesive sheet becomes high and is unpreferable.

  The polymerization conversion rate of the monomer mixture (A2m) and the reaction rate of the internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds are preferably 95% by weight or more. If the polymerization conversion rate or the reaction rate is too low, the monomer odor remains in the obtained heat conductive sheet, which is not preferable. Moreover, the heat conductive pressure-sensitive adhesive sheet is deformed by heat and the pressure due to the weight of the roll-shaped scroll, and a phenomenon occurs that the shape cannot be maintained and hangs down.

The heat conductive pressure-sensitive adhesive composition of the present invention comprises a (meth) acrylic acid ester copolymer (A) and a heat conductive inorganic compound (D).
Examples of the thermally conductive inorganic compound (D) include metal oxides such as alumina, magnesium oxide, beryllium oxide and titanium oxide; metal nitrides such as boron nitride, silicon nitride and aluminum nitride; carbides such as silicon carbide; copper and silver Metals such as iron, aluminum and nickel; Carbon compounds such as diamond and carbon; Silica powder such as quartz and quartz glass, and the like. Preferably, the metal hydroxide of Group 2 or Group 13 of the Periodic Table is used. Oxide, oxide or nitride.
Examples of the Group 2 metal include magnesium, calcium, strontium, barium, and the like. Examples of the Group 13 metal include aluminum, gallium, and indium.
These heat conductive inorganic compounds (D) may be used individually by 1 type, and may use 2 or more types together.
The shape of the heat conductive inorganic compound (D) is not particularly limited, and may be any of a spherical shape, a needle shape, a fiber shape, a scale shape, a dendritic shape, a flat plate shape, and an indefinite shape.
Among the thermally conductive inorganic compounds (D), metal hydroxides are preferable, and aluminum hydroxide is particularly preferable. By using aluminum hydroxide, excellent flame retardancy can be imparted to the heat conductive pressure-sensitive adhesive composition of the present invention.

  As the aluminum hydroxide, one having a particle size of 0.2 to 120 μm, preferably 0.7 to 100 μm is usually used. Moreover, what has a particle size of 1-80 micrometers is more preferable. When the average particle size is less than 0.2 μm, the viscosity of the pressure-sensitive adhesive composition is increased, which may make it difficult to knead the polymer and the thermally conductive inorganic compound. There is a risk of reducing the adhesion of the shaped molded body. On the other hand, if it exceeds 120 μm, the holding power of the pressure-sensitive adhesive composition or the sheet-like molded product may be reduced.

In this invention, the usage-amount of a heat conductive inorganic compound (D) is 50-250 weight part with respect to 100 weight part of copolymers (A), Preferably it is 80-220 weight part, More preferably, it is 100-180 weight. Part range.
If the amount used is less than 50 parts by weight, there are problems such as high-temperature adhesive strength and thermal conductivity reduction. Conversely, if it exceeds 250 parts by weight, the hardness increases and the problem of poor adhesion occurs.

The heat conductive pressure-sensitive adhesive composition of the present invention contains the copolymer (A) and the heat conductive inorganic compound (D) in the above proportions, and, if necessary, pigments, other fillers, flame retardants, and aging. Various known additives such as an inhibitor, a thickener, and a tackifier can be contained.
The pigment can be used regardless of organic type or inorganic type such as carbon black and titanium dioxide.
Other fillers include inorganic compounds and organic compound fine particles. You may add nanoparticles, such as fullerene and a carbon nanotube.
Examples of the flame retardant include ammonium polyphosphate, zinc borate, tin compound, organic phosphorus compound, red phosphorus compound, and silicone flame retardant.
As an antioxidant, there is a high possibility of inhibiting radical polymerization, so that it is not usually used, but an antioxidant such as polyphenol, hydroquinone or hindered amine can be used as necessary.
As the thickener, inorganic polymer fine particles such as acrylic polymer particles and fine silica, and reactive inorganic compounds such as magnesium oxide can be used.
Examples of tackifiers include terpene resins, terpene phenol resins, rosin resins, petroleum resins, coumarone-indene resins, phenol resins, hydrogenated rosin esters, disproportionated rosin esters, xylene resins, and the like. it can.

Furthermore, in order to increase the cohesive force as a pressure-sensitive adhesive and improve heat resistance, etc., the heat conductive pressure-sensitive adhesive composition of the present invention is added with an external cross-linking agent, and the copolymer has a cross-linked structure. Can be introduced.
External crosslinking agents include polyfunctional isocyanate-based crosslinking agents such as trimethylene diisocyanate, trimethylolpropane diisocyanate, diphenylmethane triisocyanate; epoxy-based crosslinking agents such as diglycidyl ether, polyethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether Melamine resin crosslinking agent; amino resin crosslinking agent; metal salt crosslinking agent; metal chelate crosslinking agent; peroxide crosslinking agent;
The external cross-linking agent is used to form a cross-linkage within and / or between the molecules of the copolymer by obtaining a copolymer and then adding it to heat treatment or radiation irradiation treatment.

The method for obtaining the heat conductive pressure-sensitive adhesive composition of the present invention from the (meth) acrylic acid ester copolymer (A) and the heat conductive inorganic compound (D) is not particularly limited, and the heat conductive inorganic compound ( D) and a separately synthesized (meth) acrylic acid ester copolymer (A) may be used, but the (meth) acrylic acid ester copolymer (A) and the thermally conductive inorganic compound (D) From the viewpoint of uniformly mixing the (meth) acrylate copolymer (A), a method of simultaneously mixing the synthesis of the thermally conductive inorganic compound (D) is preferable.
When the method of mixing the thermally conductive inorganic compound (D) and the separately synthesized (meth) acrylic acid ester copolymer (A) is adopted, the mixing method is not particularly limited, and for example, dried ( Even in the dry mixing method in which the (meth) acrylic acid ester copolymer (A) and the thermally conductive inorganic compound (D) are mixed using a roll, a crusher, a kneader or the like, the organic solvent in the container equipped with a stirrer is used. A wet mixing method of mixing in the presence may also be used.
When the method of simultaneously synthesizing the (meth) acrylic acid ester copolymer (A) and mixing the (meth) acrylic acid ester copolymer (A) and the thermally conductive inorganic compound (D) is employed. Is a copolymer (A1), a monomer mixture (A2m), a thermal polymerization initiator (B2), an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and a thermally conductive inorganic compound (D It is preferred to heat under polymerization conditions after obtaining a mixture of At this time, the mixing order of each component is not particularly limited. Further, it is preferable to carry out the mixing at a temperature at which the polymerization of the monomer mixture (A2m) does not proceed.

The heat conductive pressure-sensitive adhesive composition of the present invention can be formed into a sheet-like molded body.
The sheet-like molded body may be composed of only a heat conductive pressure-sensitive adhesive composition, and is a composite composed of a base material and a heat conductive pressure-sensitive adhesive composition layer formed on one or both sides thereof. There may be.
Although the thickness of the heat conductive pressure-sensitive-adhesive composition layer in the sheet-like molded object of this invention is not specifically limited, Usually, they are 50 micrometers-3 mm. If it is thinner than 50 μm, air is likely to be involved when affixing to the heating element and the radiator, and as a result, sufficient thermal conductivity may not be obtained. On the other hand, if it is thicker than 3 mm, the thermal resistance of the sheet increases and the heat dissipation may be impaired.

When forming a heat conductive pressure sensitive adhesive composition layer in the single side | surface or both surfaces of a base material, a base material is not specifically limited.
Specific examples thereof include foils of metals and alloys having excellent thermal conductivity such as aluminum, copper, stainless steel, and beryllium copper; sheet-like materials made of a polymer having excellent thermal conductivity such as thermal conductive silicone; A heat conductive plastic film containing a heat conductive filler; various nonwoven fabrics; glass cloth; honeycomb structure; and the like can be used. Plastic films include polyimide, polyethylene terephthalate, polyethylene naphthalate, polytetrafluoroethylene, polyether ketone, polyethersulfone, polymethylpentene, polyetherimide, polysulfone, polyphenylene sulfide, polyamideimide, polyesterimide, aromatic polyamide, etc. A film made of a heat-resistant polymer can be used.

The method for producing a sheet-shaped molded article from the heat conductive pressure-sensitive adhesive composition is not particularly limited. For example, on a process paper such as a polyester film which has been subjected to release treatment of the heat conductive pressure-sensitive adhesive composition or a solution thereof. The solvent may be removed by an appropriate method if necessary. Further, the heat conductive pressure sensitive adhesive composition may be formed into a sheet by sandwiching between two exfoliated process papers if necessary and passing between rolls. Furthermore, when extruding from an extruder, it is possible to control the thickness through a die.
In addition, for example, by applying a heat conductive pressure-sensitive adhesive composition or a solution thereof on one or both sides of the substrate and removing the solvent if necessary, the substrate is heated by hot air, an electric heater, infrared rays, or the like. And a thermally conductive pressure-sensitive adhesive composition layer formed on one side or both sides thereof can be obtained.
Moreover, the heat conductive pressure-sensitive-adhesive composition of this invention can also be directly formed on base materials like a heat radiator, and can also be provided as a part of electronic component.

The thermally conductive sheet-like molded product of the present invention is a unit derived from a (meth) acrylic acid ester monomer (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower. The monomer unit (a2) having an organic acid group (0.1 to 20% by weight), the monomer unit (a3) containing a functional group other than the organic acid group (0 to 10% by weight), and copolymerizable therewith 100 parts by weight of the copolymer (A1) containing 0 to 10% by weight of the monomer unit (a4) derived from the monomer, and forming a homopolymer having a glass transition temperature of −20 ° C. or less (meta ) Acrylic acid ester monomer (a5m) 70-99.9% by weight, monomer having organic acid group (a6m) 0.1-10% by weight, and monomer copolymerizable therewith (a7m) Monomer mixture (A2m) consisting of 0 to 20% by weight, 20 to 65 parts by weight, monomer 0.05 to 20 parts by weight of a thermal polymerization initiator (B2), 0.1 to 20 parts by weight of an internal cross-linking agent having two or more polymerizable unsaturated bonds (100 parts by weight of the compound (A2m)) C2), and 50 to 250 parts by weight of the thermally conductive inorganic compound (D) are mixed, heated and formed into a sheet with respect to 100 parts by weight in total of the copolymer (A1) and the monomer mixture (A2m). Thus, it can be suitably obtained.
According to this method, simultaneously with the formation of the (meth) acrylic acid ester copolymer (A) from the copolymer (A1) and the monomer mixture (A2m), this is uniform with the thermally conductive inorganic compound (D). The sheet-like molded body of the heat conductive pressure-sensitive adhesive composition mixed in the above can be produced. According to the method of forming the heat conductive pressure sensitive adhesive composition in which the (meth) acrylic acid ester copolymer (A) is uniformly mixed with the heat conductive inorganic compound (D) at the same time, It is said that it has both the high-temperature adhesive force of the heat-conductive pressure-sensitive adhesive composition sheet-like molded body, which was difficult without photopolymerization and photocrosslinking, and pressure-sensitive adhesiveness over a wide temperature range from low temperature to high temperature. Performance can be achieved only by heat treatment. In addition, even in the heat history during transportation / storage, the performance of maintaining the shape without dripping the thermally conductive pressure-sensitive adhesive composition sheet-like molded article can be achieved.

  At this time, the copolymer (A1), the monomer mixture (A2m), the thermal polymerization initiator (B2), the internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and the thermally conductive inorganic compound ( After mixing D) under heating, the resulting mixture may be formed into a sheet (this method is referred to as “Production Method I”), but copolymer (A1), monomer mixture (A2m), thermal polymerization It is preferable to mix the initiator (B2), the internal cross-linking agent (C2) having two or more polymerizable unsaturated bonds, and the thermally conductive inorganic compound (D), and then form a sheet under heating (this method is referred to as “this method”). , "Production II").

In production method (I), copolymer (A1), monomer mixture (A2m), thermal polymerization initiator (B2), internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and thermal conduction Conductive Inorganic Compound (D) is mixed with heating, and then the resulting (meth) acrylic acid ester copolymer (A) and the thermally conductive inorganic compound (D) are uniformly mixed in a thermally conductive pressure-sensitive adhesive Sheet the composition.
The mixing method is not particularly limited, but the polymerization of the copolymer (A1) and the monomer mixture (A2m) is performed by a thermal polymerization initiator (B2) and an internal crosslinking agent having two or more polymerizable unsaturated bonds (C2 In order to ensure uniform mixing of the resulting (meth) acrylic acid ester copolymer (A) with the thermally conductive inorganic compound (D), use a powerful mixer. Is preferred. Mixing may be performed batchwise or continuously.
The order of mixing each component is not particularly limited.
Examples of the batch mixer include a high viscosity raw material kneader and a stirrer such as a crusher, a kneader, an internal mixer, and a planetary mixer. Examples of the continuous mixer include a Farrell type continuous kneader in which a rotor and a screw are combined, and a screw type kneader having a special structure. Moreover, the single screw extruder and the twin screw extruder currently used for the extrusion process are mentioned. Two or more of these extruders and kneaders may be combined, or a plurality of machines of the same type may be connected and used. Among these, a twin screw extruder is preferable from the viewpoint of continuity and shear rate.
The heating temperature needs to be a temperature at which the polymerization proceeds smoothly, and is usually in the range of 100 to 180 ° C, preferably 120 ° C to 160 ° C.
The atmosphere at the time of heating and mixing is not particularly limited as long as radical polymerization can proceed.
The method of making the heat conductive pressure-sensitive adhesive composition obtained by heating and mixing into a sheet is not particularly limited, but is a method of passing between rolls sandwiched between process papers, a method of passing a die when extruding from a kneader, etc. There is.

In production method (II), copolymer (A1), monomer mixture (A2m), thermal polymerization initiator (B2), internal cross-linking agent (C2) having two or more polymerizable unsaturated bonds, and thermal conduction After mixing the inorganic inorganic compound (D), it is formed into a sheet under heating.
Examples of the mixer for preparing the mixture include the same ones used in the production method (I).
The order of mixing each component is not particularly limited.
The temperature at the time of mixing each component shall be 60 degrees C or less. When mixing is performed at a temperature higher than 60 ° C., the monomer mixture (A2m) starts to be polymerized during mixing and the viscosity is increased, and the subsequent operation becomes difficult.
Next, the mixture of each component is formed into a sheet under heating. Upon heating, polymerization of the copolymer (A1) and the monomer mixture (A2m) proceeds in the presence of a thermal polymerization initiator (B2) and an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds. At the same time, by forming into a sheet, a thermally conductive sheet-like molded body is formed.
The heating temperature is in the range of 100 ° C to 180 ° C, preferably 120 ° C to 160 ° C. If the temperature is lower than 100 ° C., the polymerization reaction of the monomer mixture (A2m) does not proceed sufficiently, and the high-temperature holding power of the obtained sheet-like molded product may be reduced, causing problems such as generation of odor due to unreacted monomers. There is. If the temperature exceeds 180 ° C., the heat conductive sheet-like molded product may have poor appearance such as foaming.

Hereinafter, the present invention will be described in more detail with reference to examples. Parts and percentages in the examples are by weight unless otherwise specified.
In addition, the evaluation method of each characteristic of a (meth) acrylic acid ester copolymer, a heat conductive pressure-sensitive adhesive composition, and a heat conductive sheet is as follows.
(1) Weight average molecular weight (Mw) and number average molecular weight (Mn) of (meth) acrylic acid ester copolymer
It is determined in terms of standard polystyrene by gel permeation chromatography using tetrahydrofuran as a developing solvent.
(2) Hardness of thermally conductive sheet-like molded body Measured by the Japan Rubber Association Standard (SRIS) Asker C method.
(3) Thermal conductivity of thermally conductive sheet-like molded body It is measured at room temperature with a rapid thermal conductivity meter (QTM-500, manufactured by Kyoto Electronics Industry Co., Ltd.).

(4) Holding performance time (pressure-sensitive adhesiveness)
A test piece of 25 mm × 25 mm is stacked on an aluminum plate and pressed with a 2 kg roller, and then a glass plate is pressed on the other surface. After leaving for 1 hour, with this test piece in a vertical state, an aluminum plate is fixed to the wall, and a 500 g weight is suspended from the glass plate and placed in a constant temperature layer at 100 ° C. atmosphere. In this state, the time until the weight falls is measured.
(5) Shape-retaining property of thermally conductive sheet-like molded product In a thermostatic bath at 55 ° C., a roll-shaped scroll (thermal conductivity having a thickness of 1 mm, a width of 20 cm, and a length of 20 m temporarily attached to a polyethylene terephthalate film) A sheet-like molded body wound in a roll shape) is placed and left for 72 hours. After 72 hours, it is determined by the following whether or not the shape of the roll-shaped scroll is maintained.
○ The shape is maintained and there is no dripping.
△ A slight sag is observed in a part.
× It is a level that can be seen at a glance.

In a reactor, 100 parts by weight of a monomer mixture consisting of 94% by weight of 2-ethylhexyl acrylate and 6% by weight of acrylic acid, 0.03 parts by weight of 2,2′-azobisisobutyronitrile and 700% by weight of ethyl acetate A portion was added and dissolved uniformly. After purging with nitrogen, a polymerization reaction was carried out at 80 ° C. for 6 hours. The polymerization conversion rate was 97%. The obtained polymer was dried under reduced pressure to evaporate ethyl acetate to obtain a viscous solid copolymer (A1) (1). Copolymer (A1) (1) had Mw of 280,000 and Mw / Mn of 3.1.
In a mortar for a grinder, 100 parts by weight of the copolymer (A1) (1), 38.6% by weight of 2-ethylhexyl acrylate, 57.8% by weight of butyl acrylate, and 3.6% by weight of methacrylic acid Monomer mixture (A2m) (1) 38.9 parts by weight, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane (hereinafter abbreviated as “TMCH”) [1 minute The half-life temperature is 149 ° C. (B2) (1) 4.0 parts by weight, pentaerythritol triacrylate (hereinafter abbreviated as “PETA”) (C2) (1) 2.0 parts by weight, and aluminum hydroxide (D) (1) 210 The parts by weight were charged in a lump and thoroughly mixed at room temperature with a crusher. At this time, the weight ratios of TMCH (B2) (1) and PETA (C2) (1) to 100 parts by weight of the monomer mixture (A2m) (1) are 10.3 parts by weight and 5.1 parts by weight, respectively. . The weight ratio of aluminum hydroxide (D) (1) to the total 100 parts by weight of copolymer (A1) (1) and monomer mixture (A2m) (1) is 151 parts by weight. Thereafter, the mixture was defoamed with stirring under reduced pressure to obtain a viscous liquid sample. After a polyester film with a release agent was laid on the bottom of a mold having a length of 300 mm, a width of 200 mm, and a depth of 2 mm, the sample was poured into the mold and covered with a polyester film with a release agent. This was taken out from the mold and polymerized by pressing with a hydraulic press for 30 minutes under the conditions of 130 ° C. and 0.5 MPa, and heat conductive pressure sensitive adhesive covered with polyester film with release agent on both sides An agent composition sheet-like molded body (1) was obtained.
When the polymerization conversion rate of the monomer mixture (A2m) (1) was calculated from the amount of residual monomers in the sheet, it was 99.9%.
Each characteristic was evaluated about this heat conductive pressure sensitive adhesive composition sheet-like molded object (1). The results are shown in Table 1.

100 parts by weight of the same copolymer (A1) (1) (herein referred to as (A1) (2)) obtained in Example 1, 39.5% by weight of 2-ethylhexyl acrylate, butyl acrylate Monomer mixture (A2m) (2) 38.0 parts by weight consisting of 59.2% by weight and methacrylic acid 1.3% by weight, 4.0 parts by weight of TMCH (B2) (2), PETA (C2) ( 2) 1.0 part by weight and 190 parts by weight of aluminum hydroxide (D) (2) were added all at once and sufficiently mixed at room temperature using a crusher. At this time, the weight ratios of TMCH (B2) (2) and PETA (C2) (2) to 100 parts by weight of the monomer mixture (A2m) (2) are 10.5 parts by weight and 2.6 parts by weight, respectively. . The weight ratio of aluminum hydroxide (D) (2) to 138 parts by weight with respect to 100 parts by weight as a total of copolymer (A1) (2) and monomer mixture (A2m) (2). Then, operation similar to Example 1 was performed and the heat conductive pressure sensitive adhesive composition sheet-like molded object (2) by which both surfaces were covered with the polyester film with a mold release agent was obtained.
When the polymerization conversion rate of the monomer mixture (A2m) (2) was calculated from the amount of residual monomers in the sheet, it was 99.9%.
Each characteristic was evaluated about this heat conductive pressure sensitive adhesive composition sheet-like molded object (2). The results are shown in Table 1.

(Comparative Example 1)
Except not using PETA (C2), it carried out similarly to Example 1, and obtained the heat conductive pressure sensitive adhesive composition sheet (3) by which both surfaces were covered with the polyester film with a mold release agent. Each characteristic was evaluated about this heat conductive pressure sensitive adhesive composition sheet-like molded object (3). The results are shown in Table 1.

(Comparative Example 2)
100 parts by weight of the same copolymer (A1) (1) (herein referred to as (A1) (4)) obtained in Example 1, 35.3% by weight of 2-ethylhexyl acrylate, butyl acrylate 42.9 parts by weight of monomer mixture (A2m) (4) consisting of 52.9% by weight and 11.8% by weight of methacrylic acid, 4.0 parts by weight of TMCH (B2) (4), PETA (C2) ( 4) 2.0 parts by weight and 210 parts by weight of aluminum hydroxide (D) (4) were added all at once, and sufficiently mixed at room temperature using a crusher. At this time, the weight ratios of TMCH (B2) (4) and PETA (C2) (4) to 100 parts by weight of the monomer mixture (A2m) (4) are 9.4 parts by weight and 4.7 parts by weight, respectively. . Further, the weight ratio of aluminum hydroxide (D) (4) to 147 parts by weight with respect to 100 parts by weight in total of the copolymer (A1) (4) and the monomer mixture (A2m) (4). Then, operation similar to Example 1 was performed and the heat conductive pressure sensitive adhesive composition sheet-like molded object (4) by which both surfaces were covered with the polyester film with a mold release agent was obtained.
Each characteristic was evaluated about this heat conductive pressure-sensitive-adhesive composition sheet-like molded object (4). The results are shown in Table 1.

From the results in Table 1, the following can be understood.
A copolymer (A1), a monomer mixture (A2m), a thermal polymerization initiator (B2), an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and a thermally conductive inorganic compound (D); In Examples 1 and 2 in which a mixture was obtained by mixing, and the sheet-like molded body was prepared by carrying out sheeting simultaneously with the preparation of the heat-conductive pressure-sensitive adhesive composition under heating, the heat conductivity was excellent, and the hardness The heat conductive sheet-like molded object which was favorable, was high in adhesive force, and was excellent in the shape maintenance property of a roll-shaped roll was obtained.
On the other hand, in Comparative Example 1 in which pentaerythritol triacrylate (PETA), which is an internal cross-linking agent having two or more polymerizable unsaturated bonds, was not used, the shape of the roll-shaped roll of the thermally conductive sheet-shaped molded body was maintained. It became inferior.
Moreover, in the comparative example 2 with many amounts of methacrylic acid, hardness became high and it became inferior to the shape retainability of the roll-shaped roll of a heat conductive sheet-like molded object.

Claims (6)

(Meth) acrylic acid ester monomer-derived unit (a1) forming a homopolymer having a glass transition temperature of −20 ° C. or lower, 80 to 99.9% by weight, a monomer unit having an organic acid group (a2 ) 0.1 to 20% by weight, monomer unit containing a functional group other than organic acid group (a3) 0 to 10% by weight and a monomer unit derived from a monomer copolymerizable therewith (a4) (Meth) acrylic acid ester monomer that forms a homopolymer having a glass transition temperature of −20 ° C. or lower in the presence of 100 parts by weight of copolymer (A1) containing 0 to 10% by weight ( a5m) a monomer comprising 70-99.9% by weight, a monomer having an organic acid group (a6m) 0.1-10% by weight, and a monomer copolymerizable therewith (a7m) 0-20% by weight The monomer mixture (A2m) 100 to 20 to 65 parts by weight of the monomer mixture (A2m) In the presence of 0.05 to 20 parts by weight of thermal polymerization initiator (B2) and 0.1 to 20 parts by weight of an internal cross-linking agent (C2) having two or more polymerizable unsaturated bonds, based on parts by weight. A thermally conductive pressure-sensitive adhesive composition comprising 100 parts by weight of a (meth) acrylic acid ester copolymer (A) obtained by polymerizing to 50 parts by weight and 50 to 250 parts by weight of a thermally conductive inorganic compound (D). The heat conductive pressure-sensitive adhesive composition according to claim 1, wherein the heat conductive inorganic compound (D) is aluminum hydroxide. A thermally conductive sheet-like molded article comprising the thermally conductive pressure-sensitive adhesive composition according to claim 1 or 2. The heat conductive sheet-like molded object which consists of a base material and the heat conductive pressure-sensitive-adhesive composition layer of Claim 1 or 2 formed in the single side | surface or both surfaces. (Meth) acrylic acid ester monomer-derived unit (a1) forming a homopolymer having a glass transition temperature of −20 ° C. or lower, 80 to 99.9% by weight, a monomer unit having an organic acid group (a2 ) 0.1 to 20% by weight, monomer unit containing a functional group other than organic acid group (a3) 0 to 10% by weight and a monomer unit derived from a monomer copolymerizable therewith (a4) 100 parts by weight of copolymer (A1) containing 0 to 10% by weight, (meth) acrylic acid ester monomer (a5m) 70 to form a homopolymer having a glass transition temperature of −20 ° C. or lower Monomer mixture (99.9% by weight, monomer having organic acid group (a6m) 0.1 to 10% by weight, and monomer (a7m) copolymerizable therewith 0 to 20% by weight ( A2m) 20 to 65 parts by weight, monomer mixture (A2m) 100 parts by weight 0.05 to 20 parts by weight of a thermal polymerization initiator (B2), 0.1 to 20 parts by weight of an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and a copolymer (A1) Thermally conductive sheet-like molding characterized in that 50 to 250 parts by weight of the thermally conductive inorganic compound (D) is mixed, heated and formed into a sheet with respect to 100 parts by weight in total with the monomer mixture (A2m). Body manufacturing method. A copolymer (A1), a monomer mixture (A2m), a thermal polymerization initiator (B2), an internal crosslinking agent (C2) having two or more polymerizable unsaturated bonds, and a thermally conductive inorganic compound (D); 6. The method for producing a thermally conductive sheet-like molded body according to claim 5, wherein the sheet is formed by heating after mixing.