JP2008163126A - Resin composition for heat-release material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a heat-release material capable of attaining the heat-release material with suppressed odor and high strength even in the heat release material in which a large amount of thermal conductive filler is formulated. <P>SOLUTION: The resin composition for the heat-release material used for a material of the heat-release material contains a resin monomer having as a partial structure an α,β-unsaturated carbonyl group and an oxyalkylene group having an average addition molar number of 1-10 constituted by one kind or two kinds or more of oxyalkylene selected from oxyethylene, oxypropylene and oxybutyrene, or a polyoxyalkylene group and an alkoxyl group having a 4-12C saturated hydrocarbon group (provided that the carbon number is an average addition molar number or higher of the oxyalkylene group or the polyoxyalkylene group), and contains 35 mass% or more of a thermal conductive filler. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for a heat dissipation material used as a raw material for a heat dissipation material interposed between a heating element and a heat dissipation element, and in particular, a resin composition for a heat dissipation material for realizing a high-strength and low-odor heat dissipation material. It is about.

  A heat sink such as a heat sink, a heat radiating fin, or a metal heat radiating plate is provided on the surface of a heat generating body such as an electric / electronic component to increase the heat dissipation efficiency of the heat generating body. Further, a heat radiating material such as a heat conductive sheet for transferring heat from the heat generating body to the heat radiating body is generally provided between the heat generating body and the heat radiating body.

  The heat dissipation material is manufactured by polymerizing a resin monomer after blending a resin monomer, a polymerization initiator, and a heat conductive filler such as alumina or silica. In the heat radiating material manufactured in this way, in order to exert a heat conductive function, the heat conductive filler with respect to 100 parts by mass of the polymer resin may be set to 20 to 200 parts by mass (see, for example, Patent Document 1). . In order to realize a heat dissipating material that exhibits better thermal conductivity, the amount of the thermally conductive filler is increased (see, for example, Patent Document 2).

  By the way, the heat radiating material with a large amount of the thermally conductive filler is highly preferred by consumers because it has excellent thermal conductivity. However, when there are many blends of a heat conductive filler, the following problem will arise in relation to a polymerization initiator.

  When a photopolymerization initiator is selected as the polymerization initiator for polymerizing the resin monomer, a large amount of heat conductive filler blocks light, so that the polymerization of the resin monomer becomes insufficient. There is. On the other hand, it points out the problem when using the photopolymerization initiator, and it is disclosed that it is preferable to select a thermal polymerization initiator when using a large amount of thermally conductive filler (for example, (See Patent Document 3). However, even if a thermal polymerization initiator is selected, the heat for demonstrating the function of the thermal polymerization initiator is dissipated by a large amount of thermally conductive filler, so that the polymerization of the resin monomer becomes insufficient. Cannot be fundamentally solved.

The problem when the polymerization of the resin monomer becomes insufficient is accompanied by the problem that the heat dissipation material strength becomes insufficient. In addition, the resin monomer remains in the heat dissipation material that is insufficiently polymerized, and there may be a problem that the odor of this monomer is emitted from the heat dissipation material.
Japanese Patent No. 3636884 JP 2002-322449 A JP 2006-111644 A

  In view of the above circumstances, the present invention provides a heat dissipation material resin capable of realizing a high-strength heat dissipation material while suppressing odor even if the heat dissipation material contains a large amount of thermally conductive filler. The purpose is to provide a composition.

  The present inventor has intensively studied a resin monomer in a resin composition which is a raw material of the heat radiation material in order to increase the strength of the heat radiation material containing 35% by mass or more of the heat conductive filler. As a result, it has been found that if a resin composition containing a resin monomer having a predetermined partial structure is selected, a high-strength heat radiation material can be realized, and the present invention has been completed.

  That is, the present invention is a resin composition for a heat radiating material used as a raw material for a heat radiating material containing 35% by mass or more of a heat conductive filler, comprising an α, β-unsaturated carbonyl group, oxyethylene, and oxypropylene. And an oxyalkylene group or polyoxyalkylene group having an average addition mole number of 1 to 10 composed of one or more oxyalkylenes selected from oxybutylene, and a saturated hydrocarbon group having 4 to 12 carbon atoms A resin monomer having an alkoxy group having a partial structure as a partial structure, and the saturated hydrocarbon group has a larger number of carbon atoms than the average added mole number of the oxyalkylene group or polyoxyalkylene group. This is a resin composition for a heat dissipation material.

  According to the resin composition according to the present invention, it is possible to realize a heat dissipation material having high strength and suppressed odor despite containing a large amount of a heat conductive filler.

The resin composition for heat dissipation material of the present invention (hereinafter simply referred to as “resin composition”) contains a predetermined resin monomer as an essential component. In addition, a composition containing a polymerization initiator, a (meth) acrylic polymer, and a plasticizer necessary for the polymerization of the resin monomer also corresponds to the resin composition of the present invention. Furthermore, the resin composition of the present invention may contain additives such as an antioxidant.
Each component in the resin composition of this invention is explained in full detail below.

(Resin monomer)
The predetermined resin monomer in the resin composition of the present invention is composed of one or more monomers. The at least one monomer has an α, β-unsaturated carbonyl group and a group having a predetermined oxyalkylene group or polyoxyalkylene group and a predetermined alkoxy group as a partial structure (hereinafter referred to as “the predetermined A group having an oxyalkylene group or polyoxyalkylene group and a predetermined alkoxy group as a partial structure is referred to as an “X group”).

  The predetermined oxyalkylene group and polyoxyalkylene group in the X group are composed of one or more oxyalkylenes selected from oxyethylene, oxypropylene, and oxybutylene. Of these, oxyethylene is preferably selected.

  When the X group has a polyoxyalkylene group as a partial structure, the number of moles added of the oxyalkylene group is determined as the average number of moles added. This average number of moles is added to realize a low-odor and high-strength heat dissipation material, and to suppress the viscosity of the mixture of the heat conductive filler and the resin composition to a range in which the mixture is sufficiently and easily mixed. Is preferably 10 or less, more preferably 8 or less, and still more preferably 5 or less. And in order to manufacture the heat dissipation material of the especially outstanding intensity | strength, it is suitable that an average added mole number is 1.5-3.5. In addition, the average addition mole number of the oxyalkylene group in this invention is defined from the molecular weight distribution measured value by gel permeation chromatography (GPC).

  The predetermined alkoxy group in the X group is an alkoxy group having a linear, branched, or cyclic saturated hydrocarbon group. And the carbon number of the saturated hydrocarbon group is good in it being 4-12, Preferably it is 4-10, More preferably, it is 4-9. When the number of carbon atoms is less than 4, a low-odor and high-strength heat dissipation material cannot be produced. On the other hand, when the number of carbon atoms exceeds 12, crystallinity is likely to occur in the resin polymer in the heat dissipation material, making it difficult to produce a heat dissipation material with excellent flexibility.

  The structure of the predetermined alkoxy group is not particularly limited, such as linear, branched or cyclic. Examples of the alkoxy group include a linear alkoxy group such as n-butoxy group, pentoxy group, hexoxy group, heptoxy group, octoxy group, noninoxy group, decyloxy group, dodecyloxy group, nonylphenoxy group; sec-butoxy group Branched alkoxy groups such as tert-butoxy group and 2-ethylhexoxy group; cyclic alkoxy groups such as cyclobutoxy group, cyclopentoxy group, cyclohexoxy group, cycloheptoxy group, cyclooctoxy group, cyclonoroxy group and cyclodecyloxy group Group; Among these exemplified alkoxy groups, a 2-ethylhexoxy group is preferable because it is inexpensive and can increase the strength of the heat dissipation material.

  In the X group, the saturated hydrocarbon group has a carbon number (C number) larger than the average added mole number (n number) of the oxyalkylene group or polyoxyalkylene group. When the C number is not larger than the n number, a low odor and high strength heat dissipating material cannot be realized.

  X group may further have other partial structural groups such as —NH— group and —COO— group, as long as it has the above-mentioned predetermined oxyalkylene or polyoxyalkylene and the above-mentioned predetermined alkoxy group in the partial structure. .

  The resin monomer having an α, β-unsaturated carbonyl group and an X group as partial structures in the present invention is not particularly limited as long as it has these partial structures. As the structure of the resin monomer, a structure represented by the following formula (1) is preferable.

In the formula (1), the X group is the same as described above. In Formula (1), R ¹ is a hydrogen atom; an alkyl group such as a methyl group, an ethyl group, or a propyl group (preferably an alkyl group having 1 to 3 carbon atoms); or a methylol group (hydroxymethyl group); Represents an hydroxyalkyl group (preferably a hydroxyalkyl group having 1 to 2 carbon atoms) such as an ethylol group (hydroxyethyl group) or a butyrole group (hydroxybutyl group), and particularly preferred R ¹ is a hydrogen atom or a methyl group. .

  In the resin monomer represented by the above formula (1), a structure represented by the following formula (2) is particularly preferable.

In the above formula (2), R ¹ is the same as above. In the formula (2), — (OR ² ) n —OR ³ represents one type of X group, (OR ² ) n represents the predetermined oxyalkylene or polyoxyalkylene group that the X group has, and n is It represents that the average added mole number of oxyalkylene in (OR ² ) n is 1 to 10, and OR ³ represents the predetermined alkoxy group which the X group has. The carbon number of the saturated hydrocarbons in OR ³ is greater than (OR ²⁾ n number of ^n.

  The resin monomer having an α, β-unsaturated carbonyl group and an X group as partial structures in the present invention may have a structure represented by the following formula (3).

In formula (3), X is the same as described above. In formula (3), R ⁴ represents a hydroxyl group, an alkoxy group, or a hydroxyalkyl group. Here, examples of R ⁴ that is an alkoxy group include a methoxy group, an ethoxy group, an isopropyl group, an n-butoxy group, a t-butoxy group, and a 2-ethylhexoxy group (an alkoxy group having 1 to 8 carbon atoms). Is preferred). In addition, examples of R ⁴ that is a hydroxylalkyl group include a methylol group (hydroxymethyl group), an ethylol group (hydroxyethyl group), and a butyrole group (hydroxybutyl group) (hydroxy having 1 to 3 carbon atoms). An alkyl group is preferred).

  In the resin monomer represented by the above formula (3), a resin monomer having a structure represented by the following formula (4) is preferable.

In formula (4), R ⁴ is the same as above. In formula (4), —CHR ⁵ — (OR ² ) n —OR ³ represents a kind of X group. In the formula (4), R ⁵ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms (regardless of whether it is a linear or branched alkyl group, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group) And (OR ² ) n and OR ³ are the same as above. Here, the carbon number of the saturated hydrocarbon in OR ³ is a value larger than the n number of (OR ² ) n, as described above.

  As an example of the resin monomer in the present invention, if the compound represented by the above formula (2) is mentioned, diethylene glycol butyl ether (meth) acrylate, diethylene glycol hexyl ether (meth) acrylate, diethylene glycol (2-ethylhexyl) ether (meth) acrylate, Diethylene glycol dodecyl ether (meth) acrylate, tetraethylene glycol dodecyl ether (meth) acrylate, tetraethylene glycol nonyl phenyl ether (meth) acrylate, pentapropylene glycol nonyl phenyl ether (meth) acrylate, octaethylene glycol nonyl phenyl ether (meth) acrylate Decaethylene glycol dodecyl ether (meth) acrylate.

For example, the resin monomer represented by the above formula (2) in the present invention includes a compound having a general formula of HO— (OR ² ) n —OR ³ (for example, diethylene glycol mono (2-ethylhexyl) ether), (Meth) acrylic acid ester having the formula CH ₂ ═CR ¹ COOR (R ¹ is the same as above, R represents an optional substituent such as a hydrogen atom, a methyl group, etc.) in the presence of a catalyst It can be obtained by transesterification or dehydration condensation.

  As the resin monomer of the present invention, a resin monomer having a glass transition temperature of 0 ° C. or lower of a homopolymer obtained by polymerizing the monomer is preferably selected. When the glass transition temperature exceeds 0 ° C., the obtained heat dissipation material may not have sufficient flexibility. The glass transition temperature of the homopolymer of the resin monomer in the present invention is more preferably −25 ° C. or lower, and further preferably −40 ° C. or lower. In addition, a differential scanning calorimeter is used for the glass transition temperature, and a measured value under conditions of a temperature rising rate of 10 ° C./min is adopted. This measuring method is a measuring method for all glass transition temperatures in the present specification.

  The amount of the resin monomer in the resin composition is preferably 30 to 80% by mass, and 40 to 70% by mass when the total amount of the resin monomer, (meth) acrylic polymer and plasticizer is 100%. More preferably, it is more preferably 45 to 65% by mass. When the amount of the resin monomer is less than 30% by mass, the viscosity of the resin composition containing a large amount of the heat conductive filler increases, making it difficult to knead the resin composition. The problem is that the surface smoothness of the material and the heat conductivity of the heat dissipation material deteriorate. Moreover, if the amount of resin monomers is less than 30% by mass, the plasticizer may be easily separated from the heat dissipation material. On the other hand, if it exceeds 80% by mass, the resin and the thermally conductive filler may be separated during the preforming or molding into a sheet shape after kneading the thermally conductive filler and the resin composition.

(Polymerization initiator)
As the polymerization initiator, one or more radical polymerization initiators such as a thermal polymerization initiator and a photopolymerization initiator are selected.

  Examples of azo initiators that are thermal polymerization initiators include 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobis (2-methylpropionate), 2-phenylazo-2, 4-dimethyl-4-methoxyvaleronitrile.

  Examples of organic peroxides that are thermal polymerization initiators include ketone peroxides such as methyl ethyl ketone peroxide; hydroperoxides such as cumene hydroperoxide; diacyl peroxides such as benzoyl peroxide and dilauryl peroxide. Oxides; dialkyl peroxides such as dicumyl peroxide; peroxyketals such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane; t-amylperoxy-2-ethyl Hexanate, t-butyl peroxy-2-ethyl hexanate, t-amyl peroxy-3,5,5-trimethyl hexanate, 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanate , T-butylperoxy-3,5,5-trimethylhexanate, t- Alkyl peresters such as butyl peroxypivalate; t-butyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexyl carbonate, 1,6-bis (t-butylperoxycarbonyloxy) hexane, bis ( 4-tert-butylcyclohexyl) peroxydicarbonate and other percarbonates.

  When a thermal polymerization initiator is used, it is preferable to select a thermal polymerization initiator having a 10-hour half-life of 35 to 100 ° C, more preferably 40 to 90 ° C, still more preferably 40 to 75 ° C. It is a thermal polymerization initiator with a 10-hour half-life. This preferable polymerization initiator is, for example, bis (4-t-butylcyclohexyl) peroxydicarbonate and diacyl peroxide.

  Examples of the photopolymerization initiator include benzoin alkyl ethers such as benzoin methyl ether and benzoin ethyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 4- (1-t- Acetophenones such as butyldioxy-1-methylethyl) acetophenone; anthraquinones such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone; 2,4-dimethylthioxanthone, 2,4- Thioxanthones such as diisopropylthioxanthone and 2-chlorothioxanthone; Ketals such as acetophenone dimethyl ketal and benzyldimethyl ketal; Benzophenone and 4- (1-t-butyldioxy-1-methylethyl) benzo Benzophenones such as enone, 3,3 ′, 4,4′-tetrakis (t-butyldioxycarbonyl) benzophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1- ON, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; acylphosphine oxides and xanthones.

  The amount of the polymerization initiator used is not particularly limited as long as the resin monomer can be radically polymerized at a predetermined polymerization rate, and can be appropriately set according to the type of the radical polymerization initiator. The amount of use is, for example, preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the resin monomer, preferably 0.5 to 3 parts by mass, and more preferably 0.8 to 2 parts by mass. In addition, the radical polymerization initiator may be added in portions as necessary, or may be added after being diluted with a plasticizer. When diluting with a plasticizer, the necessary amount of dilution is used from a predetermined amount of liquid plasticizer.

((Meth) acrylic polymer)
As the (meth) acrylic polymer blended as the composition of the resin composition of the present invention, a known (meth) acrylic polymer used as a resin composition can be used. It is preferable to use a (meth) acrylic polymer having a hydroxyl value equal to or greater than a predetermined value.

  The (meth) acrylic polymer in the resin composition includes not only a single monomer polymer but also a polymer of two or more monomers. The (meth) acrylic polymer is meant to include a binary or ternary multi-component copolymer.

  When the glass transition temperature of the (meth) acrylic polymer is high, the heat dissipation material may not be sufficiently flexible. Therefore, it is preferable to select a (meth) acrylic polymer having a glass transition temperature of 0 ° C. or lower. The glass transition temperature is more preferably −30 ° C. or lower, and further preferably −40 ° C. or lower.

  The weight average molecular weight (Mw) of the (meth) acrylic polymer is preferably in the range of 10,000 to 1,000,000, more preferably in the range of 30,000 to 800,000, and in the range of 50,000 to 500,000. Most preferred. It is not preferable that Mw is less than 10,000 because the obtained heat-dissipating material has low performance such as solvent resistance and heat resistance. On the other hand, if Mw exceeds 1 million, the viscosity of the (meth) acrylic polymer itself becomes too high, and the purpose of highly blending the thermally conductive filler may not be achieved. In addition, the measurement result of the gel permeation chromatography (GPC) using polystyrene as a standard substance and tetrahydrofuran as an eluent is employ | adopted for said Mw.

  The (meth) acrylic polymer preferably has a hydroxyl value of 5 mg / KOH or more, more preferably 8 mgKOH / g or more, and still more preferably 18 mgKOH / g or more. The larger the hydroxyl value of the (meth) acrylic polymer, the lower the viscosity of the mixture of the heat conductive filler and the resin composition, and the easier the kneading work for preparing the mixture. As a result, it is possible to increase the blending amount of the heat conductive filler for obtaining a heat conductive material having high heat conductivity. Moreover, the greater the hydroxyl value of the (meth) acrylic polymer, the higher the strength of the heat dissipation material.

  However, if the hydroxyl value of the (meth) acrylic polymer exceeds 90 mgKOH / g, the viscosity at the time of polymerization of the polymer becomes very high, so that stable polymerization becomes difficult and a hydrophobic resin monomer is mixed. Sometimes phase separation is likely to occur. Therefore, the upper limit of the hydroxyl value of the (meth) acrylic polymer is preferably 90 mgKOH / g, more preferably 85 mgKOH / g, and still more preferably 80 mgKOH / g.

  The hydroxyl value of the (meth) acrylic polymer is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group when 1 g of (meth) acrylic polymer is acetylated. . This hydroxyl value is a value calculated by a method based on the neutralization titration method in JIS K0070.

  In order to increase the hydroxyl value of the (meth) acrylic polymer to 5 mgKOH / g or more, a radical polymerizable monomer having a hydroxyl group (hereinafter referred to as “first raw material monomer”) is used as the raw material for the (meth) acrylic polymer. Good. Further, as the amount of the first raw material monomer used is larger, the value of the hydroxyl value can be increased. As long as a desired hydroxyl value can be obtained, a radical polymerizable monomer having no hydroxyl group (in the following, "Second raw material monomer") is used in combination with the first raw material monomer.

  One or two or more monomers are used as the first raw material monomer. Examples of the first raw material monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono ( Mention may be made of (meth) acrylic monomers such as (meth) acrylate and glycerin (meth) acrylate. In addition, since radically polymerizable monomers such as hydroxystyrene also have a hydroxyl group, they correspond to the first raw material monomer.

  On the other hand, as the second raw material monomer, one or more of (meth) acrylic monomers having no hydroxyl group may be used. In addition, a radically polymerizable monomer having no hydroxyl group such as styrene or vinyl acetate can be used as the second raw material monomer.

  When a (meth) acrylic monomer is used as the second raw material monomer, it is preferable to use (meth) acrylic acid alkyl ester. The alkyl group in this (meth) acrylic acid alkyl ester is not limited to a straight chain, but is a branched chain having a lower alkyl group (for example, an alkyl group having about 1 to 3 carbon atoms) in the side chain. There may be. Examples of alkyl (meth) acrylate esters include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, nonyl ( They are (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, stearyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. In particular, it is preferable to use 2-ethylhexyl (meth) acrylate because a heat-dissipating material having high strength can be produced.

  When the above (meth) acrylic acid alkyl ester is used as the second raw material monomer, in order to obtain a highly flexible heat radiating material, the alkyl group portion has 2 to 18 carbon atoms (more preferably 3 to 15 carbon atoms). It is preferred to use a meth) acrylic acid alkyl ester.

  The amount of the (meth) acrylic acid alkyl ester in the second raw material monomer is preferably 50% by weight or more, more preferably 70% by weight or more when the total amount of the second raw material monomer is 100% by weight. 80% by mass or more is more preferable. By using 50% by mass or more of the (meth) acrylic monomer having no hydroxyl group as described above, it is possible to realize a highly flexible heat dissipating material and to suppress bleed out of the plasticizer.

  The amount of the (meth) acrylic polymer in the resin composition is preferably 10 to 50% by mass, more preferably 100% when the total amount of the resin monomer, (meth) acrylic polymer and plasticizer is 100%. Is 15 to 40% by mass, more preferably 15 to 35% by mass. If the amount of the (meth) acrylic polymer is less than 10% by mass, the resin monomer and other resin composition components tend to be separated when polymerizing the resin monomer, and if it exceeds 50% by mass, the resin composition A thing becomes high viscosity and there exists a tendency for workability | operativity and the surface smoothness of a thermal radiation material to deteriorate.

  The (meth) acrylic polymer can be obtained by a known radical polymerization method such as bulk polymerization, solution polymerization, or emulsion polymerization. In the production of the (meth) acrylic polymer, a chain transfer agent, an antioxidant or the like is used according to the characteristics of the heat dissipation material.

(Plasticizer)
In order to ensure the flexibility of the heat dissipation material, one or more plasticizers may be included in the resin composition according to the present invention. In order to stably develop the long-term flexibility of the heat dissipation material, it is preferable to use a plasticizer with high heat resistance. The “plasticizer with high heat resistance” as used herein means a weight loss rate when placed in a 130 ° C. temperature atmosphere for 24 hours [= 100 × (mass before placing in a 130 ° C. temperature atmosphere−130 ° C. temperature atmosphere) The weight of the plasticizer after being placed in a temperature atmosphere at 130 ° C.] is 2% by mass or less. When particularly high heat resistance is required, the weight loss rate when placed in a 150 ° C. temperature atmosphere for 100 hours [= 100 × (mass before placing in a 150 ° C. temperature atmosphere−after placing in a 150 ° C. temperature atmosphere) It is preferable to select a plasticizer with a mass of 1 mass% / mass before being placed in a 150 ° C. temperature atmosphere] of 1% by mass or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The weight loss rate is the measured value before and after placing the plasticizer in a hot air dryer adjusted to a predetermined temperature by accurately weighing about 3 g of the plasticizer in a metal watch glass with a diameter of 5 cm. adopt.

When selecting a plasticizer excellent in heat resistance, most of them are selected from liquid plasticizers having an aromatic ring (particularly a benzene ring). For example, phthalates such as didecyl phthalate, diundecyl phthalate, didodecyl phthalate, etc., preferably di-C _8-15 alkyl esters of phthalate (preferably di-C _9-13 alkyl esters of phthalates, di-C _10-12 alkyl esters of phthalates) Acid ester; trimellitic acid tri-C such as trioctyl trimellitic acid, trinonyl trimellitic acid, triisononyl trimellitic acid, tridecyl trimellitic acid, triisodecyl trimellitic trimellitic acid, trimellitic acid tri-2-ethylhexyl trimellitate _Trimellitic acid esters such as _7-14 alkyl esters (preferably trimellitic acid tri C _8-12 alkyl esters); pyromellitic acid tetra C _6-13 alkyl esters such as pyromellitic acid _tetraoctyl (preferably _{tetramellitic} pyromellitic acid tetra C _7-10 alkyl esters) peak, such as Trimellitate esters; cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate C _1-3 alkyl group on the benzene ring of the phosphate or the like is selected from phosphoric acid esters, such as good triphenyl phosphate be substituted. Among the above examples, trimellitic acid ester type and pyromellitic acid ester type are preferable, and pyromellitic acid ester plasticizer is most preferable.

Bleeding out of the plasticizer may occur on the surface of the heat dissipating material. In order to remarkably suppress this bleeding out, dipentaerythritol fatty acid ester, pentaerythritol, which is an esterified product of dipentaerythritol and fatty acid, often using erythritol fatty acid ester plasticizers pentaerythritol fatty acid esters are esters of fatty acids, using dipentaerythritol C ₈ fatty acid esters are esters of fatty acids of dipentaerythritol and carbon number 8 It is preferable.

Further, when a pentaerythritol fatty acid ester plasticizer is selected as the plasticizer, the larger the difference between the average added mole number of the oxyalkylene group in the X group and the carbon number of the saturated hydrocarbon in the alkoxy group of the X group ( The difference is preferably 2 or more, more preferably 3 or more, still more preferably 5 or more), and an increase in the hardness of the heat dissipation material can be suppressed (durability of the heat dissipation material is improved). As the pentaerythritol fatty acid ester plasticizer for suppressing the increase in hardness of the heat dissipating material, dipentaerythritol C ₈ fatty acid esters are preferred.

  The amount of the plasticizer in the resin composition is preferably 10 to 40% by mass, preferably 15 to 35% by mass, when the total amount of the resin monomer, (meth) acrylic polymer and plasticizer is 100%. More preferably, it is more preferably 20 to 30% by mass. If the amount of the plasticizer is less than 10% by mass, it is difficult to obtain a heat dissipation material having practical flexibility, and if it exceeds 40% by mass, the plasticizer may be separated from the heat dissipation material.

(Additive)
The resin composition of the present invention may contain an additive in order to realize a heat dissipation material having excellent characteristics. Additives include polyfunctional monomers, antioxidants, chain transfer agents, and the like. The additives listed in this example will be described below.

(Multifunctional monomer)
The “polyfunctional monomer” in the present invention means a monomer having two or more radical polymerizable double bonds in one molecule. If it is a polyfunctional monomer, these 1 type (s) or 2 or more types can be used. When a polyfunctional monomer is used, it becomes possible to improve the heat resistance, chemical resistance, and creep properties of the heat dissipation material, so the polyfunctional monomer can be added to the resin composition according to the characteristics required for the heat dissipation material. It is good to add.

Examples of the polyfunctional monomer include polyfunctional (meth) acrylic monomers, divinylbenzene, diallyl phthalate, triallyl cyanurate, and the like. Of these, polyfunctional (meth) acrylic monomers are exemplified by (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, Di (meth) acrylates such as neopentylglycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate (preferably C _2-8 alkanediol di (meth) acrylate); trimethylolpropane tri (meth) Tri (meth) acrylate such as acrylate; Tetra (meth) acrylate such as pentaerythritol tetra (meth) acrylate; Condensation of the di, tri and / or tetra (meth) acrylates such as dipentaerythritol hexa (meth) acrylate Things.

  When the polyfunctional monomer is added to the resin composition, the addition amount is preferably 2 parts by mass or less, preferably 1 part by mass or less with respect to 100 parts by mass of the total amount of the resin monomer and the (meth) acrylic polymer. Is more preferable, and 0.5 mass part or less is still more preferable. When a polyfunctional monomer exceeds 2 mass parts, the flexibility of the obtained heat radiating material may fall.

(Antioxidant)
Antioxidants (including UV absorbers and UV stabilizers) are suitable additives when it is necessary to maintain the long-term flexibility of the heat dissipation material. The larger the molecular weight of the antioxidant, the higher the effect of suppressing the increase in the hardness of the heat dissipation material. Therefore, it is preferable to select an antioxidant having a molecular weight of 200 or more, more preferably 300 or more, and even more preferably 1000 or more.

  Examples of the antioxidant include 2,6-di-t-butyl-p-cresol (BHT), butylated hydroxyanisole (BHA), 2,6-di-t-butyl-4-ethylphenol, stearyl- monophenolic antioxidants such as β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2 ′ -Methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [ 5,5] Bisphenol antioxidants such as can; 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris ( 3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, bis [3, 3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl ) -S-triazine-2,4,6- (1H, 3H, 5H) trione, polymer phenolic antioxidants such as tocopherols.

  Further, as an antioxidant, dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditridecyl-3,3 ′ Sulfur-based antioxidants such as thiodipropionate and pentaerythritol tetrakis (3-laurylthiopropionate) can also be used.

  Further, as an antioxidant, triphenyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-ditridecyl) phosphite, cyclic neopentanetetrayl bis ( Octadecyl phosphite), tris (nonylphenyl) phosphite, tris (mono and / or dinonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene, 10 -Decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t -Butylphenyl) phosphite, cyclic neopen Phosphorous antioxidants such as N-tetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite and 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite It can be used.

  Other antioxidants include N-phenyl-β-naphthylamine, N, N′-diphenyl-p-phenylenediamine, N, N′-di-β-naphthyl-p-phenylenediamine, and N-phenyl-N′-. Polymers of isopropyl-p-phenylenediamine, 2-mercaptobenzimidazole, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline, etc. Amine antioxidants can also be used.

  Among the above antioxidants, phenolic (particularly polymeric phenolic), sulfur, and phosphorus are preferable, and a combined system of polymeric phenolic and sulfur is particularly preferable.

  Examples of the UV absorber and UV stabilizer that can be used as an antioxidant include salicylic acid-based UV absorbers such as phenyl salicylate and pt-butylphenyl salicylate; 2-hydroxy-4-methoxybenzophenone, Benzophenone ultraviolet absorbers such as 2-hydroxy-4-octoxybenzophenone and 2,2′-dihydroxy-4-methoxybenzophenone; benzotriazole ultraviolet rays such as 2 ′-(2-hydroxy-5-methylphenyl) benzotriazole Absorbers; Cyanoacrylate ultraviolet absorbers such as 2-ethylhexyl-2-cyano-3,3′-diphenyl acrylate; Hindered amine ultraviolet stabilizers.

  The addition amount of the antioxidant with respect to the resin composition may be 0.01 to 3 parts by mass, preferably 0.03 to 1 part by mass, and more preferably 0.05 to 0 with respect to 100 parts by mass of the resin monomer. .5 parts by mass.

(Chain transfer agent)
Examples of the chain transfer agent added to the resin composition include α-methylstyrene dimer, carbon tetrachloride, and thiol compounds (eg, n-dodecyl mercaptan). The amount of chain transfer agent added to the resin composition is appropriately set.

  The composition of the resin composition of the present invention is as described above. When the resin composition of the present invention contains (meth) acrylic polymer, resin monomer and plasticizer as components, (1) when (meth) acrylic polymer is produced by solution polymerization method or emulsion polymerization method, After completion of evaporation, water and solvent are volatilized and then a (meth) acrylic polymer, a resin monomer and a plasticizer are mixed to produce a resin composition. (2) (meth) acrylic polymer is obtained by a bulk polymerization method. In the case of production, it is preferable to produce a resin composition by mixing (meth) acrylic polymer, resin monomer and plasticizer after completion of the bulk polymerization. If a method of polymerizing a (meth) acrylic polymer in the presence of a plasticizer is employed, a mixture of a (meth) acrylic polymer and a plasticizer can be obtained in one step. Of course, a plasticizer may be further added to the mixture produced in this one step.

Next, the manufacturing method of the heat dissipation material which used the resin composition of this invention as the raw material is demonstrated.
The heat dissipation material using the resin composition is obtained by polymerizing the resin monomer in the resin composition after kneading the resin composition and the heat conductive filler in the same manner as a known heat dissipation material.

  As the heat conductive filler used as the material of the heat dissipation material, one type or two or more types of heat conductive fillers can be used. Examples of the thermally conductive filler include inorganic oxide fillers such as aluminum oxide, magnesium oxide, zinc oxide, and silicon oxide; inorganic hydroxide fillers such as aluminum hydroxide and magnesium hydroxide; carbide fillers such as silicon carbide; Nitride fillers such as aluminum, boron nitride, and silicon nitride; metal fillers such as silver, copper, aluminum, iron, zinc, nickel, tin, and alloys thereof (for example, copper-tin alloys); carbon such as carbon and graphite Quality fillers; and the like. The inorganic hydroxide not only functions as a heat conductive filler that improves the heat conduction of the heat dissipation material, but also functions as a flame retardant. Therefore, it is preferable to select an inorganic hydroxide according to the use required for the heat dissipation material.

  The shape of the heat conductive filler is not particularly limited, such as a spherical shape, a fiber shape, a scale shape, a flat shape, a crushed shape, an indefinite shape, and the like. Moreover, although the magnitude | size of a heat conductive filler is not specifically limited, For example, an average particle diameter is good in it being about 1-100 micrometers. If it is necessary to measure the thermal conductivity of the thermally conductive filler, the sintered product can be measured by the hot disk method. In this measurement, for example, a thermal conductivity measuring device manufactured by Kyoto Electronics Industry Co., Ltd. (Part number TPA-501) may be used.

  Depending on the purpose of highly dispersing the thermally conductive filler in the resin composition and the purpose of improving the amount of thermally conductive filler in the resin composition, the thermal conductivity surface-treated by silane treatment etc. A filler may be used.

  The usage-amount of a heat conductive filler should just be the quantity used as 35 mass% or more in a thermal radiation material. Preferably it is 60 mass% or more, More preferably, it is 80 mass% or less. This is because the higher the content of the heat conductive filler in the heat radiating material, the more general the tendency of the heat radiating effect of the heat radiating material to improve. In order to realize a practical heat dissipation material, an amount that makes the heat conductivity of the heat dissipation material 1 W / m · K or more is used. However, when the usage-amount of a heat conductive filler increases too much, the mixture of a resin composition and a heat conductive filler will become high viscosity too much, and the manufacturing efficiency of a heat radiating material will fall. Further, although depending on the characteristics required for the heat dissipation material, the flexibility of the heat dissipation material may be insufficient. Therefore, the upper limit of the heat conductive filler usage is preferably 95% by mass.

  In order to knead the resin composition and the thermally conductive filler, a kneader such as a mixer, a roll mill, a Banbury mixer, a kneader, a pressure type kneader, or a biaxial kneader may be used. This kneading may be performed under reduced pressure or may be performed while heating or pressurizing in order to realize a heat radiating material with a small amount of remaining bubbles and high thermal conductivity.

  In the period from when the resin monomer of the resin composition is polymerized to obtain the heat dissipation material, the kneaded product of the resin composition and the heat conductive filler can be formed into a desired shape. The molding shape and molding method are not particularly limited. The molded shape is preferably a versatile sheet, and the sheet thickness is preferably 0.5 mm or more, which is frequently used as a heat dissipation material. In addition, as a molding method, for example, there are a method of forming into a desired shape using an injection mold or a batch mold, and a method of forming into a desired shape using an extruder or a casting mold.

  You may perform the said shaping | molding before starting the superposition | polymerization of the resin monomer in a kneaded material. It is also possible to mold the kneaded material in parallel while the polymerization of the resin monomers in the kneaded material proceeds. In this case, molding is performed while heating the kneaded material containing the thermal polymerization initiator. In order to perform molding and polymerization in parallel, the temperature range for heating the kneaded product is preferably 10 to 70 ° C. higher than the 10-hour half-life temperature of the thermal polymerization initiator, more preferably The range is 20 to 70 ° C. higher than the 10-hour half-life temperature of the polymerization initiator, and more preferably 30 to 70 ° C. higher than the 10-hour half-life temperature of the polymerization initiator.

  Polymerization of the resin monomer proceeds by heating when the kneaded product contains a thermal polymerization initiator, and when the kneaded product contains a photopolymerization initiator, the kneaded product is irradiated with light. It progresses by. Among them, the method of polymerizing a resin monomer with a thermal polymerization initiator is preferable because the curing device used is simple and low cost.

  When the resin monomer is polymerized using a thermal polymerization initiator, a known curing accelerator or curing accelerator may be used in order to accelerate the action of the thermal polymerization initiator. On the other hand, when a resin monomer is polymerized using a photopolymerization initiator, a known sensitizer or the like may be used.

  As described above, it is possible to produce a heat dissipation material using the resin composition of the present invention. In addition, in the manufacturing process of a thermal radiation material, materials other than the said resin composition and a heat conductive filler may be used for a raw material. For example, reinforcing fiber, inorganic / organic filler, polymerization inhibitor, low shrinkage agent, mold release agent, thickener, defoaming agent, wetting agent, dispersant, thixotropic agent, flame retardant, coupling agent Pigments, dyes, magnetic substances, antistatic agents, electromagnetic wave absorbers, pasty oils, paraffin wax, microcrystalline wax, higher fatty oils, thermal softeners, and the like.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention. In Examples and Comparative Examples, “parts” means “parts by mass” and “%” means “mass%” unless otherwise specified.

  The preparation methods of acrylic resins A to C (mixtures of acrylic polymer and plasticizer) used in Examples and Comparative Examples and methods for measuring physical properties are as follows.

(Acrylic resin A)
In a container equipped with a thermometer, a stirrer, a gas introduction tube, a reflux condenser, and a dropping funnel, 38.4 parts of 2-ethylhexyl acrylate (hereinafter referred to as “2EHA”) as the second raw material monomer, and the first raw material monomer 1.6 parts of 2-hydroxyethyl acrylate (hereinafter referred to as “HEA”) and dipentaerythritol C ₈ fatty acid ester (Adeka Sizer UL-6, manufactured by Asahi Denka Kogyo Co., Ltd.); Viscosity = 145 mPa · s; mass loss rate at 130 ° C. in 24 hours = 0.10%) 55 parts, chain transfer agent α-methylstyrene dimer 0.09 part was charged, and the inside of the container was replaced with nitrogen gas . The oxygen concentration in the gas phase portion in the container was measured with an oxygen concentration meter (“UC-12” manufactured by Central Science Co., Ltd.) and found to be 0.0%.

Next, the internal temperature of the container was raised to 75 ° C., 5 parts of the dipentaerythritol C ₈ fatty acid ester and dimethyl-2,2′-azobis (2-methylpropionate) 0. The mixed solution with 1 part was charged into a dropping funnel and dropped into the container over 2 hours. Thereafter, the reaction was continued at 75 ° C. for 1.5 hours, 0.02 part of dimethyl-2,2′-azobis (2-methylpropionate) was added, the temperature was raised to 90 ° C., and polymerization was performed for 2 hours. It was. Before completion of the polymerization, air was blown into the container to cool the reaction system, and the polymerization was terminated to obtain an acrylic resin A in which the (meth) acrylic polymer A and the plasticizer were mixed.

  The viscosity of the acrylic resin A, the residual amount of 2EHA, the weight average molecular weight Mw, the number average molecular weight Mn, the glass transition temperature Tg, and the hydroxyl value of the acrylic polymer in the resin A were measured. As for the viscosity, the viscosity at 25 ° C. was measured using a B type viscometer (“RB80L” manufactured by Toki Sangyo Co., Ltd.). 4, measured at 30 rpm, the residual amount of 2EHA was measured by gas chromatography, the weight average molecular weight Mw and the number average molecular weight Mn were measured by gel permeation chromatography, and the glass transition temperature Tg Was measured with a differential scanning calorimeter, and the hydroxyl value was measured according to the neutralization titration method in JIS K0070.

(Acrylic resin B)
As a plasticizer, pyromellitic acid ester ("Adekasizer UL-100" manufactured by Asahi Denka Kogyo Co., Ltd .; viscosity at 25 ° C = 176 mPa · s; mass loss rate in an atmosphere of 130 ° C and 130 ° C for 24 hours = 0.09%) The acrylic resin B was obtained in the same manner as the acrylic resin A except that the physical properties of the acrylic resin B were measured.

(Acrylic resin C)
Trimellitic acid ester (“Adekasizer C-880” manufactured by Asahi Denka Kogyo Co., Ltd .; viscosity at 25 ° C. = 176 mPa · s; weight loss rate at 130 ° C. for 24 hours = 0.09%) was used as the plasticizer. Except for the above, the acrylic resin C was obtained in the same manner as the acrylic resin A, and the physical properties of the acrylic resin C were measured.

  The physical properties of the acrylic resin are as shown in Table 1 below.

The resin compositions of Examples 1-8 and Comparative Examples 1-11 were prepared as follows.
50 parts of any of acrylic resins A to C, 50 parts of resin monomer (details of resin monomers used will be described later), 0.08 part of polyfunctional monomer 1,6-hexanediol diacrylate, thermal polymerization Initiator bis (4-t-butylcyclohexyl) peroxydicarbonate (“PARCADOX 16” manufactured by Kayaku Akzo, 10 hours half-life temperature 44 ° C.) 1 part, polymer phenolic antioxidant (Asahi Denka) "Adekastab AO-60", molecular weight 1178), 0.05 part by sulfur, antioxidant (Adekastab AO-412S, manufactured by Asahi Denka Co., Ltd., molecular weight 1162), 0.05 part, round shape that is a thermally conductive filler 300 parts of aluminum oxide (“AS-10” manufactured by Showa Denko KK, thermal conductivity 30 W / m · K, average particle size 39 μm), and heat transfer that also functions as a flame retardant 100 parts of aluminum hydroxide (“H-32” manufactured by Showa Denko KK), which is a conductive filler, was uniformly kneaded (this kneaded product is referred to as “raw material for heat dissipation material”). Next, after defoaming the heat-dissipating material composition, the resin monomer was poured into a release-treated glass cell set to have a thickness of 2 mm after polymerization and curing. The cell was placed in an oven and heated at 100 ° C. for 60 minutes, and further heated at 120 ° C. for 30 minutes to polymerize the resin monomer to produce a heat conductive sheet as a heat dissipation material.

  The resin monomers used in Examples 1 to 8 and Comparative Examples 1 to 11 are as follows (Tg in each resin monomer represents the glass transition temperature of the homopolymer). In Example 1, diethylene glycol butyl ether methacrylate (Tg—68 ° C.), in Example 2, diethylene glycol hexyl ether methacrylate (Tg—72 ° C.), and in Example 3, diethylene glycol (2-ethylhexyl) ether acrylate (2-ethylhexyl-produced by Kyoeisha Chemical Co., Ltd.) Diglycol acrylate “light acrylate EHDG-A”, Tg −78 ° C., diethylene glycol dodecyl ether methacrylate (Tg −75 ° C.) in Example 4, tetraethylene glycol nonyl phenyl ether acrylate (nonylphenol EO manufactured by Kyoeisha Chemical Co., Ltd.) in Example 5 Adduct acrylate “light acrylate NP-4EA”, Tg −30 ° C.), in Example 6, tetraethylene glycol dodecyl ether acrylate ( Lauroxy polyethylene glycol monoacrylate “Blenmer ALE-200”, Tg of −35 ° C., manufactured by the present fats and oils company. ”, Tg −25 ° C.), in Example 8, decaethylene glycol dodecyl ether methacrylate (Tg—74 ° C.), in Comparative Example 1, ethylene glycol methyl ether acrylate (2-methoxyethyl acrylate“ 2-MTA ”manufactured by Osaka Organic Chemical Industry Co., Ltd.) ”, Tg—50 ° C.), in Comparative Example 2, ethylene glycol ethyl ether acrylate (2-ethoxyethyl acrylate“ 2-ETA ”manufactured by Osaka Organic Chemical Industry Co., Ltd., Tg—56 ° C.), Comparative Example 3 Is diethylene glycol ethyl ether methacrylate (Tg-65 ° C.), in Comparative Example 4, diethylene glycol ethyl ether acrylate (Kyoeisha Chemical Co., Ltd. ethoxy-diethylene glycol acrylate “light acrylate EC-A”, Tg-71 ° C.), in Comparative Example 5, diethylene glycol octadecyl ether Methacrylate (Tg −38 ° C.), in Comparative Example 6 tetraethylene glycol octadecyl ether methacrylate (Nippon Yushi Co., Ltd. stearoxy polyethylene glycol monomethacrylate “Blenmer PSE-200”, Tg −5 ° C.), in Comparative Example 7 decaethylene glycol butyl ether Methacrylate (Tg −78 ° C.), in Comparative Example 8, pentaoxyethylene pentaoxypropylene glycol nonylphenyl ether Acrylate (Nonylphenoxy poly (ethylene glycol-propylene glycol) monoacrylate “Blenmer 43ANEP-500”, manufactured by NOF Corporation, Tg—45 ° C.), in Comparative Example 9, octaoxyethylene hexaoxypropylene glycol (2-ethylhexyl) ether acrylate ( Octyloxypolyethylene glycol polypropylene glycol monomonoacrylate “Blemmer 50AOEP-800B”, Tg −42 ° C., manufactured by NOF Corporation, 2-hydroxy-3-phenoxypropyl acrylate (“Epoxy ester M-600A” manufactured by Kyoeisha Chemical Co., Ltd.) in Comparative Example 10 In Comparative Example 11, 2-ethylhexyl acrylate (Tg-61 ° C.) was used as a resin monomer.

  The resin monomers used in Examples 1, 2, 4, and 8 and Comparative Examples 3, 5, and 7 are resin monomers obtained by synthesis as follows.

  Into a flask equipped with a stirrer, thermometer, reflux condenser, and mixed gas introduction tube of air and nitrogen, toluene, polyoxyethylene alkyl ether, methyl methacrylate (hereinafter referred to as “MMA”), and dibutyl as a catalyst Tin oxide (hereinafter referred to as “DBTO”) and polymerization inhibitor 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter referred to as “H-TEMPO”) were added ( The input amount of each compound is described later). The temperature inside the flask was increased to 110 ° C. while stirring. While maintaining heating and stirring of the temperature in the flask, a synthesis reaction of polyoxyethylene alkyl ether methacrylate was carried out while distilling off the produced methanol (transesterification reaction product of polyoxyethylene alkyl ether and MMA). Thereafter, unreacted MMA and toluene were distilled off to obtain a resin monomer.

  The amount of compound charged into the flask in the synthesis of the resin monomer is as follows. In the synthesis of the resin monomer in Example 1, 300 parts of toluene, 162 parts of polyethylene ethylene alkyl ether diethylene glycol monobutyl ether (average added mole number of ethylene glycol 2), MMA 400 parts, DBTO 4.5 parts , H-TEMPO was 0.030 part. In the synthesis of the resin monomer of Example 2, 400 parts of toluene, 190 parts of diethylene glycol monohexyl ether which is a polyoxyethylene alkyl ether (average added mole number of ethylene glycol 2), 400 parts of MMA, and 4.7 parts of DBTO Part, H-TEMPO was 0.035 part. In the synthesis of the resin monomer of Example 4, 500 parts of toluene, 274 parts of diethylene glycol monododecyl ether (average number of added moles of ethylene glycol 2), which is a polyoxyethylene alkyl ether, 400 parts of MMA, 5.4 parts of DBTO Part, H-TEMPO was 0.045 part. In the synthesis of the resin monomer of Example 8, 1000 parts of toluene, 624 parts of polyoxyethylene alkyl ether decaethylene glycol monododecyl ether (average number of moles of ethylene glycol added 10), MMA 400 parts, DBTO 8 parts .2 parts and H-TEMPO was 0.080 parts. In the synthesis of the resin monomer of Comparative Example 3, 250 parts of toluene, 134 parts of polyethylene ethylene alkyl ether diethylene glycol monoethyl ether (average number of moles of ethylene glycol added 2), MMA 400 parts, DBTO 4.2 parts , H-TEMPO was 0.025 part. In the synthesis of the resin monomer of Comparative Example 5, 400 parts of toluene, 356 parts of diethylene glycol monostearyl ether (average added mole number of ethylene glycol 2), which is a polyoxyethylene alkyl ether, 400 parts of MMA, and 6.1 parts of DBTO Part, H-TEMPO was 0.060 part. In the synthesis of the resin monomer of Comparative Example 7, 1000 parts of toluene, 514 parts of polyoxyethylene alkyl ether decaethylene glycol monobutyl ether (average number of moles of ethylene glycol added 10), MMA 400 parts, DBTO 7. 3 parts, H-TEMPO was 0.070 parts.

  The heat conductive sheets of Examples and Comparative Examples were evaluated for strength, odor, thermal conductivity, hardness, durability, and productivity. The details of these evaluation methods are as follows.

(Strength)
The thermally conductive sheet cut into a size of 5 mm × 40 mm was folded in half to 5 mm × 20 mm, and the state of the bent portion was visually observed. In this observation, “◯” indicates that there is no crack in the bent portion, “Δ” indicates that the crack has occurred, and “×” indicates that the crack is completely broken.

(Odor)
The odor of the heat conductive sheet was evaluated by a sensory test by an examiner. The evaluation standards for odor were “◯” when there was almost no odor, and “X” when there was a strong odor.

(Thermal conductivity)
The thermal conductivity at 25 ° C. of five thermal conductive sheets laminated was measured with a rapid thermal conductivity meter (“QTM-500” manufactured by Kyoto Electronics Industry Co., Ltd.).

(hardness)
According to JIS K7312, the hardness at 25 ° C. was measured using an Asker rubber hardness meter C type manufactured by Kobunshi Keiki Co., Ltd. For the hardness measurement value, the maximum indicated value within one second was adopted by pushing the push needle of a hardness meter into the center of the upper surface of the five heat conductive sheets laminated and bringing the pressure surface into close contact with the sample. In addition, it shows that a heat conductive sheet is rich in flexibility, so that the measured value of hardness is small.

(durability)
The thermally conductive sheet was left in an oven set at 150 ° C., and then the hardness of the sheet was measured. The hardness measurement method here was the same as the method according to JIS K7312. The durability of this heat conductive sheet indicates that the smaller the hardness change, the better.

(productivity)
Evaluation of productivity was performed visually. The evaluation criteria are “○” for a thermally conductive sheet with no cracks and foaming observed on the surface and inside, and a good appearance, and a thermally conductive sheet with cracks or bubbles observed on the surface or inside. Was marked “x”. Moreover, about the productivity, the heat conductive sheet manufactured by changing the temperature for polymerizing a resin monomer from 100 degreeC to 130 degreeC was also evaluated.

  Table 2 shows the evaluation results of the thermally conductive sheets of Examples 1 to 8. Table 3 shows the evaluation results of the heat conductive sheets of Comparative Examples 1 to 11. In Tables 2 and 3, the raw materials used for each thermally conductive sheet are shown in parts by mass.

  The following can be confirmed from the results of Tables 2 and 3.

(1) The carbon number of the saturated hydrocarbon group in OR ³ representing the average addition mole number (n number) of the OR ² group representing the oxyalkylene group is outside the range of 1 to 10 and OR ³ representing the alkoxy group (C In Comparative Examples 1 to 6 and 10 in which the number) is outside the range of 4 to 12, the strength is insufficient. Moreover, although the comparative example 11 whose C number is outside the range of 4-12 has sufficient intensity | strength, the problem with a strong odor remains. On the other hand, Examples 1 to 8 in which the n number is in the range of 1 to 10 and the C number is in the range of 4 to 12 were sufficient strength and that there was no problem of odor. Can be confirmed.

  (2) In Comparative Examples 7 and 8, although the n number is in the range of 1 to 10 and the C number is in the range of 4 to 12, the C number is a value equal to or less than the n number, so the strength is insufficient. It can be confirmed that it was a result.

  (3) Examples 1 to 8 excellent in strength and odor were low in hardness (rich in flexibility), excellent in durability (small change in flexibility over time), and no plasticizer bleeding was observed ( It was confirmed that the bleed of the plasticizer was suppressed) and that the productivity was excellent. That is, if a resin monomer having an n number in the range of 1 to 10, a C number in the range of 4 to 12, and an n number of less than C is used, the strength, odor, hardness, durability, and plasticizer It can be confirmed in Table 2 that a thermally conductive sheet excellent in bleed suppression and productivity can be produced.

  Thermally conductive sheets were produced using the resin compositions of Examples 9 to 11 different from the resin compositions of Examples 1 to 8, and various evaluations of these sheets were performed. In the manufacturing method of a heat conductive sheet here, only the kind and / or usage-amount of the plasticizer or antioxidant in the manufacturing method of Example 3 were changed. The polymerization initiator used in Example 11 was dilauryl peroxide (“Laurox” manufactured by Kayaku Akzo Corporation, 10 hour half-life temperature 61 ° C.).

  The evaluation results of Examples 9 to 11 are shown in Table 4 together with the evaluation results of Example 3.

  Separately from the resin compositions of Examples 1 to 11, heat conductive sheets were produced using the resin compositions of Examples 12 to 14, and various evaluations of these sheets were performed. Here, in the manufacturing method of a heat conductive sheet, only the kind and usage-amount of the heat conductive filler in the manufacturing method of Example 3 were changed. The aluminum nitride used in Example 13 is “R15” (thermal conductivity yield 120 W / m · K) manufactured by Toyo Aluminum Co., and the boron nitride used in Example 14 is “BN100” manufactured by Kyoritsu Material Co., Ltd. (Thermal conductivity is 50 W / m · K).

  The evaluation results of Examples 12 to 14 are shown in Table 5 together with the evaluation results of Example 3.

  Table 6 shows the relationship between the difference between the n number and the C number and the plasticizer.

As shown in Table 6, the hardness change rate and durability when the pyromellitic acid esters of Examples 2, 7, 3, and 6 were used as plasticizers were between the difference between the C number and the n number. There is no general trend. On the other hand, in the case of using dipentaerythritol C ₈ fatty acid esters of Examples 8,1,5, and 4, the larger the difference between the C number and n the number, confirms that the hardness change ratio was reduced It can be confirmed that the durability is improved.

Claims (12)

  A heat-dissipating material resin composition used as a heat-dissipating material containing a heat conductive filler of 35% by mass or more, comprising α, β-unsaturated carbonyl group, oxyethylene, oxypropylene, and oxybutylene An alkoxy group having an average addition mole number of 1 to 10 composed of one or more selected oxyalkylene groups or a polyoxyalkylene group, and a saturated hydrocarbon group having 4 to 12 carbon atoms; And a resin monomer having a group provided as a partial structure, wherein the saturated hydrocarbon group has a larger number of carbon atoms than the average added mole number of the oxyalkylene group or polyoxyalkylene group. Resin composition for heat dissipation material. A resin composition for a heat radiation material used as a raw material for a heat radiation material containing a heat conductive filler of 35% by mass or more, wherein the α, β-unsaturated carbonyl group represented by the formula (1) is a partial structure. A resin composition for a heat dissipating material, comprising a resin monomer.

[In Formula (1), R ¹ represents a hydrogen atom, an alkyl group, or a hydroxyalkyl group, and X is composed of one or more oxyalkylenes selected from oxyethylene, oxypropylene, and oxybutylene. Represents an oxyalkylene group or polyoxyalkylene group having an average number of added moles of 1 to 10 and an alkoxy group having a saturated hydrocarbon group having 4 to 12 carbon atoms as a partial structure; The number of carbon atoms of the saturated hydrocarbon group in the alkoxy group is larger than the average number of added moles of the group or polyoxyalkylene group. ] A heat-dissipating material resin composition used as a heat-dissipating material containing a heat conductive filler of 35% by mass or more, wherein the α, β-unsaturated carbonyl group represented by the formula (2) is a partial structure. A resin composition for a heat dissipating material, comprising a resin monomer.

[In formula (2), R ¹ represents a hydrogen atom, an alkyl group, or a hydroxyalkyl group, and (OR ² ) n represents one or more oxyalkylenes selected from oxyethylene, oxypropylene, and oxybutylene. Represents an oxyalkylene group or a polyoxyalkylene group composed of: n represents that the average added mole number of oxyalkylene in (OR ² ) n is 1 to 10, OR ³ has 4 to 12 carbon atoms It represents an alkoxy group having a saturated hydrocarbon group, and the number of carbon atoms of the saturated hydrocarbon group in OR ³ is larger than the average added mole number n. ] A resin composition for a heat dissipation material used as a raw material for a heat dissipation material containing a heat conductive filler of 35% by mass or more, wherein an α, β-unsaturated carbonyl group represented by the formula (3) is a partial structure A resin composition for a heat dissipating material, comprising a resin monomer.

[In formula (3), X is an oxyalkylene group or polyoxyalkylene having an average addition mole number of 1 to 10 composed of one or more oxyalkylenes selected from oxyethylene, oxypropylene, and oxybutylene And a group having an alkoxy group having a saturated hydrocarbon group having 4 to 12 carbon atoms as a partial structure, R ⁴ represents a hydroxyl group, an alkoxy group, or a hydroxyalkyl group, and in the above X, an oxyalkylene group Or the carbon number of the saturated hydrocarbon group in the alkoxy group is larger than the average added mole number of the polyoxyalkylene group. ] A heat-dissipating material resin composition used as a heat-dissipating material containing a heat conductive filler of 35% by mass or more, wherein the α, β-unsaturated carbonyl group represented by the formula (4) is a partial structure. A resin composition for a heat dissipating material, comprising a resin monomer.

[In the formula (4), (OR ² ) n represents an oxyalkylene group or a polyoxyalkylene group composed of one or more oxyalkylenes selected from oxyethylene, oxypropylene, and oxybutylene, it is (OR ²⁾ average addition mole number of the oxyalkylene at ⁿ represents that the 1 to 10, OR ³ represents an alkoxy group having a saturated hydrocarbon group having 4 to 12 carbon atoms, R ⁴ is a hydroxyl group, Represents an alkoxy group or a hydroxyalkyl group, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the saturated hydrocarbon group in OR ³ has a larger carbon number than the average added mole number n. It is. ]   The resin composition for heat dissipation materials according to any one of claims 1 to 5, wherein a glass transition temperature in a homopolymer of the resin monomer is 0 ° C or lower.   The resin composition for heat dissipation materials according to any one of claims 1 to 6, comprising a thermal polymerization initiator as a polymerization initiator for polymerizing the resin monomer.   A (meth) acrylic polymer obtained by polymerizing a monomer containing a (meth) acrylic acid alkyl ester having 2 to 18 carbon atoms in the alkyl group, having a Tg of 0 ° C. or less and a hydroxyl value of 5 mgKOH / g The resin composition for heat dissipation materials according to any one of claims 1 to 7, comprising the (meth) acrylic polymer as described above.   The resin composition for a heat radiation material according to claim 8, wherein the (meth) acrylic polymer is a (meth) acrylic polymer obtained by polymerizing a monomer containing 2-ethylhexyl (meth) acrylate.   The resin composition for heat-radiating materials according to any one of claims 1 to 9, comprising a plasticizer having a weight loss rate of 2% by mass or less when placed in a temperature atmosphere at 130 ° C for 24 hours.   When the total amount of the resin monomer, (meth) acrylic polymer, and plasticizer is 100% by mass, the resin monomer is 30 to 80% by mass, the (meth) acrylic polymer is 10 to 50% by mass, The resin composition for heat dissipation materials according to claim 10, wherein the plasticizer is 10 to 40% by mass.   The heat dissipation material which used the resin composition for heat dissipation materials in any one of Claims 1-11 for the raw material.