JP2015212325A - Heat-dissipating insulating adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting heat-dissipating insulating adhesive composition which has heat dissipation properties and electrical insulation properties and exhibits sufficient adhesive strength when cured.SOLUTION: The heat-dissipating insulating adhesive composition contains a polyurethane resin composition (A), a thermally conductive filler (B), and a thermal polymerization initiator (C). The polyurethane resin composition (A) contains: a polyurethane (a) having a (meth)acryloyl group and a polyoxyalkylene skeleton; and a polymerizable monomer (b) containing (meth)acrylic acid and/or β-carboxyethyl (meth)acrylate, and a polyfunctional (meth)acrylate. The content of the inorganic filler (B) is 250-700 pts.mass based on 100 pts.mass of the polyurethane resin composition (A).

Description

  The present invention relates to a heat dissipating insulating adhesive composition.

  In recent years, the amount of heat generated from electronic components has been increasing as electronic components have been improved in performance, size and density. Thus, heat dissipation measures for electronic components have become very important techniques for maintaining the performance of electronic components and electrical products equipped with the electronic components. As a heat dissipation measure for electronic components, a method of dissipating heat by attaching a heat sink such as a metal heat sink, a heat radiating plate, and a heat radiating fin to the heat generator of the electronic component is employed. And between the heat generating body and the heat radiating body, a heat radiating material for filling a gap between metals is often used for the purpose of efficiently transferring heat.

  As this heat dissipation material, there are a sheet-like molded product and a paste-like composition because of its shape. As the sheet-like molded product, for example, there is a silicone-based or acrylic-based heat-dissipating sheet containing a heat-dissipating filler. There is a heat dissipating gel or a heat dissipating adhesive that is cured by heating.

  Among these, the heat-dissipating adhesive is required to have high thermal conductivity and adhesive strength under various environments or stresses. The higher the density of the heat dissipation filler in the polymer material, the better the heat dissipation of the heat dissipation material.However, the higher the density of the heat dissipation filler in the polymer material, the more the heat dissipation material itself becomes brittle or There was a problem that the adhesive strength with the body deteriorated.

  In order to solve such a problem, an electrically insulating silicone heat conductive adhesive having excellent thermal conductivity and excellent adhesion to a heat generating member and a heat radiating member is disclosed. (Patent Document 1)

  However, although silicone resin is excellent in heat resistance and durability, contact failure is regarded as a problem because it contains low molecular weight siloxane.

JP2010-248349

  The present invention has been made in view of the above-described conventional problems, has heat dissipation and electrical insulation, and is sufficient when cured even if the content of the inorganic filler is larger than the conventional one. Provided is a heat-dissipating insulating adhesive composition capable of maintaining adhesive strength.

The gist of the present invention is the following [1] to [7].
[1] A heat dissipating insulating adhesive composition comprising a polyurethane resin composition (A), a heat conductive filler (B), and a thermal polymerization initiator (C),
The polyurethane resin composition (A) is a polyurethane (a) having a (meth) acryloyl group and a polyoxyalkylene skeleton, (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate, and polyfunctional (meth) acrylate And a polymerizable monomer (b) containing, wherein the content of the inorganic filler (B) is 250 to 700 parts by mass with respect to 100 parts by mass of the polyurethane resin composition (A). Insulating adhesive composition.
[2] Polyurethane (a1) obtained by reacting a compound having a hydroxyl group and a (meth) acryloyl group with a polyurethane having an isocyanato group obtained by reacting a polyoxyalkylene polyol and a polyisocyanate. [1] is any one of polyurethanes (a2) obtained by reacting a compound having an isocyanato group and a (meth) acryloyl group to a polyurethane having a hydroxyl group obtained by reacting a polyoxyalkylene polyol and a polyisocyanate. The heat-dissipating insulating adhesive composition as described.
[3] The heat-radiating insulating adhesive composition according to any one of [1] or [2], wherein the polymerizable monomer (b) further contains an alkyl (meth) acrylate.
[4] The heat-radiating insulating adhesive composition according to any one of [1] to [3], wherein the inorganic filler (B) is selected from aluminum oxide and aluminum hydroxide.
[5] Any of [1] to [4], wherein the polyurethane resin composition (A) contains 10 to 40% by mass of the polyurethane (a) and 60 to 90% by mass of the polymerizable monomer (b). A heat-dissipating insulating adhesive composition according to claim 1.
[6] The heat-radiating insulating adhesive composition according to any one of [1] to [5], wherein the polyurethane (a) has a weight average molecular weight of 10,000 to 300,000.
[7] The content of the thermal polymerization initiator (C) is 0.1 to 5 parts by mass with respect to 100 parts by mass of the polyurethane resin composition (A), according to any one of [1] to [6]. Heat dissipating insulating adhesive composition.

  According to the present invention, there is provided a heat-dissipating insulating adhesive composition that has heat dissipation and electrical insulation, and that can exhibit sufficient adhesive strength even when the content of inorganic filler is larger than conventional ones. can do.

[Heat-dissipating insulating adhesive composition]
The heat-radiating insulating adhesive composition of the present invention includes a polyurethane resin composition (A), a thermally conductive filler (B), and a thermal polymerization initiator (C). The polyurethane resin composition (A) contains a polyurethane (a) having a (meth) acryloyl group and a polyoxyalkylene skeleton and a polymerizable monomer (b), and the polymerizable monomer (b) is polyfunctional. It contains at least (meth) acrylate, (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate. Content of an inorganic filler (B) is 250-700 mass parts with respect to 100 mass parts of polyurethane resin compositions (A).

Incidentally, in the specification and claims, the term "(meth) acryloyl group", the formula radical or formula represented by _"CH 2 = _{CH-CO-" "CH 2 = C (CH 3)} - The group represented by “CO—” means an “isocyanato group”, which means a group represented by the chemical formula “—N═C═O”.

  More preferably, the polyurethane resin composition (A) containing 10 to 40% by mass of the polyurethane (a) having a (meth) acryloyl group and a polyoxyalkylene skeleton and 60 to 90% by mass of the polymerizable monomer (b). 100 parts by mass, 250 to 700 parts by mass of the inorganic filler (B), and 0.1 to 5.0 parts by mass of the thermal polymerization initiator (C).

<Polyurethane resin composition (A)>
The polyurethane resin composition (A) of the present invention comprises a polyurethane (a) having a (meth) acryloyl group and a polyoxyalkylene skeleton and a polymerizable monomer (b), and the polymerizable monomer (b) is A polyfunctional (meth) acrylate is essential, and (meth) acrylic acid and at least one of β-carboxyethyl (meth) acrylate are included. The total content of the polyurethane (a) and the polymerizable monomer (b) with respect to the polyurethane resin composition (A) is preferably 80% by mass or more, more preferably 90% by mass or more, and in some cases 100% by mass. %.

  By setting the total content of polyurethane (a) and polymerizable monomer (b) to 80% by mass or more, the adhesive strength of the heat dissipating insulating adhesive obtained by curing the heat dissipating insulating adhesive composition is maintained high. be able to.

  In addition, the polyurethane resin composition (A) of the present invention contains a polymer other than the polyurethane (a) and the polymerizable monomer (b) to such an extent that the adhesive strength and the electrical insulating function are not affected. It's okay.

  Other polymers include, for example, conjugated diene polymers such as natural rubber, polybutadiene rubber, and polyisoprene rubber; butyl rubber; styrene-butadiene random copolymer, styrene-isoprene random copolymer, and styrene-butadiene-isoprene random copolymer. Aromatic vinyl-conjugated diene copolymers such as polymers, styrene-butadiene block copolymers, styrene-isoprene block copolymers, styrene-butadiene-isoprene block copolymers, styrene-isoprene-styrene block copolymers A hydrogenated aromatic vinyl-conjugated diene copolymer, such as a hydrogenated styrene-butadiene copolymer; a vinyl cyanide compound-conjugated, such as an acrylonitrile-butadiene copolymer rubber, an acrylonitrile-isoprene copolymer rubber; The Copolymer; hydrogenated product of vinyl cyanide compound-conjugated diene copolymer such as hydrogenated product of acrylonitrile-butadiene copolymer; vinyl cyanide-aromatic vinyl-conjugated diene copolymer; vinyl cyanide Compound-aromatic vinyl-conjugated diene copolymer hydrogenated product; vinyl cyanide compound-conjugated diene copolymer and poly (vinyl halide) mixture; polyepichlorohydrin rubber, polyepibromohydrin rubber, etc. Polyepihalohydrin rubber; polyalkylene oxide such as polyethylene oxide and polypropylene oxide; ethylene-propylene-diene copolymer (EPDM); silicone rubber; silicone resin; fluororubber; fluororesin; polyethylene; ethylene-propylene copolymer; Such as ethylene-butene copolymer, Tylene-α-olefin copolymer; α-olefin polymer such as polypropylene, poly-1-butene, poly-1-octene; polyvinyl halide resin such as polyvinyl chloride resin and polyvinyl bromide resin; Polyhalogenated vinylidene resins, such as polyvinylidene chloride resins and polyvinylidene bromide resins; epoxy resins; phenol resins; polyphenylene ether resins; polyamides such as nylon-6, nylon-6,6, nylon-6,12; Polyester, polyvinyl acetate, poly (ethylene-vinyl alcohol), and the like may be used.

(Polyurethane (a))
The polyoxyalkylene polyol used for the production of the polyurethane (a) of the present invention is preferably a polyoxyalkylene polyol having an alkylene chain having 2 to 4 carbon atoms. Preferred polyoxyalkylene polyols include, for example, polyoxyethylene polyol, polyoxypropylene polyol, polyoxybutylene polyol, polytetramethylene ether glycol and the like. These polyoxyalkylene polyols are obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide. The polyoxyalkylene polyol used in the present invention is one kind of alkylene oxide. A copolymer obtained by addition copolymerization of two or more kinds of alkylene oxides may be used in addition to a polymer obtained by addition polymerization of the above.

  The number average molecular weight of the polyoxyalkylene polyol is usually 500 to 5,000, preferably 800 to 4,000, and more preferably 1000 to 3,000. Since the number average molecular weight of the polyoxyalkylene polyol is 500 or more and 5,000 or less, the urethane bond in the polyurethane is secured in a desired amount, so that the heat radiation insulating adhesive composition is cured. The adhesive strength of the conductive insulating adhesive can be increased.

  Although it does not specifically limit as polyisocyanate used for manufacture of the polyurethane (a) of this invention, The compound containing two isocyanato groups is preferable. Polyisocyanates include tolylene diisocyanate and its hydrogenated product, xylylene diisocyanate and its hydrogenated product, diphenylmethane diisocyanate and its hydrogenated product, 1,5-naphthylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, trimethylhexahexan. Examples include diisocyanates such as methylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexyl diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, norbornane diisocyanate, and two or more of these may be used in combination. . Among these, isophorone diisocyanate or diphenylmethane diisocyanate and a hydrogenated product thereof are preferable from the viewpoint of excellent reactivity control.

[First synthesis method of polyurethane (a)]
Next, the first synthesis method of polyurethane (a), that is, the synthesis method of polyurethane (a1) will be described.

  First, a polyoxyalkylene polyol and a polyisocyanate are reacted at a ratio in which the amount of isocyanato groups is larger than the amount of hydroxyl groups to synthesize “polyurethane having isocyanato groups”.

  At this time, it is possible to adjust the molecular weight of the polyurethane having an isocyanato group by adjusting the ratio of the amount of isocyanate group to the amount of hydroxyl group. Specifically, the smaller the ratio of the amount of isocyanate groups to the amount of hydroxyl groups, the larger the molecular weight of the polyurethane having an isocyanate group, and the larger the ratio of the amount of isocyanate groups to the amount of hydroxyl groups, the molecular weight of the polyurethane compound having an isocyanate group. Becomes smaller. Specifically, the amount of isocyanato groups in the polyisocyanate is preferably 1.03 to 1.35 mol, preferably 1.05 to 1.1 mol, per 1 mol of hydroxyl groups in the polyoxyalkylene polyol. More preferably.

Next, a polyurethane having an isocyanato group is reacted with a compound having a hydroxyl group and a (meth) acryloyl group to synthesize a polyurethane (a1).
Although it does not specifically limit as a compound which has a hydroxyl group and (meth) acryloyl group, Hydroxyalkyl (2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. ( 1,3-butanediol mono (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, 3-methylpentanediol mono (meth) acrylate Monools having a (meth) acryloyl group derived from various polyols such as, etc. may be mentioned, and two or more kinds may be used in combination. Among these, 2-hydroxyethyl acrylate is preferable in terms of excellent reactivity with an isocyanato group and thermosetting.

  When a polyurethane having an isocyanato group is reacted with a compound having a hydroxyl group and a (meth) acryloyl group, an alkyl alcohol is added to react with the polyurethane having an isocyanato group, whereby (meta) to the polyurethane (a1) ) The amount of acryloyl group introduced can be adjusted.

  The amount of the (meth) acryloyl group introduced into the polyurethane (a) is usually 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%, based on the isocyanato group. preferable. When the introduction amount of the (meth) acryloyl group is 50 mol% or more and 100 mol% or less with respect to the isocyanato group, the adhesive strength of the heat dissipating insulating adhesive obtained by curing the heat dissipating insulating adhesive composition is expressed. .

  Examples of the alkyl alcohol include, but are not limited to, linear, branched, and alicyclic alkyl alcohols, and specific examples include ethanol, propanol, and butanol.

[Second Synthesis Method of Polyurethane (a)]
Next, the second synthesis method of polyurethane (a), that is, the synthesis method of polyurethane (a2) will be described.

  First, a polyoxyalkylene polyol and a polyisocyanate are reacted at a ratio in which the amount of hydroxyl groups is greater than the amount of isocyanate groups to synthesize “polyurethane having hydroxyl groups”.

  At this time, it is possible to adjust the molecular weight of the polyurethane having hydroxyl groups by adjusting the ratio of the amount of hydroxyl groups to the amount of isocyanate groups. Specifically, the smaller the ratio of the amount of hydroxyl groups to the amount of isocyanate groups, the greater the molecular weight of the polyurethane having hydroxyl groups, and the larger the ratio of the amount of hydroxyl groups to the amount of isocyanate groups, the greater the molecular weight of the polyurethane compound having hydroxyl groups. Becomes smaller. Specifically, the amount of isocyanato groups in the polyisocyanate is preferably 0.83 to 0.97 mol, preferably 0.90 to 0.95 mol, based on 1 mol of the hydroxyl group of the polyoxyalkylene polyol. More preferably.

Next, the polyurethane (a2) is synthesized by reacting the polyurethane having a hydroxyl group with a compound having an isocyanato group and a (meth) acryloyl group.
At this time, the amount of the (meth) acryloyl group introduced into the polyurethane (a2) can be adjusted by adjusting the amount of the compound having an isocyanato group and a (meth) acryloyl group.

  The amount of (meth) acryloyl group introduced into the polyurethane (a2) is usually 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%, based on the hydroxyl group. preferable. When the introduction amount of the (meth) acryloyl group is 50 mol% or more and 100 mol% or less with respect to the hydroxyl group, the adhesive strength of the heat dissipating insulating adhesive obtained by curing the heat dissipating insulating adhesive composition is expressed. .

  Although it does not specifically limit as a compound which has an isocyanato group and a (meth) acryloyl group, 2- (meth) acryloyloxyethyl isocyanate, 1, 1-bis (acryloyloxymethyl) ethyl isocyanate etc. are mentioned, 2 or more types combined use May be. Among these, 2- (meth) acryloyloxyethyl isocyanate is preferable from the viewpoint of excellent reactivity with a hydroxyl group and thermosetting.

  Examples of commercially available products that can be used as a compound having an isocyanato group and a (meth) acryloyl group include “Karenz MOI (registered trademark)” and “Karenz AOI (registered trademark)” manufactured by Showa Denko KK.

In the synthesis of the polyurethane (a), the reaction between the hydroxyl group and the isocyanato group is carried out using a urethanization catalyst such as dibutyltin dilaurate, dibutyltin diethylhexanoate, or dioctyltin dilaurate in the presence of an organic solvent inert to the isocyanato group. Usually, it is continuously performed at 30 to 100 ° C. for about 1 to 5 hours.
The use amount of the urethanization catalyst is usually 50 to 500 ppm by mass with respect to the total mass of the reaction product.

  The weight average molecular weight of the polyurethane (a) of the present invention is preferably 10,000 to 300,000, more preferably 20,000 to 200,000, still more preferably 30,000 to 100,000. It is. Since the weight average molecular weight of the polyurethane (a) is 10,000 or more and 300,000 or less, the adhesive strength of the heat dissipating insulating adhesive obtained by curing the heat dissipating insulating adhesive composition is maintained high, and , Easy handling and improved workability.

  The weight average molecular weight is measured by gel permeation chromatography: trade name “Shodex GPC-101” (manufactured by Showa Denko KK, “Shodex” is a registered trademark). It is.

  It is preferable that content of the polyurethane (a) in a polyurethane resin composition (A) is 10-40 mass%, More preferably, it is 15-35 mass%. When the content of the polyurethane (a) in the polyurethane resin composition (A) is 10% by mass or more and 40% by mass or less, the dispersibility of the heat conductive filler becomes good, the workability is excellent, and further heat dissipation. The adhesive strength of the heat dissipating insulating adhesive obtained by curing the heat insulating insulating composition is maintained high.

(Polymerizable monomer (b))
The polymerizable monomer (b) used in the polyurethane resin composition (A) of the present invention contains polyfunctional (meth) acrylate, (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate. . The polyfunctional (meth) acrylate is a compound having two or more (meth) acryloyloxy groups, and an ester of a polyol and (meth) acrylic acid is preferable. These are not particularly limited, but polyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, α, ω-di (meth) acrylbisdiethylene glycol phthalate, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol Di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diacryloxyethyl methacrylate Examples thereof include phosphate, dipentaerythritol hexa (meth) acrylate, and pentaerythritol tetra (meth) acrylate. The polymerizable monomer (b) may contain at least one kind of (meth) acrylic acid and β-carboxyethyl (meth) acrylate (also referred to as 2-carboxyethyl (meth) acrylate). The polymerizable monomer (b) may contain other polymerizable monomer. Although it does not specifically limit as these polymers, It is preferable to use (meth) acrylic acid ester. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) Alkyl (meth) acrylates such as acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate; cyclohexyl (meth) acrylate, norbornyl (meth) ) Acrylate, isobornyl (meth) acrylate, norbornanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, di Cyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, cyclic alkyl (meth) acrylate such as tricyclodecane dimethylol di (meth) acrylate; ethoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, Alkoxyalkyl (meth) acrylates such as butoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, 2-ethoxyethoxyethyl (meth) acrylate; methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxy Alkoxy (poly) alkylene glycol (meth) acrylate such as dipropylene glycol (meth) acrylate; 2-hydroxyethyl (meth) Chryrate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butanediol mono (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 1,6-hexanediol Hydroxyl group-containing (meth) acrylates such as mono (meth) acrylate and 3-methylpentanediol mono (meth) acrylate; carboxyl group-containing (meth) acrylates such as (meth) acrylic acid and β-carboxyethyl (meth) acrylate; 2-sulfonic acid group-containing (meth) acrylates such as 2-sulfoethyl (meth) acrylate; fluorinated alkyl (meth) acrylates such as octafluoropentyl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N -Diechi N, N-dialkylaminoalkyl (meth) acrylates such as aminoethyl (meth) acrylate ;; (meth) acrylamides such as (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acryloylmorpholine A (meth) acrylate having an epoxy group such as glycidyl (meth) acrylate may be used, and two or more of them may be used in combination.

  The polymerizable monomer (b) is composed of a polyfunctional (meth) acrylate, (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate, from the viewpoint of adhesion and adhesive strength of the heat dissipating insulating adhesive. It is preferable that an alkyl (meth) acrylate is further included. As content of polyfunctional (meth) acrylate, it is preferable that it is 1-10 mass% in a polyurethane resin composition (A). The total content of (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate is preferably 1 to 10% by mass in the polyurethane resin composition (A). The total content of polyfunctional (meth) acrylate and (meth) acrylic acid and / or β-carboxyethyl (meth) acrylate is 1 to 10% by mass in the polyurethane resin composition (A). By this, adhesiveness can fully be ensured, and the adhesive strength when the obtained heat-dissipating insulating adhesive composition is cured is also improved.

  The content of the polymerizable monomer (b) used in the polyurethane resin composition (A) of the present invention is preferably 60 to 90% by mass, more preferably 65 to 85% by mass. When the content of the polymerizable monomer (b) in the heat dissipating insulating adhesive composition is 60% by mass or more and 90% by mass or less, the heat dissipating insulating adhesive composition is cured. Adhesive strength is also improved.

<Inorganic filler (B)>
As the inorganic filler (B) of the present invention, those having relatively high thermal conductivity are preferable. Specifically, although not particularly limited, metal oxides such as aluminum oxide, zinc oxide, and titanium dioxide, nitrides such as aluminum nitride, boron nitride, and silicon nitride, silicon carbide, aluminum hydroxide, and metals such as aluminum Powder etc. are mentioned. These can be used alone or in combination of several kinds. Of these, aluminum oxide and aluminum hydroxide are preferable in terms of ease of handling.

  As content of the inorganic filler (B) of this invention, it is 250-700 mass parts with respect to 100 mass parts of polyurethane resin compositions (A) in a heat-radiating insulating adhesive composition, and is 300-650 mass parts. Preferably there is. When the content of the inorganic filler (B) is 250 parts by mass or more and 700 parts by mass or less, sufficient thermal conductivity is obtained, and the viscosity of the heat dissipating insulating adhesive composition is suppressed from becoming too high. Is done.

  About the particle diameter of an inorganic filler (B), it is preferable that a cumulative mass 50% particle diameter (D50) is 1-50 micrometers. More preferably, it is 3-30 micrometers. When the cumulative mass 50% particle diameter (D50) is 1 μm or more and 50 μm or less, the viscosity of the heat dissipating insulating adhesive composition does not become too high, and the unevenness of the coating surface of the heat dissipating insulating adhesive composition Is suppressed from increasing.

  Here, the “cumulative mass 50% particle size (D50)” is, for example, a laser diffraction type particle size distribution measurement using a laser diffraction type particle size distribution measuring device of trade name “SALD-200VER” manufactured by Shimadzu Corporation. Is obtained.

<Thermal polymerization initiator (C)>
In the present invention, a thermal polymerization initiator (C) capable of curing a dark part such as between metals is used. The thermal polymerization initiator (C) is not particularly limited, and examples thereof include organic peroxides such as dialkyl peroxides, acyl peroxides, hydroperoxides, ketone peroxides, and peroxy esters, and azo compounds. Specific examples of the organic peroxide include t-butyl cumyl peroxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and 2,5-dimethyl-2. , 5-Di (t-butylperoxy) hexyne-3, t-butyl hydroperoxide, methyl ethyl ketone peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) peroxyhexane, di (4-t-butyl) (Cyclohexyl) peroxydicarbonate, t-butyl peroxyneodecanoate Specific examples of the azo compound include azoisobutyronitrile. These may be used alone or in combination of two or more. From the viewpoint of the thermosetting property of the heat dissipating insulating adhesive composition and the adhesive strength when cured, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate or t-butyl peroxy Neodecanoate is preferred.

  The content of the thermal polymerization initiator (C) in the heat dissipating insulating adhesive composition is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the polyurethane resin composition (A). It is more preferably ˜4 parts by mass, and further preferably 0.5-2 parts by mass. The content of the thermal polymerization initiator (C) in the heat dissipating insulating adhesive composition is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the polyurethane resin composition (A). Moreover, it can suppress that the sclerosis | hardenability of a heat-radiating insulating adhesive composition falls, and can suppress that the adhesive strength at the time of hardening a heat-radiating insulating adhesive composition falls.

  The heat dissipating insulating adhesive composition of the present invention may further contain a resin different from the polyurethane (a) in order to improve the adhesion to the substrate.

  The resin is not particularly limited, however, rosin resins such as rosin and rosin esterified products; terpene resins such as diterpene polymers and α-pinene-phenol copolymers; aliphatic (C5), aromatic Petroleum resins such as (C9 series); styrene series resins, phenol series resins, xylene resins and the like may be mentioned, and two or more types may be used in combination.

  The heat-radiating insulating adhesive composition of the present invention may further contain an additive as necessary.

  Although it does not specifically limit as an additive, Light stabilizers, such as a dispersing agent, a plasticizer, a softener, antioxidant, anti-aging agent, an ultraviolet absorber, a polymerization inhibitor, a benzotriazole type, a phosphate ester type, and others Flame retardants, antistatic agents such as surfactants, and the like.

  The method for curing the heat dissipating insulating adhesive composition of the present invention is not particularly limited, but after applying the heat dissipating insulating adhesive composition of the present invention to, for example, a metal substrate, the other metal substrate is bonded. And a method of heat curing. The curing temperature depends on the thermal polymerization initiator used, but is preferably 50 to 150 ° C. The curing time is preferably 5 to 120 minutes, although it depends on the type of thermal polymerization initiator used and the coating thickness of the heat dissipating insulating adhesive composition.

  Although it does not specifically limit as a method of apply | coating the heat-radiating insulating adhesive composition of this invention on a base material, Brush coating, bar coating, air spray, spin coating, dispensing etc. are mentioned.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by an Example. In addition, a part means a mass part.
Polyurethanes (A-1) to (A-3) were synthesized according to the synthesis examples described below.

<Synthesis of polyurethane (A-1)>
Trade name “D-2000”, which is a polypropylene glycol having a terminal end of a hydroxyl group having a hydroxyl value of 56 mgKOH / g in a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube. (Mitsui Chemical Fine Co., Ltd., number average molecular weight: 2000) was charged at a ratio of 15 moles for the former and 14 moles for the latter, and then 100 wtppm of dioctyltin dilaurate was added to isophorone diisocyanate and D-2000. The temperature was raised to 0 ° C. and reacted for 4 hours to obtain a polyurethane having an isocyanato group at the end. Next, after adding 2 mol of 2-hydroxyethyl acrylate to 1 mol of the obtained polyurethane, the temperature is raised to 70 ° C. and reacted for 2 hours, and a polyurethane having an acryloyl group having a weight average molecular weight of 70000 at the terminal (A-1) was obtained. At this time, after confirming that the absorption peak derived from the isocyanato group disappeared by IR spectrum, the reaction was terminated.

<Synthesis of polyurethane (A-2) and (A-3)>
Polyurethanes (A-2) and (A-3) were synthesized in the same manner as polyurethane (A-1) except that the reaction was carried out at the composition and reaction temperature shown in Table 1.

<Weight average molecular weight>
Using gel permeation chromatography (trade name: “Shodex GPC-101” (manufactured by Showa Denko KK), “Shodex” is a registered trademark), the weight average molecular weight was measured under the following conditions.
Column: LF-804 (made by Showa Denko KK)
Column temperature: 40 ° C
Sample: 0.2 mass% tetrahydrofuran solution Flow rate: 1 ml / min
Eluent: Tetrahydrofuran Detector: RI detector

Examples 1-7 Comparative Examples 1-5
Uniform heat dissipation by blending polyurethane resin composition (A), thermal conductive filler (B), and thermal polymerization initiator (C) with the compositions shown in Tables 2-4 and mixing with a disper at room temperature A conductive insulating adhesive composition was prepared.

(Measurement of thermal conductivity)
The prepared heat-dissipating insulating adhesive composition was applied to a release PET film (200 mm × 200 mm × 100 μm) using an applicator so that the film thickness was 200 μm, and then the release PET film (200 mm × 200 mm × 100 μm) was further formed on the upper surface. ) And cured by heating in an oven at 80 ° C. for 30 minutes to obtain a cured product of a heat-dissipating insulating adhesive composition having a film thickness of about 200 μm.

  Using a thermal conductivity measuring instrument (Kyoto Electronics Industry Co., Ltd., rapid thermal conductivity meter, QTM-500), the cured product obtained above was measured for thermal conductivity by the unsteady hot wire comparison method in a 23 ° C atmosphere. Measurements were made. The results are shown in Tables 2-4.

(Measurement of adhesive strength)
After the prepared heat-dissipating insulating adhesive composition is applied to the surface of an aluminum plate (100 mm × 25 mm × 1 mm), another aluminum plate is bonded, and the thickness of the adhesive layer after bonding is 0.2 mm. It was pressed. The bonding area was 12.5 mm × 25 mm. The bonded aluminum plate was heated in an oven at 80 ° C. for 60 minutes to obtain a test specimen.
About the obtained test body, according to JISK6850, the test speed | rate 2.5 mm / min and the tensile shear bond strength in 23 degreeC were measured.

(Measurement of volume resistivity)
The prepared heat-dissipating insulating adhesive composition was applied to a release PET film (200 mm × 200 mm × 100 μm) using an applicator so that the film thickness was 200 μm, and then the release PET film (200 mm × 200 mm × 100 μm) was further formed on the upper surface. ) And cured by heating in an oven at 80 ° C. for 60 minutes to obtain a cured product of a heat-dissipating insulating adhesive composition having a film thickness of about 200 μm.

  Using a resistivity meter (manufactured by Mitsubishi Chemical Corporation, Hiresta UP), the volume resistivity of the cured product of the heat-dissipating insulating adhesive composition obtained above was measured. The results are shown in Tables 2-4.

Claims (7)

A heat-dissipating insulating adhesive composition comprising at least a polyurethane resin composition (A), a thermally conductive filler (B), and a thermal polymerization initiator (C),
The polyurethane resin composition (A) is a polyurethane (a) having a (meth) acryloyl group and a polyoxyalkylene skeleton, at least one of (meth) acrylic acid, β-carboxyethyl (meth) acrylate, and polyfunctional (meth) And a polymerizable monomer (b) containing an acrylate, wherein the content of the inorganic filler (B) is 250 to 700 parts by mass with respect to 100 parts by mass of the polyurethane resin composition (A). Insulating adhesive composition.   Polyurethane (a1) obtained by reacting a compound having a hydroxyl group and a (meth) acryloyl group with a polyurethane having an isocyanato group obtained by reacting a polyoxyalkylene polyol and a polyisocyanate. The heat dissipation according to claim 1, wherein the polyurethane has a hydroxyl group obtained by reacting an alkylene polyol and a polyisocyanate and is a polyurethane (a2) obtained by reacting a compound having an isocyanato group and a (meth) acryloyl group. Insulating adhesive composition.   The heat-dissipating insulating adhesive composition according to claim 1, wherein the polymerizable monomer (b) further contains an alkyl (meth) acrylate.   The heat-radiating insulating adhesive composition according to any one of claims 1 to 3, wherein the inorganic filler (B) is at least one selected from aluminum oxide and aluminum hydroxide.   The heat dissipation according to any one of claims 1 to 4, wherein the polyurethane resin composition (A) contains 10 to 40% by mass of the polyurethane (a) and 60 to 90% by mass of the polymerizable monomer (b). Insulating adhesive composition.   The heat-radiating insulating adhesive composition according to any one of claims 1 to 5, wherein the polyurethane (a) has a weight average molecular weight of 10,000 to 300,000. The heat-radiating insulating adhesive according to any one of claims 1 to 6, wherein the content of the thermal polymerization initiator (C) is 0.1 to 5 parts by mass with respect to 100 parts by mass of the polyurethane resin composition (A). Agent composition.