Curable composition

Abstract

To provide a curable composition comprising a polymer having reactive silicon groups, which shows sufficient adhesive strength after curing, even when heat-conductive filler is highly filled in order to obtain excellent heat conductivity.SOLUTION: A curable composition comprises: a polymer (A) having on average 0.85 or more reactive silicon groups per chain end and having a number average molecular weight exceeding 3,000; and heat conductive filler (B), where, in the curable composition, the polymer (A) is included in an amount of 2-5.9 mass% and the heat conductive filler (B) is included in an amount of 85-94 mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable composition containing a polymer having a reactive silicon group, which exhibits sufficient adhesive strength after curing even when a filler is highly filled to obtain excellent performance.

Background Art

[0002] Organic polymers having a silyl group (hereinafter referred to as "reactive silicon group") having a hydroxyl group or a hydrolyzable group on a silicon atom and capable of forming a siloxane bond are known as moisture-reactive polymers. Since this polymer reacts with moisture in the air or the like in the presence of a curing catalyst to form a rubbery cured product having flexibility, it is used in many industrial products such as sealing materials, adhesives, coating materials, paints, and adhesives.

[0003] In order to obtain such a polymer having a reactive silicon group, for example, a method of hydrosilylating an allyl group-containing organic polymer and a hydrosilane compound in the presence of a metal catalyst can be mentioned. In particular, Patent Documents 1 to 3 disclose a method of combining a Group 8 metal catalyst and a co-catalyst containing a carboxylic acid compound having a specific structure as a method for obtaining an organic polymer having a reactive silicon group with a high silylation rate, and a curable composition containing the polymer obtained by this method is known to exhibit a high modulus.

[0004] The polymers as described above are combined with various additives such as plasticizers, fillers, adhesion-imparting agents, and curing catalysts according to their uses and required properties, and are provided on the market as curable compositions.

[0005] In recent years, with the remarkable performance improvement of electronic devices such as personal computers, mobile phones, and PDAs, as well as lighting and display devices such as LEDs and ELs, the amount of heat generated has also increased significantly. However, in order to efficiently cool the constituent electronic components, a curable composition combining a reactive silicon group-containing compound, a crosslinkable compound for crosslinking it, and a thermally conductive filler has been proposed in Patent Document 4. This curable composition is interposed between a heat-generating body such as an electronic component and a heat-dissipating member and is used for the purpose of efficiently dissipating heat.

[0006] For a curable composition containing a thermally conductive filler, the thermal conductivity improves as the filling amount of the thermally conductive filler increases. Also, in order to make a conductive adhesive used in the assembly of electronic components etc. or the connection method with a substrate a good conductor, silver particles are highly filled, or in order to impart a sufficient flame retardant effect to a flame retardant adhesive, a flame retardant such as aluminum hydroxide powder is highly filled, and there are many cases where it is necessary to highly fill various fillers in a polymer having a reactive silicon group.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] Since there is an increasing demand for high heat dissipation performance as a countermeasure against heat in electronic components such as hybrid vehicles and electric vehicles, the proportion of the thermally conductive filler in the curable composition needs to be increased to the limit. Therefore, the amount of the adhesion-imparting component that contributes to member adhesion of the curable composition has to be reduced to the limit, resulting in the problem of insufficient strength after curing.

[0009] Therefore, an object of the present invention is to provide a curable composition containing a polymer having a reactive silicon group, which exhibits sufficient adhesive strength after curing even when highly filled with a thermally conductive filler in order to obtain excellent thermal conductivity.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that among polymers having a reactive silicon group that exhibit high strength after curing, by using a polymer with an increased silylation rate at the terminal, a curable composition that exhibits good adhesive strength can be obtained even when highly filled with a filler, leading to the present invention.

[0011] That is, the curable composition of the present invention is a curable composition containing a polymer (A) having an average of 0.85 or more reactive silicon groups per terminal and a number average molecular weight exceeding 3,000 and a thermally conductive filler (B), characterized in that in the curable composition, 2 to 5.9% by mass of the polymer (A) and 85 to 94% by mass of the thermally conductive filler (B) are contained.

Effects of the Invention

[0012] The curable composition containing the polymer having a reactive silicon group of the present invention exhibits sufficient adhesive strength after curing even when highly filled with a thermally conductive filler in order to obtain excellent thermal conductivity.

Modes for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail.

[0014] (Reactive silicon group of the reactive silicon group-containing polymer (A)) The reactive silicon group-containing polymer (A) of the present invention has a reactive silicon group represented by the following general formula (1). -SiR 1 3-a X a (1) (In the formula, R 1 represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a triorganosiloxy group represented by R 0 3SiO-. The three R 0 are hydrocarbon groups having 1 to 20 carbon atoms, and they may be the same or different. X represents a hydroxyl group or a hydrolyzable group. a is 1, 2, or 3. For each of R 1 and X, when there are a plurality of them, they may be the same or different.).

[0015] Specific examples of R 1 in the general formula (1) include, for example, a methyl group, an ethyl group, a phenyl group, a methoxymethyl group, a vinyl group, and a phenyl group. Among these, the methyl group is industrially useful.

[0016] X in the general formula (1) represents a hydroxyl group or a hydrolyzable group. The hydrolyzable group is not particularly limited and includes known hydrolyzable groups, such as a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoalkoxy group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, and an alkenyloxy group. Among these, an alkoxy group, an acyloxy group, and an alkenyloxy group are preferred, and an alkoxy group such as a methoxy group or an ethoxy group is more preferred because of its mild hydrolyzability and easy handling.

[0017] a in the general formula (1) means the number of reactive groups on the silicon atom. In order to obtain a cured product having high elongation and high strength, a is preferably 2.

[0018] The reactive silicon group of the general formula (1) is not particularly limited, and examples thereof include a dimethoxymethylsilyl group, a diethoxymethylsilyl group, a trimethoxysilyl group, a triethoxysilyl group, a dimethoxyphenylsilyl group, a methoxymethyldimethoxysilyl group, a methoxymethyldiethoxysilyl group, a triisopropenoxysilyl group, a triacetoxysilyl group, and the like. Among these, a dimethoxymethylsilyl group and a trimethoxysilyl group are preferable because they are easy to synthesize. A trimethoxysilyl group and a methoxymethyldimethoxysilyl group are preferable because high curability can be obtained. A trimethoxysilyl group and a triethoxysilyl group are preferable because a cured product exhibiting a high recovery rate and a low water absorption rate can be obtained.

[0019] The reactive silicon group-containing polymer (A) of the present invention preferably has a reactive silicon group-containing terminal structure represented by the general formula (2): ―OCH2CH2CH2SiR 1 3-a X a (2) (In the formula, R 1 , X, and a are the same as described above.) Having a reactive silicon group-containing terminal structure is preferable. In the general formula (2), there is less steric hindrance around the silicon atom, and the reaction efficiency of the reactive silicon group is good, so good curability is easily obtained. Further, the reactive silicon group of the reactive silicon group-containing polymer (A) of the present invention is preferably located at the terminal of the polymer. The "terminal" referred to here is a site located at the end of the repeating unit constituting the polymer and has a structure different from the repeating unit. By having a reactive silicon group at the terminal, it becomes easy to align the molecular weight between crosslinking points, and an effect of increasing the strength of the cured product obtained by curing the curable composition containing the polymer (A) can be expected.

[0020] The number of silicon groups per terminal of the reactive silicon group-containing polymer (A) of the present invention has a lower limit of an average of 0.85 or more, more preferably 0.90 or more, and particularly preferably 0.95 or more. Thereby, a cured product having sufficient strength can be obtained. Further, the upper limit of the number of silicon groups per terminal is preferably an average of 1.0 or less.

[0021] (Main chain structure of the polymer (A) having a reactive silicon group) The main chain structure of the reactive silicon group-containing polymer (A) of the present invention is not particularly limited, and those having various main chain structures can be used. Specifically, polyoxyalkylene polymers such as polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, polyoxypropylene-polyoxybutylene copolymer, etc.; ethylene-propylene copolymers, polyisobutylene, copolymers of isobutylene and isoprene, etc., polychloroprene, polyisoprene, copolymers of isoprene or butadiene with acrylonitrile and / or styrene, etc., polybutadiene, copolymers of isoprene or butadiene with acrylonitrile and styrene, etc., hydrogenated polyolefin polymers obtained by hydrogenating these polyolefin polymers; polyester polymers obtained by condensation of dibasic acids such as adipic acid with glycols or ring-opening polymerization of lactones; (meth)acrylic acid ester polymers obtained by radical polymerization of (meth)acrylic acid ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate; vinyl copolymers obtained by radical polymerization of monomers such as (meth)acrylic acid ester monomers, vinyl acetate, acrylonitrile, styrene; graft polymers obtained by polymerizing monomers such as (meth)acrylic acid ester monomers, vinyl acetate, acrylonitrile, styrene in the above organic polymers; polysulfide polymers; nylon 6 by ring-opening polymerization of ε-caprolactam, nylon 6.6 by condensation polymerization of hexamethylenediamine and adipic acid, nylon 6.10 by condensation polymerization of hexamethylenediamine and sebacic acid, nylon 11 by condensation polymerization of ε-aminoundecanoic acid, nylon 12 by ring-opening polymerization of ε-aminolauryl lactam, copolyamide polymers such as copolyamide having two or more components of the above nylons; polycarbonate polymers obtained by condensation polymerization of bisphenol A and carbonyl chloride, diallyl phthalate polymers, etc. In the above description, for example, (meth)acrylic acid ester represents acrylic acid ester and / or methacrylic acid ester.

[0022] Among these, saturated hydrocarbon polymers such as polyisobutylene, hydrogenated polyisoprene, and hydrogenated polybutadiene, polyoxyalkylene polymers, and (meth)acrylate (co)polymers are more preferable because they have a relatively low glass transition temperature and the resulting cured products have excellent cold resistance. The glass transition temperature of the reactive silicon group-containing organic polymer (A) of the present invention is not particularly limited, but is preferably 20°C or lower, more preferably 0°C or lower, and particularly preferably -20°C or lower. When the glass transition temperature exceeds 20°C, the viscosity may increase in winter or in cold regions, resulting in poor workability. Also, the flexibility of the cured product may decrease and the elongation may decrease. The glass transition temperature indicates the value measured by DSC.

[0023] In addition, polyoxyalkylene polymers and (meth)acrylate (co)polymers are particularly preferable because they have high moisture permeability and are excellent in deep part curability and further adhesiveness when made into a one-component curable composition. Polyoxyalkylene polymers are more preferable, and polyoxypropylene is even more preferable.

[0024] (Meth)acrylate (co)polymers are useful because they can obtain effects such as improving adhesiveness, heat resistance, weather resistance, and reducing water absorption by variously combining the monomer compositions constituting the polymer. The polyoxyalkylene polymer is a polymer having a repeating unit represented by -R 2 -O- (wherein R 2 is a linear or branched alkylene group having 1 to 14 carbon atoms), and R 2 is more preferably a linear or branched alkylene group having 2 to 4 carbon atoms. -R 2Specific examples of the repeating unit represented by -O- include -CH2O-, -CH2CH2O-, -CH2CH(CH3)O-, -CH2CH(C2H5)O-, -CH2C(CH3)(CH3)O-, -CH2CH2CH2CH2O-, and the like. The main chain structure of the polyoxyalkylene polymer may consist of only one type of repeating unit or two or more types of repeating units. Particularly when used in sealants, adhesives, etc., a polyoxypropylene polymer having 50% by weight or more, preferably 80% by weight or more of the repeating unit of oxypropylene in the polymer main chain structure is preferred because it is amorphous and has a relatively low viscosity.

[0025] The main chain structure of the polyoxyalkylene polymer may be linear or may have a branched chain. When a more flexible and highly extensible cured product is desired, a linear main chain structure is preferred. When having a branched chain, the number of branched chains is preferably 1 to 6 (i.e., the number of terminal hydroxyl groups is 3 to 8), more preferably 1 to 4 (i.e., the number of terminal hydroxyl groups is 3 to 6), and most preferably 1 (i.e., the number of terminal hydroxyl groups is 3). By having a branched chain, the effect of improving the resilience can be obtained.

[0026] The polyoxyalkylene polymer is preferably obtained by a ring-opening polymerization reaction of a cyclic ether compound using a polymerization catalyst in the presence of an initiator. Examples of the cyclic ether compound include ethylene oxide, propylene oxide, butylene oxide, tetramethylene oxide, tetrahydrofuran, and the like. These cyclic ether compounds may be used alone or in combination of two or more. Among these cyclic ether compounds, it is particularly preferable to use propylene oxide because an amorphous and relatively low-viscosity polyether polymer can be obtained.

[0027] As the initiator, specifically, alcohols such as butanol, ethylene glycol, propylene glycol, propylene glycol monoalkyl ether, butanediol, hexamethylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin, trimethylol methane, trimethylol propane, pentaerythritol, sorbitol, etc.; polyoxyalkylene polymers such as polyoxypropylene diol, polyoxypropylene triol, polyoxyethylene diol, polyoxyethylene triol, etc., with a number average molecular weight of 300 to 4,000 can be mentioned.

[0028] As the synthesis method of the polyoxyalkylene polymer, for example, a polymerization method using an alkali catalyst such as KOH, a polymerization method using a transition metal compound - porphyrin complex catalyst such as a complex obtained by reacting an organoaluminum compound shown in JP-A-61-215623 with porphyrin, a polymerization method using a double metal cyanide complex catalyst shown in JP-B-46-27250, JP-B-59-15336, US Patent No. 3278457, US Patent No. 3278458, US Patent No. 3278459, US Patent No. 3427256, US Patent No. 3427334, US Patent No. 3427335, etc., a polymerization method using a catalyst composed of a polyphosphazene salt exemplified in JP-A-10-273512, a polymerization method using a catalyst composed of a phosphazene compound exemplified in JP-A-11-060722, etc. can be mentioned. It is not particularly limited, but due to reasons such as production cost and obtaining a polymer with a narrow molecular weight distribution, the polymerization method using a double metal cyanide complex catalyst is more preferable.

[0029] On the other hand, as the main chain structure of the reactive silicon group-containing polymer (A) of the present invention, a polyoxyalkylene polymer containing a urethane bond and a urea bond in the main chain structure may be used as long as the effects of the present invention are not significantly impaired. Specific examples of such polymers include polyurethane prepolymers.

[0030] The polyurethane prepolymer can be obtained by a known method. For example, it can be obtained by reacting a polyol compound with a polyisocyanate compound. Specific examples of the polyol compound include polyether polyol, polyester polyol, polycarbonate polyol, polyether polyester polyol, and the like.

[0031] Specific examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, methylene-bis(cyclohexyl isocyanate), isophorone diisocyanate, hexamethylene diisocyanate, and the like. Note that the terminal of the polyurethane prepolymer may be either a hydroxyl group or an isocyanate group.

[0032] The cured product obtained from the curable composition using a polymer having a urethane bond, a urea bond, and / or an ester bond in the main chain structure of the reactive silicon group-containing polymer (A) of the present invention may have the main chain cleaved at the urethane bond, urea bond, and / or ester bond portion due to heat or the like, and the strength of the cured product may decrease.

[0033] In some cases, a curing improvement effect may be obtained by including an amide bond in the main chain skeleton of the reactive silicon group-containing polymer (A) of the present invention. Also, when there are many amide bonds, the viscosity of the polymer tends to increase. Further, the viscosity may increase after storage, and the workability of the resulting composition may decrease. Furthermore, the amide bond may be cleaved by heat or the like. Therefore, when the main chain structure contains an amide bond, the average number of amide bonds per molecule is 1 to 10, preferably 1.5 to 5, and more preferably 2 to 3. When the number is less than 1, the curability may not be sufficient, and when the number is more than 10, the polymer may have a high viscosity and be difficult to handle. From the viewpoint of obtaining a curable composition excellent in storage stability and workability, a polyoxyalkylene-based polymer that does not contain a urethane bond, a urea bond, and an amide bond in the main chain structure of the polyoxyalkylene-based polymer (A) of the present invention is most preferred.

[0034] (Method for introducing a silicon group into a polymer (A) containing a reactive silicon group) The polymer (A) containing a reactive silicon group of the present invention is preferably obtained by introducing a reactive silicon group into the polymer by any one of the following methods (a) to (d).

[0035] (a) After converting the terminal hydroxyl group of a hydroxyl group-terminated organic polymer into a carbon-carbon unsaturated group, a hydrosilane represented by the general formula (3): HSiR 1 3-a X a (3) (R 1 , X, and a are the same as described in the general formula (2)) is reacted.

[0036] (b) To the terminal hydroxyl group of a hydroxyl group-terminated organic polymer, an isocyanate alkylsilane compound represented by the general formula (4): OCN-W-SiR 1 3-a X a (4) (W is a divalent organic group. R 1 , X, and a are the same as described above) is reacted.

[0037] (c) After converting the terminal hydroxyl group of a hydroxyl group-terminated organic polymer into a carbon-carbon unsaturated group, a mercaptoalkylsilane compound represented by the general formula (5): HS-W-SiR 1 3-a X a (5) (R 1 , W, X, and a are the same as described above) is reacted.

[0038] (d) After reacting a hydroxyl group-terminated organic polymer with a polyisocyanate compound to synthesize an NCO group-terminated organic polymer, the general formula (6): HNR 3 -W-SiR 1 3-a X a (6) (R 3is hydrogen or an alkyl group. R 1 , W, X, and a are the same as described above respectively) or a general formula (7): HS-W-SiR 1 3-a X a (7) (R 1 , W, X, and a are the same as described above respectively) and reacting with a silane compound represented by the formula.

[0039] In the methods (a) and (c) above, examples of the terminal carbon-carbon unsaturated group include a vinyl group, an allyl group, a methallyl group, an arylenyl group, a propargyl group, etc. In order to obtain the structure represented by the general formula (2), a polymer having an allyl group at the terminal can be used in the method (a). In any of the above methods, the polymer (A) obtained using a silane compound in which W is methylene exhibits very high curability.

[0040] The method (a) tends to give a polymer with good storage stability and is preferred. The methods (b), (c), and (d) are preferred because a high conversion rate can be obtained in a relatively short reaction time.

[0041] Regarding the introduction of a reactive silicon group by the method (a), it is proposed in various publications such as Japanese Patent Publication No. Sho 45-36319, Sho 46-12154, Japanese Unexamined Patent Publication No. Sho 50-156599, Sho 54-6096, Sho 55-13767, Sho 55-13468, Sho 57-164123, Japanese Patent Publication No. Hei 3-2450, US Patent No. 3632557, US Patent No. 4345053, US Patent No. 4366307, US Patent No. 4960844, etc., and also proposed in Japanese Unexamined Patent Publication No. Sho 61-197631, Sho 61-215622, Sho 61-215623, Sho 61-218632, which introduce a reactive silicon group by hydrosilylation or the like into a polyoxypropylene polymer having a high molecular weight with a number average molecular weight of 6,000 or more and a narrow molecular weight distribution with Mw / Mn of 1.6 or less, and those proposed in Japanese Unexamined Patent Publication No. Hei 3-72527 can be exemplified.

[0042] When adding hydrosilane to an allyl group by the method of (a), the catalyst for the hydrosilylation reaction is not particularly limited, and examples include metals such as iron, cobalt, nickel, iridium, platinum, palladium, rhodium, ruthenium, and their complexes. Among these, when using a platinum-based hydrosilylation catalyst such as the Karstedt catalyst (platinum divinyldisiloxane complex) described in the above reference, side reactions such as isomerization to a 1-propenyl group (internal olefin) and formation of a propenyl group by hydrogenation are known to occur, and this side reaction will reduce the introduction rate of the reactive silicon group to the allyl group (average number of reactive silicon groups per terminal). As a method for suppressing such side reactions and improving the introduction rate of the reactive silicon group, it has been proposed to use a ruthenium complex having a specific ligand as described in JP-A-2021-11456.

[0043] In order to obtain a polymer in which the number of silicon groups per terminal of the polymer is 0.85 or more on average, which is a condition of the reactive silicon group-containing polymer (A) of the present invention, it is preferable to use these methods. Specific examples include a method of using a ruthenium complex and a halogen-substituted olefin compound (such as 1,4-dibromobenzene, 1-bromo-3,5-difluorobenzene, 1-bromo-2,6-difluorobenzene, 1,4-diiodobenzene, and 1,3,5-tribromobenzene) in the hydrosilylation reaction. The number of silicon groups per terminal of the reactive silicon group-containing polymer (A) of the present invention has a lower limit of 0.85 or more on average, more preferably 0.90 or more, and particularly preferably 0.95 or more.

[0044] (Thermally conductive filler (B)) The curable composition of the present invention contains a thermal conductivity filler (B). As the thermal conductivity filler, a generally commercially available good thermal conductivity filler can be used. Among them, from the viewpoints such as the thermal conductivity, availability, insulation property, electromagnetic wave shielding property, electromagnetic wave absorption property, and the ability to impart specific electrical properties, carbon compounds such as graphite and diamond; metal oxides such as aluminum oxide, magnesium oxide, beryllium oxide, titanium oxide, zirconium oxide, and zinc oxide; metal nitrides such as boron nitride, aluminum nitride, and silicon nitride; metal carbides such as boron carbide, aluminum carbide, and silicon carbide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; metal carbonates such as magnesium carbonate and calcium carbonate; crystalline silica; organic polymer fired products such as acrylonitrile-based polymer fired products, furan resin fired products, cresol resin fired products, polyvinyl chloride fired products, sugar fired products, and charcoal fired products; composite ferrites with Zn ferrite; Fe-Al-Si-based ternary alloys; metal powders, etc. are preferably mentioned.

[0045] Furthermore, from the viewpoints of availability and thermal conductivity, graphite, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon carbide, aluminum hydroxide, magnesium carbonate, and crystallized silica are more preferable, and graphite, α-alumina, hexagonal boron nitride, aluminum nitride, aluminum hydroxide, Mn-Zn-based soft ferrite, Ni-Zn-based soft ferrite, Fe-Al-Si-based ternary alloy (Sendust), carbonyl iron, and iron-nickel alloy (Permalloy) are more preferable. Spheroidized graphite, rounded or spherical α-alumina, spheroidized hexagonal boron nitride, aluminum nitride, aluminum hydroxide, Mn-Zn-based soft ferrite, Ni-Zn-based soft ferrite, spherical Fe-Al-Si-based ternary alloy (Sendust), and carbonyl iron are particularly preferable.

[0046] When carbonyl iron is used in the present invention, it is desirable that it is reduced carbonyl iron powder. Reduced carbonyl iron powder is carbonyl iron powder classified into a reduced grade rather than a standard grade, and is characterized by having a lower carbon and nitrogen content compared to the standard grade.

[0047] In addition, these thermal conductivity fillers are preferably surface-treated with a silane coupling agent (vinyl silane, epoxy silane, (meth)acrylic silane, isocyanate silane, chloro silane, amino silane, etc.), a titanate coupling agent (alkoxy titanate, amino titanate, etc.), or a fatty acid (saturated fatty acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, etc., unsaturated fatty acids such as sorbic acid, elaidic acid, oleic acid, linoleic acid, linolenic acid, erucic acid, etc.) or a resin acid (abietic acid, pimaric acid, levopimaric acid, neoabietic acid, palustric acid, dehydroabietic acid, isopimaric acid, sandaracopimaric acid, colmic acid, seco-dehydroabietic acid, dihydroabietic acid, etc.) from the viewpoint of improving the dispersibility in the polymer (A) having a reactive silicon group.

[0048] Among these, some thermal conductivities are, for example, silica is 1.5 W / mK, alumina is 20 W / mK, magnesium oxide is 40 W / mK, boron nitride is 60 W / mK, aluminum nitride is 70 W / mK, copper is 398 W / mK, aluminum is 237 W / mK, etc., showing good thermal conductivities.

[0049] As the amount of such a thermal conductivity filler used, from the viewpoint of increasing the thermal conductivity of the thermal conductive material obtained from the composition of the present invention, it is preferable that the volume ratio (%) of the thermal conductivity filler is 25% by volume or more in the whole composition. When it is less than 25% by volume, the thermal conductivity tends to be insufficient. When a higher thermal conductivity is desired, it is more preferable that the amount of the thermal conductivity filler used is 40% by volume or more in the whole composition.

[0050] Here, the volume ratio (%) of the thermal conductivity filler is calculated from the weight fraction and specific gravity of each of the resin component and the thermal conductivity filler, and is obtained by the following formula. In the following formula, the thermal conductivity filler is simply described as "filler". Filler volume ratio (capacity %) = (filler weight ratio / filler specific gravity) ÷ [(resin component weight ratio / resin component specific gravity) + (filler weight ratio / filler specific gravity)] × 100 Here, the resin component refers to all components excluding the thermally conductive filler, specifically, the polymer (A) having a reactive silicon group and various additives such as other plasticizers.

[0051] In addition, as a method for increasing the filling rate of the thermally conductive filler with respect to the polymer (A) having a reactive silicon group, it is preferable to use two or more types of thermally conductive fillers having different particle diameters in combination. In this case, it is preferable that the thermally conductive filler having a large particle diameter exceeds 10 μm, and the thermally conductive filler having a small particle diameter is 10 μm or less.

[0052] In addition, these thermally conductive fillers can be used not only as the same type of thermally conductive filler, but also in combination of two or more different types. Also, various fillers other than the thermally conductive filler may be used as needed to the extent that the effects of the present invention are not impaired. The various fillers other than the thermally conductive filler are not particularly limited, but include wood powder, pulp, cotton chips, asbestos, glass fiber, carbon fiber, mica, walnut shell powder, rice husk powder, diatomaceous earth, clay, silica (fumed silica, precipitated silica, fused silica, dolomite, anhydrous silicic acid, hydrous silicic acid, amorphous spherical silica, etc.), reinforcing fillers such as carbon black; diatomaceous earth, calcined clay, clay, talc, titanium oxide, bentonite, organic bentonite, ferric oxide, aluminum fine powder, flint powder, activated zinc white, zinc powder, zinc carbonate, and fillers such as resin powders such as shirasu balloon, glass microballoon, organic microballoon of phenolic resin or vinylidene chloride resin, PVC powder, PMMA powder; fibrous fillers such as asbestos, glass fiber and glass filament, carbon fiber, Kevlar fiber (registered trademark), polyethylene fiber, etc. Among these fillers, precipitated silica, fumed silica, fused silica, dolomite, carbon black, titanium oxide, talc, etc. are preferable. Note that some of these fillers have a slight function as a thermally conductive filler, and some, such as carbon fiber, various metal powders, various metal oxides, and various organic fibers, can be used as excellent thermally conductive fillers depending on their composition, synthesis method, crystallinity, and crystal structure.

[0053] (Curing catalyst) The curable composition of the present invention can be added with a curing catalyst. It is a component for promoting the reaction of hydrolyzing and condensing the reactive silicon group, that is, the curing reaction.

[0054] As the curing catalyst, conventionally known ones can be used. Specifically, organic tin compounds, metal carboxylates, amine compounds, carboxylic acids, alkoxy metals, inorganic acids, mixtures thereof, etc. can be used.

[0055] Specific examples of the organotin compounds include dibutyltin dilaurate, dibutyltin dioctanoate, dibutyltin bis(butyl maleate), dibutyltin diacetate, dibutyltin oxide, dibutyltin bis(acetylacetonate), a reaction product of dibutyltin oxide and a silicate compound, a reaction product of dibutyltin oxide and a phthalic acid ester, dioctyltin diacetate, dioctyltin dilaurate, dioctyltin bis(ethyl maleate), dioctyltin bis(octyl maleate), dioctyltin bis(acetylacetonate), dioctyltin distearate, dioctyltin oxide, a reaction product of dioctyltin oxide and a silicate compound, etc. Due to the recent increasing interest in the environment, dioctyltin compounds are preferred.

[0056] Specific examples of the metal carboxylates include tin carboxylate, bismuth carboxylate, titanium carboxylate, zirconium carboxylate, iron carboxylate, potassium carboxylate, calcium carboxylate, etc. As the carboxyl group, various metals can be combined with the following carboxylic acids.

[0057] Specific examples of the amine compounds include amines such as octylamine, 2-ethylhexylamine, laurylamine, stearylamine, piperidine, 4-methylpiperidine, hexamethyleneimine; nitrogen-containing heterocyclic compounds such as pyridine, 1,8-diazabicyclo[5,4,0]undecene-7 (DBU), 1,5-diazabicyclo[4,3,0]nonene-5 (DBN); guanidines such as guanidine, phenylguanidine, diphenylguanidine; biguanides such as butylbiguanide, 1-o-tolylbiguanide, 1-phenylbiguanide; ketimine compounds, etc.

[0058] Specific examples of the carboxylic acids include acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, lauric acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, etc.

[0059] Specific examples of the metal alkoxide include titanium compounds such as tetrabutyl titanate, titanium tetrakis(acetylacetonate), titanium ethyl acetoacetate, diisopropoxytitanium bis(ethylacetoacetate); aluminum compounds such as aluminum tris(acetylacetonate), diisopropoxyaluminum ethyl acetoacetate; and zirconium compounds such as zirconium tetrakis(acetylacetonate).

[0060] As other curing catalysts, fluoride anion-containing compounds, photoacid generators, and photobase generators can also be used.

[0061] Two or more different types of catalysts may be used in combination. For example, combining the above-mentioned amine compound with a carboxylic acid or combining an amine compound with a metal alkoxide may have the effect of improving reactivity.

[0062] The blending amount of the curing catalyst is preferably 0.001 to 20 parts by weight, more preferably 0.01 to 15 parts by weight, and particularly preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the polymer having a reactive silicon group according to the present invention. Further, in some cases, after the curable composition is cured, it may ooze out onto the surface of the cured product or contaminate the surface of the cured product. In such a case, by setting the amount of the curing catalyst used to 0.01 to 3.0 parts by weight, the surface state of the cured product can be kept good while ensuring curability.

[0063] (Plasticizer) The curable composition of the present invention can contain a plasticizer. The plasticizer is not particularly limited, and specific examples include phthalic acid ester compounds such as dibutyl phthalate, diisononyl phthalate (DINP), diheptyl phthalate, di(2-ethylhexyl) phthalate, diisodecyl phthalate (DIDP), butyl benzyl phthalate; terephthalic acid ester compounds such as bis(2-ethylhexyl)-1,4-benzenedicarboxylate; non-phthalic acid ester compounds such as diisononyl 1,2-cyclohexanedicarboxylate; aliphatic polycarboxylic acid ester compounds such as dioctyl adipate, dioctyl sebacate, dibutyl sebacate, diisodecyl succinate, tributyl acetyl citrate; unsaturated fatty acid ester compounds such as butyl oleate, methyl acetyl ricinoleate; phenyl alkyl sulfonate; phosphate ester compounds; trimellitic acid ester compounds; chlorinated paraffin; hydrocarbon oils such as alkyl diphenyl and partially hydrogenated terphenyl; process oil; epoxy plasticizers such as epoxidized soybean oil and benzyl epoxy stearate, etc.

[0064] Further, the plasticizer may be a high molecular weight plasticizer. Specific examples of the high molecular weight plasticizer include vinyl polymers; polyester plasticizers; polyether polyols such as polyethylene glycol and polypropylene glycol having a number average molecular weight of 500 or more, and derivatives obtained by converting the hydroxy groups of these polyether polyols into ester groups, ether groups, etc., such as polyethers; polystyrenes; polybutadiene, polybutene, polyisobutylene, butadiene-acrylonitrile, polychloroprene, etc. The plasticizer may be used alone or in combination of two or more.

[0065] In addition, the polymer plasticizer may not have a reactive silicon group, but may also have a reactive silicon group. When it has a reactive silicon group, it acts as a reactive plasticizer and can prevent the migration of the plasticizer from the cured product. When it has a reactive silicon group, the average number per molecule is preferably 1 or less, more preferably 0.8 or less. When using a plasticizer having a reactive silicon group, its number average molecular weight is preferably lower than that of the polymer (A) having a reactive silicon group.

[0066] The amount of the plasticizer used is preferably 5 to 150 parts by weight, more preferably 10 to 120 parts by weight, and still more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0067] (Filler) Various fillers can be blended in the curable composition according to the present invention. Examples of the filler include heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, diatomaceous earth, clay, talc, titanium oxide, anhydrous silicic acid, hydrous silicic acid, ferric oxide, aluminum fine powder, zinc oxide, activated zinc white, PVC powder, PMMA powder, glass fiber, filament, and reinforcing filler.

[0068] The reinforcing filler is generally known as a rubber reinforcing filler, and known ones can be used. The reinforcing filler improves the mechanical properties of the cured product and increases the modulus and breaking strength, and is applied to sealants for automotive glass that require strength.

[0069] Specific examples of the reinforcing filler include carbon blacks such as channel black, furnace black, thermal black, lamp black, and acetylene black, and silicas such as fumed silica, precipitated silica, crystalline silica, and fused silica. These may be used alone or in combination of multiple types.

[0070] Examples of carbon black include Printex30, Printex25, HIBLACK30, HIBLACK10, HIBLACK5L, HIBLACK20L, HIBLACK30L (manufactured by Orion Engineered Carbons), Monarch M430, Monarch M570 (manufactured by Cabot), SHOW BLACK N-219, SHOW BLACK N-220 (manufactured by Showa Cabot), Nitron #200, #300, HTC #SL (manufactured by Shin Nippon Carbon), Asahi #120, Asahi #55, Asahi #60, Asahi #70, Asahi Thermal, Asahi #15 (manufactured by Asahi Carbon), Seast S (manufactured by Tokai Carbon), Diablack SA, Diablack N234 (manufactured by Mitsubishi Chemical), Statex N121 (Columbia Carbon Japan), HTC #20 (manufactured by Shin Nippon Carbon), Huber N-907 (manufactured by Huber), Denka acetylene black (manufactured by Denki Kagaku Kogyo), etc. Among carbon blacks, carbon black with a small primary particle size is preferred, and the primary particle size is preferably 10 nm or more and 80 μm or less, more preferably 15 nm or more and 50 μm or less. The reinforcing filler may be used alone or in combination of multiple types.

[0071] The amount of the filler used is preferably 1 to 300 parts by weight, more preferably 10 to 250 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0072] For the purpose of reducing the weight (lowering the specific gravity) of the composition, organic balloons and inorganic balloons may be added. A balloon is a spherical filler with a hollow interior, and examples of the material of this balloon include inorganic materials such as glass, shirasu, and silica, and organic materials such as phenolic resin, urea resin, polystyrene, and saran.

[0073] The amount of the balloon used is preferably 0.1 to 100 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0074] (Adhesion promoter) An adhesion promoter can be added to the curable composition according to the present invention. As the adhesion promoter, a silane coupling agent or a reaction product of a silane coupling agent can be added.

[0075] Specific examples of the silane coupling agent include amino group-containing silanes such as γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and (2-aminoethyl)aminomethyltrimethoxysilane; isocyanate group-containing silanes such as γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, α-isocyanatomethyltrimethoxysilane, and α-isocyanatomethyldimethoxymethylsilane; mercapto group-containing silanes such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ-mercaptopropylmethyldimethoxysilane; epoxy group-containing silanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Further, condensates of amino group-containing silanes, condensates of amino group-containing silanes and other alkoxysilanes, etc., condensates of various silane coupling agents; reaction products of amino group-containing silanes and epoxy group-containing silanes, reaction products of amino group-containing silanes and (meth)acrylic group-containing silanes, etc., reaction products of various silane coupling agents can also be used. The above adhesion promoter may be used alone or in combination of two or more.

[0076] The amount of the silane coupling agent used is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0077] (Solvent, diluent) A solvent or a diluent can be added to the curable composition according to the present invention. The solvent and the diluent are not particularly limited, but aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones, ethers, etc. can be used. When using a solvent or a diluent, due to the problem of air pollution when the composition is used indoors, the boiling point of the solvent is preferably 150°C or higher, more preferably 200°C or higher, and particularly preferably 250°C or higher. The above solvent or diluent may be used alone or in combination of two or more.

[0078] (Anti-sagging agent) An anti-sagging agent may be added to the curable composition according to the present invention, if necessary, to prevent sagging and improve workability. The anti-sagging agent is not particularly limited, and examples thereof include polyamide waxes; hydrogenated castor oil derivatives; metal soaps such as calcium stearate, aluminum stearate, and barium stearate. These anti-sagging agents may be used alone or in combination of two or more.

[0079] The amount of the anti-sagging agent used is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0080] (Antioxidant) An antioxidant (anti-aging agent) can be used in the curable composition according to the present invention. The use of an antioxidant can enhance the weather resistance of the cured product. Examples of the antioxidant include hindered phenol-based, monophenol-based, bisphenol-based, and polyphenol-based antioxidants. For example, Irganox 245, Irganox 1010, Irganox 1035, Irganox 1076, Irganox 1135, Irganox 1330, Irganox 1520 (all of the above are manufactured by BASF); SONGNOX 1076 (manufactured by SONGWON), BHT can be mentioned. Similarly, Tinuvin 622LD, Tinuvin 144, Tinuvin 292, CHIMASSORB 944LD, CHIMASSORB 119FL (all of the above are manufactured by BASF); Adeka Stab LA-57, Adeka Stab LA-62, Adeka Stab LA-67, Adeka Stab LA-63, Adeka Stab LA-68 (all of the above are manufactured by ADEKA CORPORATION); Sanol LS-2626, Sanol LS-1114, Sanol LS-744 (all of the above are manufactured by Sankyo Lifetech Co., Ltd.); the hindered amine light stabilizers shown in No Crack CD (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) can also be used. In addition, antioxidants such as SONGNOX 4120, Naugard 445, and OKABEST CLX050 can also be used. Specific examples of the antioxidant are also described in JP-A-4-283259 and JP-A-9-194731.

[0081] The amount of the antioxidant used is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0082] (Physical property modifier) In the curable composition according to the present invention, a physical property modifier for adjusting the tensile properties of the cured product generated as needed may be added. The physical property modifier is not particularly limited. For example, alkylalkoxysilanes such as phenoxytrimethylsilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane; arylalkoxysilanes such as diphenyldimethoxysilane, phenyltrimethoxysilane; alkylisopropenoxysilanes such as dimethyldiisopropenoxysilane, methyltriisopropenoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane; trialkylsilyl borates such as tris(trimethylsilyl) borate, tris(triethylsilyl) borate; silicone varnishes; polysiloxanes and the like. By using the physical property modifier, the hardness when the curable composition according to the present invention is cured can be increased, or conversely, the hardness can be decreased and the elongation at break can be increased. The above physical property modifier may be used alone or in combination of two or more.

[0083] In particular, a compound that generates a compound having a monovalent silanol group in the molecule by hydrolysis has an effect of reducing the modulus of the cured product without deteriorating the stickiness of the surface of the cured product. A compound that generates trimethylsilanol is particularly preferred. Examples of the compound that generates a compound having a monovalent silanol group in the molecule by hydrolysis include derivatives of alcohols such as hexanol, octanol, phenol, trimethylolpropane, glycerin, pentaerythritol, sorbitol, etc., which are silicon compounds that generate silane monoalcohol by hydrolysis. Specifically, phenoxytrimethylsilane, tris((trimethylsiloxy)methyl)propane, etc. can be mentioned.

[0084] The amount of the physical property modifier used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0085] (Adhesion - imparting resin) In the curable composition according to the present invention, an adhesion - imparting resin can be added for the purpose of enhancing the adhesiveness and close adhesiveness to a substrate, or as needed for other purposes. There is no particular limitation on the adhesion - imparting resin, and those commonly used can be used.

[0086] Specific examples include terpene resins, aromatic - modified terpene resins, hydrogenated terpene resins, terpene - phenol resins, phenol resins, modified phenol resins, xylene - phenol resins, cyclopentadiene - phenol resins, coumarone - indene resins, rosin - based resins, rosin ester resins, hydrogenated rosin ester resins, xylene resins, low - molecular - weight polystyrene - based resins, styrene copolymer resins, styrene - based block copolymers and their hydrogenated products, petroleum resins (e.g., C5 hydrocarbon resins, C9 hydrocarbon resins, C5 - C9 hydrocarbon copolymer resins, etc.), hydrogenated petroleum resins, DCPD resins, etc. These can be used alone or in combination of two or more.

[0087] The amount of the adhesion - imparting resin used is preferably 2 to 100 parts by weight, more preferably 5 to 50 parts by weight, and even more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0088] (Compound containing an epoxy group) In the curable composition according to the present invention, a compound containing an epoxy group can be used. When a compound having an epoxy group is used, the resilience of the cured product can be enhanced. Examples of the compound having an epoxy group include epoxidized unsaturated oils and fats, epoxidized unsaturated fatty acid esters, alicyclic epoxy compounds, compounds shown by epichlorohydrin derivatives, and mixtures thereof, etc. Specifically, epoxidized soybean oil, epoxidized linseed oil, bis(2 - ethylhexyl) - 4,5 - epoxycyclohexane - 1,2 - dicarboxylate (E - PS), epoxy octyl stearate, epoxy butyl stearate, etc. can be mentioned. The epoxy compound is preferably used in the range of 0.5 to 50 parts by weight with respect to 100 parts by weight of the polymer having a reactive silicon group according to the present invention.

[0089] (Oxygen-curable substance) In the curable composition according to the present invention, an oxygen-curable substance can be used. Examples of the oxygen-curable substance include unsaturated compounds that can react with oxygen in the air. It reacts with oxygen in the air to form a cured film near the surface of the cured product, and has functions such as preventing stickiness on the surface and adhesion of dust and dirt to the surface of the cured product. Specific examples of the oxygen-curable substance include drying oils typified by tung oil and linseed oil, and various alkyd resins obtained by modifying the compounds; acrylic polymers, epoxy resins, and silicone resins modified with drying oils; 1,2-polybutadiene, 1,4-polybutadiene, and polymers of C5-C8 dienes obtained by polymerizing or copolymerizing diene compounds such as butadiene, chloroprene, isoprene, and 1,3-pentadiene. These may be used alone or in combination of two or more.

[0090] The amount of the oxygen-curable substance used is preferably in the range of 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the polymer having a reactive silicon group according to the present invention. As described in JP-A-3-160053, the oxygen-curable substance is preferably used in combination with a photocurable substance.

[0091] (Epoxy resin) An epoxy resin can be used in combination in the curable composition according to the present invention. The composition added with an epoxy resin is particularly preferable as an adhesive, especially an adhesive for exterior wall tiles. Examples of the epoxy resin include bisphenol A type epoxy resins or novolak type epoxy resins.

[0092] The use ratio of the epoxy resin and the polymer having a reactive silicon group according to the present invention is preferably in the range of 100 / 1 to 1 / 100 in terms of weight ratio, i.e., reactive silicon group-containing polymer / epoxy resin.

[0093] When adding an epoxy resin, a curing agent for curing the epoxy resin can be used in combination with the curable composition according to the present invention. There is no particular limitation on the epoxy resin curing agent that can be used, and generally used epoxy resin curing agents can be used.

[0094] When using a curing agent for the epoxy resin, the amount used is preferably in the range of 0.1 to 300 parts by weight with respect to 100 parts by weight of the epoxy resin.

[0095] In the curable composition according to the present invention, as other additives, a silicon compound, a silicate, a surface property improver, other resins, a flame retardant, a foaming agent, a light stabilizer, an ultraviolet absorber, a photocurable substance may be added. Further, in the curable composition according to the present invention, various additives may be added as necessary for the purpose of adjusting the physical properties of the composition or the cured product. Examples of such additives include, for example, a curability regulator, a radical inhibitor, a metal deactivator, an ozone deterioration inhibitor, a phosphorus-based peroxide decomposer, a lubricant, a pigment, a fungicide, and the like.

[0096] (Preparation of curable composition) The curable composition according to the present invention can also be prepared as a one-component type in which all the compounding components are pre-compounded and sealed for storage and cured by moisture in the air after construction. Separately as a curing agent, components such as a curing catalyst, a filler, a plasticizer, and water are compounded, and it can also be prepared as a two-component type in which the compounded material and the organic polymer composition are mixed before use. From the viewpoint of workability, the one-component type is preferred.

[0097] When the adhesive composition is of the one-component type, since all the compounding components are pre-compounded, it is preferable to dehydrate and dry in advance the compounding components containing moisture before use, or to dehydrate them by means of reduced pressure during compounding and kneading. Further, in addition to the dehydration and drying method, by adding alkoxysilane compounds such as methyltrimethoxysilane, phenyltrimethoxysilane, n-propyltrimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc., the storage stability is further improved.

[0098] The curable composition used in the present invention preferably has its thermal conductivity adjusted to 0.5 W / mK or more, more preferably 1.0 W / mK or more, and still more preferably 2.0 W / mK or more in order to efficiently transfer heat.

[0099] (Use) Although not limited to applications taking advantage of thermal conductivity, it can be further used in various applications such as electrical and electronic component materials for automobiles and home appliances, electrical insulation materials such as insulating coatings for electric wires and cables, and potting agents for electrical and electronics. In particular, when a polyoxyalkylene polymer is used for the polymer (A) having a reactive silicon group, it is suitable because it has excellent heat resistance and oil resistance for automotive parts and the like, and no contact failure due to cyclic siloxane occurs.

[0100] In the following items, preferred embodiments in the present disclosure are listed, but the present invention is not limited to the following items. [1] A curable composition containing a polymer (A) having an average of 0.85 or more reactive silicon groups per terminal and a number average molecular weight exceeding 3,000 and a thermally conductive filler (B), wherein in the curable composition, the polymer (A) is contained in an amount of 2 to 5.9% by mass and the thermally conductive filler (B) is contained in an amount of 85 to 94% by mass. [2] The curable composition according to [1], wherein the average number of reactive silicon groups per terminal of the polymer (A) is 0.90 or more. [3] The curable composition according to [1] or [2], wherein the number average molecular weight of the polymer (A) is 10,000 or more. [4] A cured product obtained by curing the curable composition according to [1].

Examples

[0101] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The number average molecular weight in the examples is the GPC molecular weight measured under the following conditions. Liquid delivery system: HLC-8420GPC manufactured by Tosoh Corporation Column: TSKgel SuperH series manufactured by Tosoh Corporation Solvent: THF (tetrahydrofuran) Molecular weight: Polystyrene conversion Measurement temperature: 40 °C

[0102] The calculation of the ratio of the reactive silicon group, 1-propenyl group, propyl group, or allyl group was performed using the following nuclear magnetic resonance apparatus (NMR). 1 By 1H NMR measurement. Apparatus: AVANCE III HD500 type digital apparatus (manufactured by BRUKER)

[0103] (Synthesis Example 1) Using polyoxypropylene glycol with a number average molecular weight of about 4,500 as an initiator, the polymerization of propylene oxide was carried out with a zinc hexacyanocobaltate glyme complex catalyst to obtain polyoxypropylene (P-1) having a number average molecular weight of 14,300 and a molecular weight distribution Mw / Mn = 1.21 with hydroxyl groups at both ends. 1.2 molar equivalents of sodium methoxide as a 28% methanol solution was added to the hydroxyl groups of the obtained hydroxyl-terminated polyoxypropylene (P-1). After distilling off methanol under reduced pressure, 1.5 molar equivalents of allyl chloride was further added to the hydroxyl groups of the polymer (P-1) to convert the terminal hydroxyl groups into allyl groups. Unreacted allyl chloride was distilled off under reduced pressure. The obtained unpurified polyoxypropylene was mixed and stirred with hexane and water, and then the aqueous phase was removed by centrifugation. Hexane was distilled off under reduced pressure from the remaining hexane solution to obtain allyl group-containing polyoxyalkylene (P-2). To the polymer (P-2), 50 ppm of (bicyclo[2.2.1]hepta-2,5-diene) dichlororuthenium (II) polymer (manufactured by Sigma-Aldrich) and 130 ppm of 2,3-dibromonorbornadiene were added, and the mixture was stirred at 90 °C for 10 minutes. Further, 4.0 molar equivalents of dimethoxymethylsilane was added to the allyl groups of the polymer (P-2), and the mixture was stirred for 1 hour. Volatile components were distilled off under reduced pressure to obtain polymer (A-1). 1 By 1H NMR measurement, it was confirmed that an average of 0.93 dimethoxymethylsilyl groups were introduced per terminal.

[0104] (Synthesis Example 2) To the allyl group-containing polyoxyalkylene (P-2), 50 ppm of an isopropyl alcohol solution containing 3 wt% of platinum in a platinum vinylsiloxane complex was added, 0.9 molar equivalent of dimethoxymethylsilane was added to the allyl groups of the polymer (P-2), and the mixture was stirred for 1 hour. Volatile components were distilled off under reduced pressure to obtain polymer (A'-1). 1 By 1H NMR measurement, it was confirmed that the polymer (A'-1) had an average of 0.83 dimethoxymethylsilyl groups introduced per terminal. The other terminal structures were 0.16 1-propenyl groups and 0.01 propyl groups.

[0105] (Examples 1 to 4, Comparative Examples 1 to 4) Using a vacuum type rotation / revolution propellerless mixer (manufactured by Shin Key Co., Ltd.), a curable composition was prepared according to the composition shown in Table 1. First, a polymer (A-1) having a reactive silicon group, a polymer (A'-1) having a reactive silicon group, and Kaneka SILYL SAT145 (manufactured by Kaneka Corporation: polyoxypropylene polymer) in the amounts described in Table 1, and 45 parts by mass of Hexamoll DINCH (manufactured by BASF: diisononyl 1,2-cyclohexanedicarboxylate), 480 parts by mass of DAW-45 (manufactured by Denka Co., Ltd.: spherical alumina, average particle size:), and 320 parts by mass of Sumikolandum AA-1.5 (manufactured by Sumitomo Chemical Co., Ltd.: polyhedral alumina) were each weighed into a 150 mL plastic container, stirred with a spatula to make it uniform, and further stirred with a vacuum type rotation / revolution propellerless mixer for 5 minutes. Then, Dynasylan VTMO (manufactured by Evonik: vinyltrimethoxysilane), Dynasylan DAMO (manufactured by Evonik: N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), and Neostan U-220H (manufactured by Nitto Kasei Co., Ltd.: dibutyltin bis(acetylacetonate)) in the amounts described in Table 1 were each added, stirred with a spatula to make it uniform, and further stirred under reduced pressure with a vacuum type rotation / revolution propellerless mixer for 1 minute. The resulting mixture was immediately filled into a moisture-proof aluminum cartridge and sealed to obtain a curable composition.

[0106] <Tensile shear strength> An aluminum plate was used as the adherend. At 23°C and a relative humidity of 50%, the curable composition with a thickness of 50 μm was applied to an adhesive surface of 25 mm × 25 mm on the surface of the aluminum plate. After 2 minutes had elapsed since the application, an aluminum plate without the curable composition was pressed against the surface of the aluminum plate coated with the curable composition, and the aluminum plates as adherends were bonded together. The obtained test specimen was cured at 23°C and a relative humidity of 50% for 3 days and then at 50°C for 4 days, and then a tensile shear test (tensile speed: 50 mm / min) was performed using an autograph to measure the stress at break. The results are shown in Table 1.

[0107] <Thermal conductivity> The thermal conductivity shown in this example was measured with the analyzer and conditions shown below. The obtained composition (specimen size: 15 × 15 × 6 mm) was measured for thermal conductivity using a hot disk method thermal property measuring device (TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.).

Table 1

[0108] According to Table 1, the compositions of Examples 1 to 4 containing the polymer (A-1) having an average of 0.93 reactive silicon groups per terminal have a high filling ratio of 85% by mass or more of the heat conductive filler with respect to the total mass of the components. Nevertheless, they have high tensile shear strength. It can be seen that Example 4, which exhibited excellent thermal conductivity of 2.1 W / mK, showed sufficient adhesiveness with a tensile shear strength of 1.76 MPa. On the other hand, the composition of the comparative example containing the polymer (A'-1) having an average of 0.83 reactive silicon groups per terminal has a tensile shear strength of 1.31 MPa even when the ratio of the heat conductive filler is 86.3% by mass (Comparative Example 1) with respect to the total mass of the components. It can be seen that the strength is lower than that of the compositions of any of the examples.

Claims

**Claim 1** A curable composition comprising a polymer (A) having an average of 0.85 or more reactive silicon groups per terminal and a number average molecular weight exceeding 3,000, and a thermally conductive filler (B), wherein in the curable composition, the polymer (A) is contained in an amount of 2 to 5.9% by mass and the thermally conductive filler (B) is contained in an amount of 85 to 94% by mass. **Claim 2** The curable composition according to claim 1, wherein the polymer (A) has an average of 0.90 or more reactive silicon groups per terminal. **Claim 3** The curable composition according to claim 1, wherein the polymer (A) has a number average molecular weight of 10,000 or more. **Claim 4** A cured product obtained by curing the curable composition according to claim 1.

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