Condensation-curing type thermally conductive silicone composition and method for producing the same

Abstract

The present invention provides a condensation-curing type thermally conductive silicone composition that hardens with moisture at room temperature, exhibits low hardness of the cured product making it suitable for stress relaxation, and displays stable physical properties during manufacturing. [Solution] A step of surface treatment of the filler by mixing (B) the wetter component and (E) the filler component, followed by heat treatment at 100-180°C for 0.5-5 hours, and then, [ii] A step of mixing (A) a base polymer component, (C) a crosslinking agent component, and (D) a catalyst component with the surface-treated filler obtained in step [i]. This is a method for producing a condensation-curing type thermally conductive silicone composition containing [a specific substance].

Description

[Technical Field]

[0001] The present invention relates to a condensation-curing type thermally conductive silicone composition that hardens with moisture at room temperature and forms a soft cured product (rubber) after curing, and a method for producing the same. [Background technology]

[0002] In fields such as electrical and electronic engineering and transportation, a greater number of control electronic elements and components are being installed than ever before in order to precisely manage energy. For example, even focusing solely on transportation, the shift from gasoline-powered vehicles to hybrid vehicles, plug-in hybrid vehicles, and electric vehicles has necessitated the installation of electronic elements and components such as motors, inverters, and batteries that were not previously required in gasoline-powered vehicles. To efficiently transfer heat from these heat-generating electronic elements and components to coolers, thermally conductive silicone compositions are becoming indispensable.

[0003] Furthermore, in recent years, the need to mount numerous electronic elements and components within a limited space has led to a wide variety of mounting environments (temperature, angle, etc.). For example, heat-generating electronic elements and components are no longer placed horizontally with cooling plates, and the thermally conductive materials connecting them are often mounted at a certain angle. In such operating environments, thermally conductive silicone adhesives or potting materials are sometimes used, or room-temperature curing thermally conductive silicone rubber compositions are used to prevent the thermally conductive material from sagging and leaking from between the heat-generating and cooling elements (Japanese Patent Publication No. Hei 8-208993, Japanese Patent Publication No. Sho 61-157569, Japanese Patent Publication No. 2004-352947, Japanese Patent No. 3543663, Japanese Patent No. 4255287: Patent Documents 1-5). However, in all cases, complete adhesion is achieved, resulting in the disadvantage of poor reworkability. Furthermore, because the thermally conductive material becomes extremely hard after bonding, repeated stress due to thermal distortion can cause it to detach from the heating element, leading to a sudden increase in thermal resistance, or putting stress on electronic elements and components after hardening.

[0004] To solve the above problems, a condensation-curing type heat dissipation material has been proposed (Japanese Patent No. 5846323: Patent Document 6). By using this technology, a certain degree of reworkability can be ensured even after curing, and it does not drip after curing. Moreover, since it remains in a soft grease-like state even after curing, it can also serve as a stress reliever, and a heat conductive material that is less likely to be inhibited from curing by contaminants can be obtained. However, in the conventional condensation-curing type heat conductive silicone composition, the mixing time of the wetter component and the base polymer component is long, and there is a risk that the ends of the base polymer will partially react with the wetter component, resulting in large variations in hardness and curability.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a condensation-curing type heat conductive silicone composition that cures with moisture at room temperature, has a low hardness of the cured product and is suitable for stress relaxation, and exhibits stable physical properties during production.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that the physical properties of the condensation-curing type thermally conductive silicone composition are stabilized by heating and mixing the wetter component and the filler component in a mixer first and then passing through a step of mixing the base polymer component, the crosslinking agent component, and the catalyst component, and thus have completed the present invention.

[0008] Therefore, the present invention provides the following condensation-curing type thermally conductive silicone composition and a method for producing the same. 1. The following components (A) to (E) (A) An organopolysiloxane having a viscosity at 23°C of 50 mPa·s or more represented by the following general formula (1): 10 to 70 parts by mass, HO-(SiR c , 4 , , 4-c , 4 , 2O) a -H (1) (In the formula, R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups from each other. a is an integer of 20 or more.) (B) The following general formula (2)

Chemical formula

[0009] The condensation-curing type thermally conductive silicone composition of the present invention is particularly suitable as a heat dissipation material for electrical, electronic, and automotive applications because it provides a cured product (silicone rubber) with low hardness and excellent heat resistance after curing, and its physical properties are stable during manufacturing. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. The method for producing the condensation-curing type thermally conductive silicone composition of the present invention uses the following components (A) to (E). Room temperature refers to 23°C ± 15°C, preferably 20 to 25°C.

[0011] [(A) Ingredient: Organopolysiloxane] The organopolysiloxane of component (A) is represented by the following general formula (1). HO-(SiR 1 20) a -H (1) (In the formula, R 1 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R1 The elements may be identical or different. (a is an integer greater than or equal to 20.)

[0012] As shown in formula (1), component (A) is a diorganopolysiloxane with a main chain consisting of repeating diorganosiloxane units, with both ends of the molecular chain sealed by hydroxyl groups (silanol groups) bonded to silicon atoms, a viscosity of 50 mPa·s or more at 23°C, and linear siloxane bonds in the main chain, and acts as the main component (base polymer) of the condensation-curing type thermally conductive silicone composition of the present invention.

[0013] In general formula (1), R 1 This refers to unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and 2-ethylhexyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and hexenyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as benzyl and phenylethyl. Alternatively, these hydrocarbon groups may be partially substituted with halogen atoms such as fluorine, chlorine, or bromine, such as the trifluoropropyl group. 1 The unsubstituted or substituted monovalent hydrocarbon group is preferably one that does not contain an aliphatic unsaturated bond, specifically an alkyl group such as a methyl group, an aryl group such as a phenyl group is preferred, and a methyl group is particularly preferred. 1 These may be the same group or different groups.

[0014] In general formula (1), the main chain consists of bifunctional diorganosiloxane units ((SiR 1 20 2 / 2 )) The number of repetitions (or degree of polymerization) of )) a is an integer of 20 or more, preferably an integer between 50 and 1,000, more preferably an integer between 100 and 800, and particularly preferably an integer between 200 and 700.

[0015] The viscosity of component (A), the organopolysiloxane, at 23°C is 50 mPa·s or higher, preferably in the range of 50 to 50,000 mPa·s, more preferably in the range of 300 to 30,000 mPa·s, and particularly preferably in the range of 500 to 20,000 mPa·s. In the present invention, viscosity can be measured by a rotational viscometer (e.g., BL type, BH type, BS type, cone plate type, etc.) (the same applies hereinafter).

[0016] Furthermore, in the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as the number-average degree of polymerization (or number-average molecular weight) in terms of polystyrene in gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF), etc. as the developing solvent. (A) The organopolysiloxane may be one type or two or more types may be used in combination.

[0017] Component (A) should be used in a range of 10 to 70 parts by mass, preferably in a range of 20 to 60 parts by mass, because if the amount of component (A) is less than 10 parts by mass out of the total 100 parts by mass of components (A) and (B), the resulting composition will not harden, and if it is more than 70 parts by mass, the cured product of the resulting composition will become too hard.

[0018] [(B) Component: Organopolysiloxane with a hydrolyzable group at one end] The component (B) used in the present invention is an organopolysiloxane represented by the following general formula (2). Component (B) is a wetter component that plays an important role in imparting appropriate hardness (softness) to the cured composition. [ka] (In the formula, R 2 R is an unsubstituted or substituted monovalent hydrocarbon group, 3 (where n is an integer between 2 and 100, and b is an integer between 1 and 3.)

[0019] In equation (2) above, R 2 These are independently unsubstituted or substituted monovalent hydrocarbon groups, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. Examples include linear alkyl groups, branched alkyl groups, cyclic alkyl groups (cycloalkyl groups), alkenyl groups, aryl groups, and aralkyl groups. Alternatively, these hydrocarbon groups may be groups in which the hydrogen atoms are partially substituted with halogen atoms such as fluorine, chlorine, or bromine, or with cyano groups, such as halogenated alkyl groups and cyanoalkyl groups. Examples of linear alkyl groups include methyl, ethyl, propyl, hexyl, and octyl groups. Examples of branched alkyl groups include isopropyl, isobutyl, tert-butyl, and 2-ethylhexyl groups. Examples of cyclic alkyl groups include cyclopentyl and cyclohexyl groups. Examples of alkenyl groups include vinyl and allyl groups. Examples of aryl groups include phenyl and tolyl groups. Examples of aralkyl groups include 2-phenylethyl and 2-methyl-2-phenylethyl groups. Examples of alkyl halides include 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, and 2-(heptadecafluorooctyl)ethyl groups. An example of a cyanoalkyl group is the cyanoethyl group. 2 Preferably, these are methyl groups, phenyl groups, and vinyl groups.

[0020] In equation (2) above, R 3 R is independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. 3 The C1 is preferably 1 to 8, and more preferably 1 to 3. Examples of alkyl groups include R 2 Examples of linear alkyl groups, branched alkyl groups, and cyclic alkyl groups are similar to those exemplified above. Examples of alkoxyalkyl groups include methoxyethyl group and methoxypropyl group. Examples of acyl groups include acetyl group and octanoyl group. 3It is preferable that the group is an alkyl group, and more preferably a methyl group or an ethyl group. n is an integer between 2 and 100, preferably between 5 and 80. b is an integer between 1 and 3, preferably 3.

[0021] The viscosity of component (B) at 23°C is preferably 5 to 10,000 mPa·s, and particularly preferably 5 to 5,000 mPa·s. By setting the viscosity above the lower limit, the resulting condensation-curing type thermal conductive silicone composition has suppressed oil bleeding and is less prone to sagging, while setting it below the upper limit results in a composition with excellent coating workability.

[0022] (B) Suitable specific examples of component include the following: [ka] (In the formula, Me represents a methyl group.) (B) Component (B) may be used alone or in combination of two or more components.

[0023] If the amount of component (B) is less than 30 parts by mass out of the total 100 parts by mass of components (A) and (B), the cured product of the resulting composition will be hard and a soft composition cannot be obtained. If it is more than 90 parts by mass, the resulting composition will not harden. Therefore, it should be used in the range of 30 to 90 parts by mass, preferably in the range of 40 to 80 parts by mass.

[0024] [(C) Component: Hydrolyzable organosilane compound and / or its (partial) hydrolysate or (partial) hydrolyzate condensate] Component (C) is at least one of the following: a silane compound other than component (B) having three or more hydrolyzable groups bonded to silicon atoms in one molecule, a (partial) hydrolysate thereof, and a (partial) hydrolyzate condensate thereof, and acts as a crosslinking agent for the composition of the present invention. The silane compound is represented by the following general formula (3). R 4 c SiX 4-c (3) (In the formula, R 4 (where c is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group. c is 0 or 1, preferably 1.)

[0025] In general formula (3), examples of the hydrolyzable group X include ketoxime groups, alkoxy groups, acyloxy groups, and alkenyloxy groups. Specifically, examples include ketoxime groups with 3 to 8 carbon atoms such as dimethylketoxime group, methylethylketoxime group, and methylisobutylketoxime group; alkoxy groups with 1 to 4 carbon atoms, particularly 1 or 2 carbon atoms such as methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group; acyloxy groups with 2 to 4 carbon atoms such as acetoxy group and propionoxy group; and alkenyloxy groups with 2 to 5 carbon atoms such as vinyloxy group, allyloxy group, propenoxy group, isopropenoxy group, and cyclopenta-1-en-1-yl)oxy group. X may be the same group or different groups.

[0026] Furthermore, in general formula (3), the remaining group R bonded to silicon atoms other than the hydrolyzable group 4 The monovalent hydrocarbon group is not particularly limited as long as it is unsubstituted or halogen-substituted, but specifically, examples include unsubstituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkenyl groups such as vinyl groups, and aryl groups such as phenyl groups, and halogen-substituted monovalent hydrocarbon groups such as chloromethyl groups and trifluoropropyl groups, in which some of the hydrogen atoms bonded to the carbon atoms of the unsubstituted monovalent hydrocarbon group are substituted with halogen atoms such as fluorine, chlorine, and bromine. Among these, unsubstituted monovalent hydrocarbon groups are preferred, and methyl, ethyl, vinyl, and phenyl groups are more preferred.

[0027] Specific examples of such (C) components include ketoxime silanes such as tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutylketoxime)silane, and vinyltris(methylethylketoxime)silane; alkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane; methyltriacetoxysilane; and vinyl Examples include acetoxysilanes such as triacetoxysilane and phenyltriacetoxysilane, isopropenoxysilanes such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, and phenyltriisopropenoxysilane, alkenyloxysilanes such as silyl enol ethers such as methyltris[(cyclopenta-1-en-1-yl)oxy]silane, vinyltris[(cyclopenta-1-en-1-yl)oxy]silane, and phenyltris[(cyclopenta-1-en-1-yl)oxy]silane, and (partial) hydrolysates or (partial) hydrolyzates of these silanes, with alkenyloxysilanes being more preferred. These may be used individually or in combination of two or more types.

[0028] The amount of component (C) added is in the range of 1 to 30 parts by mass, preferably 2 to 28 parts by mass, and more preferably 5 to 25 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). If it is less than 1 part by mass, the resulting composition will not harden, and if it is more than 30 parts by mass, the hardening time of the resulting composition may become too long.

[0029] [(D) Component: Non-silicon organic compounds, hydrolyzable organosilane compounds, and partially hydrolyzed condensates thereof, each having at least one guanidine skeleton in one molecule] Component (D) is one or more selected from non-silicon organic compounds, hydrolyzable organosilane compounds, and their partially hydrolyzed condensates (hereinafter, "hydrolyzable organosilane compounds and their partially hydrolyzed condensates" are collectively referred to as organosilicon compounds), which have at least one guanidine skeleton in one molecule, and acts as a curing catalyst (catalytic component) in the present invention, and provides good curability to the composition of the present invention.

[0030] Here, having at least one guanidine skeleton in a molecule means that the compound contains a structure in which one carbon atom is bonded to one nitrogen atom by one double bond and two nitrogen atoms by two single bonds, and this structure is represented by the following general formulas (4) and (5). [ka] (In the formula, R 5 (These are independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group.)

[0031] In the above equations (4) and (5), R 5 R is independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group. Examples of unsubstituted or substituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and octadecyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, aryl groups such as phenyl, tolyl, xylyl, α-,β-naphthyl groups, benzyl, 2-phenylethyl, and 3-phenylpropyl groups, and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as F, Cl, and Br, or cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl groups. 5Preferably, the group is a hydrogen atom, an alkyl group such as a methyl group or ethyl group, a methylol group or a cyano group, and more preferably a hydrogen atom or a methyl group. Furthermore, the number of carbon atoms is preferably 1 to 3.

[0032] Examples of non-silicon organic compounds and hydrolyzable organosilane compounds in component (D) that have at least one guanidine skeleton represented by the above formulas (4) and (5) in one molecule are shown by the following general formulas (4') and (5'). [ka] (In the formula, R 5 This is the same as above, R 6 R is a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, a cyano group, or an alkoxysilane residue. 5 or R 6 If it is a hydrogen atom, it may form a salt by bonding with an inorganic acid.

[0033] In the above equations (4') and (5'), R 6 The residues are a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, a cyano group, or an alkoxysilane residue. Examples of unsubstituted or substituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and octadecyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, aryl groups such as phenyl, tolyl, xylyl, α-,β-naphthyl groups, benzyl, 2-phenylethyl, and 3-phenylpropyl groups, and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as F, Cl, and Br, or cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl groups.

[0034] Furthermore, examples of alkoxysilane residues include the group shown in the following formula. -A-Si(OR') 3-d R" d (In the formula, A is a divalent hydrocarbon group having 1 to 8 carbon atoms, R' and R'' are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and d is 0, 1, or 2.)

[0035] In the above formula, A is a divalent hydrocarbon group having 1 to 8 carbon atoms, preferably a divalent hydrocarbon group having 2 to 4 carbon atoms, and -(CH2) p An alkylene group represented by -(where p is an integer from 1 to 8, preferably an integer from 2 to 4) is preferred. Furthermore, R' and R'' are each independently unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably monovalent hydrocarbon groups having 1 to 8 carbon atoms, and more preferably monovalent hydrocarbon groups having 1 to 4 carbon atoms. Specifically, these include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, and dodecyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, pentenyl, and hexenyl groups; and phenyl and triglycerides. Examples include aryl groups such as xylyl, xylyl, and α- and β-naphthyl groups; aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl groups; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as F, Cl, and Br, or cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl groups, and alkyl groups in which some of the hydrogen atoms of these groups are substituted with lower alkoxy groups such as methoxy and ethoxy groups, such as methoxymethyl, methoxyethyl, ethoxymethyl, and ethoxyethyl groups. Among these, lower alkyl groups having 1 to 4 carbon atoms, such as methyl and ethyl groups, are preferred.

[0036] R 6Preferably, the residue is a hydrogen atom, a methyl group, an alkyl group of an ethyl group, a methylol group, a cyano group, or an alkoxysilane residue, and more preferably a hydrogen atom, a methyl group, or an alkoxysilane residue. Furthermore, the number of carbon atoms is preferably 1 to 12.

[0037] Examples of non-silicon organic compounds having at least one guanidine skeleton of component (D) in one molecule include inorganic guanidines such as guanidine hydrochloride, guanidine carbonate, guanidine nitrate, guanidine sulfate, and guanidine phosphate, and organic guanidines such as aminoguanidine, 1,1,3,3-tetramethylguanidine, n-dodecylguanidine, methylolguanidine, dimethylolguanidine, 1-phenylguanidine, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, triphenylguanidine, 1-benzyl-2,3-dimethylcyanoguanidine, and 2-carbamoyl-1,1,3,3-tetramethylguanidine. Furthermore, specific examples of organosilicon compounds having at least one guanidine skeleton in one molecule include alkoxysilanes such as tetramethylguanidylpropyltrimethoxysilane (also known as 1,1,3,3-tetramethyl-2-[3-(trimethoxysilyl)propyl]guanidine) and N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea, and their hydrolysis condensates (siloxanes). Among these, it is preferable to use organoguanidines, alkoxysilanes, and their hydrolysis condensates, and among these, it is particularly preferable to use alkoxysilanes such as 1,1,3,3-tetramethyl-2-[3-(trimethoxysilyl)propyl]guanidine and N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea, and their hydrolysis condensates.

[0038] (D) The non-silicon organic compound and / or organosilicon compound having at least one guanidine skeleton in one molecule may be one type each, or two or more types may be used in combination.

[0039] The non-silicon organic compound and / or organosilicon compound having at least one guanidine skeleton of component (D) in one molecule is used in an amount of 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, more preferably 0.3 to 6 parts by mass, per 100 parts by mass of the total of components (A) and (B). If the amount is less than the lower limit, the curability of the resulting composition may deteriorate, and if the amount exceeds the upper limit, the odor and shelf life of the resulting composition may deteriorate.

[0040] [(E) Component; Thermally conductive filler] As for the thermally conductive filler of component (E), if the thermal conductivity of the filler is less than 10 W / m·°C, the thermal conductivity of the condensation-curing type thermally conductive silicone composition itself will be reduced. Therefore, a filler with a thermal conductivity of 10 W / m·°C or higher, preferably 15 W / m·°C or higher, should be used. Examples of such thermally conductive fillers include aluminum powder, copper powder, silver powder, nickel powder, gold powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, diamond powder, and carbon powder. Any filler with a thermal conductivity of 10 W / m·℃ or higher is acceptable, and one type or a mixture of two or more types may be used.

[0041] The average particle size of the thermally conductive filler is preferably in the range of 0.1 to 200 μm, and more preferably in the range of 0.1 to 150 μm. A condensation-curing thermally conductive composition obtained with an average particle size above the lower limit exhibits excellent workability, while a composition obtained with an average particle size below the upper limit exhibits excellent uniformity. Furthermore, the shape of the filler can be irregular, spherical, or any other shape. The average particle size can be determined, for example, by the weight-average value (or median diameter) obtained by laser diffraction.

[0042] If component (E) is used in amounts less than 100 parts by mass relative to the total of components (A) and (B) (a total of 100 parts by mass), the desired thermal conductivity cannot be obtained in the cured product of the resulting composition. If it is used in amounts greater than 2,000 parts by mass, the composition will have poor workability. Therefore, it is used in the range of 100 to 2,000 parts by mass, preferably in the range of 500 to 1,800 parts by mass.

[0043] [(F) component; silane coupling agent having a specified functional group other than components (C) and (D), and / or a partially hydrolyzed condensate thereof] The condensation-curing thermally conductive silicone composition of the present invention may further contain, as component (F), a silane compound and / or a partially hydrolyzed condensate thereof having a group (functional group) selected from the group consisting of an amino group, epoxy group, mercapto group, acryloyl group, and methacryloyl group bonded to a silicon atom via a carbon atom, and a hydrolyzable group bonded to a silicon atom. This component is optional and plays a role in enhancing the adhesion between the composition of the present invention and the coated surface.

[0044] The silane compound and its partially hydrolyzed condensate preferably have 1 to 3, more preferably 2 to 3, hydrolyzable groups. If two or more of the above functional groups are present in the silane compound and its partially hydrolyzed condensate, they may be bonded to the silicon atom via different carbon atoms or via the same carbon atom. Examples of hydrolyzable groups include those similar to the hydrolyzable group X in formula (3) of component (C), with alkoxy groups being particularly preferred.

[0045] Specific examples of the above silane compounds include amino group-containing silanes such as 3-aminopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 2-aminoethylaminomethyldimethoxymethylsilane, and 2-aminoethylaminomethyltrimethoxysilane, as well as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, and γ-mercaptopropyl Examples include mercapto group-containing silanes such as captopropylmethyldiethoxysilane, epoxy group-containing silanes such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxyethyltrimethoxysilane, and 3-glycidoxyethyldimethoxymethylsilane, and (meth)acryloyl group-containing silanes such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane, acryloxypropyltrimethoxysilane, and acryloxypropyltriethoxysilane. (F) Component is not limited to one type, but may be used as a mixture of two or more types.

[0046] When incorporating component (F) as described above, the amount to be added is preferably in the range of 0.01 to 30 parts by mass, and more preferably in the range of 0.1 to 20 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). By keeping the amount within this range, an improvement in adhesion due to the inclusion of component (F) can be observed.

[0047] Furthermore, the condensation-curing type thermally conductive silicone composition of the present invention may also contain generally known additives other than components (A) to (E), as long as they do not impair the objectives of the present invention. Examples of additives include polyethers as thixotropic enhancers, silicone oils and isoparaffins as plasticizers, and, if necessary, colorants such as pigments, dyes, and fluorescent whitening agents, as well as physiologically active additives such as antifungal agents, antibacterial agents, and marine organism repellents. In addition, phenyl silicone oil, alkyl-modified silicone oil, and fluorosilicone oil for improving reworkability, silicone resins for improving strength, surface modifiers such as organic liquids incompatible with silicone, and solvents such as toluene, xylene, solvent volatile oils, cyclohexane, methylcyclohexane, and low-boiling point isoparaffins may also be added.

[0048] [Method for producing the composition] The condensation-curing type thermally conductive silicone composition of the present invention comprises the following steps [i] and [ii]. [i] A step of surface treatment of the filler by mixing component (B) and component (E) and then heat-treating them at 100-180°C for 0.5-5 hours, followed by, [ii] A step of mixing components (A), (C), and (D) with the surface-treated filler obtained in step [i].

[0049] In step [i], component (B) and component (E) are mixed until uniform, and then mixed while heating at 100-180°C, preferably 120-160°C, for 0.5-5 hours, preferably 1-4 hours, to wet (surface treat) component (E) with component (B). This step suppresses the reaction between component (A) and component (B), and stabilizes the hardness, curability, and viscosity of the composition. If the heating temperature is lower than 100°C, the wetting may be insufficient and the viscosity may increase, and if it is higher than 180°C, the silicone component may decompose. Also, if the heating time is shorter than 0.5 hours, the wetting may be insufficient and the viscosity may increase, and if it is longer than 5 hours, it may lead to a decrease in production efficiency. Furthermore, in step [i], it is preferable to mix only components (B) and (E) without any other components.

[0050] Next, in step [ii], component (G), which is a heated mixture of component (B) and component (E) obtained by wetting (surface treating) component (E) with component (B) after the wetting step (step [i]), preferably a heated mixture at 100-180°C, is blended with component (A), component (C), component (D), and optionally component (F), and other components, and stirred at room temperature until homogeneous, thereby obtaining the condensation-curing type thermally conductive silicone composition of the present invention. Furthermore, from the standpoint of production efficiency, it is preferable to use the same mixing and stirring device for processes [i] and [ii].

[0051] The condensation-curing type thermally conductive silicone composition of the present invention comprises the above-mentioned components (A), (C), (D), and (G) as a heated mixture of the above-mentioned components (B) and (E), and optionally component (F) and other components.

[0052] Furthermore, the viscosity of the obtained condensation-curing type thermally conductive silicone composition at 23°C is preferably 10 to 150 Pa·s, and particularly preferably 30 to 130 Pa·s.

[0053] The condensation-curing type thermally conductive silicone composition of the present invention cures when exposed to an environment with a temperature of -10 to 50°C and a humidity of 1 to 100% RH. A more preferable curing condition is an environment with a temperature of 10 to 30°C and a humidity of 30 to 80%.

[0054] The condensation-curing type thermally conductive silicone composition of the present invention preferably has a hardness of 10 to 90, and more preferably 20 to 80, at Shore OO after being left at 23±2℃ / 50±5%RH / 7 days (after curing). The above hardness can be measured according to the method specified in ISO 7619-1. Furthermore, the hardness can be achieved by blending 10 to 70 parts by mass of component (A) with 30 to 90 parts by mass of component (B) such that the total of component (A) and (B) is 100 parts by mass.

[0055] Furthermore, the condensation-curing type thermally conductive silicone composition of the present invention preferably has a thermal conductivity of 0.5 W / m·℃ or higher, and more preferably 1.0 W / m·℃ or higher, after being left at 23±2℃ / 50±5%RH / 7 days (after curing). The thermal conductivity can be measured using a hot disk method thermophysical property measuring device. In order to achieve the thermal conductivity within the above range, it can be achieved by adding 100 to 2000 parts by mass of component (E) to a total of 100 parts by mass of components (A) and (B).

[0056] As described above, the condensation-curing type thermally conductive silicone composition obtained in this way has stable physical properties during manufacturing and remains soft after curing. Therefore, when used as a heat dissipation material such as a gap filler, it has excellent reworkability and there is no concern about placing large stresses on electronic components. Furthermore, it also has good heat resistance, so it can be used in a wide range of fields where heat dissipation and heat resistance are required, such as the electrical and electronic fields and the transportation equipment field. [Examples]

[0057] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereto. In order to clarify the advantages of the present invention, specific examples will be provided to demonstrate them. In the following formula, Me represents a methyl group. The viscosity of components (A) and (B) was measured using a BH-type rotational viscometer, and the degree of polymerization was measured by gel permeation chromatography (GPC) analysis.

[0058] First, we prepared the following ingredients. (A) component A-1: Dimethylpolysiloxane with a viscosity of 20,000 mPa·s at 23°C and hydroxyl groups sealed at both ends (a=610 in formula (1) above).

[0059] (B) Component B-1: Organopolysiloxane represented by the following formula (viscosity at 23°C: 30 mPa·s) [ka] B-2: Organopolysiloxane represented by the following formula (viscosity at 23°C: 30 mPa·s) [ka]

[0060] (C) Component C-1: Phenyltriisopropenoxysilane C-2: Vinyltris[(cyclopenta-1-en-1-yl)oxy]silane

[0061] (D) Component D-1: Tetramethylguanidylpropyltrimethoxysilane D-2:N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea

[0062] (E) Component E-1: Alumina powder with an average particle size of 10 μm (thermal conductivity: 27 W / m·℃)

[0063] (F) component The following amino group-containing silanes F-1:3-aminopropyltriethoxysilane

[0064] [Examples 1-4] The compositions of the examples were obtained by mixing components (A) to (F) in the amounts shown in Table 1 as follows. Components (B) and (E) were placed in the amounts shown in Table 1 into a mixing stirrer (5XDMV-R, manufactured by Dalton Co., Ltd.) and degassed and heated and mixed at 150°C for 3 hours (step [i]). After cooling to room temperature, components (A), (C), and (D) were added and degassed and mixed at room temperature until homogeneous. Component (F) was added as needed and degassed and mixed at room temperature until homogeneous (step [ii]). The touch-dry time, viscosity, hardness, and thermal conductivity of the condensation-curing type thermal conductive silicone composition obtained in this way were evaluated by the methods shown below. The results are shown in Table 1.

[0065] [Comparative Examples 1-4] Comparative composition was obtained by mixing components (A) to (F) in the amounts shown in Table 1 as follows. Components (A), (B), and (E) were placed in the amounts shown in Table 1 into a mixing stirrer (5XDMV-R, manufactured by Dalton Co., Ltd.) and degassed and heated and mixed at 150°C for 3 hours. After cooling to room temperature, components (C) and (D) were added and degassed and mixed at room temperature until homogeneous. Component (F) was added as needed and degassed and mixed at room temperature until homogeneous. The touch-dry time, viscosity, hardness, and thermal conductivity of the condensation-curing type thermal conductive silicone composition obtained in this way were evaluated by the methods shown below. The results are shown in Table 1.

[0066] [Evaluation of touch-dry time] The touch-dry time was measured in accordance with the method specified in JIS A 5758.

[0067] [Viscosity evaluation] Viscosity values ​​are shown for 23°C, and measurements were taken using a capillary rheometer (Malvern RH2000).

[0068] [Initial hardness evaluation] The condensation-curing thermally conductive silicone composition obtained above was formed into a 2.0 mm sheet, left to cure at 23±2℃ / 50±5%RH for 7 days, and then its Shore OO hardness was measured according to the method specified in ISO 7619-1.

[0069] [Thermal conductivity evaluation] The condensation-curing type thermally conductive silicone composition obtained above was formed into a 6.0 mm sheet and left to cure at 23±2℃ / 50±5%RH for 7 days. After curing, the thermal conductivity was measured using a hot disk method thermophysical property measurement device TPA-501 manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0070] [Table 1]

[0071] From the results above, it can be seen that the condensation-curing type thermal conductive silicone composition of the example has a shorter touch-dry time and higher hardness compared to the condensation-curing type thermal conductive silicone composition of the comparative example. This is because the reaction between component (A) and component (B) was suppressed, and the cross-linked structure was formed as intended. Furthermore, the viscosity of the comparative example, in which components (A) and (B) were mixed and heat-treated, is higher than that of the example. This is because a portion of component (A) and component (B) reacted to form a cross-linked structure, resulting in increased viscosity. These results indicate that the process of the present invention, which can suppress the reaction between component (A) and component (B), is preferable for the stable production of the product.

Claims

1. The following ingredients (A) to (E) (A) Organopolysiloxane with a viscosity of 50 mPa·s or more at 23°C as shown in the following general formula (1): 10 to 70 parts by mass, HO-(SiR 1 2 O) a -+ (1) (In the formula, R 1 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 (The elements may be identical or different. a is an integer greater than or equal to 20.) (B) General formula (2) 【Chemistry 1】 (In the formula, R 2 R is independently an unsubstituted or substituted monovalent hydrocarbon group. 3 (where n is an integer from 2 to 100, and b is an integer from 1 to 3.) Organopolysiloxanes represented by: 30 to 90 parts by mass, (However, the total amount of component (A) and component (B) is 100 parts by mass.) Silane compounds other than components (C) and (B) that have three or more hydrolyzable groups bonded to silicon atoms represented by the following general formula (3) in one molecule, and / or their (partial) hydrolysates or (partial) hydrolyzed condensates: 1 to 30 parts by mass, R 4 c SiX 4-c (3) (In the formula, R 4 (where is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group; c is 0 or 1.) A curing catalyst consisting of one or more non-silicon-based organic compounds, hydrolyzable organosilane compounds, and their partially hydrolyzed condensates, each having at least one guanidine skeleton represented by the following general formulas (4) and (5) in one molecule, other than components (D) and (C): 0.1 to 10 parts by mass. 【Chemistry 2】 (In the formula, R 5 (These are independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group.) (E) Thermally conductive filler having a thermal conductivity of 10 W / (m·°C) or higher: 100 to 2,000 parts by mass A method for producing a condensation-curing type thermally conductive silicone composition using the following: [i] A step of surface treatment of the filler by mixing component (B) and component (E) and then heat-treating them at 100 to 180°C for 0.5 to 5 hours, then, [ii] A step of mixing components (A), (C), and (D) into the surface-treated filler obtained in step [i]. A method for producing a condensation-curing type thermally conductive silicone composition, characterized by containing [a specific ingredient].

2. A method for producing a condensation-curing type thermally conductive silicone composition according to claim 1, characterized in that the obtained condensation-curing type thermally conductive silicone composition has a Shore OO hardness of 10 to 90 at 23°C after being left for 7 days at 23±2°C / 50±5%RH.

3. A method for producing a condensation-curing type thermally conductive silicone composition according to claim 1, characterized in that the thermal conductivity of the obtained condensation-curing type thermally conductive silicone composition after being left at 23±2℃ / 50±5%RH / 7 days is 0.5 W / m·℃ or higher.

4. A method for producing a condensation-curing type thermally conductive silicone composition according to claim 1, characterized in that in step [ii], the method further includes 0.01 to 30 parts by mass of a silane compound and / or a partially hydrolyzed condensate thereof having a group selected from the group consisting of an amino group, epoxy group, mercapto group, acryloyl group and methacryloyl group bonded to a silicon atom via a carbon atom, and a hydrolyzable group bonded to a silicon atom, with respect to 100 parts by mass of the total of components (A) and (B).

5. (A) Organopolysiloxane with a viscosity of 50 mPa·s or more at 23°C as shown in the following general formula (1): 10 to 70 parts by mass, HO-(SiR 1 2 O) a -+ (1) (In the formula, R 1 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 (The elements may be identical or different. a is an integer greater than or equal to 20.) Silane compounds other than components (C) and (B) that have three or more hydrolyzable groups bonded to silicon atoms represented by the following general formula (3) in one molecule, and / or their (partial) hydrolysates or (partial) hydrolyzed condensates: 1 to 30 parts by mass, R 4 c SiX 4-c (3) (In the formula, R 4 (where is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group; c is 0 or 1.) A curing catalyst consisting of one or more non-silicon-based organic compounds, hydrolyzable organosilane compounds, and their partial hydrolysis condensates, each having at least one guanidine skeleton represented by the following general formulas (4) and (5) in one molecule, other than components (D) and (C): 0.1 to 10 parts by mass 【Transformation 3】 (In the formula, R 5 (These are independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group.) (G) A heated mixture of component (B) and component (E) below. (B) General formula (2) 【Chemistry 4】 (In the formula, R 2 R is independently an unsubstituted or substituted monovalent hydrocarbon group. 3 (where n is an integer from 2 to 100, and b is an integer from 1 to 3.) Organopolysiloxanes represented by: 30 to 90 parts by mass, (However, the total amount of component (A) and component (B) is 100 parts by mass.) (E) Thermally conductive filler having a thermal conductivity of 10 W / (m·°C) or higher: 100 to 2,000 parts by mass A condensation-curing type thermally conductive silicone composition containing [a specific substance].

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