JP4557137B2 - Thermally conductive silicone rubber composition and molded product - Google Patents

Description

  The present invention relates to a thermally conductive silicone rubber composition that can be a cured product that has good handleability and moldability even when containing a large amount of a thermally conductive filler, and that provides good rubber properties and adhesion, and this composition The present invention relates to a molded product obtained by curing a product.

  Conventionally, the characteristics of heat-generating parts such as power transistors and thyristors deteriorate due to the generation of heat, so when installing, heat sinks are installed to dissipate the heat and allow the heat to escape to the metal chassis of the equipment. It has been. At this time, in order to improve electrical insulation and thermal conductivity, a heat radiation insulating sheet in which a heat conductive filler is blended with silicone rubber is used between the heat generating component and the heat sink.

  As this heat insulating material, Japanese Patent Laid-Open No. 47-32400 (Patent Document 1), from 100 parts by weight of synthetic rubber such as silicone rubber, beryllium oxide, aluminum oxide, hydrated aluminum oxide, magnesium oxide, zinc oxide. An insulating composition containing 100 to 800 parts by weight of at least one selected metal oxide is disclosed.

  Further, as a heat dissipation material used in a place where insulation is not required, Japanese Patent Application Laid-Open No. 56-1009009 (Patent Document 2) discloses heat conductivity of addition curing type silicone rubber, silica, silver, gold, silicon and the like. A composition containing 60 to 500 parts by weight of powder is disclosed.

  However, these thermal conductive materials can only be obtained with a thermal conductivity of less than 1.5 W / mK, and the fluidity decreases when a large amount of the thermal conductive filler is filled in order to improve the thermal conductivity. However, there is a problem that the moldability becomes very poor.

  Therefore, as a method for solving this, Japanese Patent Laid-Open No. 1-69661 (Patent Document 3) discloses 10 to 30% by weight of alumina particles having an average particle size of 5 μm or less, and the balance is a single particle having an average particle size of 10 μm or more. And a highly thermally conductive rubber / plastic composition filled with alumina composed of spherical corundum particles having a shape having no cutting edge. JP-A-4-328163 (Patent Document 4) discloses a gum-like organopolysiloxane having an average degree of polymerization of 6,000 to 12,000 and an oil-like organopolysiloxane having an average degree of polymerization of 200 to 2,000. A thermally conductive silicone rubber composition comprising 500 to 1,200 parts by weight of spherical aluminum oxide powder per 100 parts by weight of the base polymer component in combination is disclosed.

  However, even if these methods are used, if an attempt is made to fill 1,000 parts by weight or more of aluminum oxide powder (70% by volume or more of aluminum oxide) per 100 parts by weight of the base polymer component, the combination of particles and the viscosity adjustment of the silicone base However, there was a limit to the improvement of molding processability.

  Therefore, as a means for solving the improvement in molding processability, Japanese Patent Application Laid-Open No. 2000-256558 (Patent Document 5) discloses a heat containing 0.1 to 50% by volume of hydrolyzable group-containing methylpolysiloxane as a wetter. A conductive silicone rubber composition is disclosed. By this method, the moldability of the heat conductive silicone rubber composition was greatly improved. However, this method also has a problem that the physical properties (strength) and adhesiveness of the rubber are lowered when the addition ratio of the wetter is increased in order to realize further high thermal conductivity.

JP 47-32400 A JP-A-56-100849 JP-A-1-69661 JP-A-4-328163 JP 2000-256558 A

  The present invention has been made in view of the above circumstances, and even if it contains a large amount of a heat conductive filler in order to obtain a high heat conductive silicone rubber, it has good handleability and moldability, and good rubber properties and adhesiveness. It is an object of the present invention to provide a thermally conductive silicone rubber composition that can be a cured product that provides the above and a molded product obtained by curing the composition.

  As a result of intensive studies to achieve the above object, the present inventor has (A) (i) two or more silicon atom-bonded alkenyl groups and (ii) one or more hydrolyzable silyl groups in one molecule. Even if the thermally conductive silicone rubber composition containing the organopolysiloxane having (B) the curing agent and (C) the thermally conductive filler contains a large amount of the thermally conductive filler, the handleability and moldability are high. The present inventors have found that the present invention can be a highly heat-conductive silicone rubber that provides good rubber properties and adhesiveness, and has led to the present invention.

（式中、ｔ’は１〜２０の整数、ｕ’は５以上９９未満の整数、ｖ’は５〜４００の整数であり、ｔ’＋ｕ’の和は６以上１００未満である。）
で表される構造のオルガノポリシロキサン、
（Ｂ）一分子中に平均２個以上のケイ素原子結合水素原子を含有するオルガノハイドロジェンポリシロキサンと白金系触媒からなる硬化剤、
（Ｃ）熱伝導性充填剤
を含有し、（Ａ）成分の添加量が（Ｃ）成分１００質量部に対して０．１〜３０質量部であり、（Ｂ）成分のオルガノハイドロジェンポリシロキサンの含有量が、全成分中の総ケイ素原子結合アルケニル基１モルに対してケイ素原子結合水素原子が０．１〜６．０モルとなる量であり、白金系触媒の含有量が、（Ａ）成分と（Ｂ）成分のオルガノハイドロジェンポリシロキサンの合計質量に対して白金系触媒が質量単位で０．０１〜１，０００ｐｐｍとなる量であり、（Ｃ）成分の含有量が、（Ｃ）成分の質量が全成分の総質量の７５〜９８質量％を占める量であることを特徴とする熱伝導性シリコーンゴム組成物。
［請求項２］
式（ｉｉ）において、ｕ’が５〜９４であって、ｔ’＋ｕ’の和が６〜９５である請求項１記載の熱伝導性シリコーンゴム組成物。
［請求項３］
更に、（Ｄ）２５℃における粘度が５０〜１００，０００ｍＰａ・ｓであり、一分子中に平均２〜２０個のケイ素原子結合アルケニル基を含有するオルガノポリシロキサン、及び／又は（Ｅ）下記式（ＩＶ）で表される構造のオルガノポリシロキサンを含み、前記（Ｄ）成分及び（Ｅ）成分の合計含有量が、（Ｃ）成分１００質量部に対して０．１〜２０質量部である請求項１又は２記載の熱伝導性シリコーンゴム組成物。

（式中、Ｂはメチル基、アルケニル基又は−Ｚ−ＳｉＲ² ₃であり、Ｒ² は炭素原子数１〜４のアルコキシ基、アルケニルオキシ基又はアシロキシ基であり、Ｚは酸素原子又は炭素原子数２〜１０の二価炭化水素基であり、ｗは５〜３００の整数である。）
［請求項４］
前記（Ｅ）成分の含有量が、（Ｃ）成分１００質量部に対して０．１〜１０質量部であることを特徴とする請求項３記載の熱伝導性シリコーンゴム組成物。
［請求項５］
（Ｃ）成分の熱伝導性充填剤が、無機粉末及び／又は金属粉末であることを特徴とする請求項１〜４のいずれか１項に記載の熱伝導性シリコーンゴム組成物。
［請求項６］
前記無機粉末が、酸化アルミニウム、酸化亜鉛、酸化ケイ素、炭化ケイ素、窒化ケイ素、酸化マグネシウム、窒化アルミニウム、窒化ホウ素及びグラファイトからなる群から選ばれる少なくとも１種の無機粉末であり、また、前記金属粉末が、アルミニウム、銅、銀、金、ニッケル、鉄及びステンレスからなる群から選ばれる少なくとも１種の金属粉末であることを特徴とする請求項５記載の熱伝導性シリコーンゴム組成物。
［請求項７］
請求項１〜６のいずれか１項に記載の熱伝導性シリコーンゴム組成物を硬化させて得られる成型品。
［請求項８］
熱伝導率が１．５Ｗ／ｍＫ以上であることを特徴とする請求項７記載の成型品。 Accordingly, the present invention provides the following thermally conductive silicone rubber composition and molded article.
[Claim 1]
(A) The following formula (ii) having (i) two or more silicon atom-bonded alkenyl groups and (ii) one or more hydrolyzable silyl groups in one molecule

(In the formula, t ′ is an integer of 1 to 20, u ′ is an integer of 5 or more and less than 99, v ′ is an integer of 5 to 400, and the sum of t ′ + u ′ is 6 or more and less than 100.)
An organopolysiloxane having a structure represented by :
(B) a curing agent comprising an organohydrogenpolysiloxane containing an average of two or more silicon-bonded hydrogen atoms in one molecule and a platinum catalyst ,
( C) containing a thermally conductive filler, ( A) component addition amount is 0.1 to 30 parts by mass with respect to 100 parts by mass of (C) component, and (B) component organohydrogenpolysiloxane The amount of silicon-bonded hydrogen atoms is 0.1 to 6.0 moles per mole of total silicon-bonded alkenyl groups in all components, and the platinum-based catalyst content is (A ) Component and (B) the total mass of the organohydrogenpolysiloxane of the component, the platinum-based catalyst is in an amount of 0.01 to 1,000 ppm by mass unit, and the content of (C) component is (C The heat conductive silicone rubber composition is characterized in that the mass of the component occupies 75 to 98 mass% of the total mass of all components .
[Claim 2]
In formula (ii), 'a is 5~94, t' u + u sum 6-9 5 a is claim 1 thermally conductive silicone rubber composition according to '.
[Claim 3 ]
Furthermore, (D) an organopolysiloxane having a viscosity at 25 ° C. of 50 to 100,000 mPa · s and containing an average of 2 to 20 silicon-bonded alkenyl groups in one molecule, and / or (E) look-containing organopolysiloxane having a structure represented by (IV), the total content of the component (D) and (E) component, 0.1 to 20 parts by weight per 100 parts by weight component (C) The heat conductive silicone rubber composition according to claim 1 or 2 .

(In the formula, B is a methyl group, an alkenyl group or —Z—SiR ² ₃ , R ² is an alkoxy group having 1 to 4 carbon atoms, an alkenyloxy group or an acyloxy group, and Z is an oxygen atom or a carbon atom) ( It is a divalent hydrocarbon group of 2 to 10 and w is an integer of 5 to 300.)
[Claim 4 ]
The heat conductive silicone rubber composition according to claim 3, wherein the content of the component (E) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (C).
[Claim 5 ]
(C) a thermally conductive filler component, inorganic powders and / or thermally conductive silicone rubber composition according to any one of claims 1 to 4, characterized in that a metal powder.
[Claim 6 ]
The inorganic powder is at least one inorganic powder selected from the group consisting of aluminum oxide, zinc oxide, silicon oxide, silicon carbide, silicon nitride, magnesium oxide, aluminum nitride, boron nitride, and graphite, and the metal powder 6. The thermally conductive silicone rubber composition according to claim 5 , wherein is at least one metal powder selected from the group consisting of aluminum, copper, silver, gold, nickel, iron and stainless steel.
[Claim 7 ]
A molded product obtained by curing the thermally conductive silicone rubber composition according to any one of claims 1 to 6 .
[Claim 8 ]
The molded article according to claim 7, wherein the thermal conductivity is 1.5 W / mK or more.

  The thermally conductive silicone rubber composition of the present invention has good handleability and moldability even if it contains a large amount of a thermally conductive filler in order to achieve high thermal conductivity, and has good rubber properties and adhesiveness. It can be a cured product to be given.

The thermally conductive silicone rubber composition of the present invention will be described in detail.
(I) 2 or more, preferably 2 to 20, more preferably 2 to 10 silicon atom-bonded alkenyl groups and (ii) 1 or more, preferably 1 to 10 in one molecule of component (A) More preferably, the organopolysiloxane having 1 to 6 hydrolyzable silyl groups is the main component (base polymer) of the present composition, and a large amount of the thermally conductive filler of the component (C). Even if it mix | blends, it is a component which provides the characteristic of this composition that it can become a hardened | cured material with favorable handleability and moldability, and favorable rubber | gum physical property and adhesiveness. The structure of the component (A) is preferably a structure represented by the following general formula (I).

（式中、Ｒは同一又は異種の置換又は非置換の一価炭化水素基であり、Ｒ¹は炭素原子数１〜４の一価炭化水素基であり、Ｒ²は炭素原子数１〜４のアルコキシ基、アルケニルオキシ基又はアシロキシ基であり、Ｚは酸素原子又は炭素原子数２〜１０の二価炭化水素基である。ｒは０，１又は２であり、ｋ，ｍ，ｎ，ｐ，ｑは各々、ｋ＝５以上１００未満の整数、ｍ＝０〜２０の整数、ｎ＝０〜２０の整数、ｐ＝５〜４００の整数、ｑ＝０〜２０の整数であり、ｋ＋ｍ＋ｎの和は５以上１００未満である。また、Ａ¹，Ａ²及びＡ³は、それぞれＲ、又は−Ｚ−Ｓｉ（Ｒ¹ _r）Ｒ² _(3-r)（Ｒ¹，Ｒ²，ｒ及びＺは前記と同様である。）で示される基である。但し、上記構造において、一分子中に少なくとも２個、好ましくは２〜２０個、より好ましくは２〜１０個のアルケニル基と、少なくとも１個、好ましくは１〜１０個、より好ましくは１〜６個の−Ｚ−Ｓｉ（Ｒ¹ _r）Ｒ² _(3-r)基を含有するものである。）

Wherein R is the same or different substituted or unsubstituted monovalent hydrocarbon group, R ¹ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and R ² is 1 to 4 carbon atoms. An alkoxy group, an alkenyloxy group, or an acyloxy group, Z is an oxygen atom or a divalent hydrocarbon group having 2 to 10 carbon atoms, r is 0, 1 or 2, and k, m, n, p , Q are each an integer of k = 5 or more and less than 100 , an integer of m = 0-20, an integer of n = 0-20, an integer of p = 5-400, an integer of q = 0-20, and k + m + n The sum is 5 or more and less than 100. A ¹ , A ² and A ³ are each R, or —Z—Si (R ¹ _r ) R ² _(3-r) (R ¹ , R ² , r and Z is the same as defined above.) However, in the above structure, at least 2, preferably 2 to 20, more preferably in the molecule. Or 2-10 alkenyl groups and at least 1, preferably 1-10, more preferably 1-6 —Z—Si (R ¹ _r ) R ² _(3-r) groups. )

  Here, R is preferably the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms. Specific examples of such monovalent hydrocarbon groups include R. Is a saturated hydrocarbon group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a hexyl group, or a cycloalkyl group such as a cyclohexyl group, a phenyl group, a tolyl group, or a xylyl group. Group, aryl group such as naphthyl group, aralkyl group such as benzyl group and phenylethyl group, unsaturated hydrocarbon group such as alkenyl group such as vinyl group, allyl group, propenyl group, isopropenyl group and butenyl group, 3, 3 Halogen-substituted hydrocarbon groups such as 1,3-trifluoropropyl group, cyano-substituted hydrocarbon groups, and the like. A Le group.

Examples of R ¹ include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl groups. Examples of R ² include methoxy and ethoxy. Group, n-propoxy group, isopropoxy group, n-butoxy group, acetoxy group, vinyloxy group, allyloxy group, propenoxy group, isopropenoxy group and the like. Examples of Z include oxygen atoms and the following alkylene groups usually having 2 to 6 carbon atoms as divalent hydrocarbon groups.
_{-CH 2 CH 2 -, - CH} 2 CH 2 CH 2 -,
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 2 -, - CH 2 CH (CH 3) CH 2 -

r is preferably 0 or 1, particularly preferably 0, k is preferably an integer of 5 to 95 , m is preferably an integer of 0 to 10, n is preferably an integer of 0 to 10, and p is preferably 5 200 integer, q is preferably from 0 to an integer of, and the sum of k + m + n is good Mashiku is 5-95, the effect is sufficiently exhibited to reduce the viscosity of the composition by the sum of k + m + n is less than 5 May not be. The number of silicon atoms involved in the siloxane (Si—O—Si) structure in the molecule is preferably 5 to 410, preferably 5 to 195, and more preferably about 5 to 120.

（式中、Ｒ²、Ｚは前記のとおりであり、ｓは０〜２０の整数、ｔは０〜２０の整数、ｕは５以上１００未満の整数、ｖは５〜４００の整数であり、ｓ＋ｔ＋ｕの和は５以上１００未満である。また、Ｂは各々独立にメチル基、アルケニル基又は−Ｚ−ＳｉＲ² ₃であるが、上記構造において、アルケニル基は２個以上、好ましくは２〜２０個、より好ましくは２〜１０個存在する。） In the present invention, in order to further improve the effect of lowering the viscosity and plasticity of the composition, a trifunctional hydrolyzable silyl group-containing organopolysiloxane represented by the following general formula (II) is used. It is preferable to use it.

(Wherein R ² and Z are as described above, s is an integer of 0 to 20, t is an integer of 0 to 20, u is an integer of 5 or more and less than 100 , and v is an integer of 5 to 400, The sum of s + t + u is 5 or more and less than 100. Further , each B is independently a methyl group, an alkenyl group, or —Z—SiR ² ₃ , but in the above structure, the number of alkenyl groups is 2 or more, preferably 2 to 20 And more preferably 2-10.)

（式中、Ｒ ² 、Ｚは前記のとおり、ｓは１〜２０の整数であり、ｕは５以上９９未満の整数、ｓ＋ｕの和は６以上１００未満、より好ましくは６〜９５である。なお、上記構造において、アルケニル基は２個以上、好ましくは２〜２０個、より好ましくは２〜１０個存在するものである。） Furthermore, considering the ease of synthesis, it is more preferably a hydrolyzable group-containing diorganopolysiloxane represented by the following general formula ( i ).

( Wherein, R ² and Z are as described above , s is an integer of 1 to 20 , u is an integer of 5 or more and less than 99 , and the sum of s + u is 6 or more and less than 100 , more preferably 6 to 95. In the above structure, there are 2 or more, preferably 2 to 20, more preferably 2 to 10 alkenyl groups.)

（式中、ｓ’は２〜２０、好ましくは２〜１０の整数、ｕ’は５以上９８未満、好ましくは５〜９３の整数、ｓ’＋ｕ’の和は７以上１００未満、より好ましくは１０〜９５である。）

(In the formula, s ′ is an integer of 2 to 20, preferably 2 to 10, u ′ is 5 or more and less than 98 , preferably an integer of 5 to 93 , and the sum of s ′ + u ′ is 7 or more and less than 100 , more preferably 10 to 95.)

（式中、ｔ’は１〜２０、好ましくは１〜１０の整数、ｕ’は５以上９９未満、好ましくは５〜９４の整数、ｖ’は５〜４００、好ましくは５〜２００の整数であり、ｔ’＋ｕ’の和は６以上１００未満、より好ましくは１０〜９５である。）

(In the formula, t ′ is an integer of 1 to 20, preferably 1 to 10, u ′ is 5 or more and less than 99 , preferably an integer of 5 to 94 , and v ′ is an integer of 5 to 400, preferably 5 to 200. And the sum of t ′ + u ′ is 6 or more and less than 100 , more preferably 10 to 95.)

（式中、ｍ’は１〜２０、好ましくは１〜１０の整数、ｓ’は２〜２０、好ましくは２〜１０の整数、ｕ’は５以上９７未満、好ましくは５〜９２の整数であり、ｍ’＋ｓ’＋ｕ’の和は８以上１００未満、より好ましくは１０〜９５である。）

(In the formula, m ′ is an integer of 1 to 20, preferably 1 to 10, s ′ is an integer of 2 to 20, preferably 2 to 10, u ′ is an integer of 5 to less than 97 , preferably an integer of 5 to 92 . And the sum of m ′ + s ′ + u ′ is 8 or more and less than 100 , more preferably 10 to 95.)

（式中、ｓ’は１〜２０、好ましくは１〜１０の整数、ｕ’は６以上９９未満、好ましくは６〜９４の整数、ｓ’＋ｕ’の和は７以上１００未満、より好ましくは１０〜９５である。）

(In the formula, s ′ is an integer of 1 to 20, preferably 1 to 10, u ′ is 6 or more and less than 99 , preferably 6 to 94 , and the sum of s ′ + u ′ is 7 or more and less than 100 , more preferably 10 to 95.)

（式中、ｓ’は２〜２０、好ましくは２〜１０の整数、ｕ’は５以上９８未満、好ましくは５〜９３の整数、ｓ’＋ｕ’の和は７以上１００未満、より好ましくは１０〜９５である。）

(In the formula, s ′ is an integer of 2 to 20, preferably 2 to 10, u ′ is 5 or more and less than 98 , preferably an integer of 5 to 93 , and the sum of s ′ + u ′ is 7 or more and less than 100 , more preferably 10 to 95.)

  The addition amount of the component (A) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the component (C). 1 to 10 parts by mass. When the content of the component (A) is less than the lower limit of the above range, the moldability of the resulting silicone rubber composition may be deteriorated. On the other hand, when the upper limit of the above range is exceeded, (C) in the composition There is a possibility that the content ratio of the components is reduced and the thermal conductivity is lowered.

  The curing agent of component (B) is preferably composed of an organopolysiloxane containing two or more silicon-bonded hydrogen atoms (that is, SiH groups) on average in one molecule and a platinum-based catalyst.

There are no particular restrictions on the molecular structure of the organopolysiloxane (organohydrogenpolysiloxane) containing silicon-bonded hydrogen atoms, and conventionally produced, for example, linear, cyclic, branched, and three-dimensional network structures Various kinds of materials such as, but can be used, it is necessary to have an average of two or more hydrogen atoms (SiH group) bonded to silicon atoms in one molecule, preferably 2 to 200, more preferably 3 It is desirable to have 100. As such an organohydrogenpolysiloxane, those represented by the following average composition formula (1) are used.
R ⁴ _c H _d SiO _{(4-cd) / 2} (1)

In the above formula (1), R ⁴ except the aliphatic unsaturated bond, preferably having 1 to 10 carbon atoms, an unsubstituted or substituted monovalent hydrocarbon group, as the R ⁴ is (A And the same as those exemplified as the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom excluding the alkenyl group described above, preferably an alkyl group or an aryl group, more preferably A methyl group and a phenyl group; C is 0.7 to 2.1, d is 0.001 to 1.0, and c + d is a positive number satisfying 0.8 to 3.0. Preferably, c is 1.0 to 1.0. 2.0 and d are 0.01 to 1.0, and c + d is 1.5 to 2.5.

  The SiH group contained in at least 2, preferably 3 or more in one molecule may be located at either the molecular chain end or in the middle of the molecular chain, or may be located at both of them. The number of silicon atoms in one molecule (or the degree of polymerization) is usually 2 to 300, preferably about 4 to 150, and in the present invention, the viscosity at 25 ° C. is 1 to 100, The liquid is used at room temperature (25 ° C.) of about 000 mPa · s, preferably about 1 to 5,000 mPa · s.

Specific examples of the organohydrogenpolysiloxane of the formula (1) include 1,1,3,3-tetramethyldisiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, Both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, Both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, Both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, Both ends dimethylhydrogensiloxy group-blocked dimethyl Siloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group blocked Methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group blocked Chill hydrogen siloxane, diphenylsiloxane-dimethylsiloxane copolymers, both end dimethylhydrogensiloxy group-blocked methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer, and (CH _{3) 2} HSiO _1/2 units (CH ₃ ) A copolymer comprising ₃ SiO _1/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units, (CH ₃ ) ₂ HSiO _1/2 units, HSiO _3/2 units, and (C ₆ H ₅ ) _{And a} copolymer composed of ₃ SiO _1/2 units.

  The organohydrogenpolysiloxane (B) can be obtained by a known production method. As a general production method, for example, octamethylcyclotetrasiloxane and / or tetramethylcyclodisiloxane and hexamethyldisiloxane which can be a terminal group or 1,1′-dihydro-2,2 ′, 3,3 ′ A compound containing a tetramethyldisiloxane unit can be easily obtained by equilibrating at a temperature of about −10 to + 40 ° C. in the presence of a catalyst such as sulfuric acid, trifluoromethanesulfonic acid or methanesulfonic acid.

  The content of such silicon atom-bonded hydrogen atom-containing organopolysiloxane is such that the silicon atom-bonded hydrogen atom in this component is 0.1 to 6.0 with respect to 1 mol of the total silicon atom-bonded alkenyl group in all components. It is preferable that the amount is mol, particularly 0.5 to 3.0 mol. When the content of this component is less than the lower limit of the above range, the resulting silicone rubber composition may not be sufficiently cured, whereas when the upper limit of the above range is exceeded, the resulting silicone rubber composition is obtained. There is a risk that the physical properties of the rubber will deteriorate.

  The platinum-based catalyst is a catalyst for accelerating the curing of the present composition. For example, chloroplatinic acid, chloroplatinic alcohol solution, platinum olefin complex, platinum alkenylsiloxane complex, platinum carbonyl complex, etc. Can be mentioned.

  The content of the platinum-based catalyst may be an effective amount as a catalyst and is not particularly limited. For example, the organohydrogenpolysiloxane (or the component (A), the component (A) and the component (B), The total amount of the (B) component organohydrogenpolysiloxane, the (D) component and the (E) component described later) is an amount such that the platinum catalyst is in a mass unit of 0.01 to 1,000 ppm, The amount is preferably 0.05 to 500 ppm, particularly preferably 0.1 to 500 ppm. If the content of the platinum-based catalyst is less than the lower limit of the above range, the resulting silicone rubber composition may not be sufficiently cured. On the other hand, even if an amount exceeding the upper limit of the above range is blended, the resulting silicone The curing rate of the rubber composition may not be improved.

  The thermally conductive filler of component (C) is preferably an inorganic powder and / or metal powder having thermal conductivity, specifically, aluminum oxide, zinc oxide, silicon oxide, silicon carbide, silicon nitride, Use one or more inorganic powders selected from magnesium oxide, aluminum nitride, boron nitride, graphite, or one or more metal powders selected from aluminum, copper, silver, gold, nickel, iron, stainless steel, etc. It is also possible to use various powders in combination.

(C) Although it does not specifically limit as an average particle diameter of component, Preferably it is 50 micrometers or less, Usually 0.1-50 micrometers, More preferably, it is 0.2-30 micrometers, More preferably, it is 0.2-20 micrometers. When the average particle size exceeds 50 μm, the dispersibility may be deteriorated. In the case of a liquid silicone rubber, the heat conductive filler may be precipitated if left as it is. The average particle diameter can be determined, for example, as a cumulative weight average value (D ₅₀ ) or a median diameter in particle size distribution measurement by a laser light diffraction method. The shape of the heat conductive filler is preferably close to a rounded sphere. As the shape is rounder, the increase in viscosity can be suppressed even when the filling is high. Examples of such spherical heat conductive fillers include spherical alumina AS series manufactured by Showa Denko KK, and high purity spherical alumina AO series manufactured by Admatechs Co., Ltd. Furthermore, combining a heat conductive filler powder with a large particle size and a heat conductive filler powder with a small particle size in a ratio according to the close-packed packing theoretical distribution curve improves packing efficiency, lowers viscosity, and increases heat conductivity. Therefore, it is preferable.

  The content of the component (C) is preferably such that the mass of the component (C) occupies 75 to 98% by mass of the total mass of all components, more preferably 80 to 97% by mass. More preferably, the amount occupies 85 to 97% by mass. If the content of the component (C) is less than the lower limit of the above range, the resulting silicone rubber may have insufficient thermal conductivity, whereas if it exceeds the upper limit of the above range, the resulting silicone rubber composition will be obtained. Is difficult, the viscosity of the composition becomes high, and the moldability may be deteriorated.

In the present invention, as the component (D), an organopolysiloxane having a viscosity at 25 ° C. of 50 to 100,000 mPa · s and containing an average of 0.1 or more silicon-bonded alkenyl groups in one molecule is used. It is preferable to contain. This organopolysiloxane can be added for the purpose of improving the rubber properties of the composition. This one mean to twenty in a molecule is preferably organopolysiloxane more preferably having an average from 2 to 10 silicon-bonded alkenyl groups per molecule, the silicon-bonded alkenyl in each molecule Even if the average value of the group exceeds the upper limit of the above range and is less than the lower limit, the rubber physical properties of the resulting silicone rubber composition may be deteriorated.

  Examples of the silicon atom-bonded alkenyl group as component (D) include a vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, and the like, and a vinyl group is preferable. Examples of the silicon-bonded organic group other than the alkenyl group of this component include, for example, an alkyl group such as a methyl group, an ethyl group, and a propyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a phenyl group, a tolyl group, and a xylyl group. An aryl group such as a group, or a halogenated hydrocarbon group in which these hydrogen atoms are partially substituted with a chlorine atom, a fluorine atom, or the like is exemplified, preferably an alkyl group or an aryl group, more preferably A methyl group and a phenyl group;

  In addition, it is preferable that content of this alkenyl group shall be 0.01-20 mol% of all the organic groups couple | bonded with the silicon atom in 1 molecule, especially 0.1-10 mol%. In addition, the alkenyl group may be bonded to the silicon atom at the end of the molecular chain, may be bonded to the silicon atom in the middle of the molecular chain, or may be bonded to the both, the curing rate of the composition, From the viewpoint of the physical properties of the cured product, it is preferable that it contains at least a silicon atom at the molecular chain terminal, particularly an alkenyl group bonded to the silicon atom at both molecular chain terminals.

  Moreover, the viscosity at 25 degreeC of (D) component is 50-100,000 mPa * s, Preferably it is 100-50,000 mPa * s. When the viscosity at 25 ° C. is less than the lower limit of the above range, the physical properties of the resulting silicone rubber may be significantly reduced. On the other hand, when the viscosity exceeds the upper limit of the above range, the resulting silicone rubber composition There is a risk that handling will be significantly reduced. The molecular structure of the component (D) is not particularly limited. For example, the main chain is composed of repeating diorganosiloxane units, and both ends of the molecular chain are blocked with a triorganosiloxy group. , A straight chain having a partial branch and a dendritic structure (three-dimensional network structure) are preferable, and a straight chain and a straight chain having a partial branch are preferable. The component (D) is a single polymer having these molecular structures, a copolymer comprising these molecular structures, or a mixture of these polymers.

（式中、Ｂ及びＲ²は前記のとおりであり、ｗは５〜３００、好ましくは５〜２００、より好ましくは５〜１００、更に好ましくは５〜９５の整数である。） The component (E) is a component that, like the component (A), can maintain good handleability and moldability when it contains a large amount of a thermally conductive filler and can be blended as necessary. A compound containing 1 or less alkenyl group directly bonded to a silicon atom in a molecule represented by the following general formula (IV).

(In the formula, B and R ² are as described above, and w is an integer of 5 to 300, preferably 5 to 200, more preferably 5 to 100, and still more preferably 5 to 95.)

（全てのｗは、前記のとおりである。） Although the typical example of the hydrolyzable silyl group containing dimethylpolysiloxane of (E) component is shown below, this component is not limited to this.

(All w are as described above.)

  The total content of the component (D) and the component (E) is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (C). Especially preferably, it is 0.3-10 mass parts. Moreover, as content of (E) component independent, Preferably it is 0.1-10 mass parts with respect to 100 mass parts of (C) component, More preferably, it is 0.3-10 mass parts, Especially preferably. Is 0.3 to 5 parts by mass. When the total content of the component (D) and the component (E) is less than the lower limit of the above range, there may be no effect on the properties of the resulting silicone rubber composition, whereas when the total content exceeds the upper limit of the above range. When realizing high thermal conductivity, the addition ratio of the component (A) in the composition automatically decreases, so the handling properties of the resulting composition deteriorate (when the component (D) is large) and rubber properties There is a case where a decrease in value and a bleed phenomenon (when the component (E) is large) are caused.

  In addition, as a preparation method of the silicone rubber composition of this invention, it is preferable to process the surface of the said (C) component previously with (A) component and / or (E) component. Here, as a method of treating the surface of the component (C) with the component (A) and / or the component (E), for example, the component (C) and the component (A) and / or the component (E) are mixed. , A method of treating the surface of the component (C) with the component (A) and / or the component (E) in advance, and after mixing the component (D) and the component (C), the component (A) and / or the component (E) And the surface of the component (C) in the component (D) is treated with the component (A) and / or the component (E). At this time, it is preferable to knead while heating at a temperature of 80 ° C. or higher with a mixer such as a planetary mixer, a kneader, or a Shinagawa mixer. Even if the temperature is not applied, the composition can be reduced in viscosity and plasticized by kneading for a long time, but heating is necessary to shorten the manufacturing process and reduce the load on the mixer during compounding. It is preferable to promote. In the composition thus obtained, the component (A) and / or the component (E) are in a state of treating the surface of the component (C). Alternatively, the component (E) may be contained free from the component (C).

  Further, as other optional additives, for the purpose of adjusting the curing speed and storage stability of the composition, for example, vinyl group-containing organopolysiloxane such as methylvinylcyclotetrasiloxane, triallyl isocyanurate, acetylene alcohol and siloxane thereof. A modified product may be contained. In addition, the present composition has a heat resistance improver such as a silicone resin, reinforcing silica, a colorant, iron oxide, cerium oxide, a flame retardant, a plasticizer, and adhesion imparting unless the purpose of the present invention is impaired. An agent may be contained.

The method for curing the present composition is not limited, and examples thereof include a method in which the present composition is molded and then allowed to stand at room temperature, and a method in which the composition is molded and then heated to 50 to 200 ° C. Further, the properties of the silicone rubber obtained in this way are not limited, and the silicone rubber is from a hard rubber shape to a low hardness rubber shape, that is, a gel shape.
The molded product thus obtained preferably has a thermal conductivity of 1.5 W / mK or more, particularly 1.5 to 10 W / mK.

The heat conductive silicone rubber composition of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the viscosity is a value measured by a rotational viscometer at 25 ° C., and the average particle diameter is a weight average value (D ₅₀ ) in particle size distribution measurement by a laser light diffraction method.

[Examples 1-2 , Reference Examples 1-6 , Comparative Examples 1-4]
The components shown below were blended according to the composition (parts by mass) shown in Tables 1 and 2, and heat conductive silicone rubber compositions of Examples, Reference Examples and Comparative Examples were prepared.
First, after adding the component (A), the component (C), the component (D) and the component (E), the mixture is kneaded for 10 minutes at room temperature using a Shinagawa mixer, and then heated to 150 ° C. and heated. Kneading for 1 hour. After leaving the obtained base to 40 ° C. or lower, b-2 in the component (B) is uniformly mixed, then the component (F) is added and mixed, and finally b- in the component (B) is added. 1 was uniformly mixed to prepare a heat conductive silicone rubber composition.

(A) Component component a-1:

Component a-2:

Component a-3:

Component a-4:

(B) Component component b-1: (CH ₃ ) ₃ SiO [SiH (CH ₃ ) O] _{8 having} a viscosity at 25 ° C. of 5 mPa · s.
Organohydrogenpolysiloxane represented by Si (CH ₃ ) ₃ (containing SiH)
(Amount 0.01451 mol / g)
Component b-2: Vinylsiloxane complex of chloroplatinic acid (platinum content 1%)

(C) Component component c-1: spherical aluminum oxide powder having an average particle size of 10 μm (Admafine AO-41
R, product name, manufactured by Admatechs)
Component c-2: Spherical aluminum oxide powder having an average particle size of 0.7 μm (Admafine AO-5
02, trade name, manufactured by Admatechs)

(D) Component d: Organopolysiloxane having both ends sealed with dimethylvinylsiloxy groups having a viscosity at 25 ° C. of 600 mPa · s

(E) Component component e-1:

Component e-2:

(F) component component f-1: triallyl isocyanurate component f-2: ethynylcyclohexanol / 50% toluene solution

  Using these silicone rubber compositions, the flowability is measured by the method shown below, and cured under the conditions of 120 ° C. × 1 hour, and the hardness, thermal conductivity, Tensile shear strength and shear bond strength were measured. The measurement results are shown in Tables 1 and 2. These characteristics are values measured at 25 ° C.

[Hardness of thermally conductive silicone rubber]
Measured based on JIS K 6249.

[Thermal conductivity of thermally conductive silicone rubber]
Measurements were made based on the ASTM E 1530 protective heat flow meter method.

[Tensile shear strength of thermally conductive silicone rubber]
It implemented by the method based on JISK6249.

[Aluminum / aluminum shearing adhesive strength of thermally conductive silicone rubber]
Measured based on JIS K 6249.
That is, as shown in FIG. 1, two aluminum plates are bonded with a cured product of a heat conductive silicone rubber composition so as to have an adhesive area of 2.5 cm ² and an adhesive layer of 2 mm, and an adherend for a shear adhesion test. Was made. The adherend for shear adhesion test was pulled in the tensile direction shown in FIG. 1 at a pulling speed of 50 mm / min, and the shear bond strength of the heat conductive silicone rubber was measured.

注）１：成形加工性が非常に悪い。
注）２：成形加工物が脆い為、測定不可能。

Note) 1: Molding processability is very poor.
Note 2) Measurement is impossible because the molded product is brittle.

It is the schematic which shows the to-be-adhered body for a tensile-shear-adhesion test in the Example of this invention, and a test method.

Explanation of symbols

1 Aluminum plate 2 Adhesive layer (silicone rubber)

Claims (8)

(A) The following formula (ii) having (i) two or more silicon atom-bonded alkenyl groups and (ii) one or more hydrolyzable silyl groups in one molecule

(In the formula, t ′ is an integer of 1 to 20, u ′ is an integer of 5 or more and less than 99, v ′ is an integer of 5 to 400, and the sum of t ′ + u ′ is 6 or more and less than 100.)
An organopolysiloxane having a structure represented by :
(B) a curing agent comprising an organohydrogenpolysiloxane containing an average of two or more silicon-bonded hydrogen atoms in one molecule and a platinum catalyst ,
( C) containing a thermally conductive filler, ( A) component addition amount is 0.1 to 30 parts by mass with respect to 100 parts by mass of (C) component, and (B) component organohydrogenpolysiloxane The amount of silicon-bonded hydrogen atoms is 0.1 to 6.0 moles per mole of total silicon-bonded alkenyl groups in all components, and the platinum-based catalyst content is (A ) Component and (B) the total mass of the organohydrogenpolysiloxane of the component, the platinum-based catalyst is in an amount of 0.01 to 1,000 ppm by mass unit, and the content of (C) component is (C The heat conductive silicone rubber composition is characterized in that the mass of the component occupies 75 to 98 mass% of the total mass of all components . In formula (ii), 'a is 5~94, t' u + u sum 6-9 5 a is claim 1 thermally conductive silicone rubber composition according to '. Furthermore, (D) an organopolysiloxane having a viscosity at 25 ° C. of 50 to 100,000 mPa · s and containing an average of 2 to 20 silicon-bonded alkenyl groups in one molecule, and / or (E) look-containing organopolysiloxane having a structure represented by (IV), the total content of the component (D) and (E) component, 0.1 to 20 parts by weight per 100 parts by weight component (C) The heat conductive silicone rubber composition according to claim 1 or 2 .

(In the formula, B is a methyl group, an alkenyl group or —Z—SiR ² ₃ , R ² is an alkoxy group having 1 to 4 carbon atoms, an alkenyloxy group or an acyloxy group, and Z is an oxygen atom or a carbon atom) ( It is a divalent hydrocarbon group of 2 to 10 and w is an integer of 5 to 300.) The heat conductive silicone rubber composition according to claim 3, wherein the content of the component (E) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (C). (C) a thermally conductive filler component, inorganic powders and / or thermally conductive silicone rubber composition according to any one of claims 1 to 4, characterized in that a metal powder. The inorganic powder is at least one inorganic powder selected from the group consisting of aluminum oxide, zinc oxide, silicon oxide, silicon carbide, silicon nitride, magnesium oxide, aluminum nitride, boron nitride, and graphite, and the metal powder 6. The thermally conductive silicone rubber composition according to claim 5 , wherein is at least one metal powder selected from the group consisting of aluminum, copper, silver, gold, nickel, iron and stainless steel. A molded product obtained by curing the thermally conductive silicone rubber composition according to any one of claims 1 to 6 . The molded article according to claim 7, wherein the thermal conductivity is 1.5 W / mK or more.

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