WO2020031669A1 - Silicone composition and method for manufacturing same - Google Patents

Abstract

Provided is a silicone composition including an inorganic filler that takes the form of particles having a specific shape defined by the specific surface area calculated from the BET specific area and the average particle diameter on the assumption that the particles have a spherical shape. The inclusion of the inorganic filler makes it possible to suppress the deterioration of the performance of the silicone composition, such deterioration caused by cracks and shifts that are generated during a cooling/heating cycle.

Description

Silicone composition and method for producing the same

The present invention relates to a silicone composition and a method for producing the same. Specifically, regarding a silicone composition having thermal conductivity, an inorganic filler having a specific particle shape, which is calculated from the BET specific surface area and the average particle diameter, is defined by the specific surface area assuming a spherical shape, is blended. Accordingly, the present invention relates to a thermally conductive silicone composition and a method for producing the same, which are capable of suppressing performance deterioration due to cracks and deviations during a thermal cycle.

で は In the field of electrical and electronic equipment and transport equipment, more and more electronic elements and components are increasingly mounted in order to precisely control the energy used. For example, focusing only on transport aircraft, changing from gasoline vehicles to hybrid vehicles, plug-in hybrid vehicles, electric vehicles, fuel cell vehicles, etc., motors, inverters, and batteries that were not necessary until now for gasoline vehicles It has become necessary to mount electronic elements and components such as. In the case of body systems such as engine control, power train system, and air conditioner control, the content of the control is becoming more sophisticated, and the number of systems required for the control is increasing. Accordingly, the number of electronic elements mounted therein has been increasing. A thermally conductive silicone composition is now indispensable for efficiently releasing heat from such heat-generating electronic elements and components and transmitting the heat to a cooler.

More recently, many electronic elements and components have to be mounted in a limited space, and the mounting environment (temperature, angle, etc.) has also become diverse. For example, electronic elements / parts that generate heat and the cooling plate are no longer placed horizontally, and a heat conductive material connecting them is often mounted with a certain inclination. In such a use environment, an additional one-pack type thermally conductive silicone composition may be used to prevent the thermally conductive material from slipping out of the space between the heating element and the cooling element (Japanese Patent No. 3580366). : Patent Document 1). That is, the heat curing hardens the heat conductive composition from the gap between the heating element and the cooling body, and as a result, the heat radiation property is maintained for a long time. However, this one-part type thermally conductive silicone composition also had some problems. For example, refrigeration or freezing is required for storage, and thawing is required before use. In addition, since heating and cooling are required when assembling the additional one-component thermally conductive silicone composition, it is necessary to introduce a heating furnace / cooling furnace into a production facility using the material, or to perform heating for a long time. There was a problem that the production efficiency was reduced due to the necessity of a cooling step. Further, even from the viewpoint of energy efficiency, such a heating step must be heated not only for the thermally conductive material but also for each part, and thus cannot be said to be an efficient step.

Further, if metal cutting oil containing an amine compound or the like which is a curing inhibitor remains on the coated surface, there is a problem that poor curing occurs. Furthermore, there has been a problem that the excess addition reaction proceeds due to the exhaust heat from the heating element, so that the hardness of the heat conductive material increases with time, and stresses the mounted elements and the like.

Therefore, when the additional one-pack type thermally conductive silicone composition is used, the time required for such storage / thaw management and heating / cooling steps is omitted, and heating is performed in advance during material production so as not to worry about curing inhibition. A thermally conductive material subjected to a cross-linking reaction has been found (Japanese Patent No. 4130091: Patent Document 2). This is a thermally conductive silicone composition that overcomes the above-mentioned disadvantages, but as a trade-off, it is difficult to apply because the viscosity is high and the thermal conductive filler is difficult to highly fill due to the high viscosity of the base polymer. A new challenge has arisen. In addition, it is impossible to take a dense three-dimensional cross-link due to the heat cross-linking reaction at the time of material production.Because it is a loose gel cross-linked product, it is necessary to completely suppress the deviation between the heating element and the cooling element. Was difficult.

On the other hand, although the viscosity is low in the initial stage, after application, it is hardened or thickened by using the moisture in the air in the room temperature environment, making it difficult to slip out of the gap between the heating element and the cooling element, and it can also be stored at room temperature Various condensation-curable heat conductive silicone compositions have been proposed (Japanese Patent Application Laid-Open No. 2004-352947, Japanese Patent No. 4787128, Japanese Patent No. 57333087: Patent Documents 3 to 5). This is a material that is useful in that it does not require refrigeration or freezing for storage, does not require a heating / cooling process when mounted, and has high production efficiency, but is cured by utilizing moisture in the air. As a result, they commonly have a disadvantage that they are inferior in deep curing properties. As a result, when a thermal load such as heat resistance or a cooling / heating cycle is applied, there is a problem that a cured product of the composition is deteriorated such as cracks or deviations, and heat radiation characteristics are reduced.

Japanese Patent No. 3580366 Japanese Patent No. 4130091 JP 2004-352947 A Japanese Patent No. 4787128 Japanese Patent No. 5733087

The present invention has been made in view of the above circumstances, and does not require refrigeration or freezing storage, and further does not require a heating / cooling step at the time of mounting, so that production efficiency is high, and cracks and deviations during a cooling / heating cycle are eliminated. An object of the present invention is to provide a thermally conductive silicone composition and a method for producing the same, which are capable of suppressing performance degradation caused by the composition.

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, calculated from the BET specific surface area and the average particle diameter, defined by the specific surface area assuming a spherical shape, the inorganic filler having a specific particle shape It has been found that by adding an agent, it is possible to obtain a silicone composition capable of suppressing performance deterioration due to cracks and misalignments during a cooling / heating cycle, and has accomplished the present invention.

Accordingly, the present invention provides the following silicone composition and a method for producing the same.
[1].
(A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass;
(B) Organohydrogenpolysiloxane having two or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule: SiH based on the total number of aliphatic unsaturated hydrocarbon groups in component (A) An amount such that the number of groups is 0.5 to 5,
(C) a platinum group metal catalyst: an effective amount,
(E) at least one inorganic filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides and allotropes of carbon: 100 per 100 parts by mass of component (A) A silicone composition containing up to 5,000 parts by mass as an essential component, and the component (E) satisfies the following formula:

However,
i, n: natural numbers, i = 1 to n, where n is the number of types of the inorganic filler contained in the component (E) e: the total of the blending amounts of the component (E) e _i : (Ei) In the compounding amount of the component, the component (Ei) is one kind of the inorganic filler P _{i in} the component (E): a value P _i defined by the following formula: (BET specific surface area of the component (Ei)) ÷ (Specific surface area assuming spherical shape, calculated from the average particle size of (Ei) component)
It is.
[2].
The silicone composition according to [1], further comprising (D) a reaction control agent in an amount of 0.04 to 5 parts by mass based on 100 parts by mass of the component (A).
[3].
The silicone according to [1] or [2], further comprising (F) 1 to 200 parts by mass of a hydrolyzable organopolysiloxane compound represented by the following general formula (1) based on 100 parts by mass of component (A). Composition.

(In the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and each R ¹ may be the same or different. It represents an integer of 5 to 100.)
[4].
The silicone composition according to any one of [1] to [3], wherein the component (E) has an average particle size of 0.01 to 1,000 μm.
[5].
The silicone composition according to any one of [1] to [4], comprising a heat crosslinked product containing the components (A) to (C) and (E).
[6].
A method for producing a silicone composition, wherein the following components (A) to (C) and (E) are cross-linked while being heated and mixed.
(A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass;
(B) Organohydrogenpolysiloxane having two or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule: SiH based on the total number of aliphatic unsaturated hydrocarbon groups in component (A) An amount such that the number of groups is 0.5 to 5,
(C) a platinum group metal catalyst: an effective amount,
(E) at least one inorganic filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides and allotropes of carbon: 100 per 100 parts by mass of component (A) 5,000 parts by mass provided that the component (E) satisfies the following expression.

However,
i, n: natural numbers, i = 1 to n, where n is the number of types of the inorganic filler contained in the component (E) e: the total of the blending amounts of the component (E) e _i : (Ei) In the compounding amount of the component, the component (Ei) is one kind of inorganic filler P _{i in} the component (E): a value P _i defined by the following formula: = (BET specific surface area of the component (Ei)) ÷ (Specific surface area assuming spherical shape, calculated from the average particle size of (Ei) component)
[7].
(6) The cross-linking is carried out while heating and mixing 0.04 to 5 parts by mass of the reaction control agent (D) with 100 parts by mass of the component (A) together with the components (A) to (C) and (E). A method for producing a silicone composition.

The silicone composition of the present invention suppresses performance deterioration caused by cracks and misalignments at the time of cooling, which does not require refrigeration or freezing storage, does not require a heating / cooling step at the time of mounting, and which are difficult with conventional techniques. And can be used in a wide range of fields requiring heat radiation and cooling / heat resistance, such as electric and electronic fields and transport equipment fields.

Hereinafter, the present invention will be described in detail.

Component (A) The component (A) has at least one, preferably 1 to 2 aliphatic unsaturated hydrocarbon groups in one molecule, and has a kinematic viscosity at 25 ° C of 60 to 100,000 mm ² /. s is an organopolysiloxane.

The aliphatic unsaturated hydrocarbon group is preferably a monovalent hydrocarbon group having an aliphatic unsaturated bond and having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and more preferably an alkenyl group. . Examples include alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and octenyl. Particularly preferred is a vinyl group. The aliphatic unsaturated hydrocarbon group may be bonded to any of a silicon atom at the terminal of the molecular chain and a silicon atom in the middle of the molecular chain, or may be bonded to both.

Examples of the organic group other than the aliphatic unsaturated hydrocarbon group bonded to the silicon atom of the organopolysiloxane include C 1 to C 18, preferably C 1 to C 10, more preferably C 1 to C 8, It is a substituted or substituted monovalent hydrocarbon group. For example, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, and decyl group; Aryl groups such as phenyl group, tolyl group, xylyl group, and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, or a part or all of the hydrogen atoms of these groups are fluorine, bromine, chlorine, etc. Substituted with a halogen atom, a cyano group, and the like, for example, a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, and a cyanoethyl group. Among these, a methyl group and a phenyl group are preferable, and a methyl group is particularly preferable.

The organopolysiloxane has a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s, preferably 100 to 30,000 mm ² / s. When the kinematic viscosity is less than 60 mm ² / s, the physical properties of the silicone composition deteriorate, and when it exceeds 100,000 mm ² / s, the extensibility of the silicone composition becomes poor.
In the present invention, the kinematic viscosity is a value at 25 ° C. measured by an Ubbelohde Ostwald viscometer (the same applies hereinafter).

The molecular structure of the organopolysiloxane is not particularly limited as long as it has the above properties, and examples thereof include a linear structure, a branched structure, a partially branched structure, or a linear structure having a cyclic structure. . In particular, those having a linear structure in which the main chain is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with a triorganosiloxy group are preferred. The organopolysiloxane having a linear structure may have a partially branched structure or a cyclic structure.
These organopolysiloxanes can be used alone or in combination of two or more.

Component (B) The component (B) is composed of two or more, preferably three or more, particularly preferably 3 to 100, and more preferably 3 to 20 hydrogen atoms (SiH groups) bonded to a silicon atom in one molecule. And organohydrogenpolysiloxanes. The organohydrogenpolysiloxane is capable of forming a crosslinked structure by the addition reaction of the SiH group in the molecule with the aliphatic unsaturated hydrocarbon group of the component (A) in the presence of a platinum group metal catalyst. I just need. In addition, the SiH group may be bonded to any of a silicon atom at the terminal of the molecular chain and a silicon atom in the middle of the molecular chain, or may be bonded to both.

The molecular structure of the organohydrogenpolysiloxane is not particularly limited as long as it has the above properties, and is a linear structure having a linear structure, a branched structure, a cyclic structure, a partially branched structure or a cyclic structure. And the like. Preferred are a linear structure and a cyclic structure.

The organohydrogenpolysiloxane has a kinematic viscosity at 25 ° C. of preferably 1 to 1,000 mm ² / s, more preferably 10 to 100 mm ² / s. When the kinematic viscosity is 1 mm ² / s or more, there is no possibility that the physical properties of the silicone composition are reduced. When the kinematic viscosity is 1,000 mm ² / s or less, the extensibility of the silicone composition may be poor. There is no. The organohydrogenpolysiloxane preferably has 2 to 100, more preferably 5 to 50, silicon atoms in one molecule.

Examples of the organic group bonded to the silicon atom of the organohydrogenpolysiloxane include a monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon group. Particularly, it is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12, preferably 1 to 10 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, aryl groups such as phenyl group, aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group, hydrogen of these Those in which some or all of the atoms have been substituted with halogen atoms such as fluorine, bromine, chlorine, etc., cyano groups, epoxy ring-containing organic groups (glycidyl groups or glycidyloxy group-substituted alkyl groups), for example, chloromethyl group, chloropropyl Groups, bromoethyl group, trifluoropropyl group, cyanoethyl group, 2-glycidoxyethyl group, 3-glycidoxypropyl group, 4-glycidoxybutyl group and the like. Among these, a methyl group is preferred.
The organohydrogenpolysiloxane may be used alone or in combination of two or more.

The amount of the organohydrogenpolysiloxane of the component (B) is such that the number of SiH groups in the component (B) is 0.5 to 5 relative to the total number of aliphatic unsaturated hydrocarbon groups in the component (A). Amount, preferably an amount of 0.6 to 2, more preferably an amount of 0.7 to 1.5. When the amount of the component (B) is less than the above lower limit, the addition reaction does not proceed sufficiently and the crosslinking becomes insufficient. If the content exceeds the upper limit, the crosslinked structure becomes non-uniform, and the storage stability of the composition is significantly deteriorated.

Component (C) The platinum group metal catalyst of the component (C) is a hydrosilylation catalyst and functions to promote the above-mentioned addition reaction. As the platinum group metal catalyst, a conventionally known catalyst used for an addition reaction can be used. For example, platinum-based, palladium-based, and rhodium-based catalysts can be mentioned, and among them, platinum or a platinum compound which is relatively easily available is preferable. For example, a simple substance of platinum, platinum black, chloroplatinic acid, a platinum-olefin complex, a platinum-alcohol complex, a platinum coordination compound and the like can be mentioned. The platinum group metal catalyst may be used alone or in combination of two or more.

The compounding amount of the component (C) may be an effective amount as a catalyst, that is, an effective amount necessary to promote the addition reaction and cure the composition of the present invention. In particular, the amount is 0.1 to 500 ppm, more preferably 1 to 200 ppm, based on the mass of the platinum group metal atom, based on the component (A). If the amount of the catalyst is less than the above lower limit, the effect as a catalyst may not be obtained. Further, exceeding the above upper limit is not preferable because the catalytic effect does not increase and is uneconomical.
The platinum group metal catalyst may be used after being diluted with an organic solvent such as toluene or a polyorganosiloxane in order to improve the dispersibility in the silicone composition.

(D) Component The silicone composition of the present invention may further contain (D) a reaction control agent. The reaction control agent of the component (D) functions to suppress the progress of the hydrosilylation reaction at room temperature and to extend shelf life and pot life.
As the reaction control agent, a conventionally known control agent used for an addition-curable silicone composition can be used. For example, acetylene compounds such as acetylene alcohols (eg, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), and various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole And organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

When the component (D) is compounded, the amount is preferably 0.04 to 5 parts by mass, more preferably 0.04 to 2 parts by mass, per 100 parts by mass of the component (A). If the amount of the reaction control agent is less than the lower limit, the desired sufficient shelf life and pot life may not be obtained, and if the amount exceeds the upper limit, the curability of the silicone composition may decrease.
The reaction control agent may be used after being diluted with toluene or the like in order to improve the dispersibility in the silicone composition.

Component (E) The component (E) is at least one member selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon, preferably one to three, and furthermore, Preferred are one or two inorganic fillers. For example, aluminum, silver, copper, metallic silicon, alumina, zinc oxide, magnesium oxide, aluminum oxide, silica (silicon dioxide), cerium oxide, iron oxide, aluminum hydroxide, cerium hydroxide, aluminum nitride, boron nitride, silicon carbide , Diamond, graphite, carbon nanotube, graphene and the like. The component (E) is preferably a metal oxide, more preferably silica, aluminum oxide, or zinc oxide.
These can be used alone or in combination of two or more.

When the average particle diameter of the component (E) is less than 0.01 μm, the viscosity of the obtained composition may be too high, and the extensibility may be poor. Because of the possibility of uniformity, the thickness is desirably in the range of 0.01 to 1,000 μm, preferably in the range of 0.05 to 500 μm, and more preferably in the range of 0.1 to 100 μm. The average particle diameter can be determined, for example, as a mass average value (or median diameter) in a particle size distribution measurement by a laser light diffraction method.

Further, the component (E) satisfies the following expression.

However,
i, n: natural numbers, i = 1 to n, where n is the number of types of the inorganic filler contained in the component (E) e: the total of the blending amounts of the component (E) e _i : (Ei) In the compounding amount of the component, the component (Ei) is one kind of inorganic filler P _{i in} the component (E): a value P _i defined by the following formula: = (BET specific surface area of the component (Ei)) ÷ (Specific surface area assuming spherical shape, calculated from the average particle size of (Ei) component)

That is, the above equation is represented by the following equation.

Here, i is 1 to n, and n is the number of types of the inorganic filler contained in the component (E). For example, even if the silica is the same, the average particle diameter, the shape, and the like are the same. Different ones are of different types.
e is the total amount of the component (E) and is represented by the following formula.

The component (Ei) is one kind of inorganic filler in the component (E). For example, when three kinds of inorganic fillers are used as the component (E) (i = 1 to 3, n = 3), where (E-1), (E-2) and (E-3) are the components, respectively, where e _i is e ₁ and P _i is P ₁ , e _i in the (E-2) component is e ₂ , P _i is P ₂ , and e _i in the (E-3) component is e ₃ , and P _i is P ₃ .

In the above equation, when a certain component (Ei) is viewed alone, the closer to a true sphere, the closer to 1. Conversely, the value increases as the distance from the sphere increases. That is, the meaning of the above formula can be rephrased as a case where the proportion of the non-spherical component is large when the component (E) is viewed as a whole, or a component having a shape far from a true sphere exists, or both.

The shape of each component (E), which is an inorganic filler, is not particularly limited as long as the above formula is satisfied. Examples of the shape include spherical, round, polyhedral, irregular, needle-like, flat, and crushed shapes. Things.

The amount of component (E) is 100 to 5,000 parts by mass, preferably 200 to 4,000 parts by mass, per 100 parts by mass of component (A). With this amount, the silicone composition of the present invention can ensure sufficient thermal conductivity and extensibility.

(F) Component The silicone composition of the present invention may further contain a hydrolyzable organopolysiloxane compound (F) represented by the following general formula (1). The hydrolyzable organopolysiloxane compound of the component (F) is used for treating the surface of the inorganic filler, and plays a role in assisting the filling of the filler to a high degree.

(In the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and each R ¹ may be the same or different. It represents an integer of 5 to 100.)

R ¹ in the above formula (1) is a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and is preferably a monovalent saturated aliphatic group which may have a substituent. A hydrocarbon group, a monovalent unsaturated aliphatic hydrocarbon group which may have a substituent, and a monovalent aromatic hydrocarbon group (including an aromatic heterocycle) which may have a substituent, and more preferably Is a monovalent saturated aliphatic hydrocarbon group which may have a substituent, a monovalent aromatic hydrocarbon group which may have a substituent (including an aromatic heterocycle), and particularly preferably It is a monovalent saturated aliphatic hydrocarbon group which may have a group.

Specific examples of the monovalent saturated aliphatic hydrocarbon group which may have a substituent include a linear group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Branched alkyl groups such as alkyl group, isopropyl group, isobutyl group, tert-butyl group, isopentyl group, neopentyl group and ethylhexyl group; cycloalkyl group such as cyclopentyl group, cyclohexyl group and cycloheptyl group; chloromethyl group; C1-C20, preferably C1-C14, more preferably C1-C12, such as halogen-substituted alkyl groups such as chloropropyl group, 3,3,3-trifluoropropyl group and bromopropyl group. Things.

Specific examples of the monovalent unsaturated aliphatic hydrocarbon group which may have a substituent include an alkenyl group such as an ethenyl group, a 1-methylethenyl group and a 2-propenyl group, an ethynyl group, and a 2-propynyl group. It has 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 2 to 6 carbon atoms, such as an alkynyl group.

Specific examples of the optionally substituted monovalent aromatic hydrocarbon group (including an aromatic hetero ring) include an aryl group such as a phenyl group, a tolyl group and a naphthyl group, a benzyl group, and 2-phenylethyl. A aralkyl group such as a group, a halogen-substituted aryl group such as an α, α, α-trifluorotolyl group, a chlorobenzyl group, an aromatic hetero ring such as a furyl group, a thienyl group, etc., having 4 to 20 carbon atoms, preferably 4 to 12.

Among them, R ¹ is preferably a methyl group, an ethyl group, a 3,3,3-trifluoropropyl group or a phenyl group, more preferably a methyl group, an ethyl group or a phenyl group, and particularly preferably a methyl group. It is.

Δm is an integer of 5 to 100, preferably an integer of 10 to 70.

(F) kinematic viscosity at 25 ° C. of the component, usually preferably 5 ~ 100,000mm ² / s, more preferably 10 ~ 50,000mm ² / s. If the kinematic viscosity is lower than 5 mm ² / s, oil bleed is likely to be generated from the cured composition, and the composition may be easily dripped. If the kinematic viscosity is higher than 100,000 mm ² / s, the fluidity of the obtained composition will be poor, and the coating workability may be deteriorated.

When the component (F) is compounded, the amount is 1 to 200 parts by mass, preferably 10 to 150 parts by mass, per 100 parts by mass of the component (A). If the amount is too small, the inorganic filler as the component (E) may be difficult to fill. On the other hand, if the amount is too large, oil bleed may easily occur from the composition after curing, and the curing reaction becomes insufficient.

Other Ingredients The silicone composition of the present invention may contain a non-reactive organo (poly) siloxane such as methylpolysiloxane to adjust the viscosity of the composition. Further, in order to prevent deterioration of the silicone composition, a conventionally known antioxidant such as 2,6-di-tert-butyl-4-methylphenol may be contained as necessary. Further, an adhesion aid, a release agent, a dye, a pigment, a flame retardant, an anti-settling agent, a thixotropy improver, and the like can be added as necessary.

The method for producing the silicone composition in the present invention is not particularly limited, but the components (A) to (C) and (E) described above, and if necessary, the components (D) and (F) and other components may be used. For example, Trimix, Twin Mix, Planetary Mixer (all are registered trademarks of a mixer manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (registered trademark of a mixer manufactured by Mizuho Industry Co., Ltd.), Hibis Dispermix (special machine) A method of mixing using a mixer such as a chemical compounder (registered trademark of Chemical Industry Co., Ltd.) is used. When the component (F) is added, it may be added in the step of mixing the components (A) and (E).

The silicone composition of the present invention may be mixed while heating, or may be crosslinked while heating. The heating conditions are not particularly limited, but the temperature is usually 25 to 200 ° C, preferably 60 to 180 ° C, particularly preferably 80 to 170 ° C, and the time is usually 3 minutes to 24 hours, preferably 5 minutes to It is 12 hours, particularly preferably 10 minutes to 6 hours.

シ リ コ ー ン The silicone composition of the present invention has a viscosity measured at 25 ° C of preferably 1 to 1,000 Pa · s, more preferably 10 to 700 Pa · s, and still more preferably 50 to 600 Pa · s. When the viscosity is less than 1 Pa · s, workability may be deteriorated, such as difficulty in maintaining the shape. In addition, when the viscosity exceeds 1,000 Pa · s, there is a possibility that workability may be deteriorated, such as difficulty in ejection and application. The viscosity can be obtained by adjusting the amount of each component described above.

シ リ コ ー ン The silicone composition of the present invention is thermally conductive and usually has a thermal conductivity of 0.5 to 10 W / m · K. The thermal conductivity can be measured using TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd.

Since the silicone composition of the present invention does not require refrigeration or freezing storage, and further does not require a heating / cooling step at the time of mounting, it has high production efficiency and further suppresses performance deterioration due to cracks and deviations during a cooling / heating cycle. It is possible to do. Because of these characteristics, it can be used in a wide range of fields where heat radiation and heat resistance are required, such as in the field of electric and electronic equipment and transport equipment.

Hereinafter, 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. The kinematic viscosity indicates a value at 25 ° C. measured by an Ubbelohde Ostwald viscometer. The value of the average particle size is the median diameter D ₅₀ was measured with a laser diffraction / scattering type particle size measuring apparatus (LA-750 :( Ltd.) Horiba). Further, the value of the BET specific surface area was measured with an Automatic Surface Area Analyzer (Macsorb HM-model 1201: manufactured by MOUNTEC).

First, the following components for preparing the silicone composition of the present invention were prepared.

(A) Component A-1:
Diphenyl dimethylpolysiloxane having a kinematic viscosity at 25 ° C of 700 mm ² / s at 25 ° C, wherein both terminals represented by the following formula (2) are blocked with a dimethylvinylsilyl group and a trimethylsilyl group.

(However, a / (a + b) = 0.05, and Ph represents a phenyl group.)

A-2:
Dimethylpolysiloxane having a kinematic viscosity at 25 ° C. of 800 mm ² / s, wherein both terminals represented by the following formula (3) are blocked with dimethylvinylsilyl and trimethylsilyl groups.

(However, c is a number that becomes the above kinematic viscosity.)

(B) Component B-1:
Methyl hydrogen dimethylpolysiloxane having a kinematic viscosity at 25 ° C. of 28 mm ² / s, wherein both terminals represented by the following formula (4) are blocked with a trimethylsilyl group:

B-2:
Methyl hydrogen dimethylpolysiloxane having a kinematic viscosity at 25 ° C. of 100 mm ² / s, wherein both terminals represented by the following formula (5) are blocked with a trimethylsilyl group:

(C) Component C-1:
A solution obtained by dissolving a platinum-divinyltetramethyldisiloxane complex in dimethylpolysiloxane having a kinematic viscosity of 600 mm ² / s at 25 ° C., both ends of which are blocked with a dimethylvinylsilyl group (platinum atom content: 1 as platinum atom) mass%)

(D) Component D-1:
50% by mass toluene solution of 1-ethynylcyclohexanol represented by the following formula (6)

(E) Component E-1: crystalline silica powder E-2 having an average particle size of 1.2 μm E-2: crystalline silica powder E-3 having an average particle size of 0.7 μm: crystalline silica powder E having an average particle size of 3.0 μm -4: aluminum oxide powder E-5 having an average particle diameter of 1.5 μm: zinc oxide powder E-6 having an average particle diameter of 0.4 μm: aluminum oxide powder E-7 having an average particle diameter of 0.2 μm: average particle diameter of 4. 0μm spherical silica powder

Table 1 below summarizes various physical properties of the prepared E-1 to E-7 components.

P _i = (BET specific surface area of component (Ei)) ÷ (specific surface area assuming spherical shape, calculated from average particle diameter of component (Ei))

(F) Component F-1:
A dimethylpolysiloxane having a kinematic viscosity at 25 ° C. of 30 mm ² / s in which one end represented by the following formula (7) is blocked with a trimethylsilyl group and the other end is blocked with a trimethoxysilyl group.

[Examples 1 to 10, Comparative Examples 1 to 8]
Preparation of Silicone Composition The components (A) to (F) were blended according to the methods shown below in accordance with the amounts shown in Tables 2 to 5 below to prepare a silicone composition. Note that SiH / SiVi (number ratio) is a ratio of the total number of SiH groups in the component (B) to the total number of aliphatic unsaturated hydrocarbon groups in the component (A).
The components (A), (E) and (F) were added to a 5 liter planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) and mixed at 170 ° C. for 1 hour. Cool to 40 ° C. or lower, then add components (B) and (D) and mix until uniform, then add component (C) and mix at 150 ° C. for 1.5 hours, A composition was prepared.
With respect to each composition obtained by the above method, the viscosity and the thermal conductivity were measured according to the following methods, and further, the displacement and cracking during a cooling / heating cycle were evaluated. The results are shown in Tables 2 to 5.

[viscosity]
The absolute viscosity of each composition was measured at 25 ° C. using a Malcolm viscometer (type PC-1T) (rotor A: 10 rpm, shear rate: 6 [1 / s]).

[Thermal conductivity]
Each composition was wrapped in kitchen wrap, and the thermal conductivity was measured with TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd.

[Displacement and cracking during cooling / heating cycle]
0.1 ml of each composition was sandwiched between glass plates and compressed for 15 minutes using two 1.8 kgf clips. The area of the composition at this point is defined as α. This was placed vertically in a thermal shock tester at −65 ° C./30 minutes⇔150 ° C./30 minutes, and was taken out after 500 cycles. The area at this point was defined as β, and the deviation was quantified by the equation β ÷ α. Further, of the area β, the area (= γ) of the region where the composition was not present was quantified by image processing, and the crackability was quantified by the equation γ ÷ β.
That is, it is evaluated that the smaller the value of β ÷ α, the better the displacement resistance, and the smaller the value of γ ÷ β, the more excellent the crack resistance.

From the results in Tables 2 to 5, in the silicone compositions of Examples 1 to 10 satisfying the requirements of the present invention, the values of the slippage property (β ÷ α) and the cracking property (γ ÷ β) are small. That is, it can be determined that the resistance to displacement and the resistance to cracking are excellent. On the other hand, the silicone compositions of Comparative Examples 1 to 8 have large values of the slippage property (β ÷ α) and the cracking property (γ ÷ β). That is, it is determined that the resistance to displacement and the resistance to cracking are poor.
Therefore, it was confirmed that the silicone composition of the present invention was able to suppress performance deterioration due to cracks and deviations during a cooling / heating cycle. Due to these properties, the silicone composition of the present invention can be used in a wide range of fields where heat radiation and cooling / heat resistance are required, such as in the field of electrical and electronic equipment and transport equipment.

Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of

Claims (7)

1. (A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass;
   (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule: SiH based on the total number of aliphatic unsaturated hydrocarbon groups in component (A) An amount such that the number of groups is 0.5 to 5,
   (C) a platinum group metal catalyst: an effective amount,
   (E) at least one inorganic filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon: 100 per 100 parts by mass of component (A) A silicone composition containing up to 5,000 parts by mass as an essential component, and the component (E) satisfies the following formula:
   

   

   However,
   i, n: natural numbers, i = 1 to n, where n is the number of types of the inorganic filler contained in the component (E) e: the total of the blending amounts of the component (E) e _i : (Ei) In the compounding amount of the component, the component (Ei) is one kind of inorganic filler P _{i in} the component (E): a value P _i defined by the following formula: = (BET specific surface area of the component (Ei)) ÷ (Specific surface area assuming spherical shape, calculated from the average particle size of (Ei) component)
   It is.
2. シ リ コ ー ン The silicone composition according to claim 1, further comprising 0.04 to 5 parts by mass of (D) a reaction control agent based on 100 parts by mass of component (A).
3. The silicone composition according to claim 1, further comprising (F) 1 to 200 parts by mass of a hydrolyzable organopolysiloxane compound represented by the following general formula (1) based on 100 parts by mass of component (A). .
   

   

   (In the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and each R ¹ may be the same or different. It represents an integer of 5 to 100.)
4. (4) The silicone composition according to any one of (1) to (3), wherein the component (E) has an average particle size of 0.01 to 1,000 μm.
5. The silicone composition according to any one of claims 1 to 4, comprising a heat crosslinked product containing the components (A) to (C) and (E).
6. A method for producing a silicone composition, in which the following components (A) to (C) and (E) are cross-linked while being heated and mixed.
   (A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass;
   (B) Organohydrogenpolysiloxane having two or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule: SiH based on the total number of aliphatic unsaturated hydrocarbon groups in component (A) An amount such that the number of groups is 0.5 to 5,
   (C) a platinum group metal catalyst: an effective amount,
   (E) at least one inorganic filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon: 100 per 100 parts by mass of component (A) 5,000 parts by mass provided that the component (E) satisfies the following expression.
   

   

   However,
   i, n: natural numbers, i = 1 to n, where n is the number of types of the inorganic filler contained in the component (E) e: the total of the blending amounts of the component (E) e _i : (Ei) In the compounding amount of the component, the component (Ei) is one kind of inorganic filler P _{i in} the component (E): a value P _i defined by the following formula: = (BET specific surface area of the component (Ei)) ÷ (Specific surface area assuming spherical shape, calculated from the average particle size of (Ei) component)
7. The cross-linking is carried out while heating and mixing 0.04 to 5 parts by mass of the reaction control agent (D) with 100 parts by mass of the component (A) together with the components (A) to (C) and (E). A method for producing a silicone composition.