JP3232009B2 - Organopolysiloxane composition for electrical insulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an essentially non-foamable organopolysiloxane composition for electrical insulation, which is excellent in redispersibility of an inorganic filler.

[0002]

2. Description of the Related Art A low-viscosity addition reaction-curable liquid organopolysiloxane composition containing alkenyl group-containing organopolysiloxane, organohydrogenpolysiloxane and platinum-based catalyst as basic components has been known.
The cured product of this composition has electrical insulation, moisture resistance, water resistance,
Excellent vibration absorption, thermal shock resistance, self-extinguishing properties, etc.
The casting and curing operations of the composition are also relatively simple.
Therefore, this composition has been conventionally used in large quantities as a casting material for electric and electronic components such as high-voltage flyback transformer coils for televisions, high-voltage rectifier circuits, motor coils, transformer circuits, and the like. By the way, these casting materials are generally required to have good fluidity and good impregnation at the application site. Therefore, these casting materials are blended with a low-viscosity base oil (base polymer in the composition) and an inorganic filler such as silica or alumina having a relatively large particle size. However, since this inorganic filler has a higher specific gravity than the base oil, it has a drawback that it sediments and accumulates on the bottom of the container during storage. Also, since the inorganic filler itself has a high hardness, the sediment that has settled forms a hard cake.
And there is also a problem that the cake becomes harder to be mechanically crushed if stored for a long period of time.

[0003] Therefore, in order to easily and easily redisperse the inorganic filler deposited on the bottom of the container during storage, fine powder silica such as fumed silica is used as the inorganic filler. Is known. However, compositions containing finely divided silica have increased viscosity,
In addition, since the thixotropic property becomes strong, there is a disadvantage that the fluidity is significantly reduced.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inorganic filler which has good fluidity and can easily and easily redisperse an inorganic filler deposited on the bottom of a container during storage.
An essentially non-foaming organopolysiloxane composition for electrical insulation, which can provide a cured product excellent in heat dissipation, low thermal expansion, flame retardancy, and the like, and can reduce the cost of the composition. The object is to provide an organopolysiloxane composition for electrical insulation that can achieve the following.

[0005]

According to the present invention, there is provided (A) a general composition formula (1): R ¹ _a R ² _b SiO _{(4-ab) / 2} (1) wherein R ¹ is independently a fat An unsubstituted or substituted monovalent hydrocarbon group containing no group unsaturated bond, R ² is an alkenyl group, a is 1.5 to 2.0, b is 0.003 to 0.5, and a + b = 2.00 to 2.07 Is a number that satisfies
An organopolysiloxane having an average of 30 to 600 silicon atoms in one molecule and containing at least two alkenyl groups bonded to the silicon atoms,

(B) General composition formula (2): R ³ _{c Hd} SiO _{(4-cd) / 2} (2) (wherein R ³ is independently unsubstituted or substituted without an aliphatic unsaturated bond. Wherein c is 1.0 to 2.0, d is 0.04 to 1.0, and c + d = 1.1 to 2.5
Which satisfies
An organohydrogenpolysiloxane having from to 120 silicon atoms and containing at least two hydrogen atoms bonded to silicon atoms; one alkenyl group in component (A) and silicon in component (B) The amount of 0.5 to 5 hydrogen atoms bonded to the atom,

(C) General composition formula (3) R ⁴ _e (OH) _f SiO _{(4-ef) / 2} (3) wherein R ⁴ is independently a hydrogen atom or unsubstituted or substituted monovalent carbon A hydrogen atom, e is 1.0 to 2.5, and f is a positive number of 1 or less), and has an average of 2 to 300 silicon atoms in one molecule, and is bonded to the silicon atom. An organopolysiloxane containing at least one hydroxyl group; 0.01 to 0.5 parts by weight based on 100 parts by weight of the total of the components (A) and (B);

(D) an inorganic filler having an average particle diameter of 1 to 50 μm ( provided that the spherical or non-spherical filler has an average particle diameter of less than 10 μm)
Alumina fine powder 5-95% by weight and average particle size 10-50μ
95 to 5% by weight of spherical or non-spherical alumina fine powder
Excluding Ranaru fine alumina powder); (A), (B ),
An essentially non-foamable organopolysiloxane composition for electric insulation, comprising 30 to 350 parts by weight and (E) a catalytic amount of platinum or a platinum compound based on 100 parts by weight of the total of component (C).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (A) Organopolysiloxane Containing Alkenyl Group The alkenyl group-containing organopolysiloxane of the component (A) used in the composition of the present invention is the base component of the composition, and the presence of the catalyst of the component (E) The composition is cured by a hydrosilylation reaction (addition reaction) with the organohydrogenpolysiloxane of component (B) below. The component (A) used in the present invention is represented by the above formula (1) and contains at least two alkenyl groups bonded to a silicon atom in one molecule. The molecular structure may be linear, branched or cyclic, but is preferably linear or branched,
From the viewpoint of easy synthesis, the most preferred is a linear diorganopolysiloxane in which the main chain portion is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy units. The viscosity is 25 ° C.
50 to 10,000 cSt is preferred, and more preferably 100 to 5,000 cSt.
It is about 0 cSt.

In the formula (1), examples of the unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond represented by R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, Butyl group, isobutyl group, tert-butyl group,
Alkyl groups such as hexyl group, octyl group, decyl group and dodecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group; aryl groups such as phenyl group, tolyl group and xylyl group; benzyl group and phenylethyl group And aralkyl groups such as phenylpropyl groups; substituted hydrocarbon groups in which part or all of the hydrogen atoms of these hydrocarbon groups have been replaced by halogen atoms such as fluorine, chlorine and bromine atoms or nitrile groups; Usually, those having about 1 to 12 carbon atoms, particularly about 1 to 8 carbon atoms, such as a fluoropropyl group, a chloromethyl group, a bromoethyl group, and a cyanoethyl group are exemplified. In consideration of the chemical stability and ease of synthesis of the resulting organopolysiloxane, all of R ¹ may be a methyl group, a combination of a methyl group and a phenyl group, or a combination of a methyl group and a trifluoropropyl group. It is preferred to select a combination of groups.

In the formula (1), examples of the alkenyl group represented by R ² include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group,
Examples thereof include those having about 2 to 6 carbon atoms such as pentenyl groups. Particularly typical are a vinyl group and an allyl group, and a vinyl group is preferable in consideration of the chemical stability and ease of synthesis, and the alkenyl group is a silicon atom at the terminal of a molecular chain or a silicon atom in the middle of a molecular chain. May be bonded to either or both of them, but from the viewpoint of physical properties such as the curing speed or the mechanical strength of the cured product, it is preferable that the alkenyl group has at least the alkenyl group bonded to the molecular chain terminal. .

In the formula (1), a is from 1.5 to 2.0, preferably
1.7 to 2.0, and b is 0.003 to 0.5, preferably 0.004
And a + b is a number that satisfies 2.00 to 2.07, preferably 2.00 to 2.03. The organopolysiloxane of the component (A) has an average of 30 to 60 per molecule.
It has 0, preferably about 60 to 300 silicon atoms (or the degree of polymerization). If the number of silicon atoms in this molecule is too small, the mechanical strength of the cured product of the composition becomes poor, On the other hand, if the content is too large, the viscosity of the composition becomes high and the fluidity becomes poor. These organopolysiloxanes may be used alone or in combination of two or more. Specific examples of the organopolysiloxane of the component (A) include, for example, those represented by the following formula.

[0013]

Embedded image (Where p is an integer satisfying p + 2 = 30 to 600),

[0014]

Embedded image (Where q and r are each an integer of 1 or more and q + r + 2 = an integer satisfying 30 to 600),

[0015]

Embedded image (Where s is an integer of 1 or more; t is an integer of 2 or more;
And s + t + 2 = integer satisfying 30 to 600)
etc.

(B) Organohydrogen polysiloxane
Sun The organohydrogenpolysiloxane used in the present invention functions as a crosslinking agent. This organohydrogenpolysiloxane is represented by the above formula (2) and has a hydrogen atom (ie, S
iH group) at least 2, and preferably 3 or more.

The molecular structure may be any of linear, branched, cyclic and three-dimensional networks, and a siloxane unit having a silicon-hydrogen bond [for example, HSiO _3/2 unit, R ³
(H) SiO _2/2 units, R ³ ₂ (H) SiO _1/2 units (wherein, R ³ is the same as R ³ of formula (2). Hereinafter, the same) in a polymer consisting] only, A siloxane unit having a silicon-hydrogen bond and a triorganosiloxy unit (R
^{₃ 3} SiO _1/2 units), diorganosiloxane units (R
³ ₂ SiO _2/2 units), or a copolymer of at least one selected from mono-organosiloxane units (R ³ SiO _3/2 units) and SiO _4/2 units. The viscosity is preferably about 3 to 120 cSt at 25 ° C.

In the formula (2), the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond represented by R ³ is the same as exemplified as R ^{1 in the} above formula (1). One. In consideration of the chemical stability and ease of synthesis of the obtained organohydrogenpolysiloxane, all of R ³ may be a methyl group, a combination of a methyl group and a phenyl group, or a combination of a methyl group and a tri group. It is preferred to select a combination of fluoropropyl groups. In the formula (2), c is 1.0 to 2.0, d is 0.04 to 1.0, and c + d is a number satisfying 1.1 to 2.5, preferably 1.9 to 2.3.

The organohydrogenpolysiloxane of the component (B) has an average number of silicon atoms (or degree of polymerization) of 4 to 120, preferably 4 to 100 in one molecule. If the number of silicon atoms in the molecule is too small, the volatility increases, which is not preferable. Conversely, if the number is too large, the viscosity of the composition becomes high and the fluidity deteriorates. These organohydrogenpolysiloxanes may be used alone or in combination of two or more.

Specific examples of the organohydrogenpolysiloxane of the component (B) include, for example, 1,3,
5,7-tetramethyltetracyclosiloxane, 1,3,5,7,8-
Siloxane oligomers such as pentamethylpentacyclosiloxane; trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends of molecular chain, dimethylsiloxane-methylhydrogensiloxane copolymer blocked at both ends of molecular chain trimethylsiloxy group, silanol group at both ends of molecular chain Methyl hydrogen polysiloxane, molecular chain both terminal silanol group-blocked dimethyl siloxane / methyl hydrogen siloxane copolymer, molecular chain both terminal dimethyl hydrogen siloxy group blocked dimethyl polysiloxane, molecular chain both terminal dimethyl hydrogen siloxy group blocked methyl hydro R, genpolysiloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, etc.
Consists of ³ ₂ (H) SiO _1/2 units and SiO _4/2 units,
Optionally, HSiO _3/2 units, R ³ ₃ SiO _1/2 units, R ³
₂ SiO _2/2 units, R ³ (H) SiO _2/2 units and R ³
A silicone resin that can contain at least one unit selected from SiO _3/2 units;

[0021]

Embedded image (Wherein, u and v are each an integer of 0 or 1 or more, and are integers satisfying u + v + 2 = 4 to 120),

[0022]

Embedded image (Wherein, w is an integer of 0 or 1 or more, x is an integer of 2 or more, and is an integer satisfying w + x + 2 = 4 to 120), and the like.

The amount of the component (B) used is such that, for each alkenyl group of the component (A) contained in the composition, a hydrogen atom (ie, a SiH group) bonded to a silicon atom of the component (B) is used.
The amount is 0.5 to 5, preferably 0.8 to 4. If the amount is too small, the mechanical strength of the cured product will deteriorate.If the amount is too large, the dehydrogenation reaction will proceed simultaneously with the hydrosilylation addition reaction to foam the composition at the time of curing. The mechanical strength of the cured product is reduced, and the physical properties of the obtained cured product are liable to change with time.

(C) Organopoieties Containing Silanol Groups
The organopolysiloxane of the component (C) used in the present invention reduces the sedimentation rate of the inorganic filler of the component (D) described below and reduces the sedimentation rate of the component (D) during storage. Has the effect of improving the redispersibility. This organopolysiloxane is represented by the formula (3), has an average of 2 to 300 silicon atoms in one molecule, and has at least one hydroxyl group (ie, a silanol group) bonded to the silicon atom, preferably Contains two or more.
The molecular structure may be linear, branched or cyclic. However, from the viewpoint of ease of synthesis, a linear one, particularly a diorganopolysiloxane in which both ends of the molecular chain are blocked with silanol groups, is preferable. The viscosity at 25 ° C. is 20
10001000 cSt, particularly preferably about 100-800 cSt.
Further, as the organopolysiloxane of the component (C),
20 or more silicon atoms, for example, 20 to 300, especially 4
It is preferably about 0 to 250, particularly about 80 to 250. If the number of silicon atoms is too small, the resulting composition may have thixotropic properties and the viscosity of the composition may increase. The silanol group-containing organopolysiloxane of the component (C) has a silicon atom in its molecule in view of the thixotropic property of the obtained composition and the impregnation property as a casting material for electric and electronic parts. Number (or degree of polymerization)
Is preferably equal to or more than the number of silicon atoms (or the degree of polymerization) in the molecule of the alkenyl group-containing organopolysiloxane of the component (A).

In the formula (3), R ⁴ is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group. As the unsubstituted or substituted monovalent hydrocarbon group, R ^{1 in the} above formula (1) Unsubstituted or substituted 1 which does not contain an aliphatic unsaturated bond
In addition to the valent hydrocarbon group, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group,
Usually, an alkenyl group having about 2 to 6 carbon atoms such as a pentenyl group, a hexenyl group and a cyclohexenyl group is exemplified. Further, in consideration of the chemical stability and the ease of synthesis of the obtained organopolysiloxane, all of R ⁴ may be a methyl group, a combination of a methyl group and a phenyl group, or a combination of a methyl group and a trifluoropropyl group. It is preferred to select a combination of groups. If necessary, a combination containing an addition-reactive functional group such as a combination of a methyl group and a vinyl group and a combination of a methyl group and a hydrogen atom may be selected.

That is, the component (C) comprises an addition-reactive functional group such as an alkenyl group bonded to a silicon atom (eg, a vinyl group) or a hydrogen atom bonded to a silicon atom (ie, an SiH group) in the molecule. When it is contained in the cured product, it is taken into the crosslinked structure together with the component (A) and the component (B) at the time of curing. A decrease in strength can be effectively prevented.

In the formula (3), e is 1.0 to 2.5, preferably
It is a number between 1.5 and 2.2. If e is less than 1.0, the synthesis of the organopolysiloxane becomes difficult, and the fluidity of the composition becomes poor. If e is greater than 2.5, the required amount of silanol groups cannot be obtained. In the equation (3), f is a positive number equal to or less than 1;
It is usually a positive number from 0.003 to 1, especially from 0.01 to 0.5, and is selected so that at least one, preferably at least two, hydroxyl groups (silanol groups) bonded to a silicon atom are present in one molecule. When f is greater than 1, the synthesis of the organopolysiloxane becomes difficult, and the thixotropic property becomes strong, so that the fluidity of the composition decreases.

The organopolysiloxane of component (C) has an average of 2 to 300, preferably 40 to 25, per molecule.
It has a silicon atom number (or degree of polymerization) of about 0, especially about 80 to 250, and if the silicon atom number is too small, the resulting organopolysiloxane becomes unstable and is difficult to handle. On the other hand, if the amount is too large, the amount of the organopolysiloxane used becomes large in order to obtain desired effects, for example, an effect of improving the redispersibility of the inorganic filler of the component (D), and the fluidity of the composition is increased. Decrease.

The amount of the component (C) used depends on the amount of the component (A)
And 100 to 100 parts by weight of the total amount of component (B) and 0.01 to 0.5
Parts by weight . If this usage is too low, for example,
The effect of improving the redispersibility of the inorganic filler as the component (D) cannot be obtained. Conversely, if it is too large, it acts as a plasticizer, and the mechanical strength of the cured product decreases.

When an organopolysiloxane containing an alkenyl group or a hydrogen atom is used as R ⁴ ,
For each alkenyl group bonded to a silicon atom in the entire composition (for example, an alkenyl group bonded to a silicon atom in component (A) or in components (A) and (C)), hydrogen bonded to a silicon atom It is necessary to adjust the amount of component (B) to be used so that the number of atoms (for example, hydrogen atoms bonded to silicon atoms in component (B) or component (B) and component (C)) is 0.5 to 5. There is.

(D) Inorganic Filler The inorganic filler used in the present invention not only reduces the cost of the composition obtained, but also lowers the coefficient of thermal expansion of a cured product of the composition, and has good heat dissipation and poor heat dissipation. Has the effect of improving flammability. The average particle diameter of the inorganic filler used in the present invention is 1 to 50 μm, preferably 2 to 35 μm, more preferably 3 to 30 μm. If the average particle size is too small, the fluidity of the composition will decrease. On the contrary, if it is too large,
Since the sedimentation speed of the inorganic filler in the composition is increased, the resulting cured product becomes inhomogeneous and the mechanical strength is reduced. Further, the wear of the equipment used to prepare the composition becomes severe.

Examples of the inorganic filler used in the present invention include crystalline silica, fused silica, diatomaceous earth, zirconium silicate, alumina, and aluminum hydroxide. Among them, crystalline silica, alumina, or a mixture thereof is preferable in consideration of achieving low cost and thermal conductivity (heat dissipation).

The amount of the component (D) used depends on the amount of the component (A),
It is 50 to 350 parts by weight, preferably 80 to 300 parts by weight, per 100 parts by weight of the total amount of the components (B) and (C). If the amount is too small, the effects of low expansion coefficient, improvement of heat dissipation and flame retardancy, or reduction of the cost of the composition cannot be sufficiently obtained, and if it is too large, the fluidity of the composition deteriorates. The mechanical strength of the cured product decreases.

(E) Platinum or Platinum Compound Platinum or a platinum compound used in the present invention is a catalyst for promoting a hydroxylation reaction, and a known one can be used. Specific examples of platinum or platinum compounds include, for example, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum-olefin complex, platinum-aldehyde complex, platinum-vinylsiloxane complex, platinum-acetylene alcohol And the like.

The amount of platinum or platinum compound to be used is a so-called catalytic amount and can be appropriately adjusted according to the desired curing rate of the composition. Usually, the amount of platinum atom relative to the weight of component (A) It may be about 0.5 to 500 ppm by weight, preferably 1 to 300 ppm. If the amount is too small, the composition may be insufficiently cured. Conversely, if the amount is too large, the hydroxylation reaction proceeds rapidly, which shortens the pot life and is uneconomical.

Other Components In addition to the above components (A) to (E), the composition of the present invention may contain, if necessary, within a range not to impair the object of the present invention.
Reinforcing fillers, pigments, heat resistance improvers, flame retardant improvers, reaction control agents, plasticizers and the like can be added.

As the above-mentioned reinforcing filler, for example,
(R ⁵ ) ₃ SiO _1/2 units [where R ⁵ is ¹ of the above R 1
It is the same monovalent hydrocarbon group as the monovalent hydrocarbon group. The same applies to the following.], _Which essentially consists of CH ₂ ＣＨCH (R ⁵ ) ₂ SiO _1/2 units and SiO _4/2 units, and (R ⁵ ) ₃ SiO _1/2 units for SiO _4/2 units and (CH ₂ = CH)
Resin-like organopolysiloxane copolymers having a total molar ratio of (R ⁵ ) ₂ SiO _1/2 units of 0.5 to 1 and 2.5 to 10 mol% of all silicon atoms having a vinyl group, etc. No.

Examples of the above-mentioned pigments include iron oxide, carbon black, titanium oxide, zinc oxide and the like. Examples of the heat resistance improver include iron oxide, zirconium silicate, titanium oxide, cerium oxide, cerium hydroxide, and carbon black. Examples of the flame retardant improver include fumed titanium oxide, cerium oxide, cerium hydroxide, zinc carbonate, manganese carbonate, carbon black, benzotriazole and the like.

Examples of the reaction control agent include vinyl siloxane, acetylene alcohols, silane or siloxane containing an ethynyl group, triallyl isocyanurate and the like. Examples of the plasticizer include inert dimethylpolysiloxane.
When imparting adhesiveness to the composition of the present invention, an adhesion aid may be added to the composition.

The above-mentioned components (hereinafter, referred to as desired components) other than the components (A) to (E) can be used alone or in combination of two or more. In addition, when the desired component is added to the composition, for example, a vinyl group-containing silicone resin (that is, the (R ⁵ ) ₃ SiO
_1/2 unit, (CH ₂ ＣＨCH) (R ⁵ ) ₂ SiO _1/2 unit, copolymer composed of SiO _4/2 unit), vinyl siloxane, adhesion aid containing hydrogen atom bonded to silicon atom When a component containing an alkenyl group bonded to a silicon atom or a hydrogen atom bonded to a silicon atom, such as the above, is added to the composition, one alkenyl group bonded to the silicon atom in the composition after the addition is added. It is necessary to add the above-mentioned desired components in such an amount that the number of hydrogen atoms directly bonded to silicon atoms becomes 0.5 to 5.

Organopolysiloxane Composition for Electrical Insulation The composition of the present invention can be easily obtained by uniformly mixing the above components. In mixing the components, the component (A) and the component (B) undergo a hydrosilylation reaction in the presence of the component (E). Curing starts. Therefore, it is preferable to store these components in at least two packages. As a specific example of the preservation method, for example, a part of the component (A), a part of the component (C), a part of the component (D) and a whole of the component (E) are packaged, The balance of component (A), the balance of component (C),
There is a method in which the rest of the component (D) and all of the component (B) are packaged in another package. If you use this method,
It is preferred that component (D) be distributed in each package such that the specific gravity of the composition in the package is equal. In another embodiment of the storage method, a part of the component (A) to be blended, all of the component (C), all of the component (D), and all of the component (E) are packaged, and the component ( There is a method in which the remainder of A) and all of the component (B) are packaged in another package. Each component separated into these two packages may be mixed in a prescribed amount by an appropriate method at the time of use. The composition of the present invention can be stored in one package by blending any one of acetylene alcohols and triallylisocyanurates as a reaction control agent.

The composition of the present invention may be used in an electric or
In general, the composition is directly cast into a container containing electronic components, or the components are filled by impregnating the components and then cured. The curing of the composition proceeds at room temperature, but is accelerated by heating. The heating temperature may be about 100 ° C., and an appropriate temperature of 100 ° C. or more can be selected.

[0043]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to the following examples. In this example, parts represent parts by weight,
The viscosity is a value measured at 25 ° C.

Example 1 CH ₂ = CH (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₁₄₅ Si (CH ₃ ) ₂ CH = CH ₂ , having a viscosity of 400 cSt at both ends of a molecular chain Is a methyl group represented by the following formula: (CH ₃ ) ₃ SiO [(CH ₃ ) HSiO] ₇ [(CH ₃ ) ₂ SiO] ₈ Si (CH ₃ ) ₃ 35 parts of genpolysiloxane,
The following formula: HO (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₂₀₀ Si (CH ₃ ) ₂ OH, 2.5 parts of dimethylpolysiloxane having a viscosity of 700 cSt and terminated at both molecular chains by silanol groups, 1000 parts of crystalline silica powder having an average particle size of 30 μm and 2.0 parts of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane were charged into a vessel equipped with a vacuum pump and a stirrer. ,
Mix under reduced pressure. The obtained mixture is hereinafter referred to as mixture A. Next, 1000 parts of the mixture A was filled in a metal round can having a capacity of 1 L and allowed to stand for 3 months. Then, the mixture A was mixed with a metal spatula. Evaluation was based on criteria. Table 1 shows the results. Easy: easy stirring with a spatula. Difficulty: The precipitate could be redispersed by grinding with a spatula, but it took a long time. Very difficult: The precipitate was hard and could not be redispersed with a spatula.

Then, 2-9.9 parts of chloroplatinic acid was added to 299.9 parts of the mixture A.
Ethyl hexanol modified solution (platinum concentration 2% by weight) 0.1
The mixture was added and mixed to prepare Composition A. Table 2 shows the initial viscosity and specific gravity of the composition A. Next, the composition A is heated at 100 ° C.
The composition was cured by heating for 30 minutes, and the following physical properties of the cured product were evaluated. No foaming was observed during curing. Table 2 shows the results.

(Hardness) The hardness was measured in accordance with JIS K6301. The tester was a spring type hardness tester A.
A mold was used. (Volume resistivity) The volume resistivity was measured in accordance with the method defined in JIS C 2123 (test method for silicone rubber compound for electricity). (Dielectric breakdown strength) It was measured in accordance with the method specified in JIS C 2123 (test method for silicone rubber compound for electric use). (Dielectric constant [1 MHz]) The dielectric constant was measured in accordance with the method specified in JIS C 2123 (test method for silicone rubber compound for electric use). (Dielectric loss tangent [1 MHz]) It was measured according to the method specified in JIS C 2123 (test method for silicone rubber compound for electricity). (Flame retardancy) Measured according to the method specified in UL94.

Comparative Example 1 A mixture B was prepared in the same manner as in Example 1 except that 2.5 parts of dimethylpolysiloxane terminated at both ends of the molecular chain with a silanol group was not used. Next, 1000 parts of the mixture B was filled into a metal can having a capacity of 1 L, and the difficulty of re-dispersion of the sediment was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 2 The following formula: CH ₂ = CH (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₁₈₀ Si (CH ₃ ) ₂ CH = CH ₂ Both ends of a molecular chain having a viscosity of 600 cSt Is 455 parts of dimethylpolysiloxane terminated with a vinyl group, and methylhydrogen represented by the following formula: (CH ₃ ) ₃ SiO [(CH ₃ ) HSiO] ₃₀ [(CH ₃ ) ₂ SiO] ₅₀ Si (CH ₃ ) ₃ 40 parts of genpolysiloxane,
The following formula: HO (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₂₀₀ Si (CH ₃ ) ₂ OH, having a viscosity of 700 cSt and 1.5 parts of dimethylpolysiloxane terminated at both molecular chain ends with silanol groups, 750 parts of crystalline silica powder having an average particle diameter of 5 μm and 3.0 parts of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane were charged into a vessel equipped with a vacuum pump and a stirrer, Mix under reduced pressure. The obtained mixture is hereinafter referred to as mixture C. Next, 1000 parts of the mixture C was filled in a metal round can having a capacity of 1 L, and the difficulty of re-dispersion of the sediment was evaluated in the same manner as in Example 1. Table 1 shows the results.

In Example 1, the mixture A299.9
A composition C was prepared in the same manner as the composition A of Example 1, except that 249.9 parts of the mixture C was used instead of parts. Table 2 shows the initial viscosity and specific gravity of the composition C. Next, the composition C was cured in the same manner as in Example 1, and the physical properties of the cured product were evaluated in the same manner as in Example 1. Table 2 shows the results.
No foaming was observed during curing.

Comparative Example 2 A mixture D was prepared in the same manner as in Example 2 except that 1.5 parts of dimethylpolysiloxane terminated with silanol groups at both ends of the molecular chain was not used. Next, 1000 parts of the mixture D was filled in a metal can having a capacity of 1 L, and the difficulty of re-dispersion of the sediment was evaluated in the same manner as in Example 2. Table 1 shows the results.

Example 3 CH ₂ = CH (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₁₄₅ Si (CH ₃ ) ₂ CH = CH ₂ , having a viscosity of 400 cSt at both ends of a molecular chain Is a dimethylpolysiloxane terminated with a vinyl group, represented by the following formula: CH ₂ = CH (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₆₅ Si (CH ₃ ) ₂ CH = CH ₂ 90 parts of 100 cSt dimethylpolysiloxane terminated at both molecular chain ends with vinyl groups, the following formula: (CH ₃ ) ₃ SiO [(CH ₃ ) HSiO] ₇ [(CH ₃ ) ₂ SiO] ₈ Si (CH ₃ ) ₃ 45 parts of methyl hydrogen polysiloxane represented by
The following formula: HO (CH ₃ ) ₂ SiO [(CH ₃ ) ₂ SiO] ₂₀₀ Si (CH ₃ ) ₂ OH, having a viscosity of 700 cSt and having both ends of a molecular chain terminated with silanol groups, 2.0 parts of dimethylpolysiloxane, 500 parts of crystalline silica powder having an average particle diameter of 5 μm, 450 parts of α-alumina powder having an average particle diameter of 16 μm, and 1,3,5,7-tetramethyl-1,
2.5 parts of 3,5,7-tetravinylcyclotetrasiloxane was charged into a container equipped with a vacuum pump and a stirrer, and mixed under reduced pressure. The obtained mixture is hereinafter referred to as mixture E. next,
1000 parts of the mixture E was filled into a metal can having a capacity of 1 L, and the difficulty of re-dispersion of the sediment was evaluated in the same manner as in Example 1. Table 1 shows the results.

Further, in Example 1, mixture A299.9
Composition E was prepared in the same manner as composition A of Example 1, except that 289.9 parts of mixture E was used instead of parts. Table 2 shows the initial viscosity and specific gravity of the composition E. Next, the composition E was cured in the same manner as in Example 1, and the physical properties of the cured product were evaluated in the same manner as in Example 1. Table 2 shows the results.
No foaming was observed during curing.

Comparative Example 3 A mixture F was prepared in the same manner as in Example 3 except that 2.0 parts of dimethylpolysiloxane in which both ends of the molecular chain were terminated with silanol groups were not used. Next, 1000 parts of the mixture F was filled into a metal round can having a capacity of 1 L, and the difficulty of re-dispersion of the sediment was evaluated in the same manner as in Example 3. Table 1 shows the results.

[0054]

[Table 1]

[0055]

[Table 2] In Table 2, V-0 represents the flame retardancy level in the measurement method specified in UL94.

[0056]

The composition of the present invention has good fluidity, and can easily and easily redisperse the inorganic filler deposited on the bottom of the container during storage. The cured product of the composition of the present invention not only has excellent heat dissipation, low heat, and expandability, but also has excellent electrical properties and flame retardancy, and can reduce the cost of the composition.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 83:06) C08L 83:06) (72) Inventor Hironao Fujiki 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture 10 Shin-Etsu Chemical Co., Ltd. Silicone (56) References JP-A-6-256658 (JP, A) JP-A-58-219034 (JP, A) JP-A-55-58253 (JP, A) JP-A 52-14654 (JP, A) JP-A-6-52720 (JP, A) JP-A-8-325457 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/00-83 / 16 C08K 3/00-13/08 H01B 3/46

Claims (2)

(57) [Claims] (A) General composition formula (1): R ¹ _a R ² _b SiO _{(4-ab) / 2} (1) (wherein R ¹ independently represents a non-unsaturated non-unsaturated bond. A substituted or substituted monovalent hydrocarbon group, R ² is an alkenyl group, a is 1.5 to 2.0, b is 0.003 to 0.5, and a + b is a number satisfying a + b = 2.00 to 2.07)
An organopolysiloxane having an average of 30 to 600 silicon atoms in one molecule and containing at least two alkenyl groups bonded to the silicon atoms, (B) a general composition formula (2): R ³ _c H _d SiO _{(4-cd) / 2} (2) (wherein, R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, and c is 1.0 to 2.0 And d is 0.04 to 1.0, and c + d = 1.1 to 2.5
Which satisfies
An organohydrogenpolysiloxane having from to 120 silicon atoms and containing at least two hydrogen atoms bonded to silicon atoms; one alkenyl group in component (A) and silicon in component (B) the amount of hydrogen atoms bonded to atoms of 0.5 to five, (C) the general formula _{^{(3) R 4 e (OH}} ) f SiO (4-ef) / 2 (3) ( wherein, R ⁴ is independently Is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, e is 1.0 to 2.5, and f is a positive number of 1 or less. An organopolysiloxane having at least one hydroxyl group bonded to a silicon atom having at least one silicon atom; 0.01 to 0.5 parts by weight based on 100 parts by weight of the total of the components (A) and (B); Inorganic filler having an average particle size of 1 to 50 μm ( however, flat
Spherical or non-spherical alumina fine particles having a uniform particle size of less than 10 μm
5 to 95% by weight of powder and spherical with average particle size of 10 to 50 μm
Or aluminum consisting of 95 to 5% by weight of non-spherical alumina fine powder
( Excluding fine powder ); essentially contains 30 to 350 parts by weight and (E) a catalytic amount of platinum or a platinum compound, based on 100 parts by weight of the total of components (A), (B) and (C). Non-foamable organopolysiloxane composition for electrical insulation. 2. The composition according to claim 1, wherein the organopolysiloxane of the component (C) has 20 or more silicon atoms.