JP2010047678A - Polyorganosiloxane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an addition reaction curing type polyorganosiloxane composition that excels in fluidity before curing and shows low moisture permeability after curing. <P>SOLUTION: The polyorganosiloxane composition comprises: (A) 100 pts.wt. of an alkenyl group-containing polyorganosiloxane that contains two or more silicon atom-bound alkenyl groups in the molecule and has a viscosity of 0.1-1,000 Pa s at 23°C; (B) a polyorganohydrogensiloxane having, in the molecule, silicon atom-bound hydrogen atoms of a number exceeding two on the average in such an amount that the number of the silicon atom-bound hydrogens makes 0.5-5.0 to one alkenyl group present in the (A); (C) a platinum group metal compound in such an amount that the platinum group metal atom makes 0.1-1,000 wt.ppm to the amount of the (A); and (D) a product obtained by mixing (D1) mica powder, (D2) an organoalkoxysilane represented by formula (IV) and (D3) an aluminum chelate compound (wherein, based on 100 wt.% of (D1), (D2) is 0.1-10 wt.% and (D3) is 0.05-5 wt.%) in such an amount as for the (D1) to make 20-200 pts.wt. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an addition reaction curable polyorganosiloxane composition, and more particularly to an addition reaction curable polyorganosiloxane composition that has excellent fluidity before curing and exhibits low moisture permeability after curing.

  Addition reaction curable polyorganosiloxane compositions can be cured in a short time by heating and do not generate by-products, making them suitable for applications such as sealing materials, sealants, protective materials, and insulating materials for electronic components. Widely used. However, the cured products of these compositions generally have a large moisture permeability due to a large gap between molecular chains, and there are cases in which application to uses that hate moisture is difficult.

In order to reduce moisture permeability, attempts have been made to add an inorganic filler to the addition reaction curable polyorganosiloxane composition (for example, Patent Document 1), but the viscosity can be increased by adding an inorganic filler. As a result, there is a problem that it becomes difficult to use in applications where low viscosity and high fluidity are required for work.
JP 2005-8657 A

  An object of the present invention is to provide an addition reaction curable polyorganosiloxane composition which is excellent in fluidity before curing and exhibits low moisture permeability after curing.

  The present inventor can solve the problem by blending a product obtained by mixing mica powder, a specific organoalkoxysilane and an aluminum chelate compound with an addition reaction curable polyorganosiloxane composition. As a result, the present invention has been completed.

That is, the present invention
(A) 100 parts by weight of an alkenyl group-containing polyorganosiloxane containing two or more alkenyl groups bonded to silicon atoms in the molecule and having a viscosity at 23 ° C. of 0.1 to 1,000 Pa · s;
(B) A hydrogen bonded to a silicon atom with respect to one alkenyl group present in (A), a polyorganohydrogensiloxane bonded to a silicon atom and having an average of more than two hydrogen atoms in the molecule. An amount in which the number of atoms is 0.5 to 5.0;
(C) An amount of platinum group metal compound in which the platinum group metal atom is 0.1 to 1,000 ppm by weight with respect to the amount of (A); and (D) (D1) mica powder and (D2 Formula (IV):
R ¹⁰ _p Si (OR ¹¹ ) _4-p (IV)
(In the formula, R ¹⁰ is a C ₁ -C ₁₈ alkyl group, a C ₃ -C ₁₈ cycloalkyl group or an aryl group, R ¹¹ is a C ₁ -C ₆ alkyl group, and p is 0-3. A product obtained by mixing (D3) an aluminum chelate compound (wherein (D1) is 100% by weight and (D2) is 0.1 to 0.1%) A polyorganosiloxane composition comprising an amount of 10% by weight and (D3 is 0.05-5% by weight), wherein (D1) is 20-200 parts by weight. The present invention relates to a hard disk or a display device having a protective layer obtained by curing.

  The present invention provides an addition reaction curable polyorganosiloxane composition that is excellent in fluidity before curing and exhibits low moisture permeability after curing. The polyorganosiloxane composition of the present invention is useful for moisture-sensitive materials, particularly protective layers for electronic parts, hard disks, display devices, seals, gaskets, and the like.

  The alkenyl group-containing polyorganosiloxane of the component (A) in the present invention is a component that becomes a base polymer in the polyorganosiloxane composition of the present invention. This component (A) contains two or more alkenyl groups bonded to a silicon atom in one molecule, and can form a network structure by addition reaction with the Si—H bond of component (B). Anything is acceptable.

Typically, formula (I):
(R ¹ ) _a (R ² ) _b SiO _{(4-ab) / 2} (I)
(Where
R ¹ represents an alkenyl group;
R ² represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated carbon-carbon bond;
a is 1 or 2;
b is an integer of 0 to 2, provided that a + b is 2 or 3.
And an alkenyl group-containing polyorganosiloxane having at least two alkenyl group-containing siloxane units in the molecule.

Examples of R ^{1 in} formula (I) include vinyl, allyl, 3-butenyl, 5-hexenyl and the like. The vinyl group is most preferable because it is easy to synthesize and does not impair the fluidity of the composition before curing and the heat resistance of the composition after curing. a is preferably 1 because it is easy to synthesize.

Examples of the organic group bonded to the silicon atom of R ^{2 of the} formula (I) and other siloxane units in the component (A) include alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl. A cycloalkyl group such as cyclohexyl; an aryl group such as phenyl; an aralkyl group such as 2-phenylethyl and 2-phenylpropyl; chloromethyl, chlorophenyl, 2-cyanoethyl, 3,3,3-trifluoropropyl And a hydrocarbon group substituted with a substituent such as a halogen or a cyano group. A phenyl group is preferable from the viewpoint of a decrease in moisture permeability, and a methyl group is preferable from the viewpoint of easy synthesis and excellent balance of properties such as mechanical strength and fluidity before curing. Of the organic groups bonded to the silicon atoms of the other siloxane units in R ² and the component (A) in the formula (I), it is preferable that 15 mol% or more is a phenyl group, more preferably 20 to 80 mol%. Is a phenyl group. In these cases, a methyl group other than the phenyl group is particularly preferred.

  Specifically, the formula (II):

(Where
R is independently R ³ or R ⁴ , at least two of R are R ³ ,
R ³ is independently a C ₂ -C ₆ alkenyl group,
R ⁴ is independently a C ₁ -C ₆ alkyl group or a phenyl group, and among R ⁴ , 15 mol% or more is a phenyl group,
m represents a linear polyorganosiloxane represented by (A) having a viscosity at 23 ° C. of 0.1 to 1,000 Pa · s). R ³ is preferably a vinyl group, R ⁴ is a methyl group or a phenyl group, and 20 to 80% of R ⁴ is a linear polyorganosiloxane of the formula (II).

  The alkenyl group-containing polyorganosiloxane is preferably heat-treated at 180 ° C. for 8 to 72 hours in the presence of oxygen. This treatment usually increases the viscosity in the range up to about twice the initial value.

  The viscosity of component (A) at 23 ° C. is in the range of 0.1 to 1,000 Pa · s. The lower limit of the viscosity at 23 ° C. is preferably 0.2 Pa · s, and more preferably 0.3 Pa · s. The upper limit is preferably 500 Pa · s, more preferably 200 Pa · s.

  The siloxane skeleton of component (A) may be linear or branched, and both may be used together. Since it is easy to control the synthesis and the average degree of polymerization, the component (A) is preferably linear, and when it is necessary to give excellent mechanical properties to the composition after curing, the component (A) In the range of up to 20% by weight, it is more preferable to use a branched one in combination.

  As the component (A), one type may be used, or two or more types may be used in combination. In the latter case, the viscosity means the viscosity of the mixed alkenyl group-containing polyorganosiloxane.

  The polyorganohydrogensiloxane of the component (B) in the present invention is used as a crosslinking agent of the component (A) by the addition reaction of the Si—H bond in the molecule with the alkenyl group in the component (A). It functions. In order to reticulate the cured product, the component (B) has an average of more than 2, preferably 3 or more hydrogen atoms bonded to silicon atoms in the molecule.

The component (B) is typically represented by the general formula (III):
(R ⁵ ) _c H _d SiO _{(4-cd) / 2} (III)
(Where
R ⁵ represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated carbon-carbon bond;
c is an integer from 0 to 2;
d is 1 or 2, provided that c + d is an integer of 1 to 3)
The number of units in the molecule is more than 2 on average, preferably 3 or more.

Examples of R ^{5 in} formula (III) are the same as those for R ^{2 in the} component (A) described above, and among them, a methyl group is most preferable from the viewpoint of easy synthesis. Further, d is preferably 1 because synthesis is easy.

  The siloxane skeleton in the component (B) may be linear, branched or cyclic. As the component (B), one type may be used, or two or more types may be used in combination.

  The degree of polymerization of the component (B) is not particularly limited, but a polyorganohydrogensiloxane in which two or more hydrogen atoms are bonded to the same silicon atom is difficult to synthesize, and therefore preferably comprises three or more siloxane units. The number of siloxane units is more preferably 6 to 200, and particularly preferably 10 to 150, since it does not volatilize even when heated to the curing temperature, and is excellent in fluidity and easily mixed with the component (A).

  The platinum group metal compound of component (C) in the present invention is a catalyst for promoting the addition reaction between the alkenyl group in component (A) and the hydrosilyl group in component (B). As the platinum group metal compound, a compound of a platinum group metal atom such as platinum, rhodium, palladium is used, and chloroplatinic acid, a reaction product of chloroplatinic acid and an alcohol, a platinum-olefin complex, a platinum-vinylsiloxane complex, Examples include platinum compounds such as platinum-ketone complexes and platinum-phosphine complexes; rhodium compounds such as rhodium-phosphine complexes and rhodium-sulfide complexes; palladium compounds such as palladium-phosphine complexes.

  Of these, the reaction product of chloroplatinic acid and alcohol and a platinum-vinylsiloxane complex are preferred because of their good catalytic activity. When it is necessary to cure in a short time and develop adhesiveness, platinum- 1,1,3,3-tetramethyl-1,3-divinyldisiloxane complex is particularly preferred.

  The component (D) in the present invention is a product obtained by mixing the mica powder (D1), the organoalkoxysilane (D2), and the (D3) aluminum chelate compound. By mix | blending (D) component with a composition, the fluidity | liquidity before hardening can be improved, maintaining the low moisture permeability after hardening. In mixing the components (D1) to (D3), the component (D2) functions as a surface treatment agent for the component (D1), and the component (D3) functions as an accelerator for the surface treatment. It is considered that the component (D) having a good affinity for is obtained, and by adding this, the composition has improved fluidity.

  The component (D1) mica powder is a component that contributes to reducing the moisture permeability of the cured composition. In terms of moisture permeability reduction and moldability, the component (D1) preferably has an average particle size of 1 to 100 μm, more preferably 1 to 60 μm. Examples of the component (D1) include natural mica such as muscovite, phlogopite, biotite, and synthetic mica. Mica is preferred because it has few impurities and gives excellent mechanical properties to the cured composition. These mica are generally flat powders, and the average particle size refers to the maximum diameter of the flat surface.

The (D2) component organoalkoxysilane has the formula (IV):
R ¹⁰ _p Si (OR ¹¹ ) _4-p (IV)
(In the formula, R ¹⁰ is a C ₁ -C ₁₈ alkyl group, a C ₃ -C ₁₈ cycloalkyl group or an aryl group, R ¹¹ is a C ₁ -C ₆ alkyl group, and p is 0-3. Is an integer). If R ¹⁰ is more, there are also respectively identical, but may be different, preferably the same. When there are a plurality of R ^{11 s} , they may be the same or different, but are preferably the same.

When R ^{10 in} formula (IV) is a C ₁ -C ₁₈ alkyl group, examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, and in the case of a C ₃ -C ₁₈ cycloalkyl group, Examples include cyclohexyl and, in the case of an aryl group, phenyl. C ₁ -C ₁₀ alkyl group is preferred from the viewpoint of ease of synthesis and excellent balance of mechanical strength characteristics. R ^{11 in the} formula (IV) is a C ₁ -C ₆ alkyl group, and examples thereof include methyl, ethyl, propyl, butyl, pentyl and hexyl, preferably methyl, ethyl and propyl. p is an integer of 0 to 3, preferably 0 or 1.

  Examples of the component (D2) include methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, dimethyldiethoxysilane, and the like. From the viewpoint of safety, reactivity, and affinity with the component (D1), tetraethoxysilane and methyltrimethoxysilane are preferred.

  As the aluminum chelate compound of component (D3), aluminum ethyl acetoacetate / diisopropylate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate, aluminum bisethylacetoacetate / monoacetylacetonate, aluminum alkylacetoacetate / di Examples thereof include isopropylate and aluminum alkenyl acetoacetate diisopropylate. Aluminum alkyl acetoacetate diisopropylate and aluminum alkenyl acetoacetate diisopropylate are preferable from the viewpoint of legal restrictions and reactivity, and examples thereof include those having 8 to 24 carbon atoms in the alkyl group or alkenyl group. Specifically, the formula (V):

An aluminum chelate compound [CAS No. 80481-35-2].

In the compositions of the present invention, the amount of component (B) is, (A) the ratio of hydrogen atoms bonded to silicon atoms of component (B) to the R ¹ group in the component (H / Vi), 0. The amount is 5 to 5.0, preferably 0.8 to 3.0. (C) The compounding quantity of component is 0.1-1,000 weight ppm normally in conversion of a platinum group metal atom with respect to the total amount of (A) component and (B) component, Preferably 0.5- 200 ppm by weight.

  Component (D1) is 20 to 200 parts by weight, preferably 40 to 200 parts by weight, based on 100 parts by weight of component (A), from the viewpoint of reducing moisture permeability. The component (D2) is an amount of 0.1 to 10% by weight when the component (D1) is 100% by weight, and the component (D3) is when the component (D1) is 100% by weight. , 0.01 to 5% by weight. By mixing the component (D1), the component (D2), and the component (D3) in such an amount, the component (D1) can be surface-treated efficiently and effectively. The component (D2) is preferably 0.5 to 5% by weight, and the component (D3) is preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight.

  The component (D) is obtained by mixing the component (D1), the component (D2), and the component (D3). Mixing can be performed in the presence of the component (A). For example, after the component (D1) is dispersed in the component (A), the component (D2) and the component (D3) are blended, and a universal kneader, kneader It can be uniformly kneaded by a mixing means such as. In mixing, a diluent can be appropriately used. Examples of the diluent include silicone oil, and phenyl group-containing silicone oil is particularly preferable.

  The mixing can be performed, for example, in an inert atmosphere (for example, in a nitrogen atmosphere) at 20 to 120 ° C. for 1 to 36 hours, but from the viewpoint of securing fluidity, under heating at 80 to 120 ° C. Preferably it is done. In the case of mixing under heating, a sufficient effect can be obtained even for 1 to 8 hours.

  The composition of the present invention can be prepared by blending the component (D) with the components (A), (B) and (C), and other optional components blended as necessary. In order to stably store for a long period of time, with respect to the (B) component and the (C) component, the (A) component is appropriately distributed and stored in two containers so that it becomes a separate container, They may be mixed immediately before use and degassed under reduced pressure for use.

  Examples of the optional component include an adhesiveness imparting agent for imparting adhesiveness. Examples of the adhesion-imparting agent include 3-glycidoxypropyl group-containing alkoxy such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyl (methyl) dimethoxysilane. Silanes; 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl (methyl) dimethoxysilane Such 2- (3,4-epoxycyclohexyl) ethyl group-containing alkoxysilanes; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, methylvinyldimethoxysilane, allyltrimethoxysilane, allyltri Ethoxy Alkenylalkoxysilanes such as methyl and allyldimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyl (methyl) dimethoxysilane, 3-methacryloxypropyltrimethoxy (Meth) acryloxypropylalkoxysilanes such as silane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyl (methyl) dimethoxysilane; hydrogen atoms bonded to silicon atoms and the following general bonds bonded to silicon atoms Formula (VI):

(Wherein Q ¹ represents a linear or branched alkylene group forming a carbon chain having two or more carbon atoms between a silicon atom and an ester bond; Q ² represents an oxygen atom and a side. Represents a linear or branched alkylene group which forms a carbon chain having 3 or more carbon atoms between silicon atoms in the chain; R ²⁰ represents an unsubstituted or substituted alkyl group having 1 to 6 carbon atoms; An aluminum alkoxide such as aluminum triethoxide, aluminum tripropoxide, aluminum tributoxide; titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, Titanium alkoxides such as titanium tetrabutoxide, titanium tetraisobutoxide, titanium tetraisopropenyl oxide; Tetra isopropoxide, zirconium alkoxides such as zirconium tetrabutoxide; diallyl maleate, polar group-containing organic compounds such as triallyl isocyanate, and the like are exemplified.

In the side chain represented by the general formula (VI), Q ¹ is exemplified by an alkylene group such as ethylene, trimethylene, 2-methylethylene, tetramethylene, and the like. -A methylethylene group is preferred. Examples of Q ² include an alkylene group such as trimethylene, 2-methyltrimethylene, and tetramethylene, and a trimethylene group is preferable because synthesis and handling are easy. Examples of R ²⁰ include alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl; and alkyl groups substituted with alkoxy such as 2-methoxyethyl, which give good adhesion and are alcohols produced by hydrolysis Are easy to volatilize, a methyl group and an ethyl group are preferable, and a methyl group is particularly preferable. As an organosilicon compound having such a side chain, the following formula:

The siloxane compound shown by these is illustrated. The compounding amount of the adhesion-imparting agent varies depending on the kind of the adhesion-imparting agent and the substrate, but is usually in the range of 0.5 to 20 parts by weight with respect to 100 parts by weight of the component (A), and particularly to the substrate. 2-20 parts by weight is preferable, and 3-15 parts by weight is more preferable.

  Further, as an optional component, there may be mentioned a curing inhibitor for suppressing the curing reaction and improving the storage stability and workability of the uncured composition. The diallyl maleate is also effective as a curing inhibitor. In addition, as the curing inhibitor, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl- Acetylene alcohols such as 1-cyclohexane-1-ol are exemplified.

  Furthermore, the composition of the present invention includes a diluent, a pigment, a thixotropy imparting agent, a viscosity modifier for improving extrusion workability, an ultraviolet ray inhibitor, a fungicide, a heat resistance improver, depending on the purpose. Various additives such as a flame retardant may be added. Depending on the application, the composition of the present invention may be dissolved or dispersed in an organic solvent such as toluene or xylene.

  The composition of the present invention is attached to a processing object by a method such as injection, dripping, casting, casting, extrusion molding, or by integral molding by transfer molding or injection molding, and is heated and cured, Silicone rubber can be obtained. Curing conditions can be set as appropriate depending on the type and amount of component (C), for example, a temperature between 20 and 250 ° C., but usually between 100 and 150 ° C. for 30 minutes to 4 hours. is there.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In these examples, parts indicate parts by weight, and the viscosity indicates the viscosity at 23 ° C. The present invention is not limited by these examples.

Each component of the examples and comparative examples is as follows. Siloxane units are indicated by the following symbols.
M Unit: (CH ₃ ) ₃ SiO _1/2 −
M ^H unit: (CH ₃ ) ₂ HSiO _1/2 −
M ^v unit: (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 −
D Unit: - (CH _{3) 2} SiO-
D ^H units: - (CH ₃₎ HSiO-
D ^ff _{Unit: - (C 6 H 5)} 2 HSiO-
Q unit: SiO _4/2 (tetrafunctional)

A-1: A straight-chain polymethylvinylsiloxane having both ends blocked with ^Mv units, all intermediate units consisting of D units, and a viscosity at 23 ° C. of 3 Pa · s is obtained at 180 ° C. for 8 hours in the air. Stirred siloxane (viscosity increased to 1.5 times the initial value)
A-2: A linear polymethylvinylsiloxane having both ends blocked with ^Mv units, an intermediate unit ^{consisting of} 60 mol% D units and 40 mol% ^Dff units, and a viscosity at 23 ° C of 3 Pa · s. The siloxane was stirred for 24 hours at 180 ° C. in the atmosphere (viscosity was 1.5 times the initial value).
B: Branched polymethylhydrogensiloxane having a viscosity of 20 cSt represented by the unit formula M ^H ₈ Q ₄ C: A complex obtained by heating chloroplatinic acid with octyl alcohol and having a platinum content of 4% by weight.
D1; muscovite powder having an average particle size of 5 μm;
D2-1: Tetraethoxysilane D2-2: Methyltrimethoxysilane D2-3: Dimethyldiethoxysilane D3: Aluminum chelate compound represented by formula (V) Diluent-1: Both ends are blocked with M units, intermediate Silicone oil consisting of all D units and having a viscosity of 0.02 Pa · s at 23 ° C. Diluent-2: Both ends are blocked with M units, intermediate units are 70 mol% D units and 30 mol ^Dff units % Silicone oil having a viscosity of 0.02 Pa · s at 23 ° C. Adhesion imparting agent 1: organosilicon compound represented by formula (iv)

Examples 1-5, Comparative Examples 1-3
Each component shown in Part 1 of Table 1 was kneaded using a universal kneader under the conditions shown in Table 1 and cooled to room temperature (23 ° C.). Next, each component shown in Part 2 was added, and kneaded at room temperature (23 ° C.) using a universal kneader to prepare a polyorganosiloxane composition.

The following was measured about the composition of the Example and the comparative example.
(1) Viscosity / thixo ratio According to JIS K6249 rotational viscosity measurement method, the viscosity of the prepared composition was measured using a Brookfield viscometer at 23 ° C. with rotor no. 7 and the viscosity was 1 and 2 as measured at 4 rpm and 20 rpm. Viscosity 1 / viscosity 2 was calculated as the thixo ratio.
(2) Moisture permeability The prepared composition is poured into a stainless steel mold having a polytetrafluoroethylene treatment on the surface and cured by heating at 150 ° C. for 1 hour to obtain a thickness of 1.0 mm. A silicone rubber sheet was prepared. This was evaluated for moisture permeability at a temperature of 40 ° C. and a humidity of 90% RH in accordance with JIS Z0208.
(3) Mechanical properties The prepared composition was poured into a stainless steel mold having a polytetrafluoroethylene treatment on the surface, and heated at 150 ° C. for 1 hour to be cured, resulting in a thickness of 2.0 mm. A silicone rubber sheet was prepared. This was measured for tensile strength and elongation at break according to JIS K6249. In addition, three sheets obtained were overlapped to a thickness of 6 mm, and the hardness (type A durometer) was measured according to JIS K6249.

  The evaluation results are shown in Table 1.

  Examples 1-5 are excellent in the fluidity | liquidity before hardening, as shown by the viscosity 1, 2 and a thixo ratio. Moreover, it is excellent in moisture permeability after curing, and also has good mechanical properties as shown by type A hardness, tensile strength, and cut elongation. On the other hand, the comparative example 1 which mix | blended only the mica powder, the comparative examples 2 and 3 which lack either an organoalkoxysilane or an aluminum chelate compound have a high viscosity, compared with Examples 1-4 which have a common base polymer etc. It can be seen that the viscosity is high and the fluidity is poor.

Claims (8)

(A) 100 parts by weight of an alkenyl group-containing polyorganosiloxane containing two or more alkenyl groups bonded to silicon atoms in the molecule and having a viscosity at 23 ° C. of 0.1 to 1,000 Pa · s;
(B) A hydrogen bonded to a silicon atom with respect to one alkenyl group present in (A), a polyorganohydrogensiloxane bonded to a silicon atom and having an average of more than two hydrogen atoms in the molecule. An amount in which the number of atoms is 0.5 to 5.0;
(C) An amount of platinum group metal compound in which the platinum group metal atom is 0.1 to 1,000 ppm by weight with respect to the amount of (A); and (D) (D1) mica powder and (D2 Formula (IV):
R ¹⁰ _p Si (OR ¹¹ ) _4-p (IV)
(In the formula, R ¹⁰ is a C ₁ -C ₁₈ alkyl group, a C ₃ -C ₁₈ cycloalkyl group or an aryl group, R ¹¹ is a C ₁ -C ₆ alkyl group, and p is 0-3. A product obtained by mixing (D3) an aluminum chelate compound (wherein (D1) is 100% by weight and (D2) is 0.1 to 0.1%) 10% by weight, (D3) is 0.05 to 5% by weight) and (D1) is contained in an amount of 20 to 200 parts by weight. (A) is represented by formula (II):

(Where
R is independently R ³ or R ⁴ , at least two of R are R ³ ,
R ³ is independently a C ₂ -C ₆ alkenyl group,
R ⁴ is independently a C ₁ -C ₆ alkyl group or a phenyl group, and among R ⁴ , 15 mol% or more is a phenyl group,
2. The polyorganosiloxane composition according to claim 1, wherein m is a linear polyorganosiloxane represented by (A) having a viscosity at 23 ° C. of 0.1 to 1,000 Pa · s).   The polyorganosiloxane composition according to claim 1 or 2, wherein (D1) is mica powder having an average particle diameter of 1 to 100 µm.   The polyorganosiloxane composition according to any one of claims 1 to 3, wherein (D2) is one or more selected from the group consisting of methyltrimethoxysilane and tetraethoxysilane.   (D3) is aluminum ethyl acetoacetate diisopropylate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate, aluminum bisethyl acetoacetate monoacetylacetonate, aluminum alkyl acetoacetate diisopropylate and aluminum alkenyl acetoate The polyorganosiloxane composition according to any one of claims 1 to 4, wherein the polyorganosiloxane composition is one or more selected from the group consisting of acetate and diisopropylate.   6. (D1), (D2), and (D3) are mixed in presence of (A), Then, (B) and (C) are mix | blended and obtained by any one of Claims 1-5. Polyorganosiloxane composition.   A hard disk having a protective layer obtained by curing the polyorganosiloxane composition according to claim 1.   The display apparatus which has a protective layer obtained by hardening the polyorganosiloxane composition of any one of Claims 1-6.