JP3254962B2 - Heat-curable silicone elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-curable silicone elastomer composition which has good storage stability near room temperature, has excellent curability at high temperatures, and can be rapidly cured by a hydrosilylation reaction.

[0002]

2. Description of the Related Art
A heat-curable silicone elastomer composition that cures by a hydrosilylation reaction can be cured in an extremely short time and has advantages such as no reaction by-products.
It is used for coating agents, adhesives, liquid injection molding and the like.

However, since the heat-curable silicone elastomer composition has poor storage stability near room temperature, it must be divided into two components during storage and mixed at the time of use, which is troublesome in terms of workability. There was a problem that is.

In recent years, in order to solve this problem, compounds controlling a hydrosilylation reaction, such as nitrile compounds, carboxylate, metal compounds such as stannous and mercury, sulfur compounds,
It has been proposed to add benzotriazole, acetylene compounds, hydroperoxides, phosphorus compounds and the like. However, when long-term storage stability is to be obtained by adding these control agents to the above-mentioned silicone elastomer composition, there has been a drawback that the curability becomes extremely poor and the time required for curing becomes long.

[0005] Therefore, as a measure for remedying this drawback, a method has been proposed in which the hydrosilylation reaction catalyst is physically sealed with a substance which becomes solid at around room temperature and becomes liquid at high temperature. 53-4170
No. 7 proposes a method of adding a substance in which a platinum catalyst is sealed in a silicone resin having a softening point at a curing temperature. However, although this method can slightly improve the storage stability of the silicone elastomer composition, the platinum catalyst encapsulated in the silicone resin is not quickly released in a short time, and the encapsulated platinum catalyst can be used over time. There is a drawback that the curing properties are deteriorated due to the dissolution into the composition.

[0006] Japanese Patent Application Laid-Open No. 2-4833 proposes a method of microencapsulating a platinum catalyst with a silicone resin. However, this method uses a platinum catalyst in a system over time due to compatibility problems. And the pot life was not so long and costly.
JP-A-64-47442 proposes a method in which a platinum catalyst is microencapsulated with various organic polymers and washed with a solvent that dissolves the platinum catalyst but does not dissolve the organic polymer. Has the disadvantage that the steps are complicated and costly.

[0007] Accordingly, there has been a demand for the development of a technique for industrially advantageously improving the storage stability and curing properties of a heat-curable silicone elastomer composition.

SUMMARY OF THE INVENTION The present invention has been made to meet the above-mentioned demands, and has a good storage stability at around room temperature, has excellent curing characteristics at high temperatures, and can be rapidly cured by a hydrosilylation reaction. It is an object of the present invention to provide a type silicone elastomer composition.

[0009]

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that an organo-organic compound having at least two aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. Polysiloxane, an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and a compound capable of acting as a catalyst for a hydrosilylation reaction having an average particle size of 0.1 to 10;
A hydrosilylation reaction catalyst which is supported on a porous filler having a pore volume of 0 μm and a pore volume of 0.5 to ⁵ cm ³ / g and coated with a silicone resin having a melting point or softening point of 40 to 150 ° C. is blended. The present invention has been found to provide a heat-curable silicone elastomer composition having good storage stability at around room temperature, excellent curing properties at high temperatures, and being rapidly cured by a hydrosilylation reaction. Was reached.

Accordingly, the present invention provides: (1) an organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in one molecule; and (2) a hydrogen bonded to silicon atoms in one molecule. Organohydrogenpolysiloxane having at least two atoms: (1) to the silicon atom in the organohydrogenpolysiloxane of the component (2) to the aliphatic unsaturated hydrocarbon group bonded to the silicon atom in the organopolysiloxane of the component (3) an average particle diameter supporting a compound capable of serving as a catalyst for the hydrosilylation reaction is 0.1 to 100 μm, and a pore volume is 0.1 to 1: 1.
5 to ⁵ cm ³ / g of porous filler is further added to 40 to 150 cm ³ / g.
A hydrosilylation reaction catalyst coated with a silicone resin having a melting point or softening point of 0 ° C .: A heat-curable silicone elastomer composition characterized by blending a catalytic amount.

Now, the present invention will be described in further detail. The first essential component of the heat-curable silicone elastomer composition of the present invention comprises at least two aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. This is an organopolysiloxane having a number of components, which is a main component of the composition of the present invention.

Here, as the organopolysiloxane, those represented by the following composition formula (1) can be used. R ¹ _a R ² _b SiO _{[4- (a + b)] / 2} (1) (where R ¹ is a monovalent aliphatic unsaturated hydrocarbon group, R ²
Is a substituted or unsubstituted monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon group, and a and b are each 0 <a ≦ 1, 1 ≦
b <3, 1 <a + b ≦ 3, preferably 0.0005 ≦ a
≦ 0.1, 1.8 <b ≦ 2.2, 1.9 ≦ a + b ≦ 2.
It is a number that satisfies 25. )

In the above formula (1), R ¹ is a vinyl group,
Allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, hexenyl group, etc.
It is an aliphatic unsaturated hydrocarbon group such as 0, especially 2 to 4 alkenyl groups, and a vinyl group is particularly preferred. R ² preferably has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
tert-butyl group, hexyl group, cyclohexyl group,
Alkyl groups such as octyl group and decyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and phenylethyl group, and hydrogen atoms such as chlorine, bromine and fluorine Examples thereof include a chloromethyl group, a bromoethyl group, a trifluoropropyl group, and a cyanoethyl group substituted with a halogen atom and a cyano group, and a methyl group, a phenyl group, and a trifluoropropyl group are particularly preferable. In the above formula (1), each substituent may be different or the same, but it is necessary that one molecule contains two or more aliphatic unsaturated hydrocarbon groups such as alkenyl groups. is there. In addition, this organopolysiloxane is generally a linear diorganopolysiloxane in which a main chain portion basically consists of repeating diorganosiloxane units, and both ends of a molecular chain are blocked with a triorganosiloxy group. _May be branched or cyclic containing R ¹ SiO _3/2 units, R ² SiO _3/2 units or SiO _4/2 units. The aliphatic unsaturated hydrocarbon group contained in the molecule may be bonded to any silicon atom at the terminal of the molecular chain or in the middle of the molecular chain. It is desirable that the compound has a modified aliphatic unsaturated group from the viewpoint of the curing speed and the physical properties of the cured product. Incidentally, the average degree of polymerization of the organopolysiloxane (that is, the number of silicon atoms in the molecule) is 20 or more,
Usually, about 20 to 5,000 is suitable, and the viscosity at 25 ° C. is usually 10 to 1,000,000 cs, particularly 1
Those having about 100 to 100,000 cs are preferably used.

Next, an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule of the second component is a component serving as a crosslinking agent for the organopolysiloxane of the first component. Composition formula (2)
Are preferably used. R ³ _{c Hd} SiO _{[4- (c + d)] / 2} (2) (wherein R ³ is a substituted or unsubstituted monovalent hydrocarbon group,
c and d are respectively 1 ≦ c ≦ 2.2 and 0.002 ≦ d ≦ 1
1 ≦ c + d ≦ 3, preferably 1 <c ≦ 2, 0.01 ≦
This is a number that satisfies 1.8 ≦ c + d ≦ 2.5 when d <1. )

In the above formula (2), R ³ is preferably the same as R ² which has no aliphatic unsaturated bond having preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. The same monovalent hydrocarbon group, for example, a methyl group,
Alkyl groups such as ethyl group, propyl group and butyl group, aryl groups such as phenyl group and tolyl group, chloromethyl group in which some or all of these groups have been replaced with halogen atoms or cyano groups, trifluoropropyl And a cyanoethyl group. The organohydrogenpolysiloxane is generally linear, but may have a partially branched or cyclic skeleton.

The average degree of polymerization of the organohydrogenpolysiloxane (that is, the number of silicon atoms in the molecule)
Is preferably 3 to 300. This organohydrogenpolysiloxane has at least two, preferably at least three, hydrogen atoms (i.e., SiH groups) bonded to silicon atoms in one molecule (for example, usually about 3 to 100). This hydrogen atom may be bonded to either the silicon atom at the terminal of the molecular chain or the silicon atom in the middle of the molecular chain, or may be bonded to both.

The compounding amount of the above-mentioned organohydrogenpolysiloxane is such that a hydrogen atom bonded to a silicon atom in one molecule and an aliphatic unsaturated hydrocarbon bonded to a silicon atom in one molecule of the first component organopolysiloxane. The molar ratio with the group is preferably in the range of 10: 1 to 1:10, particularly preferably 3: 1 to 1: 3.

The hydrosilylation reaction catalyst used as the third essential component in the present invention is obtained by supporting a compound capable of acting as a hydrosilylation reaction catalyst on a porous filler.
This is a catalyst for crosslinking an unsaturated unsaturated hydrocarbon group bonded to a silicon atom in the first component and a hydrogen atom bonded to a silicon atom in the second component (that is, a SiH group) by a hydrosilylation reaction. It is an active ingredient.

In this case, as a compound that can be a catalyst for the hydrosilylation reaction, a known platinum group metal compound such as a platinum-based, rhodium-based, or palladium-based compound can be used. Of these, platinum-based catalysts are preferred. These compounds can be used as they are, but they may be used after being diluted with a solvent such as alcohols, aromatic compounds, hydrocarbons, ketones, and chlorine compounds.

The porous filler to be supported has an average particle size of 0.1 to 100 μm, particularly 1 to 50 μm.
If the average particle size is less than 0.1 μm, it may be difficult to carry the catalyst or the function as a catalyst may be impaired. If it exceeds 100 μm, the cured silicone elastomer composition May adversely affect the physical properties of the material.

Further, the pore volume of the porous filler is 0.1.
5-5cm^Three / G, especially 1-4 cm^Three / G is preferred,
0.5cm^Three / G Compound supported as catalyst
Difficult to carry out, insufficient support, silicone elastomer
-Where it is difficult to extend the pot life of the composition
5cm^Three / G exceeds the strength of the filler itself
Problems with the silicone elastomer after curing
It may adversely affect the physical properties of the product.

Specific examples of such a porous filler include diatomaceous earth, silica, and metal oxides (eg, alumina, titanium oxide, etc.).

As a method of supporting the compound capable of undergoing the hydrosilylation reaction on the porous filler, any method may be employed. For example, the filler is suspended in a solvent, and the suspension serves as a catalyst. Add compound and add 50-1
A method of aging at 00 ° C. can be conveniently and suitably employed. In addition, depending on the type of compound that can be a catalyst for the hydrosilylation reaction to be supported, a silylating agent such as methylchlorosilane such as methyltrichlorosilane, dimethyldichlorosilane and trimethylchlorosilane, organochlorosilanes such as methylchlorosilane, and hexamethyldisilazane may be used. May be hydrophobized by an organosilazane such as organodisilazane, or an organodisiloxane or cyclosiloxane such as hexamethyldisiloxane or octamethylcyclotetrasiloxane. this is,
Usually, a highly polar hydrosilyl group is present on the filler surface, and if a compound having a hydrophobic ligand is carried as it is, it repels each other due to a difference in polarity and cannot be carried successfully. Is preferably made hydrophobic so that the polarity can be made closer so that loading can be carried out smoothly.

Further, according to the present invention, the pot life of the composition can be sufficiently extended only by supporting the compound which can be a catalyst for the hydrosilylation reaction on the porous filler. Coating with Thereby, the pot life of the composition can be further extended.

The silicone resin preferably has a melting point or softening point in the range of 40 to 150 ° C., particularly 60 to 130 ° C. That is, the melting point or softening point is 40
If the temperature is lower than 0 ° C, the catalyst component tends to ooze out of the silicone resin during storage of the composition, which may cause a problem in storage stability. On the other hand, when the temperature is higher than 150 ° C., the silicone resin does not melt or soften effectively and quickly at the time of heat curing, and the catalyst component does not exude, so that it may be difficult to perform the curing effectively.

Further, from the viewpoint that this silicone resin can be effectively dispersed in the composition without dissolving in other components in the composition, the following average composition formula R ⁴ _e SiO _{(4-e) / 2} (formula Wherein R ⁴ may be the same or different and is an unsubstituted or substituted monovalent hydrocarbon group having usually 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, having no aliphatic hydrocarbon group. , E is a number from 0.8 to 1.8, preferably from 1 to 1.5.) Is suitably used. Where:
Examples of the monovalent hydrocarbon group R ⁴ include groups other than the alkenyl group among the groups exemplified for the above R ² , and it is particularly preferable that 50 mol% or more thereof is a phenyl group or a fluorine-containing group. The molecular structure is linear,
It may have a branched or network structure, and the degree of polymerization is preferably 20 or more. In particular, at least R ⁴ ₃ SiO least R ⁴ monoorganosiloxane units represented by SiO _3/2, or in a molecule in a molecule
It is preferable to have a branched or three-dimensional network structure containing a triorganosiloxy unit represented by _1/2 and a SiO ₂ unit.

The amount of the hydrosilylation reaction catalyst added is
The catalyst amount can be a usual catalyst amount, and particularly when a white metal compound is used, 0.1% in a normal composition in terms of white metal metal.
It is used in a proportion such that it is contained in an amount of ５００500 ppm, preferably 1-100 ppm.

The silicone elastomer composition of the present invention may contain optional components other than the above-mentioned essential components, if necessary. For example, nitrogen-containing compounds such as tetramethylenediamine and benzotriazole, acetylene compounds such as ethynylcyclohexanol and propargyl alcohol, phosphorus compounds such as hydroperoxide and triphenylphosphine, nitrile compounds, carboxylate, stannous and mercuric mercury Hydrosilation reaction control agents such as metal compounds such as sulfur compounds, fillers such as silica fine particles and calcium carbonate, heat-resistant agents such as iron oxide and cerium oxide,
Examples include flame retardants such as carbon black, adhesion-imparting agents, and thixotropy-imparting agents. In addition, the addition amount of these optional components can be a usual amount as long as the effect of the present invention is not hindered.

[0029]

The heat-curable silicone elastomer composition of the present invention has good storage stability near room temperature,
It has excellent curing properties at high temperatures and can be rapidly cured by a hydrosilylation reaction, and can be widely used as a potting agent, a coating agent, an adhesive, a liquid injection molding, and the like.

[0030]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples.

[Synthesis Example 1] Stirrer, thermometer, reflux condenser
400 g of toluene in a flask equipped with
0.3 μm, pore volume 2.3 cm^Three / G radio
Light micro fine (diatomaceous earth, manufactured by Showa Chemical Industry Co., Ltd.)
150 g was charged and suspended at room temperature with stirring. So
In the butanol solution of chloroplatinic acid (to 1% platinum concentration)
Adjusted) After dropping 7.5 g, 1 hour at 70 ° C
Stirred. Further, the solvent was blown off under reduced pressure at 70 ° C.
After drying under reduced pressure for 8 hours at ℃, diatomaceous earth carrying platinum
(Platinum concentration adjusted to 0.1%, catalyst 1) was obtained.

[Synthesis Example 2] 150 g of the same Radiolite Microfine (manufactured by Showa Chemical Industry Co., Ltd.) as used in Synthesis Example 1 was silylated with hexamethyldisilazane and subjected to a hydrophobic treatment. As a platinum compound to be dropped, a toluene solution of a platinum complex having divinyltetramethyldisiloxane as a ligand (at a platinum concentration of 0.1%).
Example 1 except that 15 g was used.
In the same manner as in the above, catalyst 2 was obtained.

[Synthesis Example 3] A silicone resin (C ₆ ) having a softening point of 83 ° C. was applied to the catalyst 1 obtained in Synthesis Example 1 by using a spiral flow (coating device manufactured by Freund Corporation).
H ₅ SiO _{3/2 units: 70mol%, C 3 H 7} SiO 3/2 units: coated with 30 mol%), to obtain catalyst 3.

Synthesis Example 4 30 g of a toluene solution of a platinum complex having divinyltetramethyldisiloxane as a ligand (a platinum concentration adjusted to 0.5%) and the same phenyl group as used in Synthesis Example 3 30 g of a silicone resin containing 70 mol% was dissolved in 150 g of dichloromethane, and 20 g of fine particles of a silicone resin containing a platinum catalyst were obtained by a spray drying method (adjusted to a platinum concentration of 0.5%, catalyst 4).

[Synthesis Example 5] Supported as in Synthesis Example 1,
Average particle size 3.56 μm, pore volume as filler
Is 0.26cm^Three / G AMT-silica 300BTE
(150 g of Mizusawa Chemical Industry Co., Ltd.)
1% of catalyst was obtained (catalyst 5).

REFERENCE EXAMPLE 1 Hexamethyldisilazane having a specific surface area of 150 m ² / g was added to 900 g of α, ω-divinyldimethylpolysiloxane in which both ends of a molecular chain having a viscosity of 10,000 cs at 25 ° C. were blocked with vinyldimethylsilyl groups. The base compound was obtained by mixing 300 g of fumed silica whose surface had been hydrophobized with.

Next, Me ₃ SiO— (Me ₂ SiO) ₁₈ — (MeHSiO) _{20 was} added to 120 g of the base compound.
Methylhydrogenpolysiloxane (wherein Me represents a methyl group.) Represented by -SiMe ₃ 50% toluene solution of 1.24g and ethynyl cyclohexanol 0.
02 g was added and mixed until uniform, to obtain a silicone base 1.

121.26 g of the above silicone base 1
Then, 0.6 g of the catalyst 1 obtained in Synthesis Example 1 was added thereto, and the mixture was uniformly stirred and mixed to obtain a silicone composition.

Reference Example 2 To 121.26 g of the above-mentioned silicone base 1, 0.6 g of the catalyst 2 obtained in the above-mentioned Synthesis Example 2 was added and uniformly stirred and mixed to obtain a silicone composition.

Example 1 To 121.26 g of the above-mentioned silicone base 1, 0.6 g of the catalyst 3 obtained in the above-mentioned Synthesis Example 3 was added and uniformly stirred and mixed to obtain a silicone composition.

[Comparative Example 1] 1 of the above silicone base 1
0.06 g of a butanol solution of chloroplatinic acid (adjusted to a platinum concentration of 1%) was added to 21.26 g, followed by uniform stirring and mixing to obtain a silicone composition.

[Comparative Example 2] 121.
To 26 g, 0.12 g of the catalyst 4 obtained in the above Synthesis Example 4 was added and uniformly stirred and mixed to obtain a silicone composition.

[Comparative Example 3] 121.
To 26 g, 0.6 g of the catalyst 5 obtained in Synthesis Example 5 was added, and the mixture was stirred and mixed uniformly to obtain a silicone composition.

The curing properties and pot life of the obtained silicone composition were measured by the following methods. Table 1 shows the results. Curing characteristics : Use a rheometer manufactured by Toyo Seiki Co., Ltd.
Measured under the conditions of 0 ° C. and a swing angle of 3 °.
% Time is T10 (second), 90% time is T9
0 (second). 25 ℃, 40 pot life
The number of days until gelation at ℃ (closed system) was measured.

From the results shown in Table 1, it was confirmed that the heat-curable silicone elastomer composition of the present invention had excellent storage stability at around room temperature and excellent curing properties at high temperatures.

[0046]

[Table 1]

Continued on the front page (72) Inventor Kazutoshi Fujioka 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Laboratory (56) References JP-A-5-5062 (JP, A) JP-A-59-108062 (JP, A)

Claims (3)

(57) [Claims] (1) an organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in one molecule; and (2) at least two hydrogen atoms bonded to silicon atoms in one molecule. Organohydrogenpolysiloxanes having one or more hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane of component (2) relative to aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in the organopolysiloxane of component (1) (3) an average particle diameter of 0.1 to 100 μm supporting a compound capable of serving as a catalyst for the hydrosilylation reaction, and a pore volume of 0.1 to 100 μm.
5 to ⁵ cm ³ / g of porous filler is further added to 40 to 150 cm ³ / g.
A hydrosilylation reaction catalyst coated with a silicone resin having a melting point or a softening point of ° C .: a heat-curable silicone elastomer composition comprising a catalytic amount. 2. The composition according to claim 1, wherein the filler is hydrophobized. 3. The silicone resin has the following average composition formula: R ⁴ _e SiO _{(4-e) / 2} (where R ⁴ may be the same or different and does not have an aliphatic hydrocarbon group) Is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, of which 50 mol% or more is a phenyl group or a fluorine-containing group, and e is 0.8 to
1.8. 3. The composition according to claim 1, which is represented by the following formula: