JP3109404B2 - Method for producing silicone rubber compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicone rubber compound having improved crepe hardening and excellent storage stability.

[0002]

BACKGROUND OF THE INVENTION When a large amount of a silica filler is added to a silicone polymer, the composition is made to have excellent physical properties such as tensile strength, tear strength, elongation and heat resistance. Is known to be.
However, in order to incorporate a large amount of silica filler into the silicone polymer, it is necessary to add a large amount of a wetter (dispersant) in order to improve the dispersibility of the silica filler.

Conventionally, as a wetter, the following formula HO [(CH_Three)_TwoSiO]_xH, (x = 10 to 20) α, ω-siloxane
Oars have been commonly used (US Pat. No. 3,795).
9,962). Also, RO [(CH_Three)_TwoSiO]
_yH (R : Α-alkoxy having a short-chain alkyl group, y = 3 to 5)
Xy-ω-siloxanol is also known, and
Samethyltrisiloxanediol and methoxyhexamethyl
Anti-Structure Using a Mixture of Rutriciloxanol
Char agents have also been proposed (US Pat. No. 3,925,2).
No. 85).

However, in the conventional wetter, if the crepe hardening is reduced to a relatively large amount, the silicone rubber composition becomes sticky, the workability is deteriorated, and the mechanical properties of the cured product are reduced. Therefore, if the addition amount is reduced, the stickiness disappears, but there are problems such as remarkable crepe hardening,
When the silica is mixed and dispersed, the wettability of the silica is poor, and the resulting compound is dry,
There was a problem of falling apart. Therefore, development of a wetter which has little crepe hardening, has no stickiness, and improves the mechanical properties of a cured product has been desired.

In order to solve such problems, the present inventor has previously disclosed Japanese Patent Application Nos. 5-302409 and 6-431.
No. 95 and Japanese Patent Application No. 6-75318 have proposed a novel silicone rubber composition by compounding a wetter. However, when a normal-pressure hermetic dumixer or the like usually used for compounding a silicone rubber compound is used, Although the results of improving the above-mentioned problems to a certain extent were obtained, the process time required for obtaining the expected physical properties was long, and the vulcanization physical properties of the obtained rubber were still unsatisfactory. In addition, when using a closed-type pressure mixer such as a Banbury mixer or a pressure kneader, the compounding time can be shortened, but the process time for obtaining the expected physical properties is long, They still complained about the vulcanization properties.

The present invention has been made in order to improve the above circumstances, and has a silicone rubber composition which provides a silicone rubber having improved crepe hardening, excellent storage stability, small compression set and excellent mechanical strength. An object of the present invention is to provide a method for producing a silicone rubber compound for obtaining a product in a short time.

[0007]

The present inventors have made intensive studies to achieve the above object and found that (A) the following general composition formula (1): R ¹ _a SiO _{(4-a) / 2} (1) (In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and 0.001 to 0.5 mol% of R ¹ is an alkenyl group. A is 1.95 to An organopolysiloxane having an average degree of polymerization of at least 100, (B) a reinforcing silica filler having a specific surface area of at least 50 m ² / g by the BET method, and (C) a silicon atom. Is a pressure-type mixer or a continuous mixer comprising a component comprising one or more catalysts selected from among the following: a hydroxyl group-containing silicon compound of 5 or less, (D) phosphorus siliconate, a tertiary amine and a quaternary ammonium compound. To produce silicone rubber compound It has been found that crepe hardening is improved in a shorter process compared to the conventional method, and that a silicone rubber having a small increase in plasticity even after long-term storage and excellent vulcanization properties can be obtained. It is something that has been done.

[0008] Hereinafter, the more detailed description of the present invention, the present invention is, (A) the following general formula ^{_{(1) R 1 a SiO (}} 4-a) / 2 ... (1) ( In the formula, R ¹ is a substituted Or an unsubstituted monovalent hydrocarbon group, wherein 0.001 to 0.5 mol% of R ¹ is an alkenyl group, and a is a positive number of 1.95 to 2.05.) Organopolysiloxane having an average degree of polymerization of 100 or more, (B) a reinforcing silica filler having a specific surface area of 50 m ² / g or more by a BET method, (C) a hydroxyl-containing silicon compound having 5 or less silicon atoms, (D ) A silicone rubber compound is produced by dispersing and mixing a component comprising one or more catalysts selected from phosphorus siliconates, tertiary amines and quaternary ammonium compounds with a pressure mixer or a continuous mixer. It is.

The organopolysiloxane as the component (A) used in the production of the silicone rubber compound is represented by the following general composition formula (1): R ¹ _a SiO _{(4-a) / 2} (1) , R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, wherein 0.001 to 0.5 mol% of R ¹ is an alkenyl group, and a is a positive number of 1.95 to 2.05. Is an organopolysiloxane having an average degree of polymerization of 100 or more.

Here, in the formula (1), R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and preferably has 1 to 10, more preferably 1 to 6, carbon atoms. in this case,
0.001 to 0.5 mol% of alkenyl groups in all R ¹ groups
, And more preferably 0.01 to 0.3 mol%. If the proportion of this alkenyl group is too small, the curability of the resulting composition will be reduced, and if it is too large, the resulting cured product will have reduced physical properties such as tensile strength, tear strength and elongation. I do.
In addition, as such an alkenyl group, for example, a vinyl group,
Examples thereof include an allyl group and a butenyl group, and a vinyl group is preferable.

The R ¹ group other than the alkenyl group includes, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl,
Alkyl groups such as dodecyl groups, phenyl groups, aryl groups such as tolyl groups, unsubstituted hydrocarbon groups such as aralkyl groups such as β-phenylethyl group, and some or all of the hydrogen atoms in these hydrocarbon groups Examples thereof include a substituted hydrocarbon group such as a halogen atom, a 3,3,3-trifluoropropyl group, and a cyanoethyl group substituted with a cyano group. Of these, a methyl group is generally preferred,
When imparting radiation resistance and transparency, it is preferred that the phenyl group be contained in a proportion of 2 to 20 mol% of all R ¹ groups. In addition, when imparting oil resistance and gasoline resistance, it is preferable that a cyanoethyl group, a 3,3,3-trifluoropropyl group and the like are contained in a proportion of 5 to 70 mol% in all R ¹ groups.

A must be a number in the range of 1.95 to 2.05, and more preferably 1.98 to 2.02
It is. When a is outside the above range, the polymerization degree is 10
Difficulties arise when synthesizing zero or more organopolysiloxanes.

In the organopolysiloxane of the component (A) used in the present invention, most of the constituent units are diorganosiloxane units, but triorganosiloxane units and SiO ₂ units are contained in 1 mole of the organopolysiloxane. %. Further, the terminal of the molecular chain may be blocked with a hydroxyl group or a triorganosilyl group. Preferred examples of the molecular chain terminal include a dimethylvinylsilyl group, a trimethylsilyl group, a trivinylsilyl group, and a dimethylhydroxysilyl group. Further, the degree of polymerization of the organopolysiloxane is required to be 100 or more in order for the cured product of the obtained composition to obtain sufficient mechanical strength, and preferably 100 to 100.
00, more preferably 2,000 to 10,000.

Specific surface area as component (B) (BET method)
Examples of the reinforcing silica filler having a particle size of 50 m ² / g or more include fumed silica and precipitated silica. These may be used alone or in combination of two or more. In particular, in terms of transparency and reinforcing property of the obtained silicone rubber composition, the specific surface area is 100 to 400 m ² /
g of fumed silica is preferred. In terms of physical properties such as cost and elasticity of the obtained silicone rubber composition, precipitated silica having a specific surface area of 50 to 800 m ² / g is particularly desirable.

These silica fillers may be those whose surfaces are treated with, for example, a chain organopolysiloxane, a cyclic organopolysiloxane, hexamethyldisilazane or the like.

In this case, the water content in the reinforcing silica is desirably 2% by weight or less. If the amount of water is large, the steps required to obtain preferable physical properties may be long.

The amount of the silica filler is 5 to 10 parts by weight per 100 parts by weight of the organopolysiloxane (A).
The proportion of 0 parts by weight is preferred, and more preferably 10 to 50 parts by weight.
Parts by weight. If the compounding amount is too large or too small, the processability of the obtained silicone rubber composition is reduced, and the cured product obtained by curing the silicone rubber composition has sufficient tensile strength, tear strength and the like. In some cases, it has no mechanical strength.

The hydroxyl group-containing silicon compound having 5 or less silicon atoms as the component (C) improves the dispersibility of the organopolysiloxane and the reinforcing silica filler, and provides a silicone rubber compound having improved crepe hardening. And to improve the physical properties of the silicone rubber when crosslinked. Examples of the hydroxyl group-containing silicon compound having 5 or less silicon atoms include the following.

[0019]

Embedded image

Here, R ² is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and R ² may be the same or different. In this case, as the monovalent hydrocarbon group for R ² , those similar to R ¹ can be exemplified. In particular, a methyl group, a vinyl group,
A 3,3,3-trifluoropropyl group is preferred from the viewpoint of more effectively exhibiting the effects of the present invention, and a methyl group is most preferred. R ³ represents a methyl group, a trimethylsiloxy group, a vinyl group, or a trifluoropropyl group, and b represents 0, 1, 2, or 3 (provided that the number of silicon atoms is 5 or less).

The amount of the hydroxyl group-containing silicon compound having 5 or less silicon atoms as the component (C) is preferably 1 to 30% by weight, more preferably 1 to 30% by weight, based on the reinforcing silica filler. Is 1 to 20% by weight, and if the amount is less than 1% by weight, the activity of silica is strong,
If the crepe hardening is not improved, and if it is more than 30% by weight, the composition may become sticky or fall off, which may increase the cost.

The component (D) is a catalyst selected from phosphorus siliconates, tertiary amines and quaternary ammonium compounds. These catalysts may be used alone or in combination of two or more. Can be. Here, the phosphorus siliconate catalyst is obtained by reacting an organophosphorus compound with an organosiloxane. It can be obtained by reacting with cyclotrisiloxane. For example, n-tetrabutylphosphonium hydroxide and hexamethylcyclotrisiloxane are charged at a weight ratio of 1:10, reacted at a temperature of 40 to 45 ° C. and a pressure of 30 mmHg for 10 to 20 hours, sufficiently dehydrated and transparent. 20m after
It can be obtained by continuing the reaction at a pressure of mHg for about 2 hours. On the other hand, as the tertiary amine, tetramethyl-guanidyl-propyl-trimethoxysilane, diethyl-trimethyl-aminosilazane, and as the quaternary ammonium compound, tetramethylammonium hydroxide or the like is preferably used. Can be. The catalyst of component (D) is an essential component for accelerating the reaction between silica and a wetter, and is an important component of the present invention.

The amount of component (D) is 0.01 to 100 parts by weight of organopolysiloxane as component (A).
It is desirable that the content be 1 to 1 part by weight. If the amount is too small, the effect is not exhibited. If the amount is too large, the heat resistance and compression set of the silicone rubber may be significantly reduced.

When the silicone rubber compound of the present invention is obtained, the above-mentioned organopolysiloxane, silica filler, a hydroxyl-containing silicon compound having 5 or less silicon atoms,
In addition, a component comprising one or more kinds of catalysts selected from a phosphorus siliconate, a tertiary amine and a quaternary ammonium compound is mixed and dispersed and mixed by a pressurized mixer or a continuous mixer. In other non-pressurized mixers, open mixers, and the like, the mixing and dispersing properties are poor, the physical properties are reduced, and the process time is long, and the object of the present invention cannot be achieved.

In this case, examples of the pressure-type mixer include a Banbury mixer, a pressure kneader, an intermix and the like, and examples of the continuous mixer include a twin-screw mixer and a single-screw mixer. Two (manufactured by Toshiba Machine Co.) TEM as axial mixer, WP (WelneR ¹ & Pfleidler Co., Ltd.), as a uniaxial mixer Ko-Kneeder (B
uss).

The compounding and dispersing step is started at 100 ° C. or less, more preferably at 0 to 70 ° C.
It is preferable that the hydroxyl group-containing silicon compound having 5 or less silicon atoms as a wetter is selected from phosphorus siliconates, tertiary amines, and quaternary ammonium compounds. The reaction with the silica filler can be effectively and rapidly performed by two or more kinds of catalysts.

The water content of the reinforcing silica filler is desirably 2% by weight or less as described above, and if it is more than 2% by weight, it takes time to raise the temperature of the composition,
In some cases, the reduction of the process time, which is the object of the present invention, is not achieved.

The silicone rubber compound includes:
If necessary, various compounding agents usually compounded in silicone rubber may be added. For example, crushed silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, carbon black, barium oxide, magnesium oxide, cerium hydroxide, calcium carbonate, magnesium carbonate, zinc carbonate, asbestos,
Glass wool, fine powder mica, fused silica powder and the like may be blended. If necessary, a pigment, a dye, an antioxidant, an antioxidant, an antistatic agent, a flame retardant (eg, antimony oxide, paraffin chloride, etc.), and a thermal conductivity improver (eg, boron nitride, aluminum oxide, etc.) are compounded. May be. These components can be dispersed and mixed together with the components (A) to (D).

A curable silicone rubber composition can be obtained by adding a curing agent to the silicone rubber compound thus obtained. In this case, as the curing agent, when the composition is cured by a hydrosilylation reaction, an organohydrogenpolysiloxane and a platinum group metal-based catalyst are used, and when peroxide crosslinking is performed, a peroxide is used. Known ones are used.

More specifically, in the case of curing by a hydrosilylation reaction, an organohydrogenpolysiloxane and a platinum group metal-based catalyst are used as curing agents,
It can be cured by heating at a temperature of 200 ° C. for 0.5 minutes to 5 hours. As the organohydrogenpolysiloxane to be used, the following average composition formula (2) R ⁴ _{c Hd} SiO _{(4-cd) / 2} (2) (wherein R ⁴ is a substituted or unsubstituted carbon atom having 1 carbon atom) Represents a monovalent hydrocarbon group of 10 to 10, 0 ≦ c <3 and 0 <d ≦ 3, and c + d is a number satisfying 1.0 to 3.0.)
And those having two or more -SiH groups in the molecular chain. The -SiH group may be at the terminal of the molecular chain or may be in the middle. In the above average composition formula (2), as R ⁴ , those similar to R ¹ can be mentioned. For example, alkyl groups such as methyl group, ethyl group, propyl group and butyl group, phenyl group, tolyl group and the like can be mentioned. Examples include an unsubstituted hydrocarbon group such as an aryl group, and a substituted hydrocarbon group such as a 3,3,3-trifluoropropyl group.

The organohydrogenpolysiloxane used as the curing agent preferably has a degree of polymerization of 200 or less, and may be in a linear, cyclic or branched state. Examples of such an organohydrogenpolysiloxane include the following.

[0032]

Embedded image (In the formula, Me is a methyl group, i and j are integers of 0 or more, and k is an integer of 2 or more.)

The amount of the above-mentioned organohydrogenpolysiloxane is such that the amount of the ≡SiH group in the organohydrogenpolysiloxane is 0.5 to 3 mol per 1 mol of the alkenyl group in the organopolysiloxane (A). Is more preferable, and is more preferably an amount of 1 to 2 mol.

Examples of the platinum group metal-based catalyst include platinum-based, palladium-based and rhodium-based catalysts, and among them, platinum-based catalysts are preferred. As such a platinum-based catalyst, for example, a fine powdered metal platinum catalyst (for example, US Pat.
70150), chloroplatinic acid catalysts (e.g., those described in U.S. Pat. No. 2,823,218), platinum-hydrocarbon complex compounds (e.g., those described in U.S. Pat. No. 3,159,601 or U.S. Pat. No. 3,159,662), Chloroplatinic acid-olefin complex compounds (for example, U.S. Pat.
946), platinum-vinylsiloxane complexes (e.g. U.S. Pat. No. 3,775,452 or U.S. Pat.
No. 814780). The amount used is usually 0.1 to 1000 ppm (in terms of platinum) with respect to the total amount of the organopolysiloxane (A) and the above-mentioned organohydrogenpolysiloxane.
More preferably, it is 1 to 100 ppm (in terms of platinum).

In the case of curing by such a hydrosilylation reaction, in order to maintain the storage stability of the obtained silicone rubber composition at room temperature and an appropriate pot life, for example, a reaction with methylvinylcyclotetrasiloxane, acetylene alcohol, etc. Control agents may be added.

On the other hand, in the case of curing with an organic peroxide, usually 0.01 to 3 parts by weight of an organic peroxide is blended per 100 parts by weight of the organopolysiloxane. More preferably, it is 0.05 to 1 part by weight. The resulting silicone rubber composition is usually 10 to 500 ° C. at 10 ° C.
It can be cured by heating for seconds to 5 hours.

The organic peroxide as a curing agent may be any one usually used in peroxide-curable silicone rubber compositions, such as benzoyl peroxide, monochlorobenzoyl peroxide, ditertiary butyl peroxide, and the like. 2,5-dimethyl-di-tert-butyl peroxide, p-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, tert-butyl perbenzoate, tert-butyl peroxyisopropyl carbonate, dimyristyl per Oxycarbonate, dicyclododecyl peroxydicarbonate, 2,
5-bis- (tert-butylperoxy) -2,5
-Dimethylhexane, 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexine, etc., and these may be used alone or in combination of two or more.

[0038]

According to the present invention, a silicone rubber compound having improved crepe hardening, excellent storability, and good workability can be reliably produced. By using this compound, the compression set is small, A transparent silicone rubber with good mechanical properties is obtained, which makes it suitable as a material for extrusion molding, for example for building gaskets, medical tubing, etc., and also for rubber contacts, nipples, joint boots, plug boots, anodes It is also suitable as a material for caps and electric wires.

[0039]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the examples, parts represent parts by weight.

[Examples 1 to 3, Comparative Examples 1 and 2] (C
99.825 mol% of H ₃ ) ₂ SiO units, (CH ₃ )
0.15 mol% of (CH ₂ ＣＨCH) SiO units, (CH ₂ CH)
= CH) (CH ₃ ) ₂ SiO _1/2 unit is 0.025 mol%
Fumed silica having a specific surface area of 200 m ² / g in 100 parts of methylvinylpolysiloxane having an average degree of polymerization of 4000 (adsorbed water content: 0.3% by weight) (produced by Nippon Aerosil Co., Ltd., trade name: Erosil 200) 40 parts, 1,1,
3 parts of 3,3-tetramethyldisiloxane-1,3-diol and phosphorus siliconate were mixed in the composition shown in Table 1 using a pressure kneader to produce a silicone rubber compound. In addition, the compounding temperature at this time is started from 40 ° C.,
It reached 150 ° C. The time required was about 20 minutes.

For comparison, silicone rubber compounds were obtained in the same manner when no phosphorus siliconate was added (Comparative Example 1) and when a non-pressurized kneader mixer was used (Comparative Example 2).

Next, 0.5 part of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 100 parts of the obtained silicone rubber compound, and press cure was performed at 170 ° C. / 10 minutes, cured at 200 ° C. for 4 hours, to obtain a silicone rubber. The physical properties are shown in Table 1.

[0043]

[Table 1]

As is evident from the results in Table 1, the system without the addition of phosphorus siliconate was a compound having large plastic reversion and inferior workability, and also had a large compression set in terms of physical properties and was inferior in characteristics. When the composition was compounded using a non-pressurized kneader mixer instead of the pressure kneader, the composition was not integrated and the compounding was difficult. On the other hand, by adopting the method of the present invention, a silicone rubber having easy rubber compounding and good rubber properties could be obtained.

[Examples 4 to 6, Comparative Examples 3 and 4] (C
99.825 mol% of H ₃ ) ₂ SiO units, (CH ₃ )
0.15 mol% of (CH ₂ ＣＨCH) SiO units, (CH ₂ CH)
= CH) (CH ₃ ) ₂ SiO _1/2 unit is 0.025 mol%
Of methylvinylpolysiloxane having an average degree of polymerization of 4000 and 100 parts of precipitated silica having a specific surface area of 195 m ² / g (Nipsil Lp, trade name, manufactured by Nippon Silica Co., Ltd.). 45 parts, 1,1,3,3-tetramethyldisiloxane-1,3-diol 2 parts and phosphorus siliconate were mixed using a pressure kneader with the composition shown in Table 2. And
A silicone rubber compound was manufactured. The compounding temperature at this time was started from 45 ° C. and reached 160 ° C. The time required was about 25 minutes.

The obtained silicone rubber compound 10
0.5 parts of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 parts, and press cure was performed at 170 ° C. for 10 minutes and post cure at 200 ° C. for 4 hours. Cured under the conditions to obtain a silicone rubber. The physical properties are shown in Table 2.

[0047]

[Table 2]

As is evident from the results in Table 2, the system without the addition of phosphorus siliconate was a compound having large plastic reversion and poor workability, and also had a large compression set and physical properties and was inferior in characteristics. In addition, when compounding was performed using a non-pressurized type kneader mixer instead of the pressurized kneader, the composition was not integrated and compounding was difficult.

[Examples 7 to 9, Comparative Example 5] (CH_Three)_TwoS
99.825 mol% of iO units, (CH_Three) (CH_Two= C
H) 0.15 mol% of SiO units, (CH_Two= CH)
(CH_Three)_TwoSiO_1/2The unit consists of 0.025 mol%
Methyl vinyl polysiloxane 6 having an average degree of polymerization of 4000
5 parts, (CH_Three)_TwoSiO The unit is 99.95 mol%, (C
H_Two= CH) (CH_Three)_TwoSiO_1/2Unit is 0.05 mol%
Methylvinylpolysilo having an average degree of polymerization of 3000
35 parts of xane, specific surface area is 195m^Two/ G precipitated silica
(Nipsil Lp, manufactured by Nippon Silica Co., Ltd., silica is
Drying beforehand to reduce the adsorbed moisture to 0.5% by weight
40 parts, wetter and phosphor silicone
The mixture was mixed using a pressure kneader with the composition shown in Table 3 and
A corn rubber compound was obtained. The compounding temperature at this time is
It started at 25 ° C and reached 150 ° C. The required time is
About 25 minutes.

When a hydroxyl group-containing silicon compound having 10 silicon atoms was used as a wetter (Comparative Example 5), the precipitated silica was adsorbed to a water content of 6. without a drying step.
When used at 0% by weight (Example 9), a silicone rubber compound was obtained in the same manner.

The obtained silicone rubber compound 10
0.5 parts of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 parts, and press cure was performed at 170 ° C. for 10 minutes and post cure at 200 ° C. for 4 hours. Cured under the conditions to obtain a silicone rubber. Table 3 shows the physical property values.

[0052]

[Table 3]

As can be seen from the results shown in Table 3, when the silicon atom of the hydroxyl-containing silicon compound as a wetter contained 1 silicon atom.
In the case of zero (Comparative Example 5), the compound was sagged and the workability was poor.

Example 10 The same raw material composition as in Example 1 was continuously blended using a twin-screw mixer (trade name: TEM (diameter: 2 inches) manufactured by Toshiba Machine Co., Ltd.).

Feed rate of methyl vinyl siloxane 50 k
g / h, and fumed silica and 1,1,
A powder preliminarily mixed with 3,3-tetramethyldisiloxane-1,3-diol with a Henschel mixer is 21.5 k.
g / h and further, phosphorus siliconate was charged into the continuous twin-screw mixer at 0.05 kg / h.

The temperature at the mixer inlet was 25 ° C., and the temperature at the mixer outlet was 180 ° C. The residence time in the mixer was 3 minutes.

After cooling the obtained rubber compound to room temperature, a vulcanizing agent was added in the same manner as in Example 1, the sheet was vulcanized and molded, and the physical properties of the rubber were measured. Table 4 shows the results.

[0058]

[Table 4]

[Examples 11 to 15, Comparative Examples 6 and 7] (C
99.825 mol% of H ₃ ) ₂ SiO units, (CH ₃ )
0.15 mol% of (CH ₂ ＣＨCH) SiO units, (CH ₂ CH)
= CH) (CH ₃ ) ₂ SiO _1/2 unit is 0.025 mol%
Fumed silica having a specific surface area of 200 m ² / g (adsorbed water content: 0.3% by weight) (100 parts by weight of methyl vinyl polysiloxane having an average degree of polymerization of 4,000 and comprising Erosil 200 manufactured by Nippon Aerosil Co., Ltd.) 40 parts, 1,1,
3 parts of 3,3-tetramethyldisiloxane-1,3-diol and any of the tertiary amines and quaternary ammonium compounds were mixed in the composition shown in Tables 5 and 6 using a pressure kneader, and the mixture was mixed with a silicone rubber compound. Was manufactured. The compounding temperature at this time was started from 40 ° C. and reached 150 ° C. The time required was about 20 minutes.

For comparison, a silicone rubber compound was obtained in the same manner when no tertiary amine was blended (Comparative Example 6) and when a non-pressurized kneader mixer was used (Comparative Example 7).

Next, 0.5 part of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 100 parts of the obtained silicone rubber compound, and press cure was performed at 170 ° C. / 10 minutes, cured at 200 ° C. for 4 hours, to obtain a silicone rubber. The physical properties are shown in Tables 5 and 6.

[0062]

[Table 5]

[0063]

[Table 6]

As is evident from the results in Tables 5 and 6, a system to which neither a tertiary amine nor a quaternary ammonium compound was added was a compound having large plastic reversion and poor processability. In addition, the compression set was large and the characteristics were inferior. When the composition was compounded using a non-pressurized kneader mixer instead of the pressure kneader, the composition was not integrated and the compounding was difficult. On the other hand, by adopting the method of the present invention, a silicone rubber having easy rubber compounding and good rubber properties could be obtained.

[Examples 16 to 18, Comparative Example 8] (C
H_Three)_Two99.825 mol% of SiO units, (CH_Three)
(CH_Two= CH) SiO units 0.15 mol%, (CH_Two
= CH) (CH_Three)_TwoSiO_1/2Unit is 0.025 mol%
Methylvinylpolysilo having an average degree of polymerization of 4000
65 parts of xane, (CH_Three)_TwoSiO Unit is 99.95 mol
%, (CH_Two= CH) (CH_Three)_TwoSiO_1/2Unit is 0.0
Methyl vinyl with an average degree of polymerization of 3000 consisting of 5 mol%
35 parts of polysiloxane, specific surface area is 195 m^Two/ G sediment
Silica (manufactured by Nippon Silica Co., Ltd., trade name Nipsil Lp,
Silica is dried in advance and adsorbed moisture is 0.5 weight
40 parts, as a tertiary amine
Tetramethyl-guanidyl-propyl-trimethoxysi
0.1 part of run, weter pressurized kneader with the composition of Table 7
Was used to obtain a silicone rubber compound.
At this time, the compounding temperature is started from 25 ° C and up to 150 ° C.
Reached. The time required was about 25 minutes.

When a hydroxyl group-containing silicon compound having 10 silicon atoms was used as a wetter (Comparative Example 8), the precipitated silica was adsorbed to a water content of 6. without a drying step.
When used at 0% by weight (Example 18), a silicone rubber compound was obtained in the same manner.

The obtained silicone rubber compound 10
0.5 parts of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 parts, and press cure was performed at 170 ° C. for 10 minutes and post cure at 200 ° C. for 4 hours. Cured under the conditions to obtain a silicone rubber. Table 7 shows the physical property values.

[0068]

[Table 7]

As can be seen from the results shown in Table 7, when the silicon atom of the hydroxyl-containing silicon compound as a wetter was 1
In the case of No. 0 (Comparative Example 8), the compound was sagged and the surface was sticky, and the workability was poor.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 83/07 C08K 3/34 C08K 3/36 C08K 5/5415 C08L 83/04

Claims (5)

(57) [Claims] (A) The following general composition formula (1): R ¹ _a SiO _{(4-a) / 2} (1) wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group. , R ^{1 represents} 0.001 to 0.5 mol% of an alkenyl group. A is a positive number of 1.95 to 2.05.) (B) a reinforcing silica filler having a specific surface area of 50 m ² / g or more by a BET method, (C) a hydroxyl group-containing silicon compound having 5 or less silicon atoms, (D) a phosphorus siliconate, a tertiary amine and a quaternary amine. A method for producing a silicone rubber compound, comprising dispersing and mixing a component comprising one or more catalysts selected from quaternary ammonium compounds using a pressurized mixer or a continuous mixer. 2. A catalyst obtained by reacting n-tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide or tetramethylphosphonium hydroxide with hexamethylcyclotrisiloxane as a catalyst of the component (D). The method for producing a silicone rubber compound according to claim 1, wherein a phosphorus siliconate catalyst is used. 3. The silicone rubber compound according to claim 1, wherein tetramethyl-guanidyl-propyl-trimethoxysilane, diethyl-trimethyl-aminosilazane or tetramethylammonium hydroxide is used as the catalyst of the component (D). Method. 4. The method for producing a silicone rubber compound according to claim 1, wherein the dispersion and mixing step is started at a temperature of 100 ° C. or lower and is completed in a range of 150 to 200 ° C. 5. The method for producing a silicone rubber compound according to claim 1, wherein the water content of the reinforcing silica filler is 2% by weight or less.