JPH08157726A - Production of silicone rubber compound - Google Patents

Abstract

PURPOSE: To obtain a transparent silicone rubber which can give a silicone rubber compound reduced in crape hardening and having excellent storability and good processability without fail and have reduced compression set and good mechanical properties. CONSTITUTION: This rubber compound is prepared by mixing an organopolysiloxane represented by the general compositional formula: R<1> a SiO(4-a)/2 (wherein R<1> is an (un)substituted monovalent hydrocarbon group, provided that 0.001-0.5mol% of R<1> s are alkenyl groups; and (a) is a positive number of 1.95-2.05) with a reinforcing silica filler having a specific surface area of 50m<2> /g or above as measured by the BET method, a hydroxy silicon compound having five or more silicon atoms and at least one catalyst selected from among a phosphosiliconate, a tert. amine and a quat. ammonium compound with a pressure mixer or a continuous mixer.

Description

Detailed Description of the Invention

[0001]

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]

2. Description of the Prior Art When a silicone filler is added in a large amount to a silicone polymer, the composition has excellent physical properties such as tensile strength, tear strength, elongation and heat resistance. Is known to be.
However, in order to add a large amount of silica filler to the silicone polymer, it is necessary to add a large amount of wetter (dispersant) in order to improve the dispersibility of the silica filler.

Conventionally, as a wetter, the following formula HO [(CH₃)₂SiO]_xΑ, ω-siloxane diene having a degree of polymerization of 10 to 20 represented by H (x = 10 to 20)
Alls have been commonly used (US Pat. No. 3,79).
9, 962). In addition, RO [(CH₃)₂SiO]
_yH (R : Short-chain alkyl group, y = 3 to 5) α-alco
Xy-ω-siloxanol is also known, and
Samethyltrisiloxanediol and methoxyhexamethy
Antistrak with a mixture of rutriciloxanol
Char agents have also been proposed (US Pat. No. 3,925,2).
No. 85).

However, in the conventional wetter, if a little too much is added in order to reduce crepe hardening, the silicone rubber composition becomes sticky, the workability is deteriorated, and the mechanical properties of the cured product are lowered, so that the stickiness is suppressed. Therefore, if the addition amount is reduced, stickiness disappears, but there are problems such as remarkable crepe hardening.
When silica is mixed and dispersed and mixed, the wettability of silica is poor and the resulting compound becomes dull,
There was a problem that they would fall apart. Therefore, there has been a demand for the development of a wetter that has less crepe hardening, is not sticky, and improves the mechanical properties of a cured product.

In order to solve such a problem, the present inventor previously found that Japanese Patent Application Nos. 5-302409 and 6-431.
No. 95 and Japanese Patent Application No. 6-75318 have proposed a silicone rubber composition with a novel wetter compound. When a normal pressure closed type do mixer, which is generally used for compounding a silicone rubber compound, is used, Although the results of improving the above problems to a certain extent can be obtained to some extent, the process time until the expected physical properties were obtained and the vulcanized physical properties of the obtained rubber were still unsatisfactory. When a closed type pressure mixer such as a Banbury mixer or a pressure kneader is used, the compounding time can be shortened, but the process time to obtain the expected physical properties is long and the obtained rubber is I was still dissatisfied with the vulcanized physical properties.

The present invention has been made in order to improve the above-mentioned circumstances, and a silicone rubber composition which gives 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]

Means and Actions for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, (A) the following general composition formula (1) R ¹ _a SiO 2 _{(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 100 or more represented by a positive number of 2.05), (B) a reinforcing silica filler having a specific surface area of 50 m ² / g or more by the BET method, and (C) a silicon atom. Is a pressure-containing mixer or a continuous mixer containing 5 or less hydroxyl group-containing silicon compound, (D) phosphorus siliconate, one or more components selected from tertiary amine and quaternary ammonium compound. To produce a silicone rubber compound by dispersing and mixing Therefore, it was found that the crepe hardening is improved in a shorter time step than the conventional one, the increase in plasticity is small even after long-term storage, and the silicone rubber excellent in vulcanized physical properties can be obtained, and the present invention It was the eggplant.

The present invention will be described in more detail below. The present invention includes (A) the following general composition formula (1) R ¹ _a SiO 2 _{(4-a) / 2} (1) (wherein R ¹ is a substituent) Or an unsubstituted monovalent hydrocarbon group, but 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). An 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 the BET method, (C) a hydroxyl group-containing silicon compound having 5 or less silicon atoms, (D) ) A silicone rubber compound is manufactured by dispersing and mixing components consisting of one or more catalysts selected from phosphorus siliconate, tertiary amines and quaternary ammonium compounds with a pressure mixer or continuous mixer. Is.

Here, the organopolysiloxane as the component (A) used in the production of this silicone rubber compound is represented by the following general composition formula (1) R ¹ _a SiO 2 _{(4-a) / 2} (1) (wherein , R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and 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.

In the formula (1), R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and the carbon number thereof is preferably 1-10, more preferably 1-6. in this case,
0.001-0.5 mol% of alkenyl groups in all R ¹ groups
It is necessary to be contained at a ratio of, and more preferably 0.01 to 0.3 mol%. If the proportion of this alkenyl group is too low, the curability of the resulting composition is reduced, and if it is too high, the physical properties such as tensile strength, tear strength, and elongation of the obtained cured product are reduced. To do.
Examples of such alkenyl groups include vinyl groups,
Examples thereof include allyl group and butenyl group, and vinyl group is preferable.

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

It is necessary that a is a number in the range of 1.95 to 2.05, and more preferably 1.98 to 2.02.
Is. When a is outside the above range, the degree of polymerization 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 units constituting the organopolysiloxane are diorganosiloxane units, but triorganosiloxane units and SiO ₂ units are 1 mol in the organopolysiloxane. % May be included. The end of the molecular chain may be blocked with a hydroxyl group or a triorganosilyl group. Examples of the preferred molecular chain terminal include a dimethylvinylsilyl group, a trimethylsilyl group, a trivinylsilyl group, a dimethylhydroxysilyl group and the like. Furthermore, the degree of polymerization of the organopolysiloxane must be 100 or more, and preferably 100 to 100, in order to obtain a cured product of the composition having sufficient mechanical strength.
00, more preferably 2000 to 10,000.

Specific surface area as component (B) (BET method)
Examples of the reinforcing silica filler having a ratio of 50 m ² / g or more include fumed silica and precipitated silica, and these may be used alone or in combination of two or more. Particularly, in the transparency and the reinforcing property of the obtained silicone rubber composition, the specific surface area is 100 to 400 m ² /
Fumed silica with g is preferred. Further, 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.

The surface of these silica fillers may be treated with, for example, a chain organopolysiloxane, a cyclic organopolysiloxane or hexamethyldisilazane.

In this case, the water content of the reinforcing silica is preferably 2% by weight or less. If the amount of water is large, the process for obtaining preferable physical properties may be lengthened.

The amount of the silica filler compounded is 5 to 10 with respect to 100 parts by weight of the organopolysiloxane (A).
The proportion of 0 parts by weight is preferable, and more preferably 10 to 50.
Parts by weight. If the blending amount is too large or too small, the processability of the obtained silicone rubber composition is lowered, and the cured product obtained by curing the silicone rubber composition has sufficient tensile strength, tear strength, etc. In some cases, it may not have mechanical strength.

The hydroxyl group-containing silicon compound having 5 or less silicon atoms as the component (C) improves the dispersibility of the above organopolysiloxane and the reinforcing silica filler to give a silicone rubber compound having improved crepe hardening. It is intended 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 s} may be the same or different. In this case, as the monovalent hydrocarbon group for R ² , the same ones as those for R ¹ can be exemplified, but in particular, a methyl group, a vinyl group,
A 3,3,3-trifluoropropyl group is preferable from the viewpoint of more effectively exhibiting the effects of the present invention, and a methyl group is most preferable. R ³ represents a methyl group, a trimethylsiloxy group, a vinyl group or a trifluoropropyl group, and b represents 0, 1, 2 or 3 (however, 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 blending amount is less than 1% by weight, the activity of silica is strong,
If the crepe hardening is not improved and the amount is more than 30% by weight, the composition may become sticky or the waist may be dropped and the cost may increase.

The component (D) is a catalyst selected from phosphorus siliconate, tertiary amines and quaternary ammonium compounds. These catalysts may be used alone or in combination of two or more. You can Here, the phosphorus siliconate catalyst is obtained by reacting an organophosphorus compound and an organosiloxane, and for example, n-tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide or tetramethylphosphonium hydroxide is hexamethyl 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 to be transparent. And then 20m
It can be obtained by continuing the reaction for about 2 hours under the pressure of mHg. On the other hand, as the tertiary amine, tetramethyl-guanidyl-propyl-trimethoxysilane, diethyl-trimethyl-aminosilazane, and as the quaternary ammonium compound, tetramethylammonium hydroxide is preferably used. You can The catalyst of component (D) is an essential component for promoting the reaction between silica and a wetter and is an important component of the present invention.

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

To obtain the silicone rubber compound of the present invention, the above-mentioned organopolysiloxane, silica filler, hydroxyl group-containing silicon compound having 5 or less silicon atoms,
Then, a component consisting of one or two or more kinds of catalysts selected from phosphorus siliconate, tertiary amine and quaternary ammonium compound is blended and mixed by a pressure type mixer or a continuous mixer to produce. Other non-pressurized type mixers, open type mixers and the like have poor mixing and dispersibility, resulting in poor physical properties and long process time, so that the object of the present invention cannot be achieved.

In this case, a Banbury mixer, a pressure kneader, an intermix, etc. are exemplified as the pressure type mixer, and a biaxial mixer and a uniaxial mixer are exemplified as the continuous mixer. TEM (manufactured by Toshiba Machine Co., Ltd.), WP (manufactured by WelneR ¹ & Pfleidler) as a biaxial mixer, and Ko-Kneeder (B as a uniaxial mixer.
manufactured by uss) and the like.

The mixing and dispersing step is started at 100 ° C. or lower, more preferably 0 to 70 ° C., and 150 to 200 ° C.
It is desirable that the hydroxyl group-containing silicon compound having 5 or less silicon atoms as a wetter is selected from phosphorus siliconate, tertiary amine, and quaternary ammonium compound. Two or more kinds of catalysts can react with the silica filler effectively and quickly.

The water content of the reinforcing silica filler is preferably 2% by weight or less as described above, and if it exceeds 2% by weight, it takes time to heat up the composition,
In some cases, the shortening of the process time, which is the object of the present invention, cannot be achieved.

The silicone rubber compound should be
If desired, various compounding agents usually compounded with silicone rubber may be added. For example, ground 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 mica powder, fused silica powder and the like may be blended. In addition, pigments, dyes, antioxidants, antioxidants, antistatic agents, flame retardants (eg antimony oxide, chlorinated paraffin, etc.), thermal conductivity improvers (eg boron nitride, aluminum oxide, etc.) may be added as required. You may. These components can be dispersed and mixed together with the above 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, an organohydrogenpolysiloxane and a platinum group metal-based catalyst are used when the composition is cured by a hydrosilylation reaction, and a peroxide is used when the composition is peroxide-crosslinked. Known ones are used.

More specifically, in the case of curing by hydrosilylation reaction, an organohydrogenpolysiloxane and a platinum group metal-based catalyst are used as a curing agent,
It can be cured by heating at a temperature of 200 ° C. for 0.5 minutes to 5 hours. As the organohydrogenpolysiloxane used, the following average composition formula (2) R ⁴ _c H _d SiO _{(4-cd) / 2} (2) (wherein, R ⁴ is a substituted or unsubstituted carbon atom number 1) 10 represents a monovalent hydrocarbon group, 0 ≦ c <3 and 0 <d ≦ 3, and c + d is a number satisfying 1.0 to 3.0.)
And has two or more -SiH groups in the molecular chain. The —SiH group may be at the end of the molecular chain or may be in the middle. In the above average composition formula (2), R ⁴ includes the same ones as R ^1, and examples thereof include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, a phenyl group and a tolyl group. Examples thereof 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 organohydrogenpolysiloxane used is such that the ≡SiH group in the organohydrogenpolysiloxane is 0.5 to 3 mol per 1 mol of the alkenyl group in the organopolysiloxane of the component (A). Is preferable, and more preferably the amount is 1 to 2 mol.

Examples of the platinum group metal-based catalyst include platinum-based, palladium-based and rhodium-based catalysts, of which platinum-based catalysts are preferred. As such a platinum-based catalyst, for example, a fine powder metal platinum catalyst (for example, US Pat.
70150), chloroplatinic acid catalysts (for example, those described in US Pat. No. 2,823,218), platinum-hydrocarbon complex compounds (for example, those described in US Pat. No. 3,159,601 or US Pat. No. 3,159,662), Chloroplatinic acid-olefin complex compounds (see, for example, US Pat. No. 3516)
946), platinum-vinyl siloxane complexes (eg US Pat. No. 3,775,452 or US Pat. No. 3).
No. 814780) and the like. The amount used is usually 0.1 to 1000 ppm (platinum equivalent) with respect to the total amount of the organopolysiloxane (A) and the organohydrogenpolysiloxane.
More preferably, it is 1 to 100 ppm (platinum equivalent).

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, reaction of methylvinylcyclotetrasiloxane, acetylene alcohol, etc. A control agent 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 the organic peroxide is blended per 100 parts by weight of the organopolysiloxane. It is more preferably 0.05 to 1 part by weight. The silicone rubber composition thus obtained is usually 10 to 100 ° C. at 500 to 500 ° C.
It can be cured by heating for 2 seconds to 5 hours.

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

[0038]

EFFECTS OF THE INVENTION According to the present invention, it is possible to reliably produce a silicone rubber compound having improved crepe hardening, excellent storage stability, and good processability. By using this compound, the compression set is small, A transparent silicone rubber having good mechanical properties is obtained, which makes it suitable as a material for extrusion molding of, for example, 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, electric wires, and the like.

[0039]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the examples, “part” means “part by weight”.

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

For comparison, a silicone rubber compound was obtained in the same manner in the case where no phosphorus silicone was blended (Comparative Example 1) and the case where 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 a press cure of 170 ° C. It was cured under the conditions of / 10 minutes and post cure 200 ° C./4 hours to obtain a silicone rubber. The physical property values are shown in Table 1.

[0043]

[Table 1]

As is clear from the results shown in Table 1, the system in which phosphorus phosphonate was not added was a compound having a large plastic return and poor processability, and also had a large compression set and a poor physical property. When a non-pressurized kneader mixer was used 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, it is possible to obtain a silicone rubber which is easy to compound and has good rubber physical properties.

[Examples 4 to 6, Comparative Examples 3 and 4] (C
H _{3) 2} SiO units 99.825 mol%, (CH ₃₎
(CH ₂ ═CH) SiO unit is 0.15 mol%, (CH ₂ ═CH)
= CH) (CH ₃ ) ₂ SiO _1/2 0.025 mol% unit
To 100 parts of methylvinylpolysiloxane having an average degree of polymerization of 4000 and having a specific surface area of 195 m ² / g, precipitated silica (manufactured by Nihon Silica Co., Ltd., trade name Nipsil Lp, silica is preliminarily dried to remove the adsorbed moisture. 5 parts by weight) were mixed) 45 parts, 1,1,3,3-tetramethyldisiloxane-1,3-diol 2 parts and phosphorus siliconate in the composition shown in Table 2 using a pressure kneader. Then
A silicone rubber compound was produced. The compounding temperature at this time was started from 45 ° C and reached 160 ° C. The time required was about 25 minutes.

Obtained Silicone Rubber Compound 10
0.5 part of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 part, and press cure 170 ° C./10 minutes and post cure 200 ° C./4 hours. It was cured under the conditions to obtain a silicone rubber. The physical property values are shown in Table 2.

[0047]

[Table 2]

As is clear from the results in Table 2, the system in which phosphorus phosphonate was not added was a compound having a large plastic return and poor processability, and also had a large compression set and a poor physical property. In addition, when a non-pressurizing kneader mixer was used instead of the pressure kneader, the composition was not integrated, and the compounding was difficult.

[Examples 7-9, Comparative Example 5] (CH₃)₂S
99.825 mol% of iO unit, (CH₃) (CH₂= C
H) SiO unit is 0.15 mol%, (CH₂= CH)
(CH₃)₂SiO_1/2Unit consists of 0.025 mol%
Methyl vinyl polysiloxane 6 with an average degree of polymerization of 4000
5 copies, (CH₃)₂SiO The unit is 99.95 mol%, (C
H₂= CH) (CH₃)₂SiO_1/2Unit is 0.05 mol%
Methyl vinyl polysiloxane having an average degree of polymerization of 3000
35 parts xanthan, specific surface area 195 m²/ G precipitated silica
(Nippon Silica Co., Ltd., trade name Nipsil Lp, silica is
It was previously dried to make the adsorbed water content 0.5% by weight.
40 parts, wetter and phosphorus silicone
The mixture was mixed with the composition shown in Table 3 using a pressure kneader, and
A corn rubber compound was obtained. The compounding temperature at this time is
It started at 25 ° C and reached 150 ° C. Time required
It was about 25 minutes.

When a silicon compound having a hydroxyl group-containing silicon compound having 10 silicon atoms was used as a wetter (Comparative Example 5), the adsorbed water content of the precipitated silica was 6.
A silicone rubber compound was obtained in the same manner when used at 0% by weight (Example 9).

Obtained Silicone Rubber Compound 10
0.5 part of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 part, and press cure 170 ° C./10 minutes and post cure 200 ° C./4 hours. It was cured under the conditions to obtain a silicone rubber. The physical property values are shown in Table 3.

[0052]

[Table 3]

As can be seen from the results shown in Table 3, the silicon compound of the hydroxyl group-containing silicon compound as a wetter has 1
In the case of 0 (Comparative Example 5), the compound had sagging and the workability was poor.

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

Supply rate of methyl vinyl siloxane 50 k
g / h, and fumed silica and 1,1,
21.5k powder obtained by premixing 3,3-tetramethyldisiloxane-1,3-diol with a Henschel mixer
g / h, and further 0.05 kg / h of phosphorus siliconate were charged into the continuous twin-screw mixer.

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

After the obtained rubber compound was cooled 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. The results are shown in Table 4.

[0058]

[Table 4]

[Examples 11 to 15, Comparative Examples 6 and 7] (C
H _{3) 2} SiO units 99.825 mol%, (CH ₃₎
(CH ₂ ═CH) SiO unit is 0.15 mol%, (CH ₂ ═CH)
= CH) (CH ₃ ) ₂ SiO _1/2 0.025 mol% unit
Consisting of 100 parts of methylvinylpolysiloxane having an average degree of polymerization of 4000 and a specific surface area of 200 m ² / g fumed silica (adsorbed water content: 0.3% by weight) (Nippon Aerosil Co., Ltd., trade name Erosil 200) 40 copies, 1, 1,
Silicone rubber compound was prepared by mixing 3 parts of 3,3-tetramethyldisiloxane-1,3-diol and any one of a tertiary amine and a quaternary ammonium compound in a composition shown in Tables 5 and 6 using a pressure kneader. 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 a press cure of 170 ° C. It was cured under the conditions of / 10 minutes and post cure 200 ° C./4 hours to obtain a silicone rubber. The physical property values are shown in Tables 5 and 6.

[0062]

[Table 5]

[0063]

[Table 6]

As is clear from the results shown in Tables 5 and 6, the system in which neither the tertiary amine nor the quaternary ammonium compound was added was a compound having a large plastic reversion and poor processability, and had physical properties. However, the compression set was large and the characteristics were inferior. When a non-pressurized kneader mixer was used 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, it is possible to obtain a silicone rubber which is easy to compound and has good rubber physical properties.

[Examples 16 to 18, Comparative Example 8] (C
H₃)₂SiO unit is 99.825 mol%, (CH₃)
(CH₂═CH) SiO unit is 0.15 mol%, (CH₂
= CH) (CH₃)₂SiO_1/2Unit is 0.025 mol%
Methyl vinyl polysiloxane having an average degree of polymerization of 4000
65 parts of xane, (CH₃)₂SiO Unit is 99.95 mol
%, (CH₂= CH) (CH₃)₂SiO_1/2Unit is 0.0
Methyl vinyl with an average degree of polymerization of 3000, consisting of 5 mol%
35 parts polysiloxane, specific surface area 195 m²/ G
Silica Furu (manufactured by Nippon Silica Co., Ltd., trade name Nipsil Lp,
Silica is pre-dried and the adsorbed water content is 0.5 weight.
%) 40 parts as a tertiary amine
Tetramethyl-guanidyl-propyl-trimethoxyoxy
Pressurization kneader with run of 0.1 part and wetter with the composition of Table 7
To obtain a silicone rubber compound.
The compounding temperature at this time starts from 25 ° C and reaches 150 ° C.
Reached in The time required was about 25 minutes.

When a silicon compound having a hydroxyl group containing 10 silicon atoms was used as a wetter (Comparative Example 8), the adsorbed water content of the precipitated silica was 6.
A silicone rubber compound was obtained in the same manner when used at 0% by weight (Example 18).

Obtained Silicone Rubber Compound 10
0.5 part of 2,5-bis- (tert-butylperoxy) -2,5-dimethylhexane as a vulcanizing agent was added to 0 part, and press cure 170 ° C./10 minutes and post cure 200 ° C./4 hours. It was cured under the conditions to obtain a silicone rubber. The physical property values are shown in Table 7.

[0068]

[Table 7]

As can be seen from the results in Table 7, the number of silicon atoms in the hydroxyl group-containing silicon compound as a wetter is 1
No 0 (Comparative Example 8) had sagging in the compound and surface tackiness, resulting in poor workability.

Claims (5)

[Claims] (A) The following general composition formula (1) R ¹ _a SiO 2 _{(4-a) / 2} (1) (wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, , 0.001 to 0.5 mol% in R ¹ is an alkenyl group, and a is a positive number of 1.95 to 2.05.) An organopolysiloxane having an average degree of polymerization of 100 or more, (B) Reinforcing silica filler having a specific surface area by the BET method of 50 m ² / g or more, (C) hydroxyl group-containing silicon compound having 5 or less silicon atoms, (D) phosphorus siliconate, tertiary amine and quaternary A method for producing a silicone rubber compound, which comprises dispersing and mixing components consisting of one or more catalysts selected from primary ammonium compounds by a pressure mixer or a continuous mixer. 2. A catalyst obtained by reacting n-tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide or tetramethylphosphonium hydroxide with hexamethylcyclotrisiloxane as the component (D) catalyst. The method for producing a silicone rubber compound according to claim 1, wherein a phosphorus siliconate catalyst is used. 3. The production of a 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 mixing step is started at 100 ° C. or lower and is ended at 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.