JPH06306290A - Liquid silicone rubber composition and production - Google Patents

Abstract

PURPOSE:To provide the composition comprising an alkenylene group-containing polysiloxane, a Si-H group-containing polysiloxane, a-platinum group metal catalyst, carbon black, a specific silica and a specified organic Si compound, excellent in melt-flowability and giving good heat-resistant cured products. CONSTITUTION:The objective liquid silicone rubber composition capable of forming cured products excellent in heat resistance, excellent in melt-flowability, and capable of being fed into automatic extruders comprises (A) an alkenyl group-containing organopolysiloxane, (B) an organo hydrogen polysiloxane having at least two hydrogen atoms bound to a silicon atom, (C) a platinum group metal catalyst, (D) carbon black, (E) silica having a specific surface area of >=50m<2>/g, and (F) an organic silicon compound having at least an addition-curable functional group selected from an alkenyl group, a Si-H group, etc., and at least an adhesive functional group selected from an alkoxysilyl group, an epoxy group, an acid anhydride group, a peroxysilyl group, etc., in the molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an addition-curable liquid silicone rubber composition capable of forming a cured product having excellent fluidity and remarkably excellent heat resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Addition-curable silicone rubbers are used for various purposes, and it is desired to improve their heat resistance. Many methods are known as methods for improving the heat resistance of such silicone rubber, and examples thereof include cerium oxide, cerium hydroxide, cerium atom-containing heterosiloxane, iron oxide, zirconium oxide, titanium oxide, and quartz powder. A method of blending an inorganic filler is known. However, although this method can improve the heat resistance to some extent, it does not exceed 300% while maintaining sufficient elongation properties.
It was not sufficient to obtain heat resistance at the ° C level.

It is also known that the strength of the cured product and the high heat resistance can be obtained by blending carbon black, but the silicone rubber used in this case has a silanol group at the molecular end. Alternatively, it is a condensation-curing type silicone rubber that uses an organopolysiloxane blocked with a hydrolyzable silyl group as a base component,
It is not an addition-curable silicone rubber composition. That is, when carbon black is added to an addition-curable silicone rubber composition, the fluidity thereof is significantly impaired, and it is impossible to effectively supply the composition using, for example, an automatic discharge device.

Further, as a method for improving the fluidity when carbon black is added to an addition-curable silicone rubber composition, a method of using carbon black surface-treated with an organic titanium compound has been proposed. (Japanese Patent Application No. 4-212150). However, since the composition provided by this method is a Newtonian fluid having no thixotropic property, for example, when the composition is supplied by an automatic discharging device, the composition may flow out more than necessary from a nozzle, or after discharging. There is a risk of spillage beyond the desired range.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to form a cured product having high heat resistance and strength and to have appropriate thixotropy. An object of the present invention is to provide an addition-curable silicone rubber composition that can be effectively used.

[0006]

According to the present invention, (A) an alkenyl group-containing organopolysiloxane, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, (C) Platinum group metal catalyst, (D) carbon black, (E) specific surface area is 5
0 m ² / g or more silica, (F) at least one addition-curable functional group selected from the group consisting of an alkenyl group and a Si—H group in one molecule, an alkoxysilyl group, an epoxy group, an acid Provided is a liquid silicone rubber composition containing an organosilicon compound having at least one adhesive functional group selected from the group consisting of an anhydride group and a peroxysilyl group.

According to the present invention, the first mixing step of uniformly mixing the alkenyl group-containing organopolysiloxane (A) and the carbon black (D) with the organotitanium compound, and the organohydrogenpolysiloxane (B ), A platinum group metal-based catalyst (C) and an organosilicon compound (F) are mixed with the mixture obtained in the above step in a second mixing step, and the silica (E) having a specific surface area of 50 m ² / g or more. ) Is mixed in the first or second mixing step to provide a method for producing the liquid silicone rubber composition.

According to the present invention, further, the alkenyl group-containing organopolysiloxane (A) and carbon black (D) are mixed with hexamethyldisilazane and heat-treated at a temperature of 50 to 200 ° C. to obtain a first mixture. And a second mixing step in which the organohydrogenpolysiloxane (B), the platinum group metal-based catalyst (C) and the organosilicon compound (F) are mixed with the mixture obtained in the above step. Is 50
There is provided a method for producing the liquid silicone rubber composition, characterized in that m ² / g or more of silica (E) is mixed in the first or second mixing step.

[0009]

The (A) alkenyl group-containing organopolysiloxane (A) component has been conventionally used as a base component of an addition-curable silicone rubber composition. For example, the following average composition formula (1): R _a SiO _{(4-a) / 2} (1) In formula, R is an organic group couple | bonded with the silicon atom, These may be the same or different group, a is 1.9-2.4
Organopolysiloxanes represented by the formula are generally used.

In the above formula (1), R is an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group or a butenyl group. An alkenyl group, a phenyl group, an aryl group such as a xylyl group, a benzyl group, an aralkyl group such as a phenylethyl group, and a group in which a part or all of the hydrogen atoms of these groups are substituted with a halogen atom or the like,
Examples thereof include a chloromethyl group and a 3,3,3-trifluoropropyl group. In addition, it is necessary that these contain an alkenyl group. This alkenyl group may be present either at the end of the molecular chain or in the middle thereof. Here, the alkenyl group is preferably a vinyl group, and the groups other than the alkenyl group are preferably a methyl group and a phenyl group.

The above-mentioned organopolysiloxane may be linear or branched having RSiO _3/2 units or SiO _4/2 units. Furthermore, this organopolysiloxane has a viscosity at 25 ° C of 100-100,000.
It is preferable that it is within the range of cP in order to obtain a cured product having excellent workability and physical properties.

Typical examples of such organopolysiloxanes include those shown below.

[Chemical 1] [In the formula, R is as described above, and m and n are positive integers. The above-mentioned organopolysiloxane can be produced by a method known per se, for example, easily obtained by carrying out an equilibration reaction between the organocyclopolysiloxane and the hexaorganodisiloxane in the presence of an alkali or acid catalyst. be able to.

(B) Organohydrogen polysiloxa
Organohydrogenpolysiloxane emission component (B) is intended to act as a crosslinking agent, those having at least two hydrogen atoms bonded to silicon atoms in one molecule. That is, the cured product of the rubber elastic body is formed by the addition reaction (hydrosilation) between the SiH group in the organohydrogenpolysiloxane and the alkenyl group in the (A) organopolysiloxane.

This organohydrogenpolysiloxane is also known as the component (A) and is not limited in molecular structure and may be linear, cyclic or branched, for example.
Further, the hydrogen atom bonded to the silicon atom may be present at any position in the molecule.

Generally speaking, this organohydrogenpolysiloxane comprises octamethylcyclotetrasiloxane and / or tetramethylcyclotetrasiloxane and hexamethyldisiloxane which can serve as a terminal group, or
1,1-dihydro-2,2 ', 3,3'-a silicon compound containing a tetramethyldisiloxane unit, in the presence of a catalyst such as sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid, -10 ~ 40 ℃ Manufactured by equilibrating with.

In the present invention, the component (B) is
It is used in an amount such that the silicon atom-bonded hydrogen atoms are 0.4 to 5.0 mol, particularly 0.8 to 2.0 mol, per 1 mol of the alkenyl group of the component (A). If this amount is less than the above range, the obtained cured product will have a low crosslink density, which may adversely affect the heat resistance. On the other hand, if the amount is larger than the above range, there may be a problem of foaming due to the dehydrogenation reaction, and also the heat resistance may be adversely affected.

The (C) platinum group metal-based catalyst (C) component is a catalyst for promoting the hydrosilation of the (A) component and the (B) component to form a cured product promptly. Examples include platinum-based, palladium-based, and rhodium-based ones. Generally, platinum-based ones are used, such as platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid and olefins. ,aldehyde,
A complex with vinyl siloxane or acetylene alcohol is preferably used. The addition amount of the component (C) may be set according to the desired curing speed, but usually,
0.1 to 1000 pp in terms of catalyst metal for component (A)
m may be in the range of 1 to 200 ppm.

(D) Carbon Black This component has the functions of improving the physical strength of the cured product and also improving the heat resistance. Carbon blacks are generally classified into furnace blacks, acetylene blacks, lamp blacks, thermal blacks, channel blacks and the like according to the production method thereof, but in the present invention, acetylene blacks are particularly preferably used. That is, carbon black other than acetylene black is usually unsuitable because it contains a large amount of sulfur, amine and the like, which causes curing inhibition. However, even carbon blacks other than acetylene black can be effectively used as long as the content of sulfur, amine, etc. is reduced by appropriate treatment. Further, in the present invention, the BET specific surface area of carbon black is preferably 10 m ² / g or more from the viewpoint of the physical reinforcing effect. Carbon blacks particularly suitable for the present invention are commercially available, for example, "Denka Black" (trade name) manufactured by Denki Kagaku Co., Ltd. and "Ketjen Black EC" (trade name) manufactured by Lion Corporation.

In the present invention, the component (D) is (A)
It is preferred to use 5 to 100 parts by weight, especially 10 to 30 parts by weight, per 100 parts by weight of the components. If it is less than 5 parts by weight, the effect of improving heat resistance and mechanical strength will not be sufficiently exhibited, and if it is used in excess of 100 parts by weight, the reinforcing property and heat resistance will be sufficiently improved. However, the liquidity of the product becomes poor, and there is a tendency of causing problems in practicality.

(E) Silica fine powder In the present invention, the component (E) has a specific surface area of 50 m ²
/ G or more of silica fine powder is used.
It is added to reinforce the cured product, that is, to impart mechanical strength and to control the thixotropy of the composition. Usually, such silica fine powder is used in an amount equal to or less than the blending amount of the carbon black, and particularly (A) component 10
Used in an amount of 1 to less than 20 parts by weight per 0 parts by weight. If the blending amount is larger than that of carbon black or is 20 parts by weight or more, the reinforcing effect tends to be large, but the heat resistance tends to decrease. On the other hand, if the amount is less than 1 part by weight, the composition cannot be provided with appropriate thixotropy, and as a result, the composition does not exhibit satisfactory fluidity and, for example, the composition may be supplied using an automatic discharge device. Difficult to do.

In the present invention, as the silica fine powder, either hydrophilic silica or hydrophobic silica can be used. Aerosil 1 as hydrophilic silica
30,200, 300 (Nippon Aerosil, Degussa), Ca
bosil MS-5, MS-7 (Cabot), Rheorosil QS-102,
103 (Tokuyama Soda), Nipsil LP (Nippon Silica)
Etc. As the hydrophobic silica, Aerosil
R-812, R-812S, R-972, R-974 (manufactured by Degussa), Rheor
Examples include osil MT-10 (manufactured by Tokuyama Soda Co., Ltd.) and Nipsil SS series (manufactured by Nihon Silica Co., Ltd.).

(F) Organosilicon Compound In the present invention, an organosilicon compound having an addition-curable functional group and an adhesive functional group in the molecule is used as the component (F). This organosilicon compound improves the adhesiveness of the obtained cured product to various adherends,
By coexisting with the fine powder silica of the component (E),
It has a great influence on the control of thixotropy.

Here, the addition-curable functional group is, as described above, a SiH group and an alkenyl group. Due to the presence of such a group, the organosilicon compound of this component (F) is incorporated into the cured product and adhered. And the effect of thixotropic control are stably expressed. The adhesive functional group is selected from an alkoxysilyl group, an epoxy group, an acid anhydride group and a peroxysilyl group. In the present invention, a trialkoxysilyl group and an epoxy group are particularly preferable. Most preferably used as the organosilicon compound of the component (F) having these functional groups, but not limited to, 1,5-dihydrogen-1,3,5,7 -Tetramethyl-
3-trimethoxysilylethyl-7-glycidylpropyl tetrasiloxane, bis (trimethoxysilylpropyl)
Allyl isocyanurate, 1,5-dihydrogen-1,3,
5,7-Tetramethyl-3-trimethoxysilylethyl-
7- (γ-methacryloxypropyl) tetrasiloxane, 3,5,7-trihydrogen-1,3,5,7-tetramethyl-1-glycidylpropyltetrasiloxane, 3,5,7
-Trihydrogen-1,3,5,7-tetramethyl-1-trimethoxysilylethyltetrasiloxane and the like can be mentioned.

In the present invention, the organosilicon compound as the component (F) is 0.1 to 10 per 100 parts by weight of the component (A).
It is used in an amount of parts by weight, especially 0.1 to 5 parts by weight. If it is less than 0.1 part by weight, the effect of improving the adhesiveness and the effect of controlling the thixotropy are not sufficient, and if it is used in excess of 10 parts by weight, the heat resistance of the cured product may be adversely affected. .

Other Compounding Agents In the present invention, various compounding agents known per se can be added and mixed within a range not impairing the object of the present invention such as improvement of fluidity. For example, cerium oxide, cerium hydroxide, zinc carbonate, manganese carbonate, heat resistance or flame retardant improver such as benzotriazole, vinyl group-containing organopolysiloxane such as vinylcyclotetrasiloxane, triallyl isocyanurate, alkyl maleate, Acetylene alcohol and these silanes,
It is also possible to add a curing control agent such as a siloxane modified product, hydroperoxide, or tetramethylethylenediamine.

Production of Liquid Silicone Rubber Composition The liquid silicone rubber composition of the present invention containing the above-mentioned components is basically the same as the carbon black described above.
(D) is mixed with the base polymer alkenyl group-containing organopolysiloxane (A) (first mixing step), and then other components are uniformly mixed with this mixture (second mixing step). Manufactured by.

First mixing step: When the carbon black (D) and the alkenyl group-containing organopolysiloxane (A) are mixed, the surface treatment of the carbon black is performed, and in order to disperse the carbon black uniformly, an organotitanium compound is used. Are mixed at the same time. That is, by mixing the organotitanium compound and subjecting the surface of the carbon black to the surface treatment, the fluidity of the composition is significantly improved.

Examples of such organic titanium compounds include tetraethyl titanate, tetraisopropyl titanate, tetra n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate,
Diethoxytitanium acetylacetonate, titanium diacetylacetonate, titanium octylglycate, titanium lactate, titanium lactate ethyl ester, and titanic acid esters such as partial hydrolysis-condensation products thereof, titanium partially alkoxylated chelate compounds, titanium chelate compounds. Examples thereof include titanium silicate esters and chelated products thereof.

The organotitanium compound is usually the component (A), though it varies depending on the blending amount of the carbon black (D).
It is added in an amount of 0.01 to 5 parts by weight, particularly 0.05 to 2 parts by weight, per 100 parts by weight. If less than 0.01 parts by weight,
The fluidity of the composition becomes unsatisfactory, and even if the composition is used in an amount larger than 5 parts by weight, further improvement in fluidity is not observed, and on the contrary, the heat resistance of the cured product tends to be impaired. It is also disadvantageous. The mixing using the organic titanium compound is usually performed at room temperature (about 25 ° C.).

Further, instead of using the organic titanium compound,
Hexamethyldisilazane and water can also be used. That is, hexamethyldisilazane is a surface treatment agent, and water causes hydrolysis of hexamethyldisilazane, and the surface treatment of carbon black with hexamethyldisilazane is rapidly performed. This hexamethyldisilazane is generally used in an amount of 0.1 to 1 per 100 parts by weight of the component (A).
It is preferably used in an amount of 0 parts by weight, especially 1 to 5 parts by weight. Water is preferably used in an amount of 10 parts by weight or less, particularly 1 to 5 parts by weight. The mixing of hexamethyldisilazane and water is performed at a temperature of 50 to 200 ° C. in order to effectively perform the surface treatment of carbon black.

Second mixing step: The mixture of the carbon black surface-treated with an organotitanium compound or hexamethyldisilazane and the organopolysiloxane of component (A) contains the remaining components (B), (C), ( Mixed with E), (F) and other optional ingredients. In this case, the fine silica powder of component (E) is the first
May be added in the mixing step, or a part thereof may be added in the first mixing step and the remaining amount may be added in the second mixing step. Generally, addition in the first mixing step is preferred.

Liquid Silicone Rubber Composition The liquid silicone rubber composition of the present invention thus obtained is rapidly cured by heating to form an elastomer-like cured product. This cured product is super heat resistant and
Has rubber elasticity for a long time even at a high temperature of ~ 300 ° C,
It also has excellent adhesion to various substrates.

Further, this composition has a low viscosity and can be effectively supplied by an automatic ejector or the like even when it contains carbon black to the extent that sufficient mechanical strength and heat resistance are exhibited. It has such thixotropy. Therefore, this composition is applied to a so-called FIPG (Formed In P) using a transport pump and a coating robot.
It can be applied and cured by a method called lace gasket) method, and can be extremely effectively used as, for example, a sealant or an adhesive.

The curable composition of the present invention generally comprises (A)
Ingredients and (B) and (C) ingredients are packaged separately, and (D) to (F) ingredients are stored together in any of these, and both are mixed when actually used. It is preferable.
In this case, the mixture in which components (D) to (F) are mixed is
The fluidity has already been improved, and the excellent advantages of the present invention have been realized.

[0035]

EXAMPLES In the following specific examples, the viscosity is a value measured at 25 ° C. In addition, since Examples 1 to 6 and Comparative Examples 1 to 8 evaluate the fluidity of the compositions, the compounding of the curing catalyst (component (C)) that does not affect the fluidity or the viscosity was omitted. .

Example 1 100 parts by weight of straight-chain dimethylpolysiloxane (viscosity 5,000 cSt) in which both ends of the molecular chain were blocked with dimethylvinylsilyl groups 20 parts by weight of carbon black (Denka Black HS-100 manufactured by Denki Kagaku KK) 5 parts by weight of silica fine powder (specific surface area 110 m ² / g, Aerosil R-972 manufactured by Nippon Aerosil Co., Ltd.) were charged into a universal stirrer, mixed for 30 minutes at room temperature and atmospheric pressure, and then kneaded with three rolls to form a paste. A composition was obtained. To 100 parts by weight of this composition, 0.35 part by weight of tetraethoxide titanium (IV) was added, and the mixture was again stirred for 30 minutes at room temperature and normal pressure using a universal stirrer to obtain a titanium-treated base.

Next, 100 parts by weight of the above titanium-treated base was added with 2 parts by weight of methylhydrogenpolysiloxane (viscosity 11.5 cSt) having both ends of the molecular chain blocked with dimethylhydrogensilyl groups 1,5-dihydrogen-1. 1,3,5,7-Tetramethyl-3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane 1 part by weight bis (trimethoxysilylpropyl) allyl isocyanurate 1 part by weight was added at room temperature / 700 mmHg. A liquid silicone rubber composition was prepared by mixing for 10 minutes.

The viscosity of this composition was measured using a rotational viscometer.
The viscosities at 4 rpm and 20 rpm were measured and the thixo-coefficient (viscosity at 4 rpm / viscosity at 20 rpm) was calculated. Also, using the automatic discharge device AS-7 manufactured by Iwashita Engineering, discharge pressure 1.5kgf / cm ² , nozzle inner diameter
The composition prepared above was injected onto a 1 mm groove drawn in a circle with a diameter of 10 cm under the conditions of 1.6 mm, nozzle height 1.5 mm, and nozzle moving speed 3 m / min, and after 10 minutes Was observed. The above experimental results are shown in Table 1.

Example 2 A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that the amount of silica fine powder used was changed to 2 parts by weight, and the viscosity was measured by a rotary viscometer and automatically measured in the same manner. The ejection property was evaluated using an ejection device. The results are shown in Table 1.
It was shown to.

Example 3 A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that the amount of fine silica powder used was changed to 10 parts by weight, and the viscosity was measured by a rotary viscometer and automatically measured in the same manner. The ejection property was evaluated using an ejection device. The results are shown in Table 1.

Example 4 Of 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that the compounding amount was changed to 0.5 part by weight, and the viscosity was measured by a rotary viscometer and the automatic discharge device was used in the same manner. The dischargeability was evaluated. The results are shown in Table 1.

Example 5 Of 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that the compounding amount was changed to 2 parts by weight, and the viscosity was measured by a rotary viscometer and the dischargeability using an automatic discharge device was similarly measured. Was evaluated. The results are shown in Table 1.

Example 6 A paste-like composition was prepared in exactly the same manner as in Example 1. To 100 parts by weight of this composition, 4 parts by weight of hexamethyldisilazane and 2 parts by weight of water were added, and the mixture was stirred for 2 hours at 170 ° C./700 mmHg using a universal stirrer to obtain a heat-treated base. Example 1 except that this heat treated base was used instead of the titanium treated base.
A liquid silicone rubber composition is prepared in exactly the same manner as
In the same manner, the viscosity was measured by a rotational viscometer and the ejection property was evaluated using an automatic ejection device. The results are shown in Table 1.

Comparative Example 1 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate were added. A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that it was not compounded at all, and the viscosity was measured by a rotary viscometer and the dischargeability was evaluated using an automatic discharger in the same manner. The results are shown in Table 1.
It was shown to.

Comparative Example 2 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate were added. A liquid silicone rubber composition was prepared in exactly the same manner as in Example 6 except that no compounding was performed, and the viscosity was measured by a rotational viscometer and the dischargeability was evaluated using an automatic discharger in the same manner. The results are shown in Table 1.
It was shown to.

Comparative Example 3 An untreated pasty composition was used in place of the titanium treated base and 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl. A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that -7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate were not added at all, and a rotational viscometer was similarly prepared. The viscosity was measured and the dischargeability was evaluated using an automatic discharger. The results are shown in Table 1.

Comparative Example 4 A liquid silicone rubber composition was prepared in the same manner as in Example 1 except that an untreated paste-like composition was used instead of the titanium-treated base, and the same was measured by a rotational viscometer. The viscosity was measured and the ejection property was evaluated using an automatic ejection device. The results are shown in Table 1.

Comparative Example 5 A titanium treated base was prepared without the use of finely divided silica and 1,5-dihydrogen-1,3,5,7-tetramethyl-
A liquid silicone rubber composition was prepared in exactly the same manner as in Example 1 except that 3-trimethoxysilylethyl-7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate were not added at all, and Similarly, the viscosity was measured with a rotational viscometer and the dischargeability was evaluated using an automatic discharge device. The results are shown in Table 1.

Comparative Example 6 A liquid silicone rubber composition was prepared in the same manner as in Example 1 except that a titanium-treated base was prepared without using finely divided silica, and this base was used. The viscosity was measured with a rotational viscometer and the dischargeability was evaluated using an automatic discharger. The results are shown in Table 1.

Comparative Example 7 An untreated pasty composition was used in place of the titanium treated base and 1,5-dihydrogen-1,3,5,7-tetramethyl-3-trimethoxysilylethyl. A liquid silicone rubber composition was prepared in exactly the same manner as in Example 6 except that -7-glycidylpropyltetrasiloxane and bis (trimethoxysilylpropyl) allyl isocyanurate were not added at all, and a rotational viscometer was similarly prepared. The viscosity was measured and the dischargeability was evaluated using an automatic discharger. The results are shown in Table 1.

Comparative Example 8 A liquid silicone rubber composition was prepared in the same manner as in Example 6 except that a titanium-treated base was prepared without using finely divided silica, and this base was used. The viscosity was measured with a rotational viscometer and the dischargeability was evaluated using an automatic discharger. The results are shown in Table 1.

[0052]

[Table 1]

The thixotropy coefficient is a viscosity of _{4 rpm} / viscosity of _{20 rpm.}
Is the viscosity ratio.

Example 9 Liquid silicone rubber composition 100 prepared in Example 1
To 0.4 parts by weight of Surfynol 61 0.2 parts by weight of vinyl siloxane complex of chloroplatinic acid (platinum content 1% by weight) was added and mixed in a universal mixer for 10 minutes at room temperature / 700 mmHg. A curable composition was prepared. This composition is 120
℃ / 10 minutes heating to form a 2mm thick sheet, 300 ℃
Left in the atmosphere. After standing for a certain period of time, hardness, elongation and tensile strength were measured according to JIS C-2123. The results are shown in Table 2.

[0055]

[Table 2]

The hardness was measured using a JIS K-6301 A-type hardness spring type tester.

[0057]

EFFECT OF THE INVENTION The silicone rubber composition of the present invention can form a cured product having excellent heat resistance and is excellent in fluidity. For example, it has a low viscosity and thixotropy so that it can be supplied by an automatic discharging device. have.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaya Arakawa No. 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (3)

[Claims] 1. (A) an alkenyl group-containing organopolysiloxane, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, (C) a platinum group metal-based catalyst, ( D) carbon black, (E) silica having a specific surface area of 50 m ² / g or more, (F) at least one addition-curable functional group selected from the group consisting of alkenyl groups and Si-H groups in one molecule A liquid silicone rubber composition comprising a group and an organosilicon compound having at least one adhesive functional group selected from the group consisting of an alkoxysilyl group, an epoxy group, an acid anhydride group and a peroxysilyl group. 2. A first mixing step of uniformly mixing an alkenyl group-containing organopolysiloxane (A) and carbon black (D) with an organotitanium compound, an organohydrogenpolysiloxane (B) and a platinum group metal. The second mixing step of mixing the system catalyst (C) and the organosilicon compound (F) with the mixture obtained in the above step, wherein the silica (C) having a specific surface area of 50 m ² / g or more is 1
Alternatively, the method of producing the liquid silicone rubber composition according to claim 1, wherein the liquid silicone rubber composition is mixed in the second mixing step. 3. A first mixing step in which an alkenyl group-containing organopolysiloxane (A) and carbon black (D) are mixed with hexamethyldisilazane and heat-treated at a temperature of 50 to 200 ° C .; A second mixing step of mixing the genpolysiloxane (B), the platinum group metal-based catalyst (C) and the organosilicon compound (F) with the mixture obtained in the above step, and having a specific surface area of 50 m ² / g. The above silica (C) is the first
Alternatively, the method of producing the liquid silicone rubber composition according to claim 1, wherein the liquid silicone rubber composition is mixed in the second mixing step.