JPH08208994A - Liquid silicone rubber composition and production thereof - Google Patents

Abstract

PURPOSE: To obtain a composition excellent in flowability and curability and having. satisfactory viscosity stability in storage by compounding an organopolysiloxane with a reinforcing silica filler, a condensation catalyst, a specific compound, an organohydrogenpolysiloxane, and a platinum catalyst. CONSTITUTION: This composition comprises an organopolysiloxane having two or more Si-bonded alkenyl groups per molecule, a reinforcing silica filler having a specific surface area (BET method) of 50m/g<2> or larger, a condensation catalyst, a compound represented by formula I or II, an organohydrogenpolysiloxane having two or more Si-bonded hydrogen atoms per molecule, and a platinum catalyst. In the formulae, R<1> is methyl, trnmethylsiloxy, vinyl, or trifluoropropyl.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention not only excels in fluidity and curing characteristics, but also has good viscosity stability during storage, and is particularly suitable for injection molding using an injection molding machine. The present invention relates to a silicone rubber composition and a method for producing the same.

[0002]

When a large amount of a reinforcing silica filler is added to a silicone polymer, the composition has excellent physical properties such as tensile strength, tear strength, elongation and heat resistance. It is known that However, in order to add a large amount of silica filler to the silicone polymer, it is necessary to add a large amount of dispersant (wetting agent) in order to improve the dispersibility of the silica filler.

Conventionally, as a wetter, an α, ω-siloxane diol having a degree of polymerization of 10 to 20 represented by the following formula HO [(CH ₃ ) ₂ SiO] _x H (x = 10 to 20) is generally used. (US Pat. No. 3,799)
962).

In addition, RO [(CH ₃ ) ₂ SiO] _y H
(R: short-chain alkyl group, y = 3 to 5) α-alkoxy-ω-siloxanol is also known, and an anti-sugar using a mixture of hexamethyltrisiloxanediol and methoxyhexamethyltrisiloxanol. Lacture agents have also been proposed (US Pat. No. 3,925,285). However, when a silicone oil having a hydroxyl group at the terminal as described above is used as a wetter, it is possible to mix a large amount of a silica filler into a silicone polymer, but the resulting silicone polymer composition has thixotropic properties. The composition has a high viscosity and is not suitable for injection molding because it has no fluidity when molded.

Apart from the above silicone oil, hexamethyldisilazane is also known as a wetter for liquid silicone rubber compositions. However, a liquid silicone rubber composition obtained by using hexamethyldisilazane as a wetter has good fluidity and can be suppressed in viscosity, but by an amine by-produced when hexamethyldisilazane is compounded, There were problems such as poor curability and thickening during storage.

The present invention has been made in view of the above circumstances, and provides a liquid silicone rubber composition which is excellent not only in fluidity and curing characteristics but also in viscosity stability during storage, and a method for producing the same. The purpose is.

[0007]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of earnest studies to achieve the above object, the present inventor has found that (a) two or more alkenyl groups bonded to a silicon atom in one molecule. An organopolysiloxane having (b)
Reinforcing silica filler having a specific surface area (BET method) of 50 m ² / g or more, and (e) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, and (f) platinum. A silanol group-containing siloxane (d) represented by the following general formula (1) or (2), and a silanol group of this siloxane and the above silica filling are added to an addition reaction curable liquid silicone rubber composition containing a system catalyst as a main component. The addition of a condensation catalyst (c) for condensing the silanol groups on the surface of the agent, in this case, particularly when mixing part or all of the component (a) and all of the component (b), the condensation Catalyst (c) and above siloxane (d)
It was found that it is effective to add and blend.

[0008]

Embedded image (However, in the formula, R ¹ is a methyl group, a trimethylsiloxy group,
A vinyl group or a trifluoropropyl group is shown. )

That is, an organopolysiloxane as the component (a), a silica filler as the component (b), and a specific silanol group-containing siloxane compound represented by the above formula (1) or (2) as the component (d). The surface silanol group of the silica filler and the formula (1) or (2) by blending with the condensation catalyst of the component (c)
By condensing with a silanol group of the compound of (1), which occurs when a conventionally known silicone oil having a hydroxyl group at a terminal is used as a wetter, thixotropy is exerted on the obtained composition and the viscosity is increased. There is a problem that the composition is not suitable for injection molding because it has no fluidity, and when hexadimethyldisilazane is used instead of the conventional silicone oil, the fluidity of the obtained composition is good. The curing properties are poor, and the storage stability of the viscosity is also reduced, solving any of the problems, and significantly improving the curing properties without impairing the good fluidity of the liquid silicone rubber composition, In addition, the viscosity increase of the silicone rubber composition during storage is suppressed, and further, the siloxane compound of the above formula (1) or (2) has a high silanol group activity. , And finding that those also give the advantage of compounding of the filler such as silica is likely very performed, the present invention has been accomplished.

Therefore, according to the present invention, (a) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule, and (b) a specific surface area (BET method) of 50.
m ² / g or more reinforcing silica filler, (c) condensation catalyst,
(D) a compound represented by the above general formula (1) or (2),
(E) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule,
(F) In producing a liquid silicone rubber composition containing a platinum-based catalyst and this silicone rubber composition, when a part or all of the above component (a) and all of the component (b) are mixed, Provided is a method for producing a liquid silicone rubber composition, which comprises blending the components (c) and (d).

The present invention will be described in more detail below. The organopolysiloxane of the component (a) of the present invention is the main component of the silicone rubber composition of the present invention, and the organopolysiloxane of the component (a) is 1 It is necessary to have at least two silicon atom-bonded alkenyl groups in the molecule.

The organopolysiloxane of component (a)
The following average composition formula (3) R _aSiO_{(4-a) / 2} What is shown by (3) is preferably used.

Where R Is the number of carbon atoms bonded to the silicon atom
1-12, especially 1-8, unsubstituted or substituted monovalent hydrocarbon radicals
And, for example, methyl, ethyl, propyl, isopropyl
Ru, butyl, pentyl, neopentyl, hexyl, hep
Alky such as chill, octyl, nonyl, decyl, dodecyl
Group, cyclopentyl, cyclohexyl, cyclohepti
Cycloalkyl groups such as vinyl, allyl, propene
Le, isopropenyl, butenyl, isobutenyl, hex
Alkenyl groups such as ru, cyclohexyl, phenyl, tri
Aryl groups such as ru, xylyl, naphthyl and biphenyl,
Benzyl, phenylethyl, phenylpropyl, methyl
Water in aralkyl groups such as benzyl and these hydrocarbon groups
Some or all of the elementary atoms are halogen sources such as F, Cl, Br.
Chloromethyl group substituted with a child or cyano group
Lomoethyl group, 3,3,3-trifluoropropyl group,
Examples include 3-chloropropyl group and cyanoethyl group.
It

In this case, in the organopolysiloxane, at least two of the organic groups represented by R are alkenyl groups, and preferably 0.001 to 5 of all R groups.
Mol%, more preferably 0.01 to 2 mol% is an alkenyl group. If the proportion of alkenyl groups is too low, the curability of the resulting composition will be reduced, and if it is too high, the physical properties such as tensile strength, tear strength and elongation will be reduced. The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be present in both.

In the above formula (3), a is 1.65 to
It is a positive number of 2.35, preferably 1.8 to 2.2, and the molecular structure of this organopolysiloxane is basically preferably linear, and has alkenyl groups at both ends of the molecular chain. However, it may have a branched structure in part. The organopolysiloxane preferably has its molecular chain terminal blocked with a triorganosilyl group such as a trivinylsilyl, methyldivinylsilyl, dimethylvinylsilyl or trimethylsilyl group.

Although the molecular weight of the above organopolysiloxane is appropriately selected, it has a viscosity at 25 ° C. of 100 to 300,000 centipoise from the viewpoint of being cured into a rubber-like elastic body and providing a liquid silicone rubber composition. It is particularly preferably 1,000 to 100,000 centipoise.

The specific surface area (BET) of the component (b) of the present invention
Examples of the reinforcing silica filler having a method of 50 m ² / g or more include fumed silica, pyrogenic silica, precipitated silica, etc. These may be used alone or in combination of two or more. . Further, those silica fillers may be those whose surface is treated with, for example, a chain organopolysiloxane, a cyclic organopolysiloxane, or an organosilazane such as hexamethyldisilazane.

The silica filler of the component (b) of the present invention is B
Although requiring specific surface area by the ET method is 50 m ² / g or more, particularly, the transparency of the obtained silicone rubber composition, the specific surface area in the reinforcement 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, reinforcing and sedimentable silica having a specific surface area of 50 to 800 m ² / g is particularly desirable.

The amount of the silica filler compounded is 5 to 100 parts by weight of the organopolysiloxane of the component (a).
The proportion of 100 parts by weight is preferable, and more preferably 10 to 10.
60 parts by weight. If the blending amount is too large or too small, the moldability of the obtained silicone rubber composition may be reduced, and the cured product obtained by curing the silicone rubber composition may have sufficient tensile strength and tear strength. It may not have mechanical strength such as strength.

According to the present invention, when the organopolysiloxane as the component (a) and the silica filler as the component (b) are blended, a condensation catalyst as the component (c) and a compound (wetter) as the component (d) below are used. And ()
The addition of the component condensation catalyst markedly improves the fluidity of the silicone rubber composition.
On the other hand, when the component (c) is not added, the fluidity of the obtained silicone rubber composition is significantly impaired,
Injection molding becomes impossible. Such a condensation catalyst is not particularly limited as long as it promotes the condensation of the silanol group on the surface of silica and the silanol group of the component (d) of the present invention described later, and examples thereof include ammonia, aqueous ammonia, and tetrabutyl. Ammonium salts such as ammonium hydroxide, phosphorus-siliconate salts shown below, basic compounds such as potassium-siliconate salts shown below, tin octylate, tin compounds such as dibutyltin dilaurate, tetrabutyl titanate, etc. Titanium compounds, zinc compounds such as zinc octylate and zinc naphthylate are used, and among these, ammonia, ammonia water and the like are preferably used.

[0021]

[Chemical 4]

The content of the condensation catalyst of the above-mentioned component (c) is 0.005 to 1 part by weight relative to 1 part by weight of the following component (d),
It is preferably 0.01 to 0.8 parts by weight. If the blending amount is too small, the resulting composition may not have sufficient fluidity, and if the blending amount is too large, the curability of the composition and the mechanical properties of the cured product may be adversely affected. .

The component (d) of the present invention is an organosiloxane compound having a silanol group represented by the following formula (1) or (2), and it is a wetter when the components (a) and (b) are mixed. Is blended with the condensation catalyst of component (c) above, whereby the curability, fluidity and viscosity of the silicone rubber composition of the present invention are significantly improved.

[0024]

Embedded image (However, in the formula, R ¹ is a methyl group, a trimethylsiloxy group,
A vinyl group or a trifluoropropyl group is shown. )

Here, the compound represented by the above formula (1) can be obtained by a known method, for example, 1,1,1,
3,5,7,7,7-octamethyltetrasiloxane,
3,5-bis (trimethylsiloxy) -1,1,1,
7,7,7-hexamethyltetrasiloxane, 1,1,
1,7,7,7-hexamethyl-3,5-divinyltetrasiloxane, 3,5-bis (trifluoropropyl)
-1,1,1,7,7,7-hexamethyltetrasiloxane, 1,1,1,3,7,7,7-heptamethyl-5
It can be obtained by a method such as hydrolyzing vinyltetrasiloxane with a Pd / C catalyst.

On the other hand, the compound of the above formula (2) can be similarly obtained by a known method, for example, 1,1,1,3.
5,5,5-heptamethyltrisiloxane, 3- (trimethylsiloxy) -1,1,1,5,5,5-hexamethyltrisiloxane, 1,1,1,5,5,5-hexamethyl-3 -Vinyltrisiloxane, 1,1,1,5
It can be obtained by a method of hydrolyzing 5,5-hexamethyl-3-trifluoropropyltrisiloxane or the like with a Pd / C catalyst.

The compounds of the above formula (1) or (2) may be used alone or in combination of two or more,
The blending amount is based on the silica filler of the component (b).
It is desirable to add 1 to 30% by weight, more preferably 2 to 20% by weight. If the amount is less than 1% by weight, the activity of the silica is so strong that the viscosity stability during storage may not be sufficiently improved, and if it exceeds 30% by weight, the mechanical properties of the cured product may be adversely affected. High cost.

The organohydrogenpolysiloxane of the component (e) of the present invention acts as a crosslinking agent for the silicone rubber composition of the present invention. That is, this (e)
The silicon atom-bonded hydrogen atom of the component undergoes an addition reaction with the silicon atom-bonded alkenyl group of the component (a) in the presence of the platinum catalyst of the following component (f) to crosslink, thereby curing the silicone rubber composition. It is a thing. Therefore, the organohydrogenpolysiloxane of the component (e) of the present invention is at least 2 or more per molecule, usually 2 to 200.
It is necessary to have 1, preferably 3 to 50 silicon-bonded hydrogen atoms (ie SiH groups).

This organohydrogenpolysiloxa
The following general composition formula (4) R ’_bH_cSiO_{(4-bc) / 2} Those represented by (4) are preferably used.

Here, R'has 1 to 12 carbon atoms, especially 1 to
Examples of the non-substituted or substituted monovalent hydrocarbon group of 8 and the same groups as those exemplified for R above, preferably those containing no aliphatic unsaturated bond, particularly an alkyl group, an aryl group and an aralkyl group. A group and a substituted alkyl group are preferred. b is 0.8 ≦ b ≦ 2.2, more preferably 1.2 ≦ b ≦ 2, c is 0.002 ≦ c ≦ 1.0,
More preferably, it is a positive number of 0.01 ≦ c ≦ 0.8, and b
+ C is 0.8 <b + c ≦ 3, more preferably 1.5 ≦ b
It is preferable that + c ≦ 2.7, and the molecular structure of the component (e) may be linear, cyclic, branched, or three-dimensional network, and the SiH group is a terminal of the molecular chain. Or may be present in the middle of the molecular chain. further,
The molecular weight of component (e) is not particularly limited, but the viscosity at 25 ° C. is preferably in the range of 1 to 1000 centipoise, and particularly 3 to 500 centipoise.

The amount of the organohydrogenpolysiloxane as the component (e) is determined by the number of silicon atom-bonded hydrogen atoms (that is, SiH groups) in the component (e) and the silicon atom bond in the component (a). The ratio with the number of alkenyl groups is 0.
The amount is preferably 5: 1 to 20: 1, more preferably 1: 1 to 3: 1. If the ratio of silicon atom-bonded hydrogen atoms to the alkenyl group is too low, the composition may not be sufficiently cured, and if it is too high, foaming may occur.

The platinum-based catalyst of the component (f) of the present invention is a catalyst for curing the composition of the present invention. Examples of such platinum-based catalysts include fine powder metal platinum catalysts (for example, those described in US Pat. No. 2,970,150),
Chloroplatinic acid catalysts (for example, those described in US Pat. No. 2,823,218), platinum-hydrocarbon complex compounds (for example, US Pat. No. 3,159,601 or 3,159,662).
), Chloroplatinic acid-olefin compounds (e.g., those described in U.S. Pat. No. 3,516,946), platinum-vinyl siloxane complexes (e.g., U.S. Pat. No. 3,775,452 or U.S. Pat. No. 3,814,780). Those that have been done) and the like. The amount of the component (f) added is preferably 0.1 to 1000 ppm as platinum metal, more preferably 1 to 100 ppm, based on the total amount of the components (a) and (e). is there. If it is less than 0.1 ppm, curing of the composition often does not proceed sufficiently, and if it exceeds 1000 ppm, the cost becomes high.

The silicone rubber composition of the present invention is a liquid composition having fluidity, and its viscosity is not particularly limited, but the viscosity at 25 ° C. is 50 to 50,000 poise, preferably 200 to 20,000 poise. Is desirable. Further, the silicone rubber composition of the present invention,
As long as the effects of the present invention are not impaired, various additives, such as a reaction control agent, a pigment, a flame retardant, and a release agent, which are usually added to this type of composition, are added as optional components. You can

The silicone rubber composition of the present invention can be obtained only by appropriately mixing the above-mentioned components (a) to (f) and optional components, but the production method of the present invention is performed by the organopolysiloxane of the above-mentioned component (a). When a part or all of the above and the whole silica filler of the component (b) are mixed, the condensation catalyst of the component (c) and the specific silanol group-containing organosiloxane compound of the component (d) are blended. Is. That is,
The condensation catalyst of the component (c) accelerates the condensation between the silanol groups of the silica filler of the component (b) and the silanol groups of the component (d), and a large amount of the component (b) can be obtained without impairing the fluidity of the composition. It becomes easy to mix the silica filler, and the activity of the silica filler of the component (b) is suppressed by the condensation of the silanol group of the silica filler of the component (b) and the silanol group of the component (d). Thus, the viscosity stability during storage is improved. In addition, the components (e) and (f) are part or all of the component (a) and (b), (e),
It is preferable that after the component (d) is mixed, it is added and blended.
When mixed with the component (d), the remaining amount of the component (a) can be mixed with the components (e) and (f). Here, the amount of the component (a) mixed with the components (b), (c), and (d) is appropriately selected, but it is 50% by weight of the total amount of the component (a).
More preferably, it is particularly preferably 70% by weight or more. Other optional components can be appropriately selected and blended at the time of adding and blending the components (c) and (d), or at the time of adding the components (e) and (f).

As described above, when the silicone rubber composition of the present invention is produced, it can be obtained simply by uniformly mixing the components (a) to (f) and the optional components at room temperature. As described above, the components (a) to (d) and, if necessary, optional components are kneaded by a kneading machine such as a planetary mixer, a (pressurizing) kneader mixer, or an extruder, and at 100 to 400 ° C. for 1 minute to It is preferable to heat-treat for 8 hours, and then to produce by mixing the above-mentioned components (e) and (f) and, if necessary, optional components.

The silicone rubber composition of the present invention obtained as described above can be injection-molded, transfer-molded, depending on its viscosity, like conventional silicone rubber compositions.
It is possible to mold by appropriately selecting means such as injection molding and compression molding, but in the case of the composition of the present invention, it is more preferable to mold using an injection molding machine. When the composition of the present invention is molded by using such an apparatus, it can be usually cured by heating at room temperature to 250 ° C. for 10 seconds to 120 minutes. The cured product thus obtained may be subjected to secondary vulcanization for 30 minutes to 4 hours, if necessary.

[0037]

The liquid silicone rubber composition of the present invention, particularly (c) when a part or all of the organopolysiloxane of the component (a) and the silica filler of the component (b) are mixed,
The liquid silicone rubber composition obtained by blending the condensation catalyst of the component and the specific silanol group-containing organosiloxane compound of the component (d) has excellent fluidity and curability, and also has a stable viscosity during storage. Therefore, it is particularly suitable as a molding material by an injection molding machine, for example, a molding material for roll members, connector materials for automobile members, microwave ovens, packing such as electronic jars, keyboard members, clock parts, camera parts, and various O-rings. It is preferably used as a material for products.

[0038]

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 addition, the middle part of an Example represents a weight part.

Example 1 Viscosity at 25 ° C. is 100
100 parts of dimethylpolysiloxane (A) having both ends of 00 centipoise blocked with dimethylvinylsiloxy groups was precipitated silica (manufactured by Nippon Silica Industry Co., Ltd., trade name Nipsyl L
P: BET specific surface area 200 m ² / g) 40 parts,
3 parts of the compound (B) represented by the following formula (5) and 2 parts of aqueous ammonia (29%) were put into a kneader mixer, uniformly mixed, and further heated and mixed at 150 ° C. for 1 hour to obtain a liquid silicone rubber base. It was

To 100 parts of this liquid silicone rubber base, 30 parts of the above dimethylpolysiloxane (A) and a viscosity at 25 ° C. represented by the following formula (6) as a cross-linking agent are 1
5 parts of methyl hydrogen polysiloxane of 5 cs, 0.1 part of 1% isopropyl alcohol solution of chloroplatinic acid,
Ethinyl cyclohexanol as a reaction control agent 0.05
Parts were added and uniformly mixed to obtain a liquid silicone rubber composition.

[0041]

[Chemical 6]

Example 2 Instead of the compound (B) in Example 1, a compound (C) represented by the following formula (7)
A liquid silicone rubber composition was obtained in the same manner as in Example 1 except that 3 parts of was used.

[0043]

[Chemical 7]

Comparative Example 1 Similar to Example 1 except that 3 parts of hexamethyldisilazane was used in place of the compound (B) in Example 1 and 1 part of water was used instead of 2 parts of aqueous ammonia (29%). Thus, a liquid silicone rubber composition was obtained.

Comparative Examples 2 and 3 Instead of 3 parts of the compound (B) and 2 parts of ammonia water (29%) in Example 1, dimethylpolysiloxane-α, ω having an average degree of polymerization of 10 was used.
Using 4 parts or 8 parts of diol and using aqueous ammonia (29
%) A liquid silicone rubber composition was obtained in the same manner as in Example 1 except that 2 parts were excluded, but in the case of Comparative Example 2 using 4 parts of dimethylpolysiloxane-α, ω-diol, in the process of production. It has been difficult to compound precipitated silica into a liquid silicone rubber base. Further, in the case of Comparative Example 3 using 8 parts of dimethylpolysiloxane-α, ω-diol, the obtained liquid silicone rubber composition had thixotropic properties and was unsuitable for injection molding.

Comparative Example 4 A liquid silicone rubber composition was obtained in the same manner as in Example 1 except that 2 parts of aqueous ammonia (29%) was excluded.

The curability of the silicone rubber compositions of the above Examples and Comparative Examples at 150 ° C. was measured using a rheometer. In addition, each silicone rubber composition is
A rubber sheet having a thickness of 2 mm was obtained by press molding at 10 ° C. for 10 minutes, and the general physical properties of these were measured. Furthermore,
For each silicone rubber base, the change in viscosity during storage at 60 ° C. was observed. Table 1 shows the results. In addition, Table 1
In T10 and T90, when the torque after 2 minutes from the start of curing is 100%, the torque is 10%,
It is time to reach 90%.

[0048]

[Table 1]

From the results shown in Table 1, it is recognized that the silicone rubber composition of the present invention has a low initial viscosity, excellent curability and fluidity, and a small change in viscosity during storage. On the other hand, using hexamethyldisilazane as a wetter,
The composition in which water was used instead of the condensation catalyst (Comparative Example 1) had a slightly poor curability and had a large change in viscosity during storage. On the other hand, the composition that uses α, ω-siloxane diol as a wetter and does not use a condensation catalyst (Comparative Example 3) has a high initial viscosity, is inferior in fluidity, and has a large change in viscosity during storage. Further, it is recognized that the composition (Comparative Example 4) which does not use a condensation catalyst is inferior in fluidity and has a small effect of improving the viscosity stability during storage.

Example 3 In Example 1, instead of the precipitated silica (Nipsil LP), fumed silica having a specific surface area by the BET method of 200 m ² / g (product name Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) was used. A liquid silicone rubber composition was obtained in the same manner as in Example 1 except that the compound (B) was changed to 6 parts.

Example 4 Except that the fumed silica (Erosil 200) was used in place of the precipitated silica (Nipsil LP) in Example 1 and 6 parts of the compound (C) was used in place of 3 parts of the compound (B). A liquid silicone rubber composition was obtained in the same manner as in Example 1.

Comparative Example 5 In Comparative Example 1, the fumed silica (Erosil 200) was used in place of the precipitated silica (Nipsil LP), and hexamethyldisilazane was added to 8
A liquid silicone rubber composition was obtained in the same manner as in Comparative Example 1 except that 1 part and 2 parts of water were used.

Comparative Example 6 A liquid silicone rubber composition was obtained in the same manner as in Example 3 except that 2 parts of aqueous ammonia (29%) was omitted.

Curability and general physical properties of the rubber sheet obtained from each silicone rubber composition were measured in the same manner as in the above Examples and Comparative Examples, and the change in viscosity during storage at 60 ° C. was observed. . Table 2 shows the results.

[0055]

[Table 2]

According to the results of Table 2, the silicone rubber composition of the present invention has a low initial viscosity, excellent curability and fluidity, and a small change in viscosity during storage, as in the case of Table 1 above. Is recognized. On the other hand, the composition in which hexamethyldisilazane was used as the wetter and water was used instead of the condensation catalyst (Comparative Example 5) had a slightly poor curability and the viscosity change during storage was very large, and no condensation catalyst was used. It can be seen that the composition (Comparative Example 6) has poor fluidity and the effect of viscosity stability during storage is small.

Claims (2)

[Claims] 1. (a) An organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule, (b) a reinforcing silica filler having a specific surface area (BET method) of 50 m ² / g or more, (C) a condensation catalyst, (d) a compound represented by the following general formula (1) or (2), (However, in the formula, R ¹ is a methyl group, a trimethylsiloxy group,
A vinyl group or a trifluoropropyl group is shown. ) (E)
A liquid silicone rubber composition comprising an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule, and (f) a platinum-based catalyst. 2. (a) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule, (b) a reinforcing silica filler having a specific surface area (BET method) of 50 m ² / g or more, (C) a condensation catalyst, (d) a compound represented by the following general formula (1) or (2), (However, in the formula, R ¹ is a methyl group, a trimethylsiloxy group,
A vinyl group or a trifluoropropyl group is shown. ) (E) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule,
(F) In producing a liquid silicone rubber composition containing a platinum-based catalyst, when a part or all of the above component (a) and all of the component (b) are mixed, the above (c) component and (d) are mixed. ) Component is compounded, The manufacturing method of the liquid silicone rubber composition characterized by the above-mentioned.