JP3297976B2 - Liquid silicone rubber composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is not only excellent in fluidity and curing properties, but also has good viscosity stability during storage, and is particularly suitable for liquid injection molding using an injection molding machine. The present invention relates to a silicone rubber composition and a method for producing the same.

[0002]

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

Heretofore, 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 Patent No. 3799)
962).

Further, RO [(CH ₃ ) ₂ SiO] _y H
Α-Alkoxy-ω-siloxanols (R: short-chain alkyl group, y = 3 to 5) are also known, and antisulfones using a mixture of hexamethyltrisiloxanediol and methoxyhexamethyltrisiloxanol are also known. A lacturing agent has also been proposed (US Pat. No. 3,925,285). However, when a silicone oil having a hydroxyl group at a terminal is used as a wetter as described above, it is possible to incorporate a large amount of a silica filler into a silicone polymer, but the obtained silicone polymer composition has thixotropic properties. The composition has a high viscosity and is not suitable for injection molding due to lack of fluidity when molding this composition.

[0005] Apart from the above silicone oils, hexamethyldisilazane is also known as a wetter for liquid silicone rubber compositions. However, the liquid silicone rubber composition obtained by using hexamethyldisilazane as a wetter has good flowability and low viscosity, but due to amine by-produced when compounding hexamethyldisilazane, There were problems such as poor curability and increased viscosity during storage.

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

[0007]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and have found that (a) two or more alkenyl groups bonded to silicon atoms in one molecule. (B) an organopolysiloxane having
A reinforcing silica filler having a specific surface area (BET method) of at least 50 m ² / g, (e) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom 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 the siloxane and the silica filler are added to an addition reaction-curable liquid silicone rubber composition mainly containing a base catalyst. Blending a condensation catalyst (c) for condensing with a silanol group 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), Catalyst (c) and the above siloxane (d)
It has been found that it is effective to add and mix.

[0008]

Embedded image (Where R ¹ is a methyl group, a trimethylsiloxy group,
Indicates a vinyl group or a trifluoropropyl group. )

That is, a specific silanol group-containing siloxane compound represented by the above formula (1) or (2) of the component (d) is added to the organopolysiloxane of the component (a) and the silica filler of the component (b). By blending the condensation catalyst of the component (c) with the surface silanol group of the silica filler and the formula (1) or (2)
By condensing with a silanol group of the compound of, the conventionally obtained silicone oil having a hydroxyl group at the terminal, which had been generated when used as a wetter, thixotropic properties are expressed in the obtained composition, and the viscosity increases. The composition is not suitable for injection molding due to lack of fluidity, and when hexadimethyldisilazane is used instead of the conventional silicone oil, the resulting composition has good fluidity. However, the curing characteristics are deteriorated, the storage stability of the viscosity is also reduced, all of the problems that are solved, the curing characteristics are significantly improved without impairing the good fluidity of the liquid silicone rubber composition, In addition, the increase in viscosity of the silicone rubber composition during storage is suppressed, and the siloxane compound of the above formula (1) or (2) has a high activity of silanol groups. , 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.

Accordingly, the present invention relates to (a) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule; 100 parts by weight; (b) a specific surface area (BET method) of 50 m ² / g. 5 to 100 parts by weight of the above reinforcing silica filler; (c) at least one condensation catalyst selected from a basic compound, a tin compound, a titanium compound, and a zinc compound;
(D) 0.005 to 1 part by weight per 1 part by weight of the component; (d) a compound represented by the following general formula (1) or (2);
(E) an organohydrogenpolysiloxane having 2 or more hydrogen atoms bonded to silicon atoms in one molecule;
The ratio of the number of silicon-bonded hydrogen atoms in component (e) to the number of silicon-bonded alkenyl groups in component (a) is 0.
(F) a platinum-based catalyst; a liquid silicone rubber containing 0.1 to 1000 ppm of platinum metal with respect to the total amount of the component (a) and the component (e). In producing the composition and the silicone rubber composition, the components (c) and (d) are compounded when a part or all of the component (a) and the entire component (b) are mixed. The present invention provides a method for producing a liquid silicone rubber composition, characterized in that:

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

The organopolysiloxane of the component (a)
The following average composition formula (3) R _aSiO_{(4-a) / 2} .. (3) are preferably used.

Here, R Is the number of carbon atoms bonded to the silicon atom
1-12, especially 1-8 unsubstituted or substituted monovalent hydrocarbon groups
For example, methyl, ethyl, propyl, isopropyl
Butyl, pentyl, neopentyl, hexyl, hept
Alkyls such as tyl, octyl, nonyl, decyl, dodecyl
Group, cyclopentyl, cyclohexyl, cyclohepti
Cycloalkyl groups such as vinyl, allyl, propeni
, Isopropenyl, butenyl, isobutenyl, hexyl
Alkenyl groups such as cyclohexyl, phenyl, tri
Aryl groups such as phenyl, xylyl, naphthyl and biphenyl;
Benzyl, phenylethyl, phenylpropyl, methyl
Aralkyl groups such as benzyl and water in these hydrocarbon groups
Halogen atoms such as F, Cl, Br, etc.
A chloromethyl group substituted with a substituent or a cyano group,
Lomoethyl group, 3,3,3-trifluoropropyl group,
3-chloropropyl group, cyanoethyl group and the like.
You.

In this case, in the organopolysiloxane, at least two of the organic groups represented by R are alkenyl groups, preferably 0.001 to 5 in all R groups.
Mole%, more preferably 0.01 to 2 mol% are alkenyl groups. If the proportion of the alkenyl group is too small, the curability of the resulting composition will be reduced, and if it is too large, physical properties such as tensile strength, tear strength and elongation of the cured product will be reduced. The alkenyl group may be bonded to a silicon atom at the terminal of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be present at 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. The molecular structure of this organopolysiloxane is preferably basically linear, and has alkenyl groups at both ends of the molecular chain. It is preferable that it has a branched structure. The organopolysiloxane is preferably one whose molecular chain end is blocked with a triorganosilyl group such as trivinylsilyl, methyldivinylsilyl, dimethylvinylsilyl or trimethylsilyl.

The molecular weight of the above-mentioned organopolysiloxane is appropriately selected, but the viscosity at 25 ° C. is from 100 to 300,000 centipoise in view of curing into a rubber-like elastic material and providing a liquid silicone rubber composition. And 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 whose (method) is 50 m ² / g or more include fumed silica, calcined silica, precipitated silica, and the like. These may be used alone or in combination of two or more. . These silica fillers may be those whose surfaces are 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 comprises 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 /
g of fumed silica is preferred. In addition, in terms of physical properties such as cost and elasticity of the obtained silicone rubber composition, reinforcing silica having a specific surface area of 50 to 800 m ² / g is particularly preferable.

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

In the present invention, when the organopolysiloxane of the component (a) and the silica filler of the component (b) are blended, the condensation catalyst of the component (c) and the compound (wetter) of the following component (d) are used. And (c)
The addition of the component condensation catalyst significantly 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 between the silanol group on the silica surface 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 as shown below, basic compounds such as potassium-siliconate salts as shown below, tin octylate, tin compounds such as dibutyltin dilaurate, tetrabutyl titanate and the like Titanium compounds, zinc compounds such as zinc octylate, zinc naphthylate and the like are used, and among them, ammonia, aqueous ammonia and the like are particularly preferably used.

[0021]

Embedded image

The amount of the condensation catalyst of component (c) is 0.005 to 1 part by weight per 1 part by weight of component (d) below.
Preferably it is 0.01 to 0.8 parts by weight. If the amount is too small, the resulting composition may not have sufficient fluidity.If the 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). When mixing the components (a) and (b), a wetter is used. Is added together with the condensation catalyst of the above component (c), whereby the curability, fluidity and viscosity during storage of the silicone rubber composition of the present invention are remarkably improved.

[0024]

Embedded image (Where R ¹ is a methyl group, a trimethylsiloxy group,
Indicates a vinyl group or a trifluoropropyl group. )

Here, the compound represented by the above formula (1) can be obtained by a known method.
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 hydrolysis of vinyltetrasiloxane or the like with a Pd / C catalyst.

On the other hand, the compound of the above formula (2) can also be obtained by a known method, for example, 1,1,1,3,3.
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 such as hydrolysis of 5,5-hexamethyl-3-trifluoropropyltrisiloxane 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 compounding amount is based on the silica filler (b).
It is desirable to add 1 to 30% by weight, but more preferably 2 to 20% by weight. If it 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. If it exceeds 30% by weight, the mechanical properties of the cured product may be adversely affected, Increases cost.

The organohydrogenpolysiloxane of the component (e) of the present invention functions as a crosslinking agent for the silicone rubber composition of the present invention. That is, this (e)
The silicon-bonded hydrogen atom of the component is subjected to an addition reaction with the silicon-bonded alkenyl group of the above-mentioned component (a) in the presence of a platinum-based catalyst of the following component (f), whereby the silicone rubber composition is cured by crosslinking. Things. Therefore, the organohydrogenpolysiloxane of the component (e) of the present invention contains at least two or more, usually 2 to 200, molecules per molecule.
, Preferably 3 to 50 silicon-bonded hydrogen atoms (i.e. SiH groups).

This organohydrogenpolysiloxane is
The following general composition formula (4): ’_bH_cSiO_{(4-bc) / 2} .. (4) are preferably used.

Here, R 'has 1 to 12 carbon atoms, especially 1 to 12 carbon atoms.
8 unsubstituted or substituted monovalent hydrocarbon groups, and include the same groups as those exemplified above for R, preferably those containing no aliphatic unsaturated bond, and particularly include alkyl groups, aryl groups, and aralkyl groups. And substituted alkyl groups are preferred. b is 0.8 ≦ b ≦ 2.2, more preferably 1.2 ≦ b ≦ 2, c is 0.002 ≦ c ≦ 1.0,
More preferably a positive number of 0.01 ≦ c ≦ 0.8, b
+ C is 0.8 <b + c ≦ 3, more preferably 1.5 ≦ b
+ C ≦ 2.7 is preferred, and the molecular structure of the component (e) may be any of linear, cyclic, branched, and three-dimensional network, and the SiH group is a terminal of the molecular chain. Or in the middle of the molecular chain. further,
Although there is no particular limitation on the molecular weight of the component (e), the viscosity at 25 ° C. is preferably in the range of 1 to 1000 centipoise, particularly preferably in the range of 3 to 500 centipoise.

The amount of the organohydrogenpolysiloxane of the component (e) is determined by the number of silicon-bonded hydrogen atoms (ie, SiH groups) in the component (e) and the number of silicon-bonded hydrogen atoms in the component (a). The ratio to the number of alkenyl groups is 0.
The amount is preferably from 5: 1 to 20: 1, more preferably from 1: 1 to 3: 1. If the ratio of silicon-bonded hydrogen atoms to alkenyl groups 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. Such platinum-based catalysts include, for example, fine powdered metal platinum catalysts (for example, those described in US Pat. No. 2,970,150),
Chloroplatinic acid catalysts (for example, those described in U.S. Pat. No. 2,823,218) and platinum-hydrocarbon complex compounds (for example, U.S. Pat. Nos. 3,159,601 and 3,159,662)
JP-A No. 3516946, chloroplatinic acid-olefin compounds (for example, those described in US Pat. No. 3,516,946), and platinum-vinylsiloxane complexes (for example, those described in US Pat. No. 3,775,452 or 3,814,780). ). The added amount of the component (f) is preferably 0.1 to 1000 ppm as platinum metal with respect to the total amount of the components (a) and (e), more preferably 1 to 100 ppm. is there. If the amount is less than 0.1 ppm, the curing of the composition often does not proceed sufficiently, and if it exceeds 1000 ppm, the cost increases.

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. should be 50 to 50,000 poise, preferably 200 to 20,000 poise. Is desirable. Further, the silicone rubber composition of the present invention includes:
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 mold release agent, which are usually added to the composition of this type, if necessary, may be added as optional components. Can be.

The silicone rubber composition of the present invention can be obtained by simply mixing the above-mentioned components (a) to (f) and optional components, but the production method of the present invention provides the above-mentioned organopolysiloxane of the above-mentioned component (a). When mixing part or all of the above and the entirety of the silica filler of the component (b), the condensation catalyst of the component (c) and the specific silanol group-containing organosiloxane compound of the component (d) are blended. It is. That is,
The condensation of the silanol group of the silica filler of the component (b) with the silanol group of the component (d) is promoted by the condensation catalyst of the component (c), and a large amount of the component (b) can be produced without impairing the fluidity of the composition. It becomes easy to mix the silica filler, and the condensation of the silanol group of the silica filler of the component (b) with the silanol group of the component (d) suppresses the activity of the silica filler of the component (b). Thus, the viscosity stability during storage is improved. Note that the components (e) and (f) are part or all of the component (a) and the components (b), (e),
After mixing the component (d), it is preferable to add and mix the components. At this time, part of the component (a) is partially added to the components (b), (c),
When mixed with the component (d), the remaining amount of the component (a) can be mixed with these components (e) and (f). Here, the amount of the component (a) to be mixed with the components (b), (c), and (d) is appropriately selected, but is 50% by weight of the entire component (a).
It is preferably at least 70% by weight. Other optional components can be appropriately selected and added at the time of adding and compounding 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 is possible to obtain the silicone rubber composition simply by mixing the above-mentioned components (a) to (f) and optional components uniformly at room temperature. As described above, the above components (a) to (d) and optional components are kneaded with a kneading machine such as a planetary mixer, a (pressurized) kneader mixer, or an extruder at 100 to 400 ° C. for 1 minute to It is preferable to heat-treat for 8 hours, and then mix the above-mentioned components (e) and (f) and optional components as needed to produce the composition.

The silicone rubber composition of the present invention obtained as described above can be subjected to injection molding, transfer molding,
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 preferred to mold using an injection molding machine. When the composition of the present invention is molded 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 an additional 30 minutes to 4 hours, if necessary.

[0037]

When the liquid silicone rubber composition of the present invention, in particular, part or all of the organopolysiloxane of the component (a) and the silica filler of the component (b) are mixed, (c)
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 for an injection molding machine. For example, molding of a roll member, a connector material of an automobile member, a packing of a microwave oven, an electronic jar, a keyboard member, a watch part, a camera part, various O-rings, and the like. It is suitably used as a material for articles.

[0038]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The middle part in the examples represents parts by weight.

Example 1 The viscosity at 25 ° C. was 100
Precipitated silica (manufactured by Nippon Silica Kogyo Co., Ltd., trade name: Nipsil L)
P: specific surface area by BET method 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%) are placed in a kneader mixer, mixed uniformly, and further heated and mixed at 150 ° C. for 1 hour to obtain a liquid silicone rubber base. Was.

In 100 parts of this liquid silicone rubber base, 30 parts of the dimethylpolysiloxane (A) were used, and as a crosslinking agent, the viscosity at 25 ° C. represented by the following formula (6) was 1
2 parts of 5 cs methyl hydrogen polysiloxane, 0.1 part of a 1% solution of chloroplatinic acid in isopropyl alcohol,
Ethynylcyclohexanol 0.05 as a reaction control agent
Was added and uniformly mixed to obtain a liquid silicone rubber composition.

[0041]

Embedded image

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

[0043]

Embedded image

Comparative Example 1 Same as Example 1 except that compound (B) was replaced by 3 parts of hexamethyldisilazane and 1 part of water was replaced by 2 parts of aqueous ammonia (29%). Thus, a liquid silicone rubber composition was obtained.

Comparative Examples 2 and 3 In Example 1, dimethylpolysiloxane-α, ω having an average polymerization degree of 10 was used instead of 3 parts of the compound (B) and 2 parts of aqueous ammonia (29%).
Using 4 parts or 8 parts of diol, and adding ammonia water (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, It was difficult to incorporate precipitated silica into the liquid silicone rubber base. 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 not suitable 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 omitted.

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 was used for 120
Press molding was performed at 10 ° C. for 10 minutes to obtain rubber sheets each having a thickness of 2 mm, and their general physical properties were measured. Furthermore,
The viscosity change of each silicone rubber base during storage at 60 ° C. was observed. Table 1 shows the results. Table 1
In T10 and T90, the torque was 10% when the torque at the lapse of 2 minutes after the start of curing was 100%,
It is time until it becomes 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 using water instead of the condensation catalyst (Comparative Example 1) has a slightly poor curability and a large change in viscosity during storage. On the other hand, the composition using α, ω-siloxanediol as a wetter and not using 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 without the condensation catalyst (Comparative Example 4) is inferior in fluidity and has a small effect of improving viscosity stability during storage.

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

Example 4 The procedure of Example 1 was repeated except that the precipitated silica (Nipsil LP) was replaced by the fumed silica (Erosil 200) and the compound (B) was replaced by 6 parts of the compound (C). A liquid silicone rubber composition was obtained in the same manner as in Example 1.

Comparative Example 5 The same procedure as in Comparative Example 1 was carried out except that the above-mentioned fumed silica (Erosil 200) was used instead of the precipitated silica (Nipsil LP), and hexamethyldisilazane was used in 8 parts.
Liquid silicone rubber composition was obtained in the same manner as in Comparative Example 1 except that the amount of water and the amount of water were changed to 2 parts.

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.

The curability and general physical properties of the rubber sheets obtained from the respective silicone rubber compositions were measured in the same manner as described above for these 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 shown in 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 Table 1 above. Is recognized. On the other hand, the composition using hexamethyldisilazane as a wetter and using water instead of the condensation catalyst (Comparative Example 5) has a slightly poor curability, a very large change in viscosity during storage, and does not use a condensation catalyst. It is recognized that the composition (Comparative Example 6) has poor fluidity, and the effect of viscosity stability during storage is small.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-227882 (JP, A) JP-A-8-157726 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/07 C08L 83/05 C08K 3/36 C08K 5/541

Claims (2)

(57) [Claims] 1. (a) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule; 100 parts by weight; (b) a reinforcing property having a specific surface area (BET method) of 50 m ² / g or more. Silica filler; 5 to 100 parts by weight; (c) a condensation catalyst selected from a basic compound, a tin compound, a titanium compound, or a zinc compound; 0.005 to 1 part by weight per 1 part by weight of component (d); (D) a compound represented by the following general formula (1) or (2);
1 to 30% by weight based on the component (b) (Where R ¹ is a methyl group, a trimethylsiloxy group,
Indicates a vinyl group or a trifluoropropyl group. (E) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule;
The ratio of the number of silicon-bonded hydrogen atoms in component (e) to the number of silicon-bonded alkenyl groups in component (a) is 0.
(F) a platinum-based catalyst; characterized by containing 0.1 to 1000 ppm of platinum metal based on the total amount of the component (a) and the component (e). Liquid silicone rubber composition. 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 selected from a basic compound, a tin compound, a titanium compound, and a zinc compound; (d) a compound represented by the following general formula (1) or (2); (Where R ¹ is a methyl group, a trimethylsiloxy group,
Indicates a vinyl group or a trifluoropropyl group. In preparing a liquid silicone rubber composition containing (e) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, and (f) a platinum-based catalyst, the component (a) is used. A method for producing a liquid silicone rubber composition, comprising mixing the above components (c) and (d) when a part or all of the above and all the components (b) are mixed.