JPH0770444A - Composition for solvent resistant silicone gel - Google Patents

Abstract

PURPOSE:To obtain the composition which can form a silicone gel having a high solvent resistance to a gasoline, etc., and without impairing the flexibility at low temperatures. CONSTITUTION:A composition for a solvent resistant silicone gel consists of (A) 100 wt.pt. of a vinyl group containing branched organo polysiloxane containing 70.0-98.5mol% of (CF3-CH2-CH2)(CH3)SiO unit, 0.5-10.0mol% of RSiO1.5, unit and 1.0-10.0mol% of (CH2 = CH) (CH3)2SiO0.5 [wherein, R is a radical selected from a group consisting of 3,3,3-trifluoropropyl, phenyl, methyl and vinyl radicals], (B) 0.1-30 wt.pt. of an organohydrogen polysiloxane which has at least one hydrogen atom bonded to the silicon atom per molecule, and (C) a catalyst for addition reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent-resistant silicone gel composition, and more particularly to a silicone gel composition which does not lose its flexibility even at low temperatures.

[0002]

2. Description of the Related Art Silicone gel has excellent electrical insulation properties, stabilization of electrical properties and flexibility,
It is used for potting and encapsulating electronic parts, especially as a covering material for control circuit elements such as power transistors, ICs and capacitors, and protects these from thermal and mechanical damage. However, in order to sufficiently cope with the recent electronicization of automobiles, the above properties are not sufficient, and the silicone gel has solvent resistance to hydrocarbon fluids and gasoline, and does not lose flexibility even at low temperatures. Is desired to be developed.

[0003]

A linear organopolysiloxane having a 3,3,3-trifluoropropyl group has been conventionally recommended as a component of a solvent resistant silicone gel composition. In order to improve the solvent resistance to hydrocarbon fluids and gasoline, it is necessary to increase the content ratio of 3,3,3-trifluoropropyl group in the linear organopolysiloxane. However,
When the content ratio of the 3,3,3-trifluoropropyl group is increased, there is a problem that flexibility at low temperature is deteriorated. Therefore, an object of the present invention is to provide a composition for silicone gel which has excellent solvent resistance to gasoline and the like and which does not lose its flexibility even at low temperatures.

[0004]

[Here, R is a group selected from the group consisting of a 3,3,3-trifluoropropyl group, a phenyl group, a methyl group and a vinyl group. ]

100 parts by weight of a branched organopolysiloxane containing (B) 0.1 to 30 parts by weight of an organohydrogenpolysiloxane containing at least one hydrogen atom bonded to a silicon atom in one molecule, and (C) addition Provided is a solvent-resistant silicone gel composition containing a reaction catalyst.

In the present invention, silicone gel means AS
The penetration measured by the method specified in TM D 1403 using a 1/4 scale cone is in the range of 0 to 200, preferably 10
It means a silicone cured product in the range of 120 to 120, particularly preferably in the range of 20 to 100.

(A) Branched organopolysiloxane containing vinyl group
Xan In the present invention, the vinyl group-containing branched organopolysiloxane of the component (A) used as the base component is, as described above, (CF ₃ -CH ₂ -CH ₂ ) (CH ₃ ) SiO unit 70.0 to 98.5 mol%, RSiO _1.5 unit 0.5 to 10.0 mol%, and (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit 1.0 to 10.0 mol% [where R is a 3,3,3-trifluoropropyl group , A phenyl group, a methyl group and a vinyl group. ] Is contained. The organopolysiloxane may contain, for example, (CH ₃ ) ₃ SiO _0.5 unit in an amount of 10.0 mol% or less.

(CF ₃ --CH ₂ --CH ₂ ) (CH ₃ ) SiO units are
70.0 to 98.5 mol in the branched organopolysiloxane
%, Preferably 75 to 95 mol%. Also, (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit is 1.0 to 10.
It is contained at 0 mol%, preferably 1.0 to 8.0 mol%, and more preferably 3.0 to 7.0 mol%. The RSiO _1.5 unit is a unit necessary for branching the organopolysiloxane, and 0.5 unit in the branched organopolysiloxane.
It is contained in an amount of ˜10.0 mol%, preferably 2.0 to 5.0 mol%. If the content of the RSiO _1.5 unit is less than 0.5 mol%, the flexibility at low temperature decreases, and if it exceeds 10.0 mol%, it becomes difficult to produce a branched organopolysiloxane.

The content of the vinyl group in the organic group bonded to the silicon atom of the branched organopolysiloxane is preferably 0.5 to 8.0 mol%, more preferably 3.0 to 7.0 mol%. . If the content of the vinyl group is too low, the crosslink density is lowered, and thus a cured product cannot be obtained. On the other hand, if the content of the vinyl group is too large, the resulting gel hardened product becomes too hard to function as a gel. This vinyl group is RSiO
It can exist in both _1.5 units and (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 units, but due to ease of synthesis (CH ₂ = CH).
It is preferred that it be present only in (CH ₃ ) ₂ SiO _0.5 units.

The above branched organopolysiloxane can be produced, for example, by the following production method 1 and production method 2. Production Method 1 The branched organopolysiloxane is, for example, a silane cohydrolysis product containing a RSiO _1.5 unit obtained by cohydrolyzing organotrichlorosilane or the like with another chlorosilane, and a vinyl group-containing organodisiloxane. It is produced by ring-opening polymerization of a raw material such as methyl-3,3,3-trifluoropropylsiloxane cyclic trimer in the presence of an equilibration catalyst selected from the group consisting of alkali catalysts and acid catalysts. Examples of the alkali catalyst include hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide, tetraalkylphosphonium hydroxide, tetraalkylammonium hydroxide, and silanolates thereof. Examples of the acid catalyst include sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid and the like.

Production Method 2 The branched organopolysiloxane can also be produced as follows. First, methyl-3,3,3-trifluoropropylsiloxane cyclic trimer was added in the presence of water, organosiloxane, terminal silanol-terminated organopolysiloxane, triorganosilanol, diorganosilanediol, organosilanetriol, etc. A ring-opening polymerization product is produced by carrying out ring-opening polymerization at 50 ° C. or lower, preferably 0 to 20 ° C., using a coordinated silicon catalyst.
Next, by silylating the molecular end of the ring-opening polymerization product in the presence of an acid or an alkali using a vinyl group-containing silylating agent such as vinyldiorganohalogenated silane,
Branched organopolysiloxanes can be produced. The amount of the silylating agent used is appropriately set according to the number of vinyl groups to be introduced into the molecule, but with respect to 100 parts by weight of the organopolysiloxane of the ring-opening polymerization product, usually,
It is in the range of 0.5 to 30 parts by weight, preferably 0.5 to 10 parts by weight.

In this production method 2, when the ring-opening polymerization temperature exceeds 50 ° C., methyl-3,3,3-trifluoropropylsiloxane cyclic tetramer and pentamer (hereinafter referred to as F ₄ and F) are used. ₅ ) is produced as a large amount. These F ₄ and F ₅
Can not be distilled off under reduced pressure. Therefore, the gel-cured product of the composition using the branched organopolysiloxane obtained by the ring-opening polymerization at a temperature of more than 50 ° C. contains a large amount of F ₄ and F ₅ which do not participate in the crosslinking reaction. when placed in an environment, F ₄ and F ₅ are extracted by the solvent. As a result, the flexibility cannot be maintained, the solvent resistance becomes unsatisfactory, and the original properties of the gel are lost.

Among the two production methods exemplified above, the methyl-3,3,3-trifluoropropylsiloxane cyclic trimer of Production Method 1 is obtained by ring-opening polymerization using an equilibration catalyst. The branched organopolysiloxane thus obtained is excellent in solvent resistance itself, but in this method, F ₄ and F
_A large amount of ₅ is by-produced. Therefore, as described above, since the gel cured product of the composition using the branched organopolysiloxane produced by the method of Production method 1 contains a large amount of F ₄ and F _{5 which} are not involved in the crosslinking reaction, When placed in a solvent environment, the flexibility cannot be maintained, the solvent resistance becomes unsatisfactory, and the original properties of the gel are lost. However, a ring-opening polymerization product obtained by ring-opening polymerization of the methyl-3,3,3-trifluoropropylsiloxane cyclic trimer of the production method 2 at 50 ° C. or lower using a pentacoordinated silicon catalyst. In addition, F ₄ and F ₅ are hardly produced as by-products. For example, in the branched organopolysiloxane derived from this ring-opening polymerization product, the content of F ₄ and F ₅ is 6% by weight or less. Therefore, when a branched organopolysiloxane obtained by using such a ring-opening polymerization product is used as a base component, the gel formed therefrom contains almost all solvent-extracting components F ₄ and F _5. Therefore, it is preferable to use the branched organopolysiloxane obtained by the method of the production method 2 because it can maintain flexibility and exhibits good solvent resistance.

As the above-mentioned pentacoordinated silicon catalyst, various ones can be used, and the following are particularly preferable examples in the present invention.

[0014]

[Chemical 1]

In the above formula, M ⁺ is BzMe ₃ N ⁺ , Bu ₄ N
⁺ , Me ₄ N ⁺ , Li ⁺ , Na ⁺ or K ⁺ (wherein Me is a methyl group, Bu is a butyl group, Bz is a benzyl group, and the same applies hereinafter), and R is It is a group selected from the group consisting of 3,3,3-trifluoropropyl group, phenyl group, methyl group and vinyl group. The five-coordinate silicon catalyst is
Generally, it is used in the range of 10 to 1000 ppm based on the total amount of siloxane.

Examples of the branched organopolysiloxane described above include those represented by the following (1) and (2). _{(1) (CF 3 -CH 2} -CH 2) (CH 3) SiO units: 93.5 mol
% (C ₆ H ₅ ) SiO _1.5 unit: 3.0 mol% (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit: a branched organopolysiloxane composed of 3.5 mol%.

(2) (CF ₃ -CH ₂ -CH ₂ ) (CH ₃ ) SiO unit: 89.0 mol% (C ₆ H ₅ ) SiO _1.5 unit: 5.0 mol% (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit: 3.0 mol% (CH ₃ ) ₃ SiO _0.5 unit: 3.0 mol% branched organopolysiloxane.

The viscosity of these branched organopolysiloxanes at 25 ° C. is usually in the range of 50 to 100,000 cP, preferably 300 to 5000 cP.

In the present invention, the above-mentioned branched organopolysiloxane can be used alone or in combination of two or more kinds.

(B) Organohydrogen polysiloxa
The component (B), an organohydrogenpolysiloxane used in the present invention, reacts with the vinyl group in the component (A) to form a gel-cured product, and contains one hydrogen atom bonded to a silicon atom. At least one, preferably 2 to
I have twelve.

The amount of the organohydrogenpolysiloxane blended is such that the hydrogen atom bonded to the silicon atom in the molecule, that is, the SiH group, is based on 1 mol of the vinyl group bonded to the silicon atom in the component (A). The amount is preferably 0.3 to 2.0 mol. If the amount of hydrogen atoms bonded to silicon atoms is too small or too large, the resulting gel cured product tends to have unsatisfactory heat resistance.

Such a hydrogen atom may be bonded to any silicon atom at the molecular end or in the molecular chain. The siloxane skeleton may be linear or branched.
Further, the substituent bonded to the silicon atom in the organohydrogenpolysiloxane of the component (B) is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a cyclohexyl group; For example, aryl groups such as phenyl group, tolyl group, xylyl group, and naphthyl group; for example, aralkyl groups such as benzyl group, phenylethyl group; and halogen-substituted alkyl such as chloromethyl group, 3,3,3-trifluoropropyl group. Examples include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms (excluding aliphatic unsaturated hydrocarbon groups) such as groups, but the compatibility of the (A) component and the (B) component From the viewpoint of the physical properties of the obtained gel cured product, methyl group, phenyl group and 3,3,3-trifluoropropyl group are preferable. Particularly, considering the compatibility with the component (A), the organohydrogenpolysiloxane of the component (B) is preferably a fluorine-containing one,
As the fluorine content of the component (A) increases, the organohydrogenpolysiloxane having a higher fluorine content is used.

The organohydrogenpolysiloxane preferably used in the present invention is [(CH ₃ ) ₃ SiO _0.5 ] ₂ [(CF ₃ CH ₂ CH ₂ ) (CH ₃ ) SiO] ₆
[(CH ₃ ) HSiO] ₄ , [(CH ₃ ) ₃ SiO _0.5 ] [(CF ₃ CH ₂ C
H ₂ ) (CH ₃ ) SiO] ₆ [(CH ₃ ) HSiO] ₃ − [(CH ₃ ) ₂ HSiO
_0.5 ] and the like are exemplified.

The viscosity of these organohydrogenpolysiloxanes at 25 ° C. is preferably in the range of 10 to 10000 cP, more preferably 50 to 1000 cP. In the present invention, these organohydrogenpolysiloxanes may be used alone or in combination of two or more.

(C) Addition Reaction Catalyst The addition reaction catalyst of the component (C) is used to accelerate the curing by the addition reaction between the vinyl group in the component (A) and the SiH group in the component (B) described above. Used and known per se. Examples of such an addition reaction catalyst include chloroplatinic acid, an alcohol-modified solution of chloroplatinic acid, a coordination compound of chloroplatinic acid and an olefin or vinylsiloxane, tetrakis (triphenylphosphine) palladium, chlorotris (triphenyl). Phosphine) rhodium and the like are exemplified, but platinum-based ones are particularly preferable. Such a catalyst is usually added in a proportion of 0.1 to 1000 ppm in terms of metal based on the total amount of the component (A) and the component (B).

Other Compounding Agents In addition to the above-mentioned components (A) to (C), various known compounds can be added to the organopolysiloxane composition of the present invention. For example, fumed silica, silica aerosil, precipitated silica, ground silica, diatomaceous earth, iron oxide, alumina, zinc oxide, titanium oxide,
Mechanical strength and the like can be adjusted by adding an inorganic filler such as calcium carbonate, magnesium carbonate, zinc carbonate or carbon black. Further, hollow inorganic fillers, hollow organic fillers, organosilicone resins, rubbery spherical fillers, etc. can be added. Furthermore, it is also possible to control the curing reaction by adding a reaction control agent such as a polymethylvinylsiloxane cyclic compound, an acetylene compound, an organic phosphorus compound. The amount of these compounding agents used is optional as long as the properties of the resulting cured product are not impaired.

Silicone Gel Composition The silicone gel composition of the present invention is prepared by uniformly mixing the above-mentioned components. This composition, when heated to a temperature of 60 to 200 ° C., for example, forms a gel cured product having excellent flexibility and solvent resistance at low temperatures.

[0028]

In the silicone gel composition, the method of increasing the content of 3,3,3-trifluoropropyl group is generally used to improve the solvent resistance. However, 3,
A gel cured product obtained by curing a composition containing a linear organopolysiloxane having a high content of 3,3-trifluoropropyl groups and having no RSiO _1.5 unit in the molecule is When placed, the crystallization gradually progresses and the original flexibility of the silicone gel is impaired.

The composition of the present invention is characterized by containing a vinyl group in one molecule and containing 0.5 to 10 mol% of a branching unit represented by RSiO _1.5 (where R is as described above). The branched organopolysiloxane contained therein is used as a base component, which makes it possible to form a silicone gel having excellent solvent resistance while maintaining flexibility at low temperatures. The reason for this is that the branching unit RSiO
It is presumed that the introduction of _1.5 units disturbed the regularity of the polysiloxane and prevented the crystallization of the polysiloxane from proceeding.

[0030]

[Examples] In the following Examples and Comparative Examples, "parts" means "parts by weight", and the viscosity is a value measured at 25 ° C. Example 1 Preparation of branched organopolysiloxane (A-1) Three chlorosilanes: 149.6 g (1.0 mol) MeSiCl ₃ (CF ₃ CH ₂ CH ₂ ) (Me) SiCl ₂ 211 1.0 g (10.0 mol) Me _After 54.3 g (0.5 mol) of ₃ SiCl was uniformly mixed, it was added dropwise to 10000 g of water for hydrolysis. Next, the hydrolyzed mixed solution was washed with water 5 times, and then dehydrated with anhydrous sodium sulfate. In this way, the hydrolysis product T was obtained.

Subsequently, the hydrolysis product T obtained above was obtained.
166.8 g and the following two compounds: [(CF ₃ CH ₂ CH ₂ ) (Me) SiO] ₃ 312.0 g [(CH ₂ = CH) (Me) ₂ Si] ₂ O 18.6 g were placed in a 1000 ml flask. After charging, 0.24 g of trifluoromethanesulfonic acid was added as an equilibration catalyst, and the mixture in the flask was stirred at 25 ° C. for 8 hours.

Then, 10 g of sodium hydrogen carbonate was added to the above mixture in the 1000 ml flask, and the mixture was stirred for 3 hours to neutralize the equilibrated catalyst. Next, sodium hydrogen carbonate and the neutralized salt were separated by filtration, and the low boiling point compound was distilled off by heating under reduced pressure. Thus, (CF ₃ CH ₂ CH ₂ ) (Me) SiO unit: 89.6 mol% MeSiO _1.5 unit: 2.99 mol% (CH ₂ = CH) (Me) ₂ SiO _0.5 unit: 5.97 mol% Me ₃ SiO _0.5 A branched organopolysiloxane (A-1) having a unit of 1.49 mol% and a viscosity of 1500 cP was obtained.

Production of Organohydrogenpolysiloxane ( B-1) Also, the following two compounds: [(CF ₃ CH ₂ CH ₂ ) (Me) SiO] ₃ 936.6 g (HMeSiO) ₄ 240.4 g Me ₃ SiO 162.2 g of Me ₃ was charged into a 2000 ml flask, 0.59 g of trifluoromethanesulfonic acid was added as an equilibration catalyst, and the mixture in the flask was stirred at 25 ° C. for 8 hours.

Then, 10 g of sodium hydrogen carbonate was added to the above mixture in the 2000 ml flask and stirred for 3 hours to neutralize the equilibrated catalyst. Next, sodium hydrogen carbonate and the neutralized salt were separated by filtration, and the low boiling point compound was distilled off by heating under reduced pressure. Thus, the following formula:

[Chemical 2] And an organohydrogenpolysiloxane (B-1) having a viscosity of 31 cP was obtained.

Preparation of Composition I for Silicone Gel To 100 parts of the above-mentioned branched organopolysiloxane (A-1), a vinylsiloxane complex of chloroplatinic acid was added, and further 0.1 part of ethynylcyclohexanol was added to obtain a uniform composition. Mixed in. Then, 5.2 parts of hydrogen polysiloxane (B-1) was added to the obtained mixture and mixed uniformly. The vinylsiloxane complex of chloroplatinic acid has a platinum content of 5 with respect to the total amount of the branched organopolysiloxane (A-1) and the organohydrogenpolysiloxane (B-1).
An amount of ppm was added. Thus, the silicone gel composition I was prepared.

Physical Properties Test of Cured Gel The composition I for silicone gel obtained above was subjected to 1
It was heat-cured for a time to obtain a transparent gel-cured product. With respect to this gel cured product, penetration measurement at 25 ° C. and −50 ° C. and gasoline immersion test were conducted by the following methods. The results are shown in Table 1.

Penetration was measured using a 1/4 scale cone according to ASTM D 1403.

Gasoline Immersion Test 10 g of a gasoline swollen gel cured product was immersed in 200 ml of gasoline at 25 ° C. for 70 hours. After the immersion, the surface of the cured product was wiped off with gasoline, and the weight of the cured product was measured to determine the weight increase rate (% by weight) with respect to the gel cured product before immersion.

10 g of a gasoline extracted gel cured product was immersed in 200 ml of gasoline at 25 ° C. for 70 hours. After the immersion, the cured product was air-dried for 72 hours, and then the weight of the cured product was measured to determine the weight reduction rate (% by weight) with respect to the gel cured product before immersion.

Example 2 Preparation of Branched Organopolysiloxane (A-2) 400.0 g of acetonitrile and the following two compounds: [(CF ₃ CH ₂ CH ₂ ) (Me) SiO] ₃ 468.0 g (C ₆ H ₅ ) Si (OH) ₃ 15.61 g and then with stirring at 20 ° C., with the following formula: [(C ₆ H ₅ ) Si (O ₂ C ₆ H ₄ ) ₂ ] ^-・ C ₆ H ₅ CH ₂
0.01 g of a pentacoordinated silicon catalyst represented by (CH ₃ ) ₃ N ⁺ was added and polymerization was carried out for 5 hours.

Next, 30.0 g of vinyldimethylchlorosilane and the following compound: [(CH ₂ = CH) (Me) ₂ Si] -NH- [Si (Me) ₂ (CH ₂ = CH)]
40.0 g was added to carry out silylation of the molecular ends of the polymer produced by the above polymerization. Then, acetonitrile was distilled off by heating under reduced pressure, and the salt produced by the silylation was collected by filtration. Thus, (CF ₃ CH ₂ CH ₂ ) (Me) SiO units: 88.2 mol% (C ₆ H ₅ ) SiO _1.5 units: 2.94 mol% (CH ₂ = CH) (Me) ₂ SiO _0.5 units: 8.82 A branched organopolysiloxane (A-2) consisting of mol% and having a viscosity of 2500 cP was obtained.

Preparation of Composition II for Silicone Gel To 100 parts of the above branched organopolysiloxane (A-2), a vinylsiloxane complex of chloroplatinic acid was added, and further 0.1 part of ethynylcyclohexanol was added to obtain a uniform composition. Mixed in. Then, 4.1 parts of the hydrogen polysiloxane (B-1) used in Example 1 was added to the obtained mixture and mixed uniformly. The vinylsiloxane complex of chloroplatinic acid is the branched organopolysiloxane (A-2).
And an organohydrogenpolysiloxane (B-1) were added in an amount such that the amount of platinum was 5 ppm. Thus, the composition II for silicone gel was prepared.

Physical Properties Test of Cured Gel The composition II for silicone gel obtained above was subjected to 1 at 150 ° C.
It was heat-cured for a time to obtain a transparent gel-cured product. With respect to this gel cured product, penetration measurement at 25 ° C. and −50 ° C. and gasoline immersion test were carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 Preparation of Linear Organopolysiloxane (D-1) Two Compounds: [(CF ₃ CH ₂ CH ₂ ) (Me) SiO] ₃ 468.0 g [(CH ₂ = CH)] 18.6 g of (Me) ₂ Si] ₂ O was charged into a 1000 ml flask, 0.24 g of trifluoromethanesulfonic acid was further added as an equilibration catalyst, and the mixture in the flask was stirred at 25 ° C. for 8 hours.

Then, 10 g of sodium hydrogen carbonate was added to the above mixture in the 1000 ml flask and stirred for 3 hours to neutralize the equilibrated catalyst. Next, sodium hydrogen carbonate and the neutralized salt were separated by filtration, and the low boiling point compound was distilled off by heating under reduced pressure. Thus, the following formula:

[Chemical 3] And a linear organopolysiloxane (D-1) having a viscosity of 900 cP was obtained.

Preparation of Composition III for Silicone Gel To 100 parts of the above linear organopolysiloxane (D-1), a vinylsiloxane complex of chloroplatinic acid was added, and further 0.1 part of ethynylcyclohexanol was added, Mix evenly. Then, 8.2 parts of the hydrogen polysiloxane (B-1) used in Example 1 was added to the obtained mixture and mixed uniformly. Incidentally, the vinyl siloxane complex of chloroplatinic acid is the linear organopolysiloxane (D-1)
And an organohydrogenpolysiloxane (B-1) were added in an amount such that the amount of platinum was 5 ppm. Thus, the composition III for silicone gel was prepared.

Physical property test of gel cured product The composition III for silicone gel obtained above was heat cured at 150 ° C. for 1 hour to obtain a transparent gel cured product. With respect to this gel cured product, penetration measurement at 25 ° C. and −50 ° C. and gasoline immersion test were carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 Production of Linear Organopolysiloxane (D-2) The following three compounds: [(CF ₃ CH ₂ CH ₂ ) (Me) SiO] ₃ 312.0 g [(Me) ₂ SiO] ₄ 74.0 g [(CH ₂ = CH) (Me) ₂ Si] ₂ O 18.6 g was charged into a 1000 ml flask, 0.20 g of trifluoromethanesulfonic acid was added as an equilibration catalyst, and the mixture in the flask was heated at 25 ° C. Stir for 8 hours.

Then, 10 g of sodium hydrogen carbonate was added to the above mixture in the 1000 ml flask and stirred for 3 hours to neutralize the equilibrated catalyst. Next, sodium hydrogen carbonate and the neutralized salt were separated by filtration, and the low boiling point compound was distilled off by heating under reduced pressure. Thus, the following formula:

[Chemical 4] , A linear organopolysiloxane (D-2) having a viscosity of 800 cP was obtained. Incidentally, R in all the RMeSiO units (R is a group selected from the group consisting of a methyl group and a 3,3,3-trifluoropropyl group) contained in the linear organopolysiloxane (D-2) is 3,3. The proportion of units having a 3,3-trifluoropropyl group is 67%, and the proportion of units having R 3 is a methyl group is 33%.

Preparation of Composition IV for Silicone Gel Next, vinyl siloxane complex of chloroplatinic acid was added to 100 parts of the linear organopolysiloxane (D-2), and 0.1 part of ethynylcyclohexanol was added. And mixed evenly. Then, 8.0 parts of the hydrogen polysiloxane (B-1) used in Example 1 was added to the obtained mixture and mixed uniformly. Incidentally, the vinyl siloxane complex of chloroplatinic acid is a linear organopolysiloxane (D-2) and an organohydrogenpolysiloxane (B-
The platinum content was 5 ppm with respect to the total of 1) and. Thus, the composition IV for silicone gel was prepared.

Physical Property Test of Cured Gel: The composition IV for silicone gel obtained above was subjected to 1 at 150 ° C.
It was heat-cured for a time to obtain a transparent gel-cured product. With respect to this gel cured product, penetration measurement at 25 ° C. and −50 ° C. and gasoline immersion test were carried out in the same manner as in Example 1. The results are shown in Table 1. According to this Comparative Example 2, dimethylsiloxane (Me ₂ Si) was added to the linear organopolysiloxane.
When the content of O) unit is introduced to reduce the content of 3,3,3-trifluoropropyl group, the penetration at -50 ° C can be improved, that is, the deterioration of flexibility at low temperature can be prevented. ,
It was confirmed that the swelling property against gasoline was large and the solvent resistance was lowered.

[0052]

[Table 1]

[0053]

The silicone gel composition of the present invention has excellent solvent resistance to gasoline and the like, and can form a silicone gel cured product which does not lose its flexibility even at low temperatures.

Claims (2)

[Claims] 1. (A) (CF ₃ -CH ₂ -CH ₂ ) (CH ₃ ) SiO unit 70.0-98.5 mol%, RSiO _1.5 unit 0.5-10.0 mol%, and (CH ₂ = CH) (CH ₃ ). ₂ SiO _0.5 unit 1.0 to 10.0 mol% [wherein R is a group selected from the group consisting of a 3,3,3-trifluoropropyl group, a phenyl group, a methyl group and a vinyl group. ] 100 parts by weight of a branched organopolysiloxane containing a vinyl group (B) 0.1 to 30 parts by weight of an organohydrogenpolysiloxane containing at least one hydrogen atom bonded to a silicon atom in one molecule, and (C) A solvent-resistant silicone gel composition containing an addition reaction catalyst. 2. The solvent resistant silicone gel composition according to claim 1, wherein the component (A) is a methyl-3,3,3-trifluoropropylsiloxane cyclic trimer in the presence of a pentacoordinated silicon catalyst. Those derived from a ring-opening polymerization product obtained by ring-opening polymerization at 50 ° C or lower.