JP3278253B2 - Curable silicone rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an addition-curable curable silicone rubber composition, and more particularly to a cured composition having good rubber properties and strength properties and improved adhesion to various substrates. The present invention relates to a water-soluble silicone rubber composition.

[0002]

2. Description of the Related Art An addition-curable silicone rubber composition containing a vinyl group-containing organopolysiloxane and a SiH group-containing organohydrogenpolysiloxane has properties such as weather resistance and heat resistance, hardness and elongation. It is used for various applications because it forms a cured product excellent in rubber-like properties. In recent years, a silicone rubber composition that can form a cured product having particularly high strength and high hardness and excellent adhesion to various substrates has been desired.

[0003]

In general, it has been known that, in addition-curable silicone rubber compositions, the strength of the cured product can be improved by blending a resin-like organopolysiloxane. I have.

However, when the strength of the cured product is increased by the resin-like organopolysiloxane, rubber properties such as elongation are impaired, and the adhesion to various substrates is not improved.

Accordingly, an object of the present invention is to provide an addition-curable silicone rubber composition capable of forming a cured product having improved strength and adhesiveness without impairing rubber properties such as elongation.

[0006]

According to the present invention, (A) the following general formula (1):

Embedded image In the formula, R ¹ is a same or different group, a monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, and m and n are 0 or a positive integer. And
Organopolysiloxane having a viscosity (25 ° C.) is 3,000~20,000cSt, (B) SiO _{2 ^{units, Vi (R 2) 2 SiO}} 0.5 units and R ² ₃ SiO _0.5 units (wherein, Vi is a vinyl group, R ² is ,
(C) an organopolysiloxane having a resin structure comprising a monovalent hydrocarbon group containing no aliphatic unsaturated bond), and (C) the following general formula (2):

Embedded image In the formula, R ³ is a hydrogen atom or a monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, and may be the same or different. R ⁴ is the same or different group. A monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, p is an integer of 10 to 400 , and q is 0 or a positive integer. A polysiloxane, (D) an organosilane or an isocyanurate modified with an organosiloxane, and (E) a platinum group catalyst, wherein the component (B) is a mixture of the component (A) and the component (B). 37-5 per total amount
A curable silicone rubber composition is provided, which is blended in an amount of 2% by weight.

[0007]

That is, in the addition-curable silicone rubber composition of the present invention, the vinyl group-containing organopolysiloxane (A) as a base component has a viscosity at 25 ° C.
A resin having a very limited range of 3,000 to 20,000 cSt is used, and an organopolysiloxane having a resin structure (B) is used in an amount of 37 to 52% by weight based on the total amount of the component (A).
The cured product formed from such a composition has high tensile strength and elongation.

In the present invention, this range of viscosity and compounding amount is extremely critical and has been found by conducting many experiments. That is, even if one of the viscosity of the organopolysiloxane (A) and the blending amount of the organopolysiloxane (B) is out of the above range, a cured product satisfying both the elongation and the tensile strength can be formed. Can not.

For example, in an addition-curable composition containing a resin-like organopolysiloxane, a vinyl-containing organopolysiloxane (A) as a base component is used.
FIG. 1 shows a curve plotting the tensile strength, elongation, and hardness of the cured product with respect to the viscosity of the resin, and FIG. 1 shows a curve plotting the same cured product characteristics with respect to the blending amount of the resin-like organopolysiloxane. 2 is shown. As is apparent from these figures, the tensile strength shows a peak value in the range of the viscosity of the organopolysiloxane (A) and the amount of the resinous organopolysiloxane, and the elongation and hardness can be satisfied. Indicates the value. In particular, it is quite surprising that the elongation and hardness curves are linear functions, whereas the tensile strength curves are quadratic functions and show peak values. Under conditions,
It is considered that the resin-like organopolysiloxane is taken into the cured product in a certain uniform distribution state, and in this connection, the resin exhibits high tensile strength and elongation.

In the present invention, the modified isocyanurate of the component (D) acts as an adhesion aid,
By blending such components, the cured product exhibits excellent adhesion to various substrates.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION (A) Vinyl Group-Containing Organopolysiloxane The vinyl group-containing organopolysiloxane (A) which is a base component in the silicone rubber composition of the present invention is represented by the general formula (1). As mentioned above, it is extremely important that the viscosity at 25 ° C. is in the range of 3,000 to 20,000 cSt. If the viscosity is lower than 3,000 cSt, the resulting cured product has unsatisfactory tensile strength and elongation, and if the viscosity is higher than 20,000 cSt, the cured product has unsatisfactory tensile strength (see FIG. 1).

In the general formula (1), a monovalent unsubstituted or substituted hydrocarbon group R having no aliphatic unsaturated bond
^{As 1} , a lower alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a cycloalkyl group such as a cyclohexyl group, a phenyl group, an aryl group such as a tolyl group, a xylyl group, an aralkyl group such as a benzyl group, and Examples thereof include groups in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms, cyano groups, and the like, for example, chloromethyl groups, cyanoethyl groups, and 3,3,3-trifluoropropyl groups. Among these, the number of carbon atoms is 1 to 10,
Particularly, those in the range of 1 to 6 are preferable.

Further, n and m are 0 or a positive integer, and in particular, are numbers such that the viscosity at 25 ° C. is in the above-mentioned range. Generally, it is an integer satisfying 0 <n + m ≦ 10,000, preferably 0 <n + m ≦ 2,000 and 0 <m
/(N+m)≦0.2.

In the present invention, typical examples of the vinyl group-containing organopolysiloxane include, but are not limited to, those represented by the following formula. In the following formula, t is a number such that the viscosity at 25 ° C. is in the above-described range.

[0015]

Embedded image

(B) An organopolysiloxane having a resin structure
Organopolysiloxane resin structure of emission component (B),
It is blended to improve the physical strength of the cured product, and as described above, is blended in an amount of 37 to 52% by weight based on the total amount of the component (A).

The organopolysiloxane having a resin structure has the following units: SiO ₂ unit (hereinafter sometimes referred to as a unit), Vi (R ² ) ₂ SiO _0.5 unit (hereinafter sometimes referred to as b unit). and, R ² ₃ SiO _0.5 units (hereinafter sometimes referred to as c units), which consist, usually, it is preferable that the weight average molecular weight in the range of 2000-4000. Here, Vi is a vinyl group, R ²
Represents a monovalent hydrocarbon group containing no aliphatic unsaturated double bond. As the monovalent hydrocarbon group R ² , the above-mentioned general formula (1)
The same as R ^{1 in the above} can be exemplified, and preferred are a methyl group, a phenyl group and the like.

Here, each unit has a molar ratio of (b + c) /a=0.3 to 3, especially 0.7 to 1.0, c / a = 0.01 to 1, especially 0.07 to 0.15. Preferably they are combined.

Such an organopolysiloxane having a resin structure can be easily synthesized by combining the compounds serving as unit sources so as to have the above-mentioned molar ratio, and for example, performing co-hydrolysis in the presence of an acid. it can. Here, examples of the a unit source include sodium silicate, alkyl silicate, polyalkyl silicate, and silicon tetrachloride. The b unit source is Vi
(R ² ) ₂ SiOSi (R ² ) ₂ Vi, Vi (R ² ) ₂
SiCl, etc. can be exemplified. Further, as the c unit source, (R ² ) ₃ SiOSi (R ² ) ₃ , (R ² )
₃ SiCl, and the like. In the above formula, Vi and R ² are as described above.

(C) Organohydrogen polysiloxane
The organohydrogenpolysiloxane of the sun component (C) acts as a crosslinking agent, and the cured product is formed by an addition reaction between the SiH group in the component and the vinyl group in the components (A) and (B). To form.

Such an organohydrogenpolysiloxane is represented by the general formula (2). In the general formula (2), R ³ is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and specific examples of the monovalent hydrocarbon group include: And the same groups as those exemplified for R ¹ in the general formula (1). Of these, preferred are a methyl group and a phenyl group.

P is from 10 to 40 from the viewpoint of adhesiveness.
0, preferably Ru integer der of 15 to 100. Although q is 0 or a positive integer, it is preferable that q = 0 from the viewpoint of adhesiveness.

The organohydrogenpolysiloxane has a molar ratio of SiH groups of 0.1 to 3.0, especially 1.2 to 2.0, per the total amount of vinyl groups in the components (A) and (B). Preferably it is used in a ratio.

(D) Modified Isocyanurate In the present invention, the modified isocyanurate of the component (D) is modified with an organosilane or an organosiloxane, and is disclosed, for example, in Japanese Patent Publication No. 45-23354. It is known. That is, the modified isocyanurate is easily synthesized by an addition reaction of an isocyanurate having an alkenyl group such as a vinyl group or an allyl group with an organosilane or an organosiloxane having a SiH group in the presence of a platinum-based catalyst. be able to. Representative examples of the modified isocyanurate include, but are not limited to, the following.

[0025]

Embedded image

The modified isocyanurate is blended in an amount of 0.05 to 5.0 parts by weight, particularly 0.1 to 5.0 parts by weight, per 100 parts by weight of the total of the components (A) and (B). Is preferred. If the compounding amount is less than this range, the adhesiveness of the cured product to various substrates is not sufficient, and if the compounding amount is larger than the above range, there is no further effect, and it becomes economically rather negative. Alternatively, physical properties of the cured product such as tensile strength and elongation may be impaired.

(E) Platinum Group Metal Catalyst This catalyst component is used to cause an addition curing reaction of the composition of the present invention, and includes platinum, palladium and rhodium catalysts. From the viewpoint of cost, cost, etc., for example, H ₂ PtCl ₆ .mH ₂ O, K
₂ PtCl ₆ , KHPtCl ₆ · mH ₂ O, K ₂ PtC
l ₄ , K ₂ PtCl ₄ mH ₂ O, PtO ₂ · mH ₂ O,
PtCl ₄ .mH ₂ O, PtCl ₂ , H ₂ PtCl _4.
Examples thereof include mH ₂ O, (m is a positive integer), and complexes thereof with hydrocarbons, alcohols, or vinyl group-containing organopolysiloxanes. These may be used alone or in combination of two or more. But can be used.

The amount of these catalyst components may be a so-called catalyst amount, and is usually 100% in total of the components (A) to (C).
It is used in the range of 0.1 to 100 ppm in terms of platinum group metal per part by weight.

Other Compounding Agents In addition to the above-mentioned components (A) to (E), various additives known per se can be added to the composition of the present invention, if necessary. For example, fumed silica, reinforcing inorganic fillers such as fumed titanium dioxide, calcium carbonate, calcium silicate, titanium dioxide, ferric oxide, non-reinforcing inorganic fillers such as carbon black,
The components (A) to (E) can be appropriately added in a range of 200 parts by weight or less per 100 parts by weight of the total amount of the components.

Silicone Rubber Composition The silicone rubber composition of the present invention is prepared by uniformly mixing the above-described components, but is usually stored in two liquids so that curing does not proceed, and is used. Sometimes 2
The liquid is mixed and cured. Of course, a small amount of a curing inhibitor such as acetylene alcohol may be added and used as one liquid. This composition is cured immediately by heating if necessary, and forms a high-hardness elastic cured product having a high elongation and tensile strength, and the cured product has an adhesive property to various substrates such as metals. And can be widely used as a protective coating agent for electric and electronic parts, an adhesive and the like.

[0031]

EXAMPLES In the following examples, parts mean parts by weight,
The viscosity indicates a value measured at 25 ° C.

Experimental Example 1 The following formula:

[0033]

Embedded image

In each of 50 parts of various polysiloxanes (VF) having different viscosities, 50 mol% of SiO ₂ units, 42.5 mol% of (CH ₃ ) ₃ SiO _0.5 units, and Vi
50 parts of vinylmethylsiloxane (VMQ) having a resin structure consisting of _0.5 mol% of (CH ₃ ) ₂ SiO _0.5 unit,
The amount of the iH group is 1.5 times the mol of the total amount of the vinyl groups in the VF and VMQ components by the following formula:

[0035]

Embedded image

A modified isocyanurate obtained by adding 1 mol of trimethoxysilane to 1 mol of an organohydrogenpolysiloxane or tetraallyl isocyanurate represented by the formula:
0.25 parts and 0.05 parts of an octyl alcohol-modified solution of chloroplatinic acid were added and stirred well to prepare a silicone rubber composition. The composition was heat-molded at 150 ° C. for 4 hours to form a cured product, and the tensile strength, hardness (measured using an A-type spring tester) and elongation were measured in accordance with JIS K 6301. . Each measurement result is shown in FIG. 1 as a diagram plotted against the viscosity of VF.

Experimental Example 2 A VF having a viscosity of 5,000 cSt was used,
A silicone rubber was prepared and a cured product was formed in the same manner as in Experimental Example 1 except that the amount of was changed, and the tensile strength, hardness and elongation were measured. Each measurement result,
FIG. 2 is a graph plotted against the VMQ content (percentage of the total amount with VF).

Experimental Example 3 50 parts of VF used in Experimental Example 2 and VM used in Experimental Example 1
Q (SiVi bond 0.043 as the total amount of VF and VMQ)
mol / 100 g) 50 parts, the organohydrogenpolysiloxane used in Experimental Example 1 (SiH bond is 1.50 mol /
4.3 g of the modified isocyanurate used in Experimental Example 1 and 0.05 part of an octyl alcohol-modified chloroplatinic acid solution were mixed, and a silicone rubber composition was prepared in the same manner as in Experimental Example 1. , A cured product was formed, and tensile strength, hardness and elongation, and adhesion to various substrates were measured. The results are shown in Table 1.

The evaluation of adhesiveness is as follows. ：: Complete adhesion △: Partially peeled ×: Peeled

Experimental Example 4 In Experimental Example 3, an organohydrogenpolysiloxane having a polymerization degree n of 38 (SiH bond of 1.55
mol / 100g) (containing 4.16 parts), a silicone rubber composition was prepared and a cured product was formed in the same manner as in Experimental Example 3 to obtain a tensile strength, hardness and elongation, and various base materials. The adhesion to was measured. The results are shown in Table 1.

Experimental Example 5 In Experimental Example 3, an organohydrogenpolysiloxane having a degree of polymerization n of 98 (SiH bond of 1.58
(contains mol / 100 g), a silicone rubber composition was prepared in the same manner as in Experimental Example 3 except that 4.1 parts were used, and a cured product was formed. Tensile strength, hardness and elongation, and various base materials The adhesion to was measured. The results are shown in Table 1.

EXPERIMENTAL EXAMPLE 6 In Experimental Example 3, 5.9 parts of an organohydrogenpolysiloxane having an average degree of polymerization of 5.5 (containing 1.09 mol / 100 g of SiH bonds) were used. A silicone rubber composition was prepared in the same manner as in Experimental Example 3, a cured product was formed, and tensile strength, hardness and elongation, and adhesion to various substrates were measured. The results are shown in Table 1.

Experimental Example 7 The following formula:

Embedded image The organohydrogenpolysiloxane represented by the formula (S
A silicone rubber composition was prepared in the same manner as in Experimental Example 3 except that 8.8 parts of iH bond was contained (containing 0.73 mol / 100 g), a cured product was formed, and tensile strength, hardness and elongation, and various The adhesion to the substrate was measured. Table 1 shows the results
It was shown to.

[0044]

[Table 1]

Experimental Example 8 In Experimental Example 3, an organohydrogenpolysiloxane having a polymerization degree n of 38 (SiH bond was 1.55
(contains mol / 100 g), a silicone rubber composition was prepared in the same manner as in Experimental Example 3 except that 8.32 parts was used, a cured product was formed, and the tensile strength, hardness and elongation, and adhesion to various substrates The properties were measured. The results are shown in Table 2.

Experimental Example 9 The amount of the organohydrogenpolysiloxane used was 5.54.
A silicone rubber composition was prepared and a cured product was formed in the same manner as in Experimental Example 8 except that the above parts were used, and tensile strength, hardness and elongation, and adhesion to various substrates were measured. The results are shown in Table 2.

Experimental Example 10 The amount of the organohydrogenpolysiloxane used was changed to 2.77.
A silicone rubber composition was prepared and a cured product was formed in the same manner as in Experimental Example 8 except that the above parts were used, and tensile strength, hardness and elongation, and adhesion to various substrates were measured. The results are shown in Table 2.

[0048]

[Table 2]

[0049]

According to the present invention, it is possible to form a cured silicone product having high tensile strength and elongation and excellent adhesion to various substrates.

[Brief description of the drawings]

FIG. 1 shows the measurement results of Experimental Example 1 showing the relationship between the viscosity of organopolysiloxane (A) and the tensile strength, elongation, and hardness of a cured product.

FIG. 2 shows the measurement results of Experimental Example 1 showing the relationship between the content of the organopolysiloxane (B) having a resin structure and the tensile strength, elongation, and hardness of the cured product.

Continuation of the front page (56) References JP-A-63-85497 (JP, A) JP-A-1-215857 (JP, A) JP-A-57-137355 (JP, A) JP-A-4-311765 (JP) , A) JP 49-6160 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/07 C08L 83/05 C08K 5/3477 C08K 5/541

Claims (1)

(57) [Claims] (A) The following general formula (1): In the formula, R ¹ is the same or different group and is a monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, and m and n are 0 or a positive integer. is, organopolysiloxane having a viscosity (25 ° C.) is 3,000~20,000cSt, (B) SiO _{2 ^{units, Vi (R 2) 2 SiO}} 0.5 units and R ² ₃ SiO _0.5 units (wherein, Vi is vinyl radical, R ² is
(C) an organopolysiloxane having a resin structure comprising a monovalent hydrocarbon group containing no aliphatic unsaturated bond) and (C) the following general formula (2): In the formula, R ³ is a hydrogen atom or a monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, and may be the same or different. R ⁴ is a same or different group. A monovalent unsubstituted or substituted hydrocarbon group having no aliphatic unsaturated bond, p is an integer of 10 to 400 , and q is 0 or a positive integer. A polysiloxane, (D) an isocyanurate modified with an organosilane or an organosiloxane, and (E) a platinum group catalyst. A curable silicone rubber composition which is blended in an amount of 37 to 52% by weight based on the total amount.