JPH06256660A - Fuluorosilicone rubber composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition improved in adhesiveness by using an epoxyhydrogenpolysiloxane as the crosslinking agent. CONSTITUTION:This rubber composition is prepared by mixing a vinylfluoropolysiloxane represented by formula I (wherein Vi is vinyl; R<1> is 1-8C alkyl or phenyl; R is 1-8C perfluoroalkyl; (m) is an integer of 10 or greater; and (n) is an integer of 1 or greater) and having a content of perfluoroalkyl- siloxane units of 50mol% or above with an epoxyhydrogenpolysiloxane represented by average compositional formula II (wherein R<2> is an epoxy organic group; R<3> is H or an (un)substituted monovalent hydrocarbon group; at least one of R<3> groups is H; 0<c<=1; 1<=d<3; and 1.5<=c+d<=3) and a platinum group metal catalyst (C) (e.g. platinum). Component B is used in such an amount as to provide 1.5-4 hydrogen atoms bonded to the silicon atoms of component B per vinyl group of component A. Component C is used in an amount of 0.1-100ppm based on the total of components A and B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorosilicone rubber composition capable of forming a cured product having good adhesion to various substrates.

[0002]

2. Description of the Related Art Conventionally, as a curable fluorosilicone rubber composition, a vinyl group-terminated fluoropolysiloxane and a hydrogen polysiloxane containing a perfluoroalkyl group or an H (R) ₂ SiO _0.5 unit (R is There is known a type in which a cured product is formed by addition-curing an organohydrogenpolysiloxane having a hydrocarbon group such as an alkyl group) in the presence of a platinum catalyst. These fluorosilicone rubber compositions have excellent solvent resistance, moisture resistance and the like, and are useful as protective coating agents for electric and electronic parts.

[0003]

However, the conventionally known fluorosilicone rubber composition has a drawback in that the adhesiveness to various substrates is insufficient. Therefore, various adhesion aids have been added to this composition to improve the adhesion to various substrates. Therefore, the higher the content of the fluoroalkyl group in the composition, the poorer the compatibility of these adhesion aids, the more impaired the transparency, and the more difficult it is to obtain a cured product having stable physical properties. There was a problem.

Therefore, an object of the present invention is to form a cured product having excellent adhesiveness to various substrates,
It is an object of the present invention to provide a fluorosilicone rubber composition having good compatibility between main constituents.

[0005]

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

[Chemical 2] In the formula, Vi is a vinyl group, R ¹ may be the same or different, is a group selected from the group consisting of an alkyl group having 1 to 8 carbon atoms and a phenyl group, and R f is a group having 1 carbon atom.
To 8 are perfluoroalkyl groups, m is an integer of 10 or more, and n is an integer of 1 or more, which is a vinyl group-containing fluoropolysiloxane represented by the following siloxane units having a perfluoroalkyl group. Provided is a fluorosilicone rubber composition containing a content of 50 mol% or more, (B) an epoxy group-containing hydrogen polysiloxane, and (C) a platinum group metal-based catalyst.

An important feature of the present invention is that an epoxy group-containing hydrogen polysiloxane is used as a crosslinking agent (component (B)). This product not only has excellent compatibility with the vinyl group-containing fluoropolysiloxane of component (A), but also has good self-adhesiveness, and has succeeded in achieving the above-mentioned problems.

Component (A) In the composition of the present invention, it is the base polymer (A)
As the component, the vinyl group-containing fluoropolysiloxane represented by the general formula (1) is used. In this general formula (1), R ¹ is a group selected from the group consisting of an alkyl group having 1 to 8 carbon atoms and a phenyl group, and preferably a methyl group. Rf is a perfluoroalkyl group having 1 to 8 carbon atoms, preferably 3,3,3
A trifluoropropyl group. Further, m is 10 or more and n is an integer of 1 or more, but the content of the siloxane unit having a perfluoroalkyl group is 5
It is preferably 0 mol% or more. That is, when the content of the siloxane unit is less than 50 mol%, preferable properties of the fluoropolysiloxane are not exhibited. The vinyl group-containing fluoropolysiloxane preferably has a viscosity at 25 ° C. of 300 cP or more. If the viscosity is too low (that is, the degree of polymerization is low), the mechanical strength of the cured product formed may be unsatisfactory.

Component (B) The component (B) is a cross-linking agent and is a hydrogen polysiloxane having at least one hydrogen atom bonded to a silicon atom in one molecule. That is, the hydrogen atom bonded to the silicon atom and the vinyl group in the component (A) which is the base polymer undergo an addition curing reaction to form a cured product.

According to the present invention, an epoxy group-containing hydrogen polysiloxane is used as the crosslinking agent component. This compound has the characteristics that it has good self-adhesiveness and very good compatibility with the component (A). That is, since the organopolysiloxane as the component (A) contains a large amount (50 mol% or more) of siloxane units having a perfluoroalkyl group, the compatibility with ordinary hydrogen polysiloxane is extremely poor. Use of a hydrogen polysiloxane having a fluoroalkyl group such as a trifluoropropyl group solves the problem of compatibility with the component (A), but this causes a significant increase in cost and is not practical. However, in the present invention, surprisingly, not only the adhesiveness but also the compatibility with the component (A) was effectively improved by using the hydrogen polysiloxane having an epoxy group. The epoxy group-containing hydrogen polysiloxane is cheaper than the fluoroalkyl group-containing hydrogen polysiloxane, and the cost problem is effectively solved. Therefore, according to the present invention, the adhesiveness of the cured product to various substrates can be improved, and the transparency of the composition can be secured because the compatibility of the components (A) and (B) is good. It is.

This epoxy group-containing hydrogen polysiloxane has, for example, the following average composition formula (2): (R ² ) _C (R ³ ) _d SiO _{(4-cd) / 2} (2) where R ² is An organic group containing an epoxy group, R
³ may be the same or different and each is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and among all R ³ ,
At least one is a hydrogen atom, c and d are 0 <c
≦ 1,1 ≦ d <3,1.5 ≦ c + d ≦ 3 (preferably 1.8)
It is a number that satisfies ≦ c + d ≦ 2.2).

In the average composition formula (2), the organic group R ² containing an epoxy group is represented by the following formula (3) and the following formula (4):

[0012]

[Chemical 3]

[0013]

[Chemical 4]

[In the above formulas (3) and (4), X
The following formulas: - (CH _{2) p} - or _{- (CH 2) q -O- (} C
H ₂ ) _r − (p is an integer of 1 to 6 and q and r are integers of 1 to 3) are represented by the following formula: be able to.

Further, as the unsubstituted or substituted monovalent hydrocarbon group of R ³ , a methyl group, an ethyl group, a propyl group,
An alkyl group such as a butyl group; a cycloalkyl group such as a cyclohexyl group; an aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a benzyl group and a phenylethyl group; some or all of the hydrogen atoms of these groups are halogen atoms. And the like, such as a chloromethyl group and a 3,3,3-trifluoropropyl group; and the like, and those having 1 to 10 carbon atoms are preferable.

Typical examples of such an epoxy group-containing hydrogen polysiloxane include, but are not limited to, the followings.

[0017]

[Chemical 5]

[0018]

[Chemical 6]

[0019]

[Chemical 7]

[0020]

[Chemical 8]

The amount of the component (B) to be blended is not particularly limited, but in general, one vinyl group in the fluoropolysiloxane of the component (A) is bonded to the silicon atom in the component (B). It is used in a ratio such that the number of hydrogen atoms is 1.5 to 4.

Component (C) The platinum group metal-based catalyst of component (C) is a catalyst for carrying out an addition curing reaction between the vinyl group in component (A) and the silicon-bonded hydrogen atom in component (B). In addition, those generally used in addition-curable silicone rubber compositions can be used. For example, there are platinum-based, palladium-based, and rhodium-based catalysts, and platinum-based catalysts are preferably used from the viewpoint of cost and the like. Examples of platinum-based catalysts include platinum simple substance, H ₂ PtCl ₆ · nH ₂ O,
NaHPtCl ₆ · nH ₂ O, KHPtCl ₆ · nH ₂
O, Na ₂ PtCl ₂ · nH ₂ O, K ₂ PtCl ₆ · n
H ₂ O, PtCl ₄ · nH ₂ O, PtCl ₂ , Na ₂ P
Examples thereof include tCl ₄ .nH ₂ O and H ₂ PtCl ₄ .nH ₂ O, and complexes of these platinum compounds with hydrocarbon, alcohol or vinyl group-containing cyclic siloxane.

The amount of these platinum group metal-based catalysts to be used can be a catalytic amount, for example, 0.1 to 100 ppm of platinum based on the total amount of the components (A) and (B).

Other Compounding Agents In addition to the above-mentioned components (A) to (C), various additives known per se can be added to the composition of the present invention depending on the application. For example, in order to further improve the adhesiveness at a low temperature of 100 ° C. or lower, an ester siloxane represented by the following formula (5) is added per 100 parts by weight of the component (A):
It can be added in an amount of 0.01 to 5 parts by weight.

[0025]

[Chemical 9]

In the above formula, R ⁴ may be the same or different and is an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, for example, an alkyl group having 1 to 4 carbon atoms, s is 0 or a positive integer.

In addition, reinforcing inorganic fillers such as fumed silica and fumed titanium dioxide, and non-reinforcing inorganic fillers such as finely divided quartz, calcium carbonate, calcium silicate, titanium dioxide, ferric oxide and carbon black. It can be blended as needed. These inorganic fillers are generally added to 100 parts by weight of all components of the composition.
Used in amounts up to 200 parts by weight.

Fluorosilicone Rubber Composition The rubber composition of the present invention can be divided into two liquids and the two liquids can be mixed and cured in the same manner as a usual silicone rubber composition, but a small amount of It is also possible to add a curing inhibitor (for example, acetylene alcohol, etc.) or the like and use it as one liquid. In this case, to make each of the above components into two liquids,
It is preferable to mix the vinyl group-containing fluoropolysiloxane of the component (A) and the catalyst of the component (C) as the first liquid and to use the epoxy group-containing hydrogen polysiloxane of the component (B) as the second liquid. . The fluorosilicone rubber composition of the present invention has properties peculiar to fluororubber, and also has excellent adhesiveness and transparency to various base materials, and is used as a protective coating material for electric / electronic parts and the like. Extremely useful.

[0029]

[Examples] In the following examples, "parts" means "parts by weight", and viscosity means a value measured at 25 ° C. Experimental Example 1 The following formula (6):

[0030]

[Chemical 10]

The content of the fluoroalkyl group-containing siloxane unit is 98 mol%, 50 mol% and 30 mol.
To 100 parts of each fluorosilicone polymer having a viscosity of 5,000 cP and a viscosity of 5,000 cP, 10 parts of each of the following adhesion promoters or cross-linking agents were added, and the compatibility of each composition was examined. The results are shown in Table 1.

[0032]

[Chemical 11]

[0033]

[Chemical 12]

[0034]

[Chemical 13]

[0035]

[Chemical 14]

[0036]

[Chemical 15]

[0037]

[Chemical 16]

[0038]

[Chemical 17]

[0039]

[Chemical 18]

[0040]

[Table 1]

From the results in Table 1, it is understood that the compatibility with the fluorosilicone polymer is improved by containing the epoxy group.

Example 1 A fluorosilicone polymer 100 represented by the same formula (6) as in Experimental Example 1 and having the same viscosity, but having a fluoroalkyl group-containing siloxane unit content of 70 mol%. 1.7 parts of the epoxy group-containing hydrogen siloxane of Experimental Example 1 (one mole of 1,3,5,7-tetramethylsiloxane partially added with 1 mole of allyl glycidyl ether), chloroplatinic acid 0.05 part of an octyl alcohol-modified solution (2% by weight of platinum) was added and well stirred to prepare a silicone rubber composition.
This composition was applied to 4 types of substrates shown in Table 2 by 5 cm.
A (vertical) × 2 cm (horizontal) × 2 mm (thickness) sheet was applied and cured by heating at 150 ° C. for 4 hours to obtain a test piece. The test pieces were subjected to a qualitative adhesion test by the following method, and the results are shown in Table 2.

Adhesion Test When the cured product was destroyed using a micro spatula and peeled from the substrate, the ratio between the cohesive failure portion and the peeled portion was observed and the adhesiveness thereof was judged. Criteria ○: Good adhesion (cohesive failure rate of 80% or more) Δ: Partial adhesion (cohesive failure rate of 80 to 20% or more) ×: No adhesion (cohesive failure rate of 20% or less)

Comparative Example 1 The same as Example 1 except that 1.2 g of the hydrogenene polysiloxane of Experimental Example 1 (containing no epoxy group) was used in place of the above-mentioned epoxy group-containing hydrogenene siloxane. Similarly, a composition was prepared, and a test piece was prepared to perform an adhesion test. The results are shown in Table 2.

Comparative Example 2 A composition was prepared and test pieces were prepared in the same manner as in Comparative Example 1 except that the amount of the hydrogenene polysiloxane used in Experimental Example 1 was 0.9 g. Then, an adhesion test was performed. The results are shown in Table 2.

[0046]

[Table 2]

From the results shown in Table 2, it was confirmed that the composition of the present invention (Example 1) had excellent adhesiveness to an aluminum / nickel silicon wafer and glass. On the other hand, the composition containing no epoxy group (Comparative Example 1) has poor adhesion to the substrate, and it is necessary to add some kind of adhesion aid.

Example 2 100 parts of the same fluorosilicone polymer as used in Example 1 was added to 50 parts of high-purity fused silica having an average particle size of 2 μm.
Parts, 1.7 parts of the same epoxy group-containing hydrogenene siloxane as in Example 1 and 0.05 parts of an octyl alcohol-modified solution of chloroplatinic acid were added and well stirred to prepare a silicone rubber composition. A test piece was prepared in the same manner as in Example 1,
The same adhesion test as in Example 2 was performed, and the physical properties of the cured product
It was measured according to JIS K 6301. The results are shown in Table 3.

Example 3 A silicone rubber composition was prepared in the same manner as in Example 2 except that the compound of Experimental Example 1 (1.7 parts) was used in place of the epoxy group-containing hydrogen siloxane used in Example 2. The product was prepared, a test piece was prepared, and the same test as in Example 2 was performed. The results are shown in Table 3.

[0050]

[Table 3]

Experimental Example 2 Cured products of Examples 1, 2 and the dimethyl silicone rubber composition were tested for solvent resistance and moisture permeability. The results are shown in Table 4. The dimethylsilicone rubber composition used for comparison has the following formula:

[0052]

[Chemical 19]

And 100 parts of vinyl group-containing dimethylpolysilicone having a viscosity of 5000 cP, the following formula:

[0054]

[Chemical 20]

This was prepared by adding 2.0 parts of a hydrogenene polysiloxane having a viscosity of 10 cP and 0.05 part of an octyl alcohol-modified solution of chloroplatinic acid and thoroughly stirring. A rubber cured product [hardness: 20 (JIS-A)] obtained by heat molding at 150 ° C./4 hr was compared with the cured products obtained in Examples 1 and 2. The moisture resistance is evaluated by measuring the weight change according to JIS K 6301, and the moisture permeability is
It was evaluated by measuring the weight change according to JIS Z 0208.

[0056]

[Table 4]

[0057]

By using the epoxy group-containing hydrogen polysiloxane as a cross-linking agent, a cured product having self-adhesiveness can be obtained without adding other additives for improving adhesion. In addition, this epoxy group-containing cross-linking agent is surprisingly excellent in compatibility with the vinyl group-containing fluoropolysiloxane that is the base polymer, which makes it possible to obtain a transparent cured product and expand its applications. is there. Furthermore, the obtained cured product has excellent solvent resistance and moisture resistance,
It can be widely used as a protective coating agent and adhesive for electronic and electric parts.

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[Procedure amendment]

[Submission date] October 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

[Chemical 12]

Claims (2)

[Claims] (A) The following general formula (1): In the formula, Vi is a vinyl group, R ^1's may be the same or different, and have 1 to 10 carbon atoms.
A group selected from the group consisting of an alkyl group of 8 and a phenyl group, Rf is a perfluoroalkyl group having 1 to 8 carbon atoms, m is an integer of 10 or more, n is an integer of 1 or more, A vinyl group-containing fluoropolysiloxane represented by the above, wherein the content of the siloxane unit having a perfluoroalkyl group is 50 mol% or more, (B) an epoxy group-containing hydrogen polysiloxane, (C) a platinum group metal A fluorosilicone rubber composition containing a base catalyst. 2. A cured product obtained by curing the silicone rubber composition according to claim 1.