JPH0848885A - Curable silicone rubber composition for roll member - Google Patents

Abstract

PURPOSE:To obtain the subject composition having both of a vinyl-containing organocyclopolysiloxane and triazole compound and small compression permanent strain of a cured product. CONSTITUTION:This composition is obtained by blending (A) 100 pts.wt. of an organopolysiloxane of formula I [R<1> is a (substntuted)-monovalent hydrocarbon; (p) is 1.95 2.05] having >=2 aliphatic unsaturated hydrocarbons bonded to Si and 200-200000cSt viscosity at 25 deg.C with (B) 0.05-5 pts.wt. of a vinyl- containing organocyclopolysiloxane of formula II [R is a lower alkyl; (n) is 3-8] and (C) an organohydrodiene-polysiloxane of formula III (R<2> is an alkyl, phenyl, etc.; (q) is 0.002-1; (r) is l-2, with the proviso that (q+r) is 1.002-3] having >=2 hydrogen atoms bonded to Si in an amount enough to feed 0.5-5 hydrogen atoms of SiH based on one aliphatic unsaturated hydrocarbon group bonded to Si atom in the components A and B, (D) a platinum metal-based catalyst in an amount of 1-500ppm expressed in terms of a metal amount based on total amount of the components A and B and (E) 0.005-1 pts.wt. of a triazole- based compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable silicone rubber composition for roll members, and more particularly to a curable silicone rubber composition for roll members having a cured product with a small compression set.

[0002]

2. Description of the Related Art Curable silicone rubber compositions are used as various molded articles by curing at room temperature or under heating.

[0003]

However, a cured product of a conventional curable silicone rubber composition has a large compression set and is subjected to a long-term compression deformation, such as a roll member, a material for a connector of an automobile part, and the like. However, even if it can be used, there is a problem that the molding process is complicated because after curing, after curing, it is necessary to after-cure at high temperature for a long time to stabilize the cured product. Therefore, an object of the present invention is to provide a curable silicone composition for roll members, which has a small compression set of the cured product.

[0004]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have been known to be effective as a curing inhibitor in an addition curing reaction. An organocyclopolysiloxane,
A curable silicone rubber composition obtained by unexpectedly curing is obtained by having two components as an essential component together with a triazole compound known as a curing control agent in an addition curing reaction or a flame-retardant imparting agent for silicone rubber. The present invention has been accomplished by finding that the product has a small compression set and exhibits extremely sharp curing characteristics.

That is, in order to solve the above-mentioned problems, the present invention provides: (A) Average composition formula: (R ¹ ) _p SiO _{(4-p) / 2} (I) [wherein R ¹ is the same It may be different, and is an unsubstituted or substituted monovalent hydrocarbon group, p is a number of 1.95 to 2.05], and an aliphatic unsaturated hydrocarbon group bonded to a silicon atom in one molecule is 2 Have more than one and have a viscosity at 25 ° C
100 parts by weight of organopolysiloxane, 200 to 200,000 cSt, (B) General formula:

[0006]

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[In the formula, R is a lower alkyl group, and n is 3-8.
Vinyl group-containing organo siloxanes of 0.05 to 5 parts by weight, represented by an integer], (C) the average composition ^{_{formula: H q (R 2) r}} SiO (4-qr) / 2 (III) wherein , R ² may be the same or different, and an alkyl group,
A phenyl group or a trimethylsiloxy group, and q is 0.00
Is an integer of 2 to 1.0, r is a number of 1.0 to 2.0 (wherein q + r is 1.002 to 3.0)], and an organo having two or more hydrogen atoms bonded to a silicon atom in one molecule. Hydrogenene polysiloxane (A) A sufficient amount to provide 0.5 to 5 hydrogen atoms bonded to silicon atoms per one aliphatic unsaturated hydrocarbon group bonded to silicon atoms in the component (B) and in the component (B), (D) Platinum group metal catalyst Amount of platinum group metal of 1 to 500 ppm based on the total amount of component (A) and component (B), and (E) Triazole compound
The present invention provides a curable silicone rubber composition for roll members, which contains 0.005 to 1 part by weight.

The organopolysiloxane which is the component (A) of the composition of the present invention is represented by the above-mentioned average composition formula (I),
It has two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. Examples of the aliphatic unsaturated hydrocarbon group include a vinyl group and an allyl group, and a vinyl group is preferable. In addition to the aliphatic unsaturated hydrocarbon group, examples of the group bonded to a silicon atom include an aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group and an octyl group; an aromatic hydrocarbon group such as a phenyl group;
A hydrocarbon group in which a part of hydrogen atoms such as a 3,3,3-trifluoropropyl group is substituted with a halogen atom, and the like,
Usually a methyl group is common. However, in order to obtain a composition having high heat resistance or high refractive index, a phenyl group is preferable, and in terms of improving solvent resistance and oil resistance, 3,3,3
-Trifluoropropyl group is preferred. The organopolysiloxane is usually linear, but may be slightly branched. Further, the aliphatic unsaturated hydrocarbon group may be present at either the terminal of the molecular chain or the side chain, or may be present at both of them. The organopolysiloxane (A) has a viscosity at 25 ° C of 200 to 200,000 cS.
t is preferable, and from the viewpoint of workability of the obtained composition and physical properties of the cured product, it is preferably 200 to 100000 cSt. These organopolysiloxanes may be used alone or in combination of two or more.

The vinyl group-containing organocyclopolysiloxane which is the component (B) of the composition of the present invention is represented by the above general formula (II). In the general formula (II), R is a lower alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group and a butyl group, and preferably a methyl group or an ethyl group. n is an integer of 3 to 8, preferably an integer of 3 to 6. As the vinyl group-containing organocyclopolysiloxane represented by the general formula (II),
Industrially, methylvinylcyclotetrasiloxane is preferred. The blending ratio of the component (B) in the composition of the present invention is usually 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the component (A). If the blending amount of the component (B) is too small, the compression set of the cured product of the composition of the present invention is not reduced, and if it is too large, the cured product of the composition is hard.
May be brittle.

The organohydrogenpolysiloxane which is the component (C) is represented by the above average composition formula (III):
It has two or more hydrogen atoms bonded to silicon atoms in the molecule, and may have a linear, branched, or cyclic structure. R ² in the average composition formula (III)
Is an alkyl group, a phenyl group or a trimethylsiloxy group, q is a number of 0.002 to 1.0, and r is 1.0 to 2.0.
And q + r is 1.002 to 3.0, but usually q +
r is 1.952 to 3.0. Specific examples of the organohydrogen polysiloxane include those shown below.

[0011]

[Chemical 3] (However, a, b and c represent 0 or a positive integer, and d represents an integer of 2 or more.),

[0012]

[Chemical 4]

(Wherein R represents a hydrogen atom, a methyl group, an ethyl group, a propyl group or a trimethylsiloxy group) and

[0014]

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When a bifunctional organohydrogenpolysiloxane is used as the component (C), a trifunctional or higher functional organohydrogenpolysiloxane is added (Japanese Patent Publication No. 47-40447), or It is preferable to use an organopolysiloxane containing an aliphatic unsaturated hydrocarbon group bonded to a tri- or higher functional silicon atom in the organopolysiloxane as the component (A).

Further, the compounding amount of the component (C) is such that one hydrogen atom bonded to the silicon atom is added to one aliphatic unsaturated hydrocarbon group bonded to the silicon atom in the component (A) and the component (B).
It is an amount sufficient to provide 0.5 to 5, preferably 1 to 2.

As the platinum group metal-based catalyst which is the component (D), those generally known as catalysts for addition reaction can be mentioned, for example, platinum black or alumina,
Examples include solid platinum supported on a carrier such as silica, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and a complex of platinum and vinylsiloxane. This catalyst is finely crushed to improve the dispersibility when it is a solid, and its carrier has a small particle size.
It is preferable to use as a large specific surface area,
Chloroplatinic acid or its complex with an olefin is preferably dissolved in a solvent such as alcohol, ketone, ether or hydrocarbon and used. The compounding amount of the component (D) may be appropriately adjusted so as to obtain a desired curing rate. Generally, the amount of platinum group metal is 1 to 500 ppm with respect to the total amount of the components (A) and (B), and is compatible with siloxane such as chloroplatinic acid from the viewpoint of economical viewpoint and good cured product. The amount of platinum group metal is 1 to 100 ppm with respect to the total amount of the components (A) and (B) described above, and the amount of platinum group metal is 20 to 500 ppm for a solid catalyst such as platinum black. Is preferred.

Examples of the triazole compound as the component (E) of the composition of the present invention include 1,2,3-triazole, 1,2,4-triazole, benzotriazole and derivatives thereof. Examples of derivatives of 1,2,3-triazole include 1-methyl-1,2,3-triazole, 1-phenyl-1,2,3-triazole and 4-methyl-2-phenyl-1,2,3. -Triazole, 1-benzyl-1,2,3-triazole, 4-hydroxy-1,2,3-triazole, 1-amino-1,2,3-triazole, 1-
Benzamido-4-methyl-1,2,3-triazole, 1
-Amino-4,5-diphenyl-1,2,3-triazole,
1,2,3-triazole-4-aldehyde, 4-cyano-
1,2,3-triazole and the like can be mentioned. As the 1,2,4-triazole derivative, 1-methyl-1,2,4-triazole, 1,3-diphenyl-1,2,4-triazole, 5
-Amino-3-methyl-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 1-phenyl-1,
2,4-triazol-5-one, 1-phenylurazole and the like can be mentioned. Examples of the benzotriazole derivative include 1-methylbenzotriazole, 5,6-dimethylbenzotriazole, 2-phenylbenzotriazole, 1-hydroxybenzotriazole, and methyl 1-benzotriazolecarboxylate. Most preferred of these are benzotriazole, 1,2,3-
Triazole and 1-methyl-1,2,3-triazole. These may be used alone or in combination of two or more.

The amount of component (E) blended is usually 0.005 to 1 part by weight, preferably 0.1 part by weight per 100 parts by weight of component (A).
The amount is 01 to 0.3 parts by weight, and even if it is too small, there is no effect, and if it is too large, the curability may decrease. This component (E) contains isopropanol, in order to disperse it uniformly in the composition.
It may be dissolved in an organic solvent such as ethanol, benzene, or toluene to be blended.

To the composition of the present invention comprising the above components (A) to (E), it is preferable to optionally add various fillers as the component (F) for the purpose of improving mechanical strength. . There are no particular restrictions on the type of filler that is the component (F), and any filler that is commonly used in addition-type silicone rubber compositions can be used. For example, fumed silica, precipitated silica, hydrophobized silica, carbon black, titanium dioxide, ferric oxide, aluminum oxide, zinc oxide, quartz powder, diatomaceous earth, calcium silicate, talc, bentonite, asbestos, glass. Fibers, organic fibers, etc. may be mentioned, and these may be used alone or in combination of 2
Combinations of two or more species may also be used. The amount of the filler to be blended is arbitrary as long as the object of the present invention is not impaired,
To 100 parts by weight of the organopolysiloxane (A),
The amount is 500 parts by weight or less, preferably 3 to 500 parts by weight. Of these, fumed silica is preferably used in an amount of 3 to 25 parts by weight per 100 parts by weight of the component (A), and alumina is preferably added in an amount of 300 to 500 parts by weight. The addition amount may be appropriately changed according to the oil absorption amount, surface area, specific gravity and the like.

The composition of the present invention comprises the above (A), (B),
In addition to (C), (D), (E) and the optional component (F), a colorant, a heat resistance improver (red iron oxide, black iron oxide, cerium oxide, etc.), an addition reaction control agent (acetylene), if necessary. System compounds, etc.) may be appropriately blended. Also,
Siloxane or resin structure composed of SiO ₂ units and R ₃ SiO _0.5 Metropolitan as a reinforcing agent, may be added to non-functional silicone oil as a release agent.

The composition of the present invention cures at room temperature or under heating to become an elastic body. The curing method is preferably curing in a dryer or injection molding in a mold.

The composition of the present invention comprises (A), (B),
A mixture of components (D) and preferably (F), (A),
It is often used as a two-component type composed of a mixture of components (C), (E) and preferably (F), but it may be blended as a one-component type by incorporating a reaction control agent.
Examples of the reaction inhibitor include ethynylcyclohexanol and triallyl isocyanurate.

[0024]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In the examples, [parts] indicates parts by weight, and all viscosities indicate values at 25 ° C.

Example 1 100 parts of methyl vinyl silicone oil having both ends blocked with dimethylvinylsiloxy groups, a main chain consisting of dimethylsiloxane units, and a viscosity of 5000 cSt, 1,3,5,7-tetramethyl-1 1.0 part of 3,3,5,7-tetravinylcyclotetrasiloxane, on average:

[0026]

[Chemical 6]

5.0 parts of methylhydrogen polysiloxane represented by the following formula: Hydrophobic surface specific surface area 200 m ² /
g fumed silica 10 parts, chloroplatinic acid 1% isopropyl alcohol solution as platinum content to the compounding amount of methyl vinyl silicone oil 30ppm, benzotriazole 50% ethanol solution 0.03 parts and ethynylcyclohexanol 0.05 as a reaction control agent. Was added to prepare an addition type silicone rubber composition (I).

The resulting composition (I) was press-molded at 170 ° C. for 10 minutes to prepare a plurality of test pieces for measuring compression set in accordance with JIS K6301, which were divided into two groups, one of which was 20
Two types of samples were prepared by performing after-curing at 0 ° C. for 2 hours and not after-curing the other. Each of the two types of test pieces obtained was subjected to a compression set test at 180 ° C. for 22 hours in accordance with JIS K6301.

Further, as in the above, the composition (I) was added to 170
Press-mold at 10 ℃ for 10 minutes to make a 2mm thick sheet,
After after-curing at 200 ℃ for 2 hours, JIS K630
The hardness (JIS A), elongation and tensile strength were measured according to 1. The results are shown in Table 1.

Comparative Example 1 In Example 1, 1,3,5,7-tetramethyl-1,3,5,7
-Preparation of the composition (II) in the same manner as in Example 1 except that the 50% ethanol solution of tetravinylcyclotetrasiloxane and benzotriazole was not used and the compounding amount of methylhydrogenpolysiloxane was changed to 1.7 parts. did.

A test piece was prepared from the obtained composition (II) in the same manner as in Example 1 and the compression set, hardness, elongation and tensile strength were measured. The results are shown in Table 1.

Comparative Example 2 Composition (III) was prepared in the same manner as in Example 1 except that the 50% solution of benzotriazole was not added.
Was prepared.

A test piece was prepared from the obtained composition (III) in the same manner as in Example 1, and the compression set and the hardness, elongation and tensile strength were measured. The results are shown in Table 1.

Comparative Example 3 In Example 1, 1,3,5,7-tetramethyl-1,3,5,7
-Composition (IV) was prepared in the same manner as in Example 1 except that tetravinylcyclotetrasiloxane was not added and the amount of methylhydrogenpolysiloxane was changed to 1.7 parts.

Test pieces were prepared from the obtained composition (IV) in the same manner as in Example 1 and the rubber physical properties and compression set were measured. The results are shown in Table 1.

[0036]

[Table 1]

Example 2 50 parts of methyl vinyl silicone oil having both ends blocked with dimethyl vinyl siloxy groups, a main chain consisting of dimethyl siloxane units, and a viscosity of 5000 cSt, and 50 parts of methyl vinyl silicone oil having a viscosity of 100 000 cSt, 1, 0.35 parts of 3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, on average the formula:

[0038]

[Chemical 7]

[0039] In methylhydrodiene polysiloxane 2.3 parts represented, the ratio of the surface treated hydrophobic surface area 200 m ² /
g fumed silica 10 parts, specific surface area 1 m ² / g wet silica 150 parts, 1% isopropyl alcohol solution of chloroplatinic acid with respect to the total amount of the above two kinds of methyl vinyl silicone oil, 50 ppm as platinum content, An addition type silicone rubber composition (V) was prepared by mixing 0.03 part of a 50% ethanol solution of benzotriazole and 0.05 part of ethynylcyclohexanol as a reaction control agent.

The composition (V) thus obtained was subjected to compression set and hardness according to JIS K-6301 in the same manner as in Example 1.
Elongation and tensile strength were measured. Table 2 shows the results.

Comparative Example 4 In Example 2, 1,3,5,7-tetramethyl-1,3,5,7
Composition (VI) was prepared in the same manner as in Example 2 except that the 50% ethanol solution of tetravinylcyclotetrasiloxane and benzotriazole was not compounded, and the compounding amount of methylhydrogenpolysiloxane was changed to 1.3 parts. .

A cured product was obtained from the obtained composition (VI) in the same manner as in Example 2 and the rubber physical properties and compression set were measured. Table 2 shows the results.

Comparative Example 5 A composition (VII) was prepared in the same manner as in Example 2 except that the 50% solution of benzotriazole was not added.

Test pieces were prepared from the obtained composition (VII) in the same manner as in Example 1, and the physical properties of rubber and compression set were measured. Table 2 shows the results.

Comparative Example 6 In Example 2, 1,3,5,7-tetramethyl-1,3,5,7
-Composition (VIII) was prepared in the same manner as in Example 2 except that tetravinylcyclotetrasiloxane was not added and the amount of methylhydrogenpolysiloxane was changed to 1.3 parts.

Test pieces were prepared from the obtained composition (VIII) in the same manner as in Example 2, and the physical properties of rubber and compression set were measured. Table 2 shows the results.

[0047]

[Table 2]

[0048]

INDUSTRIAL APPLICABILITY The vinyl group-containing organocyclopolysiloxane and the triazole compound used in the composition of the present invention are separately used as a curing inhibitor or a flame retardancy-imparting agent in an addition-curable silicone rubber composition. However, in the present invention, when these are used together for the first time, an unexpected effect that the curing characteristics and the compression set of the cured product are remarkably improved was obtained. As described above, since the curable silicone rubber composition for roll members of the present invention has a small compression set of the cured product, it is suitably used for various rolls such as copying machines and printers.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Kiriki 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Silicon Electronic Materials Research Laboratory

Claims (1)

[Claims] 1. (A) Average composition formula: (R ¹ ) _p SiO _{(4-p) / 2} [wherein R ^{1 s} may be the same or different, and are unsubstituted or substituted monovalent hydrocarbon groups. And p is a number from 1.95 to 2.05] and has two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and has a viscosity at 25 ° C.
100 parts by weight of organopolysiloxane having 200 to 200,000 cSt, (B) General formula: [Wherein R represents a lower alkyl group and n represents an integer of 3 to 8] 0.05 to 5 parts by weight of a vinyl group-containing organocyclopolysiloxane, (C) average composition formula: H _q (R ² ). _r SiO _{(4-qr) / 2} [In the formula, R ² may be the same or different, an alkyl group,
A phenyl group or a trimethylsiloxy group, and q is 0.00
Is an integer of 2 to 1.0, r is a number of 1.0 to 2.0 (wherein q + r is 1.002 to 3.0)], and an organo having two or more hydrogen atoms bonded to a silicon atom in one molecule. Hydrogenene polysiloxane (A) sufficient to provide 0.5 to 5 hydrogen atoms bonded to silicon atoms per one aliphatic unsaturated hydrocarbon group bonded to silicon atoms in component (B) An amount of (D) a platinum group metal-based catalyst (A) and an amount of platinum group metal of 1 to 500 ppm with respect to the total amount of components (B) and (E) a triazole-based compound
A curable silicone rubber composition for roll members, containing 0.005 to 1 part by weight.