JPH06172655A - Silicone rubber composition - Google Patents

Abstract

PURPOSE:To provide a silicone rubber composition capable of freely chancing rhov of the silicone rubber while keeping a high stability without having an effect on the fundamental physical properties of the rubber or its workability. CONSTITUTION:An organic peroxide-vulcanized type silicone rubber composition containing an ethylene oxide addition polymer in which the amount of additional ethylene oxide is 5 to 15mol.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicone rubber composition capable of finely adjusting the volume resistivity of a rubber composition, and more specifically, the volume resistivity (hereinafter referred to as “ρ _V ”) originally possessed by silicone rubber. To 10 ¹ [Ω · cm] unit without affecting other properties.

[0002]

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION The category of so-called conductive silicone rubber compositions has been around for a long time, and proposals and commercialization of silicone rubber with various conductivity-imparting substances appropriately selected and blended have been made. But these are ρ _V
10 is ^-3 to 10 ⁸ technique for determining the range of up to ^{[Ω · cm], 10 8} 10 15 [Ω · cm] from [Ω · cm] or more are unique [rho _V silicone or 10 ¹⁶ [Omega・ The technology to determine the range up to cm has not been established. by the way,
In the field of recent OA equipment, with the progress,
Silicone rubbers having various ρ _V have been demanded. In particular, in a toner transfer mechanism used in a PPC (plain paper copying machine) or an LBP (laser printer), a method of applying a voltage to a transfer roll itself made of silicone rubber to perform printing has been widely studied. Therefore, although those [rho _V of silicone rubber was varied 10 ¹ [Ω · cm] units came to be determined, for example, 10 ¹⁴ [Ω ·
cm], 10 ¹³ [Ω · cm], 10 ¹² [Ω · cm], etc. have not been established as a technique for stably supplying the silicone rubber composition. Generally 10 ¹⁵ ~
In order to reduce the ρ _V of 10 ¹⁶ [Ω · cm] by the unit of 10 ¹ [Ω · cm], it is necessary to use a large amount of fillers that give an essentially low ρ _V or to use a group of additives called antistatic agents. Can be considered. However, a silicone polymer having a lower molecular weight than other elastomers is difficult to compound a large amount of a filler, and even if compounded, the compound becomes hard,
Due to this, the deterioration of workability and physical properties cannot be avoided. In addition, a series of additives generally called antistatic agents that are commercially available are roughly classified into an external antistatic agent that is applied on the surface and an internal antistatic agent that is used by mixing (kneading). However, the former external antistatic agent is prone to deterioration due to aging, and it is difficult to say that it is an established technology. On the other hand, the latter anionic / cation / nonionic surfactants, quaternary ammonium salts, etc. used as internal antistatic agents can all be stably compounded in silicone rubber mainly because of the difference in so-called SP value. It was difficult. In view of the drawbacks of the above-mentioned conventional antistatic agents, therefore, as described in Japanese Patent Application Laid-Open No. 3-100058, one in which a fine powder carrying an ethylene oxide adduct as an antistatic agent is blended with silicone rubber. Is proposed. However, the one in which the antistatic agent is supported on the fine powder in this way, that is, the one in which the filler is blended with the silicone rubber, has the drawback that the filler is blended in the silicone rubber as described above. Further, since the addition type silicone rubber is used, there are problems in workability, storage stability, and stability of electrical characteristics of the silicone rubber obtained after curing.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has no influence on the basic physical properties and processability of rubber,
An object of the present invention is to provide a silicone rubber composition capable of freely changing ρ _V of silicone rubber while maintaining high stability.

[0004]

In order to solve the above problems, the present inventor has
As a result of intensive studies, by blending a certain kind of ethylene oxide adduct with the silicone rubber composition, it is possible to arbitrarily change ρ _V while maintaining high stability without affecting the physical properties and processability of the silicone rubber. The inventors have found what can be done and have completed the present invention. That is, the present invention is a silicone rubber composition comprising an organic peroxide vulcanizing type silicone rubber composition containing an ethylene oxide adduct having an ethylene oxide addition amount of 5 to 15 mol.

The silicone rubber composition of the present invention comprises (A) a polyorganosiloxane composition which is crosslinked with an organic peroxide, and (B) an ethylene oxide addition amount of 5 mol or more.
It is a blend of 15 moles of ethylene oxide adduct. The polyorganosiloxane composition as the component (A) is a composition in which the polyorganosiloxane base polymer (a), the curing agent (b), and various additives as necessary are uniformly dispersed. The polyorganosiloxane as the polyorganosiloxane base polymer of the component (a) is a polyorganosiloxane in which at least two of the organic groups bonded to silicon atoms in one molecule are alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl. Organosiloxane is used. Of these organic groups, the vinyl group is particularly preferred because of ease of synthesis, availability of raw materials, and the like. The organic group bonded to a silicon atom other than the above is a monovalent substituted or unsubstituted hydrocarbon group, such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group,
Examples include unsubstituted hydrocarbon groups such as alkyl groups such as dodecyl group, aralkyl groups such as phenyl group, and substituted hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group. . Incidentally, a methyl group is generally used because of its easiness of synthesis. Further, as the curing agent of the component (b), benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-
Butyl peroxide, 2,5-dimethyl-2,5-di-t-
Various organic peroxide vulcanizing agents such as butylperoxyhexane and di-t-butylperoxide are used. Since they give particularly low compression set, dicumyl peroxide,
Cumyl-t-butyl peroxide, 2,5-dimethyl-2,
5-di-t-butylperoxyhexane and di-t-butylperoxide are preferred. In addition, these organic peroxide vulcanizing agents are used as one kind or as a mixture of two or more kinds. The blending amount of the organic peroxide which is the curing agent of the component (b) is preferably 0.05 to 15 parts by weight with respect to 100 parts by weight of the polyorganosiloxane base polymer of the component (a).
If the compounding ratio of the organic peroxide is less than 0.05 part by weight, vulcanization will not be sufficiently carried out, and conversely, if the compounding ratio exceeds 15 parts by weight, no further particular effect will be obtained.

The ethylene oxide adduct as the component (B) is industrially used as a surfactant, and is mainly used as an oil agent for fiber treatment or a solubilizing agent in addition to an emulsifier. Generally, it is liquid at room temperature, but it is also possible to make it solid by manipulating the molecular weight. The specific chemical names are listed below, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene sorbitan monooleate,
Examples thereof include polyoxyethylene sorbitan trioleate, polyoxyethylene glycerin monooleate, and polyoxyethylene glycerin monostearate. Further, in consideration of compatibility with silicone rubber and effective change of ρ _V , the ethylene oxide addition amount of the above ethylene oxide addition needs to be 5 to 15 mol. If it is less than 5 mol, it becomes difficult to change ρ _V ,
If the amount exceeds 15 mol, migration and physical properties may be affected depending on the blending with silicone. The type does not matter as long as this condition is satisfied. The blending amount is (a) 100 polyorganosiloxane base polymer.
It is preferably 0.1 to 10 parts by weight with respect to parts by weight. The kneading method is not particularly limited as long as each constituent component is dispersed in the compound.

A filler, a pigment, a heat resistance improver, a flame retardant, etc. may be optionally added to the silicone rubber composition of the present invention, as long as the effect of the present invention is not impaired. You may use together polyorganosiloxane. Examples of such substances are usually fumed silica, precipitated silica, reinforcing filler such as diatomaceous earth, titanium oxide, aluminum oxide, zinc oxide, iron oxide, cerium oxide, mica, clay, zinc carbonate, carbonic acid. Examples include manganese, cerium hydroxide, glass beads, polydimethylsiloxane, alkenyl group-containing polysiloxane, and the like.

[0008]

EXAMPLES Next, the present invention will be described in more detail by way of examples. In the examples, “parts” means parts by weight unless otherwise specified. Example 1 100 parts by weight of polydimethylsiloxane (polymerization degree 6000) containing 0.2 mol% of methylvinylsiloxane unit as a siloxane base polymer, silica powder (Aerosil 13
0 (manufactured by Nippon Aerosil Co., Ltd.)) and 1 part by weight of "Rikemal A-20" polyoxyethylene alkylphenyl ether (addition amount of ethylene oxide 5 mol) (manufactured by Riken Vitamin Co., Ltd.) as an ethylene oxide adduct. Parts and 1 part by weight of 2,5-dimethyl-2,5-di-t-butylperoxyhexane as a curing agent were mixed and kneaded to prepare a compound. Next, using this compound, a sample sheet having a thickness of 1 mm was prepared, and the volume resistivity of the prepared sample sheet was measured to evaluate the conductivity. This sample sheet was prepared by press-vulcanizing at 170 ° C. for 10 minutes after forming the sheet and then performing hot air vulcanization at 200 ° C. for 4 hours as secondary vulcanization. The volume resistivity ρ _V was measured at an applied voltage of 500 V in accordance with JIS K-6911 “General test method for thermosetting plastics”.
Further, the tensile strength (TB) and the elongation (EB) were measured by JIS K-6301 "Vulcanized rubber physical test method". In addition, TB,
EB was measured using a 2 mm sheet. The results are shown in Table 1.

Example 2 The above example except that the silica powder was compounded in an amount of 20 parts by weight and 20 parts by weight of a conductive carbon black (Denka Black Granules: manufactured by Denki Kagaku Kogyo) was added as a new component. The same operation as in 1 was performed to obtain a compound, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Example 3 A compound was obtained by the same procedure as in Example 1 except that the compounding amount of the ethylene oxide adduct was 5 parts by weight, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 1 A compound was obtained by performing the same operation as in Example 1 except that the ethylene oxide adduct was not added, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 2 In place of the ethylene oxide adduct, 1 part by weight of a surfactant type antistatic agent (“Electrostopper K” alkylphosphoric acid potassium salt; manufactured by Kao Corporation), which is a general-purpose antistatic agent, was blended. Other than that, the same operation as in Example 1 was performed to obtain a compound, and the same evaluation as in Example 1 was performed.
The results are shown in Table 1.

Comparative Example 3 A compound was obtained and evaluated by the same procedure as in Example 2 except that the ethylene oxide adduct was not added. The results are shown in Table 1.

Comparative Example 4 A compound was obtained by the same procedure as in Example 1 except that the ethylene oxide adduct was polyoxyethylene alkyl ether having an ethylene oxide addition amount of 4 mol, and the same evaluation as in Example 1 was performed. I went. The results are shown in Table 1.

Comparative Example 5 A compound was obtained in the same manner as in Example 1 except that the ethylene oxide adduct was polyoxyethylene glycerin monooleate having an ethylene oxide addition amount of 16 mol. An evaluation was made. The results are shown in Table 1.
Shown in.

[0016]

[Table 1]

As is clear from Table 1 above, the silicone rubber compositions (Examples 1 to 3) of the present invention in which the ethylene oxide adduct is blended do not affect the physical properties of the rubber and are insulating. It was possible to reduce the ρ _V regardless of whether the filler is a conductive filler or a conductive filler (carbon black). Compared with the silicone composition of the present invention, when a known antistatic agent is used, not only the effect of lowering its ρ _V cannot be obtained, but also the physical properties are adversely affected, and it cannot be put to practical use at all. There wasn't.
In addition, even if the amount of ethylene oxide added was 4 mol, ρ _V did not decrease, and the amount of ethylene oxide added was
When 16 mol was blended, the amount of ethylene oxide added bleeded out due to the heat history during the secondary vulcanization, and no decrease in ρ _V was observed.

Claims (1)

[Claims] 1. An organic peroxide vulcanizing type silicone rubber composition, wherein the ethylene oxide addition amount is from 5 mol to 15 mol.
A silicone rubber composition comprising a molar amount of an ethylene oxide adduct.