Claims
- 1. A method of preparing a silicone sponge roll comprising a roll body having a metal core or a metal core and a rubber sleeve, and a silicone rubber layer formed on the outer surface of the roll body, the method comprising the steps of:
- mixing uniformly a foamable silicone composition comprising
- (A) 100 parts by weight of an organopolysiloxane free of an aliphatic unsaturated group, the organopolysiloxane being represented by Formula (I)
- R.sub.4 SiO.sub.(4-a)/2 (I)
- wherein R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms or a hydroxyl group, and the letter a is a positive number in the range of from 1.95 to 2.05,
- (B) 3 to 100 parts by weight of a finely divided silica filler,
- (C) 0.1 to 10 parts by weight of an azodicarbonamide foaming agent having a decomposition temperature of 100.degree. to 160.degree. C., and
- (D) 0.1 to 10 parts by weight of a diacyl peroxide having a decomposition temperature of 30.degree. to 100.degree. C. to provide a half-life of about 10 hours, the diacyl peroxide being selected from the group consisting of benzoyl peroxide, di(2,4-dichlorobenzoyl)peroxide, di(p-chlorobenzoyl)peroxide, di(o-chlorobenzoyl)-peroxide, di(p-methylbenzoyl)peroxide, di(o-methylbenzoyl)peroxide, di(p-bromobenzoyl)peroxide, di(o-bromobenzoyl)peroxide, di(2,4-dimethylbenzoyl)-peroxide, di(p-trimethylsilybenzoyl)peroxide, and mixtures thereof,
- extruding the silicone composition through an extruder onto the roll body to form a layer; and
- foaming and vulcanizing the extruded product at a temperature of 150.degree. to 300.degree. C. at atmospheric pressure for 10 seconds to 30 minutes to form the silicone sponge rubber layer on the outer surface of the roll body.
- 2. The method of claim 1, wherein the Formula (I) organopolysiloxane of component (A) has a viscosity of at least 100,000 centistokes at 25.degree. C.
- 3. The method of claim 1, wherein the majority of R in Formula (I) are monovalent hydrocarbon groups.
- 4. The method of claim 1, wherein R in Formula (I) is a halogen substituted monovalent hydrocarbon.
- 5. The method of claim 3, wherein R in Formula (I) is a monovalent alkyl group or a monovalent aryl group.
- 6. The method of claim 1, wherein the majority of R in Formula (I) are methyl groups.
- 7. The method of claim 1, wherein the component (B) finely divided silica filler has a surface area of at least 1m.sup.2 /g.
- 8. The method of claim 1, wherein the component (B) finely divided silica filler is selected from the group consisting of:
- fumed silica, wet silica, quartz powder, and diatomaceous earth.
- 9. The method of claim 1, wherein the component (C) is azodicarbonamide in admixture with at least one member selected from the group consisting of urea, a urea compound, zinc oxide, stearic acid, and zinc stearate.
- 10. The method of claim 1, further comprising a post curing step of heating the prepared sponge roll at 150.degree.-220.degree. C. for up to 8 hours.
- 11. The method of claim 1, further comprising the step of coating on a surface of the prepared sponge roll a perfluoroalkylene resin, a polytetrafluoroethylene resin, a room tempeature vulcanizable silicone fluid or a low temperature vulcanizable silicone fluid.
Priority Claims (1)
Number |
Date |
Country |
Kind |
1-132299 |
May 1989 |
JPX |
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Parent Case Info
This application is a divisional of copending application Ser. No. 07/527,359 filed on May 23, 1990.
US Referenced Citations (5)
Foreign Referenced Citations (3)
Number |
Date |
Country |
2546698 |
Jan 1977 |
DEX |
487969 |
May 1970 |
CHX |
1130674 |
Oct 1968 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
527359 |
May 1990 |
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