US4061704A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tertiary-alkylperoxy alkyl carbonate initiators for hot air vulcanization of silicone rubber
Assignee: PPG Industries Inc
•
Filing: 1975-07-18
•
Granted: 1977-12-06
•
Expires: 1995-07-18
Abstract
Abstract Silicone rubber is vulcanized by heating in the presence of an organic peroxide initiator. Known tertiary-alkylperoxy alkyl carbonates are used in the vulcanization of molded silicone rubber articles, but have not been recommended for use in hot air vulcanization. The tertiary-alkylperoxy alkyl carbonates of the present invention provide good cures with all curing methods, including hot air vulcanization.
Inventors
- 👤 James A. Barter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:13
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/24; C08J3/247; C08K; C08K5/00; C08K5/04; C08K5/14; C08J2383/00; C08J2383/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
181 words
A method of vulcanizing a silicone rubber composition which comprises: a. preparing a heat-vulcanizable composition comprising i. 100 parts of organopolysiloxane polymer gum curable to an elastomeric state and represented by the formula ##STR5## wherein: R is selected independently from the group consisting of monovalent hydrocarbon groups, monovalent halogenated hydrocarbon groups, and monovalent cyanoalkyl groups, and ii. in a minor amount between about 0.1 and 10 parts per 100 parts of organopolysiloxane polymer sufficient to provide complete surface cure, a tertiary-alkylperoxy alkyl carbonate cure initiator represented by the formula ##STR6## wherein: R 1 is a tertiary alkyl group having 4 to 14 carbons and R 2 is an alkyl group having 8 to 26 carbons; b. shaping heat-vulcanizable composition to form an article having a surface; and c. contacting at least a part of the surface of the article with a heated gas for between about 1 and 120 seconds at a temperature above about 315° C. and at about atmospheric pressure or below in order to cure the article to an elastomeric state and to provide a complete surface cure.
Claim 2
Independent Claim
181 words
A method of vulcanizing a silicone rubber composition which comprises: a. preparing a heat-vulcanizable composition comprising i. 100 parts of organopolysiloxane polymer gum curable to an elastomeric state and represented by the formula ##STR5## wherein: R is selected independently from the group consisting of monovalent hydrocarbon groups, monovalent halogenated hydrocarbon groups, and monovalent cyanoalkyl groups, and ii. in a minor amount between about 0.1 and 10 parts per 100 parts of organopolysiloxane polymer sufficient to provide complete surface cure, a tertiary-alkylperoxy alkyl carbonate cure initiator represented by the formula ##STR6## wherein: R 1 is a tertiary alkyl group having 4 to 14 carbons and R 2 is an alkyl group having 8 to 26 carbons; b. shaping heat-vulcanizable composition to form an article having a surface; and c. contacting at least a part of the surface of the article with a heated gas for between about 1 and 120 seconds at a temperature above about 315° C. and at about atmospheric pressure or below in order to cure the article to an elastomeric state and to provide a complete surface cure.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein R 1 and R 2 together have a total of from 16 to 24 carbons.
Claim 4
Dependent Claim
11 words
The method of claim 1 wherein the heated gas is air.
Claim 5
Dependent Claim
11 words
The method of claim 1 wherein the heated gas is steam.
Claim 6
Dependent Claim
26 words
The method of claim 1 which comprises forming the article by continuously extruding heat-vulcanizable composition and continuously passing the extruded article through a hot air oven.
Claim 7
Dependent Claim
16 words
The process of claim 5 wherein the curing temperature is from about 315° to 425° C.
Claim 8
Dependent Claim
13 words
The process of claim 6 wherein the carbonate initiator is tertiary-butylperoxy octadecyl carbonate.
Claim 9
Dependent Claim
13 words
The process of claim 6 wherein the carbonate initiator is tertiary-butylperoxy 2-ethylhexyl carbonate.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein between about 0.05 and 2 percent of the R groups are alkenyl groups.
Claim 11
Dependent Claim
12 words
The method of claim 9, wherein the alkenyl groups are vinyl groups.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-12-05 | 1981-06-06 | 1981-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-05 | 1985-06-06 | 1985-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-05 | 1989-06-06 | 1989-12-06 | $7700.00 | Window Closed / Lapsed |