Patent US4600144A successfully refreshed from Google Patents.
Patent US4048275A successfully refreshed from Google Patents.
US4048275A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cross-linking and foaming injection molding process for ethylenic polymers
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1975-10-30
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Granted: 1977-09-13
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Expires: 1995-10-30
Abstract
Abstract An injection molding process for forming cross-linked, foamed moldings of an ethylenic polymer by passing a molding composition comprising an ethylenic polymer/cross-linking agent/foaming agent blend through the cylinder of an injection molding machine without substantially decomposing the cross-linking agent and the foaming agent, introducing the molding composition into a molding composition holding chamber provided at the exit end of the cylinder of the injection molding machine to decompose the cross-linking agent and the foaming agent therein, and injecting the molding composition into a mold. The invention also provides apparatus for carrying out the process comprising an injection molding cylinder for conveying and plasticizing the molding composition and a molding composition holding chamber provided at the exit end of the cylinder.
Inventors
- 👤 Teruyoshi Usamoto
- 👤 Kenji Miyawaki
- 👤 Toshiaki Shiota
- 👤 Hideki Takeuchi
- 👤 Yoshio Tadokoro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:43
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/38; B29C44/42; Y; Y10; Y10S; Y10S264/00; Y10S264/05; Y10S264/18; Y10S264/83
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
109 words
A process for injection molding a cross-linked foamed ethylenic polymer article, which comprises plasticizing a molding composition comprising an ethylenic polymer, a cross-linking agent, and a foaming agent without substantially decomposing the cross-linking agent and the foaming agent, transporting said plasticized composition to a holding chamber, holding and heating said molding composition temperature and time sufficient to decompose the cross-linking agent and the foaming agent in said holding chamber while maintaining sufficient pressure on said composition to prevent foaming thereof and to thereby cross-link said ethylenic polymer to a gel percentage of less than about 40%, and then injecting said molding composition into a mold to form said article.
Claim 2
Dependent Claim
109 words
A process for injection molding a cross-linked foamed ethylenic polymer article, which comprises plasticizing a molding composition comprising an ethylenic polymer, a cross-linking agent, and a foaming agent without substantially decomposing the cross-linking agent and the foaming agent, transporting said plasticized composition to a holding chamber, holding and heating said molding composition temperature and time sufficient to decompose the cross-linking agent and the foaming agent in said holding chamber while maintaining sufficient pressure on said composition to prevent foaming thereof and to thereby cross-link said ethylenic polymer to a gel percentage of less than about 40%, and then injecting said molding composition into a mold to form said article.
Claim 3
Dependent Claim
61 words
The process according to claim 1, wherein the temperature of said plasticizing is below the sum of the one minute half-life temperature of the cross-linking agent plus 20° C, and the temperature of holding is kept at a temperature above the temperature of the plasticization to the sum of the one minute half-life temperature of the cross-linking agent plus 70° C.
Claim 4
Dependent Claim
43 words
The process according to claim 1, wherein the molding composition is a mixture comprising 100 parts by weight of the ethylenic polymer, 0.05 - 30 parts by weight of the foaming agent and 0.05 - 10 parts by weight of the cross-linking agent.
Claim 5
Dependent Claim
42 words
The process according to claim 1, wherein the ethylenic polymer is a homopolymer of ethylene, a copolymer of ethylene and one or more comonomers, mixtures of two or more thereof or mixtures of two or more thereof and another polymer miscible therewith.
Claim 6
Dependent Claim
16 words
The process according to claim 4, wherein the copolymer of ethylene is an ethylene-vinyl acetate copolymer.
Claim 7
Dependent Claim
18 words
The process according to claim 1, wherein the cross-linking agent is 1,3-di-(t-butyl-peroxy-isopropyl)benzene, benzoyl peroxide, dicumyl peroxide or 1,1-di-t-butyl-peroxy-3,3,5-trimethylcyclohexane.
Claim 8
Dependent Claim
18 words
The process according to claim 1, wherein the foaming agent is azodicarbonamide, p-toluenesulfonyl hydrazide, azobis-isobutyronitrile, or dinitrosopentamethylene tetramine.
Claim 9
Dependent Claim
25 words
The process according to claim 1, wherein the gel percentage of said molding composition after holding is greater than 30% but less than about 40%.
References Cited (Backward Citations)
CA696222A
Cited
US2530289A
Cited
US3098832A
Cited
US3376238A
Cited
US3608145A
Cited
US3923922A
Cited
US3878285A
Cited
US3776989A
Cited
US3937447A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-12 | 1981-03-14 | 1981-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-12 | 1985-03-14 | 1985-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-12 | 1989-03-14 | 1989-09-13 | $7700.00 | Window Closed / Lapsed |