US4156709A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing a polypropylene film for shrink packaging
Assignee: Okura Industrial Co Ltd
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Filing: 1977-11-21
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Granted: 1979-05-29
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Expires: 1997-11-21
Abstract
Abstract A film for shrink packaging is prepared by extruding a tubular film made of crystalline polypropylene or crystalline ethylene-propylene copolymer containing up to 10% of ethylene monomer units, and from one to 10% of ethylene-vinylacetate copolymer containing 10 to 50% of vinyl acetate monomer units, and then biaxially stretching the tubular film.
Inventors
- 👤 Kazuo Kondo
- 👤 Toyoki Wano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:19
CPC Classifications
B; B29; B29C; B29C61/00; B29C61/003; B29C48/00; B29C48/001; B29C48/0018; B29C48/03; B29C48/09; B29C48/10; B29C61/06; B29C61/08; B29K; B29K2023/00; B29K2995/00; B29K2995/0037; B29K2995/0041; B29L; B29L2023/00; B29L2023/001
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
119 words
A process for preparing a film for shrink packaging which comprises extruding a tubular film of a film forming composition consisting essentially of A. a crystalline ethylene-propylene copolymer containing 2 to 4% by weight of ethylene monomer units, and B. an ethylene-vinyl acetate copolymer containing from 10 to 50% by weight of vinyl acetate monomer units, wherein the amount of B is from one to 5% by weight, based on the sum of A plus B; cooling the extruded tubular film to solidify same; and then effecting biaxial stretching of said tubular film, at a temperature of from 110° to 130° C., at draw ratios in both the machine and transverse directions in the range of 3.5 to 5.3.
Claim 2
Dependent Claim
119 words
A process for preparing a film for shrink packaging which comprises extruding a tubular film of a film forming composition consisting essentially of A. a crystalline ethylene-propylene copolymer containing 2 to 4% by weight of ethylene monomer units, and B. an ethylene-vinyl acetate copolymer containing from 10 to 50% by weight of vinyl acetate monomer units, wherein the amount of B is from one to 5% by weight, based on the sum of A plus B; cooling the extruded tubular film to solidify same; and then effecting biaxial stretching of said tubular film, at a temperature of from 110° to 130° C., at draw ratios in both the machine and transverse directions in the range of 3.5 to 5.3.
Claim 3
Dependent Claim
28 words
A process as claimed in claim 1 in which the amount of B is from 3 to 5% by weight, based on the sum of A plus B.
Claim 4
Dependent Claim
65 words
A process as claimed in claim 1 in which component B is an ethylene-vinyl acetate copolymer containing 30 to 40% by weight of vinyl acetate monomer units, the amount of B is from 3 to 5% by weight based on the sum of A plus B, the biaxial stretching temperature is from 110° to 120° C. and the draw ratios are from 3.8 to 4.8.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-05-28 | 1982-11-27 | 1983-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-05-28 | 1986-11-27 | 1987-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-05-28 | 1990-11-27 | 1991-05-29 | $7700.00 | Window Closed / Lapsed |