US4649009A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing a heat-shrinkable polypropylene film
Assignee: Mitsubishi Chemical Corp
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Filing: 1985-08-07
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Granted: 1987-03-10
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Expires: 2005-08-07
Abstract
Abstract A process for producing a heat-shrinkable polypropylene film, which comprises stretching a film of a polypropylene resin firstly in one direction, then heat-treating it, and further stretching it in a direction perpendicular to the direction of the first stretching.
Inventors
- 👤 Kizo Shibata
- 👤 Kazuo Dodo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:50
CPC Classifications
B; B29; B29C; B29C61/00; B29C61/06; B29C55/00; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C55/143; B29K; B29K2023/00; B29K2023/10; B29K2023/12; B29L; B29L2007/00; B29L2007/008
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
111 words
A process for producing a heat-shrinkable polypropylene film having balanced physical strength in both the longitudinal and transverse directions and having substantial heat shrinkability only in one direction, which comprises stretching a film of a polypropylene resin firstly in one direction, then heat-treating it at a temperature within a range of less than the melting point of the resin and not less than 30° C. below the melting point of the resin, and higher than the temperature for the first stretching, and further stretching it in a direction perpendicular to the direction of the first stretching at a temperature lower than the temperature for the heat-treatment by at least 10° C.
Claim 2
Dependent Claim
111 words
A process for producing a heat-shrinkable polypropylene film having balanced physical strength in both the longitudinal and transverse directions and having substantial heat shrinkability only in one direction, which comprises stretching a film of a polypropylene resin firstly in one direction, then heat-treating it at a temperature within a range of less than the melting point of the resin and not less than 30° C. below the melting point of the resin, and higher than the temperature for the first stretching, and further stretching it in a direction perpendicular to the direction of the first stretching at a temperature lower than the temperature for the heat-treatment by at least 10° C.
Claim 3
Dependent Claim
20 words
The process according to claim 1, wherein the polypropylene resin has heat of crystallization of from 7 to 15 cal/g.
Claim 4
Dependent Claim
32 words
The process according to claim 2 wherein the polypropylene resin comprises from 50 to 90% by weight of a propylene polymer and from 10 to 50% by weight of a petroleum resin.
Claim 5
Dependent Claim
22 words
The process according to claim 1, wherein the first stretching is conducted at a stretching ratio of from 2 to 10 times.
Claim 6
Dependent Claim
18 words
The process according to claim 1, wherein the heat treatment is conducted for from 2 to 180 seconds.
Claim 7
Dependent Claim
42 words
The process according to claim 1, wherein the further stretching is conducted at a temperature within a range of from 10° to 60° C. below the melting point of the resin and at a stretching rate of from 1.5 to 7 times.
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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) | 1990-03-09 | 1990-09-08 | 1991-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-09 | 1994-09-08 | 1995-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-09 | 1998-09-08 | 1999-03-10 | $7700.00 | Window Closed / Lapsed |