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US5045620A
Expired / Lapsed
US
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Oriented polyethylene film and production thereof
Assignee: Tonen Chemical Corp
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Filing: 1989-09-07
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Granted: 1991-09-03
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Expires: 2009-09-07
Abstract
Abstract Disclosed are oriented polyethylene films having specific elongation and strength, which are excellent in linear tearability and clear tearability, suitably used for packaging and produced by longitudinally stretching a polyethylene resin sheet in which the degree of crosslinking inwardly decreases across the thickness thereof at a draw ratio of at least 5 times at a temperature of not higher than the melting point of a polyethylene resin forming the polyethylene resin sheet, and laterally stretching said sheet 4 to 8 times at a temperature ranging from above the melting point of the polyethylene resin up to 10° C. higher than the melting point thereof.
Inventors
- 👤 Yasushi Itaba
- 👤 Yutaka Yoshifuji
- 👤 Takayoshi Kondo
- 👤 Ichiro Sakamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:04
CPC Classifications
C; C08; C08J; C08J5/00; B; B29; B29C; B29C55/00; B29C55/005; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C55/143; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2105/00; B29K2105/24; B29K2105/243; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
81 words
An oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes, wherein the degree of crosslinking inwardly decreases across the thickness of said film, said film further having a longitudinal elongation of not more than 75% and a lateral elongation of 50 to 300%, said longitudinal elongation being lower than said lateral elongation.
Claim 2
Dependent Claim
81 words
An oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes, wherein the degree of crosslinking inwardly decreases across the thickness of said film, said film further having a longitudinal elongation of not more than 75% and a lateral elongation of 50 to 300%, said longitudinal elongation being lower than said lateral elongation.
Claim 3
Dependent Claim
82 words
An oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes, wherein the degree of crosslinking inwardly decreases across the thickness of said film, said film further having a longitudinal tearing strength of not more than 25 g/mm and a lateral tearing strength, said longitudinal tearing strength being lower than said lateral tearing strength.
Claim 4
Dependent Claim
82 words
An oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes, wherein the degree of crosslinking inwardly decreases across the thickness of said film, said film further having a longitudinal tearing strength of not more than 25 g/mm and a lateral tearing strength, said longitudinal tearing strength being lower than said lateral tearing strength.
Claim 5
Dependent Claim
140 words
A process for producing an oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene comprising the steps of longitudinally stretching a resin sheet of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes in which the degree of crosslinking inwardly decreases across the thickness thereof at a draw ratio of at least 5 times at a temperature of not higher than the melting point of a resin forming the resin sheet, and laterally stretching said sheet at a draw ratio of 4 to 8 times at a temperature ranging from above the melting point of the resin up to 10° C. higher than the melting point thereof.
Claim 6
Dependent Claim
140 words
A process for producing an oriented and differentially crosslinked film of a material selected from the group consisting of polyethylene and copolymers of ethylene comprising the steps of longitudinally stretching a resin sheet of a material selected from the group consisting of polyethylene and copolymers of ethylene having a density of at least 0.935 g/cm 3 and a melt index of at least 0.05 g/10 minutes in which the degree of crosslinking inwardly decreases across the thickness thereof at a draw ratio of at least 5 times at a temperature of not higher than the melting point of a resin forming the resin sheet, and laterally stretching said sheet at a draw ratio of 4 to 8 times at a temperature ranging from above the melting point of the resin up to 10° C. higher than the melting point thereof.
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) | 1994-09-02 | 1995-03-04 | 1995-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-02 | 1999-03-04 | 1999-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-02 | 2003-03-04 | 2003-09-03 | $7700.00 | Window Closed / Lapsed |