US4460631A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sealable, biaxially stretched polypropylene film having high scratch resistance, and process for its manufacture
Assignee: Hoechst AG
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Filing: 1981-10-28
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Granted: 1984-07-17
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Expires: 2001-10-28
Abstract
Abstract Disclosed is a sealable, biaxially stretched polyethylene-coated polypropylene film, preferably manufactured as a flat film, which is not only extremely scratch-resistant but is also rapidly sealable, with good machine-running characteristics and high transparency. The polyethylene sealing layer has a scratch resistance of ≦50% gloss reduction, relative to an initial gloss of 100%, measured according to ASTM Standard Specification D673-70 (1976), and a density of ≧0.94 g/cm 3 , preferably of ≧0.95 g/cm 3 . Also disclosed is a process for the manufacture of the film, and the use of the film as an abrasion-resistant packaging material.
Inventors
- 👤 Gerhard Stegmeier
- 👤 Siegfried Janocha
- 👤 Hartmut Hensel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:30
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/06; B32B27/08; B32B27/18; B32B27/32; B32B2307/00; B32B2307/30; B32B2307/31; B32B2307/50; B32B2307/514; B32B2307/518; B32B2323/00; B32B2323/04; B32B2439/00; B32B2439/70; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/266; Y10T428/28; Y10T428/2813; Y10T428/2817; Y10T428/2826; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
177 words
A sealable biaxially stretched composite polypropylene film, comprising: a substrate layer comprising polypropylene; and at least one heat-sealable ethylene polymer layer comprising an ethylene polymer applied to at least one side of said polypropylene layer and having a scratch resistance of ≦ about 50% gloss reduction, relative to an initial gloss of 100%, measured according to ASTM standard specification D673-70 and a density of ≧about 0.95 g/cm 3 , wherein said ethylene polymer comprises polyethylene or a copolymer of ethylene and a minor amount of a comonomer which is copolymerizable with said ethylene, prepared by a process comprising the steps of: providing said polypropylene substrate layer; coating said polypropylene substrate layer with at least one of said ethylene polymer layers in a heated condition and thereby bonding said ethylene polymer layer to said polypropylene layer to form a film; immediately chilling said hot ethylene polymer layer of said film to a first temperature of less than or equal to about 70° C.; and subsequently stretching the composite film at a second temperature higher than said first temperature.
Claim 2
Dependent Claim
177 words
A sealable biaxially stretched composite polypropylene film, comprising: a substrate layer comprising polypropylene; and at least one heat-sealable ethylene polymer layer comprising an ethylene polymer applied to at least one side of said polypropylene layer and having a scratch resistance of ≦ about 50% gloss reduction, relative to an initial gloss of 100%, measured according to ASTM standard specification D673-70 and a density of ≧about 0.95 g/cm 3 , wherein said ethylene polymer comprises polyethylene or a copolymer of ethylene and a minor amount of a comonomer which is copolymerizable with said ethylene, prepared by a process comprising the steps of: providing said polypropylene substrate layer; coating said polypropylene substrate layer with at least one of said ethylene polymer layers in a heated condition and thereby bonding said ethylene polymer layer to said polypropylene layer to form a film; immediately chilling said hot ethylene polymer layer of said film to a first temperature of less than or equal to about 70° C.; and subsequently stretching the composite film at a second temperature higher than said first temperature.
Claim 3
Dependent Claim
26 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said scratch resistance of said ethylene polymer layer comprises ≦ about 40% gloss reduction.
Claim 4
Dependent Claim
23 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein the film has a seal strength of ≧ about 0.4N/15 mm.
Claim 5
Dependent Claim
24 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein the thickness of said ethylene polymer layer comprises ≦ about 2 μm.
Claim 6
Dependent Claim
19 words
A sealable, biaxially stretched polpropylene film as defined in claim 4, wherein said thickness comprises ≦ about 1 μm.
Claim 7
Dependent Claim
20 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said polypropylene layer contains at least one additive.
Claim 8
Dependent Claim
21 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said ethylene polymer layer contains at least one additive.
Claim 9
Dependent Claim
25 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said polypropylene and said ethylene polymer layers each contain at least one additive.
Claim 10
Dependent Claim
32 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said polypropylene comprises a copolymer of propylene and a minor amount of a comonomer which is copolymerizable with the propylene.
Claim 11
Dependent Claim
36 words
A sealable, biaxially stretched polypropylene film as defined in claim 1 or claim 9, wherein said ethylene polymer comprises a copolymer of ethylene and a minor amount of a comonomer which is copolymerizable with the ethylene.
Claim 12
Dependent Claim
24 words
A sealable, biaxially stretched polypropylene film as defined in claim 9, wherein said comonomers are present in an amount of less than about 20%.
Claim 13
Dependent Claim
24 words
A sealable, biaxially stretched polypropylene film as defined in claim 11, wherein said comonomers are present in an amount of less than about 10%.
Claim 14
Dependent Claim
19 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein all of the layers are biaxially oriented.
Claim 15
Dependent Claim
25 words
A sealable, biaxially stretched polypropylene film as defined in claim 1, wherein said polypropylene layer is relatively thick in comparison to said ethylene polymer layer.
Claim 16
Dependent Claim
34 words
A sealable, biaxially stretched polypropylene film as defined in claim 14, wherein the thickness of said polypropylene layer is about 35 μm and the thickness of said ethylene polymer is ≦ about 2 μm.
Claim 17
Dependent Claim
34 words
A sealable, biaxially stretched polypropylene film as defined in claim 15, wherein the thickness of said polypropylene layer is about 35 μm and the thickness of said ethylene polymer is ≦ about 1 μm.
Claim 18
Dependent Claim
98 words
A process for preparing sealable, biaxially stretched polypropyene film according to claim 1, comprising the steps of: providing said polypropylene substrate layer; coating said polypropylene substrate layer with at least one of said ehtylene polymer layers in a heated condition and thereby bonding said ethylene polymer layer to said polypropylene layer to form a film; biaxially stretching said film; and immediately chilling said hot ethylene polymer layer of said film to a first temperature of less than or equal to about 70° C.; and subsequently stretching the composite film at a second temperature higher than said first temperature.
Claim 19
Dependent Claim
25 words
A process for preparing sealable, biaxially stretched polypropylene film as described in claim 17, wherein said ehtylene polymer layer is co-extruded with said polypropylene layer.
Claim 20
Dependent Claim
34 words
A process for preparing sealable, biaxially stretched polypropylene film as described in claim 17, wherein said ethylene polymer layer is applied subsequent to longitudinal stretching and prior to lateral stretching of said polypropylene layer.
Claim 21
Dependent Claim
25 words
A process for preparing sealable, biaxially stretched polypropylene film as described in claim 17, wherein said ethylene polymer layer is chilled by a gas jet.
Claim 22
Dependent Claim
25 words
A process for preparing sealable, biaxially stretched polypropylene film as described in claim 17, wherein said ethylene polymer layer is chilled by a cooling bath.
Claim 23
Dependent Claim
14 words
A process as defined in claim 17, wherein all the layers are biaxially oriented.
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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) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |