EP0069495A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Heat-shrinkable thermoplastic packaging film and receptacles formed therefrom
Assignee: WR Grace and Co
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Filing: 1982-06-18
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Granted: —
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Expires: 2002-06-18
Abstract
Abstract The invention provides a multi-layer, heat-shrinkable, thermoplastic packaging film which can be heat-sealed to itself to provide strong seals at pasteurizing temperatures. The preferred film has four layers including, in order, a sealing surface layer comprising a blend of propylene-ethylene copolymer and (butene-1)-ethylene copolymer, a layer comprising ethylene-vinyl acetate copolymer which may be cross-linked to further increase high temperature strength of the film as desired; a relatively gas-impermeable layer comprising a copolymer of vinylidene chloride; and a surface layer of the same blend as the sealing layer. Receptacles such as end seal and side seal bags can be made from the film at a faster rate than with prior art films and these receptacles have the high temperature seal qualities of propylene polymers and the hot water shrink capabilities of ethylene polymers.
Inventors
- 👤 Norman D. Bornstein
- 👤 Johnnie J. Walters
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 17:24
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/06; B32B27/08; B32B27/16; B32B27/30; B32B27/304; B32B27/306; B32B27/32; B32B38/00; B32B38/0012; B32B2307/00; B32B2307/30; B32B2307/31; B32B2307/70; B32B2307/732; B32B2307/734; B32B2307/736; B32B2323/00; B32B2323/10; B32B2439/00; B32B2439/70; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/13; Y10T428/1324; Y10T428/1328; Y10T428/28; Y10T428/2813; Y10T428/2817; Y10T428/2826; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/3192; Y10T428/31928; Y10T428/31935
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
90 words
A multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat seals having improved seal strength at elevated temperatures comprising: a) a first or surface sealing layer comprising a blend of (i) a propylene homopolymer or copolymer and (ii) a butene-1 homopolymer or copolymer; b) a second layer comprising an ethylene homopolymer or copolymer, c) a third or low gas transmission layer comprising a vinylidene chloride copolymer or a hydrolysed ethylene-vinyl acetate copolymer; and, d) a fourth or outer surface layer comprising a blend as specified for the first layer.
Claim 2
Dependent Claim
90 words
A multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat seals having improved seal strength at elevated temperatures comprising: a) a first or surface sealing layer comprising a blend of (i) a propylene homopolymer or copolymer and (ii) a butene-1 homopolymer or copolymer; b) a second layer comprising an ethylene homopolymer or copolymer, c) a third or low gas transmission layer comprising a vinylidene chloride copolymer or a hydrolysed ethylene-vinyl acetate copolymer; and, d) a fourth or outer surface layer comprising a blend as specified for the first layer.
Claim 3
Dependent Claim
57 words
A film according to claim 1 wherein the blend for the first and fourth layers is a blend of (i) 90% to 40% by weight of a propylene-ethylene copolymer having 1.5% to 4.0% ethylene and (ii) 10% to 60% by weight of a butene-1 homopolymer or a (butene-l)-ethylene copolymer having up to 6.0% by weight of ethylene.
Claim 4
Dependent Claim
26 words
A film according to claim 1 or 2 wherein the second layer comprises an ethylene-vinyl acetate copolymer having 3% to 12% vinyl acetate content by weight.
Claim 5
Dependent Claim
14 words
A film according to claim 1 or 2 wherein the second layer comprises polyethylene.
Claim 6
Dependent Claim
23 words
A film according to claim 3 wherein the first and second layers have been irradiated to a dosage of at least 2 MR.
Claim 7
Dependent Claim
39 words
A film according to claim 3 wherein the ethylene-vinyl acetate copolymer comprises about 6% vinyl acetate by weight and the copolymer has been cross-linked to the equivalent of a dosage level in the range of 2 to 6 MR.
Claim 8
Dependent Claim
31 words
A film according to any of claims 1 to 6 which has been stretch oriented and has a thickness in the range of 1.0 to 4.0 mils (0.025 to 0.1 mm.).
Claim 9
Dependent Claim
53 words
A process for making a multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat seals having improved seal strength at elevated temperatures which comprises: a) coextruding first and second polymeric layers, as defined in claim 1, and b) irradiating the said coextruded layers to a dosage level of at least 2 MR.
Claim 10
Dependent Claim
16 words
A process according to claim 8 wherein the multi-layer film is stretched to orient the same.
Claim 11
Dependent Claim
44 words
A process according to claim 8 or 9 wherein the first layer comprises a blend of 90% to 40% by weight propylene-ethylene copolymer with 10% to 60% by weight of (butene-l)-ethylene copolymer or butene-1 homopolymer and the second layer comprises an ethylene-vinyl acetate copolymer.
Claim 12
Dependent Claim
29 words
A process according to claim 8, 9 or 10 including the step of joining at least one additional polymeric layer to the second layer after irradiation has been completed.
Claim 13
Dependent Claim
32 words
A process according to claim 11 including the step of extrusion coating a third layer onto the second, said third layer comprising a vinylidene chloride copolymer or a hydrolysed ethylene-vinyl acetate copolymer.
Claim 14
Dependent Claim
29 words
A process according to claim 12 including the step of coating a fourth layer onto the third, said fourth layer comprising a blend as specified for the first layer.
Claim 15
Dependent Claim
22 words
A receptacle formed by heat sealing together selected surface areas of a film as claimed in any of claims 1 to 7.
Claim 16
Dependent Claim
26 words
A receptacle formed by heat sealing together selected surface areas of a film produced by a process as defined in any of claims 8 to 13.
Claim 17
Dependent Claim
44 words
A receptacle as claimed in claim 14 or 15 in the form of a casing formed by heat sealing together two opposed edges of a sheet of a said film to form a tube and thereafter gathering and closing one end of said tube.
References Cited (Backward Citations)
No citation records indexed.
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