US5055328A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differentially cross-linked multilayer film
Assignee: Viskase Corp
•
Filing: 1989-06-16
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Granted: 1991-10-08
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Expires: 2009-06-16
Abstract
Abstract A tubular article formed of multilayer differentially cross-linked heat sealable film suitable for the manufacture of bags used in the packaging of meats. The multilayer film contains at least two layers the inner of which is a heat sealable layer containing an antioxidant cross-linking inhibitor in an amount sufficient to inhibit the cross-linking of that layer by irradiation. Accordingly, upon exposure of the multilayer film to radiation, the outer layer will be cross-linked to a greater extent than the first heat sealable layer.
Inventors
- 👤 Charles P. Evert
- 👤 John Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:57
CPC Classifications
B; B32; B32B; B32B7/00; B32B7/02; B32B1/00; B32B1/08; B32B27/00; B32B27/06; B32B27/08; B32B27/16; B32B27/18; B32B27/30; B32B27/306; B65; B65D; B65D75/00; B32B2307/00; B32B2307/50; B32B2307/514; B32B2307/518; B32B2307/70; B32B2307/724; B32B2307/7242; B32B2307/7244; B32B2307/732; B32B2307/734; B32B2307/736; B32B2331/00; B32B2331/04; B32B2439/00; B32B2439/70; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/1328; Y10T428/1334; Y10T428/1341; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/3192; Y10T428/31928
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
88 words
A tubular article formed of biaxially oriented, differentially cross-linked, heat shrinkable multilayer film irradiated to at least about 2 MR comprising a thermoplastic inner layer and a thermoplastic outer layer, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.5 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 2
Dependent Claim
88 words
A tubular article formed of biaxially oriented, differentially cross-linked, heat shrinkable multilayer film irradiated to at least about 2 MR comprising a thermoplastic inner layer and a thermoplastic outer layer, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.5 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 3
Dependent Claim
17 words
A tubular article according to claim 1 wherein said inner and outer irradiated layers are adhered together.
Claim 4
Dependent Claim
21 words
A tubular article according to claim 1 wherein said inner and outer irradiated layers are separated by an oxygen barrier layer.
Claim 5
Dependent Claim
104 words
A tubular article formed of biaxially oriented, differentially cross-linked heat shrinkable multilayer film irradiated to at least about 2 MR comprising a thermoplastic inner layer, a thermoplastic outer layer and an oxygen barrier layer between said inner and outer layers and adhered thereto on opposite sides, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.7 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 6
Dependent Claim
104 words
A tubular article formed of biaxially oriented, differentially cross-linked heat shrinkable multilayer film irradiated to at least about 2 MR comprising a thermoplastic inner layer, a thermoplastic outer layer and an oxygen barrier layer between said inner and outer layers and adhered thereto on opposite sides, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.7 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 7
Dependent Claim
28 words
A tubular article according to claim 4 wherein the ratio of said melt flow indices of the inner layer to the outer layer is at least about 4.
Claim 8
Dependent Claim
15 words
A tubular article according to claim 4 wherein the outer layer contains a cross-linking enhancer.
Claim 9
Dependent Claim
21 words
A tubular article according to claim 4 wherein said film is irradiated at between about 3 MR and about 5 MR.
Claim 10
Dependent Claim
26 words
A tubular article according to claim 4 wherein said antioxidant is selected from the group consisting of 2.6 ditert butyl-4-ethyl phenol (BHEB) and butylated hydroxytoluene (BHT).
Claim 11
Dependent Claim
26 words
A tubular article according to claim 4 wherein said antioxidant in said irradiated inner layer provides BHT Equivalency of between about 500 and about 2000 ppm.
Claim 12
Dependent Claim
25 words
A tubular article according to claim 4 wherein the major constituent of at least one of said inner and outer layers is ethylene vinyl acetate.
Claim 13
Dependent Claim
21 words
A tubular article according to claim 4 wherein the major constituent of said inner and outer layers is ethylene vinyl acetate.
Claim 14
Dependent Claim
31 words
A tubular article according to claim 4 wherein said inner and outer layers are formed of at least one member selected from the group consisting of polyethylene and ethylene vinyl acetate.
Claim 15
Dependent Claim
30 words
A tubular article according to claim 4 wherein said oxygen barrier layer is a member selected from the group consisting of a vinylidene chloride copolymer, ethylene vinyl alcohol and polyamide.
Claim 16
Independent Claim
123 words
A method of manufacturing a tubular article formed of biaxially oriented differentially cross-linked, heat shrinkable multilayer film comprising the steps of: a) forming a tube of blown multilayer film comprising a thermoplastic inner layer and a thermoplastic outer layer with the inner layer containing an antioxidant; b) biaxially orienting said multilayer film to make same heat shrinkable; and c) irradiating the biaxially oriented heat shrinkable film at dosage of at least about 2 MR to simultaneously adjust the inner layer melt flow index to at least about 0.5 and adjust the outer layer melt flow index to less than about 0.7 such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 17
Independent Claim
123 words
A method of manufacturing a tubular article formed of biaxially oriented differentially cross-linked, heat shrinkable multilayer film comprising the steps of: a) forming a tube of blown multilayer film comprising a thermoplastic inner layer and a thermoplastic outer layer with the inner layer containing an antioxidant; b) biaxially orienting said multilayer film to make same heat shrinkable; and c) irradiating the biaxially oriented heat shrinkable film at dosage of at least about 2 MR to simultaneously adjust the inner layer melt flow index to at least about 0.5 and adjust the outer layer melt flow index to less than about 0.7 such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5.
Claim 18
Dependent Claim
15 words
A method according to claim 14 wherein said inner and outer layers are adhered together.
Claim 19
Dependent Claim
26 words
A method according to claim 14 wherein said inner and outer layers are separated by an oxygen barrier layer and adhered thereto on opposite sides thereof.
Claim 20
Dependent Claim
27 words
A method according to claim 16 wherein the ratio of said melt flow indices of the inner layer to the outer layer is at least about 4.
Claim 21
Dependent Claim
14 words
A method according to claim 16 wherein the outer layer contains a cross-linking enhancer.
Claim 22
Dependent Claim
20 words
A method according to claim 16 wherein said film is irradiated at between about 3 MR and about 5 MR.
Claim 23
Dependent Claim
27 words
A method according to claim 16 wherein said antioxidant is a member selected from the group consisting of 2.6 ditert butyl-4-ethyl phenol (BHEB) and butylated hydroxytoluene (BHT).
Claim 24
Dependent Claim
25 words
A method according to claim 16 wherein said antioxidant in said irradiated inner layer provides BHT Equivalency of between about 500 and about 2000 ppm.
Claim 25
Dependent Claim
24 words
A method according to claim 16 wherein the major constituent of at least one of said inner and outer layers is ethylene vinyl acetate.
Claim 26
Dependent Claim
20 words
A method according to claim 16 wherein the major constituent of said inner and outer layers is ethylene vinyl acetate.
Claim 27
Dependent Claim
30 words
A method according to claim 16 wherein said inner and outer layers are formed of at least one member selected from the group consisting of polyethylene and ethylene vinyl acetate.
Claim 28
Dependent Claim
29 words
A method according to claim 16 wherein said oxygen barrier layer is a member selected from the group consisting of a vinylidene chloride copolymer, ethylene vinyl alcohol and polyamide.
Claim 29
Dependent Claim
147 words
A food storage bag formed of biaxially oriented, differentially cross-linked and heat shrinkable multilayer film irradiated to at least about 2 MR and comprising a thermoplastic inner layer and a thermoplastic outer layer, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.5 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5, with one end of said bag being heat sealed by adhesion between contiguous inner layer surfaces in a direction transverse to the oppositely located side walls of said bag, and with the other mouth end of said bag being impulse heat sealable by fusion bonding between contiguous inner layer surfaces after filling the bag with food.
Claim 30
Dependent Claim
147 words
A food storage bag formed of biaxially oriented, differentially cross-linked and heat shrinkable multilayer film irradiated to at least about 2 MR and comprising a thermoplastic inner layer and a thermoplastic outer layer, the irradiated inner layer containing an antioxidant in sufficient quantity to adjust its melt flow index to at least about 0.5 and the irradiated outer layer having a melt flow index of less than about 0.7, such that the ratio of said melt flow indices of the inner layer to the outer layer is at least about 1.5, with one end of said bag being heat sealed by adhesion between contiguous inner layer surfaces in a direction transverse to the oppositely located side walls of said bag, and with the other mouth end of said bag being impulse heat sealable by fusion bonding between contiguous inner layer surfaces after filling the bag with food.
Claim 31
Dependent Claim
16 words
A bag according to claim 26 wherein said inner and outer irradiated layers are adhered together.
Claim 32
Dependent Claim
27 words
A bag according to claim 26 wherein said inner and outer irradiated layers are separated by an oxygen barrier layer and adhered thereto on opposite sides thereof.
Claim 33
Dependent Claim
27 words
A bag according to claim 26 wherein the ratio of said melt flow indices of the inner layer to the outer layer is at least about 4.
Claim 34
Dependent Claim
20 words
A bag according to claim 26 wherein the melt flow index of said inner irradiated layer is at least 0.7.
Claim 35
Dependent Claim
20 words
A bag according to claim 26 wherein the melt flow index of said inner irradiated layer is at least 1.0.
Claim 36
Dependent Claim
14 words
A bag according to claim 26 wherein the outer layer contains a cross-linking enhancer.
Claim 37
Dependent Claim
20 words
A bag according to claim 28 wherein said film is irradiated at between about 3 MR and about 5 MR.
Claim 38
Dependent Claim
27 words
A bag according to claim 28 wherein said antioxidant is a member selected from the group consisting of 2.6 ditert butyl-4-ethyl phenol (BHEB) and butylated hydroxytoluene (BHT).
Claim 39
Dependent Claim
25 words
A bag according to claim 28 wherein said antioxidant in said irradiated inner layer provides BHT Equivalency of between about 500 and about 2000 ppm.
Claim 40
Dependent Claim
24 words
A bag according to claim 28 wherein said antioxidant in said irradiated inner layer provides BHT Equivalency of between about 800 and 1600 ppm.
Claim 41
Dependent Claim
24 words
A bag according to claim 28 wherein the major constituent of at least one of said inner and outer layers is ethylene vinyl acetate.
Claim 42
Dependent Claim
20 words
A bag according to claim 28 wherein the major constituent of said inner and outer layers is ethylene vinyl acetate.
Claim 43
Dependent Claim
31 words
A bag according to claim 28 wherein said inner and outer irradiated layers are formed of at least one member selected from the group consisting of polyethylene and ethylene vinyl acetate.
Claim 44
Dependent Claim
30 words
A bag according to claim 28 wherein said oxygen barrier layer is a member selected from the group consisting of a vinylidene chloride-vinyl chloride copolymer, ethylene vinyl alcohol and polyamide.
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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) | 1994-10-07 | 1995-04-08 | 1995-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-07 | 1999-04-08 | 1999-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-07 | 2003-04-08 | 2003-10-08 | $7700.00 | Window Closed / Lapsed |