US4430288A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Making coextruded sheets and containers
Assignee: Nouryon Surface Chemistry AB
•
Filing: 1981-12-18
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Granted: 1984-02-07
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Expires: 2001-12-18
Abstract
Abstract A multilayered thermoplastic sheet suitable for thermoforming into containers, the sheet being simply and expeditiously prepared and provided with consistent and reliable bonds between layers in a single process step by coextruding a layer of a polyolefin having moisture barrier properties and a specific gravity greater than 0.9 with a polyester layer, to provide chemical resistance, microwave heatability, and quick and inexpensive thermoforming for the multilayered sheet.
Inventors
- 👤 Laszlo J. Bonis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:27
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/14; B29C48/00; B29C48/03; B29C48/07; B29C48/08; B29C48/16; B29C48/18; B29C48/21; B29C48/25; B29C48/30; B29C48/305; B29C48/307; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/1352
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
136 words
A method of making a multilayered structure, said method comprising coextruding by separately heating a polyolefin having moisture barrier properties and a specific gravity greater than 0.9 and polyester, supplying said heated polyolefin and polyester to a coextrusion block to form a multilayer stream with a layer of said polyolefin having moisture barrier properties and a specific gravity greater than 0.9, and a layer of said polyester, and flattening said multilayer stream in a coextrusion die to produce a multilayer sheet having a width greater than the width of said multilayer stream, a thickness less than the height of said multilayer stream, a polyester layer and a polyolefin layer, said polyester layer providing chemical resistance, mircowave heatability and thermoformability during manufacture, said sheet having consistent and reliable bonds between layers owing to its having been coextruded.
Claim 2
Independent Claim
136 words
A method of making a multilayered structure, said method comprising coextruding by separately heating a polyolefin having moisture barrier properties and a specific gravity greater than 0.9 and polyester, supplying said heated polyolefin and polyester to a coextrusion block to form a multilayer stream with a layer of said polyolefin having moisture barrier properties and a specific gravity greater than 0.9, and a layer of said polyester, and flattening said multilayer stream in a coextrusion die to produce a multilayer sheet having a width greater than the width of said multilayer stream, a thickness less than the height of said multilayer stream, a polyester layer and a polyolefin layer, said polyester layer providing chemical resistance, mircowave heatability and thermoformability during manufacture, said sheet having consistent and reliable bonds between layers owing to its having been coextruded.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein said coextruding includes coextruding an adhesive tie layer between said polyester and polyolefin layers.
Claim 4
Dependent Claim
12 words
The method of claim 1 or 2 wherein said polyolefin is polypropylene.
Claim 5
Dependent Claim
42 words
The method of claim 2 wherein said coextruding includes coextruding an adhesive tie layer and a polyester layer on the other side of said polyolefin layer to result in a five-layer structure that has resistance to curling owing to the symmetrical structure.
Claim 6
Independent Claim
20 words
The method of claims 1, 2 or 4 further comprising thermoforming said sheet into the desired shape of a container.
Claim 7
Dependent Claim
15 words
The method of claim 1 wherein said multilayer stream has a generally circular cross section.
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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) | 1987-02-06 | 1987-08-08 | 1988-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-06 | 1991-08-08 | 1992-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-06 | 1995-08-08 | 1996-02-07 | $7700.00 | Window Closed / Lapsed |