US4244900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the continuous production of a co-extruded heat-shrinkable composite foamed resin sheet
Assignee: Graham Packaging Plastic Products Inc
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Filing: 1979-03-26
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Granted: 1981-01-13
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Expires: 1999-03-26
Abstract
Abstract This invention relates to the treatment of plastic sheet material and especially co-extruded sheet of orientable plastic material which is comprised of film and foam layers which are continuously stretched in a longitudinal direction. The stretching is effected between a pair of rolls which are maintained at different temperatures and rotated at different rates of rotation to effect a cold stretching of the film-foam laminate to improve its shrink capability and lower its shrink temperature upon usage in various packaging applications. A preferred material is polyethylene which is co-extruded into a laminate of film and foam layers and which exhibits improved shrinkage characteristics when employed in the form of tubular sleeves for container labels or bands.
Inventors
- 👤 James E. Heider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:37
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/023; B32; B32B; B32B27/00; B32B27/06; B32B27/065; B29C55/18; B29C61/00; B29C61/06; B29C61/0608; B29C61/0616; B32B27/32; B32B38/00; B32B38/0012; B32B5/00; B32B5/18; B29C48/00; B29C48/001; B29C48/0018; B29C48/03; B29C48/07; B29C48/08; B29C48/16; B29C48/18; B29C48/21; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2105/00; B29K2105/04; B29L; B29L2023/00; B29L2023/001; B32B2038/0028; B32B2266/00; B32B2266/02; B32B2266/0214; B32B2266/025; B32B2305/00; B32B2305/02; B32B2305/022; B32B2307/00; B32B2307/40; B32B2307/406; B32B2307/50; B32B2307/514; B32B2307/70; B32B2307/732; B32B2307/734; B32B2307/736; B32B2309/00; B32B2309/08; B32B2309/10; B32B2309/105; B32B2323/00; B32B2323/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
The method of continuously producing a heat-shrinkable oriented film and foam thermoplastic polyolefin sheet material comprising the steps of co-extruding a layer of film and a layer of foam of said thermoplastic polyolefin material in tubular form, initially stretching the said co-extruded sheet of film and foam thermoplastic material in both longitudinal and transverse directions immediately following its co-extrusion, as a first step; and secondarily stretching the said co-extruded sheet longitudinally by feeding said sheet between the closely spaced peripheral surfaces of a pair of rolls rotating at different peripheral surface speeds, as a subsequent second step; said second step being effected with the temperature of said sheet below the melt point temperature of the polyolefin material, said sheet being lengthened in the range of 50% to 70% of its initially-stretched length by such secondary stretching.
Claim 2
Independent Claim
136 words
The method of continuously producing a heat-shrinkable oriented film and foam thermoplastic polyolefin sheet material comprising the steps of co-extruding a layer of film and a layer of foam of said thermoplastic polyolefin material in tubular form, initially stretching the said co-extruded sheet of film and foam thermoplastic material in both longitudinal and transverse directions immediately following its co-extrusion, as a first step; and secondarily stretching the said co-extruded sheet longitudinally by feeding said sheet between the closely spaced peripheral surfaces of a pair of rolls rotating at different peripheral surface speeds, as a subsequent second step; said second step being effected with the temperature of said sheet below the melt point temperature of the polyolefin material, said sheet being lengthened in the range of 50% to 70% of its initially-stretched length by such secondary stretching.
Claim 3
Dependent Claim
30 words
The method in accordance with claim 1, wherein the adjacent surfaces of said pair of rolls are spaced apart tangentially by a gap ranging from about 15 to 20 mils.
Claim 4
Dependent Claim
34 words
The method in accordance with claim 1, wherein one of said rolls is maintained at a temperature ranging from about 140° F. to 150° F. and the other roll is maintained at ambient temperature.
Claim 5
Dependent Claim
43 words
The method in accordance with claim 1, wherein said co-extruded film and foam sheet is secondarily stretched to reduce its thickness from about 12 mils to about 6 mils to lower the shrink temperature of the material and provide greater total shrink capability.
Claim 6
Dependent Claim
32 words
The method in accordance with claim 1, wherein said pair of rolls have similar cylindrical contours and are operated at different rates of rotation having a ratio of about 2 to 1.
Claim 7
Dependent Claim
36 words
The method in accordance with claim 1, wherein said co-extruded film and foam sheet is mechanically stressed by said secondary stretching operation to provide greater contraction upon heat shrinkage of said sheet around a rigid article.
Claim 8
Dependent Claim
30 words
The method in accordance with claim 1, wherein said co-extruded film and foam sheet is comprised of polyethylene, the film surface having high gloss and smoothness to facilitate its decoration.
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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) | 1984-01-13 | 1984-07-14 | 1985-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-13 | 1988-07-14 | 1989-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-13 | 1992-07-14 | 1993-01-13 | $7700.00 | Window Closed / Lapsed |