US3950469A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of a plastic tube to be used as an artificial sausage casing
Assignee: Hoechst AG
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Filing: 1974-05-31
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Granted: 1976-04-13
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Expires: 1994-05-31
Abstract
Abstract This invention relates to a process for the manufacture of a plastic tube suitable for use as a sausage casing, which comprises extruding a crystalline thermoplastic material at a temperature above its crystalline melting point through an annular die of non-uniform cross-section, to produce a tube any cross-section of which varies continuously from a maximum to a minimum, the positions of the minimum and maximum thickness being diametrically opposed, the maximum being 1.3 to 3.0 times as thick as the minimum, cooling the tube to below its crystalline melting point, biaxially orienting the tube, and longitudinally stretching the biaxially oriented tube under conditions such that the temperature of the portion of the tube of maximum thickness is greater than that of the portion of the tube of minimum thickness. The invention also relates to the tube so produced.
Inventors
- 👤 Detlef Gneuss
- 👤 Hans Strutzel
- 👤 Wolfgang Meintzschel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:07
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/28
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
205 words
A process for the manufacture of a plastic tube suitable for use as a sausage casing which comprises extruding polyethylene terephthalate at a temperature above its crystalline melting point through an annular die of non-uniform cross-section to produce a tube having a non-uniform wall thickness around the circumference thereof, said wall thickness varying continuously from a maximum to a minimum, the portion of minimum wall thickness and the portion of maximum wall thickness being diametrically opposed on the circumference of said tube and the maximum being from about 1.3 to 3.0 times as thick as the minimum, cooling the tube below its crystalline melting point, biaxially stretching the tube in the longitudinal direction in the range from about 1 : 3.3 to 1 : 3.8 and in the transverse direction in the range from about 1 : 4 to 1 : 4.6, and thereafter longitudinally stretching the biaxially oriented tube under conditions such that the temperature of the tube portion of maximum wall thickness is in the range from about 120° to 150° C and the temperature of the tube portion of minimum wall thickness is in the range from about 80° to 130° C, while maintaining the thickness profile of the biaxially stretched tube.
Claim 2
Dependent Claim
205 words
A process for the manufacture of a plastic tube suitable for use as a sausage casing which comprises extruding polyethylene terephthalate at a temperature above its crystalline melting point through an annular die of non-uniform cross-section to produce a tube having a non-uniform wall thickness around the circumference thereof, said wall thickness varying continuously from a maximum to a minimum, the portion of minimum wall thickness and the portion of maximum wall thickness being diametrically opposed on the circumference of said tube and the maximum being from about 1.3 to 3.0 times as thick as the minimum, cooling the tube below its crystalline melting point, biaxially stretching the tube in the longitudinal direction in the range from about 1 : 3.3 to 1 : 3.8 and in the transverse direction in the range from about 1 : 4 to 1 : 4.6, and thereafter longitudinally stretching the biaxially oriented tube under conditions such that the temperature of the tube portion of maximum wall thickness is in the range from about 120° to 150° C and the temperature of the tube portion of minimum wall thickness is in the range from about 80° to 130° C, while maintaining the thickness profile of the biaxially stretched tube.
Claim 3
Dependent Claim
25 words
A process as claimed in claim 1 wherein the tube is extruded with a maximum wall thickness 1.3 to 2.3 times the minimum wall thickness.
Claim 4
Dependent Claim
22 words
A process as claimed in claim 1 wherein the post-stretching is carried out at temperatures greater than 80°C but less than 150°C.
Claim 5
Dependent Claim
39 words
A process as claimed in claim 1 wherein the tube, after post-stretching in the range from about 1 : 1.6 to 1 : 2.2, has a diameter about 1.5 to 2.5 times that of the tube as originally extruded.
Claim 6
Dependent Claim
23 words
A process as claimed in claim 1 wherein the tube after post-stretching has a maximum wall thickness 1.7 to 4 times the minimum.
References Cited (Backward Citations)
US1654253A
Cited
US2136566A
Cited
US2925621A
Cited
GB811066A
Cited
GB962435A
Cited
US3229006A
Cited
US3242531A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-13 | 1979-10-13 | 1980-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-13 | 1983-10-13 | 1984-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-13 | 1987-10-13 | 1988-04-13 | $7700.00 | Window Closed / Lapsed |