Patent US4243629A successfully refreshed from Google Patents.
US4243629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for the continuous extrusion and blowing of thin films of plastic material in particular rigid PVC
Assignee: AEP Industries Inc
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Filing: 1979-03-13
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Granted: 1981-01-06
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Expires: 1999-03-13
Abstract
Abstract The heating of the powder of rigid polyvinyl chloride in an extrusion machine of known type presents difficulties and causes burning. According to the invention this is avoided by introducing continuously the raw material in the form of powder after intense mixing with stabilizer and plasticizer in the feed opening of a monoscrew extruder. The said monoscrew extruder has eight different zones: an introduction zone preferably without heating; a slightly heated compression zone; a heated homogenization zone (H); a plasticizing zone; a heated decompression zone (D); a heated degasifying zone (G); a heated compression zone (K 2 ) and a heated expulsion zone. For the plasticizing there is inserted in the extrusion screw before the decompression zone (D) a ring (3) provided with calibrated bores (4 and 5) which obstruct, that is, delay the flow so as to plasticize it without having to increase the temperature.
Inventors
- 👤 Gicancarlo Tramezzani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:50
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/03; B29C48/09; B29C48/10; B29C48/25; B29C48/256; B29C48/2564; B29C48/36; B29C48/395; B29C48/50; B29C48/501
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
96 words
A method for the continuous extrusion and blowing of thin films of plastic material, comprising introducing the raw material into an extruder having a screw, precompressing the material continuously in the cold state in the screw, plasticizing the material by heating, leading the material through a throttling opening along a further portion of the screw, decompressing the material along a subsequent portion of the screw, degassing the material along still another portion of the screw, again increasing the pressure along a still further portion of the screw, and then extruding the material to a thin film.
Claim 2
Independent Claim
96 words
A method for the continuous extrusion and blowing of thin films of plastic material, comprising introducing the raw material into an extruder having a screw, precompressing the material continuously in the cold state in the screw, plasticizing the material by heating, leading the material through a throttling opening along a further portion of the screw, decompressing the material along a subsequent portion of the screw, degassing the material along still another portion of the screw, again increasing the pressure along a still further portion of the screw, and then extruding the material to a thin film.
Claim 3
Dependent Claim
163 words
Apparatus for the continuous extrusion of thin films of plastic material, comprising an extrusion screw, means for feeding the raw material to the extrusion screw, the extrusion screw having, along its length, in the extrusion direction, a compression section in which the screw has a constant outer diameter and an increasing inner diameter and constant pitch, a homogenization zone in which the screw has constant inner and outer diameter and pitch, a plasticization zone in which the material is forced through at least one orifice, a decompression zone in which the screw has constant outer diameter and decreasing inner diameter and constant pitch, a degasification zone in which the screw has constant outer diameter and constant inner diameter and constant pitch with the inner diameter reduced in respect of the preceding diameters, a compression zone in which the screw has constant outer diameter and an increasing inner diameter and a constant pitch, and an expulsion zone from which the extruded material is expelled.
Claim 4
Dependent Claim
163 words
Apparatus for the continuous extrusion of thin films of plastic material, comprising an extrusion screw, means for feeding the raw material to the extrusion screw, the extrusion screw having, along its length, in the extrusion direction, a compression section in which the screw has a constant outer diameter and an increasing inner diameter and constant pitch, a homogenization zone in which the screw has constant inner and outer diameter and pitch, a plasticization zone in which the material is forced through at least one orifice, a decompression zone in which the screw has constant outer diameter and decreasing inner diameter and constant pitch, a degasification zone in which the screw has constant outer diameter and constant inner diameter and constant pitch with the inner diameter reduced in respect of the preceding diameters, a compression zone in which the screw has constant outer diameter and an increasing inner diameter and a constant pitch, and an expulsion zone from which the extruded material is expelled.
Claim 5
Dependent Claim
35 words
Apparatus as claimed in claim 2, and at least one break flow ring surrounding the screw, said at least one orifice extending through the break flow ring in the direction of flow of the material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |