US3624192A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of foamed resins
Assignee: MENSANTO CHEMICALS Ltd
•
Filing: 1968-05-06
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Granted: 1971-11-30
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Expires: 1988-05-06
Abstract
Abstract Die assemblies and processes for extruding a foamable thermoplastic polyvinylaromatic resin through a rectangular die orifice into a zone of lower pressure such that foaming of the resin occurs as it moves through the zone, said zone being defined by a pair of opposing concave surfaces maintained at a temperature lower than the extrusion temperature and curved so that they substantially conform to the corresponding surfaces of the freely expanding resin without exerting a substantial compressive force thereon. The die assemblies and processes are particularly useful for the production of low-density foamed boards having smooth surfaces.
Inventors
- 👤 John Gerald Mccoy
- 👤 William Rees Foster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:25
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/468; B29C44/50; B29C44/505; B29L; B29L2007/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
100 words
A process for the production of foamed thermoplastic polyvinylaromatic resins having an improved surface finish which comprises extruding a foamable thermoplastic polyvinylaromatic resin through a rectangular die orifice into a zone of lower pressure such that foaming of the resin occurs as it moves through the zone, said zone being defined by a pair of opposing concave surfaces maintained at a temperature lower than the extrusion temperature and curved so that they substantially conform to the corresponding surfaces of the freely expanding resin whereby substantially no compressive force is exerted by said opposing concave surfaces upon said freely expanding resin.
Claim 2
Dependent Claim
100 words
A process for the production of foamed thermoplastic polyvinylaromatic resins having an improved surface finish which comprises extruding a foamable thermoplastic polyvinylaromatic resin through a rectangular die orifice into a zone of lower pressure such that foaming of the resin occurs as it moves through the zone, said zone being defined by a pair of opposing concave surfaces maintained at a temperature lower than the extrusion temperature and curved so that they substantially conform to the corresponding surfaces of the freely expanding resin whereby substantially no compressive force is exerted by said opposing concave surfaces upon said freely expanding resin.
Claim 3
Dependent Claim
10 words
The process of claim 1 wherein the resin is polystyrene.
Claim 4
Dependent Claim
36 words
The process of claim 1 wherein the die has a plurality of obstructions transversely distributed therein whereby substantial resistance to the flow of the foamable resin is provided and back pressure within the die is increased.
Claim 5
Dependent Claim
51 words
The process of claim 3 wherein the die has extending into it at its inlet end a plurality of separate channels communicating with a number of slits arranged in the form of a network at the outlet end of the die, each slit having a row of channels associated with it.
Claim 6
Dependent Claim
47 words
The process of claim 4 wherein each of at least the majority of the meshes of the slit network has a substantially central passage leading back from the front face of the die to the inlet end of the die and not communicating directly with the slits.
Claim 7
Dependent Claim
71 words
The process of claim 5 wherein grooves extending from the outlet end of each of at least the majority of the passages toward the outlet of its surrounding mesh of slits are provided in the front face of the die to assist in ensuring that a strand of foamed resin extruded from each passage substantially fills the space formed by the enveloping foamed resin issuing from the surrounding mesh of slits.
Claim 8
Dependent Claim
27 words
The process of claim 1 wherein the zone-defining surfaces have a concave curved cross section that conforms exactly to the corresponding surfaces of the freely expanding resin.
Claim 9
Dependent Claim
21 words
The process of claim 1 wherein the zone-defining surfaces have a concave cross section corresponding to an arc of a circle.
Claim 10
Dependent Claim
28 words
The process of claim 1 wherein the zone-defining surfaces reach their greatest distance apart where the foamed resin is completely expanded and thereafter extend parallel to each other.
References Cited (Backward Citations)
CA451864A
Cited
US2537977A
Cited
US2687997A
Cited
US2644983A
Cited
US2893877A
Cited
US3406230A
Cited
US3431164A
Cited
US3431163A
Cited
US3427371A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-29 | 1975-05-31 | 1975-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-29 | 1979-05-31 | 1979-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-29 | 1983-05-31 | 1983-11-30 | $7700.00 | Window Closed / Lapsed |