US3950484A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for injection molding a foamed thermoplastic polymer article substantially free from swirl-patterns in its surface
Assignee: Standard Oil Co
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Filing: 1974-08-30
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Granted: 1976-04-13
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Expires: 1994-08-30
Abstract
Abstract A method for producing an improved molded thermoplastic polymeric resinous article comprising: introducing a heat plastified thermoplastic polymeric resinous material into a mold in the presence of a finely divided inorganic material; cooling the heat plastified thermoplastic polymeric resinous material; removing from the mold the cooled mold-shaped thermoplastic polymeric resinous article having finely divided inorganic material incorporated therein.
Inventors
- 👤 Ernst A. Egli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:16
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/38; B29C44/42; B29C44/421; Y; Y10; Y10S; Y10S264/00; Y10S264/05; Y10S264/14; Y10S264/17; Y10S264/83; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249987; Y10T428/249988; Y10T428/249989
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
96 words
A method for producing a foamed thermoplastic polymeric resinous article substantially free from swirl-patterns in its surface comprising: injecting a heat plastified thermoplastic polymeric resinous material into a mold in the presence of a foaming agent and finely divided lithopone particles comprising about 30% zinc sulfide and about 70% barium sulfate and being of a size such that the lithopone particles will pass through a 10 mesh sieve; cooling the heat plastified thermoplastic polymeric resinous material; removing the cooled, foamed, moldshaped, thermoplastic polymeric resinous article having the finely divided lithopone particles incorporated therein from the mold.
Claim 2
Independent Claim
96 words
A method for producing a foamed thermoplastic polymeric resinous article substantially free from swirl-patterns in its surface comprising: injecting a heat plastified thermoplastic polymeric resinous material into a mold in the presence of a foaming agent and finely divided lithopone particles comprising about 30% zinc sulfide and about 70% barium sulfate and being of a size such that the lithopone particles will pass through a 10 mesh sieve; cooling the heat plastified thermoplastic polymeric resinous material; removing the cooled, foamed, moldshaped, thermoplastic polymeric resinous article having the finely divided lithopone particles incorporated therein from the mold.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein the finely divided lithopone particles are combined with the thermoplastic polymeric resinous material before the thermoplastic polymeric resinous material is heat plastified and injected into a mold.
Claim 4
Dependent Claim
14 words
The method of claim 1 wherein the thermoplastic polymeric resinous material is impact polystyrene.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein the thermoplastic polymeric resinous material is high density polyethylene.
Claim 6
Dependent Claim
13 words
The method of claim 1 wherein the thermoplastic polymeric resinous material is polypropylene.
Claim 7
Independent Claim
56 words
A method for injection molding foamed thermoplastic polymeric resinous articles wherein the improvement comprises: admixing into the plastifiable resin finely divided lithopone particles capable of passing through a 10 mesh sieve, the lithopone particles comprising about 30% zinc sulfide and about 70% barium sulfate, to produce articles which are substantially free from swirl-patterns in the surface.
Claim 8
Independent Claim
56 words
A method for injection molding foamed thermoplastic polymeric resinous articles wherein the improvement comprises: admixing into the plastifiable resin finely divided lithopone particles capable of passing through a 10 mesh sieve, the lithopone particles comprising about 30% zinc sulfide and about 70% barium sulfate, to produce articles which are substantially free from swirl-patterns in the surface.
References Cited (Backward Citations)
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US2480821A
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US2512459A
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US2819183A
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US2952041A
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US3437722A
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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) | 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 |