US3883629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Injection molding of laminar articles having a foam core and an integral skin
Assignee: Imperial Chemical Industries Ltd
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Filing: 1972-09-12
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Granted: 1975-05-13
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Expires: 1992-09-12
Abstract
Abstract In a process in which a laminated article is produced by injection moulding by sequentially injecting two charges of thermoplastic material through the same sprue into a mould making the first charge of sufficient size to fill the mould cavity and then enlarging the mould cavity to allow the second charge to be introduced.
Inventors
- 👤 Paul Johnson Garner
- 👤 David Fairclough Oxley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:03
CPC Classifications
B; B32; B32B; B32B21/00; B32B21/04; B32B21/08; B29; B29C; B29C44/00; B29C44/02; B29C44/04; B29C44/0461; B29C44/08; B29C44/083; B29C44/086; B29C45/00; B29C45/16; B29C45/1642; B32B27/00; B32B27/42; C; C08; C08J; C08J9/00; C08J9/34; B29C45/17; B29C45/46; B29C45/56; B29C45/561; B29C2045/563; B29K; B29K2101/00; B29K2101/10; B32B2323/00; B32B2323/04; B32B2323/043; B32B2323/046; B32B2323/10; B32B2331/00; B32B2331/04; B32B2363/00; B32B2367/00; B32B2375/00; Y; Y10; Y10S; Y10S264/00; Y10S264/14; Y10S264/83
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
144 words
IN AN INJECTION MOLDING PROCESS FOR THE PRODUCTION OF LAMINAR ARTICLES HAVING A CORE OF A SYNTHETIC POLYMERIC RESIN COMPOSITION ENCLOSED BY A SKIN OF A DISSIMILAR SYNTHETIC POLYMERIC RESIN COMPOSITION, WHEREIN A MOLTEN CHARGE OF AN INJECTION MOLDABLE SKIN SKIN FORMING SYNTHETIC POLYMERIC RESIN COMPOSITION IS INJECTED INTO A MOLD CAVITY AND, BEFORE THE INTERIOR OF THE SKIN FORMING COMPOSITION HAS SET, A MOLTEN CHARGE OF AN INJECTION MOLDABLE CORE FORMING SYNTHETIC POLYMERIC RESIN COMPOSITION IS INJECTED INTO THE INTERIOR OF THE SKIN FORMING COMPOSITION, AND THE COMPOSITIONS ARE MAINTAINED IN THE MOLD CAVITY UNTIL THEY HAVE SET, THE IMPROVEMENT COMPRISING FILLING THE MOLD CAVITY WITH SAID SKIN FORMING COMPOSITION AND THEN INJECTING THE CORE FORMING COMPOSITION SO THAT THE INJECTION PRESSURE OF THE CORE FORMING COMPOSITION FORCES THE MOLD CAVITY TO ENLARGE TO ACCOMMODATE THE CORE FOORMING COMPOSITION AS IT IS INJECTED.
Claim 2
Dependent Claim
144 words
IN AN INJECTION MOLDING PROCESS FOR THE PRODUCTION OF LAMINAR ARTICLES HAVING A CORE OF A SYNTHETIC POLYMERIC RESIN COMPOSITION ENCLOSED BY A SKIN OF A DISSIMILAR SYNTHETIC POLYMERIC RESIN COMPOSITION, WHEREIN A MOLTEN CHARGE OF AN INJECTION MOLDABLE SKIN SKIN FORMING SYNTHETIC POLYMERIC RESIN COMPOSITION IS INJECTED INTO A MOLD CAVITY AND, BEFORE THE INTERIOR OF THE SKIN FORMING COMPOSITION HAS SET, A MOLTEN CHARGE OF AN INJECTION MOLDABLE CORE FORMING SYNTHETIC POLYMERIC RESIN COMPOSITION IS INJECTED INTO THE INTERIOR OF THE SKIN FORMING COMPOSITION, AND THE COMPOSITIONS ARE MAINTAINED IN THE MOLD CAVITY UNTIL THEY HAVE SET, THE IMPROVEMENT COMPRISING FILLING THE MOLD CAVITY WITH SAID SKIN FORMING COMPOSITION AND THEN INJECTING THE CORE FORMING COMPOSITION SO THAT THE INJECTION PRESSURE OF THE CORE FORMING COMPOSITION FORCES THE MOLD CAVITY TO ENLARGE TO ACCOMMODATE THE CORE FOORMING COMPOSITION AS IT IS INJECTED.
Claim 3
Dependent Claim
22 words
A process according to claim 1 in which the compositions are injected into the mold cavity successively through the same injection orifice.
Claim 4
Dependent Claim
133 words
A process according to claim 1 in which the molD cavity is a vertical flash mold defined by a pair of mold members slidably movable relative to one another to allow the mold cavity to enlarge without permitting loss of the synthetic polymeric resin compositions injected thereinto, said mold members being held in the smaller volume condition by a clamping force, and wherein said clamping force holding said mold members in the smaller volume condition is reduced after filling the mold cavity with the skin forming composition and whereby, on injecting the core forming composition into the mold cavity under pressure, said mold members are forced to slide relative to one another by the injection pressure of the core forming composition against said reduced clamping force so that the mold cavity is enlarged.
Claim 5
Dependent Claim
26 words
A process according to claim 1 wherein, after injecting the core forming composition, a further charge of skin forming composition is injected into the mold cavity.
Claim 6
Dependent Claim
40 words
A process according to claim 1 wherein, the core forming composition contains a blowing agent and is injected into the mold cavity above the foaming temperature thereof and said core forming composition is permitted to foam in the mold cavity.
Claim 7
Dependent Claim
73 words
A process according to claim 5, wherein the core forming composition is injected into the mold cavity and the injection pressure of the core forming composition causes the mold cavity to enlarge to accommodate the core forming composition against a restraining force sufficient to prevent foaming of the core forming composition and, after injection of the core forming composition, the mold cavity is further enlarged to permit the core forming composition to foam.
Claim 8
Dependent Claim
16 words
A process according to claim 1 wherein the skin and core forming compositions are polypropylene compositions.
Claim 9
Dependent Claim
18 words
A process according to claim 1 in which the skin and core forming compositions are polyvinyl chloride compositions.
Claim 10
Dependent Claim
59 words
A process according to claim 1 wherein the volume of the mold cavity is initially larger than the volume of the skin forming composition injected thereinto and, after injection of the skin forming composition, but before injection of the core forming composition, the volume of the mold cavity is reduced whereby the skin forming composition fills the mold cavity.
Claim 11
Dependent Claim
98 words
A process according to claim 1, wherein a material having a melting point at temperatures higher than the temperatures at which the skin and core forming compositions are injected into the mold is placed in the mold cavity as a lining of at least a part thereof before injection of the skin forming composition, whereby said lining becomes bonded to the molded article on the injection of the skin and core forming compositions and allowing the compositions to set, and after said compositions have set, removing the molded article with said lining bonded thereto from the mold cavity.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |