US4390581A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Moulding
Assignee: Imperial Chemical Industries Ltd
•
Filing: 1981-02-26
•
Granted: 1983-06-28
•
Expires: 2001-02-26
Abstract
Abstract Articles are blow moulded from thermoplastic polymeric materials containing high proportions of fillers such as glass fibres. The method comprises extruding the filled polymeric material through a die having a mandrel for constraining the material into a tubular shape; coextruding between the die and the outer surface of the material, a liquid having a freezing temperature lower than that of the material; cooling the liquid and the outer surface of the material during their passage through the die to a temperature below the freezing temperature of the material but above the freezing temperature of the liquid while maintaining the inner surface of the material molten; squeezing the extrudate at suitable intervals to fuse the molten inner surface together and thereby seal discrete lengths; and inflating the sealed lengths to conform to a surrounding mould to produce laminar shapes which are then foamed-filled to give stiff panels.
Inventors
- 👤 Frederic N. Cogswell
- 👤 David T. Mitchell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:00
CPC Classifications
B; B29; B29C; B29C49/00; B29C49/22; B29C48/00; B29C48/25; B29C48/78; B29C48/86; B29C48/865; B29C48/87; B29C48/872; B29C49/02; B29C49/04; B29C49/42; B29C49/64; B29C49/6409; B29C49/6436; B29C49/6454; B29C35/00; B29C35/16; B29C48/03; B29C48/09; B29C48/94; Y; Y10; Y10T; Y10T428/00; Y10T428/23; Y10T428/233
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
244 words
A method for producing a shaped article which comprises extruding a thermoplastic polymeric material, initially in a molten state, through a die having a mandrel for constraining the material into a tubular shape and producing thereby a tubular extrudate having an outer surface and an inner surface; coextruding between the die and the outer surface of the polymeric material, a liquid having a freezing temperature lower than that of the polymeric material; cooling the liquid and the outer surface of the polymeric material during their passage through the die, to a temperature below the freezing temperature of the polymeric material but above the freezing temperature of the liquid, while maintaining the inner surface of the polymeric material molten; squeezing the extrudate at suitable intervals to fuse the molten inner surface together and thereby seal discrete lengths; and inflating a sealed length to conform to a surrounding mould, thereby to produce the shaped article, characterised in that the method is applied to a thermoplastic material containing a filler, the ratio of filler to thermoplastic material being at least 15:85 by weight, and that the sealed length of extrudate is moulded into an article with two closely-spaced substantially parallel walls enclosing a volume therebetween, a foamable composition is injected into the enclosed volume and the composition is allowed or caused to foam while the article is held within a constraining means constructed to prevent outward displacement of the spaced-apart walls by pressure from the foaming composition.
Claim 2
Independent Claim
244 words
A method for producing a shaped article which comprises extruding a thermoplastic polymeric material, initially in a molten state, through a die having a mandrel for constraining the material into a tubular shape and producing thereby a tubular extrudate having an outer surface and an inner surface; coextruding between the die and the outer surface of the polymeric material, a liquid having a freezing temperature lower than that of the polymeric material; cooling the liquid and the outer surface of the polymeric material during their passage through the die, to a temperature below the freezing temperature of the polymeric material but above the freezing temperature of the liquid, while maintaining the inner surface of the polymeric material molten; squeezing the extrudate at suitable intervals to fuse the molten inner surface together and thereby seal discrete lengths; and inflating a sealed length to conform to a surrounding mould, thereby to produce the shaped article, characterised in that the method is applied to a thermoplastic material containing a filler, the ratio of filler to thermoplastic material being at least 15:85 by weight, and that the sealed length of extrudate is moulded into an article with two closely-spaced substantially parallel walls enclosing a volume therebetween, a foamable composition is injected into the enclosed volume and the composition is allowed or caused to foam while the article is held within a constraining means constructed to prevent outward displacement of the spaced-apart walls by pressure from the foaming composition.
Claim 3
Dependent Claim
29 words
A method according to claim 1 in which the filler is anisotropic and the ratio of filler to polymeric material is equal to or less than 4:6 by weight.
Claim 4
Dependent Claim
15 words
A method according to claim 2 in which the filler consists essentially of glass fibres.
Claim 5
Dependent Claim
29 words
A method according to claim 1 in which the filler is substantially isotropic, and in which the ratio of filler to polymeric material is less than 6:4 by weight.
Claim 6
Dependent Claim
19 words
A method according to claim 1 in which the constraining means is the mould used to shape the articles.
Claim 7
Dependent Claim
48 words
A method according to claim 1 which comprises inflating a length of polymeric material to conform to the shape of the mould, cooling the mould to harden the extrudate sufficiently to retain its moulded shape and thereafter venting the double-walled article thus formed before injecting the foamable material.
Claim 8
Dependent Claim
26 words
A method according to claim 1 characterised in that the foamable composition comprises a diisocyanate and a diol which react together to give a polyurethane foam.
Claim 9
Dependent Claim
67 words
A car body panel comprising two closely-spaced substantially parallel walls enclosing a volume therebetween which is filled with foam, made by a method according to claim 1, in which each wall comprises a layer of thermoplastic material containing filler surrounded by a layer of a different thermoplastic material of which the freezing temperature of the outer thermoplastic material is lower than that of the filled thermoplastic material.
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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) | 1986-06-27 | 1986-12-27 | 1987-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-27 | 1990-12-27 | 1991-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-27 | 1994-12-27 | 1995-06-28 | $7700.00 | Window Closed / Lapsed |