US3879507A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing a foam-form flat film or sheet having a more balanced machine and traverse direction strength
Assignee: Mobil Oil AS
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Filing: 1973-02-26
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Granted: 1975-04-22
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Expires: 1993-02-26
Abstract
Abstract Improvements in the extrusion production of foam-form film or sheeting plastic products in order to balance the strength characteristics thereof without significantly varying other overall product characteristics, such as size, production rate and bulk density. These improvements are obtained by varying the configuration of the extrusion die so as to decrease the die gap, increasing the die land length and increasing the exit angle of the die with respect to the axis of the foam-form film or sheeting produced thereby.
Inventors
- 👤 Anthony John Cavanna
- 👤 Edward Armando Colombo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:50
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/50; B29C44/507; B29L; B29L2023/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
217 words
In the process of producing foam-form thermoplastic film or sheeting by extruding a foamable composition comprising a thermoplastic resin and a foaming agent through an annular die of given diameter, gap thickness and die gap angle of divergence from its axis to form a tubular, foam form thermoplastic extrudate of given diameter; drawing said tubular extrudate over a forming mandrel of given diameter larger than the diameter of said die and said extrudate tube; slitting said tubular extrudate, after drawing such over said forming mandrel, to produce a flat film or sheet of said foam extrudate of given width; and taking up said flat extrudate at a given linear speed so as to produce as a product, a flat, biaxially oriented foamform film or sheet of said given width, a given bulk density, and given machine and transverse direction strengths; the improvement, whereby a foam-form flat film or sheet of said given width and bulk density is producecd with more balanced machine and transverse direction strength, which comprises reducing said die gap thickness, increasing said die gap angle of divergence and extruding said composition through said annular die having said smaller die gap thickness than said given die gap thickness and having a larger die gap angle of divergence than said given die gap angle of divergence.
Claim 2
Dependent Claim
217 words
In the process of producing foam-form thermoplastic film or sheeting by extruding a foamable composition comprising a thermoplastic resin and a foaming agent through an annular die of given diameter, gap thickness and die gap angle of divergence from its axis to form a tubular, foam form thermoplastic extrudate of given diameter; drawing said tubular extrudate over a forming mandrel of given diameter larger than the diameter of said die and said extrudate tube; slitting said tubular extrudate, after drawing such over said forming mandrel, to produce a flat film or sheet of said foam extrudate of given width; and taking up said flat extrudate at a given linear speed so as to produce as a product, a flat, biaxially oriented foamform film or sheet of said given width, a given bulk density, and given machine and transverse direction strengths; the improvement, whereby a foam-form flat film or sheet of said given width and bulk density is producecd with more balanced machine and transverse direction strength, which comprises reducing said die gap thickness, increasing said die gap angle of divergence and extruding said composition through said annular die having said smaller die gap thickness than said given die gap thickness and having a larger die gap angle of divergence than said given die gap angle of divergence.
Claim 3
Dependent Claim
217 words
In the process of producing foam-form thermoplastic film or sheeting by extruding a foamable composition comprising a thermoplastic resin and a foaming agent through an annular die of given diameter, gap thickness and die gap angle of divergence from its axis to form a tubular, foam form thermoplastic extrudate of given diameter; drawing said tubular extrudate over a forming mandrel of given diameter larger than the diameter of said die and said extrudate tube; slitting said tubular extrudate, after drawing such over said forming mandrel, to produce a flat film or sheet of said foam extrudate of given width; and taking up said flat extrudate at a given linear speed so as to produce as a product, a flat, biaxially oriented foam-form film or sheet of said given width, a given bulk density, and given machine and transverse direction strengths; the improvement, whereby a foam-form flat film or sheet of said given width and bulk density is producecd with more balanced machine and transverse direction strength, which comprises reducing said die gap thickness, increasing said die gap angle of divergence and extruding said composition through said annular die having said smaller die gap thickness than said given die gap thickness and having a larger die gap angle of divergence than said given die gap angle of divergence.
Claim 4
Dependent Claim
217 words
In the process of producing foam-form thermoplastic film or sheeting by extruding a foamable composition comprising a thermoplastic resin and a foaming agent through an annular die of given diameter, gap thickness and die gap angle of divergence from its axis to form a tubular, foam form thermoplastic extrudate of given diameter; drawing said tubular extrudate over a forming mandrel of given diameter larger than the diameter of said die and said extrudate tube; slitting said tubular extrudate, after drawing such over said forming mandrel, to produce a flat film or sheet of said foam extrudate of given width; and taking up said flat extrudate at a given linear speed so as to produce as a product, a flat, biaxially oriented foam-form film or sheet of said given width, a given bulk density, and given machine and transverse direction strengths; the improvement, whereby a foam-form flat film or sheet of said given width and bulk density is producecd with more balanced machine and transverse direction strength, which comprises reducing said die gap thickness, increasing said die gap angle of divergence and extruding said composition through said annular die having said smaller die gap thickness than said given die gap thickness and having a larger die gap angle of divergence than said given die gap angle of divergence.
Claim 5
Dependent Claim
21 words
The improved process claimed in claim 1 wherein said die gap angle of emergence is about 20* to 45 * degrees.
Claim 6
Dependent Claim
23 words
The improved process claimed in claim 1 wherien the ratio of final foam thickness to die gap thickness is about 4 to 7.
Claim 7
Dependent Claim
43 words
The improved process claimed in claim 1 wherein said thermoplastic is polystyrene, said foaming agent is pentane and the ratio of the diameter of the drawn foam form tubular film to the nominal diameter of the extrusion die is about 4.5 to 6.
Claim 8
Dependent Claim
21 words
The improved process claimed in claim 1 including tapering the die gap about 1* to 5* in the direction of extrusion.
Claim 9
Dependent Claim
18 words
The improved process claimed in claim 5 including increasing the length of the land of the extrusion die.
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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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |