Patent US4344710A successfully refreshed from Google Patents.
US4344710A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polymer foam extrusion system
Assignee: Pactiv LLC
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Filing: 1980-11-10
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Granted: 1982-08-17
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Expires: 2000-11-10
Abstract
Abstract A continuous foam production system is disclosed wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass. A helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zone to form a foam sheet, tube or other shape. An improved fluid handling system includes storage means for holding at least one of a plurality of disparate volatile liquids under pressure sufficient to maintain a normally gaseous blowing agent in liquified state and cooling means for receiving a pressurized first stream of liquified thermally-gaseous blowing agent and cooling below its autogenous temperature. A pump operatively connected between the cooling means and extruder means increases pressure of the first stream higher than the elevated pressure of the extruder, where it may be combined with a pressurized stream of second liquid blowing agent. Flow control means is provided for injecting a predetermined amount of disparate liquid blowing agents from the first and second streams into the extruder means at elevated pressure to form an extrusion mass.
Inventors
- 👤 D. Emil Johnson
- 👤 Charles M. Krutchen
- 👤 G. Vincent Sharps, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:42
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/127; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3442; B29C44/3446; C08J2203/00; C08J2203/14; C08J2325/00; C08J2325/02; C08J2325/04; C08J2325/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
34 words
A system for producing foamable thermoplastic resin mixture comprising: extruder means for transporting resin under pressure from a feed point to a discharge point through a heating zone, fluid injection zone and mixing zone;
Claim 2
Independent Claim
34 words
A system for producing foamable thermoplastic resin mixture comprising: extruder means for transporting resin under pressure from a feed point to a discharge point through a heating zone, fluid injection zone and mixing zone;
Claim 3
Dependent Claim
112 words
resin supply means for introducing resin to the extruder means at the feed point for melting in the heating zone; storage means for maintaining a plurality of diverse volatile liquids under the autogeneous pressure of the material, at least one of said volatile liquids being normally gaseous; fluid handling means for pressurizing said iquids from said storage means to the fluid injection zone of the extruder means; heat exchange means operatively connected between said storage means and said fluid handling means for cooling the normally-gaseous material to prevent flashing thereof during pumping; and flow metering means operatively connected with the fluid handling means for supplying predetermined amounts of the diverse volatile liquids.
Claim 4
Dependent Claim
112 words
resin supply means for introducing resin to the extruder means at the feed point for melting in the heating zone; storage means for maintaining a plurality of diverse volatile liquids under the autogeneous pressure of the material, at least one of said volatile liquids being normally gaseous; fluid handling means for pressurizing said iquids from said storage means to the fluid injection zone of the extruder means; heat exchange means operatively connected between said storage means and said fluid handling means for cooling the normally-gaseous material to prevent flashing thereof during pumping; and flow metering means operatively connected with the fluid handling means for supplying predetermined amounts of the diverse volatile liquids.
Claim 5
Dependent Claim
37 words
The system of claim 1 wherein the fluid handling means includes conduit means for joining a first normaly gaseous liquid stream and a second normally liquid stream prior to pumping the combined streams into the injection zone.
Claim 6
Dependent Claim
21 words
The system of claim 1 including means for controlling first and second streams of disparate liquid blowing agents in predetermined ratio.
Claim 7
Dependent Claim
33 words
The system of claim 3 wherein said ratio control means comprises means for blending from a single less-volatile blowing agent stream to a fixed ratio with a higher volatility liquid stream during start-up.
Claim 8
Dependent Claim
168 words
In a continuous foam production system wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass and wherein a helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zone; the improvement which comprises: storage means for holding at least one of a plurality of disparate volatile liquids under pressure sufficient to maintain a normally gaseous blowing agent in liquified state; cooling means for receiving a pressurized first stream of liquified thermally-gaseous blowing agent and cooling said first stream below autogenous temperature; pump means operatively connected between the cooling means and extruder means for increasing pressure of the first stream higher than the elevated pressure of the extruder means; a pressurized stream of second liquid blowing agent; and flow control means for injecting a predetermined amount of disparate liquid blowing agents from the first and second streams into the extruder means at elevated pressure to form an extrusion mass.
Claim 9
Dependent Claim
168 words
In a continuous foam production system wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass and wherein a helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zone; the improvement which comprises: storage means for holding at least one of a plurality of disparate volatile liquids under pressure sufficient to maintain a normally gaseous blowing agent in liquified state; cooling means for receiving a pressurized first stream of liquified thermally-gaseous blowing agent and cooling said first stream below autogenous temperature; pump means operatively connected between the cooling means and extruder means for increasing pressure of the first stream higher than the elevated pressure of the extruder means; a pressurized stream of second liquid blowing agent; and flow control means for injecting a predetermined amount of disparate liquid blowing agents from the first and second streams into the extruder means at elevated pressure to form an extrusion mass.
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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) | 1985-08-16 | 1986-02-15 | 1986-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-16 | 1990-02-15 | 1990-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-16 | 1994-02-15 | 1994-08-17 | $7700.00 | Window Closed / Lapsed |