US3856442A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dispersion of materials in thermoplastics
Assignee: Imperial Chemical Industries Ltd
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Filing: 1973-09-04
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Granted: 1974-12-24
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Expires: 1993-09-04
Abstract
Abstract Apparatus for producing foamed thermoplastics products comprising a screw extruder provided with a metering pump and associated inlet for injecting controlled amounts of blowing agent into material and provided with a second inlet port connected to a supply of gas at constant pressure for injecting a gaseous blowing agent into the material within the extruder wherein the amount of gas injected is controlled by means of a flow restricting device such as a capillary tube located between the inlet port and the supply of gas.
Inventors
- 👤 B Gallagher
- 👤 A Last
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:15
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/14; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3442; C08J2203/00; C08J2203/14; C08J2300/00; C08J2300/22; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
90 words
Apparatus suitable for the production of extruded foamed synthetic thermoplastic polymeric materials comprising a screw extruder provided with two inlet ports, downstream of the melting zone, through which a liquid and a gaseous blowing agent respectively may be injected, the inlet port for the gaseous blowing agent being connected to a constant pressure supply of gaseous blowing agent via a flow restricting device while the inlet port for the liquid blowing agent is connected to a metering device for delivering a given quantity of liquid blowing agent per unit time.
Claim 2
Dependent Claim
90 words
Apparatus suitable for the production of extruded foamed synthetic thermoplastic polymeric materials comprising a screw extruder provided with two inlet ports, downstream of the melting zone, through which a liquid and a gaseous blowing agent respectively may be injected, the inlet port for the gaseous blowing agent being connected to a constant pressure supply of gaseous blowing agent via a flow restricting device while the inlet port for the liquid blowing agent is connected to a metering device for delivering a given quantity of liquid blowing agent per unit time.
Claim 3
Dependent Claim
17 words
Apparatus as claimed in claim 1 wherein the flow restricting device is a length of capillary tube.
Claim 4
Dependent Claim
26 words
Apparatus as claimed in claim 1 wherein the inlet port for the gaseous blowing agent is donwstream of the inlet port for the liquid blowing agent.
Claim 5
Dependent Claim
40 words
Apparatus as claimed in claim 1 wherein the extruder screw has a section, rotating with the screw and opposite at least the injection port for the liquid blowing agent, wherein the molten thermoplastic is divided into a plurality of streams.
Claim 6
Dependent Claim
35 words
Apparatus as claimed in claim 4 wherein the section of the extruder screw dividing the molten thermoplastic into streams comprises a cylinder rotating with the screw having a plurality of axial channels on its surface.
Claim 7
Dependent Claim
15 words
Apparatus as claimed in claim 5 wherein the cylinder has at least 3 axial channels.
Claim 8
Dependent Claim
23 words
Apparatus as claimed in claim 5 wherein the cylinder has a length at least equal to the internal diameter of the extruder barrel.
Claim 9
Dependent Claim
25 words
Apparatus as claimed in claim 7 wherein the length of the cylinder is from 3 to 6 times the internal diameter of the extruder barrel.
Claim 10
Dependent Claim
31 words
Apparatus as claimed in claim 4 wherein the injection port for the gaseous blowing agent is also located opposite the section of the screw where the thermoplastic is divided into streams.
Claim 11
Dependent Claim
30 words
Apparatus as claimed in claim 4 wherein there is provided a turbine mixing section in the screw after the section wherein the melt is divided into a plurality of streams.
Claim 12
Dependent Claim
31 words
Apparatus as claimed in claim 10 wherein the turbine mixing section comprises a plurality of toothed rotors mounted to rotate with the extruder screw, the teeth of alternate rotors being staggered.
Claim 13
Dependent Claim
53 words
Apparatus as claimed in claim 1 wherein, after the injection ports for the blowing agents, there is provided a section of the screw in the form of a cylinder having a plurality of blind inlet grooves therein communicating with a plurality of outlet grooves via channel sections of lesser depth than said grooves.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |