US4226946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyethylene blend foams having improved compressive strength
Assignee: Dow Chemical Co
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Filing: 1979-02-22
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Granted: 1980-10-07
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Expires: 1999-02-22
Abstract
Abstract Low density foams from polyethylene blends having substantially closed cell structure and improved compressive strength are prepared using gel-forming extrusion technology. The polyethylene blend comprises from about 35 to about 60 weight percent of low density branched polyethylene in admixture with from about 40 to about 65 weight percent of intermediate density linear polyethylene. An exemplary blowing agent is 1,2-dichlorotetrafluoroethane, there being up to about 0.12 gram-mole of such blowing agent per 100 grams of resin blend in the flowable gel.
Inventors
- 👤 Chung P. Park
- 👤 Richard A. Bouton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:05
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/0061; C08J9/04; C08J9/12; C08J9/14; C08J9/143; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; C08J2423/00
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
157 words
In a method of making polymer resin foams by the process of extrusion foaming wherein a normally solid thermoplastic resin is heat-plastified and mixed with at least one blowing agent to form a flowable gel which is then passed through a die opening into a zone of lower pressure to cause expansion of the extruded material which is then cooled to form a cellular resinous body, the improvement wherein the thermoplastic resin comprises a polyethylene blend comprising about 35 to about 60 weight percent of low density branched polyethylene having a density from about 0.910 to about 0.930 in admixture with from about 40 to about 65 weight percent of intermediate density linear polyethylene having a density from about 0.931 to 0.940 thereby producing polyethylene blend foams having density of from about 3.0 to about 15.0 pounds per cubic foot, substantially closed-cell structure and compressive strength at 10% deformation of from about 7 to about 170 psi.
Claim 2
Dependent Claim
157 words
In a method of making polymer resin foams by the process of extrusion foaming wherein a normally solid thermoplastic resin is heat-plastified and mixed with at least one blowing agent to form a flowable gel which is then passed through a die opening into a zone of lower pressure to cause expansion of the extruded material which is then cooled to form a cellular resinous body, the improvement wherein the thermoplastic resin comprises a polyethylene blend comprising about 35 to about 60 weight percent of low density branched polyethylene having a density from about 0.910 to about 0.930 in admixture with from about 40 to about 65 weight percent of intermediate density linear polyethylene having a density from about 0.931 to 0.940 thereby producing polyethylene blend foams having density of from about 3.0 to about 15.0 pounds per cubic foot, substantially closed-cell structure and compressive strength at 10% deformation of from about 7 to about 170 psi.
Claim 3
Dependent Claim
23 words
The method according to claim 1 wherein the blend foams have density of from about 3.0 to about 7.0 pounds per cubic foot.
Claim 4
Dependent Claim
24 words
The method according to claim 2 wherein the blend foams have compressive strength at 10% deformation of from about 7 to about 60 psi.
Claim 5
Dependent Claim
24 words
The method according to claim 1 wherein the polyethylenes in the blend have a difference in melt index values of less than 3.0 therebetween.
Claim 6
Dependent Claim
14 words
A method according to claim 1 wherein the blowing agent is 1,2-dichlorotetrafluoroethane or 1-chloro-1,1-difluoroethane.
Claim 7
Dependent Claim
14 words
A method according to claim 1 wherein the blowing agent is 1-chloro-1,2,2,2-tetrafluoroethane or 1-chloro-1,1,2,2-tetrafluoroethane.
Claim 8
Dependent Claim
121 words
As an article of manufacture, a polyethylene blend foam having substantially closed-cell structure, dimensional stability, and compressive strength at 10% deformation of from about 7 to about 170 psi, wherein said blend comprises from about 35 to about 60 weight percent of low density branched polyethylene having a density from about 0.910 to about 0.930 in admixture with from about 40 to about 65 weight percent of intermediate density linear polyethylene, having a density from about 0.931 to about 0.940 said foam having density from about 3.0 to about 15.0 pounds per cubic foot and further characterized in that the gas space of said foam cells originally comprises as an essential constituent at least one volatile material used as blowing agent.
Claim 9
Dependent Claim
121 words
As an article of manufacture, a polyethylene blend foam having substantially closed-cell structure, dimensional stability, and compressive strength at 10% deformation of from about 7 to about 170 psi, wherein said blend comprises from about 35 to about 60 weight percent of low density branched polyethylene having a density from about 0.910 to about 0.930 in admixture with from about 40 to about 65 weight percent of intermediate density linear polyethylene, having a density from about 0.931 to about 0.940 said foam having density from about 3.0 to about 15.0 pounds per cubic foot and further characterized in that the gas space of said foam cells originally comprises as an essential constituent at least one volatile material used as blowing agent.
Claim 10
Dependent Claim
23 words
An article of manufacture according to claim 7 wherein said blend foam has density from about 3.0 to 7.0 pounds per cubic foot.
Claim 11
Dependent Claim
26 words
An article of manufacture according to claim 7 wherein the polyethylenes in the blend have a difference in melt index values of less than 3.0 therebetween.
Claim 12
Dependent Claim
14 words
An article of manufacture according to claim 7 wherein the volatile material is 1,2-dichlorotetrafluoroethane.
Claim 13
Dependent Claim
16 words
An article of manufacture according to claim 6 wherein the volatile material is 1-chloro-1,2,2,2-tertafluoroethane or 1-chloro-1,1,2,2-tetrafluoroethane.
Claim 14
Dependent Claim
14 words
An article of manufacture according to claim 7 wherein the volatile material is 1-chloro-1,1-difluoroethane.
Claim 15
Dependent Claim
14 words
An article of manufacture according to claim 7 wherein the volatile material is 1,1,1-trifluoropropane.
Claim 16
Dependent Claim
23 words
An article of manufacture according to claim 7 wherein the gas space of said foam cells ultimately comprises as an essential constituent air.
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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) | 1983-10-07 | 1984-04-07 | 1984-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-07 | 1988-04-07 | 1988-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-07 | 1992-04-07 | 1992-10-07 | $7700.00 | Window Closed / Lapsed |