US4089818A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reduced aging period for polyethylene foam
Assignee: Leucadia Inc
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Filing: 1976-08-20
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Granted: 1978-05-16
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Expires: 1996-08-20
Abstract
Abstract In accordance with the present invention the aging period for low density polyethylene foam is substantially reduced by forming the foam from at least two different resins having different melt indexes which are blended together.
Inventors
- 👤 Robert C. Slocumb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:08
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/0061; C08J9/04; C08J9/12; C08J9/14; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; C08J2423/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
181 words
In the process of forming polyethylene foam of density no greater than about 10 pounds per cubic foot by extrusion of a thermoplastic melt having a blowing agent incorporated therein and wherein foaming of the thermoplastic melt takes place immediately upon extrusion, the improvement comprising the thermoplastic melt being composed of: (a) at least 25% by weight of a polyethylene resin having a melt index in the range of from about 0.1 to about 1.0; (b) at least 25% by weight of a polyethylene resin having a melt index of from about 1.0 to about 10.0; (c) the melt index of the second said resin being at least about 1.0 greater than the melt index of the first said resin; (d) each said polyethylene resin (a) and (b) having a density of from about 0.910 to about 0.926; (e) at least about 85% by weight of the resin portion of the thermoplastic melt being low density polyethylene resin of density from about 0.910 to about 0.926; (f) the overall melt index of the thermoplastic melt being no greater than about 8.
Claim 2
Dependent Claim
181 words
In the process of forming polyethylene foam of density no greater than about 10 pounds per cubic foot by extrusion of a thermoplastic melt having a blowing agent incorporated therein and wherein foaming of the thermoplastic melt takes place immediately upon extrusion, the improvement comprising the thermoplastic melt being composed of: (a) at least 25% by weight of a polyethylene resin having a melt index in the range of from about 0.1 to about 1.0; (b) at least 25% by weight of a polyethylene resin having a melt index of from about 1.0 to about 10.0; (c) the melt index of the second said resin being at least about 1.0 greater than the melt index of the first said resin; (d) each said polyethylene resin (a) and (b) having a density of from about 0.910 to about 0.926; (e) at least about 85% by weight of the resin portion of the thermoplastic melt being low density polyethylene resin of density from about 0.910 to about 0.926; (f) the overall melt index of the thermoplastic melt being no greater than about 8.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein the thermoplastic melt consists of only the two polyethylene resins (a) and (b).
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein the thermoplastic melt comprises at least three polyethylene resins.
Claim 5
Dependent Claim
29 words
The process of claim 1 wherein the melt index of the second said resin is at least about 2.0 greater than the melt index of the first said resin.
Claim 6
Dependent Claim
29 words
The process of claim 1 wherein the melt index of the second said resin is at least about 2.5 greater than the melt index of the first said resin.
Claim 7
Dependent Claim
17 words
The process of claim 1 wherein the said overall melt index is no greater than about 5.
Claim 8
Dependent Claim
30 words
The process of claim 1 wherein at least about 95% of the resin portion of the thermoplastic melt is low density polyethylene of density from about 0.910 to about 0.926.
Claim 9
Dependent Claim
28 words
The process of claim 1 wherein substantially all of the resin portion of the thermoplastic melt is low density polyethylene of density from about 0.910 to about 0.926.
Claim 10
Dependent Claim
23 words
The process of claim 1 wherein the density of the foam produced is from about 1 to about 6 pounds per cubic foot.
Claim 11
Dependent Claim
175 words
In the process of forming polyethylene foam having a density of from about 2 to about 4 pounds per cubic foot by extrusion of a thermoplastic melt having a blowing agent incorporated therein and wherein foaming of the thermoplastic melt takes place immediately upon extrusion, the improvement comprising the thermoplastic melt being composed of: (a) at least 25% by weight of a polyethylene resin having a melt index in the range of from about 0.1 to about 1.0; (b) at least 25% by weight of a polyethylene resin having a melt index of from about 1.0 to about 10.0; (c) the melt index of the second said resin being at least about 2.0 greater than the melt index of the first said resin; (d) each said polyethylene resin having a density of from about 0.910 to about 0.926; (e) substantially all of the resin in the thermoplastic melt being low density polyethylene of density from about 0.910 to about 0.926; (f) the overall melt index of the thermoplastic melt being no greater than about 5.
Claim 12
Dependent Claim
175 words
In the process of forming polyethylene foam having a density of from about 2 to about 4 pounds per cubic foot by extrusion of a thermoplastic melt having a blowing agent incorporated therein and wherein foaming of the thermoplastic melt takes place immediately upon extrusion, the improvement comprising the thermoplastic melt being composed of: (a) at least 25% by weight of a polyethylene resin having a melt index in the range of from about 0.1 to about 1.0; (b) at least 25% by weight of a polyethylene resin having a melt index of from about 1.0 to about 10.0; (c) the melt index of the second said resin being at least about 2.0 greater than the melt index of the first said resin; (d) each said polyethylene resin having a density of from about 0.910 to about 0.926; (e) substantially all of the resin in the thermoplastic melt being low density polyethylene of density from about 0.910 to about 0.926; (f) the overall melt index of the thermoplastic melt being no greater than about 5.
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) | 1981-05-15 | 1981-11-14 | 1982-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-15 | 1985-11-14 | 1986-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-15 | 1989-11-14 | 1990-05-16 | $7700.00 | Window Closed / Lapsed |