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US4839450A
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US
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Moisture-shrinkable films from starch graft copolymers
Assignee: United States Department of Agriculture
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Filing: 1987-11-17
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Granted: 1989-06-13
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Expires: 2007-11-17
Abstract
Abstract Moisture-shrinkable films can be extrusion blown from modified starch-poly(methyl acrylate) graft compolymers. The films shrink when exposed at room temperature to relative humidities approaching 100%. The films have potential application in shrink-wrapping irregularly shaped articles without application of heat; they are easily removed by water washing.
Inventors
- 👤 George F. Fanta
- 👤 Felix H. Otey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:33
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C61/00; B29C61/003; C08F; C08F251/00; C08L; C08L51/00; C08L51/08; C08J2351/00; C08J2351/08; Y; Y10; Y10S; Y10S260/00; Y10S260/43
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
46 words
A moisture-shrinkable, film-forming composition comprising: (1) a graft copolymer of a hot water-soluble modified starchy material and a synthetic monomer, wherein said monomer is characterized as yielding upon polymerization a polymer having a glass transition temperature of less than about 35° C.; and (2) a plasticizer.
Claim 2
Dependent Claim
46 words
A moisture-shrinkable, film-forming composition comprising: (1) a graft copolymer of a hot water-soluble modified starchy material and a synthetic monomer, wherein said monomer is characterized as yielding upon polymerization a polymer having a glass transition temperature of less than about 35° C.; and (2) a plasticizer.
Claim 3
Dependent Claim
16 words
A composition as described in claim 1 wherein said modified starchy material is a derivatized starch.
Claim 4
Dependent Claim
17 words
A composition as described in claim 1 wherein said modified starchy material is a partially depolymerized starch.
Claim 5
Dependent Claim
30 words
A composition as described in claim 1 wherein the ratio of synthetic monomer to starchy material is in the range of 40:60 to about 70:30 on a dry weight basis.
Claim 6
Dependent Claim
12 words
A composition as described in claim 1 wherein said plasticizer is water.
Claim 7
Dependent Claim
13 words
A composition as described in claim 5 wherein said plasticizer is aqueous urea.
Claim 8
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 1.
Claim 9
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 2.
Claim 10
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 3.
Claim 11
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 4.
Claim 12
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 5.
Claim 13
Dependent Claim
12 words
A dimensionally stable, stretched film produced from the composition of claim 6.
Claim 14
Independent Claim
98 words
A method of preparing a moisture-shrinkable film comprising the steps of: a. blending at a temperature in the range of about 70°-90° C. a composition comprising: (1) a graft copolymer of a hot water-soluble, modified starchy material and a synthetic monomer, wherein said monomer is characterized as yielding upon polymerization a polymer having a glass transition temperature of less than about 35° C.; and (2) a suitable amount of a plasticizer; b. forming said blended composition into a film; c. stretching the film into a stretched state; and d. rendering the film dimensionally stable in the stretched state.
Claim 15
Independent Claim
98 words
A method of preparing a moisture-shrinkable film comprising the steps of: a. blending at a temperature in the range of about 70°-90° C. a composition comprising: (1) a graft copolymer of a hot water-soluble, modified starchy material and a synthetic monomer, wherein said monomer is characterized as yielding upon polymerization a polymer having a glass transition temperature of less than about 35° C.; and (2) a suitable amount of a plasticizer; b. forming said blended composition into a film; c. stretching the film into a stretched state; and d. rendering the film dimensionally stable in the stretched state.
Claim 16
Dependent Claim
12 words
The method as described in claim 13 wherein said plasticizer is water.
Claim 17
Dependent Claim
13 words
The method as described in claim 13 wherein said plasticizer is aqueous urea.
Claim 18
Dependent Claim
18 words
The method as described in claim 15 wherein steps (b), (c) and (d) are accomplished by extrusion blowing.
Claim 19
Dependent Claim
9 words
A film produced by the method of claim 16.
References Cited (Backward Citations)
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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) | 1992-06-12 | 1992-12-12 | 1993-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-12 | 1996-12-12 | 1997-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-12 | 2000-12-12 | 2001-06-13 | $7700.00 | Window Closed / Lapsed |