US5288318A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cellulose acetate and starch based biodegradable injection molded plastics compositions and methods of manufacture
Assignee: United States Department of the Army
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Filing: 1993-07-01
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Granted: 1994-02-22
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Expires: 2013-07-01
Abstract
Abstract A method and composition are provided for making biodegradable injection ded parts from 30% to 70% cellulose acetate, 10% to 60% unmodified raw (whole) starch and 5% to 35% plasticizer including glycerols and glycerol acetates. Other ingredients that can be used include: starch, flour and paper acetates; gelatin; boric acid; and agricultural fillers. The solid ingredients are combined and fed to an extruder used to make pellets or to feed injection molding equipment. The resulting parts are clear to white or colorful depending upon the added filler materials. The plastics formed are water resistant, high strength and biodegradable.
Inventors
- 👤 Jean M. Mayer
- 👤 Glenn R. Elion
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:52
CPC Classifications
C; C08; C08L; C08L1/00; C08L1/08; C08L1/10; C08L1/12; C08L3/00; C08L3/02; C08L2201/00; C08L2201/06
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
68 words
A biodegradable plastic comprising: between about 10% to 60% by weight starch which contains more than 3% intact starch granules; between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 Daltons and a viscosity of 3 to 44 seconds; and between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, ethylene glycol, propylene glycol and glycerol.
Claim 2
Dependent Claim
68 words
A biodegradable plastic comprising: between about 10% to 60% by weight starch which contains more than 3% intact starch granules; between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 Daltons and a viscosity of 3 to 44 seconds; and between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, ethylene glycol, propylene glycol and glycerol.
Claim 3
Dependent Claim
34 words
The biodegradable plastic of claim 1 wherein the said plasticizer is a blend of two or more of those listed in the group consisting of triacetin, diacetin, monoacetin, ethylene glycol, propylene glycol and glycerol.
Claim 4
Dependent Claim
17 words
The biodegradable plastic of claim 1 further comprising between about 0.1% to 3% by weight boric acid.
Claim 5
Dependent Claim
31 words
The biodegradable plastic of claim 1 further comprising between about 0.5% and 8% by weight gelling agent selected from the group consisting of gellan gum, xanthum gum, alkali alginates and Carrageenan.
Claim 6
Dependent Claim
16 words
The biodegradable plastic of claim 1 further comprising between about 0.5% and 8% by weight shellac.
Claim 7
Dependent Claim
32 words
The biodegradable plastic of claim 1 further comprising between about 0.5% and 10% by weight of an agricultural filler selected from the group consisting of milled crustacean shell and nut shell powders.
Claim 8
Dependent Claim
29 words
The biodegradable plastic of claim 1 wherein the said starch is selected from the group consisting of corn, tapioca, potato, sago, wheat, rye, pea, sorghum, rice and arrowroot starch.
Claim 9
Dependent Claim
12 words
The biodegradable plastic of claim 1 wherein the said starch is cornstarch.
Claim 10
Dependent Claim
17 words
The biodegradable plastic of claim 8 wherein the said cornstarch contains between about 30% and 75% amylose.
Claim 11
Dependent Claim
27 words
The biodegradable plastic of claim 1 wherein the said cellulose acetate is partially substituted with paper acetate in the weight range of 1% to 40% by weight.
Claim 12
Dependent Claim
28 words
The biodegradable plastic of claim 1 wherein the said cellulose acetate is partially substituted with natural fiber acetate in the weight range of 1% to 8% by weight.
Claim 13
Dependent Claim
27 words
The biodegradable plastic of claim 1 wherein the said cellulose acetate is partially substituted with starch acetate in the weight range of 1% to 40% by weight.
Claim 14
Dependent Claim
27 words
The biodegradable plastic of claim 1 wherein the said cellulose acetate is partially substituted with flour acetate in the weight range of 1% to 40% by weight.
Claim 15
Dependent Claim
36 words
The biodegradable plastic of claim 1 wherein the said cellulose acetate is partially substituted with a blend of acetate materials and wherein the total acetate substitution blend is in the weight range of 1% to 40%.
Claim 16
Dependent Claim
30 words
An extruded or molded product formed from the biodegradable plastic of claim 1 wherein the said extruded or molded product has a tensile strength of at least about 2,400 psi.
Claim 17
Independent Claim
130 words
A method of forming a biodegradable plastic, the method comprising the following steps: combining on a per weight basis between about 10% to 60% by weight whole starch granules, and between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 and a viscosity of 3 to 44 seconds to form a first mixture of dry ingredients; combining between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, ethylene glycol, propylene glycol and glycerol, with said first mixture of dry ingredients to form a free flowing second mixture; extruding said second mixture through a die to form pellets of plastic having at least 3% intact starch granules; and processing the pellets through an injection molder to produce molded items.
Claim 18
Independent Claim
130 words
A method of forming a biodegradable plastic, the method comprising the following steps: combining on a per weight basis between about 10% to 60% by weight whole starch granules, and between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 and a viscosity of 3 to 44 seconds to form a first mixture of dry ingredients; combining between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, ethylene glycol, propylene glycol and glycerol, with said first mixture of dry ingredients to form a free flowing second mixture; extruding said second mixture through a die to form pellets of plastic having at least 3% intact starch granules; and processing the pellets through an injection molder to produce molded items.
Claim 19
Dependent Claim
23 words
The method of claim 16 wherein a temperature between 100° C. and 170° C. is maintained for all heated zones including the die.
Claim 20
Independent Claim
127 words
A method of forming a biodegradable plastic, the method comprising the following steps: combining on a per weight basis between about 10% to 60% by weight whole starch granules, and between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 and a viscosity of 3 to 44seconds to form a first mixture of dry ingredients; combining between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, propylene glycol, glycerol and ethylene glycol, to said first mixture of dry ingredients to form a second mixture which is a free flowing uniform powder; and extruding said second mixture through a heated barrel directly into injection molds to form a plastic having at least 3% intact starch granules.
Claim 21
Independent Claim
127 words
A method of forming a biodegradable plastic, the method comprising the following steps: combining on a per weight basis between about 10% to 60% by weight whole starch granules, and between 30% to 70% cellulose acetate which has a molecular weight ranging from 28,000 to 62,000 and a viscosity of 3 to 44seconds to form a first mixture of dry ingredients; combining between 5% and 35% of a plasticizer selected from the group consisting of triacetin, diacetin, monoacetin, propylene glycol, glycerol and ethylene glycol, to said first mixture of dry ingredients to form a second mixture which is a free flowing uniform powder; and extruding said second mixture through a heated barrel directly into injection molds to form a plastic having at least 3% intact starch granules.
Claim 22
Dependent Claim
24 words
The method of claim 18 wherein a temperature between 100° C. and 170° C. is maintained for all heated zones including the heated barrel.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-02-21 | 1997-08-23 | 1998-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-21 | 2001-08-23 | 2002-02-22 | $3760.00 | Window Closed / Lapsed |
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