Cellulose acetate and starch based biodegradable injection molded plastics compositions and methods of manufacture
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsJean M. Mayer, Glenn R. Elion
Life of this patent
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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.
Claims19
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.
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.
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.
Dependencies are inferred from the claim text.