PROCESS FOR PRODUCING BIODEGRADABLE THINWALLED STARCH-BASED MOULDINGS

摘要

PCT No. PCT/AT93/00185 Sec. 371 Date May 31, 1995 Sec. 102(e) Date May 31, 1995 PCT Filed Dec. 6, 1993 PCT Pub. No. WO94/13734 PCT Pub. Date Jun. 23, 1994This invention relates to a process applying a water-repellent and/or waterproof coating to at least one side or the inside of shaped elements, which are obtained in that starch-containing compositions are baked between two mould halves or are extruded. That process is characterized in that a lacquer which in addition to one or more low-boiling solvents which are miscible with water and are innocuous from the aspect of human and/or ecotoxicology and one or more rottable film-forming substances and one or more rottable hydrophobic plasticizers is applied and during the application of said lacquer the adsorbed water of hydration is removed from the surface layer of the shaped element which is to be coated, whereafter the solvent mixture is removed which a minimum moisture content from 5% by weight to one at which there is no odour maintained in the substrate. Suitable film-forming substances include alkyl celluloses and non-hydrophobic water-insoluble cellulose esters of the group consisting of cellulose acetate butyrates, cellulose acetate propionates and cellulose acetates. Suitable plasticizers include hydrophobic triglycerides of fatty acids having medium and long chain lengths (chain lengths larger than or equal to C4), triglycerides partly substituted with substituents having shorter chain lengths, and, provided that at least one fatty acid having a chain length larger than or equal to C14 is contained, phthalic acid esters, acylic dicarboxylic acid esters, fully esterified citric acid esters, saccharose acetate isobutyrate and other hydrophobic sugar esters.