Abstract: A preparation process of a degradable copolymer comprising carrying out dehydration polycondensation of polysaccharide (A) with one or more compounds (B) selected from the group consisting of:(b1) hydroxycarboxylic acid,(b2) polyhydroxycarboxylic acid,(b3) aliphatic polyhydric alcohol and aliphatic polybasic acid, and(b4) aliphatic polyester derived from aliphatic polyhydric alcohol and aliphatic polybasic acid.A copolymer having a high molecular weight, excellent toughness, transparency and heat resistance, and additionally having a high melt tension can be obtained with a reaction time less than a half of the conventional process. The copolymer obtained by the invention is a material suited for injection molding, extrusion, calendaring, blow forming, balloon forming, vacuum forming and foaming. Particularly, the copolymer obtained by the invention has a high melt tension and thus the molten copolymer is difficult to sag and flow and can be processed with ease into foams and blow bottles.

Abstract: A process for decomposing a thermoplastic polymer composition which comprises a polyhydroxycarboxylic acid base polymer as a primary component in an alkaline solution, recovering hydroxycarboxylic acid from the solution by electrodialysis or acid-precipitation and using the recovered hydroxycarboxylic acid for a polymer material, when desired, is provided.

Abstract: Formed products such as foams, fabrics for industrial materials, filaments, nonwoven fabrics, composite materials and films which are degradable after use with ease in the natural environment are prepared by using a high molecular weight aliphatic polyester obtained by direct polycondensation of an aliphatic polyhydric alcohol with aliphatic polybasic acid or additionally hydroxycarboxylic acid or oligomers of these materials in a reaction mixture containing a solvent.

Abstract: A lactic acid polymer composition comprising formulating 100 parts by weight of a mixture consisting of 80-95% by weight of an L-lactic acid polymer having an L-lactic acid proportion of 75% or more and 5-20% by weight of a plasticizer selected from the group consisting of a polyhydric alcohol ester and a hydroxypolycarboxylic acid ester, 0.1-5 parts by weight of an anti-bloking agent having a SiO.sub.2 content of 90% or more and an average particle size of 7-50 nm, and 0.1-2 parts by weight of a slip agent; a molded product and film obtained from the composition; and a preparation process of the same are disclosed. The molded product and film are excellent in processability, transparency, flexibility, anti-blocking property and slip, and can be degraded into harmless water and carbon dioxide under natural environment, when abandoned.

Abstract: A bioabsorbable, ternary block copolymer consisting essentially of (A) polylactic acid segment, (B) poly(.epsilon.-caprolactone) segment and (C) polyglycolic acid segment, preparation process of the block copolymer, and medical molded articles prepared from said block copolymer. The bioabsorbable block copolymer is excellent in mechanical strength and flexibility and has moderate hydrolyzability and is especially utilized for a surgical monofilament suture.

Abstract: Formed products such as foams, fabrics for industrial materials, filaments, nonwoven fabrics, composite materials and films which are degradable after use with ease in the natural environment are prepared by using a high molecular weight aliphatic polyester obtained by direct polycondensation of an aliphatic polyhydric alcohol with aliphatic polybasic acid or additionally hydroxycarboxylic acid or oligomers of these materials in a reaction mixture containing a solvent.

Abstract: A preparation process of heat-resistant molded articles of a lactic acid-based polymer comprising mixing the lactic acid-based polymer and poly-.epsilon.-caprolactone so as to obtain a L-lactic acid ratio of 75% by weight or more, adding to the polymer mixture a crystalline inorganic powder containing 50% by weight or more of SiO.sub.2, melt-kneading the resultant composition, filling the same into a mold which is set at 85.degree..about.125.degree. C. and forming a shape while promoting crystallization. The molded articles have excellent heat resistance and impact strength, are suitably used for food trays and beverage cups, and can be degraded, in the case of waste, into nontoxic water and carbon dioxide like natural products within a relatively short period in the natural environment.

Abstract: The invention is a purification process of an aliphatic polyester prepared in the presence of a catalyst from a hydroxycarboxylic acid or a cyclic ester of a hydroxycarboxylic acid, or a combination of an aliphatic polyhydric alcohol with an aliphatic polybasic acid, or a mixture of these compounds, comprising deactivating the catalyst while maintaining the aliphatic polyester in a molten or dissolved state, or insolubilizing and separating the catalyst and successively removing low molecular compounds; and can provide aliphatic polyester which has a low content of unreacted monomers and low molecular weight compounds and is excellent in heat resistance and weatherability.

Abstract: A process for preparing a degradable copolymer of aliphatic polyester comprising the steps of reacting two or more kinds of aliphatic polyester homopolymer in the presence of a catalyst in a reaction mixture containing an organic solvent, and a degradable copolymer of aliphatic polyester obtained by said preparation process. The copolymers exhibits high transparency in addition to excellent strength and elongation, can be processed into various molded articles and formed items such as films and filaments, and can provide heat resistance by heat treatment of said molded articles and formed items. The copolymer can be suitably utilized for processed articles such as a film, breathable film, sheet, textile, monofilament, multifilament, yarn, non-woven fabric, flat yarn, staple, crimped fiber, ribbed tape, split yarn, conjugate fiber, laminate, blow-bottle, sheet, stretched sheet, foam and net.

Abstract: The invention is a method of dyeing aliphatic polyester filaments with a disperse dye by selecting a dyeing temperature, dyeing pH, and dyeing time in such a way that the weight average molecular weight of the aliphatic polyester filament has a lowering ratio of 20% or less.The invention is a method for dyeing the aliphatic polyester filament with good reproducibility and level dyeing property while substantially maintaining the molecular weight and the essential excellent properties of the aliphatic polyester filament, and can provide dyed articles which have high strength, are excellent in level dyeing property and color fastness to light, and have various hues.

Abstract: A polymer containing the following monomer unit (I) and/or (II): ##STR1## and a process for preparing the polymer which comprises, in ring opening reaction of the polysuccinimide, opening the ring of polysuccinimide by using an amino acid ester having an extremely high reactivity in place of an .alpha.-amino acid having an extremely low reactivity. The polymer is characterized by having no irritation to organisms (e.g., eyes and skin), and for example, the polymer is useful in the industrial fields of fields of medical supplies, health, beauty and sanitary aids, quasi-pharmaceuticals, and the like.

Abstract: A multilayer composite consisting of aluminum and a resin composition primarily comprising a lactic acid base polymer, is disclosed. The composite material is excellent in mechanical and gas barrier properties and has characteristic of totally decomposing under alkaline conditions.

Abstract: A process for preparing a novel superabsorbent polymer which is readily hydrolyzed and conform to environment by reacting a polysuccinimide with a diamine in an aqueous solution or an organic solvent to partially crosslink the polysuccinimide, and subsequently or concurrently hydrolyzing the remaining imide ring with an alkali while controlling the pH; and the superabsorbent polymer thus obtained.

Abstract: A purification process of an aliphatic polyester prepared in the presence of a catalyst from a hydroxycarboxylic acid or a cyclic ester of a hydroxycarboxylic acid, or a combination of an aliphatic polyhydric alcohol with an aliphatic polybasic acid, or a mixture of these compounds, comprising deactivating the catalyst while maintaining the aliphatic polyester in a molten or dissolved state, or insolubilizing and separating the catalyst and successively removing low molecular compounds. The process can provide aliphatic polyester which has a low content of unreacted monomers and low molecular weight compounds and is excellent in heat resistance and weatherability.

Abstract: In the process for preparing polysuccinimide by dehydration condensation of aspartic acid in an organic solvent, polysuccinimide can be obtained simply and suitably in industry by removing a portion or more of the organic solvent from the reaction mixture while charging to the reaction mixture an additional organic solvent containing less amount of water than that of the removed organic solvent.

Abstract: A process for preparing a novel superabsorbent polymer which is readily hydrolyzed and conform to environment by reacting a polysuccinimide with a diamine in an aqueous solution or an organic solvent to partially crosslink the polysuccinimide, and subsequently or concurrently hydrolyzing the remaining imide ring with an alkali while controlling the pH; and the superabsorbent polymer thus obtained.

Abstract: Foams comprising innumerable cells dispersed in thermoplastic polymer compositions substantially consisting of polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid and having degradable characteristics in the natural environment.The foams can be used for containers such as food trays and throw away cups comprising molded sheet foam of a thermoplastic and degradable polymer or heat insulating materials and cushioning materials comprising bulk foam.

Abstract: A degradable polymer composition essentially consisting of a mixture of a thermoplastic polymer composition primarily comprising polylactic acid or lactic acid-hydroxycarboxylic acid copolymer and one or more substance selected from starch and modified starch, and is a degradable polymer which does not cause problems such as environmental pollution and can be used for films, filaments and packaging materials, food packaging materials in particular.

Abstract: A laminate comprising a thermoplastic polymer essentially consisting of polylactic acid, a copolymer of lactic acid and hydroxycarboxylic acid or a mixture of polylactic acid with a copolymer of lactic acid and hydroxycarboxylic acid, and a regenerated cellulose film, paper, leather, cloth, or fiber. The laminate undergoes degradability in the natural environment, is excellent in transparency, gloss and moisture-proofness, has high strength and can be used for various packaging materials.

Abstract: A preparation process of aliphatic polyester having a weight average molecular weight of 15,000 or more by conducting a direct polycondensation reaction of an aliphatic polyhydric alcohol or a mixed aliphatic polyhydric alcohol and an aliphatic polybasic acid or a mixed aliphatic polybasic acid, or additionally a hydroxycarboxylic acid or a mixed hydroxycarboxylic acid or an oligomer of the hydroxycarboxylic acid in a reaction mixture containing an organic solvent.The aliphatic polyester thus obtained contains an extremely small amount of impurities, has low color and can exhibit satisfactory strength in the form of films, filaments and other shaped articles.