Abstract: A random-block copolymer having appropriate hydrolyzability, excellent flexibility and excellent mechanical strength, a monofilament thereof, and a process for producing the copolymer. The random-block copolymer comprises from 5 to 50 mol % of a random copolymer segment containing from 20 to 80 mol % of a lactide unit (A) and from 80 to 20 mol % of a caprolactone unit (B), and from 95 to 50 mol % of a block copolymer segment containing a glycolide unit (C).

Abstract: Articles matters which can be degraded and disappear in the natural environment are a degradable adhesive film which can be used for surface protection or indication after printing on the film surface and has an adhesive layer on one side of a substrate film obtained from a lactic acid base polymer such as polylactic acid and a lactic acid/hydroxycarboxylic acid copolymer having a molecular weight of 30,000.about.500,000, and a degradable resin composition which is excellent in weatherability and comprises 100 parts by weight of a lactic acid base polymer and 0.001.about.5 parts by weight of one or more additives selected from ultraviolet absorbers and light stabilizers.

Abstract: Articles which can be degraded and disappear in the natural environment are a degradable adhesive film which can be used for surface protection or indication after printing on the film surface and has an adhesive layer on one side of a substrate film obtained from a lactic acid base polymer such as polylactic acid and a lactic acid/hydroxycarboxylic acid copolymer having a molecular weight of 30,000-500,000, and a degradable resin composition which is excellent in weatherability and comprises 100 parts by weight of a lactic acid base polymer and 0.001-5 parts by weight of one or more additives selected from ultraviolet absorbers and light stabilizers.

Abstract: A degradable non-woven fabric obtained from an web formed of lactic acid-based polymer filaments comprising of one or more lactic acid-based polymers selected from a poly (DL-lactic acid) having more than 80 mol % of L-lactic acid units, poly (DL-lactic acid) having more than 80 mol % of D-lactic acid units, L-lactic acid/hydroxycarboxylic acid copolymer having 70 mol % or more of L-lactic acid units, and D-lactic acid/hydroxycarboxylic acid copolymer having 70 mol % or more of D-lactic acid units, and a preparation process of the degradable non-woven fabric which has good dimensional stability and can be degraded and disappeared under natural environment when abandoned.

Abstract: In the preparation of polyester by conducting ring-opening polymerization of a cyclic ester compound in the presence of a hydroxyl compound as a molecular weight regulator in the reaction system, the molecular weight of polyester can be accurately controlled in the desired range by previously estimating the amount of free carboxylic acid contained in the cyclic ester compound and controlling the amount of the hydroxyl compound on the basis of the estimated amount.