Abstract: A breathable, hydrolyzable, porous film having long-term stability in mechanical properties which is obtained by the process comprising adding from 40 to 250 parts by weight of a finely-powdered filler having an average particle size of from 0.3 to 4 .mu.m to 100 parts by weight of a polylactic acid-based resin composition comprising from 80 to 95% by weight of polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and from 5 to 20% by weight of a plasticizer comprising a citric acid ester, melting and film-forming the resultant mixture, and successively stretching the thus-obtained film 1.1 times or more at least in the direction of the axis; and which is consequently useful as a material for leakproof films of sanitary materials such as a paper diaper and packaging materials, and does not accumulate as wastes because of hydrolyzability in the natural environment in the case of being abandoned after use.

Abstract: A breathable, hydrolyzable, porous film which is obtained by the process comprising adding from 40 to 250 parts by weight of a finely-powdered filler having an average particle size of from 0.3 to 4 .mu.m to 100 parts by weight of a polylactic acid-based resin composition comprising from 80 to 100% by weight of polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and from 0 to 20% by weight of a plasticizer, melting and film-forming the resultant mixture, and successively stretching the thus-obtained film 1.1 times or more at least in the direction of the axis; and which is consequently useful as a material for leakproof films of sanitary materials such as a paper diaper and packaging materials, and does not accumulate as wastes because of hydrolyzability in the natural environment in the case of being abandoned after use.

Abstract: A degradable polymer network obtained by adding from 0.2 to 10 parts by weight of a foaming agent to 100 parts by weight of a polylactic acid-base resin composition comprising from 80 to 100% by weight of polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and from 0 to 20% by weight of a plasticizer, conducting melt-foaming extrusion of resulting mixture, and opening the foam cells in the extrudate. The high polymer network is characterized in suitable flexibility and hydrolyzability and thus useful as a material for absorbing of oils and body fluids, screens for sunlight, heat-insulating materials, filter media and packaging materials; and does not accumulate as industrial wastes because of hydrolyzability in the natural environment, even though abandoned after use.

Abstract: A degradable polymer network obtained by adding from 0.2 to 10 parts by weight of a foaming agent to 100 parts by weight of a polylactic acid-base resin composition comprising from 80 to 100% by weight of polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and from 0 to 20% by weight of a plasticizer, conducting melt-foaming extrusion of resulting mixture, and opening the foam cells in the extrudate. The high polymer network is characterized in suitable flexibility and hydrolyzability and thus useful as a material for absorbing oils and body fluids, screens for sunlight, heat-insulating materials, filter media and packaging materials; and does not accumulate as industrial wastes because of hydrolyzability in the natural environment, even though abandoned after use.