Abstract: A process for producing an aliphatic polyester resin composition, wherein an aliphatic polyester resin is melt-kneaded with a phosphoric acid ester having a reduced moisture content of 1.5 wt. % or less. As a result, an aliphatic polyester resin composition having an improved moisture resistance is provided.

Abstract: A polyglycolic acid resin composition having improved moisture resistance is obtained by adding a carboxyl group-capping agent and a polymerization catalyst-deactivation agent to a polyglycolic acid resin.

Abstract: A particulate polyglycolic acid resin composition, comprising: a blend of a first particulate polyglycolic acid resin and a second particulate polyglycolic acid resin each having a moisture content of at most 110 ppm and providing a ratio of melt-viscosity (as measured at 270° C. and a shear rate of 121 sec?1; the same as hereinafter) therebetween of above 1 and at most 10. After the polymerization, the first and second particulate polyglycolic acid resins can cause change in properties before the forming (e.g., during storage); or during the forming process. However, by adequately determining the blending ratio between the resins while taking the melt-viscosities thereof into account, it becomes possible to provide a particulate polyglycolic acid resin composition showing a stable melt-formability and suitable as a starting material for various forming processes.

Abstract: A process for producing an aliphatic polyester resin composition, wherein an aliphatic polyester resin is melt-kneaded with a phosphoric acid ester having a reduced moisture content of 1.5 wt. % or less. As a result, an aliphatic polyester resin composition having an improved moisture resistance is provided.

Abstract: A method for producing a solid polyglycolic acid-based resin composition, including a cooling step of cooling a polyglycolic acid-based resin composition in a molten state by an aqueous medium, wherein in the cooling step, the polyglycolic acid-based resin composition in the molten state is cooled by being brought into contact with the aqueous medium so that a sodium ion concentration in an obtained solid polyglycolic acid-based resin composition can be less than 100 ppb by mass.

Abstract: A low melt viscosity polyglycolic acid having a melt viscosity of at most 100 Pa·s as measured at a temperature higher by 10° C. than the melting point of the polyglycolic acid and a shear rate of 122 sec?1, a temperature at 3%-weight loss on heating of at least 280° C. and a water content of at most 500 ppm, and being in a solid state at a temperature of 20±15° C., and a production process of the low melt viscosity polyglycolic acid including a water vapor absorption step and a heat treatment step for a high melt viscosity polyglycolic acid being in a solid state.

Abstract: A particulate polyglycolic acid resin composition suitable as a material for various forming processes in produced through a process characterized by comprising: cooling a polyglycolic acid resin composition having a residual glycolide content of at most 0.6 wt. % in a molten state by contact with an aqueous cooling medium to solidify the composition, and pelletizing the composition.

Abstract: A polyglycolic acid resin composition having improved moisture resistance is obtained by adding a carboxyl group-capping agent and a polymerization catalyst-deactivation agent to a polyglycolic acid resin.

Abstract: An aliphatic polyester improved provided by using water positively as an initiator or/and a molecular weight-adjusting agent, is improved in moisture resistance. More specifically, a cyclic ester containing proton-source compounds including more than 80 ppm of water as an initiator or/and a molecular weight-adjusting agent, is subjected to ring-opening polymerization, and the resultant aliphatic polyester is compounded with a carboxyl group-capping agent to produce such an aliphatic polyester.

Abstract: Ring-opening polymerization of a cyclic ester is performed by using an alcohol and water positively as initiators or/and molecular weight-adjusting agents to control the initial properties and properties with time of the resultant aliphatic polyester. More specifically, an aliphatic polyester is produced by ring-opening polymerization of a cyclic ester containing water and an alcohol based on a total proton concentration and a ratio between a mol concentration of carboxyl (carboxylic acid)-source compounds including water and a mol concentration of alkoxycarbonyl (ester)-source compounds, as polymerization-controlling indexes.

Abstract: A particulate polyglycolic acid resin composition, comprising: a blend of a first particulate polyglycolic acid resin and a second particulate polyglycolic acid resin each having a moisture content of at most 110 ppm and providing a ratio of melt-viscosity (as measured at 270° C. and a shear rate of 121 sec?1; the same as hereinafter) therebetween of above 1 and at most 10. After the polymerization, the first and second particulate polyglycolic acid resins can cause change in properties before the forming (e.g., during storage); or during the forming process. However, by adequately determining the blending ratio between the resins while taking the melt-viscosities thereof into account, it becomes possible to provide a particulate polyglycolic acid resin composition showing a stable melt-formability and suitable as a starting material for various forming processes.

Abstract: A particulate polyglycolic acid resin composition suitable as a material for various forming processes in produced through a process characterized by comprising: cooling a polyglycolic acid resin composition having a residual glycolide content of at most 0.6 wt. % in a molten state by contact with an aqueous cooling medium to solidify the composition, and pelletizing the composition.

Abstract: For producing an aliphatic polyester resin composition containing a thermal stabilizer and a carboxyl group-capping agent, the aliphatic polyester resin is first mixed in a hot-melt state with the thermal stabilizer and then mixed in a hot-melt state with the carboxyl group-capping agent. As a result thereof, the resultant aliphatic polyester resin composition is provided with better moisture resistance and noticeably improved heat resistance (less coloring) than in the case where these additives are simultaneously added to effect the hot-melt mixing.

Abstract: For producing an aliphatic polyester resin composition containing a thermal stabilizer and a carboxyl group-capping agent, the aliphatic polyester resin is first mixed in a hot-melt state with the thermal stabilizer and then mixed in a hot-melt state with the carboxyl group-capping agent. As a result thereof, the resultant aliphatic polyester resin composition is provided with better moisture resistance and noticeably improved heat resistance (less coloring) than in the case where these additives are simultaneously added to effect the hot-melt mixing.

Abstract: Ring-opening polymerization of a cyclic ester is performed by using an alcohol and water positively as initiators or/and molecular weight-adjusting agents to control the initial properties and properties with time of the resultant aliphatic polyester. More specifically, an aliphatic polyester is produced by ring-opening polymerization of a cyclic ester containing water and an alcohol based on a total proton concentration and a ratio between a mol concentration of carboxyl (carboxylic acid)-source compounds including water and a mol concentration of alkoxycarbonyl (ester)-source compounds, as polymerization-controlling indexes.

Abstract: An aliphatic polyester improved provided by using water positively as an initiator or/and a molecular weight-adjusting agent, is improved in moisture resistance. More specifically, a cyclic ester containing proton-source compounds including more than 80 ppm of water as an initiator or/and a molecular weight-adjusting agent, is subjected to ring-opening polymerization, and the resultant aliphatic polyester is compounded with a carboxyl group-capping agent to produce such an aliphatic polyester.

Abstract: Styrene based resin compositions comprise a styrene resin and a graft copolymer obtained by graft-polymerizing, in the presence of a butadiene based rubbery polymer, a monomer mixture composed of a monomer containing 1-50 ethylene oxide groups and one ethylenically-unsaturated bond and styrene or a monomer mixture compound of styrene as a principal component and at least one monomer copolymerizable with styrene. The a styrene based resin compositions are obtained by blending the graft copolymer with a styrene resin and having excellent impact strength and visual properties.