Abstract: A method for producing a high molecular weight aliphatic polyester, wherein:(A) 100 parts by weight of polyester (a) with a number average molecular weight of at least 10,000, and a weight average molecular weight of at least 30,000, and with end-groups that are substantially hydroxyl groups, and with a melting point of at least 60.degree. C., the polyester (a) having been obtained by reacting the following three ingredients: (i) a glycol ingredient; (ii) an aliphatic dicarboxylic acid ingredient; and (iii) a trifunctional or tetrafunctional ingredient reacts with(B) 0.1-3 parts by weight of a poly-isocyanate in a melted state of the polyester (a).The method provides a high molecular weight aliphatic polyester which has good properties and a melt viscosity required for molding and forming and has a wide molecular weight distribution. The high molecular weight aliphatic polyester is applicable to a variety of fields, such as films, moldings and formings, fibers, etc.

Abstract: An unsaturated alkyd having a number-average molecular weight of at least 5000 and having terminal carboxyl groups is provided by esterification and then deglycolization reaction of an .alpha.,.beta.-unsaturated polybasic acid or an polyhydroxy alcohol followed by reaction with polybasic acid anhydride to substitute more than 10 mole % of terminal hydroxyl groups with carboxyl groups. High molecular weight unsaturated polyester resin is also provided by formulating the unsaturated alkyd with a copolymerizable monomer such as styrene. The polyester resin can be widely used in a various applications by employing the excellent physical properties thereof.

Abstract: A method for manufacturing a biodegradable high molecular weight aliphatic polyester. This method comprises the steps of: [A] synthesizing an aliphatic polyester having a number average molecular weight of at least 5,000 and/or a weight average molecular weight of at least 30,000 by reacting aliphatic or alicyclic glycol with aliphatic dicarboxylic acid or its anhydride, applying a 0.001-0.5 part by weight of organic or inorganic metallic compound as a catalyst with respect to 100 parts by weight of aliphatic polyester to be produced; [B] adding a 0.01-3 parts by weight of organic or inorganic phosphorus compound with respect to 100 parts by weight of aliphatic polyester upon completion of the reaction; and [C] reacting a 0.1-5 parts by weight of polyvalent isocyanate compound with 100 parts by weight of the aliphatic polyester so that the polyester has a number average molecular weight of at least 10,000 and/or a weight average molecular weight of at least 50,000.

Abstract: An unsaturated alkyd having a number-average molecular weight of at least 5000 obtained by esterification and then deglycolization reaction of (a) at least 10 mol % of an .alpha., .beta.-unsaturated polybasic acid or an anhydride thereof relative to 100 mol % of the total polybasic acid including any saturated or non-.alpha., .beta.-unsaturated polybasic acid (or anhydride thereof) and (b) at least 50 mol % of a polyhydroxy alcohol having a boiling point of 300.degree. C. or less at 760 mmHg relative to 100 mol % of the total polyhydroxy alcohol summed up with another polyhydroxy alcohol not defined above. The polyester resin can be widely used in a various applications by employing the excellent physical properties thereof.