Abstract: A film-formable high molecular polyetherpolyester comprising structural unit (1) of formula (1) and functional group (2) of formula (2) and having a number-average molecular weight of 40,000 to 10,000,000, wherein the molar ratio of functional group (2) to R in the polyetherpolyester is in the range of 1.0 to 3.0. This polyetherpolyester can be produced by carrying out a chain extension reaction of a low molecular polyalkylene oxide of 1,000 to 30,000 in number-average molecular weight with a polyvalent acid anhydride at 0.003 MPa or higher in a molar ratio of (acid anhydride group)/(hydroxyl group)=0.8 to 1.0.

Abstract: A heat exchanger washing apparatus comprises a hopper for accommodating a plurality of washing brushes, a first heat exchanger leading guide having a first guide passage for guiding the washing brushes, a first opening/closing member for opening and closing the first guide passage, a first stopper disposed to the first guide passage, a second stopper, an air introduction passage communicating with the connecting port of the first guide passage downstream of the portion thereof where the first opening/closing member is disposed, a second opening/closing member for opening and closing the air introduction passage, a second heat exchanger leading guide connected to the first guide passage downstream of the connecting port and having a second guide passage for guiding the washing brushes with the extreme end of the second guide passage serving as an inserting portion which will be inserted into the pipe of a heat exchanger, first stopper control means, second stopper control means, first opening/closing control m

Abstract: A polyester resin composition comprises: an aliphatic polyester having a number-average molecular weight (Mn) in a range of 10,000 to 100,000; and a crystalline nucleating agent, wherein the aliphatic polyester and the crystalline nucleating agent are mixed in such that a half value width of an exothermic peak based on an annealing crystallization of the aliphatic polyester measured by differential scanning calorimetry in an atmosphere of nitrogen at a cooling rate of 3K/minute is not more than 15K. This polyester resin composition has a biodegradability and a high crystallization rate. The polyester resin composition also has excellent mechanical properties and eliminates a precise temperature control during a molding process which saves labor force resulting in desirable moldability and productivity. For the described beneficial properties, the polyester resin composition can be readily processed into a fiber, a molded article, sheet, film and the like.

Abstract: A method for producing an aliphatic polyester having a biodegradability and a higher melting point than conventional aliphatic polyester by suppressing a volatile component generated by side reaction or decomposition reaction with industrially good efficiency and economically in a relatively short period of time, the method enabling a polymerization at vacuum which permits a use of general vacuum pump. The aliphatic polyester can be obtained, for example, by a ring-opening copolymerization of a cyclic acid anhydride with a cyclic ether in a presence of a zirconium compound. The aliphatic polyester also can be obtained by performing a polymerization of raw materials of the aliphatic polyester so as to have a degree of viscosity in the range of 10-10,000 poise when 0.1-30 hours elapsed after the reaction started at reaction temperature of the reaction system under conditions of reaction temperature in the range of 180.degree. C. to 280.degree. C. and reaction pressure in the range of 0.3 mmHg to 3.0 mmHg.