Abstract: To provide a biaxially stretched polyester resin film that has excellent properties equal to or better than those of biaxially stretched polyester film that does not use recycled raw material, and in particular that has an excellent flexural resistance in low-temperature environments. A biaxially stretched polyester resin film that characteristically satisfies both of the following properties (1) and (2): (1) in differential scanning calorimetry (DSC), after heating from 25° C. to 300° C. at a heating rate of 20° C./minute and holding for 10 minutes at 300° C., the temperature of crystallization during cooling at a cooling rate of 40° C./minute is 160° C. to 180° C.; and (2) the number of pinholes after the execution of 200 repetitive cycles of a flexural fatigue test in a ?10° C. atmosphere using a Gelbo Flex Tester is not more than 10/500 cm2.

Abstract: A polyester resin comprises a dicarboxylic acid component and a glycol component, wherein the glycol component contains ethylene glycol together with diethylene glycol and triethylene glycol, and a content of triethylene glycol in the glycol component is more than 0.1 mol % and 5.5 mol % or less.

Abstract: A resin composition includes a copolymerized polyester resin, which exhibits excellent flexibility at room temperature, improvement in problems of brittleness, and excellent adhesiveness and moist-heat durability. The invention relates to a resin composition containing a copolymerized polyester resin which contains, as an acid component, an aromatic dicarboxylic acid and a dimer acid and, as a glycol component 1,4-butane diol and polybutadiene glycols, with the content of the dimer acid being 10 to 50 mol % in the acid component, the content of the 1,4-butane diol being 50 mol % or greater in the glycol component, and the content of the polybutadiene glycols being 0.5 to 20 mol % in the glycol component.

Abstract: A process for producing a polyester film is disclosed, which comprises melt-mixing from 3 to 12 parts by weight of a master polymer comprising a poly(alkylene terephthalate) which contains from 0.3 to 3 wt % inorganic lubricant and has an intrinsic viscosity of 0.5 or higher with from 97 to 88 parts by weight of a poly(alkylene terephthalate) containing no inorganic lubricant and having an intrinsic viscosity of 0.5 or higher, and forming the resulting mixture into a film by the electrostatic casting method. The master polymer is obtained by a process comprising adding to a poly(alkylene terephthalate) oligomer having an average degree of polymerization of 10 or lower an alkylene glycol slurry of an inorganic lubricant and specific amounts of a potassium compound and a phosphorus compound, depolymerizing the oligomer, subsequently adding specific amounts of antimony trioxide and germanium dioxide, and then effecting polycondensation.

Abstract: a resin composition for a powder coating comprising a polyester A, which does not substantially set to gel and has a hydroxyl value of at least 1,200 g eq/10.sup.6 g, a polyester B, which does not substantially set to gel and has a hydroxyl value of from 200 to 1,000 g eq/10.sup.6 g, and an inner blocked isocyanate hardener, wherein the weight ratio of polyester A to polyester B is from 70:30 to 10:90 and the difference (absolute value) in gel time between these polyesters A and B is at least 3 minutes.

Abstract: A resin composition for powder coating which comprises a substantially un-gelled polyester A having a hydroxyl value of from 1,200 to 5,000 g eq/10.sup.6 g, a substantially un-gelled polyester B having a hydroxyl value of from 200 to 1,000 g eq/10.sup.6 g, tetramethoxymethyl glycoluril as a curing agent and an organic sulfonic acid compound as a curing catalyst, wherein the weight ratio of polyester A to polyester B is from 70:30 to 10:90 and the difference (absolute value) in the gel time between polyester A and polyester B is at least 3 minutes.

Abstract: A resin composition for powder coating which comprises a substantially un-gelled polyester A having an acid value of from 1,200 to 5,000 g eq/10.sup.6 g, a substantially un-gelled polyester B having an acid value of from 200 to 1,000 g eq/10.sup.6 g and triglycidyl isocyanurate as a curing agent, wherein the weight ratio of polyester A to polyester B is from 70:30 to 10:90 and the difference (absolute value) in the gel time between polyester A and polyester B is at least 3 minutes.A resin composition for powder coating which causes no problems of polluting a baking oven, which shows less weight loss at the time of reaction and which can form a semi-mat or completely mat stable paint film is provided. These advantages cannot be obtained from any prior art powder coating that comprises a polyester having a large quantity of terminal hydroxyl groups and a blocked isocyanate-based curing agent.

Abstract: A resin composition for a matte powder coating comprising a polyester A having a hydroxyl value of at least 1,200 g eq/10.sup.6 g, a polyester B having a hydroxyl value of from 200 to 1,000 g eq/10.sup.6 g and a blocked isocyanate hardener, wherein the weight ratio of polyester A to polyester B is from 70:30 to 10:90, the difference (absolute value) in gel time between polyester A and polyester B is at least 3 minutes and the difference (absolute value) in acid value between these polyesters is at least 20 g eq/10.sup.6 g is disclosed.

Abstract: A flame resistant polyester produced by addition and copolymerization of a phosphorus compound represented by general formula (I) below as a diol component of the polyester in an amount of 500 ppm or more in terms of phosphorus atom content in the polyester, which polyester has alkylene terephthalate units as main repeating units and which has an intrinsic viscosity of not less than 0.5 measured at 20.degree. C. in a mixture of equal weight of phenol and tetrachloroethane: ##STR1## where E is --CH.sub.2 CH.sub.2 --, Ar is an aromatic group or an aromatic group substituted by a lower alkyl group or a halogen atom, and m and n denote, respectively, integers the sum of which is from 1 to 20.

Abstract: A polyester, wherein pendent phosphorus atoms are bound to the main chain of the polyester, having an excellent flame resistance and a high intrinsic viscosity can be stably produced without deteriorating the properties of said polyester by preliminarily copolymerizing a polyester with a specific unsaturated compound and then reacting the unsaturated bond thus-formed with a specific phosphorus compound having a P-H bond.

Abstract: A random copolyester is described, comprising recurring moieties represented by formula (I), (II), and (III), and having an intrinsic viscosity of not less than 0.5, wherein said recurring moieties of formulae (I) and (II) are existing substantially in equimolar amount and recurring moieties of formulae (I) and (III) are present in a molar ratio of from 95/5 to 5/95 ##STR1## wherein Ar.sub.1 represents a trivalent aromatic group and Ar.sub.2 represents a divalent aromatic group. In formulae (I), (II), and (III), aromatic rings may be substituted with an alkyl group or an alkoxy group having from 1 to 20 carbon atoms, an aryl group or aryloxy group having from 6 to 20 carbon atoms, or a halogen atom. The copolyester obtained is excellent in heat resistance and flame retardance.

Abstract: The present invention relates to a denier-mixed composite yarn containing 20 weight percent or more coarse filaments whose single filament fineness is 3 deniers or more and 5 weight percent or more fine filaments whose single filament fineness is 1.5 denier or less. Part or all of the coarse filaments are of non-circular cross-section, the stress of the composite yarn at 10% elongation is 2.5 g/d or less, and the composite yarn has a particular distribution of elongation. According to such denier-mixed composite yarn, superior dry feel fullness and softness can be imparted to woven and knit fabrics.

Abstract: In a process for continuously producing polyester which comprises continuously polymerizing bis-.beta.-hydroxyethyl terephthalate and/or a lower polymer thereof using a plurality of vacuum polymerization reactors equipped with a stirrer disposed in series, the improvement which comprises automatically and continuously measuring stirring power or stirring axis reaction force of at least the final polymerization reactor among the polymerization reactors from which a polymer having a limiting viscosity (.eta.) of 0.25 or more is removed, and controlling the vacuum in the polymerization reactors based on changes in the stirring power or reaction force so that the stirring power or reaction force is kept at a prescribed level, by which the degree of polymerization of the polymer removed from the polymerization reactors is controlled. A process for producing a polyester spun fiber is also disclosed.

Abstract: A heat-curable resin composition obtained by mixing (A) a polyester resulting from the depolymerization of a polyester of a high degree of polymerization comprising an aromatic dicarboxylic acid and an aliphatic dialcohol using a compound containing about 2 to about 12 carboxyl groups per molecule with (B) a polyoxirane compound containing about 2 to about 100 oxirane groups per molecule. A heat-curable resin composition obtained by adding to the above resin composition a salt formed between an aliphatic monocarboxylic acid containing 2 to 20 carbon atoms and an element of Group II of the Periodic Table as a curing accelerator is an especially superior material for powder paints. Powder paints prepared from these heat-curable resin compositions provide coatings having superior appearance and properties upon baking after coating by a method such as an electrostatic spray coating method or a fluidized dip coating method.

Abstract: A polyester resin composition suitable for preparing a powder paint, obtained by mixing a polyester, which is obtained by depolymerizing a polyester having a high degree of polymerization with an intrinsic viscosity of about 0.4 or more with at least one of a substantially nonvolatile alcohol and an ester having at least one alcoholic hydroxyl group in the same molecule, melts at a temperature between about 45.degree. C and about 120.degree. C and has terminal hydroxyl groups and an average degree of polymerization ranging from about 5 to about 50, with a polyisocyanate blocked with an alkyl p-hydroxybenzoate by melting. The polyester resin composition can be readily pulverized, has no blocking property and has the fluidity at relatively low temperatures sufficient to facilitate pigmentation, and can form beautiful coatings. The coatings have good resistance to weathering, solvents, humidity and fouling, and excellent adhesion to a metal.

Abstract: A polyester resin composition obtained by mixing a molten polyester having an average degree of polymerization ranging from about 5 to 50 mainly comprising a terephthalic acid unit, a p-hydroxybenzoic acid unit and an ethylene glycol unit, and one hardener selected from the group consisting of a diglycidyl compound, hexaalkoxymethylmelamine or the condensate thereof, and a blocked isocyanate, with the composition being suitable for the preparation of a powder paint. The thus produced polyester resin composition can be finely pulverized with ease, shows no blocking property, facilitates pigmentation and provides beautiful coatings excellent in weather resistance, solvent resistance, humidity resistance, antifouling property, and with intimate adhesiveness to metal.