Abstract: Provided in this invention are polyethylene terephthalate resins which can suppress the formation of acetaldehyde as a by-product in melt molding of the resins and can provide the molded products reduced in acetaldehyde content. A polyethylene terephthalate resin which has an intrinsic viscosity [?2] of not less than 0.70 dl/g and not more than 1.50 dl/g and an acetaldehyde content [AA0 (ppm by weight)] of not more than 10 ppm by weight, and has such properties that the acetaldehyde content [AA1 (ppm by weight)] of the molded product obtained by injection molding the resin at 280° C. with its moisture content adjusted to 30±20 ppm by weight and the acetaldehyde content [AA2 (ppm by weight)] of the molded product obtained by injection molding the resin at 280° C. with its moisture content adjusted to 120±20 ppm by weight satisfy the following formula (1): [(AA1?AA2)/AA1]×100?30??(1).

Abstract: A process for producing a polyester using a catalyst, which catalyst enables producing a polyester excellent in color tone and transparency at a high reaction velocity; the catalyst; and a method for producing the catalyst, which catalyst comprises: (1) at least one metal element selected from the group consisting of metal elements of Group 4A of the Periodic Table, (2) at least one metal element selected from the group consisting of metal elements of Group 2A of the Periodic Table, aluminum, manganese, iron, cobalt, zinc, gallium and germanium, (a) when the total amount of metal atoms derived from metal element (1) is represented by t (mol/catalyst kg), and the total amount of metal atoms derived from metal element (2) is represented by m (mol/catalyst kg), the value of m/t is within 0.50?m/t?3.50.

Abstract: A polymerization catalyst for a polyester, characterized in that it comprises components having at least the following metal element (1) and the following metal element (2), their contents satisfy the following (a), it is in a liquid state with a turbidity of at most 20% in a light path length of 10 mm, and a polyester excellent in color tone and transparency can be produced at a high reaction velocity with it, a method for producing it and a process for producing a polyester using it: (1) at least one metal element selected from the group consisting of metal elements of Group 4A of the Periodic Table, (2) at least one metal element selected from the group consisting of metal elements of Group 2A of the Periodic Table, aluminum, manganese, iron, cobalt, zinc, gallium and germanium, (a) when the total amount of metal atoms derived from the above metal element (1) is represented by t (mol/catalyst kg), and the total amount of metal atoms derived from the above metal element (2) is represented by m (mol/catalyst

Abstract: Polymerization catalysts for polyesters include: (1) metal elements selected from metal elements of Group 4A of the Periodic Table; and (2) metal elements selected from metal elements of Group 2A of the Periodic Table, aluminum, manganese, iron, cobalt, zinc, gallium and germanium. The catalysts are in a liquid state with a turbidity of at most 20% in a light path length of 10 mm, and a ratio the total amount of metal atoms derived from the above metal element (2) to the total amount of metal atoms derived from the above metal element (1) is from 0.50 to 3.50.

Abstract: A polyester resin which is excellent in the color tone and the transparency, which has a low acetaldehyde content, and further, which is excellent also in the thermal stability and of which the increase in the acetaldehyde content during e.g. the melt molding is reduced, is provided.

Abstract: Provided in this invention are polyethylene terephthalate resins which can suppress the formation of acetaldehyde as a by-product in melt molding of the resins and can provide the molded products reduced in acetaldehyde content. A polyethylene terephthalate resin which has an intrinsic viscosity [?2] of not less than 0.70 dl/g and not more than 1.50 dl/g and an acetaldehyde content [AA0 (ppm by weight)] of not more than 10 ppm by weight, and has such properties that the acetaldehyde content [AA1 (ppm by weight)] of the molded product obtained by injection molding the resin at 280° C. with its moisture content adjusted to 30±20 ppm by weight and the acetaldehyde content [AA2 (ppm by weight)] of the molded product obtained by injection molding the resin at 280° C.

Abstract: A polyester resin characterized in that the content of the copolymerized components other than the terephthalic acid component and the ethylene glycol component, is not more than 4 mol % based on the total dicarboxylic acid component, and when polyester resin is formed into a molded product, the molded product has a specific absorbance.

Abstract: A polyester resin produced by polycondensing a dicarboxylic acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as the main component and a diol component containing ethylene glycol as the main component in the presence of at least an antimony compound and a phosphorus compound, via an esterification reaction or an ester exchange reaction, which is characterized in that the amount of antimony eluted when immersed in hot water of 95° C. for 60 minutes in the form of particles having a number average particle weight of 24 mg, is not more than 1 ?g per 1 g of the polyester resin, as antimony atoms (Sb).

Abstract: A polyester resin, whereby a molded product excellent in a gas barrier property and also excellent in an ultraviolet shielding property, a color tone, etc., and which is particularly suitable for molding a bottle for e.g. a beverage required to have an aroma retention property, and further, a polyester resin, whereby the acetaldehyde content as a molded product is reduced to eliminate an influence over the taste, aroma, etc. of the content, and a process for its production, wherein the polycondensability is improved, are to be presented.

Abstract: A polyester resin characterized in that the content of the copolymerized components other than the terephthalic acid component and the ethylene glycol component, is not more than 4 mol % based on the total discarboxylic acid component, and when polyester resin is formed into a molded product, the molded product has a specific absorbance.

Abstract: A polymerization catalyst for a polyester, characterized in that it comprises components having at least the following metal element (1) and the following metal element (2), their contents satisfy the following (a), it is in a liquid state with a turbidity of at most 20% in a light path length of 10 mm, and a polyester excellent in color tone and transparency can be produced at a high reaction velocity with it, a method for producing it and a process for producing a polyester using it: (1) at least one metal element selected from the group consisting of metal elements of Group 4A of the Periodic Table, (2) at least one metal element selected from the group consisting of metal elements of Group 2A of the Periodic Table, aluminum, manganese, iron, cobalt, zinc, gallium and germanium, (a) when the total amount of metal atoms derived from the above metal element (1) is represented by t (mol/catalyst kg), and the total amount of metal atoms derived from the above metal element (2) is represented by m (mol/catalyst

Abstract: A polyester resin which is excellent in the color tone and the transparency, which has a low acetaldehyde content, and further, which is excellent also in the thermal stability and of which the increase in the acetaldehyde content during e.g. the melt molding is reduced, is provided.

Abstract: A polyester resin produced by polycondensing a dicarboxylic acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as the main component and a diol component containing ethylene glycol as the main component in the presence of at least an antimony compound and a phosphorus compound, via an esterification reaction or an ester exchange reaction, which is characterized in that the amount of antimony eluted when immersed in hot water of 95° C. for 60 minutes in the form of particles having a number average particle weight of 24 mg, is not more than 1 &mgr;g per 1 g of the polyester resin, as antimony atoms (Sb).

Abstract: A polyester resin produced by polycondensing a dicarboxylic acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as the main component and a diol component containing ethylene glycol as the main component in the presence of at least an antimony compound and a phosphorus compound, via an esterification reaction or an ester exchange reaction, which is characterized in that the amount of antimony eluted when immersed in hot water of 95° C. for 60 minutes in the form of particles having a number average particle weight of 24 mg, is not more than 1 &mgr;g per 1 g of the polyester resin, as antimony atoms (Sb).

Abstract: A polyester resin, whereby a molded product excellent in a gas barrier property and also excellent in an ultraviolet shielding property, a color tone, etc., and which is particularly suitable for molding a bottle for e.g. a beverage required to have an aroma retention property, and further, a polyester resin, whereby the acetaldehyde content as a molded product is reduced to eliminate an influence over the taste, aroma, etc. of the content, and a process for its production, wherein the polycondensability is improved, are to be presented.

Abstract: A polyester resin is prepared by polycondensing a dicarboxylic acid component containing terephthalic acid or its ester-forming derivative as the main component, and a diol component containing ethylene glycol as the main component in the presence of (1) a compound of at least one member selected from the group consisting of titanium group elements in Group 4A of the Periodic Table, via an esterification reaction or an ester exchange reaction, wherein the content of copolymerized components other than the terephthalic acid component and the ethylene glycol component, is not more than 4 mole % based on the total dicarboxylic acid component, and in a molded product with a thickness of 3.5 mm injection-molded at 280° C., the difference between the absorbance at a wavelength of 395 nm and the absorbance at a wavelength of 800 nm is at least 0.08, and the difference between the absorbance at a wavelength of 500 nm and the absorbance at a wavelength of 800 nm is at most 0.05.

Abstract: A polyester resin produced by polycondensing a dicarboxylic acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as the main component and a diol component containing ethylene glycol as the main component in the presence of at least an antimony compound and a phosphorus compound, via an esterification reaction or an ester exchange reaction, which is characterized in that the amount of antimony eluted when immersed in hot water of 95° C. for 60 minutes in the form of particles having a number average particle weight of 24 mg, is not more than 1 &mgr;g per 1 g of the polyester resin, as antimony atoms (Sb).

Abstract: A polyester resin characterized in that the content of the copolymerized components other than the terephthalic acid component and the ethylene glycol component, is not more than 4 mol % based on the total dicarboxylic acid component, and when polyester resin is formed into a molded product, the molded product has a specific absorbance.

Abstract: The present invention relates to a polyester resin produced by polymerizing a dicarboxylic acid component comprising mainly an aromatic dicarboxylic acid or its ester forming derivative, and a diol component comprising mainly ethylene glycol in the presence of a catalyst containing a titanium compound, which polyester resin contains titanium atoms (Ti) in an amount of 0.002 to 1.0 mole based on one ton of the polyester resin and has the following properties: Intrinsic viscosity ([&eegr;], dl/g)≧0.70 Hunter's “b” value≦4 Acetaldehyde content (AA0, ppm)≦5.0.

Abstract: Disclosed are a polyester mainly composed of an aromatic dicarboxylic acid as an acid component and an aliphatic diol as a diol component, wherein the content of an antimony element in the polyester is from 50 to 350 ppm, the number of metallic antimony particles having a diameter of 0.5 &mgr;m or more is 30,000 or more per 100 mg of polyester, the ratio of the number of fine particles having a diameter of 0.5 &mgr;m to less than 0.6 &mgr;m is 70% or more, and the L value in hue is 80 or more; a stretch blow molded product formed of the polyester; and a method for producing a polyester mainly composed of an aromatic dicarboxylic acid as an acid component and ethylene glycol as a diol component which comprises adding a preliminary mixed catalyst solution of an antimony compound and a trivalent phosphorus compound as a catalyst, the catalyst solution having a haze of 10% or less, at a stage showing an acid value of 1,000 eq/ton or less before initiation of melt polymerization.