Abstract: A polyester having a good color tone (a high L value and a low b value) and a low acetaldehyde content is obtained by using a catalyst containing a reaction product of (A) a titanium compound (1) represented by the general formula (I) and/or a titanium compound (2) obtained by reacting the titanium compound (1) of the general formula (I) with an aromatic polyhydric carboxylic acid represented by the general formula (II) or an anhydride thereof, with (B) a phosphorus compound (3) represented by the general formula (III). [wherein R1, R2, R3, R4 and R5=a C2-C10 alkyl group, k=1 to 3, m=2 to 4, and R6=a substituted or non-substituted C6-C20 aryl group or a C6-C20 alkyl group].

Abstract: A poly(ethylene aromatic dicarboxylate ester) resin usable for the production of fibers, films and bottle-formed articles, is produced by polycondensing a diester of an aromatic dicarboxylic acid with ethylene glycol by using a catalyst including a non-reacted mixture or reaction product of a titanium compound component including at least one member selected from titanium alkoxides and reaction products of the titanium alkoxides with aromatic polyvalent carboxylic acids or anhydrides thereof, with a specific phosphorus compound, in which catalyst the contents of titanium and phosphorus elements are controlled.

Abstract: A poly(ethylene aromatic dicarboxylate ester) resin usable for the production of fibers, films and bottle-formed articles, is produced by polycondensing a diester of an aromatic dicarboxylic acid with ethylene glycol by using a catalyst including a non-reacted mixture or reaction product of a titanium compound component including at least one member selected from titanium alkoxides and reaction products of the titanium alkoxides with aromatic polyvalent carboxylic acids or anhydrides thereof, with a specific phosphorus compound, in which catalyst the contents of titanium and phosphorus elements are controlled.

Abstract: A polyester having a good color tone (a high L value and a low b value) and a low acetaldehyde content is obtained by using a catalyst containing a reaction product of (A) a titanium compound (1) represented by the general formula (I) and/or a titanium compound (2) obtained by reacting the titanium compound (1) of the general formula (I) with an aromatic polyhydric carboxylic acid represented by the general formula (II) or an anhydride thereof, with (B) a phosphorus compound (3) represented by the general formula (III).

Abstract: A biaxially oriented polyester film to be laminated on a metal plate and molded, which comprises an aromatic polyester composition comprising: (A) an aromatic polyester which comprises ethylene terephthalate as the main recurring unit and a titanium compound and a phosphorus compound both of which satisfy at least one of the following expressions (1) and (2): 0.1≦Ti/P≦3.0  (1) 5≦Ti+P≦60  (2) wherein Ti is the amount (mmol %) of elemental titanium of the titanium compound contained in this aromatic polyester and P is the amount (mmol %) of elemental phosphorus of the phosphorus compound contained in the aromatic polyester, and the following expression (3): 2≦Ti≦20  (3) wherein Ti is as defined hereinabove, and which contains alkali metal compounds, germanium compound and antimony compound in a total amount of not more than 3 ppm in terms of the total of elemental alkali metals, elemental germanium and elemental antimony; and (B) 0.05 to 5.

Abstract: A biaxially oriented polyester film for magnetic recording media improved in slipperiness, shaving resistance and scratch resistance by protrusions formed on the film surface, namely, a polyester film for magnetic recording media wherein the film is a biaxially oriented polyester film which contains (I) heat resistant high molecular particles having an average particle size of 0.3 to 1.5 .mu.m in 0.001 to 0.5% by weight of the polyester, and(II) alumina particles having an independent existence rate of 80% or more and an average particle size of 0.06 to 0.2 .mu.m in 0.05 to 1.0% by weight of the polyester and/or colloidal silica particles having an independent existence rate of 80% or more and an average particle size of 0.3 .mu.m or less in 0.05 to 2.0% by weight of the polyester;wherein the distribution curve, in the range where the height (x : .mu.m) is 0.05 .mu.m or more and the number of the protrusions (y : per mm.sup.2) is 30 protrusions/mm.sup.

Abstract: A biaxially oriented polyester film formed from an aromatic polyester composition containing:(A) 100 parts by weight of an aromatic polyester, and(B) 0.005 to 5 parts by weight of calcium carbonate particles defined by:(a) a length/width ratio (2a/2b) in the range of from 1.25 to 3,(b) an average particle diameter (D), as a diameter of a circle converted from an area, in the range of from 0.05 to 5 .mu.m, and(c) an ellipse coefficient, represented by the following equation (1), in the range of from 0.7 to 1.2, ##EQU1## wherein R is an ellipse coefficient, S.sub.1 is an observed area of a projected plane of a particle, and S.sub.2 is an elliptical area determined on the basis of observed values of the length (2a) and width (2b);and a magnetic recording medium formed of the above biaxially oriented polyester film and a magnetic layer formed thereon.