Abstract: This invention provides a polyester and a polyester molded product, which, while maintaining color tone, transparency, and thermal stability, can realize a high polycondensation rate, are less likely to cause the production of polycondensation catalyst-derived undesired materials, and can simultaneously meet both quality and cost effectiveness requirements, which can exhibit the characteristic features, for example, in the fields of ultrafine fibers, high transparent films for optical use, or ultrahigh transparent molded products. These advantages can be realized by using, in the production of a polyester in the presence of an aluminum compound-containing polyester polycondensation catalyst, an aluminum compound having an absorbance of not more than 0.0132 as measured in the form of an aqueous aluminum compound solution, prepared by dissolving the aluminum compound in pure water to give a concentration of 2.

Abstract: The present invention relates to such a polyamide resin composition that is suitably used as a material of a gasoline tank and a material of a molded article, such as a hollow molded container including a beverage bottle, a film and a sheet. A polyamide resin that is good in heat stability upon molding and suffers less increase in filter back pressure is provided by regulating a polyamide resin composition to have a phosphorus content of from 30 to 200 ppm (excluding 200 ppm), and a sodium content/phosphorus content ratio (molar ratio) of from 3 to 7 (excluding 3 and 7) or regulating it to have a phosphorus content less than 30 ppm and an alkali metal content less than 45 ppm.

Abstract: This invention provides a polyester and a polyester molded product, which, while maintaining color tone, transparency, and thermal stability, can realize a high polycondensation rate, are less likely to cause the production of polycondensation catalyst-derived undesired materials, and can simultaneously meet both quality and cost effectiveness requirements, which can exhibit the characteristic features, for example, in the fields of ultrafine fibers, high transparent films for optical use, or ultrahigh transparent molded products. These advantages can be realized by using, in the production of a polyester in the presence of an aluminum compound-containing polyester polycondensation catalyst, an aluminum compound having an absorbance of not more than 0.0132 as measured in the form of an aqueous aluminum compound solution, prepared by dissolving the aluminum compound in pure water to give a concentration of 2.

Abstract: The present invention relates to such a polyamide resin composition that is suitably used as a material of a gasoline tank and a material of a molded article, such as a hollow molded container including a beverage bottle, a film and a sheet. A polyamide resin that is good in heat stability upon molding and suffers less increase in filter back pressure is provided by regulating a polyamide resin composition to have a phosphorus content of from 30 to 200 ppm (excluding 200 ppm), and a sodium content/phosphorus content ratio (molar ratio) of from 3 to 7 (excluding 3 and 7) or regulating it to have a phosphorus content less than 30 ppm and an alkali metal content less than 45 ppm.

Abstract: The invention provides a polyester produced in the presence of a polycondensation catalyst comprising at least one compound selected from a group consisting of aluminum compounds and at least one compound selected from a group consisting of phosphorus compounds and being excellent in color tone, thermal stability, and transparency and improved in terms of insoluble particles. Particularly, the invention provides a polyester in which the content of an aluminum containing insoluble particles in the polyester is 3500 ppm or lower and a polyester which has a haze value of 2% or lower when being formed into a monoaxially oriented film. The aluminum catalyst for attaining these characteristics and properties may be polyester polymerization catalyst obtained by mixing an aluminum compound and a phosphorus compound in a solvent and has specified spectral characteristics in the side measurement of 31P-NMR spectrum and 27Al-NMR spectrum.