Abstract: It is a problem of the present invention to provide a normal pressure cationic dyeable polyester being cationic dyeable under normal pressure, and having high strength. The problem can be solved by a normal pressure cationic dyeable polyester, characterized by being a copolymerized polyester having a main repeating unit including ethylene terephthalate, and including, in an acid component forming the copolymerized polyester, a metal salt of sulfoisophthalic acid (A) and a compound (B) which is a phosphonium salt of sulfoisophthalic acid or the like in such a state as to simultaneously satisfy the two mathematical expressions. Preferably, the glass transition temperature of the copolymerized polyester is within the range of 70 to 85° C., and the intrinsic viscosity of the copolymerized polyester is within the range of 0.55 to 1.00 dL/g. Further, by melt spinning the copolymerized polyester, it is possible to provide a polyester fiber.

Abstract: It is a problem of the present invention to provide a normal pressure cationic dyeable polyester being cationic dyeable under normal pressure, and having high strength. The problem can be solved by a normal pressure cationic dyeable polyester, characterized by being a copolymerized polyester having a main repeating unit including ethylene terephthalate, and including, in an acid component forming the copolymerized polyester, a metal salt of sulfoisophthalic acid (A) and a compound (B) which is a phosphonium salt of sulfoisophthalic acid or the like in such a state as to simultaneously satisfy the two mathematical expressions. Preferably, the glass transition temperature of the copolymerized polyester is within the range of 70 to 85° C., and the intrinsic viscosity of the copolymerized polyester is within the range of 0.55 to 1.00 dL/g. Further, by melt spinning the copolymerized polyester, it is possible to provide a polyester fiber.

Abstract: A major object of the invention is to provide such a method for extracting slurry that is not inhibited in extraction of slurry by a released and accumulated matter or a solid matter sedimented and accumulated at the bottom of the vessel. The invention relates to a method for extracting slurry by extracting slurry from an agitation vessel having a bottom face and a side wall and housing the slurry, characterized in that the slurry is extracted from an open end of a slurry extraction tube provided at the side wall of the agitation vessel. More preferably, a normal line direction of a surface of the open end is in a direction of an angle with respect to a downstream direction of a flow of the slurry caused by agitation of 0° or more and less than 90°.

Abstract: A through process comprising depolymerization reaction of used PET bottles with EG, recovering DMT by ester interchange reaction with MeOH, obtaining terephthalic acid by hydrolysis of the recovered DMT, and manufacturing a PET polymer which can be used for manufacturing PET bottles again by using the terephthalic acid.

Abstract: A through process comprising depolymerization reaction of used PET bottles with EG, recovering DMT by ester interchange reaction with MeOH, obtaining terephthalic acid by hydrolysis of the recovered DMT, and manufacturing a PET polymer which can be used for manufacturing PET bottles again by using the terephthalic acid.

Abstract: A major object of the invention is to provide such a method for extracting slurry that is not inhibited in extraction of slurry by a released and accumulated matter or a solid matter sedimented and accumulated at the bottom of the vessel. The invention relates to a method for extracting slurry by extracting slurry from an agitation vessel having a bottom face and a side wall and housing the slurry, characterized in that the slurry is extracted from an open end of a slurry extraction tube provided at the side wall of the agitation vessel. More preferably, a normal line direction of a surface of the open end is in a direction of an angle with respect to a downstream direction of a flow of the slurry caused by agitation of 0° or more and less than 90°.

Abstract: A through process comprising depolymerization reaction of used PET bottles with EG, recovering DMT by ester interchange reaction with MeOH, obtaining terephthalic acid by hydrolysis of the recovered DMT, and manufacturing a PET polymer which can be used for manufacturing PET bottles again by using the terephthalic acid.