Abstract: A method for producing a polyurethane elastic fiber according to the present invention contains the steps of: [1] producing a polyurethane urea polymer (A) having a number average molecular weight ranging from 12,000 to 50,000, and represented by general formula (1); [2] preparing a spinning dope by adding the polyurethane urea polymer (A) to a polyurethane urea polymer (B); and [3] spinning a polyurethane elastic fiber using the spinning dope. In the formula, R1 and R2 are an alkyl group or a hydroxyalkyl group, R3 is an alkylene group, a polyethyleneoxy group or a polypropyleneoxy group, R4 is a diisocyanate residue, X is a urethane bond or a urea bond, R5 and R6 are a diisocyanate residue, P is a diol residue, Q is a diamine residue, UT is a urethane bond, UA is a urea bond, each of k, 1, m and n is 0 or a positive number.

Abstract: A method for producing a polyurethane elastic fiber according to the present invention contains the steps of: [1] producing a polyurethane urea polymer (A) having a number average molecular weight ranging from 12,000 to 50,000, and represented by general formula (1); [2] preparing a spinning dope by adding the polyurethane urea polymer (A) to a polyurethane urea polymer (B); and [3] spinning a polyurethane elastic fiber using the spinning dope. In the formula, R1 and R2 are an alkyl group or a hydroxyalkyl group, R3 is an alkylene group, a polyethyleneoxy group or a polypropyleneoxy group, R4 is a diisocyanate residue, X is a urethane bond or a urea bond, R5 and R6 are a diisocyanate residue, P is a diol residue, Q is a diamine residue, UT is a urethane bond, UA is a urea bond, each of k, 1, m and n is 0 or a positive number.

Abstract: A method for producing a polyurethane elastic fiber according to the present invention contains the steps of: [1] producing a polyurethane urea polymer (A) having a number average molecular weight ranging from 12,000 to 50,000, and represented by general formula (1); [2] preparing a spinning dope by adding the polyurethane urea polymer (A) to a polyurethane urea polymer (B); and [3] spinning a polyurethane elastic fiber using the spinning dope. In the formula, R1 and R2 are an alkyl group or a hydroxyalkyl group, R3 is an alkylene group, a polyethyleneoxy group or a polypropyleneoxy group, R4 is a diisocyanate residue, X is a urethane bond or a urea bond, R5 and R6 are a diisocyanate residue, P is a diol residue, Q is a diamine residue, UT is a urethane bond, UA is a urea bond, each of k, l, m and n is 0 or a positive number.

Abstract: The antioxidant according to the present invention contains a polyurethane compound represented by the following formula (1): (wherein Y1 is a residue of a diol, and plural Y1s may be the same or different, R1 is a residue of an aromatic diisocyanate, and plural R1s may be the same or different, X1 is a residue of a hindered phenol compound having at least k hindered phenolic hydroxyl groups, and plural X1s may be the same or different, m is an integer of 1 or more, n is an integer of 1 or more, and k is an integer of 2 or more).

Abstract: A method for producing a polyurethane elastic fiber according to the present invention contains the steps of: [1] producing a polyurethane urea polymer (A) having a number average molecular weight ranging from 12,000 to 50,000, and represented by general formula (1); [2] preparing a spinning dope by adding the polyurethane urea polymer (A) to a polyurethane urea polymer (B); and [3] spinning a polyurethane elastic fiber using the spinning dope. In the formula, R1 and R2 are an alkyl group or a hydroxyalkyl group, R3 is an alkylene group, a polyethyleneoxy group or a polypropyleneoxy group, R4 is a diisocyanate residue, X is a urethane bond or a urea bond, R5 and R6 are a diisocyanate residue, P is a diol residue, Q is a diamine residue, UT is a urethane bond, UA is a urea bond, each of k, l, m and n is 0 or a positive number.

Abstract: The antioxidant according to the present invention contains a polyurethane compound represented by the following formula (1): (wherein Y1 is a residue of a diol, and plural Y1s may be the same or different, R1 is a residue of an aromatic diisocyanate, and plural R1s may be the same or different, X1 is a residue of a hindered phenol compound having at least k hindered phenolic hydroxyl groups, and plural X1s may be the same or different, m is an integer of 1 or more, n is an integer of 1 or more, and k is an integer of 2 or more).

Abstract: An elastic polyurethane fiber excellent in chlorine resistance, which contains particles of a metal compound selected from oxides and hydroxides of a metal selected from zinc and magnesium, and composite oxides of zinc and magnesium, a treating agent selected from a fatty acid, a styrene/maleic anhydride copolymer or its esterified products and a phosphoric ester adhering to the surface of the particles. The elastic polyurethane fiber is appropriate for an elastic fiber material for swimwear used in a swimming pool. The elastic polyurethane fiber can be produced by spinning a polyurethane spinning dope containing the metal compound particles to which such a specific treating agent as mentioned above adheres. The spinning dope suppresses secondary agglomeration of the metal compound particles and enables stabilized spinning of a modified polyurethane fiber.

Abstract: An elastic polyurethane fiber comprising, based on the fiber weight, from 0.5 to 10% by weight of composite oxide particles containing aluminium and at least one combination of zinc and magnesium selected from the group consisting of combinations of zinc and magnesium in respective specific ratios. The elastic polyurethane fiber has excellent chlorine resistance, and is suitable for swimwear for use in swimming pools. The elastic fiber can be obtained by spinning a polyurethane spinning dope containing, based on the polyurethane, from 0.5 to 10% by weight of the composite oxide particles. Filter clogging and yarn breakage caused by secondary agglomeration of the composite oxide particles are extremely decreased, and stabilized spinning can be conducted over a long period of time.

Abstract: A polyurethane composition excellent in chlorine resistance containing 0.1 to 10% by weight, based on the polyurethane, of hydrotalcite which has water of crystallization and a C.sub.10 -C.sub.30 fatty acid adhered thereto, capable of being stably spun over a long period of time, and exhibiting neither discoloration in the step of tannin solution treatment nor swelling during chlorine immersion treatment.