Abstract: The present invention relates to polyvinyl sulfonic acid comprising a vinyl sulfonic acid unit represented by a specific general formula (1), wherein the molar amount of sulfonic acid groups derived from vinyl sulfonic acid monomers with respect to the molar amount of total monomer units is 50.0 to 98.0 mol %, and the polyvinyl sulfonic acid has an absorbance of 0.1 or greater (aqueous solution: 0.2 mass %, cell length: 10 mm) in a wavelength range of 255 to 800 nm.

Abstract: (1) A vinyl sulfonic acid, having a double bond content of 95 wt. % or more, and (i) a sodium (Na) content of 1 ppm or less, and (ii) a content of at least one metal selected from the group consisting of alkali earth metal and first row transition metal of 1 ppm or less. Alternatively, (2) a vinyl sulfonic acid, having a double bond content of 95 wt. % or more, and (i) a sodium (Na) content of 100 ppb or less, and (ii) a content of at least one metal selected from the group consisting of alkali earth metal and first row transition metal of 100 ppb or less. Further, a homopolymer or copolymer thereof, a production method thereof, or a thin-film distillation apparatus suited for the production thereof.

Abstract: The present invention relates to polyvinyl sulfonic acid comprising a vinyl sulfonic acid unit represented by a specific general formula (1), wherein the molar amount of sulfonic acid groups derived from vinyl sulfonic acid monomers with respect to the molar amount of total monomer units is 50.0 to 98.0 mol %, and the polyvinyl sulfonic acid has an absorbance of 0.1 or greater (aqueous solution: 0.2 mass %, cell length: 10 mm) in a wavelength range of 255 to 800 nm.

Abstract: The subject invention provides: a method for producing vinyl sulfonic acid, comprising conducting demetallation of vinyl sulfonate salt, wherein the demetallation rate is not less than 95% according to the following formula: Demetallation rate(%)={(acid value after demetallation)/(acid value before demetallation)}×100; a method for producing vinyl sulfonic acid, comprising conducting demetallation of vinyl sulfonate salt, wherein demetallation is carried out using a strongly acidic ion exchange resin; and said method further comprising the step of purifying a product of the demetallation using a thin film evaporator.

Abstract: (1) A vinyl sulfonic acid, having a double bond content of 95 wt. % or more, and (i) a sodium (Na) content of 1 ppm or less, and (ii) a content of at least one metal selected from the group consisting of alkali earth metal and first row transition metal of 1 ppm or less. Alternatively, (2) a vinyl sulfonic acid, having a double bond content of 95 wt. % or more, and (i) a sodium (Na) content of 100 ppb or less, and (ii) a content of at least one metal selected from the group consisting of alkali earth metal and first row transition metal of 100 ppb or less. Further, a homopolymer or copolymer thereof, a production method thereof, or a thin-film distillation apparatus suited for the production thereof.

Abstract: The subject invention provides: a method for producing vinyl sulfonic acid, comprising conducting demetallation of vinyl sulfonate salt, wherein the demetallation rate is not less than 95% according to the following formula: Demetallation rate(%)={(acid value after demetallation)/(acid value before demetallation)}×100; a method for producing vinyl sulfonic acid, comprising conducting demetallation of vinyl sulfonate salt, wherein demetallation is carried out using a strongly acidic ion exchange resin; and said method further comprising the step of purifying a product of the demetallation using a thin film evaporator.