An object of the present invention is to provide a PVA-based resin having a degree of saponification obtained in the middle stage of the reaction, that is, an average degree of saponification of 68 mol % to 85 mol %, a narrow degree of saponification distribution, and excellent dispersion stability. The present invention relates to a polyvinyl alcohol-based resin having an average degree of saponification of 68 mol % to 85 mol %, and a ¼ value width of 7.0 minutes or less in a degree of saponification distribution obtained by high performance liquid chromatogram measured under specific conditions.

An object of the present invention is to provide a PVA-based resin having a degree of saponification obtained in the middle stage of the reaction, that is, an average degree of saponification of 68 mol % to 85 mol %, a narrow degree of saponification distribution, and excellent dispersion stability. The present invention relates to a polyvinyl alcohol-based resin having an average degree of saponification of 68 mol % to 85 mol %, and a ¼ value width of 7.0 minutes or less in a degree of saponification distribution obtained by high performance liquid chromatogram measured under specific conditions.

Provided is a PVA-containing additive for oil well cement superior in fluid loss-reducing property. Specifically, provided is an additive for oil well cement, the additive containing polyvinyl alcohol having a saponification value of 75 to 85 mol % and a viscosity-average polymerization degree of 2,800 to 4,500. Also provided are a cement composition containing the additive for oil well cement in an amount of 0.01 to 30% bwoc and a cement slurry containing the additive for oil well cement in an amount of 0.01 to 30% bwoc.

The present invention discloses a photosensitive composition, comprising polyvinyl acetate (0% saponified) having a styryl type nitrogen-containing heterocyclic groups such as a styrylpyridinium or/and styrylquinolinium that possesses high UV light energy sensitivity with a small photosensitive group content, high solid content, high water resistance, and very sharp imaging characteristics and produced therefrom photosensitive compositions such as a photo-resist, photolithographic plates, screen printing stencil emulsion and film, and abrasion resistant photosensitive emulsion and film, and other photosensitive compositions being used for commercial and industrial applications.

The present invention discloses a photosensitive composition, comprising polyvinyl acetate (0% saponified) having a styryl type nitrogen-containing heterocyclic groups such as a styrylpyridinium or/and styrylquinolinium that possesses high UV light energy sensitivity with a small photosensitive group content, high solid content, high water resistance, and very sharp imaging characteristics and produced therefrom photosensitive compositions such as a photo-resist, photolithographic plates, screen printing stencil emulsion and film, and abrasion resistant photosensitive emulsion and film, and other photosensitive compositions being used for commercial and industrial applications.

The present invention provides a dispersion stabilizer for suspension polymerization that, when used for suspension polymerization of a vinyl compound, provides excellent polymerization stability, and can produce a vinyl polymer having a reduced number of coarse particles, and a reduced number of fisheyes when molded into a sheet form. The present invention also provides a method therewith. The present invention relates to a dispersion stabilizer for suspension polymerization of a vinyl compound, the dispersion stabilizer comprising a vinyl alcohol polymer (A) having a viscosity-average degree of polymerization of more than 400 and less than 1,000, a degree of saponification of more than 67 mol % and less than 78 mol %, 0.02 mol % to 1.0 mol % of a group having an ethylenic double bond in its side chain, and an absorbance (x) at 280 nm of more than 0.17 and less than 0.65 in an ultraviolet absorption spectrum of a 0.1 mass % aqueous solution.

Embodiments of organic peroxide formulations provide longer scorch time protection and require fewer additives. The peroxide formulations may include, for example, at least one organic peroxide, at least one nitroxide-containing compound (e.g., 4-hydroxy-TEMPO), and at least one quinone-containing compound (e.g., mono-tert-butylhydroquinone).

Embodiments of organic peroxide formulations provide longer scorch time protection and require fewer additives. The peroxide formulations may include, for example, at least one organic peroxide, at least one nitroxide-containing compound (e.g., 4-hydroxy-TEMPO), and at least one quinone-containing compound (e.g., mono-tert-butylhydroquinone).

The present invention provides an industrially advantageous method for producing vinyl alcohol polymers having a low degree of polymerization using a chain transfer agent having an aliphatic hydrocarbon group having 6 to 12 carbon atoms, the method being capable of producing a vinyl alcohol polymer whose aqueous solution has excellent viscosity stability. The present invention relates to a method for producing vinyl alcohol polymers, including: polymerizing a vinyl ester monomer (a) in the presence of a polymerization initiator (B) and a chain transfer agent (C) having an aliphatic hydrocarbon group having 6 to 12 carbon atoms to obtain a vinyl ester polymer (A); and saponifying the vinyl ester polymer (A) at a concentration of 40 mass % or more and 75 mass % or less in the presence of an acidic catalyst (D) to obtain a vinyl alcohol polymer, wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization of 160 or more and 400 or less.

The present invention provides an industrially advantageous method for producing vinyl alcohol polymers having a low degree of polymerization using a chain transfer agent having an aliphatic hydrocarbon group having 6 to 12 carbon atoms, the method being capable of producing a vinyl alcohol polymer whose aqueous solution has excellent viscosity stability. The present invention relates to a method for producing vinyl alcohol polymers, including: polymerizing a vinyl ester monomer (a) in the presence of a polymerization initiator (B) and a chain transfer agent (C) having an aliphatic hydrocarbon group having 6 to 12 carbon atoms to obtain a vinyl ester polymer (A); and saponifying the vinyl ester polymer (A) at a concentration of 40 mass % or more and 75 mass % or less in the presence of an acidic catalyst (D) to obtain a vinyl alcohol polymer, wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization of 160 or more and 400 or less.