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 herein is technology relating to polymerization and producing polymers and particularly, but not exclusively, to methods, systems, and compositions for producing articles using three-dimensional printing and for improving control of polymerization using a polymerization photoinhibitor having fast back reaction kinetics such as hexaarylbiimidazole compounds and bridged hexaarylbiimidazole compounds.

Provided herein is technology relating to polymerization and producing polymers and particularly, but not exclusively, to methods, systems, and compositions for producing articles using three-dimensional printing and for improving control of polymerization using a polymerization photoinhibitor having fast back reaction kinetics such as hexaarylbiimidazole compounds and bridged hexaarylbiimidazole compounds.

The present disclosure relates to a (meth)acrylate adhesive composition comprising a (meth)acrylated polymer, a crosslinking agent and a silane copolymer, wherein the silane copolymer comprises 70 to 95 weight parts of an acrylate monomer containing C.sub.1-C.sub.4 alkyl group and 5 to 30 weight parts of a silane represented by the following formula (I):

X—R.sup.1—SiR.sup.2.sub.3-a(OR.sup.3).sub.a  (I)

wherein the weight-average molecular weight of the silane copolymer is ranging from 40,000 to 150,000. The silane copolymer can enhance the initial adhesion strength, rework ability and weather resistance of the (meth)acrylate adhesive composition. Furthermore, the (meth)acrylate adhesive composition can be used in the flexible optical film with a good bending restoring property and adhesion.

Provided is a polymerization initiator, which has an excellent curing rate and is an alternative to a polymerization initiator system using a benzoyl peroxide-aromatic amine compound, a curable composition containing the polymerization initiator, a dental material and dental filler material containing the composition, and a kit for preparing the curable composition. The polymerization initiator contains one or more compounds (A) selected from the group consisting of a pyrazolidinedione compound and/or pyrazolidine(di)thione compound (A1), a salt (A2) of the compound (A1), and a malonate compound (A3).

A conductive material dispersion containing a conductive material containing carbon fibers, a dispersant, and a dispersion medium, in which the dispersant contains a copolymer A containing a nitrile group-containing structural unit and an aliphatic hydrocarbon structural unit, and a Mooney viscosity (ML.sub.1+4, 100° C.) of the copolymer A is 40 to 70, and the conductive material dispersion has a phase angle of 19° or greater at a frequency of 1 Hz.

A conductive material dispersion containing a conductive material containing carbon fibers, a dispersant, and a dispersion medium, in which the dispersant contains a copolymer A containing a nitrile group-containing structural unit and an aliphatic hydrocarbon structural unit, and a Mooney viscosity (ML.sub.1+4, 100° C.) of the copolymer A is 40 to 70, and the conductive material dispersion has a phase angle of 19° or greater at a frequency of 1 Hz.

A method for producing a polyvinylphosphonic acid copolymer may control a rise in internal temperature in the reaction system during polymerization and may allow synthesis of a copolymer as a polymer solution. A method for producing a polyvinylphosphonic acid copolymer may include polymerizing a compound of formula (1) and a compound of formula (2) in presence of a radical polymerization initiator and in a water-containing solvent: ##STR00001## wherein R.sup.1 and R.sup.2 are independently —OH, —O.sup.−, or —O.sup.−M.sup.+ (M.sup.+ being a counter ion), R.sup.3 is —OH, —O.sup.−, —O.sup.−M.sup.+, or an optionally substituted alkoxy group having 1 to 10 carbon atoms (M.sup.+ being a counter ion), and R.sup.4 is an optionally substituted alkoxy group having 1 to 10 carbon atoms, R.sup.3 and R.sup.4 optionally forming a ring together with an adjacent phosphorus atom when both R.sup.3 and R.sup.4 are alkoxy groups.

A method for producing a polyvinylphosphonic acid copolymer may control a rise in internal temperature in the reaction system during polymerization and may allow synthesis of a copolymer as a polymer solution. A method for producing a polyvinylphosphonic acid copolymer may include polymerizing a compound of formula (1) and a compound of formula (2) in presence of a radical polymerization initiator and in a water-containing solvent: ##STR00001## wherein R.sup.1 and R.sup.2 are independently —OH, —O.sup.−, or —O.sup.−M.sup.+ (M.sup.+ being a counter ion), R.sup.3 is —OH, —O.sup.−, —O.sup.−M.sup.+, or an optionally substituted alkoxy group having 1 to 10 carbon atoms (M.sup.+ being a counter ion), and R.sup.4 is an optionally substituted alkoxy group having 1 to 10 carbon atoms, R.sup.3 and R.sup.4 optionally forming a ring together with an adjacent phosphorus atom when both R.sup.3 and R.sup.4 are alkoxy groups.

A conductive material dispersion containing a conductive material containing carbon fibers, a dispersant, and an amide-based organic solvent, in which the dispersant contains a copolymer A containing a nitrile group-containing structural unit and satisfies following conditions. (I) A pH of the conductive material dispersion is 9.0 or greater. (II) A phase angle of the conductive material dispersion at a frequency of 1 Hz obtained by dynamic viscoelasticity measurement is 19° or greater, and a complex elastic modulus of the conductive material dispersion obtained by dynamic viscoelasticity measurement is less than 20 Pa.