To provide a thickener having excellent performances by establishing a technique of increasing the molecular weight of a (meth)acrylate polymer without detriment to its water solubility.
This thickener contains as an effective component a high- molecular-weight low-water-insolubles-content (meth)acrylate polymer obtained by mixing a polymerizable reactant solution containing at least 60mol%, based on the polymerizable monomer, (meth)acrylic acid with 60-120mol%, based on the entire acid groups in the solution, at least one type of ions selected from the group consisting of alkali metal ions and ammonium ions and 0.01-20wt.%, based on the polymerizable monomer, water-soluble compound selected from the group consisting of ethylene glycol, propylene glycol, glycerol, monosaccharides, sugar alcohols, oligosaccharides and polyvinyl alcohols having a degree of saponification of 70% or above and subjecting the resulting mixture to aqueous solution polymerization in a quiescent state.
SHIOJI NAOTAKE
TSUBOI HIROSHI
