| abstract |
(57) [PROBLEMS] To obtain a water-in-oil emulsion coagulant of a water-soluble vinyl polymer having a sufficient drainage improving effect and having good stability over time. SOLUTION: A water-soluble vinyl copolymer (a1), water (b), a hydrocarbon liquid containing 2-acryloyloxyethyldimethylbenzylammonium chloride (A1) and another vinyl monomer (A2) as an essential constituent unit. A water-in-oil emulsion containing (c) and a surfactant (d) as essential components, wherein the content of (c) in the emulsion is 10 to 40% by weight, and the emulsion has a wavelength of 600 nm. A coagulant having a light transmittance of 60% or more. |