To produce a novel flocculant not causing a problem such as waste water treatment difficulty and environmental pollution and to produce a solid grain having a hydrophilic group on its surface and capable of easily forming a highly stable oil-in-water emulsion only by adding water.
This hydrophilic solid grain consists of a hot-melt water-soluble solid grain and a surfactant having a hydrophilic group and a hydrophobic group, and the surfactant is bonded to the solid grain through the hydrophobic group. A molten water-insoluble material is granulated in water in the presence of a surfactant to form an oil-in-water emulsion, the emulsion is cooled to convert the molten grain of the water-insoluble material into the solid grain, and the solid grain is separated from water to produce the hydrophilic grain.
OKI TATSUYA
ARAI SATOSHI
SAKAMOTO HIROSHI
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