Mitsubishi Kasei Corporation

Takamitsu Morita

Junya Watanabe

Shintaro Sawada

Toyokazu Sugawara

A method for preparing an ultrapure water, from which impurities including inorganic salts, organic substances, fine particles and microorganisms are removed, by treatment including an ion exchange treatment, which comprises using an ion exchange resin comprising a copolymer of a polyvinyl compound and a monovinyl aromatic compound which may contain a monovinyl aliphatic compound, as the matrix, at least in a mixed bed ion exchange treatment of the ion exchange treatment, said ion exchange resin used comprising at least a regenerated form ion exchange resin A eluting an organic compound of a molecular weight of less than 3,000 but substantially not eluting an organic compound of a molecular weight of not less than 3,000 when dipped in a hot water at 50.degree. C. for 7 days.

Method for preparing ultrapure water

A process for producing an ion exchange resin having a specific surface area of at least 0.04 m.sup.2 /g, an ion exchange resin produced by the process, and a method for removing ionic and noinionic impurities from a condensate by means of the ion exchange resin produced by the process. The process comprises the steps of: (1) uniformly imbibing a monomer mixture comprising a bifunctional unsaturated aromatic monomer and a monofunctional unsaturated aromatic monomer into aromatic crosslinked copolymer particles comprising a monofunctional unsaturated aromatic monomer and a bifunctional unsaturated aromatic monomer and having a porosity of not more than 0.2 ml/g; (2) polymerizing the monomer mixture in the presence of a polymerization initiator; and (3) introducing an ion exchange group into the resulting copolymer particles. The ion exchange resin has a large specific surface area and high physical strength and is capable of removing both ionic and noinionic impurities from a condensate.

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Kanagawa, Japan

Takamitsu Morita