To provide a method for crystallizing an isomer of a polyisocyanate by feeding a mixture of isomers of the polyisocyanate to a crystallizer to shorten a time for crystallization and separating the isomer while keeping the quality and the yield of the separated isomer.
The crystallizer has a crystallizing tube body arranged so as to be opened in the feeding direction of the mixture of the isomers of the aromatic polyisocyanate, and having a nearly tube shape, and at least one tube for crystallization arranged in the interior of the crystallization tube body so as to be opened in the feeding direction of the mixture of the isomers of the aromatic polyisocyanate, and having a nearly tube shape. The tube for the crystallization has contacting plates arranged in the interior thereof so as to be parallel to the longitudinal direction of the tube for the crystallization. The isomer of the aromatic polyisocyanate is crystallized in the interior of the tube for the crystallization by feeding the mixture of the isomers of the aromatic polyisocyanate to the tube for the crystallization of the crystallization tube body of the crystallizer.
SAEKI TAKUYA
Koji Makimura
Chihata Takahata
Toru Suzuki
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