The Dow Chemical Company

Natalie N Westphal

Robert M Strom

William I Harris

Suresh Subramonian

Kenneth L Foster

Antonio Dorta

Robert E Gaidos

Cation exchange resins are prepared by sulfonating copolymer beads in the presence of a swelling solvent under pressure. Pressure sulfonation shortens cycle times and requires less energy while maintaining or improving product quality.

Manufacture of cation exchange resins by pressurized sulfonation

A process is provided for preparing ion-exchange resin particles of relatively uniform size by partial functionalization of non-uniform copolymer beads with ion-exchange groups. The non-uniform copolymer beads are preferably functionalized in a manner such that the ion-exchange groups are substituted at available sites which are most accessible to diffusion by functionalizing agents. Due to the size difference between individual copolymer particles, a greater proportion of available sites is functionalized in a small particle when compared to that of a large particle. Due to the greater proportion of ion-exchange groups present in a small particle, the small particle swells relatively more than a larger particle. The result is effectively a narrowing of the size distribution for the partially functionalized resin particles. The relatively uniform resin particles obtained by the process have performance advantages, such as reduced pressure drops, improved exchange kinetics, rinse efficiencies, and separation efficiencies when compared to fully functionalize ion-exchange resins that are non-uniform in particle size.

Method of preparing uniform size ion exchange resin particles by partial

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Auburn, MI, United States of America

Natalie N Westphal