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US 4,399,235 AGranted
High density ion exchange resins
AssigneeThe Dow Chemical Company
InventorsCharles F. Raley, Jr., Edward R. Husser
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AssigneeThe Dow Chemical Company
InventorsCharles F. Raley, Jr., Edward R. Husser
Estimating the term…
High density, ion exchange resins having excellent integrity are prepared from cross-linked, aromatic polymers which have been halogenated in the presence of an organic liquid having a sufficiently high dielectric constant to prevent substantial halogenation of the polymer backbone such as various organic nucleophiles having a free electron pair associated with a nonhalogen atom, e.g., ethanol or dimethylformamide. For example, a cross-linked polystyrene which has been brominated in methylene chloride containing a small amount of ethanol can subsequently be chloromethylated and aminated to form a high density anion exchange resin useful in removing anions from thick slurries such as those employed in uranium recovery.
A method for preparing an ion exchange resin, said method comprising the steps of (a) contacting a cross-linked polymer of a monovinylidene aromatic with a halogenating agent in the presence of an organic liquid compound having a dielectric constant sufficiently high to prevent substantial halogenation of the polymeric backbone, said contact being conducted at conditions sufficient to halogenate the polymer and using amounts of the halogenating agent sufficient to increase the density of the polymer and (b) attaching ion-active exchange groups to the halogenated, cross-linked polymer.
A method for preparing an ion exchange resin, said method comprising the steps of (a) contacting a cross-linked polymer of a monovinylidene aromatic, a halogenating agent and an organic nucleophile having a free electron pair associated with a nonhalogen atom and a dielectric constant sufficiently high to prevent substantial amounts of halogenation of the backbone, said contact being conducted at conditions sufficient to halogenate the polymer and using amounts of the halogenating agent sufficient to increase the density of the cross-linked aromatic polymer and (b) subsequently attaching ion-active exchange groups to the halogenated, cross-linked polymer.
A method for preparing an ion exchange resin, said method comprising the steps of (a) contacting a cross-linked polymer of a monovinylidene aromatic with a halogenating agent in a bulk reaction diluent of an organic liquid compound having a dielectric constant from about 8 to 11, said contact being conducted at conditions sufficient to halogenate the polymer and using amounts of halogenating agent sufficient to increase the density of the polymer and (b) subsequently attaching ion-active exchange groups to the halogenated, cross-linked polymer.
Dependencies are inferred from the claim text.