Water-insoluble, swellable polyurethanes

Claim 1

A lightly cross-linked, water-insoluble, swellable, polyurethane, network polymer comprising a cross-linked network of polymer segments consisting essentially of from 1 to 90% by weight of hydroxyl-terminated hydrophilic polyether chain segments, the remainder being hydroxyl-terminated oleophilic hydrocarbon polymer chain segments, a trihydroxy, organic cross-linking agent in an amount less than one cross-link for every 4,000 chain atoms of the network polymer and a substantially stoichiometric amount of diisocyanate curing agent, said segments containing no less than 25 backbone chain atoms and said polymer being in the form of particles having a diameter of no more than 1 mm, a swellability of no less than 2, an absorptivity on a dry basis of polar organic compounds of at least 10 percent, and a cross-link density of no more than one cross-link for every 4,000 backbone chain atoms.

Claim 10

A method of synthesizing a lightly cross-linked, water-insoluble network polymer having a swellability of no less than 2, an absorptivity on a dry basis of polar organic compounds of no less than 10, and a cross-link density of no more than one cross-link for every 4,000 backbone chain atoms comprising the steps of: forming a mixture of 1-75% by weight of hydroxyl-terminated polyether hydrophilic polymeric chain segments having at least 25 chain atoms in each segment and the remainder being hydroxyl-terminated oleophilic hydrocarbon polymeric chain segments containing at least 25 carbon atoms per segment; adding a trihydroxy organic cross-linking agent in an amount less than one cross-link for every 4,000 chain atoms of the final network polymer to said mixture and allowing said mixture to react with a substantially stoichiometric amount of a diisocyanate curing agent to form cross-links between said chain segments such that the swellability of the final polymer is at least 2 and the absorptivity is at least 10 percent; and removing the non-cross-linked soluble portion from said polymer by solvent extraction.

Claim 11

A method of synthesizing a lightly cross-linked, water-insoluble network polymer having a swellability of no less than 2, an absorptivity on a dry basis of polar organic compounds of no less than 10, and a cross-link density of no more than one cross-link for every 4,000 backbone chain atoms comprising the steps of: forming a mixture of 1-75% by weight of hydroxyl-terminated polyether hydrophilic polymeric chain segments having at least 25 chain atoms in each segment and the remainder being hydroxyl-terminated oleophilic hydrocarbon polymeric chain segments containing at least 25 carbon atoms per segment; adding a trihydroxy organic cross-linking agent in an amount less than one cross-link for every 4,000 chain atoms of the final network polymer to said mixture and allowing said mixture to react with a substantially stoichiometric amount of a diisocyanate curing agent to form cross-links between said chain segments such that the swellability of the final polymer is at least 2 and the absorptivity is at least 10 percent; and removing the non-cross-linked soluble portion from said polymer by solvent extraction.