GB914421A - Improvements in or relating to cellulosic sponge material - Google Patents

Abstract

A cellulosic sponge material is treated with a reagent capable of reacting with the hydroxyl groups of the cellulose to provide groups attached to the cellulosic structure, which groups have inherently ion-exchange properties. An oxyacid of phosphorus, e.g. orthophosphoric acid, may be used to provide a phosphorylated cellulosic sponge material, the reaction conditions preferably being such as to provide a product having an ion-exchange capacity of 0,5-10 meq./g. Phosphorylation may be effected by saturating cellulose with a mixture of urea and orthophosphoric acid, squeezing out most of the reagent, curing the treated cellulose in an oven at 130 DEG C. for 2-3 hours, and then washing out unreacted reagent. Other reagents which may be used include citric acid yielding citrate groups attached to the cellulose, and mixtures of strong alkali with either (a) sodium chloroacetate, to yield carboxymethyl groups, (b) aminoethylsulphuric acid, to yield aminoethyl groups, (c) 2-chlorotriethylamine hydrochloride, to yield diethylaminoethyl groups, or (d) a mixture of epichlorhydrin and triethanolamine, to yield basic groups containing tertiary nitrogen. The cellulosic sponge material may be in block or sheet form and may contain scrim or fibrous reinforcing material. It may be prepared by rolling out a crystal paste of viscose and regenerating the viscose by conventional means. Materials so made have a high ion-exchange capacity and good structural rigidity, and liquids flow through such materials rapidly.ALSO:A cellulosic sponge material is treated with a reagent capable of reacting with the hydroxyl groups of the cellulose to provide groups attached to the cellulosic structure, which groups have inherently ion-exchange properties. An oxyacid of phosphorus, e.g. orthophosphoric acid, may be used to provide a phosphorylated cellulosic sponge material, the reaction conditions preferably being such as to provide a product having an ion-exchange capacity of 0,5-10 meq./g. Phosphorylation may be effected by saturating cellulose with a mixture of urea and othophosphoric acid, squeezing out most of the reagent, curing the treated cellulose in an oven at 130 DEG C. for 2-3 hours, and then washing out unreacted reagent. Other reagents which may be used include citric acid yielding citrate groups attached to the cellulose, and mixtures of strong alkali with either (a) sodium chloroacetate, to yield carboxymethyl groups, (b) aminoethylsulphuric acid, to yield aminoethyl groups, (c) 2-chlorotriethylamine hydrochloride, to yield diethyl aminoethyl groups, or (d) a mixture of epichlorhydrin and triethanolamine, to yield basic groups containing tertiary nitrogen. The cellulosic sponge material may be in block or sheet form and may contain scrim or fibrous reinforcing material. It may be prepared by rolling out a crystal paste of viscose and regenerating the viscose by conventional means. Materials so made have a high ion-exchange capacity and good structural rigidity, and liquids flow through such materials rapidly.