Method of preparing a membrane of divinyl benzene, styrene and maleic anhydride

Claim 1

A METHOD OF PREPARING A DIAPHRAGM FOR USE IN AN ELECTROLYTIC CHLORINE CELL COMPRISING, DISSOLVING MALEIC ANHYDRIDE IN AN ORGANIC SOLVENT, CONTACTING AN ASBESTOS SHEET WITH SAID SOLVENT CONTAINING MALEIC ANHYDRIDE TO THEREBY IMPREGNATE THE ASBESTOS WITH THE SOLVENT CONTAINING MALEIC ANHYDRIDE, REMOVING THE ASBESTOS SHEET FROM CONTACT WITH SAID SOLUTION AND EVAPORATING THE SOLVENT THEREFROM, CONTACTING THE SUBSTANTIALLY SOLVENT FREE ASBESTOS SHEET WITH A MIXTURE CONSISTING ESSENTIALLY OF DIVINYL BENZENE AND STYRENE, POLYMERIZING THE DIVINYL BENZENE, STRENE AND MALEIC ANHYDRIDE IN THE SUBSTANTIALLY ABSENCE OF THE SOLVENT, SAID MALEIC ANHYDRIDE BEING EMPLOYED IN QUANTITIES OF BETWEEN 0.5 TO 3 MOLES OF MALEIC ANHYDRIDE FOR EACH MOLE OF VINYL UNSATURATION PRESENT IN THE DIVINYL BENZENE-STRENE MIXTURE TO THEREBY PROVIDE A DIAPHRAGM CAPABLE OF PRODUCING AN ALKALI METAL HYDROXIDE CONTAINING LESS THAN 0.1 PERCENT ALKALI METAL CHLORIDE WHEN USED IN THE ELECTROLYTIC PRODUCTION OF CHLORINE AND ALKALI METAL HYDROXIDE BY THE ELECTROLYSIS OF ALKALI METAL CHLORIDE SOLUTION.