Hydrophilic copolymer and process for its manufacture

L'INVENTION A TRAIT A UN COPOLYMERE HYDROPHILE ET A SON PROCEDE DE PREPARATION.ON PREPARE LE COPOLYMERE PAR COPOLYMERISATION D'UN MELANGE DE MONOMERES DE 2-HYDROXYETHYL METHACRYLATE ET DE 2-(2-HYDROXYETHOXY)ETHYL METHACRYLATE, A RAISON DE 90 A 99,99 EN POIDS, AVEC L'ACIDE METHACRYLIQUE OU L'ACIDE ACRYLIQUE LIBRES OU AVEC LEURS SELS DE SODIUM, POTASSIUM OU AMMONIUM, A RAISON DE 10 A 0,01 EN POIDS, EN PRESENCE D'INITIATEURS DE RADICAUX, LA TENEUR EN 2-(2-HYDROXYETHOXY)ETHYL METHACRYLATE DU MELANGE DE MONOMERES DE 2-HYDROXYETHYL METHACRYLATE ET DE 2-(2-HYDROXYETHOXY)ETHYL METHACRYLATE ETANT DE 0 A 50 EN POIDS ET LE TOTAL DE MELANGE DE MONOMERES CONTENANT 0,01 A 4 EN POIDS D'UN AGENT DE RETICULATION COMPORTANT AU MOINS DEUX DOUBLES LIAISONS OLEFINIQUES.LE COPOLYMERE HYDROPHILE CONVIENT SURTOUT POUR LES LENTILLES DE CONTACT ET POUR APPLICATIONS MEDICALES. A hydrophilic copolymer can be prepared by the copolymerization of a monomer mixture of 2-hydroxyethyl methacrylate and 2-(2-hydroxyethoxy)ethyl methacrylate, in an amount ranging from 90 to 99.99 wt.%, with free methacrylic acid or acrylic acid or with at least one of their sodium, potassium or ammonium salts in an amount ranging from 10 to 0.01 wt.% in the presence of radical initiators. The content of 2-(2-hydroxyethoxy)ethyl methacrylate in the monomer mixture of 2-hydroxyethyl methacrylate and 2-(2-hydroxyethoxy)ethyl methacrylate ranges from 0 to 50 wt.% and the entire monomer mixture contains from 0.01 to 4 wt.% of a crosslinking agent having at least two olefinic double bonds. The hydrophilic copolymer is suitable for contact lenses and medical applications.