PRODUCTION OF GLASS FOR OPTICAL FIBER

摘要

PURPOSE:To produce glass for optical fiber free from foaming in a period of wire drawing by aging a sol soln. sufficiently which is obtained by hydrolyzing an alkoxide soln. contg. ammonia and thereafter gelatinizing and drying it and furthermore vitrifying it transparently at high temp. CONSTITUTION:A uniform sol soln. 1 is prepared by adding water contg. NH3 to the soln. wherein alkoxide such as Si(OC2H5)4 is diluted by alcohol and hydrolyzing the mixture. Then the above-mentioned sol soln. 1 is aged while interrupting the outside air and furthermore water or aq. ammonia is added thereto in at least one time and the mixture is aged and thereafter gelatinized. A dried porous gel material 3 is formed by heating this gel 2 slowly to dry it and volatilizing alcohol and water content or the like. Then a sample 4 of the dried gel material is introduced into a vessel 8 and preferably while flowing Cl2 or halogenocompd. through a gas introduction port 5 and a discharge port 6, the sample is slowly raisen in temp. at about 1,200-1,400 deg.C in an electric furnace 7 and subjected to high-temp. treatment and transparently vitrified. Thereby a glass sample 9 which is optically uniform and has high purity is obtained.