Mantelmaterial für optische Fasern.

摘要

A cladding material for an optical fiber is described, which is made of a polymer comprised of (A) 10 - 90 wt.% of a long-chain fluoroalkyl group-containing monomer of the formula: CH2= @-COO(CH2)2(CF2)nCF3 wherein F is F, CH3 or CF3, and n is an integer from 5 to 11, (B) 5 - 90 wt.% of a short-chain fluororalkyl group-containing monomer of the formula: CH2= @-COOCH2(CF2)mX wherein Y is as defined above, X is F, CH3 or CF3, and m is an integer of from 1 to 4, and (C) 0 - 50 wt.% of other copolymerisable monomer. The melt flow index indicating the amount in gram of the polymer extruded for 10 minutes from a nozzle with an orifice having an inner diameter of 2mm and a length of 8mm under the conditions of a temperature of 230 DEG C and a load of 5kg, is not larger than 30. The material can be used as cladding in a core-clad optical fiber in which the light transmittance retention ratio Ia/Io when wound satisfies the requirement represented by the following formula: Ia/Io x 100 >/= 20% wherein Io stands for the intensity of transmitted light measured when parallel light having a specific wavelength is made incident from one end of the optical fiber having a length of 10m and emitted from the other end thereof, and Ia stands for the intensity of transmitted light obtained when the optical fiber is wound by 100 turns on a rod-shaped mandrel having a diameter of 10mm and the measurement is conducted in the same manner as described above.