Optical glass fibre having a synthetic resin cladding and method of manufacturing same

Claim 1

An optical fibre having a synthetic resin cladding, comprising a glass fibre and an enveloping layer of a synthetic rubber having a refractive index which is higher than the refractive index of the outermost layer of the glass fibre, the synthetic rubber being formed from a curable synthetic resin composition which comprises a copolymer which has monomeric units comprising dimethyl siloxane and at least one siloxane selected from the group consisting of methyl phenyl siloxane and diphenyl siloxane, characterized in that the copolymer is a compound of the formula ##STR3## where R 1 and R 8 are organic groups which are selected from the group consisting of alkyl groups, aryl groups and acrylate-containing alkyl groups, wherein R 2 , R 3 , R 4 , R 6 and R 7 are organic groups which are selected from the group consisting of alkyl groups and aryl groups, and wherein R 5 is an acrylate-containing organic group, the average molecular weight of the polymer molecules being between 1,000 and 1,000,000, the average fractions of the monomeric units per polymer molecule being within the following limits: ______________________________________ 0.005 ≦ p ≦ 0.995 0≦ q ≦ 0.995 0≦ r ≦ 0.49 0≦ s ≦ 0.1 ______________________________________ wherein 0.005≦(q+2r)≦0.995 and wherein the monomeric units may be distributed in the molecule blockwise, alternatingly or randomly and in which the copolymer comprises at least two acrylate groups per molecule.