| 摘要 |
PURPOSE:To prevent exertion of the compressive stress of the coating layer itself on an article by forming a protective coating of >=2 layers consisting of an inside layer and outside layer having the Young's modulus higher than the Young's modulus of the inside layer and providing a stress relieving layer between the article and the inside layer. CONSTITUTION:The protective coating layer of a glass fiber 1 consists of the inside layer 2, the outside layer 3 having the Young's modulus higher than the Young's modulus of the inside layer and high strength, and the stress relieving layer 4 provided between the optical fiber 1 and the inside layer 2. The material to be used as the soft inside layer is exemplified by thermosetting silicone rubber, thermoplastic rubber, etc., and the material to be used as the hard outside layer having the Young's modulus higher than the Young's modulus of the inside layer is exemplified by the resins similar to the resins for the inside layer, material which is increased in the Young's modulus in compsn., thermoplastic resins, etc. The stress relieving layer is provided between the article to be protected by the coating and the inside layer and may be provided with a gap. The direct transmission of the working strain of the cladding and the compressive stress to the object (fiber) is thereby obviated.
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