| 摘要 |
PURPOSE:To absorb intruding water by itself and to prevent running water by using a mixture composed of a hydrophobic material used as a base and a water absorptive material as a packing material for preventing the running water. CONSTITUTION:Eight pieces of optical fiber core units 1 each formed by gathering six pieces of optical fibers around a tensile member 11 such as a metallic wire and winding a tape 13 for retentive winding are gathered around a tensile member 2 and are covered with a water shielding layer 3 consisting of Al, etc. and an extruded protective sheath layer 4. A packing material 5 is packed in the inside space of the layer 3 and a mixture composed of a hydrophobic material and a water absorptive material is used as a packing material 5. Various hydrophobic materials such as polyurea grease, lithium soap grease, etc. are enumerated as the hydrophobic materials. The water absorptive material acts to prevent running water by absorbing the water by itself when the water intrudes to the inside of the layer 3. There are org. water absorptive materials such as polymer-grafted starch like acrylic acid modified starch, polymer-grafted cellulose, carboxymethyl cellulose, acrylic acid polymer, etc. and inorg. materials such as silica gel and quicklime as the water absorptive material. |
