Abstract: A coated optical fiber comprising an optical fiber; a first layer of a thermoplastic rubber composition which is disposed around the circumference of the optical fiber, has a Young's modulus of 0.1 GPa or less, and is capable of extrusion coating; and a second layer of a thermoplastic resin composition which is disposed around the circumference of the first layer, has a linear expansion coefficient of 1.times.10.sup.-5.degree. C..sup.-1 or less and a Young's modulus of 5 GPa or more, and is capable of extrusion coating. The coated optical fiber has excellent transmission characteristics at low and high temperatures and is inexpensive.

Abstract: A UV-ray curable resin composition comprising a polyurethane derived from a polyether polyol and a diene polymer having hydroxyl group, said polyurethane having polymerizable double bond different from the carbon-carbon double bonds contained in said diene polymer having hydroxyl group, and a coated optical fiber having a coated layer comprising the cured product of said resin composition. This composition has good coating characteristics, and the cured product thereof has small modulus over a wide temperature range and good hydrolysis resistance, and water absorption resistance. The coated optical fiber has small transmission loss over a wide temperature range and has high strength even in water.

Abstract: A protective packaging method of protecting the spliced portion of optical fibers, comprising the steps of providing a protective packaging assembly having a heat-shrinkable tube capable of shrinking in the radial direction thereof, an extended form of hot-melt adhesive disposed on the inner side of the heat-shrinkable tube, and an electrical resistance heating element so disposed on the inner side of the heat-shrinkable tube and extendedly in the axial direction of the heat-shrinkable tube as to be capable of heating both the heat-shrinkable tube and the extended form of hot-melt adhesive, and a space provided in the heat-shrinkable tube for allowing the passage of the optical fiber; placing the protective packaging assembly around the splice portion of the optical fiber which has been passed through the space; and supplying electric current through the electrical resistance heating element to heat-melt the hot-melt adhesive and to heat-shrink the heat-shrinkable tube for forming a reinforced unit including

Abstract: This invention discloses a continuous process for the production of polymer-polyoxymethylene (POM) having small linear expansion coefficients and high tensile modulus, the process for producing an ultrahigh modulus POM comprising the step of drawing a crystalline polymer continuously under dielectric heating while maintaining the ambient temperature at an elevated temperature by external heating, said ambient temperature being controlled to change from a lower temperature to a higher temperature along the drawing direction of said crystalline polymer with a pre-set temperature gradient.