Abstract: A method for producing a glass preform for optical fibers by heating a glass soot preform consisting of glass fine particles made mainly of silicon oxide, which method comprises the steps of:(1) heating the glass soot preform to dehydrate and to remove impurities therefrom;(2) heating the glass soot preform in a gas atmosphere containing at least fluorine or fluorine-based compound to add fluorine to the glass soot preform; and(3) heating the glass soot preform to make it transparent, from the transparent preform prepared by which method, an optical fiber having superior transmission characteristics can be prepared.

Abstract: A process for producing a highly expanded polyolefin insulated cable comprising the steps of feeding a compound of polyolefin, nucleating agent and volatile liquid to an extruder, heat extruding said compound through said extruder onto an inner conductor passing through said extruder to cover the outer periphery of said inner conductor thereby forming an insulation layer of highly expanded polyolefin foam having a foaming ratio in excess of 2.5 times (60% expansion degree) tightly adhered to said inner conductor.

Abstract: A process for producing a highly expanded polyolefin insulated cable comprising the steps of feeding a compound of polyolefin, nucleating agent and volatile liquid to an extruder, heat extruding said compound through said extruder onto an inner conductor passing through said extruder to cover the outer periphery of said inner conductor thereby forming an insulation layer of highly expanded polyolefin foam having a foaming ratio in excess of 2.5 times (60% expansion degree) tightly adhered to said inner conductor.

Abstract: A jointer for laminated tapes for use in the production of sheathed cables formed by longitudinally or helically wrapping cable cores with metal tapes laminated with plastic films and by joining the overlapped portions of said tapes by way of heat fusion is disclosed. The method comprises the use of pressing blocks consisting of metal material having a high heat conductivity and respectively having machined surfaces opposing in parallel to each other for the application of uniform pressure to both surfaces of the laminated tapes held therebetween. A heating piece is provided which is electrically insulated from and mounted to the bottom of the pressing block and having relatively high electric resistance and being supplied with electric current thereby pulse heating the portions of the laminated tapes to be spliced.

Abstract: A terpolymer, consisting essentially of (a) a first component of ethylene, (b) a second component selected from an (1) unsaturated glycidyl ester of the following formula (I) and (2) an unsaturated glycidyl ether of the following formula (II), and (c) a third component selected from an alkyl acrylate, an alkyl methacrylate and vinyl acetate, is coated on one or both surfaces of a metal foil to make a laminate tape. ##EQU1## wherein R represents a hydrocarbon residue containing an ethylenically unsaturated bond.The laminate tape is used for preparing a laminate sheathed cable. The terpolymer resin may contain an antioxidant.

Abstract: The mechanical properties of laminate sheathed cables are improved by using as the shielding layer a laminate tape prepared by coating a metallic foil with an ethylene-glycidyl-methacrylate-vinyl acetate terpolymer