Optical fibre cable utilizing thermotropic liquid crystal polymer and method of making same
AssigneeImperial Chemical Industries PLC
InventorTimothy G. Ryan
Life of this patent
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Abstract
Optical fibre cables are produced containing an extruded support member of thermotropic liquid crystalline polymer in which the extrusion conditions are used to control the thermal expansion coefficient of the support member. The support member may be extruded on to the support member. In this case extrusion conditions may be used to induce a compressive strain on the fibre which can counteract the thermal change in length of the fibre when subject to temperature variations so that a cable having temperature variation can be produced. Support members which provide a loose fitting sleeve over the fibre can be produced by control of extrusion conditions to have a thermal expansion coefficient of not less than -5.times.10.sup.-6 /.degree.K.
Claims13
An optical fibre cable in which a thermotropic liquid crystalline polymer is used to provide a support member in the cable characterized in that said polymer is present as a coating surrounding and contacting the optical fibre, that the linear thermal expansion coefficient of the coating is negative and is less than that of the optical fibre, and wherein a strain of less than 0.2% is introduced into the optical fibre when the cable is subjected to temperatures over the range of -50.degree. C. to +150.degree. C.
A process of forming an optical fibre cable reinforced with a support member comprising melt extruding an elongated tube of thermotropic, liquid crystalline polymer through a die around an optical fibre under conditions such that the tube surrounds and contacts the optical fibre and the linear thermal expansion coefficient of the tube is negative and is less than that of the optical fiber and such that a strain of less than 0.2% is introduced into the optical fibre when the cable is subjected to temperatures over the range -50.degree. C. to +150.degree. C.
Dependencies are inferred from the claim text.