Raychem Limited

Randolph W Chan

Paul B Germeraad

Robert S Dubrow

James T Triplett

Stephen M Jacobs

Pravin L Soni

Dennis C Siden

Michael L Jensen

Mark F Wartenberg

Peter H Van Konynenburg

Albert R Martin

Richard E Rodkey

Lawrence D Schwartz

Christine J Holland

Ted M Aune

Permanent white indicia are applied to a polymeric surface, preferably of a black, heat-recoverable marker sleeve for wire or cable, using an ink composition comprising a pigment that is thermally stable at a temperature of at least about 350.degree. C., preferably titanium dioxide and a binder, such as nitrocellulose, and then heating the surface to permatize the mark. The marked article passes MIL-STD-202 in mark permanence.

Article having permanent indicia thereon

This invention provides E.M.I. gaskets for electrically shielding and environmentally sealing the space between two surfaces which comprises a metallic electrically conductive deformable structure adapted for forming electrical contact with said surfaces and/or providing electrical shielding in the space between said surfaces; and a gel material for sealing the space between said surfaces having a cone penetration value of about 100 to about 350 (10.sup.-1 mm) and an ultimate elongation of at least 200% and being present in sufficient amount and positioned to provide environmental seal between said surfaces and to provide environmental protection for said metallic structure. The gel may encapsulate the entire metallic structure so that portions of the metallic structure pierces through the gel when the gasket is installed to make electrical contact. Alternatively portions of the metallic structure may extend beyond the surface of the gel and the gel deforms to cover exposed portions of the metallic structure when the gasket is installed. The gasket of this invention provides moisture seal and is resistant to corrosion.

Shielding and sealing gaskets

An electrical heater which includes a fabric prepared from electrodes and an elongate resistive heating element which is composed of a conductive polymer, preferably a PTC conductive polymer, to render the heater self-regulating. The fabric is laminated to, and preferably embedded in, a sheet of an insulating polymer, particularly a non-tracking insulating polymer.

Electrical devices comprising fabrics

The resistivity/temperature characteristics of PTC conductive polymers which have little or no cross-linking can be modified by stretching. The rate at which resistivity rises with temperature is increased, and the peak resistivity is decreased; however, the decrease in peak resistivity is substantially smaller than that observed with PTC conductive polymers having a high degree of cross-linking. Therefore, heat-recoverable electrical devices, particularly for covering telephone and other cable splices, comprise (a) a layer of a PTC conductive polymer which has little or no cross-linking, (2) an adjacent heat-recoverable layer of a PTC or ZTC conductive polymer which has a relatively high level of cross-linking, and (3) electrodes which can be connected to a power supply so that current passes through the layers and causes recovery of the device; preferably an uncrosslinked PTC layer is sandwiched between two cross-linked ZTC layers. Non-recoverable devices, e.g. heaters, can have valuable characteristics when they comprise PTC conductive polymer elements which have been given a relatively low degree of orientation by stretching.

Devices comprising PTC conductive polymers

An electrical heater which comprises a fabric prepared from at least one of the electrodes and another elongate element of substantially higher resistance. The heater preferably comprises a PTC element, e.g. of a conductive polymer, to render the heater self-regulating. The PTC element may be in the form of a fiber forming part of the fabric, or a layer surrounding one of the electrodes, or a laminar element in which the fabric is embedded. The fabric can if desired be laminated to a sheet of a polymer, e.g. an insulating polymer or a ZTC conductive polymer. A shrinkable fabric heater can be made by incorporating a heat-shrinkable non-conductive filament into the fabric, perpendicular to both electrodes, and is useful for example for enclosing splices in telephone cables.

Growing community of inventors

Palo Alto, CA, United States of America

Randolph W Chan