Raychem Limited

Pradeep Barma

Chi-Ming Chan

Corey J McMills

Nachum Rosenzweig

Manoochehr Mohebban

Julian Sean Mullaney

David D Liu

David J Chazan

Barry C Mathews

John A Ross

Robert J Ritter

Eugen L Kurjatko

John R Hughes

Jeffrey A Sampson

Johann D'Hondt

Hans Cordia

Articles including a thin laminar heating element composed of a sintered conductive polymer, and electrodes attached to the heating element so that current flows in the plane of the element. The article can be placed between and in contact with two substrates, and then heated to join the two substrates together. Preferably at least one of the substrates is polymeric and becomes melt-fused to the article.

Methods and devices which make use of conductive polymers to join

A flexible heater in which a heating element in the form of a tape is wrapped around a support member in the form of a flat sheet. The tape, which exhibits flexibility and toughness, has a composition composed of conductive sintered ultrahigh molecular weight polyethylene. The flexible heater is suitable for heating an upholstered seat, e.g. an automobile seat.

Seat heater

Conductive polymer composition

A composition which comprises a matrix polymer and, distributed therein, a particulate conductive filler. At least some of the filler particles are composed of a conductive polymer composition and/or the matrix comprises a sintered polymer. The matrix polymer and the filler particles and the method of distributing the particles are such that the particles maintain their identity in the matrix. For example, the particles are preferably highly cross-linked so that they have a hot modulus of at least 250 psi if the composition is prepared by melt extrusion or another process involving a high degree of shear; or a low-shear process such as sintering can be used. Preferably the matrix polymer is capable of coating the filler particles; for example, the matrix polymer and the filler polymer may be chemically similar. The invention is particularly useful for preparing compositions which have high resistivities, eg. 1000 ohm.cm or more, and which can be prepared with a high degree of reproduceability. The compositions can exhibit PTC, ZTC or NTC behavior, depending on the nature of the conductive filler, and their resistivity is dependent on the electric field. The compositions are particularly useful as resistive materials in sheet heaters and as stress-grading materials for high voltage apparatus.

A dish antenna for receiving or transmitting signals, e.g. via a satellite, is heated by means of radiant heat from an electrical heater located behind the antenna and spaced apart therefrom. This keeps the antenna free from ice and snow and minimizes distortion. The heater is preferably a self-regulating sheet heater comprising a PTC conductive polymer.

Heated dish antennas

Improvements to electrical devices comprising conductive polymer compositions are described. The device, preferably a heater, comprises two electrodes, preferably planar electrodes and a conductive polymer composition, which preferably exhibits PTC behavior, and which is preferably sandwiched between the electrodes. At least one of the electrodes comprises a metal with a thin layer of high resistivity material attached thereto, e.g. anodized aluminum, so that the layer separates the electrode and the conductive polymer composition. This raises the room temperature resistance of the device and thus reduces the in-rush current.

Electrical devices

Growing community of inventors

Fremont, CA, United States of America

Pradeep Barma