Raychem Limited

Other

Mark F Wartenberg

Robert H Reamey

Akira Tomita

John R Havens

Harriette Atkins

James J Toth

Aldrich N Lau

Paul S Drzaic

Laurence M Welsh

Wayne Montoya

Janusz Wojtowicz

James Strain

John G Lahlouh

Philip J Jones

Hundi Panduranga Kamath

Stephen M Jacobs

Pravin L Soni

Peter H Van Konynenburg

Stephen S Moore

Randolph W Chan

Steven C Zingheim

Alan S Yeung

Brackin L Andrews

Anne Gonzales

Gilbert A Garza

Kathleen DiZio

Kevin Malloy

Michael Trowbridge

William Seeley

John Mazzanti

Gil Garza

Mark Bannick

An electrical device in which a resistive element composed of a conductive polymer composition and two electrodes is made by a method in which the device is cut from a laminate of the conductive polymer composition and the electrodes, is exposed to a thermal treatment at a temperature above the melting temperature of the conductive polymer composition, and is then crosslinked.

Method of making an electrical device comprising a conductive polymer

Ignition cables which contain a layer of a melt-extruded conductive polymer. The conductive polymer is preferably the sole current-carrying component of the cable. The polymeric component in the conductive polymer is a fluoropolymer, preferably a vinylidene fluoride copolymer having a crystallinity index of 10 to 23% and/or a DSC heat of melting of 4.7 to 9.5 J/g. Preferably, the sole conductive filler in the conductive polymer is a carbon black.

Ignition cables

A conductive polymer composition which has a resistivity at 20.degree. C. of at most 1.0 ohm-cm and a PTC anomaly of at least 104 contains at most 64% by volume of a crystalline polymeric component and at least 36% by volume of a particulate conductive filler. A preferred conductive filler is carbon black having a DBP number of 60 to 120 cm.sup.3 /100 g. Compositions of the invention, as well as other conductive polymer compositions are preferably prepared by a method in which the polymeric component and the filler are blended in a first step at a temperature greater than the melting temperature of the polymer, the mixture is then cooled, and the mixture is then mixed in a second step. The resulting composition has a PTC anomaly that is at least 1.2 times the PTC anomaly of the first mixture.

Method of making a conductive polymer composition

A conductive polymer composition which has a resistivity at 20.degree. C. of at most 1.0 ohm-cm and a PTC anomaly of at least 10.sup.4 contains at most 64% by volume of a crystalline polymeric component and at least 36% by volume of a particulate conductive filler. A preferred conductive filler is carbon black having a DBP number of 60 to 120 cm.sup.3 /100 g. Compositions of the invention, as well as other conductive polymer compositions are preferably prepared by a method in which the polymeric component and the filler are blended in a first step at a temperature greater than the melting temperature of the polymer, the mixture is then cooled, and the mixture is then mixed in a second step. The resulting composition has a PTC anomaly that is at least 1.2 times the PTC anomaly of the first mixture.

Conductive polymer composition and device

A liquid crystal display is made from an encapsulated liquid crystal structure comprising a liquid crystal composition dispersed in a containment medium. Selected additives may be added to the encapsulated liquid crystal structure to improve performance characteristics such as the operating field, the hysteresis, and the voltage holding ratio.

Encapsulated liquid crystal structures, apparatus containing the same,

A method is described for making a liquid crystal composite in which droplets of a liquid crystal material dispersed in a matrix material. An encapsulating material at least partially separates the liquid crystal material from the matrix material. This construction permits the matrix material to be selected on the basis of its processing and environmental properties and the encapsulating material to be selected on the basis of its emulsifying ability and orientational interactions with liquid crystal material. Light valves made from such a composite exhibit improved electro-optical properties.

Method of making liquid crystal composite

An active matrix liquid crystal display having improved performance properties is made using an encapsulated liquid crystal structure comprising a containment medium having dispersed therein a liquid crystal composition having an average dielectric constant greater than about 6 and other specified characteristics.

Active matrix liquid crystal display with average dielectric constant

Encapsulated liquid crystal material is made by mixing liquid crystals, a containment medium, and a carrier medium made of a water-miscible monohydric alcohol and water in the proportion between 5:95 and 60:40 weight/weight to form an emulsion; applying the emulsion onto a substrate and drying the emulsion to remove the carrier medium.

Method for making encapsulated liquid crystal material

A display having (a) a first electrode; (b) a second electrode; (c) a display medium positioned between the first and second electrodes, which display medium is switchable between a first state in which incident light is at least one of scattered and absorbed and a second state in which the amount of such scattering and/or absorption is reduced; and (d) scattering centers disposed in front of the second electrode for scattering incident light with a scattering half angle of between about 2 and about 40 degrees when the display medium is in its second state, while permitting at least 10% of the incident light to be transmitted.

Display having light scattering centers

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

Growing community of inventors

San Jose, CA, United States of America

Mark F Wartenberg