Westinghouse Electric Corporation

Siemens Westinghouse Power Corporation

Wei-Fang A Su

Karl F Schoch, Jr

Luciano C Scala

Anthony P Barrett

James D Smith

William H Kasner

Dean C Westervelt

Vincent A Toth

Roger L Swensrud

Daniel P Soroka

Frank A Sattler

Steve A Wutzke

This invention relates to novel ecologically compatible water-based stable mullite precursor sols, mullite composites, and methods for making the same. The mullite precursor sols are synthesized using tetraethoxysilane and aluminum nitrate in water. The tetraethoxysilane is hydrolyzed with water and ammonium hydroxide catalyst to make a silica sol, which is then quenched with an aqueous solution of aluminum nitrate. The mullite precursor sols of the invention may be used to make highly densified ceramic composites.

Methods for making ecologically compatible water-based mullite sols and

Liquid crystal thermoset epoxy resin is used as an electrical insulator on electrical conducting devices such as coils and transformers. The linear epoxy/mesogen/epoxy molecule of the liquid crystal thermoset epoxy resin results in a electrical insulator with a high degree of crystallinity. This results in an electrical insulator with mechanical and electrical properties suitable for use in high temperature, high stress environments.

Electrical insulation using liquid crystal thermoset epoxy resins

Resin compositions comprising 20 to 50% by weight, based on total composition weight, of a first resin which comprises an acrylate-epoxy oligomer having a molecular weight of from 2000 to 5000; from 2 to 10% of a second resin which comprises an acrylate-urethane oligomer; up to 50% of a third resin which comprises a second acrylate-epoxy oligomer, where from 1 to 5% of the epoxy is an epoxy novolac; from 10 to 40% of a liquid acrylate; from 2 to 20% of a liquid diacrylate having an ether linkage; from 5 to 25% of a liquid alkylene diacrylate; and from 1 to 5% of a UV photoinitiator. The compositions also preferably includes from 0.05 to 1% of a flow control agent. The compositions are applied to substrates such as printed wiring boards and cured with ultraviolet light to form a conformal coating on the substrate.

UV conformal coatings

Solventless ultraviolet (UV) radiation curable polyamideimides which are useful as coatings for substrates are disclosed. The UV curable solventless polyamideimides are prepared by grafting acrylate functionality on the polyamideimide backbone The polyamideimides of the invention may be a part of UV curable compositions.

Ultraviolet radiation curable polyamideimide oligomers

A two package UV curable conformal coating has been developed which possesses low moisture permeability and good electrical properties and provides a cure for shadowing of components on a printed wiring board. The conformal coating is a mixture of Component (A) which is a mixture of (1) from about 40 to 80% by weight, of a urethane having a free isocyanate group; (2) from about 20 to 60%, by weight, of reactive acrylate diluents; (3) from 0 to about 10% by weight of UV photoinitiators; and (4) from 0 to about 10% by weight of additives; and component (B) which is a mixture of (1) about 50 to 80% by weight of an acrylate-epoxy resin; (2) about 1 to 10% by weight of an acrylate-urethane oligomer; (3) about 10 to 94% by weight of reactive acrylate monomers; (4) from 0 to about 10%, by weight, of UV photoinitiators; and (5) from 0 to about 10% by weight of additives; with the proviso that the total weight percentage of said photoinitiators and additives not be less than 1 percent and not exceed about 10 percent. Components A and B may be mixed in equal parts, by weight, or in a 1 to 2 part ratio, by weight.

Ultraviolet curable conformal coatings

A UV curable electrically conductive adhesive has been developed with low resistivity, adequate lap shear strength, good thermal stability, and very stable conductivity at high temperatures of about 100.degree. C. and high humidity. The adhesive may be applied by silk screen printing and cured by UV in about 8 seconds. The adhesive may also be used as a replacement of solder in automated surface mount technology for electronic circuit fabrication. The adhesive is a mixture of (A) a blend of an acrylate epoxy and a urethane, a copolymer of an acrylate epoxy and a urethane, or mixtures thereof; (B) a polyfunctional acrylate monomer; (C) a photoinitiator, and (D) a conductive filler. Optionally, adhesion promoters and flow control agents may be used.

Ultraviolet curable conductive resin

A system which utilizes a source of ultraviolet radiation to mark a surface or to cure selectively a photosensitive paint applied to a surface. The source of UV light is either a laser or a broadband source and the light is controlled by an aperture and/or a stencil apparatus. The photosensitive paint is applied by a controlled technique as a protective or a decorative coating.

Technique for the application and cure of photosensitive paints

A void-free prepreg is made by contacting a porous sheet material with a resin so that resin enters the sheet, providing a subatmospheric pressure on one side of the resin-containing sheet to draw resin through the sheet, and then B-staging the resin-containing sheet.

Method of continuously vacuum impregnating fibrous sheet material

Disclosed is a resin composition which comprises a mixture of a polyester, an acrylate urethane, in about stoichiometric proportion with the polyester up to about 10% excess polyester over stoichiometric, and a liquid acrylate reactive diluent sufficient to give the resin composition the viscosity of less than 5,000 centipoise. The polyester resin is the reaction product of a polyhydroxy compound having at least three hydroxyl groups, and an aromatic compound that is at least difunctional in acid, anhydride, or ester groups, where the proportion of the polyhydroxy compound to the aromatic compound is such that the polyester has about 150 to about 250 mole % excess hydroxyl groups. The acrylate urethane compound is the reaction product of a hydroxy acrylate and an isocyanate having at least two isocyanate groups, where the hydroxy acrylate and a hydroxy acrylate having a single hydroxyl group are equimolar (when a diisocyanate is used) with the isocyanate .+-.10 mole %. Also disclosed is a method of making the resin composition.

UV curable high tensile strength resin composition

A tape useful for bonding electrical coils can be made flexible upon cure by using an impregnating varnish composition comprising a blend of (A) an alkyd component reaction mixture containing at least 29 equivalent % of fatty acid, and (B) an alkyl acrylate monomer.

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Murrysville, PA, United States of America

Wei-Fang A Su