Holl Technologies Company

Kreido Laboratories

Kenneth S Yao

Richard A Holl

Philip L Lichtenberger

Composite materials, particularly those that are highly filled, e.g. comprising about 60 to 70 volume % of finely powdered filler material in a polymer matrix, are made by dissolving the polymer in a volatilisable solvent and forming a homogeneous mixture of the components by high shear mixing. The solvent is then removed while maintaining complete homogeneity in the mixture by evaporating much of the solvent in a high shear mill, then extruding an extremely thin film or tape (e.g. 0.0125 mm (0.0005 in)) from which the remaining solvent is removed by heating without introducing any appreciable non-uniformity, such as bubble holes. Required bodies are formed from the dried film or tape by stacking the thin coherent layers, typically about 6 to 120, then heating and pressing the stack in a mold melting the polymer, uniting the separate layers and dispersing the melted polymer into the interstices between the filler particles.

Manufacture of flat surfaced composites comprising powdered fillers in a polymer matrix

Highly filled composite materials, e.g. comprising approximately 60 volume % or greater of finely powdered particles of filler in a polymer matrix, are made by dissolving polymer in a volatilisable solvent, adding filler and forming a homogeneous mixture by high shear mixing. Most solvent is then removed while maintaining homogeneity in the mixture, preferably by evaporation in a high shear mill. Then, extruding a thin layer of the composite material and removing remaining solvent, as by heating. Bodies are formed from the dried layer, which are heated and pressed to melt and disperse melted polymer into the interstices between filler particles. Thereby, certain polymers unusable at low solids contents become effective bonding materials at high solids contents. Filler materials are chosen to tailor electrical and physical properties of the articles, which may comprise substrates for electronic circuits. Suitable polymers are certain polyarylene ethers soluble in cyclohexanone.

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San Gabriel, CA, United States of America

Kenneth S Yao