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Filled resin lamp reflector with no base coat and method of making

  • US 5,916,496 A
  • Filed: 08/11/1998
  • Issued: 06/29/1999
  • Est. Priority Date: 02/15/1996
  • Status: Expired due to Term
First Claim
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1. A method of injection molding a filled resin providing a surface reflector region on a molded part with quality high enough to be metallized to a reflective surface without requiring a base coat, comprising the steps of:

  • a) providing a mold having an internal wall defining a cavity, at least a portion of the internal wall, adjacent the part region to receive a reflector quality metallization, being polished to a degree equal to or greater than the surface quality sought in the molded part;

    b) starting with a bulk molding, thermoset material including glass fibers and mineral fillers comprising in combination at least ten percent by weight of the pre-cured molding material;

    c) injection molding the bulk molding material into the mold with an injection mold machine having a barrel and screw feed while;

    d) maintaining the barrel temperature high enough to maintain the bulk molding material in a sufficiently viscous state to enable a high injection flow rate;

    e) maintaining a back pressure on the injected bulk molding material;

    f) maintaining an injection flow rate as high as possible, with out causing dieseling of the bulk molding material;

    g) maintaining an injection pressure sufficient to induce the flow rate,h) providing a cushion of injection material between the molded part, and the screw end to enable a hold pressure;

    i) maintaining the hold pressure at sufficient pressure and time duration to assure complete contact between the bulk molding material and the internal wall of the mold, at least in the reflector region of the part;

    j) maintaining the mold surface temperature greater than the melting temperature of the bulk molding material, but less than any temperature at which deterioration of the bulk molding material occurs;

    k) maintaining the mold surface temperature to within a sufficiently narrow temperature variation across the mold, at least in the reflector region of the part, to maintain even material characteristics; and

    l) maintaining the bulk molding material in the mold for a time sufficient to thermoset the resin, and thereby rigidify the part sufficiently for safe removal of the part, wherein the reflector region has a surface with a lower percent fill material than the remainder of the part.

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