Thermoplastic mold for rotational molding
OwnerWilliam E. Mastersinventor
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Abstract
A plastic mold (A, B) for rotational molding are disclosed. The plastic mold, used in lieu of a conventional metal mold, is constructed from a fiber (52) reinforced thermoset plastic resin (50) having a heat distortion point above the melt point of the thermoplastic polymeric material from which an article is molded. Metal (64, 70, 74) or other dissimilar material may be used to provide different coefficients of heat transfer at preselected portions of mold (A, B). The entire mold may include a thermal coefficient modifier to increase the heat transfer rate of the mold uniformly over the entire mold in addition to the preselected portions.
Claims9
Rotational molding apparatus for molding an article from a thermoplastic material which includes a rotating mold for containing said thermoplastic material, and drive means for rotating said mold bi-axially to distribute the material in the mold, and an oven for heating the mold to fuse the thermoplastic material together against an inner surface of the mold, wherein said apparatus comprises a thermoset mold constructed of thermoset plastic material having a heat distortion point greater than 423 degrees F. in which said thermoplastic material is molded to form said article;
- and heat conductive modifiers carried by said thermoset mold which act to increase heat transfer which compensates for a normally low rate of heat transfer of said thermoset material.
Dependencies are inferred from the claim text.