Importance

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Abstract

Improved optical disks for information storage and holographic imaging, and optical lenses and reflective optical elements are among the difficult-to-mold thermoplastic products which require precision replication of the molding surfaces, in micro detail. By heating (with circulating heat transfer fluids supplied by a hot side reservoir) these mold surfaces to a temperature setpoint sufficiently high to retard solidification and premature viscoelastic skinning of the molten thermoplastic injected into the mold cavity, superior quality molded surfaces can be formed by the plastic, which is then rapidly cooled to solidification (by circulating heat transfer fluids supplied from a cold side reservoir). Each injection molding cycle thus starts with a heating phase, wherein molding surface temperature increase is thermally driven by hot side reservoir fluid temperatures above the melt-solidifying temperatures (Tg or Tm) characteristic to the thermoplastic, followed by a cooling phase, wherein molding surface temperature decrease is thermally driven by cold side reservoir fluid temperatures below the melt-solidifying temperatures (Tg or Tm) characteristic to the thermoplastic. The greater these temperature differences are, the faster the molding cycle will be. Fluid control units and electronic process sequence control units are interconnected to govern the flow of these fluids into and out of the injection mold and the reservoirs in accordance with the predetermined logic of the process flowsheet.

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First Claim