Insulated mold structure for injection molding of optical disks
AssigneeGeneral Electric Company
InventorsBang M. Kim, Matthew F. Niemeyer
Life of this patent
Estimating the term…
Abstract
An insulated mold insert is provided for injection molding compact disks and optical disks. The mold insert is removably located in the mold cavity behind the stamper. The mold insert has an insulation layer retaining heat at the molding surface, thereby increasing surface smoothness of the molded part. The insert may have a metal surface for contacting the back side of the stamper.
Claims31
A molding apparatus having a stamper for molding molten thermoplastic materials into finished optical media comprising:
- a support for receiving the stamper;
- and
- an insulating mold insert removably located between the support and the stamper for slowing initial cooling of the thermoplastic during molding, said insert having an insulating layer with a thickness dimension, the thickness dimension having a center region and two edge regions, and a density variation across the thickness dimension wherein the center region of the thickness dimension has a low density and the edge regions have a high density.
A method for molding an optical medium comprising the steps of:
- charging a molten thermoplastic material into a molding apparatus having a stamper and a support for receiving the stamper;
- and an insulating mold insert removably located between the support and the stamper for slowing initial cooling of the thermoplastic during molding, said insert having an insulating layer with a thickness dimension, the thickness dimension having a center region and two edge regions, and a density variation across the thickness dimension wherein the center region of the thickness dimension has a low density and the edge regions have a high density;
- retaining the material in the mold for a time sufficient for the material to cool below its glass transition temperature to form the optical medium;
- and
- ejecting the optical medium from the mold.
A mold insert for a molding apparatus having a stamper for molding molten thermoplastic materials into finished optical media, and a support for receiving the stamper comprising an insulating layer insert removably located between the support and the stamper for slowing initial cooling of the thermoplastic during molding, said insulating layer insert having a thickness dimension, the thickness dimension having a center region and two edge regions, and a density variation across the thickness dimension wherein the center region of the thickness dimension has a low density and the edge regions have a high density.
Dependencies are inferred from the claim text.