Conductive molding composition
AssigneeRCA Corporation
InventorsCarl J. Martin, Marvin J. Voelker, Robert J. Ryan
Life of this patent
Estimating the term…
Abstract
An improved molding composition having a bulk resistivity below about 500 ohm-cm at 900 megahertz for compression molding video discs comprising sufficient conductive carbon black particles to obtain the desired conductivity, from about 1.5 to 4 percent by weight of stabilizers, from about 1 to 3 percent by weight of at least two lubricants, up to 10 percent by weight of plasticizers and processing aids, the remainder being a polyvinylchloride based resin, with the proviso that not more than about 5 percent by weight of liquid additives are present in said molding composition. Video discs molded from said composition have improved dimensional stability.
Claims9
A conductive molding composition comprising
- sufficient finely divided conductive carbon black particles so that the composition has a bulk resistivity below 500 ohm-cm at 900 megahertz,
- from about 1.5 to 4 percent by weight of stabilizers for polyvinylchloride resins:
- from about 1 to 3 percent by weight of at least two lubricants for polyvinylchloride resins;
- up to 10 percent by weight of plasticizers and processing aids for polyvinylchloride resins, and the remainder a polyvinylchloride-based resin, having a T.sub.g of at least 60.degree. C., with the proviso that not more than about 5 percent by weight of liquid additives that are compatible with the polyvinylchloride resin are present and wherein the carbon black, stabilizers, lubricants, plasticizer and processing aids are uniformly dispersed with the resin.
In a information record, adapted for use with a playback stylus to effect recovery of signals occupying a bandwidth of at least several megahertz when relative motion at a desired rate is established between said record and said stylus, said record comprising a disc of a plastic material containing finely divided conductive particles and having a bulk resistivity below about 500 ohm-cm at 900 megahertz, said record havig an information track in a surface, said information track constituted by a surface relief pattern of such dimension to accommodate recovery of signals of said bandwidth upon establishment of said motion at said rate, the improvement comprising employing as said molding composition a conductive molding composition comprising conductive carbon black particles;
- from about 1.5 to 4 percent by weight of stabilizers for polyvinylchloride resins;
- from about 1 to 3 percent by weight of at least two lubricants for polyvinylchloride resins;
- up to 10 percent by weight of plasticizers and processing aids for polyvinylchloride resins and the remainder a polyvinylchloride-based resin having a T.sub.g of at least 60.degree. C., with the proviso that not more than about 5 percent by weight of liquid additives that are compatible with the resin are present and wherein the carbon black, stabilizers, lubricants, plasticizer and processing aids are uniformly dispersed with the resin.
Dependencies are inferred from the claim text.