Abstract: A high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations. The substrate is made of a vinyl chloride resin, and carbon black which is purified by electrolysis to remove impurities therefrom.

Abstract: An electrostatic capacitance type information signal recording disc comprises a laminated plate made up of a first sheet which is made from an inexpensive conductive or non-conductive material and is used as a core material and a second sheet which is made from a conductive material and is bound on at least one surface of the first sheet, and variations in geometrical configuration formed on the second sheet in accordance with information signals which are to be recorded. A method of manufacturing the disc comprises the steps of binding the second sheet on at least one surface of the first sheet so as to obtain a laminated sheet, cutting the laminated sheet into a plurality of laminated plates having a predetermined size, and compression molding the variations in geometrical configuration, in accordance with information signals which are to be recorded, on a recording part of the second sheet of each of the laminated plates supplied in succession.

Abstract: An information signal recording medium comprises a core material made of a non-conductive material, and a surface material made of a conductive material and in close adherence with at least one surface of the core material. Variations in geometrical configuration in accordance with information signals to be recorded on the recording medium are compression molded on the surface material. The materials constituting the surface material and the core material are selected so that a ratio V.sub.C /V.sub.N between a melt viscosity V.sub.C of the surface material and a melt viscosity V.sub.N of the core material at a temperature and a shear rate at the time of the compression molding is less than or approximately equal to 1.6.

Abstract: A high density information record of the electrostatic capacitance type comprising a record substrate on which signal information is recorded as geometric variations. The record substrate is made of a conductive resin composition comprising a vinyl chloride resin and a conductive powder. The vinyl chloride resin is obtained by suspension polymerization of starting vinyl chloride monomer in an aqueous solution of a water-soluble polymer suspension stabilizer from which insoluble organic matters with sizes over 10 .mu.m have been removed.

Abstract: A high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations. The substrate is made of a conductive resin composition comprising a thermoplastic resin, a conductive material, and a defined amount of a specific type of dimethylpolysiloxane lubricant having a degree of inhomogeneity of 1.0 to 1.3 and a degree of polymerization of 12 to 60.