JPH0125148B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-density information signal recording medium such as a video disk or a digital audio disk, and in particular, information signals are recorded as changes in the geometric shape of the surface, and a playback needle relatively scans the surface. A capacitive type high-density information signal recording medium in which an information signal is reproduced by changing the capacitance between the electrode and the electrode according to a change in geometrical shape, and this high-density information signal recording medium By constructing the disc from a material containing thermoplastic resin, conductive carbon black, and approximately 0.2 to 2.5% by weight of fatty acid ester having hydroxyl groups, the disc surface is less likely to wear out even when the regeneration needle scans the disc surface during regeneration. Therefore, even when used for a long time, the shape of the pit is unlikely to change and accurate regeneration can be achieved.Also, when molding discs from the above materials, the viscosity during kneading is low, making kneading easy, and furthermore, the press time is shortened. It is an object of the present invention to provide a high-density information signal recording medium which has a short length, a long dynamic thermal stability of the material, no fear that the material will decompose during kneading, and excellent workability. . Conventionally, pits are formed in a plane or groove according to an information signal, the information signal is recorded as a change in geometrical shape to obtain an information signal recording medium, and electrodes are placed on the recording track of this information signal recording medium. Recorded information is recorded by scanning the provided reproducing needle relatively and utilizing the fact that the capacitance formed between the electrode of the reproducing needle and the information signal recording medium changes in accordance with the change in the geometrical shape. There is a so-called capacitive regeneration method for regenerating signals. A capacitive information signal recording medium used in this type of capacitance reproduction method has, for example, a press-molded recording medium body with a geometric shape change, and static electricity between the surface and the electrode of the reproduction needle. For example, a thin metal film with a thickness of several hundred angstroms is deposited as an electrode to form capacitance, and on top of that, a thin metal film of several hundred angstroms is deposited to protect the metal thin film, prevent short circuits between the electrodes, and increase the dielectric constant between the electrodes. A recording medium with a structure in which a dielectric thin film of 100 Å is attached has been proposed, but recording media with this type of structure require many manufacturing processes, such as press molding of the recording medium body, metal thin film attachment, dielectric thin film attachment, etc. requires
It has drawbacks such as being complicated and troublesome to manufacture, requiring large-scale manufacturing equipment, and extremely high manufacturing cost. Therefore, we press-molded a conductive plastic made by mixing several tens of parts by weight of a conductive material, such as carbon black, with a resin such as vinyl chloride, and record information signals as changes in geometric shape. A capacitive information signal recording medium has been proposed, in which capacitance is formed between the recording medium itself and the reproducing needle electrode, so there is no need for a metal thin film adhesion process, and carbon Since the black fine powder particles themselves are coated with resin, there is no need to apply a dielectric thin film, and the product is said to have the advantage of being extremely simple and low-cost to manufacture. However, even in a recording medium made by forming predetermined pits with a resin containing carbon black as described above, if it is attached to a playback device and the playback operation is performed for a long time, the pits may come into contact with the surface of the recording medium. The reproducing needle abrades the surface of the recording medium and deforms the shape of the pit, which changes the capacitance, making it impossible to obtain accurate reproduction, and the processability of the recording medium is also not very good. be. The present invention eliminates the above drawbacks, that is, as a constituent material of a high-density information signal recording medium,
In addition to vinyl chloride resin, carbon black, and surface lubricants, the S/N ratio can only be improved by using a fatty acid ester having a hydroxyl group, such as glycerin ester, which retains at least one hydroxyl group. Rather, they found that it has particularly excellent still properties, has a low viscosity during heating and melt-kneading, has a long dynamic thermal stability, and has significantly improved processability. In addition, from the viewpoint of still characteristics, etc., it is preferable that the amount of the fatty acid ester having a hydroxyl group, which is an essential component, added is about 0.2 to 2.5% by weight. Hereinafter, specific embodiments of the high-density information signal recording medium according to the present invention will be described. Example 1 As a thermoplastic resin, for example, vinyl chloride-olefin copolymer VD-10 (manufactured by Mitsui Toatsu Chemical Co., Ltd.)
100 parts by weight, as a conductive substance, for example, conductive carbon black CSX150A2 (manufactured by Cabot Corporation, USA)
20 parts by weight, as a surface lubricant, for example, 0.7 parts by weight of dimethylpolysiloxane SH200 (manufactured by Toray Silicon Co., Ltd.), 6 parts by weight of heat stabilizer SX82HS (manufactured by Daikyo Kasei Kogyo Co., Ltd.)
Part by weight, as fatty acid ester having a hydroxyl group,
For example, a mixture consisting of 1.5 parts by weight of glycerin ester RX-360 (one hydroxyl group in the molecule, manufactured by Daikyo Kasei Kogyo Co., Ltd.) is sufficiently stirred with a high-speed stirrer, and then heated and melt-kneaded with a kneader. For example, a capacitive video disk was produced by extruding the mixture using an extruder and compression molding. Example 2 In Example 1, glycerin ester RX-
A capacitance video disc was produced in the same manner using 3.0 parts by weight of 360. Example 3 In Example 1, glycerin ester RX-
A capacitive video disc was prepared in the same manner using 1.5 parts by weight of glycerin ester S-100 (2 hydroxyl groups in the molecule, manufactured by Riken Vitamin Co., Ltd.) instead of 360. Example 4 In Example 1, glycerin ester RX-
A capacitive video disc was prepared in the same manner using 2.0 parts by weight of ricinoleic acid methyl ester (one hydroxyl group in the molecule) instead of 360. Comparative Example 1 In Example 1, glycerin ester RX-
A capacitive video disc was produced in the same manner without adding 360. Comparative Example 2 In Example 1, glycerin ester RX-
A capacitive video disc was similarly prepared using 1.5 parts by weight of Wax OP (does not contain fatty acid ester having a hydroxyl group, manufactured by Hoechst) instead of 360. Comparative Example 3 In Example 1, glycerin ester RX-
A capacitive video disc was prepared in the same manner using 1.5 parts by weight of G-60 (manufactured by Henkel, Germany) in place of 360. Regarding the capacitive video disk obtained as described above, its processability, for example, the viscosity (fluidity characteristics) measured with a Koka type flow tester (shear rate 10 sec ^-1 ) during heating and melting, Dynamic thermal annealing using Brabender Plastograph, regenerated S/
N. When the same track was reproduced as a still image for one hour, the deterioration in the reproduced image quality (still characteristics) was investigated as shown in the table.

[Table] As described above, in the high-density information signal recording medium according to the present invention, the information signal is recorded as a change in the geometrical shape of the surface portion, and the electrode of the reproducing needle that relatively scans the surface portion and the A high-density information signal recording medium in which an information signal is reproduced by changing the capacitance between the surface portion and the surface portion according to the geometric shape change, and the high-density information signal recording medium is made of thermoplastic resin. , conductive carbon black, and a material containing about 0.2 to 2.5% by weight of a fatty acid ester having a hydroxyl group, this material has a low viscosity when melted by heating, has good fluidity, shortens press time, and is easy to move. It has a long thermal stability, there is no risk of thermal decomposition of the material during kneading, and it has excellent processability, resulting in a correspondingly low cost, and the high density information signal recording medium obtained in this way is It has features such as high reproduction S/N and little deterioration in image quality during still reproduction.

Claims (1)

[Claims] 1. An information signal is recorded as a change in the geometric shape of the surface part, and the capacitance between the electrode of the regeneration needle that relatively scans the surface part and the surface part is determined according to the change in the geometric shape. A high-density information signal recording medium in which an information signal is reproduced by changing the temperature, and the high-density information signal recording medium is made of a thermoplastic resin, conductive carbon black, and about 0.2 to 2.5% by weight of a fatty acid ester having a hydroxyl group. A high-density information signal recording medium characterized by being constructed of a material containing.