JPS647409B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a conductive disk in which pits corresponding to information signals are formed on the surface at predetermined intervals in a spiral or concentric manner. Generally speaking, capacitance is a capacitance that can be extracted as an information signal by changing the capacitance between the playback needle, which has a conductive layer formed on its side surface, and the conductive disc, depending on the length between pits or pits. The present invention relates to a conductive disk-type record carrier called a method. Conventional structure and its problems In recent years, as a conductive disk type record carrier that can be reproduced using this type of capacitance method, CED method video disk (with a guide groove for the reproducing needle; US
RCA), VHD format video discs (no playback stylus guide groove; Japan Victor Co., Ltd.), and AHD format digital audio discs (no playback stylus guide groove; Japan Victor Co., Ltd.) were not announced or commercially available. ing. In any of the above methods, the same material composition can be used, and the same can be said for the manufacturing method. Therefore, it goes without saying that the present invention is effective in any system. Hereinafter, conventional examples of conductive disk type record carriers and their problems will be described. Conventionally, in the field of the record industry, in order to obtain discs, disc records are produced by compression molding a composition mainly consisting of vinyl chloride resin and other additives, using a stamper with information signals on the surface. It is being produced. On the other hand, the kneading technique and molding technique common to conventional audio record discs can be used in the manufacturing method of capacitive conductive disk type recording carriers.
Since disc materials are required to have appropriate flexibility and wear resistance, vinyl chloride resin materials are used as disc molding resin materials. However, in such conductive disk-type record carriers a sufficient amount of conductive particles must be incorporated to enable capacitive reading from the disk. As conductive particles, processability,
It is preferable to use conductive carbon black from the viewpoint of dispersibility, stability, cost, etc., and the amount added is such that the volume resistivity of the disk is less than 500Ω・cm, preferably several
An amount of 10Ω・cm or less is required. moreover,
The difference from conventional audio record materials is that signals (pits) with a diameter of approximately 1 micron must be faithfully reproduced by press, so despite the inclusion of a large amount of carbon black, the composition is not brittle and melts easily. Fluidity must also be appropriate, continuous pressing is possible without contaminating the stamper, and there is little wear and damage to the disk or recycled needle due to dynamic friction that occurs between the disk and the recycled needle during disk recycling. For example, quality requirements are higher than for conventional records. In order to satisfy these quality requirements, many proposals have been made for resin materials as disk materials.For example, as resin materials, the above-mentioned vinyl chloride resin materials include straight vinyl chloride resin and chlorinated polyethylene resin. Copolymer resins of vinyl chloride and olefins such as ethylene and propylene, and graft polymerization of vinyl chloride to ethylene/vinyl acetate copolymers are known. Further, as the conductive carbon black, one that has good kneadability with the resin material and has low electrical resistance is used. When a vinyl chloride resin is used as the resin material, a heat stabilizer is used to prevent thermal decomposition of the resin material during kneading, extrusion, and molding. Furthermore, a lubricant (processing aid) is used to lower the melt viscosity of the resin material and improve moldability. Furthermore, it reduces the adhesion to the inner walls of the kneader and extruder during kneading and molding of resin materials, improves mold release in press machines, and reduces the dynamic friction that occurs between the disc and recycled needle. Wetting agents are used to prevent wear and damage. Among these, the selection of lubricant is extremely important for the conductive disk-type record carrier that is the object of the present invention. This is because the relative speed difference between the disk and the playback needle during disk playback is extremely large (the disk rotation speed is 450 revolutions per minute in the CED system, VHD
900 revolutions per minute) and requires trick play such as still playback, slow playback, high speed playback, and random access playback, which is an extremely disadvantageous condition when considering the wear resistance of the disk and playback needle. This is because it is getting older. In general, lubricants are known to be based on inorganic materials or organic materials. Inorganic materials include graphite molybdenum disulfide, while organic materials include higher fatty acids, higher fatty acid salts, higher fatty acid esters, etc.
Paraffin hydrocarbon compounds and silicone oils (eg dimethylpolysiloxane, methylphenylpolysiloxane, etc.) are known. The selection of lubricants in disk materials depends on their dispersibility, thermal stability,
Silicone oils such as dimethylpolysiloxane and methylphenylpolysiloxane have been used due to their practical effects. As a result, the wear resistance of the disk has improved considerably, but the wear resistance of the regenerated needle has not been significantly improved, and there has been a strong desire for a lubricant that is also effective in reducing the amount of wear on the regenerated needle. OBJECTS OF THE INVENTION An object of the present invention is to provide a conductive disk-type record carrier that has excellent abrasion resistance and has significantly improved abrasion resistance of a reproducing needle. Structure of the Invention The conductive disk-type record carrier of the present invention is constructed using at least a thermoplastic resin and conductive carbon black particles, and pits corresponding to information signals are formed at predetermined intervals in a spiral shape or on concentric circles. At the same time, the thermoplastic resin has a vinyl chloride resin and a general formula [In the formula, R represents an alkyl group having 2 to 15 carbon atoms, and R' represents a methylene group having 2 to 4 carbon atoms.
The sum of x and y indicates the degree of polymerization of the siloxane bond,
30≦x+y≦70. ] Contains an alkylaralkyl-modified silicone represented by
The content is 0.6 to 1.2 parts by weight, and as a result, the resulting conductive disk-type record carrier has good abrasion resistance, and the abrasion of the reproducing needle can be significantly reduced. Considering the reason why a disc made of vinyl chloride resin mixed with a modified silicone having an alkyl or aralkyl group in the side chain represented by the general formula () has extremely good durability against discs and recycled needles. Compared to silicone oils represented by dimethylpolysiloxane or methylphenylpolysiloxane, the alkylaralkyl-modified silicone represented by the general formula () used in the present invention is
If R and R' have carbon numbers of 2 to 15 and 2 to 4, respectively, they have relatively good compatibility with vinyl chloride resins and are numbers that indicate the degree of polymerization x
If +y is 30 to 70, there will be some bleed to the surface during use of the disk, and furthermore, a phenyl group has been introduced into a part of the structure, so it is more heat resistant than dimethyl silicone oil. However, it is thought that it has a great effect as a lubricant, that is, on initial properties, durability properties, and environmental test properties. DESCRIPTION OF EMBODIMENTS The present invention will be specifically described below with reference to Examples. In addition, all the parts mentioned in the following examples show parts by weight. Example 1 Vinyl chloride resin (straight vinyl chloride resin average degree of polymerization 450)...100 parts Chlorinated polyethylene (manufactured by Showa Voltage Co., Ltd., Elastrene 301A; chlorine content 30%)...4 parts Conductive carbon black ( Manufactured by Cabot Inc., USA
CS x 150A-3, DBP oil absorption approximately 320cc/100g, average particle size 16-18μm, apparent specific gravity approximately 0.13)...20 parts Heat stabilizer A (manufactured by Nitto Kasei Kogyo Co., Ltd., N2000K; organic tin-based liquid Stabilizer) Heat stabilizer B (manufactured by Nitto Kasei Kogyo Co., Ltd., MA300A; dibutyltin malate)...2 parts Lubricant A (manufactured by Henkel Nissui Co., Ltd., Roxiol G-
60; Diacid ester of aliphatic alcohol, melting point
42-46℃)...2.0 parts Lubricant B (manufactured by Henkel Nissui Co., Ltd., Roxiol G-
70; Polymer ester wax, melting point 50-52℃)...
…0.4 parts Lubricating oil (manufactured by Toray Silicone Co., Ltd., SH-203; alkylaralkyl-modified silicone oil represented by the general formula (), viscosity 1200 cps, specific gravity 0.91, refractive index
1.464)...0.7 part The mixture consisting of the above composition was sufficiently stirred with a high-speed stirrer, then heated and melted and kneaded with a kneader, and then extruded and compression molded to prepare a sample disk. Examples 2 to 4 In Example 1, the amount of alkylaralkyl-modified silicone oil, SH203, added as a lubricating oil was 0.6
Samples were prepared in exactly the same manner as in Example 1, except that 1 part (Example 2), 0.9 parts (Example 3), and 1.2 parts (Example 4) were used. Comparative Example 1 In Example 1, dimethyl silicone oil (manufactured by Toray Silicone Co., Ltd., SH200; viscosity:
A sample was prepared in exactly the same manner as in Example 1, except that the amount added was 0.7 parts. Comparative Example 2 In Example 1, phenyl-modified silicone oil (manufactured by Toray Silicone Co., Ltd., SH550; methylphenyl-modified silicone oil, viscosity 130 cps) was used instead of the alkylaralkyl-modified silicone oil as the lubricating oil, and the amount added was 0.7 parts. A sample was prepared in the same manner as in Example 1 except for the above. Comparative Examples 3 to 5 In Example 1, the amount of alkylaralkyl-modified silicone oil and SH203 used as the lubricating oil was 0 parts (Comparative Example 3), 0.3 parts (Comparative Example 4), and 1.5 parts (Comparative Example 5). A sample was prepared in exactly the same manner as in Example 1. The samples obtained in the above Examples and Comparative Examples were examined for moldability, raw image quality, and abrasion resistance of disks and regenerated needles. The results are shown in the table below.
In addition, the volume resistivity values of the samples are all 8~
It was 12Ω・cm.

[Table] In the above table, (1) The amount of silicone oil added is
The number of parts by weight of silicone oil added per 100 parts by weight is shown. (2) Moldability was evaluated using a stamper during hot compression molding of a kneaded disk material of a predetermined composition, the dirtiness of the disk surface, the organic content of the disk warp, etc. (3) The wear resistance of the disk was determined by regenerating the steel of the middle circumference of a sample disk of a specified composition for one hour.
The presence or absence of deterioration in the playback image quality and the degree of damage to the disk surface caused by the playback needle were examined. (4) The life of the regenerated needle was measured by repeatedly regenerating the sample disk over the entire circumference and measuring the time until the length of the regenerated needle decreased by 2.5 μm. Effects of the Invention As is clear from the above description, the disk-type record carrier of the present invention is constructed using at least a thermoplastic resin and conductive carbon black particles, and pits corresponding to information signals are formed in a spiral or concentric shape. The thermoplastic resin includes a vinyl chloride resin and an alkylaralkyl-modified silicone represented by the general formula (), and the component composition ratio and the vinyl chloride resin are formed at predetermined intervals.
It is characterized in that the alkylaralkyl-modified silicone is present in an amount of 0.6 to 1.2 parts by weight per 100 parts by weight, and conventional dimethyl silicone oil,
It becomes possible to produce a conductive disk recording carrier that has excellent abrasion resistance, especially the abrasion resistance of the regenerated needle, compared to those to which methylphenyl-modified silicone oil is added.

Claims (1)

[Scope of Claims] 1 It is constructed using at least a thermoplastic resin and conductive carbon black particles, and pits corresponding to information signals are formed at predetermined intervals in a spiral or concentric shape, and The resin is vinyl chloride resin and the general formula [In the formula, R represents an alkyl group having 2 to 15 carbon atoms, R' represents a methylene group having 2 to 4 carbon atoms,
30≦x+y≦70. ] A conductive disk-type recording carrier comprising an alkylaralkyl-modified silicone represented by the following formula, and having a component composition ratio of 0.6 to 1.2 parts by weight of the alkylaralkyl-modified silicone per 100 parts by weight of the vinyl chloride resin.