JPH052708B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a high-density information signal recording medium such as a video disk or a digital audio disk, in particular, in which an information signal is recorded as a change in the geometrical shape of a surface portion, This relates to a capacitive high-density information signal recording medium in which information signals are reproduced by changing the capacitance between the electrode of a reproducing needle that relatively scans the surface in accordance with changes in geometric shape. be. [Prior art and its problems] Conventionally, pits are formed spirally or concentrically in a plane or groove in accordance with an information signal, and the information signal is recorded as a change in geometrical shape to create an information signal recording medium. A reproducing needle made of diamond or the like provided with an electrode is relatively scanned on the recording track of the information signal recording medium, and the electrostatic capacitance formed between the electrode of the reproducing needle and the information signal recording medium is There is a so-called capacitance reproduction method that reproduces recorded information signals by utilizing changes in response to changes in physical shape. 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 costs. Therefore, a conductive plastic made by mixing several tens of parts by weight of a conductive substance such as carbon black with a resin such as vinyl chloride is press-molded as a raw material, and the information signal is expressed as a change in geometric shape. A recorded capacitive information signal recording medium has been proposed, and since a capacitance is formed between the recording medium itself and the reproducing needle electrode, a metal thin film deposition process is not necessary, and Since the carbon black fine powder particles themselves are coated with resin, there is no need for a dielectric thin film attachment process.
It is said to have the advantage of being extremely easy to manufacture and low cost. However, even with a recording medium made by forming predetermined pits with a resin containing carbon plaque as described above, if it is attached to a playback device and the playback operation is performed for a long time, it may come into contact with the surface of the recording medium. The surface of the recording medium is worn away by the reproducing needle, which changes the shape of the pits, resulting in a change in capacitance, which has the disadvantage that accurate reproduction cannot be obtained. In particular, in the case of still playback, the playback stylus is worn at the same location at a rate of 15 times/sec under a pressure of 400 to 500 kg/ ^cm2 , which causes a large amount of wear on the surface of the recording medium, resulting in the above-mentioned drawbacks. becomes significant. Incidentally, such abrasion of the recording medium occurs not only in the case of still reproduction, but also in normal reproduction, the maximum number of reproductions is less than 100 times. Furthermore, the conventional method has a drawback in that the processability of processing it into a recording medium is not so good. [Disclosure of the Invention] The present inventor thought that as a means to solve the above-mentioned drawbacks, especially the problems on the surface of the recording medium, it would be good to add a lubricant to the recording medium, and based on this idea, However, depending on the type of lubricant used, not only the lubricating effect was insufficient, but also a bleed phenomenon occurred, reducing the quality of the reproduced image. It was also found that there were problems with workability, such as poor kneading conditions in a continuous kneader or extruder, and poor molding in a press molding machine. As a result of further research based on this knowledge, we found thermoplastic resins such as vinyl chloride resins, inductive substances such as carbon black, and alkyl-substituted organopolysiloxanes represented by the following general formula (). It has been found that a capacitive information signal recording medium constructed using a material containing . In the formula, A is a methyl group or (-CH ₂ ) _-P CH ₃ (however,
P is an integer from 3 to 19), B is (-CH ₂ )- _q CH ₃ (however,
q is an integer from 3 to 19), m is an integer from 0 to 100, n is 0
An integer of ~120 (however, if A is a methyl group, it is 2~120)
120), m+n is a natural number of 200 or less. That is, a capacitive information signal recording medium made of a conductive resin composition containing an alkyl group-substituted organopolysiloxane of the general formula () suffers extremely little wear due to contact with a playback needle, and therefore suffers no pit shape deformation. There is almost no oxidation, and a stable reproduction signal can be obtained over a long period of time.Furthermore, it has excellent moldability during molding, and is resistant to staining. In addition, when A and B in the above general formula (I) have too many carbon atoms exceeding 20, the melting point of the alkyl group-substituted organopolysiloxane becomes too high,
This is not preferable because a dusting phenomenon will appear on the surface of the recording medium.
If the sum of and n becomes too large, exceeding 200,
If the molecular weight of the alkyl group-substituted organopolysiloxane increases too much, the compatibility with the resin decreases, moldability deteriorates, and staining phenomena appear on the surface of the recording medium. The content of conductive substances such as carbon black is relatively high, such as several tens of parts by weight per 100 parts by weight of thermoplastic resin, for example, about 125 Ω cm.
It is desirable to have the following volume resistivity, which is an amount that provides the conductivity necessary for the capacitance regeneration method. In addition, the content of the alkyl group-substituted organopolysiloxane represented by the general formula () is
The amount is preferably about 0.3 to 2.0 parts by weight per 100 parts by weight. In addition, the viscosity (25°C) of the alkyl group-substituted organopolysiloxane represented by the general formula () is approximately
It is desirable that it be less than 10000cs. Examples 1 to 8 PVC with an average degree of polymerization of 500 and an EVA content of 3%.
100 parts by weight of EVA craft copolymer (Tose Ace GK manufactured by Tokuyama Sekisui Kogyo Co., Ltd.), dibutyltin mercaptoester stabilizer (RES-1 manufactured by Sankyoki Gosei Co., Ltd.)
7 parts by weight, higher fatty acid glycerin ester lubricant (RES-210 from Riken Vitamin Co., Ltd.), 2 parts by weight, higher fatty acid alkyl ester lubricant (Kao Soap Co., Ltd.)
0.5 parts by weight of RES-310) and 1 part by weight of alkyl-substituted organopolysiloxanes represented by general formulas () of Nos. 1 to 8 shown in the table were blended at high speed and heated to 110°C in a Henschel mixer. After that, it was cooled at low speed to 70℃, then 20 parts by weight of conductive carbon black (CSX-150A3 manufactured by Cabot, Inc., USA) was added, and the temperature was raised again at high speed to 110℃, thoroughly stirred, cooled, and then heated to 110℃. company kneader PR
-46 to make pellets. Then, metal foreign matter contained therein is removed using a metal detector, and a capacitive video disc is obtained using a press machine exclusively for video discs.

[Table] Comparative Examples 1 to 4 In Example 1, instead of the alkyl group-substituted organopolysiloxane No. 1 in Table 1, A and B in the general formula () are epoxy groups.

[Formula] or beauty salon group

[Formula] or

Video discs are obtained in the same manner using epoxy group- or ester group-substituted organopolysiloxanes No. 1 to 4 shown in Table 2 having the formula:

[Characteristics test]

Attach the capacitive video disc obtained in each of the above examples to a playback device, and check the Y-S/N in gray IRE according to the NTSC system recorded at the 54th minute position on the inner circumference of the signal section of the video disc. The pass rate was determined by measuring the degree of Y-S/N degradation when stills were reproduced during measurement. That is, prepare 10 to 12 video disks for each row, measure each video disk three times with different tracks, and calculate Y-S/N.
Those with a degree of inferiority within 3 dB are considered to be passed, and those with a degree of inferiority of 3 dB or more or needle skipping are considered to be rejected.The pass rate is determined and the results are shown in Table 3. Table 3 shows the moldability of each of the above arrangements into a video disc.

【table】

【table】

Claims (1)

[Claims] 1. An information signal recording characterized in that the information signal recording medium is made of a material containing a thermoplastic resin, a conductive substance, and an alkyl group-substituted organopolysiloxane represented by the following general formula (). Medium. (However, A is a methyl group or a linear alkyl group having 4 to 20 carbon atoms, B is a linear alkyl group having 4 to 20 carbon atoms, m is an integer from 0 to 100, and n is an integer from 0 to 120 ( However, if A is a methyl group, 2 to 120), m+n
is an integer between 0 and 200. )