JPS61153855A - Information recording carrier - Google Patents

Abstract

PURPOSE:To obtain a capacitance system information recording carrier having especially superior wear resistance and giving a high quality image by using electrically conductive carbon black by a specified amount basing on the amount of a polyvinyl chloride - ethylene vinyl acetate copolymer. CONSTITUTION:Electrically conductive carbon black is added to a polyvinyl chloride - ethylene vinyl acetate copolymer by 22-26 parts per 100 parts copolymer, they are mixed with a heat stabilizer, a lubricant, lubricating oil, etc., and the mixture is well kneaded and pelletized. The pellets are press-molded with a stamper to obtain a capacitance system information recording disk. The copolymer used has 99.5:0.5-70:30 weight ratio of vinyl chloride:ethylene vinyl acetate and 300-650 average degree of polymn., and the electrically conductive carbon black used has 800-1,500m<2>/g specific surface area measured by a nitrogen adsorption method, 250-480ml/100g extent of DBP oil absorption and <=3wt% ash content. The resulting disk has especially superior wear resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a capacitance conversion type information recording carrier, and more particularly to a capacitance conversion type information recording carrier having excellent information recording and reproducing performance.

[Technical background of the invention and its problems] Capacitance conversion type information recording carriers have been developed and put into practical use as record carriers for recording audio, video, etc. This record carrier is made of a molded body (disk) made of a resin composition containing a conductive substance such as carbon black, and has numerous fine holes (bits) on which information such as audio and video is stored on the surface of the disk. A reproducing needle with a metal electrode is brought into contact with this recording surface.
It moves to read the spatial volume due to these uneven shapes as changes in capacitance, and reproduces audio, video, etc.

By the way, in this capacitive information recording carrier,
The properties of the base material, conductivity imparting agent, and various additives have a great influence on the information recording and reproducing performance of the record carrier.

That is, in such an information recording carrier, since information is read through contact and movement between the reproducing needle and the molded disk, the material is particularly required to have wear-resistant properties.

Conventionally, such information recording carriers have not been able to withstand long-time reproduction, and there has been a strong desire to improve this point.

[Object of the Invention] An object of the present invention is to meet such demands and provide an information recording carrier with excellent wear resistance.

[Summary of the Invention] That is, the information recording carrier of the present invention has a material composition of 100 parts of polyvinyl chloride (PVC)-EVA (ethylene vinyl acetate) copolymer, 22 to 26 parts of conductive carbon black, and Other additives are a heat stabilizer, a lubricant, and a lubricating oil.

[Embodiments of the Invention] The resin used as the base material of the information recording carrier has properties such as high fluidity, heat softening resistance, lubricity, mechanical strength, thermal stability, high purity, transferability, and abrasion resistance. characteristics are required. That is, in principle, a capacitance converting type recording carrier must have a volume resistivity of about 102Ω or less, and therefore powdered conductivity imparting material such as carbon black must be added and mixed especially during winter. No. Therefore, the thermal fluidity of the mixture inevitably decreases, and the moldability and bit transferability tend to deteriorate. To improve this, the resin itself is required to have high fluidity. Furthermore, since the base material has such a high filler content, it tends to become brittle, and when mixed and crossed, the temperature rises abnormally due to self-heating, which tends to cause thermal decomposition and thermal deterioration. Therefore, the resin itself is required to have strong mechanical strength and high thermal stability.

On the other hand, this information record carrier detects information and electrically outputs audio and
Since it is used in equipment (player) that converts images, etc., it must have sufficient heat softening resistance against the heat generated by the player, and is usually 60°C or higher (C
1ash & Bera method) heat softening resistance is required.

Furthermore, since the information recording carrier detects information by contacting and acting with a detection needle at high speed, characteristics such as III purity and abrasion resistance are also required. Furthermore, if impurities are present in the base material, minute protrusions will occur on the surface when molded, causing the detection needle to jump and causing information to be lost.

As mentioned above, there are many performances required of the base material, so
As in the present invention, it must be a limited resin. That is, a polyvinyl chloride-EVA copolymer is suitable, and preferably the ratio of vinyl chloride to EVA is 99.5:
A polyvinyl chloride-EVA copolymer having a weight ratio of 0.5 to 70:30 and an average degree of polymerization of 300 to 650 is suitable.

As for conductive carbon black, it is naturally necessary to exhibit high conductivity (volume resistivity of 1020 υ or less) when mixed and kneaded, and it is also required to have moldable fluidity.

Furthermore, when converted into a video image, it must be a highly detailed image, and of course it must contain as few impurities as possible.

As a result of intensive research, the inventors have found that the higher the carbon black addition rate, the better the image quality and at the same time the abrasion resistance against the recycled needle.

In particular, it has been found that when the amount is 22 parts or more, it has excellent wear resistance properties. However, when the amount exceeds 26 parts, the amount of filler is too large and the fluidity is extremely reduced, making molding virtually impossible.

Therefore, an appropriate addition rate is 22 to 26 parts of conductive carbon black to 100 parts of polyvinyl chloride-EVA copolymer, and within this range, molded bodies (discs) with particularly excellent wear resistance can be produced. I was able to get it.

In addition, the characteristics of the carbon black used at this time include a specific surface area of 800 to 1500 m/y (nitrogen adsorption method), D
Those with physical properties of BP oil absorption of 1250 to 480 (#+1!/100g) and ash content of 3 wt% or less had good image quality and were excellent information recording carriers.

Regarding thermal stability, this type of material is generally highly filled with carbon black, so it generates a large amount of self-heating during molding, and the carbon black acts as a catalyst, making it a material that is prone to thermal decomposition. I can say that. Therefore, it is necessary to use a strong stabilizer during production, and it is preferable to carry out the production under as mild conditions as possible.

Other additives include lubricants and cleaning oils. This works to suppress abnormal heat generation during kneading, and also causes some bleed out of the molded product surface on the surface of the molded product, thereby reducing friction and wear between the molded product and the detection needle.

If the amount of these components is too small, the above-mentioned function will be insufficient, and if the amount is too large, the heat softening resistance will decrease, the transferability will decrease (deterioration of bit moldability), and the molding yield will decrease due to contamination of the mold (stand bar). causing deterioration and other disorders.

In order to explain the present invention more specifically, Examples are given below.
Although the present invention will be explained using comparative examples, the present invention is not limited to these examples.

11A1-4 Comparative Examples 1-4 10 kg of polyvinyl chloride resin was weighed and placed in a Henschel mixer (manufactured by Mitsui Miike Seisakusho) and stirred. Immediately, predetermined amounts of stabilizer, lubricant, and lubricating oil are added and mixed at high speed rotation. 60-8
After reaching 0° C., the stirring is temporarily interrupted, a predetermined amount of carbon black is added, and the mixture is stirred and mixed again at high speed rotation.

In this way, when the temperature reaches 90-110℃, high-speed mixing is finished,
Perform cooling operation at low speed. Once cooled to about room temperature to 50°C, the mixed powder is discharged from the Henschel mixer.

Next, the mixed powder was cross-mixed using a Konida cross-mixing machine (manufactured by Buss), and simultaneously formed into pellets to obtain a resin material for press molding.

On the other hand, audio and video are converted into countless bits by laser cutting, and the recorded master disc is copied from master to mother to standby using a plating process, similar to the process of audio records, and directly reproduced. I got a mold, a stanbar.

Using these materials and a stand bar, a capacitance conversion type information recording carrier was produced by molding with a press molding machine. Table 1 lists the characteristics of the information recording carrier thus produced.

Next, each item in Table 1 will be explained.

+1) CNR...Carrier noise ratio ((:, a
noise ratio).

(2) Wear resistance characteristics...Still:
Disc life characteristics evaluated by static image) test, repeat (Repeat) test, etc.

(3) Fluidity: Measured using a Koka type flow tester.

(4) Thermal stability: Static thermal stability using Fungo Red test paper.

(5) Heat softening resistance...crush and barb (CI)
ash & Berg) flexibility test method used.

(6) Mechanical strength: Mainly dynestat (D
ynstat) according to the impact test method.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a capacitive heavy type information recording carrier with excellent wear resistance.

Claims (2)

[Claims] (1) In an information recording carrier composed of polyvinyl chloride-ethylene vinyl acetate copolymer, conductive carbon black, a heat stabilizer, a lubricant, and a lubricating oil, 100 parts of polyvinyl chloride-ethylene vinyl acetate copolymer An information recording carrier having excellent abrasion resistance, characterized in that the proportion of conductive carbon black is 22 to 26 parts. (2) As a polyvinyl chloride-ethylene vinyl acetate copolymer, the ratio of vinyl chloride to ethylene vinyl acetate is 99.5:0.5 to 70:30 (by weight),
Use carbon black with an average degree of polymerization of 300 to 650, and a specific surface area (nitrogen adsorption method) of 800 as conductive carbon black.
~1500m^2/g, DBP oil absorption 250~480m
1/100g and an ash content of 3 wt% or less.