JPS59119553A - Manufacture of discoid recording medium - Google Patents

Abstract

PURPOSE:To obtain a highly reliable discoid recording medium free from swelling due to impurity on the surface by applying preliminarily stabilizing processing to conductive carbon black which is added to resin. CONSTITUTION:Conductive carbon black is heat treated in the atmosphere of inert gas of 550-850 deg.C. Then, it is heat treated in the current of 300-850 deg.C that contains carbon dioxide gas and water vapor. The carbon black is cooled and washed with weak hydrochloric acid and water and dried. Then, a conductive material is prepared by mixing the refined carbon black with thermoplastic resin. This is shaped and a discoid recording medium that forms pits 3 that correspond to information signals swirlingly or concentrically at specified intervals is formed. Carbon black is added suitably to the resin in the proportion that makes the volume specific resistance of formed product desirably <=100OMEGA. cm, and desirable quantity of added carbon black is 10-40pts.wt. to 100pts.wt. of the disk forming resin.

Description

[Detailed Description of the Invention] Fields of application in the pressure industry: A method for producing a disk-shaped recording medium using black, such as a star-shaped video disk. Regarding.

Conventional configuration and its problems Traditionally, in the field of audio record industry,
For example, using a stamper with information signals on the surface,
Disc records are mainly produced by compression molding a copolymer of vinyl chloride and vinyl acetate.

On the other hand, disk-shaped recording media using conductive materials, such as static capacitive video disks, are manufactured by almost the same manufacturing method as the one described above, and have the shapes shown in FIGS. 1 to 8. I'm getting a disc. In the figure, (1
) is a disk-shaped disk, and (2) is this disk-shaped disk (1
), (3) is a circular disk (1
) is a pit corresponding to the information signal J provided on the surface.

When such a conductive disk is placed on a Brayer's rotating system and rotated, and a needle with a metal electrode is placed on the disk surface with pits, information is transferred to the electrostatic capacitor according to the pits carved on the disk surface. Obtained as a change 1) Life is carried out.

Unlike conventional audio records, electrostatic capacitive disk-shaped recording media have sufficient conductivity on the disk.
Therefore, a considerable amount of conductive carbon black particles must be mixed into the resin material.
However, various problems may occur depending on the physical and chemical characteristics of the disk.

For example, if carbon black contains a large amount of impurities, these impurities will cause various defects such as protrusions on the surface of the disc, which may prevent playback or damage the stamper. damage or cause damage. That is,
Blisters occur in the areas of the disc containing these solid substances, and when played by a player, these bulges can cause the needle to jump or cause poor tracking.Furthermore, if the needle jumps, subsequent discs may The surface of the C disk will be damaged when falling onto the surface.

In view of these points, when observing the surface of a disk obtained by kneading a highly conductive carbon black and a resin with an optical microscope, it was found that the diameter was more than 10 microns. In addition, when this disc was played by a player, white precipitate scratches were found, extending several hundred microns away from the scratches. It was observed that needle scratches were again etched in the locations of .These needle scratches grew as the number of performances increased, and at the same time, the image quality of the reproduced video deteriorated.

According to X-ray microanalyzer analysis 1ξ, these white precipitates are composed of calcium (Ca) and TtG yellow (S).
It was recognized that this includes On the other hand, X-ray analysis revealed that the main component of ash obtained when carbon black was heated to 650°C in the atmosphere and burned was calcium sulfate (CaSO).
It became clear that it was an anhydrous salt of 4). Although it is extremely difficult to analyze the form in which calcium (Ca) and sulfur (S) exist in carbon black,
Those containing calcium and sulfur include calcyano sulfide (las), calcium thiosulfate CCa520B)
and calcium sulfate (CaSO4) and water containing it. In addition, sulfur is considered to be combined with the free P1 yellow and carbon.

By the way, when carbon black is heated in various atmospheres, it produces 7riE acid gas (502) and hydrogen sulfide (H2S).
), carbon disulfide (C52), carbon oxysulfide (CO5
) It has become clear that various sulfur compounds are generated in the form of The rate at which these gases are generated depends on the temperature and the type of atmospheric gas. These impurities in carbon black are thought to be mixed in from the petroleum itself, which is a raw material, or from the cooling water used during the manufacturing process, and even carbon black manufacturers are making efforts to reduce the amount of impurities. ≦, it is difficult to fully exclude it in relation to the H construction cost.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art.In order to solve the above-mentioned drawbacks of the conventional technology, the conductive carbon black added to the resin is subjected to a stabilization treatment in advance.
The object of the present invention is to manufacture a highly reliable disk-shaped recording medium with no blistering caused by impurities on the surface (WI2 'f').

Structure of the Invention In order to achieve the above-mentioned object, the method for manufacturing a disk-shaped recording medium of the present invention includes a method for manufacturing a disk-shaped recording medium of the present invention.
Heat treated in an inert gas atmosphere at 50℃, 800℃
The carbon black was heat treated in an air stream containing carbon dioxide gas and water vapor at ~850°C, then cooled, washed with weak hydrochloric acid and water, dried, and then dried to obtain purified carbon black. A conductive material is produced by kneading the adhesive and a plastic resin, and then this conductive material is molded to form bits corresponding to the ζ-1 information signal 4L at predetermined intervals in a spiral or concentric pattern. The disk recording medium is constructed in an I-shaped structure, thereby making it possible to manufacture a disk-shaped recording medium with excellent playback characteristics and no bulges on the surface due to impurities.

DESCRIPTION OF EMBODIMENTS The structure of the method of the present invention will be described below based on one embodiment thereof. The shape 1j of the disk-shaped recording medium manufactured by the method of the present invention is the same as that shown in FIGS. 1 to 103 above.

First, examples of thermoplastic resins that can be used in the method of the present invention include vinyl chloride, vinyl chloride/vinyl acetate copolymer,
Vinyl chloride/ethylene copolymer, vinyl chloride/propylene copolymer, vinyl chloride.

(meth)acrylic acid alkyl ester copolymer, acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer, acrylonitrile-styrene-ethylene copolymer, methyl methacrylate, rylate,
Examples include methyl methacrylate/butadiene copolymer. It goes without saying that a heat stabilizer, a plasticizer, and a moisturizing agent may be used together with these thermoplastic resins as necessary. Furthermore, regarding the addition rate of carbon black to the resin ζC used in the method of the present invention, it must be added in an amount that provides sufficient conductivity to enable electrostatic capacitance reading from the disk. As a guideline, the external resistivity of the molded product should be less than 100 Ω·an, preferably less than 100 Ω·an. These conditions are '6'
The amount of carbon black added in the conductive fine particle binding process suitable for adding t1 is 10 to 40 parts by weight, preferably 15 to 85 parts by weight, per 100 parts of the disk-constituting resin. The amount of carbon black added is 15%, especially 10%.
If the amount is less than 1 part by weight, the conductivity of the disk cannot be sufficiently increased. On the other hand, if the amount added is 85 parts by weight or more, especially 40 parts by weight or more, the processability of the kneaded product decreases and the brittleness of the finished disk does not increase, making it unsuitable for practical use.

Next, specific examples and comparative examples of the method of the present invention will be explained.

(Example 1) Particle diameter 20 mμ (electron microscopy), surface area (nitrogen adsorption method) 1580 mVg, oil absorption m (D B P ) s
som (3/100 gSPH8.5, ash 0.98
% conductive carbon black (manufactured by Cabot) 20
0 g was placed in an alumina boat, placed in the core tube of a tube furnace, and heat-treated in a stream of nitrogen gas fed from one end of the tube furnace. The temperature of carbon black in this case was about 700°C. Next, the carbon black was naturally cooled, and nitrogen gas containing carbon dioxide and water vapor was fed from the CC.

At this time, hydrogen sulfide (H
2S) was observed. The generation of hydrogen sulfide was completed after more than 2:1 h of treatment, and the heat-treated car pump tank was cooled, soaked in dilute hydrochloric acid solution several times, and then washed with pure water 8 to 4 times. Then, it was dried to obtain purified carbon black.

The ash content of carbon black after heat treatment and washing was approximately (1.05%). Also, as a result of X-ray diffraction, the main component of the crystal phase of the ash content of carbon black without heat treatment was found to be 1.05%. Although it was calcium sulfate (CaSO4), the main component of the ash in the heat-treated carbon black was calcium carbonate (CaCOs).The pH of the heat-treated carbon black was 9.2.

Next, the above treated carbon black...2
0 parts vinyl chloride/lauryl acrylate copolymer ((composition ratio 95:5, degree of polymerization 480)...ioo
Part stabilizer (Sankoki ((ceramic, Stan JF-20.)
・・・・・・・・・・・・・・・・・・ 8 parts lubricant (11 bottles manufactured by Henkel, LoxiolGE-2)...
・・・・・・・・・・・・・・・・・・・・・・・・
... A mixture consisting of two parts was thoroughly mixed using a high-speed stirrer, then melt mixed using hot rolls, and then compression molded to produce a disk.

(Comparative Example 1) Using untreated carbon black that had not been heat-treated, a disk was manufactured in the same manner as in Example 1 at °C, and the surface was observed.

Example 1 and Comparative Example 1"'C The obtained discs immediately after compression molding were observed using an optical microscope and foreign matter analysis was performed using an X-ray microanalyzer. Furthermore, the discs that had been played several times using a player were also examined. Surface observation was conducted.No large precipitates were found on the surface of the heat-treated disk to which carbon black was added, but on the surface of the disk to which untreated carbon black was added. A large number of white precipitates were observed.According to the X-ray microanalyzer, the main components of the white precipitates were sulfur (S) and calcium (Ca), so this precipitate was considered to be CaSO4.

This white precipitate catches the needle when playing on the player and causes the sword to jump, but it does not cause dropouts.
" is approximately one horizontal scanning time.

On the disc of the comparative example, which was played several times using a brake player, there were needle scratches above the white precipitate, and scratches due to needle skipping were observed behind the white precipitate. Furthermore, the scratches caused by this needle skipping grow with each performance.
In the end, it was recognized that the scratches at the end (i) were connected after going around the disk.

(Example 2) Particle size 20 ml (TiL particle microscopy), surface area (nitrogen adsorption method) 1850 mV'g, (1'H' (oil j-1 (D B P ) FJ20 ml/11) Og
200 g of conductive 7U carbon flux (manufactured by Cabot) with 1P H8.0 and ash content of 1.52% was placed in a quartz board and placed in the core tube of a tube furnace, and placed in a stream of argon gas fed from one end of the tube path. Heat treatment was performed. The temperature of the carbon black at this time was about 600°C.

. Next, this carbon black was naturally cooled to
'C about 400"C, JK,!After descending, the tube furnace-
A mixture of nitrogen and carbon dioxide gas (6%) containing moisture is pumped in from the pan. At this time, the gas flowing out from the other end of the tube furnace is introduced into a washing bottle containing water, and hydrogen sulfide (H2S) is removed.
was quantified. Next, the heat-treated carbon black was cooled, washed several times by immersing it in dilute hydrochloric acid solution, and then washed 8 to 4 times with pure water. Then, it was dried to obtain purified carbon black. Incidentally, the ash content Ji'' of the carbon black that underwent heat treatment and washing was about 0.09%. In addition, as a result of X-ray diffraction, the ash crystals of carbon black that have not been heat-treated are mainly composed of calcium sulfate (Ca5O4),
Although the secondary component was sodium chloride (NaCn), the main component of the ash of the heat-treated and washed carbon black was calcium carbonate (CaCOa), and P11 was 9.2. Next, a disk was manufactured in the same manner as in Example 1 using the carbon black that had undergone this heat treatment and cleaning treatment. (Comparative Example 2) The raw carbon black used in Example 2 was not heat treated, In the same manner as in Example 1, insert the disk into C'.
It was extended.

(Comparative Example 3) The heat treatment method was almost the same as in Example 2, and a disk was also manufactured by mixing the tube in the furnace and carrying out the ``X'' test ``C times''.
child .

As a result of observing the surface +i+i of each disc in Example 2 and ratio 1 bite cases 2 and 8 with an optical microscope, the actual h1
In the disk of Example 2, the force is hardly observed and the force is ≦.
A white precipitate was observed at t3. Furthermore, when playing these discs on a brake player, the needle skipping force caused by the deposits was observed.

Next, the discs obtained in Example 2 and Comparative Examples 2 and 3 were placed in a constant temperature and humidity chamber at 40°, 095% RH, and exposed at 72 o'clock for 1 d. In the disks, almost no blisters were observed on the surface; however, in the disks of Comparative Examples 2 and 3, blisters with a size of 80 to 50 m, which caused moisture absorption, were observed.

(Section 1i; q <3'll 4.) The heat treatment method was almost the same as in Example 2, but the experiment was conducted by changing only the gas flowing into the furnace tube.

That is, after conducting a similar experiment by mixing a small amount of air in addition to water vapor and carbon dioxide gas flowing from one end of a tube furnace toward carbon black at 400°C, Discs were manufactured using carbon black.

Solid precipitation was also observed on the surface of the disc manufactured in Comparative Example 4, which caused needle skipping during performance.

(Comparative Example 5) The heat treatment method was almost the same as in Example 2, and 11 disks were manufactured using a certain amount of force and using carbon black without cleaning after the heat treatment.

Regarding the disk manufactured in Comparative Example 5, solid precipitation was also observed on the surface, and blistering occurred due to moisture absorption when left in humidity for a long time.

Please show the above two examples and five comparative examples.
It is clear that when discs are manufactured using PI binding, solid precipitates are obtained on the disc surface, which causes dropouts and disc deterioration.
It was. As long as carbon black contains such impurities, it is considered difficult to prevent the precipitation of impurity facets on the disk surface.

In other words, in order to prevent the precipitation of impurity facets, carbon stage 1
If '-(L' It is desirable to keep the impurity at Jl. Therefore, in the method of the present invention, first, 1; +
The material was subjected to X treatment to transform impurities into substances that are easily soluble in acid and water, and then washed.

Incidentally, the initial heat treatment of the "t" pouring carbon black, 1iIi degree, is suitably 550°C to 850'C. 550°CIL 7Ait, 850°C
Calcium sulfate (
1 (Ca5O4) occurs.The second heat treatment temperature is preferably 800°C to 850"C.If the temperature is less than 800°C or exceeds 850°C, hydrogen sulfide ( This is because the generation of H2S is small and a partial reaction rate can be obtained.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(It is possible to manufacture a disk-shaped recording medium with excellent reproduction characteristics without any swelling due to adhesive substances on the surface.

(2) Therefore, needle dropout, needle skipping, etc. can be prevented, and the reliability, quality, and manufacturing cost of the disk can be greatly improved.

[Brief explanation of the drawing]

The drawings show the shape of a disk-shaped recording medium, and FIG. 1 is a top view of the disk to which the method of the present invention is applied, and FIG.
FIG. 3 is a partially enlarged view showing a part of the disk surface of FIG. 1, and FIG. 3 is a sectional view of FIG. O)... Disc-shaped disk, (2)... Center hole, (3
)···bit. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. Conductive carbon black from 550°C to 850°
After heat treatment in an inert gas atmosphere of 800°C
The purified carbon black obtained by heat treatment in an air stream containing carbon dioxide gas and water vapor at ~850°C, then cooling, washing with weak hydrochloric acid and water, and drying. A conductive material is produced by kneading thermoplastic disease JJd, and then this conductive material is molded to form pits corresponding to the information (Th number) in a spiral or concentric manner at predetermined intervals. 1. A method for manufacturing a disc-shaped recording medium, the method comprising: manufacturing a disc-shaped recording medium.