JPS59119554A - 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 current of inert gas of 550-850 deg.C containing water vapor and cooled. Then, this carbon black is washed with weak hydrochloric acid and water and dried. A conductive material is prepared by mixing the refined carbon black with thermoplastic resin. This is formed and worked, and a discoid recording medium that forms pits 3 corresponding to information signals vortically 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.-100pts.wt. of disk forming resin.

Description

[Detailed Description of the Invention] The second field of application of the invention is an electrostatic field! Guide to company-style video discs, etc.? 11
．． This invention relates to a method for producing a disc-shaped body using carbon black.

In the field of audio record industry, conventional examples (old generation and its problems)
For example, if you put a stamper with information signals on the surface.
Disc records are mainly manufactured by compression molding a copolymer of vinyl chloride and vinyl acetate.

Also, disk-shaped recording media using conductive TTTF+ materials, such as capacitive end-type 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, (2) is a hole provided in the center of this disk-shaped disk (1), and (3) is a bit corresponding to an information signal provided on the surface of the disk-shaped disk (1). be.

When such a conductive disk is placed on the rotation system of the player and rotated, and a needle with a pole is placed on the surface of the disk with a bit for each metal, information is statically transmitted according to the bits with grooves on the disk surface. 9F? , obtained as a change in capacitance.

Unlike conventional audio records, static
In the case of a tc+7 disc-shaped recording medium, the disc has enough no! '1. Having J3 in iij is a waste ↑
Therefore, Ic resin, [I (1) in 1]
Hair's conductive carbon black must be mixed in, but this does not affect the manufacturing process of the disc or the physical or destructive characteristics of the disc.
It is Cζ that causes various interludes in c.

(For example, if there are many impurities contained in carbon black, these impurities will cause various defects such as protrusions on the surface of the disk, [1]
Interfering with the production or stamping (Iiii)
do. Zunawaji, pigeons containing these same rows of 4 objects of the disc; minute tC+. These bulges cause the needle to jump or cause poor tracking when played by Breyer. If you hit the needle in the history and hit the 7, attach the disc ■1 to the middle 3 after it falls onto the disc surface.

Considering these 11 points, it is classified as a contact furnace black.
When the surface of a disk prepared by kneading carbon black and C10 fat was observed with an optical microscope needle, it was found that there were many white deposits with a diameter of more than ten microns. Furthermore, when this disc was played by a player, it was observed that needle scratches were carved at the white precipitate, and needle scratches were again carved at a distance of several hundred microns from there toward the rear. . These scratches grew as the film was washed over the river, and at the same time the quality of the playback image deteriorated.

According to analysis using the X-Kizuna Micro Analyzer, these white precipitates were found to contain calcium (CFI) and sulfur (Sl). The main component of the ash obtained during this process was determined to be calcium sulfate (Ca So
It became clear that it was the anhydrous salt of b). Although it is extremely difficult to analyze the form in which calcium (Ca) and sulfur (S) exist in carbon black,
Calcium sulfide (CaS) and calcium thiosulfate (C8,520) contain calcium and sulfur.
3) and calcium sulfate (CaSO4) and its hydrated salts. It is also considered that sulfur is combined with free sulfur and carbon.

By the way, when carbon black is heated in a persimmon atmosphere, it releases sulfur dioxide gas (502) and hydrogen sulfide (CH25).

It has become clear that various sulfur compounds are generated in the form of carbon disulfide (C52), carbon oxysulfide (CO5), etc. 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 raw material petroleum and the cooling water used during the manufacturing process, and carbon black manufacturers are also making efforts to reduce the impurity barrier, but manufacturing By pre-stabilizing the conductive carbon black, which is difficult to remove sufficiently due to cost considerations, it is possible to achieve excellent reliability without A < fL due to impurities on the surface. The purpose of this invention is to manufacture disc-shaped recording media.

In order to achieve the above object, the method for manufacturing a disk-shaped recording medium of the present invention includes heat-treating conductive carbon black in an inert gas stream containing water vapor at a temperature of 550'C' to 850°C. The carbon black is washed with weak hydrochloric acid and water and then dried, and the first purified carbon black obtained by drying is kneaded with a thermoplastic resin to produce a conductive material. This conductive material is then molded to produce a disk recording medium in which pits corresponding to information signals are formed spirally or concentrically at a predetermined spacing. As a result, it is possible to manufacture a disk-shaped recording medium with excellent reproduction characteristics and free from blisters caused by impurities on the surface.

DESCRIPTION OF EMBODIMENTS The structure of the method of the present invention will be explained below based on actual examples. The shape of the disk-shaped recording medium produced by the method of the present invention is the same as that shown in FIGS. 1 to 8 above.

First, examples of thermoplastic resins that can be used in the present 1996 method include hinyl chloride, vinyl chloride/vinyl acetate coelectrolyte, and J-vinyl vinylide/ethylene copolymer.

MA vinyl chloride/propylene copolymer, vinyl chloride/(
meth) Acrylic acid alkyl ester copolymer *Axolonitrile/styrene copolymer, acrylonitrile/lyl/styrene/butadiene copolymer + y Acrylonitrile/
Examples include styrene/ethylene copolymer, methyl methacrylate, and methyl methacrylate/butadiene copolymer. In addition, along with the heat rjj plastic resin of these jL et al., a heat stabilizer is used as needed.

It goes without saying that plasticizers and side lubricants are used.

Regarding the addition rate of carbon black to the resin used in the method of the present invention, the tooth width from the disk is 5
7111L must be added to the extent that it imparts sufficient #electrification so that the capacitive reading is at the river level, part 1
-1 value is when the volume resistivity of the molded product is more than 10,000.
Preferably it is 100Ω·a or less. Is it suitable for adding these conditions? Addition of carbon black as likelihood-imitating particles h1. is disk constituent resin 10
0 cars! '+j 1 part by weight is 10 to 40 parts by weight, preferably 1 part by weight to 15 to 35η. If the addition of carbon black (7+1) is less than 15 parts, particularly less than 1 part of 10H, the conductivity and properties of the disc cannot be sufficiently improved. On the other hand, if the amount added exceeds 35 parts by weight, especially 40 parts by weight or more, the processability of the kneaded product decreases and the brittleness of the finished disk increases, making it unsuitable for practical use.

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

(Example 1) Particle size 20 ml (electronic microscopic method), surface area (nitrogen adsorption method) 1580 rrt/y, oil absorption (DBP)
880 ll (/100 f.

PH8.5, ash content 0.98! i! Conductive carbon black (Ca IJ) No. 5 was put into an alumina boat, first put into the core tube of a tube furnace, and heat-treated in a gas flow of a mixed gas of nitrogen, carbon dioxide, and water vapor fed from one end of the tube furnace. I did this. The temperature of carbon black in all cases was about 700°C. At this time, hydrogen sulfide (H2S) was observed in the gas flowing out from the other end of the tube furnace. The generation of hydrogen sulfide was terminated by treatment for 2 hours, and 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. It was then dried to obtain purified carphone black. The ash content of carbon black after heat treatment and washing is approximately 0.06%.
Met. Furthermore, as a result of X-ray diffraction, the main component of the crystalline phase of the ash in the carbon black that had not been heat-treated was calcium sulfate (CRS(,)4), but the main component in the ash of the heat-treated carbon black was Calcium carbonate (
Ca, CO3). Furthermore, the PR of carbon black after heat treatment was 9.2.

Next, the above-mentioned treated carbon black...-20 parts vinyl chloride/lauryl acrylate copolymer (group Ii'i
Ratio 95:5, polymerization ji480) ... 100 parts stabilizer (three-shared machine (+9d '1!!, Stan JF-2
0u)...8 parts irf agent (f3 woodhen'y-
A mixture consisting of 2 parts (manufactured by Loxiol GE-2) was thoroughly mixed using a high-speed stirrer, and then melt kneading was performed using hot rolls. Manufactured.

(17 middle row) ] ) Using untreated carbon black ★b same as Example 1
Disc by law! 11! I built it and performed surface observations etc.

The disks immediately after compression molding obtained in Sister Example 1 and Comparative Example 1 were observed using an optical microscope and analyzed using an X-ray microanalyzer, and the disks that had been played several times on a player were also examined. Surface observation was performed. As a result, no large precipitates were found on the surface of the heat-treated carbon black-added disk, but on the surface of the untreated carbon black-added disk, a large number of white precipitates were found. Precipitates were detected. According to an X-ray microanalyzer, the main components of the white precipitate are sulfur (S) and calcium (C).
8), so this cell can be interpreted as Cn, 5Q4. This white precipitate catches the needle when playing on the player (by the way, the dropout 11 is 19L in distance from 1 horizontal scan 11!ψ).

On the disc of the comparative example, which was played several times using a player, needle scratches were observed on the white precipitate, and scratches due to needle skipping were observed behind the white precipitate. moreover,
It has been observed that the scratches caused by this needle skipping grow each time the disc is played, and eventually go around the disc and lead to the previous scratches.

(Actual example 2) Particle (4420mal (YiX, microscopic method), surface area (nitrogen IK method) 1850n?/
y, Iνshi tears 11ft, (DBP) 82
0 me/1oof, PH8.0, ash'+ 1.
52% ion-conducting carphone black ((Abot Small B) 2 onp was placed in a quartz boat and first placed in the core tube of a tube furnace, and humid nitrogen and carbon dioxide gas were injected from one end of the tube path. The heat treatment was carried out in a mixed gas flow.

At this time, 1g4 of carbon black was heated to approximately 800'C. At this time, the gas flowing out from the other end of the tube furnace was introduced into a washing bottle containing water, and a fixed cough of hydrogen sulfide (HhS) was performed. Next, after cooling the heat-treated carbon black,
Wash it by soaking it in dilute hydrochloric acid solution, then wash it with pure water for 8 to 4 hours.

Then, it was dried to obtain 1 Blue M carbon black.

The ash content of the carbon black after partial treatment and washing was about 0.09%. In addition, as a result of X-ray diffraction, the crystalline phase of the ash of carbon black that had not been heat-treated was found to have calcium sulfate (CaS04) as the main component and sodium chloride (NaC1) as a subcomponent, but carbon black that had not been heat-treated The main component of black ash was calcium carbonate (CaCOs), and the pH was 92.

Next, a disk was manufactured in the same manner as in Example 1 using the carbon black that had undergone the heat treatment and cleaning treatment.

(Comparative Example 2) A disk was manufactured in the same manner as in Example 1 without subjecting the raw material carbon black used in Example 2 to heat treatment.

(Comparative Example 8) The heat treatment method was almost the same as in Example 2, and the experiment was conducted by changing only the gas flowing into the furnace tube. That is, a disk is manufactured by mixing a small amount of air into the gas flowing from one end of a tube furnace and performing the same actual viscosity.

The surface of each disk obtained in Example 2 and Comparative Example 2.8 was observed and observed using an optical microscope. As a result, almost no particles were observed in the disk of Example 2, but the surface of each disk obtained in Comparative Example 2.8 was observed. On the disk, a white precipitate with a size of 101ten rlO was observed. Furthermore, when these discs were played on a player, skipping of needles due to deposits was observed.

Next, when each disk obtained in Actual Model Δn Example 2 and Comparative Example 2.8 was placed in a constant temperature and humidity chamber at 40°C and 95% RH and left for 72 hours, the surface of the disk in Example 2 was Although almost no blisters were observed, blisters of 80 to 50 μm due to moisture absorption were observed in the disk of Comparative Example 2.8.

(Comparative Example 4) The heat treatment method was almost the same as in Example 2, but an experiment was conducted by changing only the gas flowing into the furnace tube.

That is, after performing the same actual hQ using only nitrogen as the gas flowing from one end of the tube furnace, a disk was manufactured using carbon black that had been heat-treated and washed.

Regarding the disc manufactured in Example 4 of Comparison 119, precipitation of the same substance was also observed on the surface, which caused needle skipping during performance.

(Comparative Example 5) The heat treatment method was almost the same as in Example 2, but a disk was manufactured using carbon black without washing 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.

As explained while showing the above two examples and five comparative examples, when discs are manufactured using ordinary carbon black as a raw material containing compounds containing sulfur and calcium as impurities, solid precipitates are formed in these discs. This causes dropouts and disk deterioration, but since carbon black contains such impurities, it is considered difficult to prevent the precipitation of impurity solids on the disk surface. That is, in order to prevent the precipitation of impurity solids, it is desirable to remove impurities at the carbon stage. Therefore, in the method of the present invention, carbon is first heat-treated to transform impurities into a substance that is easily dissolved in acid and water, and then the carbon is washed.

The heat treatment temperature for conductive carbon black is 550°C.
~850°C is suitable. There was no shrine at 550℃ J.
This is because if the temperature exceeds 850°C, reduction of calcium sulfate (CaSO4) by carbon black is difficult to occur.

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

(]) It is possible to produce a disk-shaped recording medium with excellent playback characteristics and no blisters caused by impurities on the surface.

(2) Therefore, it is possible to prevent needle dropout and needle skipping, and to improve the reliability of the disc, fJJJ
It is possible to significantly improve the feeling of walking.

[Brief explanation of drawings]

The drawings show the shape of a disk-shaped recording medium, and FIG. 1 is a top view of a disk to which the method of the present invention is applied, FIG. 2 is a partially enlarged view of a part of the disk surface in FIG. 1, and FIG. FIG. 2 is a sectional view of FIG. 1; (1)... Disc-shaped disk, (2)... Center hole, (
3)...Bit diagram 2

Claims (1)

[Claims] 1. >qnr, strength - heat-treat carbon black in a stream of inert gas containing water vapor at 550°C to 850°C, then cool it, then wash this carbon black with weak hydrochloric acid and water, and then dry it, Next, the purified carbon black obtained by drying and the thermoplastic resin are kneaded to form 111. Generate a conductive material, then process this conductive material F) to form 1[・≧,
A method for manufacturing a disk-shaped recording medium, in which a 7'F recording medium is manufactured in which bits corresponding to an information signal are formed at predetermined intervals in an i-wound shape or a concentric solid shape.