DE3420595A1 - RECORDING CARRIER FOR HIGH DENSITY INFORMATION, MADE FROM CONDUCTIVE VINYL CHLORIDE RESIN CONTAINING RESIN FREE OF RESIN - Google Patents

Description

- ff ^ K & m ^m * "

The invention relates to the field of recording, and more particularly High information density recording media of the variable electrostatic capacity type such as Video discs or records on which the signal information is in the form of geometric patterns or changes is recorded.

In certain information reproduction systems from the electrostatic Capacitance type is the signal information in the form of geometric patterns or changes in a spiral Plane or recess or in concentric planes or recesses by compression molding a conductive resin composition made between dies, which have modulated ridges on their surface, creating a disc with an imprint of the matrices is obtained herein as signal information.

The individual geometric changes or patterns of the Disc are very small and they are arranged with a very high density. If the geometric patterns with a Pick-up needle / or a diamond carrying an electrode thereon, changes in capacitance between generated by the needle and the disc as a function of the geometric pattern or the geometric changes and with it the playback pictures and sounds. A video disk system is typical of such a playback system electrostatic capacitance type. The video disk system is currently being put into practical use.

In video disc systems, it is very important that the disc be of high quality. The disc should be good Characteristics or properties related to the signal-to-noise ratio, a good reproduction level of the signal, Durability with repeated reproductive cycles,

mechanical strength, heat stability, moisture resistance and the like. Such good properties of the disc are retained for long periods of time. To meet these requirements In order to meet, various conductive resin compositions for discs and various molding operations have heretofore been proposed. It is currently generally accepted that vinyl chloride resins, large surface area carbon black and, if necessary, stabilizers, Resin compositions containing lubricants and the like are most preferred from the practical point of view. the Molding procedures for the production of video discs or records from these resin compositions have been developed.

As already described above, the signal information in the disc is in the form of fine geometric patterns with a very high density imprinted. For example, 50 billion signal pits become each 0.3 to 0.4 µm in depth with a track pitch 1.35um embossed. The wells are concentric or spirally arranged in a disc surface with the innermost track having a diameter of 9 cm and the furthest outward trace have a diameter of 25 cm. Have adjacent wells Gaps of about 0.6 µm on the innermost track and about 1.7 µm on the outermost track Orbital track. Hence the geometric patterns or Changes very fine. In addition, a track signal is still in shape at the boundary line between adjacent tracks encoded by pits with a width of 0.6 to 0.7 µm and a depth of 0.05 µm.

To sample such fine signals, a diamond needle with an electrode is sliding with the concentric or spiral arranged signal pits contacted, while with the track signal according to the suggestion of the applicant (Victor Company of Japan, Limited), or sliding contact is made with a spiral recess.

in which the signal information is imprinted in the ground thereof, as suggested by RCA Co., Ltd., USA will. The geometric patterns or changes in the pits are sensed as changes in capacitance and reproduced as pictures or as sounds. For an accurate reproduction it is essential that the signals correspond exactly the modulated ridges of the dies. If the signals are not exactly molded into the disc high quality images or sounds cannot be obtained. This continues the commercial value of the Disks down. In particular, if the formation of the signals is very poor, the signal-to-noise ratio can decrease Signals interfere and signals from neighboring signal depressions can overlap. In extreme cases, the track signal become unclear or the shape of the guide groove cannot be maintained, so that correct scanning cannot be achieved.

In order to overcome these drawbacks, the formation of fine pit signals has been made from various angles including the selection of raw materials such as vinyl chloride resins, of stabilizers, lubricants and the like, kneading conditions, molding conditions and the like. It has been found that satisfactory video discs or digital records can be produced, when selected raw materials and optimal kneading and molding conditions are selected. In the industrial However, another problem of form errors of the signal occurs mainly as a result of the pollution of the production Matrices on their surfaces. In particular, if the compression molding process is repeated many times, the Matrices are contaminated and have accumulated debris on their surfaces, reducing the signal to noise ratio is deteriorated and interspersions or superimpositions occur.

It is known per se in the art that video or compact discs are made as follows: a Molten conductive resin composition is introduced or injected between the dies, with the dies being modulated Have burrs on their surfaces, and then molding and then cooling is used to produce the Disc carried out. The melt is from the central portion towards the peripheral portion of the dies entered, compression molded and cooled to obtain a thin slice.

The matrices are made by electroforming nickel from Mother molds made. Since the production is controlled so that the fine burrs, which the desired Corresponding to the signal, precisely forming it, the panes produced under good molding conditions then carry exact ones Well signals when the matrices are new. However, it has been found that with repeated use of a pair of dies (Female and male mold) over a long period of time the signal-to-noise ratio of the discs obtained deteriorates. The signal-to-noise ratio deterioration begins in the central portion of the disc and then extends on the circumferential section. This problem can easily be overcome if the dies are replaced with new ones. However, frequent changes are disadvantageous, since the manufacturing costs of the disks increase, especially not only expensive ones Matrices are consumed, but also time is required for changing. Also, starting materials also needed, since quantities thereof are required to make the change on the molding machine under optimal conditions to adjust.

Another serious problem with recording media

high information density is the on the recording medium or. blow

surface-generated flaking / attributable. It is well known that during playback of recorded signal

information the relative speed between the needle and the recording medium reaches values as high as 10 m / sec. If the recording medium has flakes or bubbles on it, the needle jumps from the recording medium surface in one with flaking or bubble-covered section, so that the signal information cannot be read exactly in this section, resulting in a defect or loss of an image to be reproduced. Furthermore, the jumped off needle can be a Scratch off part of the body of the recording medium when it comes into contact with the recording medium surface after it has jumped off and in this way the signal contained in the scraped part is lost, so that the dropouts increase and generated dust, which is unfavorable to the recording medium, is increased to an increased extent.

In general, bubbles or flakes will also appear through a number of causes as in the base thermoplastic resins, conductive base materials, or others Impurities contained in additives, foreign materials carried in during mixing or molding of the conductive resin composition and the heat decomposition products of the thermoplastic resin. These sources can be more appropriate Way through improvements in the preparation of the starting materials and through development of suitable ones Kneading systems and molding systems are reduced or switched off. With these improvements it is possible that immediately recording media obtained after manufacture show little or no flaking or blisters, so that no dropouts or dropouts are generated during playback.

However, it has been found that if such recording media are left standing the number of dropouts or failures increased as a function of time. Furthermore was

found that the increase in dropouts or dropouts was attributable to the fact that the recording media after it has been shaped and left to stand, the humidity falls below it

Formation of fine bubbles absorbed on its surface.

The object of the present invention is to provide recording media of high information density, which do not have the disadvantages outlined above, in particular the production of such high-quality recording media Information density from conductive resin compounds, during the production of which the matrices for longer periods of time than when using known, conductive resin compositions can be used and still higher recording media Quality and thus can be maintained at low production costs, furthermore the production of such recording media, which are stable and free from fine bubbles, even if longer periods of time elapse and they are under Conditions of relatively high humidity.

The high information density recording medium of the electrostatic capacitance type, the comprises a recording medium on which the signal information is recorded in the form of geometric patterns and that of a conductive resin composition which is a vinyl chloride resin and a conductive powder dispersed in the resin is prepared, the one of the present invention Record carrier is characterized in that the to vinyl chloride resin used in its manufacture by suspension polymerization of at least one starting monomer in an aqueous solution of at least one dispersant has been prepared for the suspension polymerization, and that the polymer slurry obtained up to the practical removal of the dispersant from the polymers has been washed. Sodium polyacrylates are preferably used as dispersants.

The invention is explained in more detail with reference to the drawing; in the drawing are:

Figs. 1 and 2 are graphs showing the relationship between the Y signal-to-noise ratio and the Number of disc molding cycles for each different one Resin compositions;

Figs. 3 (a) and 3 (b) are illustrations showing the relationships

between the number of video discs and the number of dropouts for the example 6 produced video discs immediately after their production or 12Oh after the Reproduce compression molding;

4 (a) and 4 (b) representations as in FIGS. 3 (a) and 3 (b),

however, for video disks of Comparative Experiment C, namely immediately after their manufacture or 120 hours after compression molding; and

5 (a) and 5 (b) representations as in FIGS. 3 (a) and 3 (B),

for the video discs of Comparative Experiment D, namely immediately after their production or 120 hours after compression molding.

The invention is illustrated below with the aid of preferred embodiments explained in more detail:

As described above, the invention is characterized in that a resin component for recording media of high information density is used from vinyl chloride resins, which was obtained by suspension polymerization and from which the / the dispersants absolutely necessary for the suspension polymerization to a substantial extent by washing removed.

As is known per se, for the production of recording media vinyl chloride resins used in high information density are obtained by suspension polymerization. In suspension polymerization becomes a starting monomer or several starting monomers as droplets together with a polymerization initiator dispersed in an aqueous solution of a high molecular weight dispersant for suspension polymerization. The monomer or monomers are polymerized with vigorous stirring or agitation of the reaction system.

It has been found that when forming record carriers with high information density from in the above-described In the manner of polymers, the matrices of the molding machine gradually obtained on their surfaces with unknown, from the polymer originating substances have been contaminated. The contamination of the matrices and the occurrence of dropouts in Time dependencies were confirmed as follows. Three kinds of vinyl chloride resins were obtained using the usual ones ingredients required for suspension polymerization. For this purpose, a vinyl chloride homopolymer, a vinyl chloride / ethylene copolymer with an ethylene content of 2% and an ethylene / vinyl acetate / grafted vinyl chloride copolymer, each with a degree of polymerization of 450. Each polymer was pelletized and subjected to repetitive forming of video disks to determine contamination of the matrices. Were further the discs obtained in terms of the number of dropouts immediately after manufacture and 120 h after Shapes studied. As a result, it was found that the vinyl chloride homopolymer showed less impact on contamination than the two copolymers. This was based on the dropout confirmed. Furthermore, it was found that the contamination and the number of dropouts do not depend on the Type of resin, but that it depends on the amount of

polymerisation used dispersant was because the production of the vinyl chloride homopolymer required much smaller amounts of the dispersant than in the case required for the preparation of the other copolymers.

In the case of vinyl chloride resins having a polymerization degree as low as 350 to 500, the vinyl chloride monomers usually become polymerized at temperatures as high as about 60 ° C to 80 ° C. If the polymerization occurs at these specified, carried out at high temperatures, a relatively large amount of dispersant is used for suspension polymerization required to make a vinyl chloride resin product that is capable of uniform mixing with a conductive Powder such as carbon black has a suitable size distribution.

A number of dispersants are commonly used either individually or in combination for suspension polymerization of vinyl chloride monomers and / or monomers copolymerizable therewith. Generally either individually or in combination water-soluble, partially saponified polyvinyl acetates, cellulose derivatives, Copolymers of vinyl chloride and maleic anhydride, polyvinyl pyrrolidone, sodium polyacrylates and the like are used. A large number of partially saponified polyvinyl acetates with different molecular weights, different Degrees of saponification and combinations with third components are known. Likewise, a large number of cellulose derivatives, which are used for these purposes and have different molecular weights and different Have substituents, known. These water-soluble dispersants are appropriately used depending on the desired type of vinyl chloride resin used. Of course Oil-soluble polymeric compounds can also be used in combination, provided that they are in dissolve the monomers used.

3A20595

Generally, vinyl chloride resins are used as the starting material for video discs or compact discs, by polymerizing at such high temperatures such as 60 C to 80 C, as described above, prepared. As a result, the vinyl chloride resin particles obtained have a low porosity with relatively poor gel properties and that removal of unreacted monomer becomes difficult. To avoid this, be preferred partially saponified polyvinyl acetates with degrees of saponification of 60 to 80% and a low molecular weight and cellulose derivatives such as hydroxypropyl cellulose or hydroxypropylmethyl cellulose used with a heat gelation temperature above 70 ° C. These dispersants are does not deteriorate in dispersibility even when used at high temperatures and have the effect of increasing porosity. Sodium polyacrylates are particularly preferably used because they are a have much greater dispersibility and for the production of polyvinyl chloride resins with a small size distribution are capable even when used in much smaller amounts than the other dispersants will. However, when sodium polyacrylates are used alone, the porosity of the resin particles obtained becomes higher relatively small, so that it becomes difficult to properly remove unreacted monomer from the particles to remove. The use of sodium polyacrylates gives vinyl chloride resins which are used as the starting material for video discs or compact discs are suitable, but it is not particularly advantageous from the standpoint of resin production. To avoid this, sodium polyacrylates are used in combination with other water-soluble, polymeric compounds such as partially saponified polyvinyl acetates, cellulose derivatives and the like.

The dispersants used for suspension polymerization can, depending on the type of vinyl chloride resin,

the stirring conditions of the reactor, the degree of polymerisation of a dispersant used and the like. Vary more or less strongly. The amounts are usually in the range of from 0.02 to 0.8 percent by weight of the vinyl chloride monomer in the case of vinyl chloride homopolymer and from 0.05 to 2.0% by weight for the total amount of monomers in the case of copolymers.

As previously described, sodium polyacrylates have one much higher dispersibility than other dispersants. The degree of polymerization is the same for suspension polymerization of the polyacrylates advantageously in the range from 5000 to 100,000. There are the following reasons for this: In the manufacture of vinyl chloride resins, it is common for dispersants to be dissolved in water and filtered, to remove foreign materials from it. This filtration process is performed when using sodium polyacrylates, their The degree of polymerization exceeds 100,000 is difficult because an aqueous solution thereof has too high a viscosity. on the other hand are sodium polyacrylates with a degree of polymerization below 5000 for use in suspension polymerization not particularly suitable because they hardly develop any emulsifying effect. ~ "

The amount of sodium polyacrylate having a degree of polymerization of, for example, 50,000 ranges from 0.005 to 0.05% by weight on a basis on the monomer for vinyl chloride homopolymer, and from 0.01 to 0.1% by weight, based on the total amount Monomers for copolymers.

If sodium polyacrylates are used in combination with other types of dispersants, the other should be Dispersants contribute about 30 to 70% of the desired suspending and dispersing capacity. The dispersing capacity for sodium polyacrylates is 7 times to 15 times as large as the highest capacity of partially saponified poly-

vinyl acetates or cellulose derivatives. Therefore, when sodium polyacrylates are used together with partially saponified polyvinyl acetates or cellulose derivatives, sodium polyacrylates are used in amounts in the range from 0.002 to 0.04% by weight and the polyvinyl acetates or cellulose derivatives in amounts in the range from 0.01 to 0.2% by weight. , both based on monomer _f for vinyl chloride homopolymer. The amounts are in the range from 0.003 to 0.007% by weight of sodium polyacrylates and from 0.01 to 0.2% by weight of polyvinyl acetates or cellulose derivatives, both based on the total amount of monomers for copolymers.

Vinyl chloride resins used in the present invention should have a degree of polymerization of 350 to, and they include, for example, vinyl chloride homopolymers, Copolymers of vinyl chloride with vinyl acetate, ethylene, propylene, alpha-olefins such as 1-octene, 1-hexene and the like, acrylate monomers such as ethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, Methyl acrylate and the like, as well as ethylene / vinyl acetate copolymers which are grafted with vinyl chloride, and the like. If copolymers are used, the comonomers content should preferably be below 25% by weight.

In practicing the invention, these will be vinyl chloride monomers and / or the other copolymerizable monomers are suspension-polymerized in the usual manner, then should the reactor and the stirrer are preferably washed with water to remove foreign materials therefrom. In Similarly, monomers, dispersants and other additives, if necessary after dissolving in water, should preferably be filtered to remove foreign matter of a certain size therefrom. The obtained resin particles are washed sufficiently with water to remove the water-soluble dispersants used therefrom. This can cause contamination of matrices with repeated use and the appearance of fine bubbles

avoided on the disc surface in a suitable manner will.

Preferably, after the completion of the suspension polymerization, the polymer slurry is washed with water by conventional procedures including filtration and / or dehydration in a centrifuge and / or by settling, and water is added to the resulting cake to form a slurry. This procedure is repeated several times. The completion of the washing process can be determined in a simple manner by analyzing a component in the used water or washing water, for example sodium ions in the case of sodium polyacrylates. In general, the washing is continued until the water-soluble dispersants are removed to a level below 400 ppm, and preferably below 200 ppm in the washing liquid (ppm = parts per million) in order to obtain video discs or digital recording discs which are free of fine bubbles and in the manufacture of which the problem of contamination of the matrices is avoided. The value below 200 ppm can be achieved if the resin particles are washed according to the procedure described above using 5 to 20 times the total volume of water. For washing, the resin particles should preferably be washed twice or more times the volume of water, since too little washing water is less effective. The washing process including filtration and / or dewatering or the like is advantageously repeated several times. If complete washout is not achieved, a used water-soluble dispersant may be deposited on the die surfaces when such a resin is compression molded, thereby contaminating the dies. The water used for the washing process should preferably have a temperature of 10 to
Ensure washing out.

have a temperature of 10 to 50 ° C to be effective

Even if water-insoluble, but monomer-soluble dispersants such as ethyl cellulose or low molecular weight surfactants such as polyethylene glycol can be used in combination with water-soluble dispersants, the removal of the dispersants, and both the water-soluble and the water-insoluble are achieved in the same way as described above will.

As described above, the dispersants for suspension polymerization are by adding water to a Polymer slurry or a wet polymer product removed. Vinyl chloride resins that have been dried once, when washed with water, cannot be washed out satisfactorily because the particle surfaces of the dried resin do not wet each other. Furthermore, there would be the additional step of drying the resin particles nor increase the possibility of inconvenient incorporation of foreign materials therein and the energy costs for drying would have to be applied. Therefore, after the completion of the Polymerization however washed out before drying.

For the washing process, clean water, in particular clean water treated with an ion exchanger, is advantageously used used from which foreign materials have been removed. In practice, the polymer slurry is first in a Treated drainage device to produce a cake, fresh water is used to form a cake on this cake Slurry added, then the procedure described above is repeated until the amount of dispersant reaches a value of no more than about 400 ppm in waste or dirty water. Alternatively, the slurry be left in a tank to allow the resin particles to settle. After removing the supernatant liquid water is added to the particles to make a new slurry, then this type of slurry is

repeatedly until the same amount of dispersant, as previously mentioned, has been achieved.

For the production of recording media with high information density according to the invention, the vinyl chloride resins thus obtained become fine with a conductive powder such as carbon black Metal powders or the like. In an amount of 5 to 30 wt .-%, based on the resin, mixed, whereby a conductive Resin mass is obtained. The mass can also contain additives usually used for these purposes, e.g. lubricants, heat stabilizers and the like.

The mixing, kneading, pelletizing and compression molding of the mass can be carried out according to any known in the art Techniques are carried out so that they are no longer explained here.

The invention is explained in more detail below with reference to production examples, examples and comparative experiments .

Production example 1

Manufacture of vinyl chloride resins according to the invention were used:

Vinyl chloride was with or without copolymerizable monomers in a 600 l autoclave equipped with jacket and stirrer was polymerized. Corrosion (rust) deposited on the inner surfaces of the autoclave was revealed with a scratch removed and carefully sealed. Methylene chloride was charged into the autoclave and then heated to 40 ° C., then was stirred for 1 h. The methylene chloride was then stripped off and pressurized water with an excess pressure of 59 bar is injected into the autoclave in order to completely remove crusts from it. Purified by means of ion exchangers Water, which is filtered through a filter with openings of 0.5 µm was filled into the autoclave for washing.

Purified by means of ion exchangers for polymerization used water was filtered through the same type of filter as used before. Vinyl chloride monomer and copolymerizable monomers were each filtered through a filter with openings of 1 µm. A suspension stabilizer For the polymerization, the water purified by means of an ion exchanger was used to produce a 2% strength by weight aqueous Solution dissolved, then filtered through a filter with openings of 1 µm.

A polymerization initiator, as it was, sent through.

The polymerization reaction was carried out as follows: The water purified by means of an ion exchanger was poured into the washed autoclave; charged the predetermined amounts of suspension stabilizer and polymerization initiator with filtration. Thereafter the autoclave was closed, then the air in the system was evacuated to a pressure of 46.6 mbar (35 mmHg), then the vinyl chloride monomer was charged with stirring. The system was brought to a polymerization temperature at which the exothermic polymerization reaction begins, heated. Thereafter, the system was based on that shown in Table 1 Maintained the temperature at which the reaction was allowed to proceed. After the degree of polymerization is about When it reached 70%, the temperature inside was lowered to 65 ° C, and the remaining vinyl chloride monomer became regained. The internal pressure was reduced to 0 bar overpressure, then 2 m / h of nitrogen gas were passed from the bottom of the autoclave for 2 h while passing through a filter introduced with openings of 0.5 µm and withdrawn from the upper part of the autoclave to remove the remaining vinyl chloride monomer from the system. The internal pressure was then increased to 0.98 bar overpressure using pressurized nitrogen gas increased.

3420535

The obtained vinyl chloride polymer slurry was through a metal sieve with a mesh size of 0.35 mm with the aid of the pressurized nitrogen in the autoclave transferred into a 1000 1 container, this container with filtered, cleaned by means of an ion exchanger Water and had a dispensing nozzle and stirrer.

Part of the slurry was dewatered in a centrifuge, which was in a room with cleaner, through a HEPA filter was conducted air under positive pressure, whereby a cake was obtained. To this cake, water was added in an amount 3 times the amount of the cake to be formed added to a slurry. The slurry was stirred for 1 hour, then the procedure described above was followed repeated twice more. The cake obtained in the fourth dehydration was placed in a conical dryer dried so that dust could not enter, whereby fine particles of vinyl chloride resin were obtained. The polymerization conditions and the compositions of the vinyl chloride resins prepared in the same manner as described above are compiled in the following table 1.

Table 1

Attempt no.

composition

Vinyl chloride polymer

Vinyl chloride-vinyl chloride / hanopolymeric ethylene copolymer

Ion exchange
purified water (kg) 290 290 290 Vinyl chloride monoirveres (kg) 230 200 190 Ethylene (kg) - - 10 Polymerization initiator
(Note 1) (g) 160 160 180 Partially saponified poly
vinyl acetate
(Note 2) (g) 600 1100 Hydroxypropylmethyl
cellulose
(Note 3) (g) - 800 - Polymerization
temperature (C) 80 80 77 Polymerisation time (h) 8.5 8.5 9.0 Polymerization cjrad 480 480 490

2.3

Canonane content in the final product (%)

Size distribution

<0.35 mm (%)

<0.152 mm (%)

<0.076 mm (%)

Bulk density

Note 1: Commercial polymerization initiator (trade name Kaya

ester 0 by Kayaku Noury Co., Ltd.) Note 2: Partially saponified polyvinyl acetate (trade name Gosenol

KH-17 from The Nippon Synthetic Chem. Ind. Co., Ltd.) Note 3: Hydroxypropylmethyl cellulose (commercial product Metollose 90SH100 from Shinetsu Chem. Co., Ltd.)

99 99 99 67 58 85 3 5 18th 0.55 0.53 0.48

Comparative manufacturing test A

For comparison, vinyl chloride homopolymers were produced, the general procedure of experiments 1 and 3 of preparation example 1 being repeated with the exception that part of the slurry withdrawn from the reactor is dewatered in the centrifuge and without washing with water was dried in a conical dryer to obtain fine particles of vinyl chloride resins, Runs Nos. 4 and 5 became.

Production example 2

The general procedure of Preparation 1 was repeated except that 0.1 wt% sodium polyacrylate was used and 2% by weight of another one dissolved in ion-exchanged purified and filtered water Dispersants were used and a resin slurry was produced. The slurry was then dewatered and ion-exchange purified water in an amount 3 times the volume of the produced vinyl chloride resin washed, then stirred for 1 h. This procedure was repeated twice more. The content of sodium polyacrylate in the water used was analyzed and found to be less than 12 ppm. The one at the final The cake obtained from dehydration was dried, taking care not to get dust into the resin particles. The sodium polyacrylate content in the resin was determined to be about 6 ppm.

In this way, four vinyl chloride resins in total were produced. The manufacturing conditions and compositions as well as the resin properties are shown in Table 2 below compiled.

(kg) - 24 - 7th 34205-95 8th 9 (kg) Table 2 Vinyl-
chloride-
homopoly
meres vinyl
chloride/
Ethylene
copoly-
meres vinyl
chloride/
Ethylene
copoly-
meres Attempt no. (kg) 6th 290 290 290 composition (G) Vinyl-
chloride-
homopoly
meres 200 190 190 Ion exchanger
purified water (G) 290 - 10 10 Vinyl chloride mono-
meres (G) 200 160 180 180 Ethylene (G) - 600 500 Polymerization
initiator (note 4) <° C) 160 500 _ - - Partially saponified
Polyvinyl acetate
(Note 5) (H) 300 60 80 100 Hydroxyprqpylmethyl-
cellulose (note 6) _ 80 77 77 Sodium polyacrylate
(Note 7) 40 ■ 8.5 9/0 9.0 Polymerization
temperature 80 480 490 490 Polymerization time 8.5 Degree of polymerization 480

Comonomer content
in the end product (%)

Size distribution

<ο, 35 mm (%)

<o, 152 mm (%)

<0.076 mm (%)

2.3

Bulk density

99 99 99 67 58 85 3 5 18th 0.55 0.53 0.48

99 75 18

Note 4: Polymerization initiator (trade name Kaya ester 0 from

Kayaku Noury Co., Ltd.)
Note 5: Partially saponified polyvinyl acetate (tradename Gosenol KH-17 by The Nippon Synthetic Chem. Ind. Co., Ltd.)

Note 6: Hydroxypropylitiethyl cellulose (trade name Metollose 9OSH1OO by Shinetsu Chem. Co., Ltd.)

Note 7: Nafcrium polyacrylate (trade name Aron A-20P by Toa Synthetic Chem. Ind. Co., Ltd.)

Comparative manufacturing test B

In this comparative experiment, vinyl chloride resins were used repeatedly prepared according to the general procedure of Run No. 3 with the exception that a portion of the withdrawn from the reactor Slurry was dewatered in the centrifuge and dried in the conical dryer without washing with water, whereby fine particles of vinyl chloride resin (Experiment No. 10) were obtained. Furthermore, the mode of operation of the experiment No. 8 repeated with the exception that no sodium polyacrylate, but 1100 g of partially saponified polyvinyl acetate was used to obtain a vinyl chloride resin (Experiment No. 11).

Examples 1 to 3

100 parts by weight of each of the resins obtained in Experiment Nos. 1 to 3, in which those used for suspension polymerization Dispersant had practically been removed by washing with water, 5 parts by weight of dibutyltin mercaptoester as a stabilizer (trade name STANN JF-9 5 by Sankyo Organic Chemicals Co., Ltd.), 2.0 parts by weight of a fatty acid glycerol ester as a lubricant (trade name RES-210 by Riken Vitamin Co., Ltd.), 0.5 part by weight of a fatty acid alkyl ester (Trade name RES-310 by Kao Soap Co., Ltd.) And 1.0 part by weight of dimethylpolysiloxane (trade name RES-421 from Sinetsu Chem. Co., Ltd.) were mixed in a 20 l Henschel mixer up to a temperature of 110 ° C., then the mixer was operated at a low speed so that the temperature was lowered to 70 ° C. To the mixture, 20 parts by weight of conductive carbon black (trade name CSC-150A by Cabot Co., Ltd., USA) was added, then was again heated to 110 ° C. and kneading was continued at high speed for 15 min.

Thereafter, the mixture was cooled to room temperature.

The mixture was pelletized by means of a kneader (PR-46 from Buss Co., Ltd., Switzerland). The pellets obtained were treated in a metal separator to remove metals or metal-containing pellets from the pellets and pressed on a video disc press for making video discs.

Comparative experiments A and B

The general procedure of Examples 1 to 3 was repeated with those obtained in Runs Nos. 4 and 5 Resins were used and video disks were made.

In the aforementioned examples and comparative tests, each conductive resin composition became about 300 video disks in a continuous manner using matrices on which reference signals are recorded for signal measurements were molded.

The video disks obtained in these examples and comparative tests were each measured to the recorded thereon Signals to determine the degree of Y signal-to-noise ratio deterioration. The results are shown in Figs.

As can be seen from these figures, there is little contamination of the matrices when the vinyl chloride resins are used are practically free of suspension dispersants. Therefore, the video disks according to the invention only have very few signal defects and good reproduction properties. On the other hand, it can be seen from Fig. 2 that when used of vinyl chloride resins from which the dispersants have not been removed by washing but are still present, that the result is contamination of the dies with repeated compression molding. Compression molding with the contaminating

th matrices leads to video discs with signal errors and poor playback properties.

Examination of the dies through a scanning electron microscope after the completion of the 300 compression molding cycles revealed that on no foreign matter was deposited on the matrices.

Examples 4 to 7

The general procedure of Examples 1 to 3 was repeated, using 100 parts by weight of the vinyl chloride resins of Experiment Nos. 6 to 9, and became video disks manufactured.

Comparative experiments C and D

The general procedure of Examples 1 to 3 was repeated, using 100 parts by weight of the vinyl chloride resins of Experiments 10 and 11, and became video disks manufactured.

In Examples 4 to 7 and Comparative Experiments C and D. discs were compression-molded from each mixture using matrices on which reference signals were used for signal measurement were recorded. Immediately after the press molding and 120 hours after the press molding, each of the video disks was in a Dropouts counting device (failures) examined to determine the number of dropouts in terms of which good image quality occurred.

The video disks obtained in Examples 4 to 7 showed no dropouts, while some of those produced in the comparison Video disks resulted in dropout noise, i.e. the video ' Slices of Comparative Experiment C gave an average of 0.75 Dropouts, and the video disks of Comparative Experiment D gave an average of 1.9 dropouts. From this it can be seen that the video disks or recording media according to the invention, which showed no dropouts, determined as NG, were marked.

The video disks of these examples and comparative experiments were further tested at a temperature of 40 C and a relative humidity of 90% for 96 hours and then under normal temperature and normal humidity conditions kept for 24 hours. Each slice was then counted for dropouts. As a result, it was found that the disks or recording media according to the invention showed no reduction in image quality, even when preserved under these harsh conditions, the comparative disks are considerably inferior Properties showed.

The results are shown in Figures 3 (a) and 3 (b) through 5 (a) and 5 (b), the results of which are the same as immediately after Molded disks are shown in Figures 3 (a), 4 (a) and 5 (a), while the results of the disks 120 hours after compression molding are shown in respective Fig. (B). It should be noted that the Examples 4 to 7 of video disks produced in accordance with the invention are comparable in terms of dropout characteristics with the results of the discs of Example 4 being representatively shown in Figures 3 (a) and 3 (b).

Claims (13)

Claims fi.) Recording medium for high density information of the electrostatic Type of capacitance which comprises a recording sheet on which the signal information is in the form geometric pattern is recorded and which consists of a conductive, a vinyl chloride resin and a conductive A resin composition comprising powder, characterized in that the vinyl chloride resin by suspension polymerization of at least one monomer in an aqueous solution of at least one dispersant and washing the resulting Harζaufschlämung until the dispersant is conveniently removed from the finished resin product. 2. High information density recording medium according to claim 1, characterized in that the vinyl chloride resin has a degree of polymerization of 350 to 600 and is vinyl chloride homopolymer. 3. High information density recording medium according to Claim 1, characterized in that the vinyl chloride resin a copolymer of vinyl chloride and vinyl acetate, ethylene, propylene, an alpha-olefin, or an acrylate monomer is. 4. Recording medium high 'information density according to claim 1, characterized in that the vinyl chloride resin is a copolymer of ethylene and vinyl acetate grafted with vinyl chloride. 5. High information density record carrier according to claim 1, characterized in that at least one of those used in the manufacture of the vinyl chloride resin Dispersant is a water soluble polymer. 6. High information density recording medium according to claim 5, characterized in that the during manufacture of the vinyl chloride resin used, water-soluble polymers made of partially saponified polyvinyl acetates with a Degree of saponification from 60 to 80%, cellulose derivatives or mixtures thereof is selected and in an amount of 0.002 to 0.8% by weight, based on at least one monomer, when this monomer is vinyl chloride monomer has been used. 7. High information density record carrier according to Claim 6, characterized in that in the preparation of the vinyl chloride resin, the water-soluble polymer in an amount of 0.05 to 2.0 wt .-%, based on the mono- kidneys, the monomers being a mixture of vinyl chloride monomers and a monomer copolymerizable therewith, has been used. 8. A high information density record carrier according to claim 5, characterized in that the water-soluble dispersant is used in the manufacture of the vinyl chloride resin is a sodium polyacrylate material having a degree of polymerization in the range of 5,000 to 100,000 and in an amount in the range from 0.005 to 0.05% by weight, based on the monomer, when this monomer is vinyl chloride monomer has been. 9. The high information density record carrier according to claim 8, characterized in that the sodium polyacrylate material is used in the manufacture of the vinyl chloride resin in an amount of 0.01 to 0.1% by weight, based on the monomers, the monomers being a mixture of vinyl chloride monomers and a monomer copolymerizable therewith has been used. 10. High information density recording medium according to claim 8 or 9, characterized in that the Preparation of the vinyl chloride resin Another type of water-soluble dispersant selected from the group consisting of partially saponified polyvinyl acetates, cellulose derivatives and mixtures thereof. 11. The high information density record carrier according to claim 1, characterized in that in the production of the vinyl chloride resin a water-insoluble dispersant, which is soluble in at least one monomer has been used. 12. A recording medium of high information density according to claim 1, characterized in that the one or more dispersants have been removed during the washing process to a value below 400 ppm. 13. The high information density record carrier according to claim 12, characterized / that the dispersant or agents are used in the production of the vinyl chloride resin a value below 200 ppm have been removed.