DE3414053A1 - RECORD CARRIER FOR HIGH DENSITY INFORMATION - Google Patents

Description

Kl:,

. = ": - 34U053

The invention relates to playback systems due to variable electrostatic capacity and in particular recording media with high information density, such as video disks or digital records, on which signal information .. in the form geometric changes is recorded.

In certain information reproduction systems, the signal information is available as geometrical changes or in the form of Pits in a spiral track or groove or in concentric tracks or grooves on an information recording medium upset. The reproduction of the medium with the signal information is done in the following way: A stylus or a stylus, for example a diamond with an electrode attached, is moved relative to the recording track of the medium, and there are changes in capacitance traversed between the receiving needle and the medium as a result of geometric changes in the track or the groove.

Various types of information records are available. tion has been proposed in the reproduction system described using electrostatic capacitance. With such a Recording medium, an electrode is created on the surface of a recording substrate on which geometric Changes can be generated by pressing in accordance with the signal information. This causes the formation of an electrostatic Capacity between the electrode of the recording medium and the needle electrode allows. For example, the recording substrate with a thin metal film with a thickness of the order of 10 mm and one covering the metal film .dielectric layer with the same order of magnitude of thickness covered. The dielectric layer serves to provide a To prevent short-circuiting of the electrodes and to increase the dielectric constant in the space between the electrodes. When recording of the type described are a variety of manufacturing steps including the compression molding of the recording

EPO COPY ft

substrates, the deposition of the thin metal film and the dielectric layer and the like are required. In order to The manufacture proves to be complicated and troublesome and, in particular, because of the need for relatively large manufacturing facilities as expensive.

Another type well ter Inf ormationsaufzeichnung with use of electrostatic capacitance is obtained by press-molding a conductive plastic mass, which as contains a resin such as polyvinyl chloride with admixture of a conductive material of carbon soot (carbon black), in such a manner that signal information as geometric variations to be recorded. This recording medium can be produced without the need to deposit a thin metal film, since the recording medium itself is conductive and an electrostatic capacitance is formed between the electrode of the scanning needle and the recording. In addition, the fine carbon black powder is essentially completely enclosed by the resin, so that no dielectric layer is necessary either. This type of recording medium is easier to produce and at a lower cost.

When the recording medium made of conductive resin composition Now installed in a playback system and used for a longer period of time for playback, its surface is covered by the Your touching stylus is worn out. This results in a deformation of the geometric changes or Dimples formed on the recording medium so that the magnitude of the capacity changes also changes. In order to reliable playback is not possible. Especially when a video disk for still image playback or for extremely slow motion playback (freeze frame) is used, a certain section of the plate is repeatedly in contact with a stylus, which loads it about fifteen times per second at a pressure of 400 to 500 bar, so that there is considerable wear

EPO COPY

the plate surface results. In addition, the common conductive resin masses are sen. not very easily deformable.

There are extensive investigations with conductive resin compounds
has been made, which for records of high informci
density are suitable, and especially with lubricants that, were added to the resin composition. It turned out
that some lubricants do not show a satisfactory lubricating effect and show breeding effects, so that a "deterioration of the reproduction cannot be avoided. On the other hand, some lubricants produce disadvantages insofar as
Resin compounds with such lubricants are not satisfactory in continuous kneading devices or extruders
let knead or are not suitable for processing in compression molding machines.

It is therefore an object of the present invention to provide high density information recording media made of a conductive resin composition with a special lubricant. Another object of the invention is ^Au:: - to provide record carrier of electrostatic high density information using capacity in which the signal information is recorded by means of geometric changes and in which the geometrical changes are virtually not deformed, since the recording medium is resistant to wear and thus ensures reliable reproduction of the signal information.

The present invention proposes dimethylpolysiloxane as a lubricant in conductive resin compositions for recording media high information density. Dan means in particular that the present invention provides a recording medium with high information density of the electrostatic capacity type containing a recording substrate, on which signal information is recorded as geometric changes, the substrate being made of a conductive resin compound which is a thermoplastic resin, a

BATH ORIGINAL

3AU053

- ο -

Share of 5 to 30 percent by weight, based on the thermoplastic. ~ STIC resin, a le itfä ELIGIBLE material and a dimethyl - polysiloxane lubricant comprises a viscosity of less than 50 mPa.s at 25, wherein the lubricant in a proportion of 0.3 to 2.0 weight percent, based on the thermoplastic resin is contained. The term "recording medium with" high information density "is to be understood here to mean video disks or digital records.

As already described, the conductive resin composition for recording media of high information density contains dimethylpolysiloxane as a lubricant. The dimethylpolysiloxane used in practicing the invention should have a viscosity of less than 50 mPa.s at a temperature of 25. The viscosity is preferably not greater than 40 mPa.s and the range from 10 to 30 mPa.s. is particularly preferred. The Vis \ meet kositäts request, the dimethyl polysiloxane \ should not have a degree of polymerization of the 60th The ^Λ dimethylpolysiloxane is used in an amount of 0.3 to 2.0% by weight, preferably 0.45 to 1.5% by weight based on the thermoplastic resin contained in the conductive resin composition.

If the viscosity of the dimethylpolysiloxane exceeds the above value, no satisfactory wear behavior can be achieved. When the mass especially for the production of a video disc is used, the signal-to-noise ratio deteriorates, After a few tens of minutes of extremely slow motion or still image playback in an attempt and there may even be tracking errors caused. On the other hand, if the dimethylpolysiloxane has a small Has a viscosity of, for example, 2 mPa.s, the wear resistance of the recording medium obtained in this way deteriorates .

As already stated, the proportion of lubricant is from 0.3 to 2.0 percent by weight of the thermoplastic used

EPO COPY

elastic resin. Larger proportions can reduce wear resistance increase slightly, but the dimethylpolysiloxane tends to increase Compression molding for exudation and hangs on the mold surfaces at. Those to be produced on a recording substrate geometric changes cannot be precisely formed so that tracking errors are caused. on the other hand A lower proportion also results in a lower effect of the addition of DimethyTpoTysiloxane.

The thermoplastic resins useful in the invention include for example vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, Vinyl chloride-ethylene copolymers, vinyl chloride-propylene copolymers, Vinyl chloride-alkyl acrylate copolymers, acrylonitrile-styrene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers grafted with vinyl chloride and the like.

The conductive material used in the conductive resin composition is typically carbon black. Other materials including Metals such as copper, gold, platinum and organic materials such as polyacetylene can also be used in powder form. Around to give the mass a suitable electrical conductivity, however, the conductive material is generally added in an amount of 5 to 30 percent by weight of the thermoplastic resin the proportion may depend on the type of conductive material, the type of thermoplastic resin and the purpose of use.

In addition to the three essential ingredients listed, the additives normally used for these purposes or Additives can also be added to the mixture, in proportions that have the desired effect of the essential ingredients do not hinder. For example, heat stabilizers, plasticizers, other lubricants and the like are for such additives. cited.

The conductive resin composition is prepared in the usual manner in the art. For example, a predetermined amount

EPO COPY

"■ ' - ■ 34H053

thermoplastic resin with predetermined amounts of dimethylp'oTysiloxa'n and other ingredients are stirred in a mixer with high stirring speed until the system is on 80 ° to 135 ° C is heated, whereupon a predetermined amount of carbon black or similar conductive material is added and is mixed further. The resulting mixture is in one appropriate pelletizer pelletized. An optical disc or a record is then pressed from the pellets. These Mixing, pelletizing and pressing processes are well known in the art and require no further description. -. '"

The invention is explained in more detail using exemplary embodiments:

Example 1:

100 parts by weight of ethylene-vinyl chloride copolymer with a average degree of polymerization of 430 and an ethylene content of 1.5% (VE-N from Tokuyama Sekisui Ind. Co., Ltd.), 5 parts by weight chlorinated polyethylene (Elaslen 301A from Showa Denko Co., Ltd.), 5 parts by weight of dibutyl tin mercaptan ester stabilizer (STANN JF-95K from Sankyo Organic Chemicals Co., Ltd.), 1.5 parts by weight polyester lubricant (Loxiol G-70 from Nippon Henkel Co., Ltd.), 0.5 part by weight of an ester of fatty alcohol and dibasic acid (Loxiol G-60, Nippon Henkel Co. ", Ltd.) and 0.4 parts by weight of dimethylpolysiloxane (KF-96 from Shinetsu Chem. Co., Ltd.) with a viscosity of 30 mPa.s at 25 ° C. were poured into a 20 l Henschel mixer and at high stirring speed mixed until it was heated to 110 ° C. The mixer turned on at a slow speed operated to cool the contents to 70 C, there were 20 parts by weight of conductive carbon black (ketjen black EC, from Japan EC, Ltd.) and mixed at 110 fifteen minutes. The mixer was then continued to operate at a lower speed until the contents had cooled to 50 ° C. That

- 34K053

The resulting mixture was made using a Model PR-46 Kneader of Buss Co., Ltd. Switzerland, pelletized. The resulting .Pellets were pressed in a pressing device for video discs, to make video disks containing video signal information possessed in spiral grooves on their surface.

Embodiment 2:

The general procedure according to Example 1 was repeated using 0.4 parts by weight of dimethylpolysiloxane with a viscosity of 20 mPa.s at 25 ° instead of that used in Example 1 -Dimethy! Polysiloxane and video disks were made.

Embodiment 3:

The general procedure of Example 1 was repeated using of 0.4 parts by weight of dimethylpolysiloxane with a viscosity of 10 mPa.s at 25 ° instead of that used in Example 1 Dimethyl polysiloxane and video disks were made.

Embodiment 4:

The general procedure of Example 2 was repeated, but was the proportion of dimethylpolysiloxane was 0.7 part by weight, and video disks were produced.

Embodiment 5:

The general procedure of Example 2 was repeated, but was the proportion of dimethylpolysiloxane was 1.5 parts by weight, and video disks were made.

Embodiment 6:

"The general procedure of Example 1 was repeated using of 0.4 parts by weight of dimethylnolysiloxane with a Viscosity of 2 mPa.s at 25 C instead of the dimethyl polysiloxane used in Example 1, and video boards were produced.

_E PO COPY

Comparative example 1:

The general procedure of Example 1 was used of 0.4 parts by weight of dimethylpolysiloxane with a viscosity of 50 mPa.s at 25 was repeated instead of that used in Example 1 Dimethyl polysiloxane and video disks were made.

Comparative example 2: -

The general procedure of Comparative Example 1 was used of 1.5 parts by weight of dimethylpolysiloxane of the same kind and video disks were prepared.

Those obtained in the examples and comparative examples given Video disks were compared for their malleability. The disks were then subjected to a still image reproduction test using .. Subjected to a period of one hour in order to determine the degree of wear or the deterioration in the signal-to-noise ratio. During the investigation, a Y signal-to-noise ratio was established measured on each plate at gray 50 IRE, which was recorded at a point with a running time of 54 minutes from the outermost Trace of the video disc. The deterioration in the signal-to-noise ratio was determined to be 10 to 12 video disks of the respective examples and comparative examples were examined. Each plate was examined three times, with the lane being changed every hour. 30 to 36 measurements were made in total carried out on the video disks of each example and comparative example. The panels with a degree of deterioration below 3 dB was determined to be acceptable, while discs whose deterioration exceeded 3 dB were determined to be unacceptable, or in which a needle jump occurred. In the table below • is the percentage of deterioration in acceptable panels shown.

3.4 U O 53

T a b e 1 l_e

Dimethylpolysiloxane amount viscosity

(Parts by weight (mPa.s))

acceptable level of malleability

Ex . 1 0.4 30th 2 0.4 . 20th ~ 3 0.4 10 4th 0.7 20th 5 1.5 20th 6th 0.4 2 Cf.
Ex I 1 0.4 50 2 1.5 50

61 moderate 72 Well 45 Well 100 Well 100 moderate 28 ■ good 25th moderate not measurable bad

As the above results show, using ~ Dimethylpolysiloxane within the defined ranges of viscosity and the amount an improvement of recording media with high information density.

The viscosity values given are measured in cps and given, assuming 1 cps = 1 mPa.s.

COPV

Claims (3)

- patent claims - Π.y Recording medium for high density information from the electrostatic Capacitance type with a recording substrate on which signal information is recorded as a geometric change is, characterized in that the substrate is made of a conductive resin composition which is a thermoplastic resin, a conductive material in a proportion of 5 to 30 percent by weight based on the thermoplastic Resin, and a dimethylpolysiloxane lubricant with a viscosity less than 50 mPa.s at 25 ° C, wherein the lubricant is used in a proportion of 0.3 to 2.0 percent by weight based on the thermoplastic resin is. MAMIRZ · FINSTERWALÜ ■ HEYN · MORGAN ■ 800U MUNICH 22 · ROOF-Rr-KOCH SITIAfiSfC I TF.L. (089) 224? Il ■ TELEX 529 67? I ⁵ ArMF IAX K) UM) 2 <! / ii 75 HANNS-JÖRG ROTEHMtJND · / 000 STU) TGART SO (OAD CANNaTAlT) - '3FEl UERGSTn. 23/25 TLL- lO / M) ^r ili / 2 01 ■ - ■ -.- - 4
ν .i.- ^{..: ";: -"} '"34H053 K - 2 - 2. Recording medium according to claim 1, characterized in that the conductive material carbon black (carbon black) is. 3. Information carrier according to claim! or 2, characterized in that the dimethylpolysiloxane has a viscosity in the range from 10 to 30 mPa.s at 25 ° and is used as a proportion of 0.45 to 1.5 percent by weight, based on the thermoplastic resin. *} ' EPO COPY