FR2544534A1 - HIGH DENSITY INFORMATION CARRIER MADE OF RESIN COMPOSITION COMPRISING CARBON BLACK PROCESSED IN A SPECIAL WAY - Google Patents

Abstract

THE OBJECT OF THE INVENTION IS TO SUPPORT HIGH DENSITY INFORMATION OF THE ELECTROSTATIC CAPACITY TYPE. IT INCLUDES A RECORDING SUBSTRATE ON WHICH SIGNAL INFORMATION IN THE FORM OF GEOMETRIC VARIATIONS IS RECORDED; THE SUBSTRATE IS A CONDUCTIVE RESIN COMPOSITION WHICH INCLUDES A THERMOPLASTIC RESIN AND A PREDETERMINED QUANTITY OF BLACK CARBON PARTICLES CLEARED FROM THE ASH; THESE PARTICLES ARE SURFACE TREATED WITH A FATTY ACID CONTAINING 12 TO 24 ATOMS OF CARBON. APPLICATION: VIDEO, AUDIO-DIGITAL RECORDINGS WITH MINIMUM WEAR OF THE INFORMATION MEDIA.

Description

1 - High density information carrier made in one

  resin composition comprising a treated carbon black

tee in a special way

  The present invention relates to systems for

  provision of electrostatic capacity type information

  variable and, more particularly, information

  high density mages such as a video disc

  or audio-digital discs on which

  Signals are recorded as a vari-

geometric

  In some information retrieval systems,

  the signal information is coded in the form of

  geometric variations or craters in a plan or rationale.

  spiral wound or in concentric planes or grooves

  on an information medium The support on the-

  which the information signals were recorded is read as

  follows me When a reading style, for example a diamond

  comprising an electrode performs an exploration with

  port to a saved track of the medium, capacitive variations appear between the playback style and the medium due to geometric variations of the plane or

of the groove.

  Several types of information media have been proposed.

  for use in a rendering system

  information of the type described above with an electro-

  In a first type of such a medium of information,

  tions, an electrode is provided on the surface of a recording substrate on which the geometric variations

  are press-molded according to the information signal.

  This allows the establishment of an electrostatic capacitance

  between the recording electrode and the style electrode.

  For example, the recording substrate is covered with a thin metal film having several tens of nanometers in thickness and a dielectric layer

  also having several tens of nanometers thick

2-

  covering the metallic film The role of the

  The dielectric electrode is to prevent the short-circuiting of the electrodes and to increase the dielectric constant between the electrodes. The information carrier of the type just described requires a certain number of stages of manufacture, especially a press molding. of the information substrate, depositing a thin metallic film,

  the deposition of the dielectric layer etc. Thus, the manufacturer

  cation is complicated and tedious and also requires

  manufacturing equipment with a fairly large capacity

  As a result, production costs also become

very important.

  Another type of known medium for recording information in the form of an electrostatic capacitance

  is the one obtained by press molding of a com-

  conductive plastic position comprising a resin such as polyvinyl chloride mixed with a conductive material such as carbon black so that the

  information signal is recorded as a vari-

  geometric information. Such a medium of information is made

  without having to deposit a thin metallic film because the information carrier itself is conductive, and an electrostatic capacitance is formed between the electrode

  reading style and information support In-

  the fine powder of carbon black is practically

  covered with resin so that no dielectric layer

  that is necessary Due to the above, this type of information carrier is very simple to manufacture and

  can be with a low cost price.

  However, especially when using card black

  As a conductive material, the following problem is encountered: given the process for producing ordinary carbon black, it is inevitable that relatively large proportions of impurities or ash remain.

  in carbon black These impurities tend to

  appear or rush on the surface of the articles of

  During or after molding, so that irregularities appear on the surfaces of the support

  information or leads These irregularities have an ef-

  unfortunate fetish on reading characteristics.

  Another problem is that when the information carrier formed of a conductive resin composition

  comprising carbon black is mounted in a system of.

  reading and is read for a long time, its surface

  as well as the reading style itself are worn out by

  tact the said surface and the reading style This results in a deformation of the geometric variations or

  craters formed on the media of information, in

  as for a change of capacitive variations Thus, a reliable reading is not possible In particular, when subjecting a video disc to a stop reading on an image, a given part of the disc repeatedly comes into contact with the reading style at a pressure of 400 to 500 kg / cm 2 and at a frequency of 15 times per second or about a speed of 10 m / second, which causes considerable wear of the disc surfaces and the reading style. such a disc can be overcome

  to some extent by the addition of an appropriate type

  asked for lubricant On the other hand, the wear of the reading style

  ture proves to have a close relationship with the characteristics

  ticks the surface of carbon black In general, the

  Carbon black used for such purpose is present

  it is several tens of% by weight with respect to the resin Even if the lubricants are contained in conductive resin compositions, it is impossible to

  that all carbon black particles are always

  days covered with lubricants The presence of

  carbon black particles with little lubricating

  relying on absorption or adsorption is the main reason

  shortening of the service life of the reading style

ture.

  Accordingly, the main objects of the invention are to provide

  high-density information carriers

  solving the problems mentioned above;

  high-density information

  effectively prevent the wear of a playback style and the recording surfaces in contact therewith, by ensuring a prolonged use of the style and the recording medium

  high density information carriers as-

  secure-reliable information read operations for a long time; and

  high-density information carriers

  bricks into resinous conductive compositions of

  that these information carriers are made simple-

  and without the use of complicated techniques.

  The present invention is characterized by the use

  carbon black removed from the combined ashes

  In particular, the invention provides an electrostatic capacitance type high density information carrier, which comprises a recording substrate on which signal information in form is recorded. geometric variations, the substrate being

  made of a conductive resin composition that

  takes a thermoplastic resin and black particles

  carbon removed from ashes which are treated

  by a fatty acid having 12 to 24 carbon atoms, the

  ash-free carbon black being used for the sake of

  5 to 30% by weight relative to the weight of the thermoplastic resin. Preferably, the fatty acid is applied to the carbon black particles in a proportion of 1 to 10% by weight.

  weight in relation to the weight of the black particles of

  bone. The single figure of the appended drawing is a graph showing the relationship between the diagonal length of a

  contact face of a reading style and the time of re-

-

  production for various types of recording.

  As described above, the supports

  high density information, according to the present invention.

  are made of a conductive resin composition

  trice comprising a thermoplastic resin and

  carbon black particles having undergone a specific treatment

  cial. Thermoplastic resins that are suitable for

  the implementation of the invention are, for example, a

  vinyl chloride sine, vinyl chloride / vinyl acetate copolymers, vinyl chloride / ethylene, vinyl chloride / propylene, vinyl chloride / alkyl acrylates, acrylonitrile / styrene / vinyl chloride and ethylene / acetate copolymers vinyl grafted with vinyl chloride, etc. To prepare the carbon black rid of

  ash and superficially treated, used according to the invention.

  tion, we proceed as follows: the black particles of

  carbon available commercially contain normal-

  approximately 1% ash with

  Ca, Na, K, Fe, Ni, Al, Cu, Zn, Mg, V and

  As will be seen in the examples which follow, these particles of carbon black are placed in an aqueous acid solution and the mixture is stirred sufficiently and then the solution is separated as such, for example by decantation to collect the particles. The particles are washed. thus collected sufficiently with pure water Then, the washed particles are neutralized with an alkaline solution such as an ammoniacal solution,

  then wash with water twice or more.

  complete the ash removal treatment On

  note that carbon black particles

  ashes must be advantageously

  a p H from 5 to 10 The particles of carbon black disembark

  Ashes are activated in such a way that the p H tends to fall A too low p H adversely affects the thermoplastic resins and especially on a resin of

  vinyl chloride especially when heating the composi-

  resin for shaping or molding.

  The acids used in this process may be any inorganic acids such as chloroacids.

hydric, nitric, and the like.

  The particles of carbon black are then mixed

  removed from the ash with a fatty acid containing 12 to 24 carbon atoms in a proportion of 1 to 10% by

  weight in relation to the weight of the black particles of

  and stir for a sufficient time.

  mixing is then carried out under a pressure of 18.6 to 60 millibars at a temperature of 100 to 2000 ° C., preferably 110 ° to 100 ° C. Then, it is heated again in an atmosphere of inert gas such as nitrogen at a temperature of 250 to 6000 C for 1 to 10 hours By this heating, the acid

  fat is combined with carbon black by ester bonds.

  Thus carbon black is chemically modified.

  As concrete examples of fatty acids, mention may be made of

  saturated acids, such as tridecyl acids, my-

  pentadecyl, palmitic, heptadecyl, stearic,

  acid, nonadecanoic, arachic, behenic, lignoceric, and the like, and unsaturated acids, such as oleic acid. Among these acids, stearic acid is preferred.

  because of its abundance on the market and its

than.

  By this treatment the carbon black becomes beautiful.

  blow more compatible with thermoplastic resins and

  it is therefore dispersed more evenly in the residence.

  This reduces the risk of direct contact between

  carbon black particles and the style of reading.

  -Even if a direct contact takes place, the style will be less worn

  by contact with carbon black as a result of lubricating

  superficial fication given to carbon black.

  In the practice of the invention, it is preferred that the starting carbon black particles have a

  contact area and a porosity corresponding to an ab-

  sorption of DBP (dibutyl phthalate) 250 to 450 and one

absorption of I 2 from 800 to 1400.

  For the production of recording items such as video or audio discs, the modified carbon black particles are mixed with

  ash with thermoplastic resins in a proportion

  5 to 30% by weight with respect to the thermosetting resin.

  plastic to ensure good conductivity of the com-

  resulting position Of course, one can also add

  normally used in this industry.

  in proportions that do not interfere with the effects of

  As examples of such additives, it may be possible to

  thermal stabilizers, plasticisers and similar

lar.

  Normally the conductive resin composition is granulated by suitable means. The granules are used for the press molding of a video or audio disc, as is customary. All these techniques of mixing, granulation and press molding are well known and ,

not going to continue the study.

  The present invention is illustrated by the examples

  ples and comparative examples, descriptive and not limited

hereinafter.

Example 1

  in a 5-liter flask containing 2 liters of a 5% solution of hydrochloric acid, 100 g of carbon black conductive particles having a bulk density of 0.17 g / cm 3 are placed, a loss of weight at heating of 1.46%, a p H of 9.6, an absorption

  of DBP oil of 320 ml / 100 g and an absorption of 12

  1269 mg / g (available from Cabot Co Ltd U S A) and the mixture is sufficiently mixed with stirring.

  by settling and then adding about 2 liters of water

  The water is then decanted off.

  The washing is repeated with pure water at least three more times, then neutralized with an ammoniacal solution and washed with pure water at least twice. By the technique described, the carbon black is freed from ashes. The

  carbon black thus treated has a carbon content

  from 0.04 to 0.05%, a pH of 6.7 to 7.0 and a thermal stability of 10.5 minutes and contains metal components at 46 ppm Ca, 8 to 28 ppm. Na, less than 5 ppm K, 16 ppm Fe, less than 5 ppm Ni, 114 to 121 ppm Al, less than 5 ppm Cu, less than 5 ppm Zn, less than 2 ppm Mg and less The thermal stability is determined by a method using the "Plastograph Plasti-Corder" manufactured by Brabender Co.

  Ltd, Germany, measuring the time before a

  Congo red reactive pierce does not turn blue.

  100 g of carbon black particles are mixed

  removed from the ashes with 5 g of a sterile acid

  the mixture is sufficiently mixed and stirred.

  then mixing in a rotary evaporator under a pressure

  from 18.6 to 60 millibars, at a temperature of 110 C and then heated in an electric oven for 4

  hours in an inert gas atmosphere.

  ge, carbon black particles are reacted with

  stearic acid through the ester bonds.

  Then, it is placed in a mixer "Henschel" (trademark) of 20 liters and homogenized at high stirring speed until the mixture reaches a temperature of 110 C, 100 parts by weight of a copolymer

  ethylene / vinyl chloride having a degree of polymerisation

  430 and an ethylene content of 1.5% ("VE-N" of

  Tokuyama Sekisui Ind Co Ltd), 5 parts by weight of

  chlorinated lyethylene ("Elaslen 301 A" from Showa Denko Co Ltd), parts by weight of the mercapto-dibutyltin ester stabilizer ("Stann JF-9595" from Sankyo Organic Chemicals Co.

  Ltd), 1.5 parts by weight of an ester of molecular weight

  high ("Loxiol G 70" from Nippon Henkel Co Ltd), 0.5

  part by weight of an aliphatic alcohol ester and a dia-

-9

  (Loxiol G 60 from Nippon Henkel Co, Ltd) and 1.0

  by weight of dimethylpolysiloxane having a viscosity of 20 cp at 250 ° C. The mixture is then cooled to 70 ° C.

  by running the mixer at low speed

  te to this mixture 20 parts of conductive carbon black

  surface treated and homogenized at 110 ° C. for 1 minute.

  nute, then rotate the mixer slowly to

  as the temperature drops to 50 ° C The mixture is granulated

  in a PR-46 kneader from Buss Co Ltd, Switzerland.

  metals contained in the granules in a machine

  metal separation and place the granules in

  a video disc press for forming video discs.

  Comparative Example i is carried out as in Example 1 using untreated particles of carbon black instead of

  surface-treated carbon black and the preparation of

video.

  The carbon black particles used in this Comparative Example contain 0.94% ash, have a pH of 9.6 and a thermal stability of 7 minutes and contain 1120 ppm Ca, 32 ppm Na, less than ppm. of K, 55 ppm Fe, 6 ppm Ni, 265 ppm Al, less than 5 ppm Cu, 7 ppm Zn, 9 ppm Mg and less than 20 ppm V. Comparative Example 2 Example 1, except that the ash-free carbon black does not suffer from

  surface treatment with stearic acid More precise-

  The ash-free carbon black is dried in a rotary evaporator under a pressure of 20 to 60 millibars at a temperature of 1100 ° C. and then heated in the oven.

  an electric oven at 400 ° C for 4 hours in a

  mosphere of inert gas Then proceed as in

  Example 1 and video disks are obtained.

  The ash-free carbon black used in this comparative example contains 0.01 to 0.03% ash, a pH of 6.8 to 7.2, and a thermal stability of 9 minutes; it contains 50 ppm of Ca, 7 to 8 ppm of Na, less than 5 ppm of K, 5 ppm of Fe, less than 5 ppm of Ni, 44 to 49 ppm of Al, less than 5 ppm of Cu, less than 5 ppm Zn, less than 2 ppm Mg and less than 20 ppm V.

  We install the video discs obtained in the ex-

  example and in the comparative examples above, each

  in a reproductive tract and a reproductive

  continued to measure the diagonal length of the

  sliding contact surface of a reading style A par-

  from this result, the degree of wear of the style is determined.

  It should be noted that the degree of wear is higher for a

  longer diagonal length The results appear to be

  in the single figure on which the solid line

  set the results for the video disk according to example 1,

  the dashes-dots line corresponds to the video disc of the former

  Comparative example 1 and finally the two dots-dash

  corresponds to the video disk of Comparative Example 2.

  The results in the figure indicate that the

  that video according to the present invention ensures a very long

  the service life for the reading style However,

  with the video disk of Comparative Example 1, this

  is shorter and with the video disk of Comparative Example 2 it is much shorter In addition, the video disk of Comparative Example 1 which uses a black

  carbon removed from the ashes causes a

  However, the video discs according to Example 1 and Comparative Example 2 do not make a difference in the quality of the reproduced image, for example by interruption.

evidence of such deterioration.

  Briefly, the use of an undecorated carbon black

  Ash Damask translates into a life in service

  relatively long reading style but is at the origin

  a lowering of the quality of the reproduced image.

  When carbon black is simply stripped of ashes but without additional surface treatment 11 - with fatty acids, it can be considered that the duration of use of the reading style is shortened, although

  the reduction in the quality of the image is minimal.

  milking, the use of ash-free, surface-treated carbon black can significantly extend the service life of the style without reducing the quality

of the image.

Example 2

  the procedure is as in Example 1 except that

  tridecyl acid, myristic acid, pentadecylv palmitic, heptadecyl acid, is added to the palate of stearic acid,

  nonadecanoic, behenic, lignoceric or olel-

  that, and we form video discs We submit all these discs

  the same tests as before and we obtain

  results similar to those obtained with stearic acid.

12 -

Claims (6)

  A high-density information carrier of the electrostatic capacitance type, characterized in that   comprises a recording substrate on which are   registers the signal information as a variable   geometries, the substrate being manufactured in a   conductive resin position comprising a thermal resin   moplastic and carbon black particles   ash, which has undergone a surface treatment with a fatty acid containing 12 to 24 carbon atoms,   carbon black ashes and superficial-   being treated at a rate of 5 to 30% by weight   relative to the weight of the thermoplastic resin.   High density information carrier according to claim 1, characterized in that the ash-free and surface-treated carbon black particles are chemically combined with the fatty acid by ester bonds.   High density information carrier according to claim 1, characterized in that the fatty acid is Stearic acid.   4. High density information carrier according to claim 1, characterized in that after removal of the ashes, the carbon black particles have a p H from 5 to 10.   5. high density information carrier according to claim 1, characterized in that said fatty acid is used in a proportion of 1 to 10% by weight relative to weight of the carbon particles.   6 High density information carrier according to   claim 1, characterized in that said parties   Carbon black cells have a dibutyl phthalate uptake of 250 to 450 and an I 2 uptake of 800 to 1400.