Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
  • B29C66/41—Joining substantially flat articles ; Making flat seams in tubular or hollow articles
  • B29C66/45—Joining of substantially the whole surface of the articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/04—Dielectric heating, e.g. high-frequency welding, i.e. radio frequency welding of plastic materials having dielectric properties, e.g. PVC
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/01—General aspects dealing with the joint area or with the area to be joined
  • B29C66/05—Particular design of joint configurations
  • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
  • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
  • B29C66/112—Single lapped joints
  • B29C66/1122—Single lap to lap joints, i.e. overlap joints
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/73—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/731—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the intensive physical properties of the material of the parts to be joined
  • B29C66/7316—Surface properties
  • B29C66/73161—Roughness or rugosity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/73—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/739—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/7392—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
  • B29C66/73921—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic characterised by the materials of both parts being thermoplastics
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
  • B29C66/812—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
  • B29C66/8122—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B38/00—Ancillary operations in connection with laminating processes
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
  • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/83—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools
  • B29C66/832—Reciprocating joining or pressing tools
  • B29C66/8322—Joining or pressing tools reciprocating along one axis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2069/00—Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2909/00—Use of inorganic materials not provided for in groups B29K2803/00 - B29K2807/00, as mould material
  • B29K2909/08—Glass
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0072—Roughness, e.g. anti-slip
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2009/00—Layered products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B38/00—Ancillary operations in connection with laminating processes
  • B32B2038/0052—Other operations not otherwise provided for
  • B32B2038/0064—Smoothing, polishing, making a glossy surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
  • B32B2307/208—Magnetic, paramagnetic

Definitions

• the present invention relates to a method of surface treatment of a magnetic layer applied to a support such as, for example, PVC or polycarbonate, and more particularly the glazing and compaction of the magnetic layer .
• the applications of certain magnetic media involve recording information with a very high density.
• the layer of magnetic material When a magnetic medium moves relative to a magnetic head, the layer of magnetic material is in intimate contact with the head.
• the layer of magnetic material has numerous irregularities, and the magnetic head is in contact only with the convex parts of these irregularities.
• the existence of these irregularities causes, on the one hand, faster wear of the magnetic head used, and on the other hand, causes the recording and playback heads in direct contact with the magnetic layer, effects of distance which result in modulation of the amplitude or fluctuation of the signals recorded or read, thereby reducing the signal-to-noise ratio obtained.
• the causes of these disturbing irregularities in the surface of the layer are, as is known, irregularities or defects in the support sheet due for example to mineral fillers which sheet manufacturers often incorporate into the support material so that winding and handling leaf blocks be better.
• coating defects such as, for example, caused by malfunctions of the coating machine or of vibrations of the sheet transport system.
• Patent EP 139 403 describes a process for smoothing a magnetic surface in which the magnetic strip is passed between a rotating roller, of polished steel, and an elastic roller, with a suitable pressure and temperature.
• the magnetic medium is in contact with the polished steel roller, which gives it the desired gloss, while the support is in contact with the elastic roller which absorbs the irregularities of the support.
• the surface of the cylinders used has an arithmetic roughness of the order of 30 to 40 nm.
• Patent DE 3,727,197 describes very thin magnetic layers in which the percentage by weight of magnetic powder represents 66 to 90% of the magnetic layer and whose arithmetic roughness is between 10 and 15 nm.
• the subject of the invention is a simple method of surface treatment of magnetic layers making it possible to obtain an arithmetic roughness significantly lower than that which was obtained in the devices of the prior art.
• FIG. 1 schematically represents a device for implementing the method according to the invention in the process of manufacturing a high density magnetic card.
• the method according to the invention relates to a method of surface treatment of a magnetic sheet, comprising a support on which a magnetic layer is applied, on at least one of its faces, in which the magnetic sheet is heated and a pressure, said method being characterized in that the pressure is applied to each of the magnetic layers via a surface of polished glass.
• the glazing and the compacting of the magnetic layer are carried out through the use of glass plates which are brought into contact with the magnetic layer.
• glass plates which are brought into contact with the magnetic layer.
• the magnetic layer can be by way of example, as described in patent application FR 88 14219, obtained in the following manner: the magnetic particles used are particles of hexaferrite of Ba or Sr having a high coercive field, greater than 4000 Oe and preferably, greater than 5000 Oe. Such a high coercive field ensures the security of recorded information which cannot be erased by common external fields, while retaining the ability to rewrite by overwriting.
• a preferred method for preparing hexaferrites is that which is the subject of patent application FR 88 14221.
• particles of Ba or Sr hexaferrite having a shape index of at least 2: 1, a length between 0.1 and 0.3 ⁇ m, and a coercive field greater than 4000 Oe.
• the medium comprises a binder formed from a highly crosslinked three-dimensional polyurethane and a polytetrafluoroethylene optionally comprising polyethylene.
• the highly crosslinked three-dimensional polyurethane is formed from (a) a branched polyol of average molecular weight less than 4000 containing at least 8% by mass of OH groups and (b) of a prepolymer of an isocyanate comprising at least three isocyanate functions.
• Aromatic or aliphatic polyester polyols or polyether polyols can be used as the polyol.
• any compound usually used in polyurethane chemistry can be used, optionally as a mixture, insofar as it has at least 3 isocyanate groups.
• Such compounds can be obtained, for example, from 3 moles of an apliphatic or aromatic diisocyanate and from one mole of a trivalent alcohol such as glycerol, hexanetriol or trimethylolpropane.
• the mixture of binders is present in the magnetic recording medium in an amount of 10 to 60 g per 100 g of magnetic particles.
• the magnetic medium further comprises, as it is known, a number of additives such as surfactants, lubricants, pigments, etc. These additives must not be liable to exude from the layer and disturb the surface. It is known to introduce lubricants into the magnetic layers, in order to reduce the coefficient of friction between the layer and the head, to reduce the wear of both, and to improve the sliding properties. of the diaper.
• Liquid lubricants are not suitable, since they tend to exude from the magnetic medium on increasing the temperature, and in particular when the final treatment of the magnetic support requires high temperatures.
• solid lubricants such as those based on polytetrafluoroethylene (PTFE)
• PTFE polytetrafluoroethylene
• they are incompatible with the magnetic binder compositions usually used and contribute to reducing the cohesion of the magnetic medium.
• PTFE polytetrafluoroethylene
• they are poorly dispersed, form agglomerates and give non-homogeneous compositions which, when using the magnetic medium, allow particles of lubricant to escape.
• a powdered polytetrafluoroethylene is preferably used as a lubricant, optionally containing polyethylene, in which more than 90%, and preferably more than 99% of the particles, have a size of less than 3 ⁇ m, at a rate of less than 2% by mass relative to the mass of magnetic particles.
• Vydax DuPont de Nemours under the name of Vydax, provided that it meets the particle size requirements indicated above.
• the other additives are those commonly used in magnetic recording media.
• One or more surfactants are essential to ensure wettability, dispersibility and spreading the dispersion. It is advantageous to use a surfactant which is chemically attached to the surface of the magnetic particles.
• a polycarboxylic acid ester or a complex organic phosphoric acid ester can be used, for example.
• a vinyl copolymer based on vinyl chloride comprising OH groups can also be used as a dispersing agent. Such a copolymer generally comprises from 70 to 90% of vinyl chloride, the other monomers being chosen from vinyl acetate, polyvinyl alcohol, and acrylic or methacrylic esters optionally carrying hydroxyl groups.
• the quantity of compounds containing isocyanate groups must be calculated so as to take account of the OH groups of the vinyl copolymer, which must also be completely crosslinked in the three-dimensional network of the polyurethane.
• an alkylphenoxypolyethoxyethyl ester of phosphoric acid is used, in an amount of 3 to 8 g per 100 g of magnetic particles and a vinyl copolymer in an amount of less than 10% by mass relative to the total binder.
• the binder composition comprises the usual additives such as abrasive powders such as Al 2O3 or Cr2O3, pigments, in the form of a fine powder or colloid, such as carbon black to color the layer and silica to improve the quality and stability of the dispersion.
• abrasive powders such as Al 2O3 or Cr2O3, pigments, in the form of a fine powder or colloid, such as carbon black to color the layer and silica to improve the quality and stability of the dispersion.
• it may optionally contain agents to promote crosslinking, depending on the binder used and the kinetics that are desired.
• a coating dispersion is formed by mixing the magnetic particles, the various components of the binder and the additives, in the presence of solvents.
• Solvent mixtures known in the art of magnetic dispersions are used.
• the useful solvents there may be mentioned esters such as methyl acetate, ethyl acetate, isopropyl acetate, tetrahydrofuran, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, nitromethane , nitroethane, dichloroethane, etc.
• the useful quantities of solvents can be determined by the technician depending on the desired results, the particular compounds of the dispersion and the equipment used.
• the binder composition is then applied to a film support.
• this film support must therefore be compatible with the other plastic sheets constituting the card; it must in particular be able to be heat welded with these sheets. It also contributes to the final properties of the card; it must therefore be dimensionally stable, temperature resistant and elastic. Any polymer plastic support that meets these requirements can be used; it can be hot-stickable on the plastic sheets constituting the card, with or without an additional adhesive layer.
• the magnetic particles are optionally oriented longitudinally by any known method, then dried.
• the layer obtained has a thickness in the dry state less than 10 ⁇ m and preferably less than 6 ⁇ m.
• the glass used will generally be a polished glass whose arithmetic roughness can reach 3 to 4 nm and which must have certain characteristics. It must indeed be able to withstand thermal shock (particularly when performing heating by high frequency) as well as compression. You can use a tempered glass or a ceramic glass like Corning Vision for this purpose.
• the thickness of the glass plates can be example title between 1 and 5 mm.
• a pressure and a given temperature are then applied (in the case of the high frequency press, the temperature rise occurs during the application of the high frequency which causes molecular excitation in the support (example: PVC, polycarbonate ) or in the magnetic layer.
• the temperature which must be higher than the glass transition temperature of the binder forming, in part, the magnetic layer, is generally between 80 and 200 ° C. and, in the case of a binder such that three-dimensional polyurethane is between 130 and 190 ° C.
• the pressure varies depending on whether a thermal press or a high-frequency press is used and can vary between 100 and 2000 N / crn 2.
• a magnetic layer is obtained whose arithmetic roughness is of the order of 5 to 10 nm.
• a sheet of a flexible material not reacting at high frequency, is placed between the glass plates and the jaws of the press in order to absorb the defects due to bad flatness of the surface of the jaws or of the surface of the glass plates, in contact with the jaw. Indeed, because of the pressure exerted, it is absolutely essential that there is no bending force exerted on the glass plates when they are under pressure.
• the polished glass surface comprises in one or more determined locations one or more inscriptions, either in relief or in depth, which will, when said plate of polished glass is applied to the magnetic layer, transferred to the magnetic support in an area that doesn’t . is not intended to receive information leads.
• a support is thus obtained, the magnetic layer of which comprises, in depth or in relief, one or more inscriptions in predetermined areas of the support.
• it may be commercial information intended to authenticate a magnetic card; the small thickness of the magnetic layer would in fact make any modification of the marking obvious.
• the magnetic card that we want to make is a high density magnetic card consisting of a support semi-rigid and dimensionally stable carrying on the major part of at least one of its surfaces a magnetic recording medium formed of magnetic particles.
• the card support and the magnetic medium itself must have elastic deformation, that is to say, be able to return to their original shape, even after repeated bending.
• the card must also be thermally stable to withstand normal environmental temperatures without deformation. For these reasons, we have chosen to make this polycarbonate card from several superimposed layers.
• This card therefore consists of a number of polycarbonate sheets between 2 and 10 so as to produce a sandwich whose thickness is between 400 ⁇ m and 1000 ⁇ m, one of these sheets at least supporting a magnetic layer.
• These polycarbonate sheets can, for example, be made of LEXAN (manufactured by General Electric Co).
• the thickness of each sheet varies between 25 and 200 ⁇ m.
• the magnetic layer is also coated on a polycarbonate support whose thickness varies between 25 and 75 ⁇ m.
• the thickness of the magnetic layer is of the order of 5 to 10 ⁇ m.
• the card is made from 4 layers of polycarbonate
• a first cutting is then carried out by appropriate means (11) so as to have a sandwich having the surface necessary to make 3 cards (or more depending on the dimensions of the press).
• a first weld (12) is made at each corner of the sandwich. This welding can be carried out for example by means of ultrasound.
• the sandwich is then introduced into a device with several stations essentially comprising a press for applying the high frequency (13), a press provided with a cooling circuit (14) and a device for cutting individual cards (15).
• the sandwich passes first between the jaws of the press (13) allowing the high frequency to be applied.
• At least one of the faces of the sandwich namely that which is in contact with the magnetic layer (if the sheet has a magnetic layer on each of its faces, two glass plates are used) is separated from the metal electrode by a glass plate whose thickness is of the order of 5 mm. In our embodiment, two glass plates are used regardless of the number of magnetic faces.
• the pressure is then established and finally welded by applying the high frequency. During this step, the temperature rises to reach a temperature higher than the glass transition temperature of the binder used in the magnetic layer, that is to say of the order of 170 ° C.
• the magnetic layer then adopts a surface state very close to that of the material directly in contact with said magnetic layer, in this case the polished glass.
• a certain pressure between 100 and 200 N / cm 2
• a magnetic layer is thus obtained, the arithmetic roughness of which is of the order of 5 nm. It therefore appears that the conditions necessary for welding the polycarbonate by high frequency make it possible to obtain the surface treatment of the magnetic layers.
• both the welding of the card and the surface treatment of the magnetic layer are carried out.
• the operating conditions are as follows:
• the sandwich is removed to a cutting station (15) where the individual cards are then produced.
• Such a surface treatment method improves not only the microroughness of the magnetic layer but also the macroroughness of this layer, the microroughness (of the order of 5 nm) being defined at the level of the magnetic layer whereas the macroroughness is defined at support level itself.
• Such a static surface treatment method is not limited to the manufacture of magnetic cards. It can also be used, in particular for the manufacture of magnetic disks.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing Of Magnetic Record Carriers (AREA)
• Paints Or Removers (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9371445

Family Applications (2)

Family Applications After (1)

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• 1988
  • 1988-10-18 FR FR8814220A patent/FR2638016A1/fr active Granted
• 1989
  • 1989-10-17 AT AT89420397T patent/ATE87762T1/de not_active IP Right Cessation
  • 1989-10-17 JP JP1511168A patent/JPH04501333A/ja active Pending
  • 1989-10-17 ES ES89420397T patent/ES2039920T3/es not_active Expired - Lifetime
  • 1989-10-17 WO PCT/FR1989/000539 patent/WO1990004844A1/fr not_active Application Discontinuation
  • 1989-10-17 EP EP89912110A patent/EP0439523A1/de active Pending
  • 1989-10-17 EP EP19890420397 patent/EP0369896B1/de not_active Expired - Lifetime
  • 1989-10-17 DE DE1989605763 patent/DE68905763T2/de not_active Expired - Fee Related

Non-Patent Citations (1)

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