Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
  • H01J29/86—Vessels; Containers; Vacuum locks
  • H01J29/89—Optical or photographic arrangements structurally combined or co-operating with the vessel
• • G02B1/105—
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/14—Protective coatings, e.g. hard coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods

Definitions

• the present invention relates to transparent articles and more particularly to a method of producing transparent articles having a coating thereon, e.g. to improve their abrasion resistance and/or optical properties.
• the invention relates particularly, but not exclusively, to the production of transparent articles for use as windows in display devices.
• Display units in articles such as calculators and mobile phones generally have a transparent (usually plastics) window with a thickness of at least 100 microns (e.g. 200 microns) which acts as a protective barrier for the display device yet allows the information displayed to be viewed by the user.
• a method of producing a transparent article comprised of a parent base substrate having a thickness of at least 100 microns and a surface coating of a transparent resin wherein the resin is applied to the base substrate by means of a jet printer.
• a transparent resin coating is applied to the transparent base substrate by means of a jet printer.
• Such printers provide a particularly convenient method of applying the coating (which may be continuous or discontinuous) since they may be operated under computer control to provide the coating on the desired areas of the substrate. Furthermore such printers are readily available and provide a relatively cheap means for the accurate application of the coating in the mass production of transparent articles.
• the substrate will have a thickness of at least 125 microns preferably at least 150 microns, more preferably at least 175 microns and most preferably at cast 200 microns. Typically the thickness will be at least 300 and more preferably at least 400 microns. Generally the thickness of the substrate will be at most 20 mm, preferably at most 15 mm more preferably at most 12 mm and most preferably at most 10 mm. Typically the thickness of the substrate will be at most 8 mm, more preferably at most 6 mm, even more preferably at most 5 mm and typically at most 4 mm.
• the thickness will be in the range 750 microns to 3 mm.
• the coating that is applied may for example be one which improves the abrasion resistance of the base substrate (a so-called “hardcoat”) and/or the optical properties thereof (e.g an anti-fog coating).
• the coating may incorporate a dye or pigment whilst still retaining its transparency.
• the jet printer is an ink-jet printer or a bubble jet printer. Most preferably the printer is an ink-jet printer. A particularly suitable printer is available from WEBER, model ML 500.
• An ink-jet printer has a plurality (e.g. 96) of irk-jets.
• the jets may be operated continuously or may be operated in accordance with a particular programmed pate for applying the coating.
• By operating the jets in accordance with such a program coating of selective areas of the substrate may be achieved For example portions of the substrate that need to be affixed to other members in order to form an assembled device can be selectively left uncoated, e.g. edge portions.
• the invention may be used for the coating of transparent substrates of relatively small size, e.g. having a longitudinal dimension of up to 20 cm and a transverse dimension of up to 15 cm. Such substrates may be fed in succession to the jet printer for the coating operation to be effected so that relatively small coated articles may be produced at a high rate.
• the invention may, however, also be used for the coating of larger substrates.
• a digital ink-jet printer having a number of printing heads is particularly suitable for the coating of larger substrates.
• the invention is particularly applicable to the application of coatings onto base substrates of a plastics material which may be a thermoplastics or thermoset material.
• plastics material which may be a thermoplastics or thermoset material.
• suitable plastics include polycarbonates, polyacrylics, polyesters and allyl carbonate (CR39).
• the transparent substrate may be of glass.
• the resin to be applied by the jet printer is preferably formulated as a solution or suspension in an appropriate carrier liquid. It is particularly preferred that the solution or suspension has a viscosity of 50 to 500 cP as measured on a Brookfield RVT Viscometer, Spindle No. RV2, 20 rpm at 25° C. Solutions or suspension of such viscosity are particularly suitable for formation of a coating by a jet printing technique
• Various types of resin may be applied by the technique of the invention, e.g. polyurethanes, acrylates siloxanes, acrylics and combinations thereof. It is particularly preferred that the resin is cross-linkable so as to be capable of forming a cured coating on the base substrate.
• Cross linking may, for example, be by means of air drying, uv curing or thermal curing.
• Hardcoats will generally be based on either acrylate or siloxane chemistry and cured using either uv or thermal means.
• Anti-fog coatings may for example be based on hydrophilic polyurethanes.
• a particularly preferred embodiment of the method of the invention comprises feeding transparent articles in succession to the jet printer and then through a drying tunnel and a curing station.
• the coating is applied at the printer and residual solvent is removed on passage of the substrates through the drying tunnel.
• the curing station effects cross-linking of the resin (preferably by uv curing) to form a coherent coating thereof on the transparent substrate.
• the thickness of the rein coating will depend on the intended application of the substrate and/or the nature of the coating but will generally be in the range of 5 to 100 microns, more preferably 5 to 50 microns. In the case of a “hardcoat” for improving abrasion resistance the coating thickness will typically be 5-8 microns since increasing the thickness does not have any beneficial effects on the coating performance and may in fact be counter productive. In contrast the performance of anti-fog coatings is improved by increasing coating thickness so that values in the range 10 to 20 microns or higher may be most beneficial.
• the method of the invention is performed in a “clan” environment, i.e. an environment that is substantially free from dust and other atmospheric components which may detrimentally affect the coating process by affecting the binding of the resin to the base substrate and/or its subsequent curing.
• a “clan” environment i.e. an environment that is substantially free from dust and other atmospheric components which may detrimentally affect the coating process by affecting the binding of the resin to the base substrate and/or its subsequent curing.
• the method of the invention is carried out in an environment separated from the ambient atmosphere.
• This may be achieved by opening the method of the invention in a “tent”, particularly a tent which has its own integral air/gas supply.
• the tent atmosphere may be modified, e.g. to provide an inert atmosphere for the coating process and/or a positive tent pressure (i.e. a pressure above atmospheric) to exclude contaminants.
• the resin may be one which is intended to provide an abrasion reset coating on the transparent base substrate and/or improve the optical properties thereof e.g. by way of being an anti-glare or anti-mist coating.
• the invention is particularly applicable to the application of abrasion resistant coatings to plastics substrates.
• Abrasion resistance may be measured in accordance with ASIM D-1044 in which a CS10F standard wheel having a 500 gram load is rotated 1000 times on a sample. The HAZE value of the abraded substrate may then be measured.
• Uncoated acrylic and uncoated polycarbonates substrates give HAZE values of around 30% and 33% respectively (the exact value depending on thickness and source of supply).
• Use of the invention to apply a “hardcoat” to these substrates mikes it possible to reduce these HAZE values to less than the 10% maximum permitted by the ASTM specification. It is possible, for example, to reduce the HAZE values to and typically to 24% and even lower in certain cases, e.g. 1-1.5%.
• a display device having a display window which is a transparent article in accordance with the second aspect of the invention.
• the method of the invention may for example be used to produce a window (for a mobile phone or other item with a display device) from a pre-moulded transparent substrate to which is then applied a transparent coating in accordance with the method of the invention.
• the transparent substrate may also be provided with an opaque boarder formed of appropriately pigmented resin.
• the boarder may be applied to the same side as, or opposite side to, that to which the transparent coating has been applied.
• the opaque border may be applied by pad coating or by means of a jet printer. The use of a jet printer will be particularly convenient when the opaque boarder is applied to the same side of the substrate as the transparent coating.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Laminated Bodies (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Glass Compositions (AREA)
• Surface Treatment Of Optical Elements (AREA)
• Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
• Ink Jet Recording Methods And Recording Media Thereof (AREA)

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Citations (4)

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• 2001
  • 2001-07-19 GB GBGB0117568.6A patent/GB0117568D0/en not_active Ceased
• 2002
  • 2002-07-19 CN CNB02814399XA patent/CN1246707C/zh not_active Expired - Fee Related
  • 2002-07-19 JP JP2003514298A patent/JP2004536338A/ja active Pending
  • 2002-07-19 AU AU2002313530A patent/AU2002313530A1/en not_active Abandoned
  • 2002-07-19 EP EP02753124A patent/EP1410075B1/en not_active Revoked
  • 2002-07-19 PT PT02753124T patent/PT1410075E/pt unknown
  • 2002-07-19 WO PCT/GB2002/003308 patent/WO2003009013A2/en not_active Ceased
  • 2002-07-19 US US10/484,190 patent/US20040191414A1/en not_active Abandoned
  • 2002-07-19 DK DK02753124T patent/DK1410075T3/da active
  • 2002-07-19 DE DE60209914T patent/DE60209914T2/de not_active Expired - Lifetime
  • 2002-07-19 ES ES02753124T patent/ES2260466T3/es not_active Expired - Lifetime
  • 2002-07-19 AT AT02753124T patent/ATE320612T1/de active
• 2009
  • 2009-10-06 US US12/573,908 patent/US8722139B2/en not_active Expired - Lifetime

Patent Citations (4)

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