Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00605—Production of reflex reflectors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00596—Mirrors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00865—Applying coatings; tinting; colouring

Definitions

• This invention relates to a method of producing an optical component and components produced thereby. It is known to use synthetic plastics materials for optical components and these have several advantages over traditional glass and crystalline materials, such as resis- ⁇ tance to thermal and mechanical shocks, lower production costs, reduced weight and greater design flexibility. Such plastics optical components are however, vulnerable to sur ⁇ face damage by abrasion, scratching and environmental con ⁇ ditions which often impair their function.
• SM ' OMFI opaque plastics material usually acrylonitrile-butadiene- styrene copolymers. This method is very costly and prone to production problems. It also produces a mirror-like product of lower reflectivity than is achieved by conven- tional silver or aluminium surfaces. Despite the use of a relatively inert plastics base material for the mirror the multi-metal layer electroplating process can also give rise to troublesome electrolytic corrosion problems when the mirror is exposed to adverse environmental conditions.
• a further technique involves thermal evaporation of aluminium on to the rear surface of an already coated transparent plastics material, the coating of which is abrasion resist ⁇ ant to a degreee and previously deposited by a separate and costly wet chemical process. Articles produced by this technique are limited by the size, shape and configuration of the basic coated plastics materials, usually in flat- sheet form, and are expensive by virtue of the multi-stage production methods involved.
• Vacuum assisted metal deposition onto untreated plastics material followed by a wet chemical coating process to confer abrasion resistance is also known but this is again costly and prone to optical faults.
• a method of making an optical component having specular re ⁇ flective properties from plastics material comprises apply ⁇ ing to the plastics material a face layer of hard glass or a substance having hard glass-like properties and subsequently
• the plastics material is preferably subject to a degreasing operation prior to applying the face layer, and the degreasing operation may -be carried out by subjecting the plastics material to vapourdegreasing in a fluorocarbon solvent and the material is then transferred to an ultra- sonically vibrated solution of the same solvent.
• a molecular cleaning operation is performed in a vacuum vessel after the degreasing operation.
• the face layer may be formed by applying a key coat layer of oxides of the material used for the spec ⁇ ular reflective material.
• the key coat layer may be applied by means of a magnetron sputtering operation in a vacuum vessel in an atmosphere of oxygen and argon at a pressure
• the vacuum vessel may be reduced to 1 x 10 ⁇ mbar pressure and argon gas is introduced until the pressure reaches 5 x 10 -4 mbar, oxygen then being added until the pressure
• the key coat is immediately applied by means of a magnetron sputtering operation using a target of the metal to be deposited on the key coat layer.
• the key coat layer is preferably of the order of 0.5 - 1.0 microns thick.
• the coating of reflective material may then be applied directly to the key coat layer and in this case the reflec ⁇ tive material may be applied by a DC magnetron sputtering operation.
• the coating of specular reflective material is chromium, and in which case the key coat layer is preferably a thin layer of oxides of chromium of between 0.5 to 1.0 microns thick.
• the coating of specular reflective material is aluminium, in which case the key coat layer is preferably a thin layer of oxides of aluminium of between 0.5 and 1.0 microns thick.
• a hard abrasive resistant coat may also be applied to the aluminium, and in this case a top coat may be applied by means of a layer of dielectric oxide of between 0.5 and 5.0 microns thick.
• the face layer may be formed by an in situ glass making opera- tion by co-reacting under plasma activated conditions typi ⁇ cal glass making chemicals such as a calcium carbonate, sodium carbonate and oxides of silicon. Such chemicals may be brought into a reactive state by bombardment with a high energy beam of electrons.
• the invention also includes within its scope an op ⁇ tical component formed by the method set forth.
• an opti ⁇ cal component having specular reflective properties comprises a platics material having a face layer thereon of glass or a substance having glass like properties and a specular layer of reflective material coated thereon.
• the plastics base material comprises a pol condensate polymer prepared by the interaction of a polyhydroxy compound with a carbonic acid derivative, typi ⁇ cally the reaction product of bis-phenol-A with either phosgene or diphenyl carbonate which is available commercial ⁇ ly under the Trade Name "Lexan” polycarbonate and manufact ⁇ ured by the General Electric Co. U.S.A.
• An appropriate shape and size may be obtained either by a conventional thermo ⁇ plastics injection process or by cutting to a given, desired profile from precision manufactured extruded sheet.
• the base material is vapour degreased in a fluoro- carbon solvent, typically "Arklon” P (ICI) for three minutes, then transferred to an ultrasonically vibrated heated solu ⁇ tion of the same solvent for a further three minutes for cleaning. A final vapour degreasing of three minutes dura ⁇ tion may be given.
• the plastics material is then transferred to an appropriate location jig in a process vacuum vessel, this operation being carried out under strictconditions of cleanliness.
• the vacuum vessel is sealed and pumped out to a pressure of 1 x 10 mbar. Argon is-then introduced until the pressure rises to 1 x 10 " mbar.
• a voltage of 1.5 kilovolts AC is then applied to electrodes situated within the vacuum vessel and in close proximinity to the base plas- -tics material surface which is to be processed.
• the glow discharge so initiated is held for a period of up to 20 minutes during which the plastics surface receives a 'mole ⁇ cular cleaning" and which treatment in effect although termed
• O PI cleaning provides a surface treatment which makes it more receptive to receive the coatinglayer as described below.
• a magnetron sputtering operation using a chromium target is then initiated within the vacuum chamber and the charged chromium atoms interact reactively with oxygen so as to deposit thekey coat layer of chromium oxides onto the surface of the adjacent polycarbonate.
• This layer consists of one or more oxides of chromium and possibly also the metal itself.
• the layer is preferably 0.5 - 1.0 microns thick.
• the oxygen supply is then discontinued and a coven- tional DC magnetron sputtering of chromium initiated at target power density levels which gradually increase from W/cm 2 to 12 /cm2.
• This gradual deposition of chromium onto the chromium oxide key coat layer ensures that a stress- free film is deposited. It is known in the art that thin layers of chromium are prone to either compressive or tensile stresses and care is necessary at this stage. Typically a reflective layer thickness of from 0.5 to 5.0 microns is applied.
• OMP it is not limited thereto.
• a more highly reflective alumium mirror can be produced in a similar manner with a reactively sput ⁇ tered aluminium layer which would be similar to the chro - ium layer and consist of alumium oxides and possible alu ⁇ minium metal itself, followed by a layer of alumium metal.
• a softer metal such as this, it may be neces ⁇ sary to apply a hard abrasion resistant top coat of a die ⁇ lectric oxide such as an oxide of silicon either by sputter- ing with the assistance of an RF field or by an electron beam evaporation. Both techniques are well known to those skilled in the art.
• a typical thickness range for this top coat would be 0.5 to 5.0 microns.
• the glass or glass-like top coat layers may be formed in a variety of ways such as by means of an in situ glass making operation by co-reacting under plasma acti ⁇ vation conditions typical glass making chemicals such as calcium carbonate, sodium carbonate and oxides of silicon.
• typical glass making chemicals such as calcium carbonate, sodium carbonate and oxides of silicon.
• conventional calcium/sodium/silicon glass may be formed on the surface of the plastics material.
• Alterna ⁇ tively alumino/silicon glass films and lead glass films can also be made in a similar way.
• Another method for depositing a glass layer is by the direct in vacuo vaporization of an already formed glass material e.g. borosilicate glass using electron beams or conventional electrical heating devices to induce vaporization.
• so called filled plastics material such as glass-filled, talc and chalk-filled, or
• O PI other mineral filled polypropylene materials are primarily designed to reduce cost and improve properties, the filler component can be co-reacted with substances in a vacuum chamber to improve bonding of the glass anchor coating.

Landscapes

• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Ophthalmology & Optometry (AREA)
• Mechanical Engineering (AREA)
• Physical Vapour Deposition (AREA)
• Laminated Bodies (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Optical Elements Other Than Lenses (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

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ID=10536991

Family Applications (1)

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Cited By (2)

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Citations (8)

Family Cites Families (4)

• 1983
  • 1983-01-26 GB GB838302165A patent/GB8302165D0/en active Pending
• 1984
  • 1984-01-20 CA CA000445714A patent/CA1246370A/en not_active Expired
  • 1984-01-20 IE IE138/84A patent/IE55013B1/en unknown
  • 1984-01-24 ZA ZA84518A patent/ZA84518B/xx unknown
  • 1984-01-25 GB GB08503825A patent/GB2152703B/en not_active Expired
  • 1984-01-25 NL NL8420019A patent/NL8420019A/nl unknown
  • 1984-01-25 AU AU24955/84A patent/AU576487B2/en not_active Ceased
  • 1984-01-25 DE DE19843490033 patent/DE3490033T1/de not_active Ceased
  • 1984-01-25 JP JP59500766A patent/JPS60500502A/ja active Pending
  • 1984-01-25 IT IT19314/84A patent/IT1173135B/it active
  • 1984-01-25 GR GR73617A patent/GR81664B/el unknown
  • 1984-01-25 WO PCT/GB1984/000020 patent/WO1984002875A1/en active Application Filing
  • 1984-01-25 CH CH4593/84A patent/CH665488A5/fr not_active IP Right Cessation
  • 1984-01-25 PT PT78009A patent/PT78009B/pt not_active IP Right Cessation
  • 1984-01-26 ES ES529203A patent/ES8501536A1/es not_active Expired
  • 1984-01-26 FR FR8401191A patent/FR2539881B1/fr not_active Expired
  • 1984-01-26 BE BE0/212284A patent/BE898767A/fr not_active IP Right Cessation
  • 1984-01-30 PH PH30173A patent/PH23007A/en unknown
  • 1984-09-21 NO NO843782A patent/NO843782L/no unknown
  • 1984-09-25 DK DK458684A patent/DK161754C/da not_active IP Right Cessation
• 1985
  • 1985-02-25 SE SE8500918A patent/SE453737B/sv not_active IP Right Cessation

Patent Citations (8)

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