IES950645A2 - Lens coating process - Google Patents

Lens coating process

Info

Publication number
IES950645A2
IES950645A2 IES950645A IES950645A2 IE S950645 A2 IES950645 A2 IE S950645A2 IE S950645 A IES950645 A IE S950645A IE S950645 A2 IES950645 A2 IE S950645A2
Authority
IE
Ireland
Prior art keywords
lens
blocking agent
coating
ultraviolet light
spectacle
Prior art date
Application number
Inventor
Niall Patrick Mccrudden
Graham Smithers
Original Assignee
Niall Patrick Mccrudden
Graham Smithers
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Niall Patrick Mccrudden, Graham Smithers filed Critical Niall Patrick Mccrudden
Priority to IES950645 priority Critical patent/IES66811B2/en
Publication of IES950645A2 publication Critical patent/IES950645A2/en
Publication of IES66811B2 publication Critical patent/IES66811B2/en
Priority to GB9602671A priority patent/GB2304922A/en
Priority to IE960597A priority patent/IE79048B1/en

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/20Filters
    • G02B5/22Absorbing filters
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G02B1/041Lenses
    • GPHYSICS
    • G02OPTICS
    • G02CSPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
    • G02C7/00Optical parts
    • G02C7/10Filters, e.g. for facilitating adaptation of the eyes to the dark; Sunglasses
    • G02C7/108Colouring materials

Abstract

A lens, such as a spectacle lens, has an ultraviolet light (UV) blocking agent coated on it by a process involving cleaning the lens by immersing it in neutralising solution to clean the lens and to apply a positive charge to it, then bathing the lens in a bath containing UV blocking agent, a heat transferring solution and de-ionised water at between 90°C to 100°C, followed by dipping the lens in methylated spirits. The lens is preferably chamfered prior to treatment so that the edges define a smooth curve. After treatment, the spectacle lens is mounted in a frame and sprayed with an anti-static substance. Lenses coated by the process described display UV transmittance of 0% at 400 nm or longer UV wavelengths.

Description

The present invention relates to a process for coating optical lenses and in particular to a process for coating spectacle lenses.
Spectacle lenses are generally obtained by an optometrist from a supplier and are cut and matched to fit a patient's spectacle frames by a technician in the optometrist's own workshop. Various coatings are routinely applied to the lenses at* this stage. For example, tint may be applied to control the colour of the lens or to adjust the light transmission properties of the lens.
Ultraviolet (UV) light is known to cause damage to the eyes and consequently, it is not uncommon for a spectacle lens prescription to include a requirement for a ultraviolet filter coating to be applied to the lenses.
. At present, there are many different UV blocking dyes on the market. Essentially these fall into three main groups, namely high risk (500-550nm), medium risk (400-500nm) and low risk (350-400nm).
Whilst the availability of standard dyes ensures that workshops can offer ultraviolet protective lens coatings to patients, ho proper standardised technique for handling and preparing the lenses before and after the treatment exists. This is because at present, the UV dye is simply used like a tint, whereby the lens is left in solution for a set time, until the required colour develops.
As mentioned previously, it is generally regarded in medjnal. circl pq gh-t 3 n high doses can or will be j tc r -Γ W^pRT'lON ! j JV'tiM ! — SECTION 28 AND RULE 23 JNL NO»^ OF ^2^ J «τ ajingpi N'g 950645 - 2 harmful to the eyes over a period of time. The eyes, like the skin, have natural protective mechanisms that provide a degree of protection in normal everyday situations from the sun's UV rays. However, in view of environmental concerns, such as the reported depletion of the atmospheric ozone layer which shields the earth's surface from a deal of incident UV rays, and in view of the lack of data on the affect of long-term UV exposure on the eyes, it is desirable to apply UV protection to all spectacle lenses, whether prescription or otherwise.
Accordingly, the present invention provides a process for coating optical lenses with an ultraviolet light (UV) blocking agent, comprising:cleaning a lens by immersing it in a neutralising solution containing an ionizing agent for a period sufficient to ensure that the surface of the lens is free of impurities and has a positive charge; bathing the lens in a tinting bath containing a heat transferring fluid and a UV blocking agent dispersed in de-ionised water and heated to between 90°C and 100°C, for a time sufficient to allow the blocking agent to be absorbed on to the lens surface; and thereafter dipping the treated lens in a volatile organic alcohol to clean and degrease the lens surface.
Usually, the lens will be immersed in the neutralising solution for at least ten minutes.
Preferably, the lens is chamfered prior to coating to give 950645 - 3 its edges a curved smooth edge.
Conveniently, the tinting bath is heated to 97°C +/- 2°C and the volatile organic alcohol is methylated spirits.
Advantageously, the lens is a spectacle lens and the process includes mounting the lens in a spectacle frame after coating and optionally, spraying the mounted lens with an anti-static agent.
The invention also provides a lens coated with a UV blocking agent whenever prepared by the process as herein described.
Normally, once a lens has been cut, it is put into a special wheel to chamfer the edges. This is to ensure that it fits correctly into the frame. According to the invention described herein, this procedure is extended so that each lens has a rolling edge. This means that the lens itself exhibits a fine curved smooth edge instead of a harsh angular one. The benefit of this in the UV coating process of the invention is that the solution will have a completely even adherence, uniform in its thickness throughout the lens. An angular chamfer often leads to irregularity at the edges, which in turn can lessen the optical performance of the lens.
The next step is systematically to clean the lens in neutralizing solution. One suitable neutralising solution is diethylene glycol monoethyl ether, supplied by B.P.I. International. At least ten minutes immersion is required to ensure that the lens surface is completely devoid of any impurities. In prior art processes a mere wash in tap water was conducted prior to UV coating. The neutralising solution surrounds the lens in an ionizing agent that . 95 0 6 4 5 leaves a positive charge on the lens surface, ensuring even adherence of UV dye and a non-greasy surface. The lenses are laid on racks submerged in the neutralising solution for at least 10 minutes. For thicker lenses, a longer immersion is required to ensure the adequate treatment of the lens.
Once this procedure is complete, the lenses are ready for the UV dye treatment, which is performed by bathing the lens in an appropriate UV dye solution until such time as the desired degree of dye is absorbed onto the lens surface. The tinting bath contains an aqueous solution of the UV dye (usually anthraquinone derivatives and/or azodyes) and includes a heat transferring fluid such as B.P.I. International's HTF 90. Glycerine based heat transferring fluids may also be used, but are less satisfactory due to the generation of toxic fumes. The water used in the bath is de-ionised water rather than tap water as the letter can contain impurities which have an adverse effect on the coating process. The bath is heated to assist in effective transfer of dye on to the lenses in the bath. Suitably, the bath is heated to between 90 and 100°C, preferably 97°C. The heat transferring fluid ensures that the tint stays at a fixed temperature and that no hot-spots develop in the tinting dyes which could cause uneven lens coating.
Stage three of the procedure is done after the lens is removed from the UV treatment bath. At this point in the prior known process, the lens would normally be washed again in tap water and then mounted into the spectacle frame. According to the present process, the lens is first dipped into a solution of methylated spirits for 10 seconds, then dried. The treatment with methylated spirits serves to remove any impurities from the surface 950645 - 5 of the lens by degreasing and removing any surface deposits such as marking inks. Any non-toxic volatile organic alcohol could be used in place of methylated spirits and this treatment also serves to add a key for the next step in the process so as to ensure that a uniform surface is ultimately obtained. Next, the lens is mounted into the frame, then finally sprayed with an anti-static spray such as Calotherm (trade mark) spray, Norville Optical, to keep the lens dust free. By way of quality control, the mounted lens is put under the spectrometer for its final testing of the UV blocking properties. The UV transmission required from the coated lens is 0% transmission at 400 nm or longer UV wavelengths. The blocking obtained is a function of the particular dye chosen and the length of time that the lens if left in the tinting bath.
The process according to the invention is a carefully controlled one from start to finish to ensure that the optical qualities of the coated lens are as perfect as possible. Such quality control is not achievable in the prior known lens coating processes.
By the use of the process described herein, the optometrist can guarantee that the coating has been evenly applied to a lens that has no irregularities or imperfections, thereby ensuring maximum protection for the user.
It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

Claims (5)

1. A process for coating optical lenses with an ultraviolet light (UV) blocking agent, comprising:cleaning a lens by immersing it in a neutralising solution containing an ionizing agent for a period sufficient to ensure that the surface of the lens is free of impurities and has a positive charge; bathing the lens in a tinting bath containing a heat transferring fluid and a UV blocking agent dispersed in de-ionised water and heated to between 90°C and 100°C, for a time sufficient to allow the blocking agent to be absorbed on to the lens surface; and thereafter dipping the treated lens in a volatile organic alcohol to clean and degrease the lens surface.
2. A process according to Claim 1, including chamfering the lens prior to coating to give its edges a curved smooth surface and optionally in which the tinting bath is heated to 97°C +/- 2°C and the volatile organic alcohol is methylated spirits.
3. A process according to any preceding claim, in which the lens is a spectacle lens and the process includes mounting the lens in a spectacle frame after coating and optionally, spraying the mounted lens with an anti-static agent.
4. A lens coated with an ultraviolet light blocking agent whenever prepared by a process according to any of the preceding claims. 950645
5. A process for coating optical lenses with an ultraviolet light blocking agent according to any of Claims 1 to 3, or a lens according to Claim 4, 5 substantially as herein described.
IES950645 1995-08-24 1995-08-24 Lens coating process IES66811B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
IES950645 IES66811B2 (en) 1995-08-24 1995-08-24 Lens coating process
GB9602671A GB2304922A (en) 1995-08-24 1996-02-09 Coating lens with ultraviolet blocking agent
IE960597A IE79048B1 (en) 1995-08-24 1996-08-21 Lens coating process

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IES950645 IES66811B2 (en) 1995-08-24 1995-08-24 Lens coating process

Publications (2)

Publication Number Publication Date
IES950645A2 true IES950645A2 (en) 1996-02-07
IES66811B2 IES66811B2 (en) 1996-02-07

Family

ID=11040858

Family Applications (1)

Application Number Title Priority Date Filing Date
IES950645 IES66811B2 (en) 1995-08-24 1995-08-24 Lens coating process

Country Status (2)

Country Link
GB (1) GB2304922A (en)
IE (1) IES66811B2 (en)

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5298033A (en) * 1989-03-14 1994-03-29 Ciba-Geigy Corporation Ultraviolet absorbing lenses and methods of manufacturing thereof

Also Published As

Publication number Publication date
GB9602671D0 (en) 1996-04-10
GB2304922A (en) 1997-03-26
IES66811B2 (en) 1996-02-07

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