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Chemical Nano Technology ~ General Information on Scratch Resistant Treatments ~ Updated 05/03/2008

SCRATCH RESISTANT TREATMENTS ON OPTICAL SURFACES

 Definition of a Hard Coat on optical lenses:  

A layer of material that is harder than the basic material (substrate) . The hard coat material is chemically bonded to the substrate and its hardness is limited to the flexibility of the basic lens material. (crazing, delaminating) 

Resulting effect on a Hard Coated lens: 

As the applied layer is harder than the basic surface it has been established that with a Taber test, pencil test or a haze test (generally accepted testing methods) the added layer of harder material took longer to be damaged in those test’s than the basic material. 

OMS started in the hard coat business in 1982 by developing a thermo cure (curing by heat) polysiloxane coating material that was widely used on the optical market in the 1980’s. In 1985 OMS was the second company worldwide to develop and have a UV curable polyester or vinyl coating resin (instant cure by UV radiation).

In order to use these products, expensive machinery is required to apply the materials properly to the lens surfaces. A retail business could not afford to operate one of these coating machines for use in small volumes only.

Definition of a Slick Coat:  

This treatment consist of the application of a polysiloxane polymer or teflon layer on the substrate. These materials do NOT provide a so called hard coat. (therefore conventional pencil and haze test’s are invalid and do not apply)) 

These products provide a very thin ULTRA SLICK surface. A surface treated with these materials will let objects slide off the surface instead of hooking on and scratching the surface. If an anti-stat agent is added to the material, the surface will not accept static charges and therefore dust will not cling to it and lenses stay clean much longer. As an other additional benefit anti-fog agents can also be added to speed up and dissipate fogging up of the surface.

HISTORY OF SCRATCH RESISTANT TREATMENTS

Retailers demanded a scratch resistant system for use on lenses that was easy to apply without machinery. OMS introduced the first of the slick coat systems with the SCRATCH GUARD treatment in 1985. This is a poly siloxane treatment which provides a super slick surface. aS A CR39 lens  is very porous IT is soaked in the solution and then heated in a convection laboratory oven at 110 C for 20 Minutes to let the pores open up and let the siloxane penetrate into the surface. Once it is cooled off and the pores are closed up the surface results in a ultra slippery condition. In a newer version this product can now be heated in a microwave oven for one minute. 

In 1990 OMS introduced a cold application that could be done by just dipping the substrate into the liquid for one second only. The product is called SUPER SCRATCH GUARD. Annual sales of this product treat 45 Million pairs of lenses on yearly basis. 

CAUTION

Slick coats should never be used on un- coated High Index and Polycarbonate lenses as the base material of these lenses is  very soft and they must be hard coated to give them the proper protection.

OMS SCRATCH RESISTANT TREATMENTS

Click:

1)    Scratch Guard                   including anti-stat and anti-fog     (soak and heat)

2)    Super Scratch Guard     including anti-stat and anti-fog  (dip for one second at room temperature, wipe dry) , for a double layer can be dipped 2x.     

3)    MICRO-SCRATCH GUARD        including anti-stat and anti-fog (soak for 15 minutes and heat in microwave oven for 2 minutes)

4)    Dip and Dry scratch resistant treatment   including anti-stat and anti-fog   (dip at room temperature, remove and dry)

5)   OPL-UV                                  UV curable hard coat non tint able or tint able

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