Posted in | News | Medical Optics Develops New Color Tint Technology for Sunglasses ("GS"), the online glasses retailer, announced today that a new color tint technology for sunglasses has been successfully developed. The "CR-39 resin lens" means a milestone not only for GS, but also for the whole industry. It sets an extraordinary new benchmark.

The sunglasses resin lens is popular in recent years due to its unique optical advantages of lightness, impact resistance and easy color tint, etc. It filters over 99% of UV and blue light after it's been tinted, thereby making it a good eye protection tool. Medical Eye Care theoretical studies have shown that ordinary sunglasses cannot protect eyes in an effective way, and are even harmful. They are ultraviolet transparent. The UV light is able to damage the cornea and eyeball, resulting in cases of cataract, inflammation and night blindness.

The CR-39 sunglasses resin lens is manufactured with a special tinting technology which can protect eyes and improve visibility. It is an ideal decorative lens. The resin lens is a kind of macromolecule polymer. It has a good mechanical strength and flexibility and good heat resistance after being molded. The CR-39 Resin Lens has a good "affinity" on hydrophobic pigments. As soon as it is immersed in hot dye liquor, the paint begins to adsorb onto the surface. As the temperature rises, the macromolecular network structure is gradually loosened, making a number of micro-holes. The holes are able to accommodate the pigment molecules.

At the same time, the heat of dyeing liquor dissolves in water increasing the single-molecule's kinetic energy to accelerate its spread to the lens. Meanwhile, at a high temperature, the kinetic energy and the number of activated molecules continue to increase, making the water fill with solubility. A continuous spread of pigment single-molecule into the lens leads the concentration around the lens into reducing. It leads concentration imbalance and becomes the liquor unsaturated solution. However, almost in no time the pigment in distance will be dissolved into single molecules. As molecules are in constant motion, they automatically absorb into the lens and penetrate into it. All of the above is done automatically until the stain in balance, signifying the completion of the staining. The, as the lens is cooling off, the molecules are gradually condensed in the lens and no longer dissolved, thereby obtaining a high color fastness.

  A) Staining Method
       (1) Staining Liquor is made of toner, water and dyeing auxiliary.
           Dyeing auxiliary is used to make the toner better dissolve in water
           and accelerate lens dyeing.  The temperature of staining toner is
           usually in the range of 80-90 degrees Celsius, in line with the
           color required.
       (2) Dyeing principle.  When the lens at a high temperature, the
           molecular space expands to make toner particles move into the space
           within the molecules.  As soon as the lens is cooling, the
           molecular gap will narrow to complete the coloring.  Staining at
           different times makes particles soaked and color depth different.
           The general color depth is 0.03-0.1mm or so.

  B) Operation Process
       (l) The lens must be rinsed to remove the dust and oil stains, using
           alcohol or a washing machine.
       (2) The lens is supposed to be fixed to the dyeing machine rack
           (loading rack), then put into the dyeing machine tank.  Generally,
           it's recommended to use an electric dyeing machine, containing a
           different number of stainless steel tanks with different dye
           staining liquor.  They can be heated independently or
           simultaneously.  There's a thermostat in the stained box to allow
           constant temperature conditions.  The dyeing machine is also
           equipped with a supersonic device.  The duration is set according
           to the concentration of colored lenses.  When time is up, the
           loading rack will eject from the staining liquor.  As soon as it
           ejects, the lens is supposed to be rinsed in order to prevent
           uneven coloring.  At last, the lens and the sample are laid on the
           white paper to compare the color and concentration.

  C) Gradual Dyeing Method
       (1) The color is different within the same lens due to the soaking time
           difference.  The dyeing machine adjusts lens up and down in the
           staining tank to control the time of soaking in order to change the
           color depth.

  D) Notes
       (1) The amount of toner, dyeing auxiliaries and water shall be
       (2) Use ultrasound, alcohol or some other solvents to clean the grease,
           fingerprints, and some other dirt on the lens in order to avoid
           uneven dyeing.

(3) Factors that affect the lens dyeing include the concentration and temperature of dyeing liquor, the duration and the lens' producing span. The material of resin lens now includes AC, PC, CR-39, PET, MR and so on. Due to the material variety, the dyeing liquor and temperature change accordingly. Usually, dyeing auxiliaries include white, yellow and black solutions. The white solution can deepen the color and make the blue look heavier, but it would cause white stripes when over used. The yellow solution is able to make the color lighter but could hardly be dissolved when over used. It would lead to an uneven stain. The black solution can make the color become lighter and browner. It would cause an uneven stain and black stripes if it is over used.

  Reference: White solution: 2500 grams
               Yellow solution: 600 grams
               Black solution: 700 grams
               Toner: 300 grams
               Water: 90 kilograms


Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type