Study On Photochromic Flexible Coating Of Resin Lens Surface

With the development of society,ozone layer is largely destroyed.The ultraviolet(UV)radiation that should have been absorbed by ozone layer in sunshine comes to the ground.It produces great harm to our eyes and skin.Because of popularization of mobile phones and computers,people's excessive use of eyes has become a universal problem.The blue and violet light on mobile phones and computer screens are particularly harmful to human eyes due to their high energies.Long-term exposure to UV and blue light is likely to lead to early cataract,and damage retinal pigment epithelial cells directly and accelerates senile macular degeneration.Therefore,the concept of using UV-proof sunglasses to protect eyes has been widely accepted by consumers.Photochromic lenses can effectively protect eyes from being stimulated in strong light,and can filter the UV light from sunlight.Therefore,photochromic lenses have great potential market and commercial prospects.This paper first analyzed the photochromic mechanism of dye.And it determined that our goal wass to prepare polymers with good molecular flexibility.Using isophorone diisocyanate trimer(t IPDI)and hydroxyl acrylate and polyhexane carbonate glycol as the main raw materials,we synthesized polyurethane coatings with molecular flexible.The film was characterized by infrared spectrum(FTIR),UV-visible spectrum,DSC and the fading rate test.The photochromic dyes doped in the polyurethane film changed color and bleached quickly.It fully proved the good molecular flexibility of the polyurethane film.However,due to the dye damaging by UV light and free radical in the process of UV curing,the color of the coatings became yellow after UV curing.It was detrimental to the commercial use of the photocromic coatings.Knowing the reason of the film yellowing,we planed to solve this problem with microcapsules sustained releasing.Polyurea microcapsules with particle size of 250-500 nm were designed and synthesized.The wall materials were synthesized by interfacial polymerization of isoflurone diisocyanate trimer(t IPDI)and triethylene tetramine(TETA).In addition,we characterized the microcapsules with SEM,FTIR,TGA,DSC.FTIR confirmed the dye microcapsules capsule wall components.Thermal analysis confirmed that microcapsules under 280 ? would keep thermal stability well,and the Tg of microcapsules wall was 120 ?.Then we tested the extraction of dyes inside microcapsules in different solvents and determined the embedding rate(54%).Finally,the thermal releasing of dye in TMPTA resin was tested,and the dye was released into TMPTA resin after heating.After synthesizing polyurea microcapsules containing photochromic dye,we dispersed the microcapsules in the prepolymer(PUA-OH).And PUA-OH was coated on the propylene diglycol carbonate(CR-39)blank lenses to prepare the photochromic coatings by UV curing.In the end,the coating was fuzzy in the end,because the microcapsules could not be dispersed in PUA-OH.We used grinding,stirring,ultrasound,high-speed homogenization and other methods,but still failed.This work prepared photochromic coating for lenses,but did not solve the problem of dye damaging completely.It has some reference for preparing photochromic coatings and dye protection in UV curing.