What material are the resin lenses in glasses made of?
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I recently got a pair of glasses with resin lenses; they are much lighter than glass or crystal lenses, but they are still quite expensive. I would like to ask everyone: what material are the resin lenses in glasses made of? Thanks for the advice.
It is usually made of PC or acrylic, with a surface hardening treatment.
Currently, cellulose triacetate resin is used for lenses; it is said that PC is also used. Japan has now developed a cycloolefin polymer optical material for lenses, which is said to have excellent light transmittance and hardness.
There are mainly three types of resins. 1. Polymethyl methacrylate: Its trade name is PMMA; it is also known as Acryl. Refractive index 1.49, dispersion 58, specific gravity 1.19. Advantages: Light weight, 1/2 that of glass. Good impact resistance, safe. Disadvantages: It is a thermoplastic material with a solubility of 75°C; it deforms easily when heated, resulting in changes in refractive power. The surface hardness is insufficient, resulting in poor wear resistance. II. Allyl digluycel carbonate, also known as allyl ethylene glycol carbonate; its trade names are Colungia resin and CR-39. It is an extract derived from petroleum. Refractive index 1.4985, Abb number 57.8, specific gravity 1.32. Advantages: Light weight, safe, and highly impact-resistant. Ultraviolet-resistant; it can block all ultraviolet rays with a wavelength of 350mm or less. Easy to dye Modern casting processes enable mass production. Disadvantage: Poor wear resistance. A lower refractive index makes the lens appear thicker. III. PC (Polycarbonate) is a polymer formed by the polymerization of flexible carbonate rings and inflexible bisphenol A. The molecular weight is between 20,000 and 38,000, and the refractive index at 25°C is 1.586. Lenses made from this material are called “space lenses”. Advantages: Light – 57% lighter than traditional glass sheets; Safe – its impact resistance is 60 times that of glass, and it can be used as bulletproof glass at a thickness of 2.5 cm. It is thin, with the same thickness as CR-39 lenses having a refractive index of 1.6. Disadvantage: Poor wear resistance.
Resins for Optical Lens – this is currently produced in China by Aokeli