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| CR-39 | |
|---|---|
| Name | CR-39 |
| Other names | allyl diglycol carbonate |
| Formula | C12H18O7 |
| Molar mass | 274.27 g·mol−1 |
| Appearance | colorless solid |
CR-39 CR-39 is a trade name for a polymer widely used in optical lenses and radiation dosimetry. It is an allylic polyester formed by polymerization of allyl diglycol carbonate, notable for its combination of low density, high optical clarity, and abrasion resistance compared with glass and competing plastics. Major manufacturers, opticians, and research laboratories have applied CR-39 across ophthalmic, photographic, and scientific fields.
CR-39 is chemically allyl diglycol carbonate, produced by thermally initiated free-radical polymerization of allyl monomers in the presence of crosslinking agents and inhibitors. Production processes developed in industrial settings at companies like PPG Industries and Corning use molds and controlled curing ovens similar to techniques used in polymerization of polymethyl methacrylate at facilities operated by Eastman Chemical Company and DuPont. Chemical engineering protocols reference catalysts and inhibitors studied at institutions such as the Massachusetts Institute of Technology, Stanford University, and the University of Cambridge. Patent filings by inventors associated with companies including PPG and Rohm and Haas outline compounding formulations and post-curing stabilization steps performed in plants in the United States, Germany, and Japan.
CR-39 exhibits a refractive index around 1.498 and an Abbe number comparable to mid-index optical plastics used by lens manufacturers such as Essilor, Zeiss, and Hoya. Its density is lower than crown glass produced by Saint-Gobain and Schott, giving weight advantages used by eyewear brands like Luxottica and Safilo. Optical tests performed at laboratories in the National Institute of Standards and Technology and the Optical Society of America show good transmission across the visible spectrum, with UV absorption properties similar to certain formulations of polycarbonate produced by Sabic and Bayer. Mechanical characterizations by researchers at Imperial College London and the University of Tokyo report Young's modulus and impact resistance values that sit between polycarbonate and acrylic counterparts used by 3M and BASF.
CR-39 is primarily used for ophthalmic lenses sold by retailers such as LensCrafters, Vision Express, and Walmart Optical, and for safety eyewear certified under standards promulgated by ANSI and ISO committees. It has been used in camera lens elements by manufacturers like Nikon and Canon, and in scientific detectors for dosimetry in facilities including CERN and Fermilab. Photographic and cinematography suppliers such as Kodak and Panavision have evaluated CR-39 for specialty filters. Aerospace and defense contractors, including Lockheed Martin and Boeing, have assessed CR-39 for non-structural transparent components tested against specifications from NASA and the U.S. Department of Defense.
CR-39 resists scratches better than many polycarbonate grades sold by GE and Samsung, though it is less impact-resistant than polycarbonate used by Honeywell for ballistic glazing. Weathering studies by agencies such as the Environmental Protection Agency and the European Chemicals Agency document yellowing mechanisms under UV exposure akin to those seen in polymethyl methacrylate researched at the University of California, Berkeley. Chemical compatibility tests performed at laboratories affiliated with the American Chemical Society and RIKEN outline solvent sensitivities similar to acetone and methyl ethyl ketone handled in industrial hygiene practices at OSHA-regulated sites. Toxicology assessments referencing WHO and FDA guidance indicate that properly polymerized CR-39 poses low leaching risks in eyewear applications commonly marketed by optical chains like Pearle Vision.
The resin was developed mid-20th century by researchers linked to PPG Industries and introduced commercially in ophthalmic markets alongside innovations from Zeiss and Bausch & Lomb. Early polymer chemistry work at institutions such as the University of Illinois and the Swiss Federal Institute of Technology (ETH Zurich) informed monomer synthesis and curing processes. The trade name and commercial adoption followed patent activity in the 1940s–1960s during the postwar expansion of plastics industries involving firms like DuPont and Rohm and Haas.
The ophthalmic lens market features CR-39 alongside alternatives such as polycarbonate, Trivex, and high-index glass from manufacturers like Schott, Hoya, and EssilorLuxottica. Global production takes place in countries with major chemical industries including the United States, Germany, Japan, and China at plants operated by multinational corporations such as PPG and Lanxess. Market analysis by firms like McKinsey and Bain highlights competition from injection-molded polycarbonate supplied by Sabic and recycled acrylics marketed by Covestro. Ongoing research at universities including MIT and Tsinghua explores biodegradable and higher-refractive-index alternatives for future optical applications.
Category:Polymers