A versatile plastic for glasses


PHOTO: For its corrective and sunglass lenses, Chinese OEM Jiangsu Sigo Optical uses optical polycarbonates from Covestro since they offer improved optical purity and production yield, compared to other materials


POLYCARBONATE is an ideal lens material for corrective eyeglasses and sunglasses: It is lightweight, impact resistant, durable and comfortable. However, not all polycarbonate for eyewear applications is created equal. Covestro has developed special lens-quality grades of its Makrolon® polycarbonate which are characterized by excellent optical properties, high mechanical strength, toughness and comfort.

When original equipment manufacturer Jiangsu Sigo Optical Co decided to upgrade the polycarbonate material used for its corrective and sunglass lenses, it turned to Covestro Makrolon polycarbonate resins for improved optical purity and production yield.

For corrective lenses, Jiangsu Sigo Optical uses Makrolon DP1-1821 polycarbonate, which is formulated specifically for the ophthalmic market. Available in clear tints, the material offers a number of advantages for corrective lenses including high optical purity, transmission and scatter resistance and UV stabilization. In processing, the material is distinguished by its high viscosity and easy release from the mold.

For outdoor activities, sunglasses provide UV protection, impact-resistance and style. Makrolon LQ2887 polycarbonate, a new optical grade, is used for high-performance sunglass lenses from Jiangsu Sigo Optical.

Importantly, Makrolon LQ2887 polycarbonate provides UV protection from wavelengths up to 400 nanometers (nm), which blocks both energy-rich UVA and UVB rays. The product offers thin and fashionable, yet impact resistant lenses, and is appropriate for outdoor sports such as mountain biking and beach volleyball. UV protection is especially effective in beach and snow environments where water and snow strongly reflect harmful UV rays.