A. Low density: due to the gap between the molecular chains, the number of molecules per unit volume is small, which determines the advantages of the resin lens: low specific gravity and light texture, which is 1/3-1/2 of the glass lens;
B. Moderate refractive index: ordinary CR-39 propylene diethylene glycol carbonate, refractive index is 1.497-1.504. Currently, the highest refractive index of resin lenses sold on the Shenyang glasses market is aspherical ultra-thin hardened film resin lens, refraction The rate can reach 1.67, and there are now resin lenses with a refractive index of 1.74.
C. The surface hardness is lower than that of glass, and it is easy to be scratched by hard objects. Therefore, it needs to be hardened. The hardened material is silica, but the hardness is not as good as the hardness of the glass. Therefore, the wearer should pay attention to the lens. maintenance;
D. The elasticity is good. Due to the space between the organic molecular chains, the elasticity is 23-28 times that of the glass piece. Another major characteristic of the resin sheet is determined – good impact resistance. European, American, and Japanese countries prohibit children under the age of 16 from wearing glass lenses;
E. Auxiliary function: It can be added to obtain functions such as preventing harmful rays and discoloration.
Post time: Apr-01-2005