Importance

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Abstract

An improved method for manufacturing spectacle lenses and the like from diglycol allyl carbonate or equivalent plastic by first heating the plastic monomer in the liquid state and containing a polymerization initiator therefor in a planar mold until a degree of polymerization in the range of about 65-85% of completion has been achieved, then removing the partially polymerized material from the mold, subjecting the same to deflection to a curvature corresponding to the desired lens and heating the thus-deflected material until polymerization is complete. Preferably, the initial planar molding step is carried out with a layer or sheet of the material of sufficient size as to contain a plurality of individual lens elements, and after removal thereof from the mold, a plurality of individual lens elements is derived therefrom and such elements are separately subjected to deflection and further polymerization. Preferably, the amount of polymerization initiator exceeds the normally used amount. A post thermal treatment is advantageous to stabilize the lens elements from loss of the curvature imparted thereto.

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First Claim