Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-09-22
2001-02-13
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C264S001100, C264S002300, C264S002600, C264S334000, C425S808000, C526S194000, C526S209000, C526S319000, C526S344000
Reexamination Certificate
active
06187888
ABSTRACT:
1. Field of the Invention
The present invention relates to a cast-molding material for a plastic lens and a process for the production of a plastic lens. More specifically, it relates to a cast-molding material for a plastic lens which is free from causing defective dyeing when dyed, and a process for producing plastic lenses from the material at high yields.
2. Prior Art
Plastic lenses obtained by cast-molding diethylene glycol bisallylcarbonate (called “DAC” for short hereinafter) have been and are widely used as various optical lenses such as ophthalmic lenses. That is because lenses formed of DAC resin have remarkably excellent performances, e.g., that they have a light weight and are not easily breakable as compared with glass, and that they can be dyed.
The cast-molding of DAC generally uses a mold formed of glass, gaskets of a resin and an adhesive tape, and it is known that the cast-molding also uses a mold releasing agent, e.g., Zelec UN(trade name, supplied by E. I. du Pont de Nemours & Co.) or butyl stearate (data to “HIRI CASTING RESIN”, issued by PPG, 1996). The effect of the use of the mold releasing agent is that the releasability of lenses from a mold is improved so that an improvement in workability and the prevention of breaking of lenses are attained.
When lenses are produced from DAC resin, however, lenses having some forms incur an undesirable outcome of a distinctive non-uniformity of dyeing when dyed, as shown in FIG.
1
. This phenomenon is outstanding in plus power number (including 0.00 diopter (D)) lenses having a meniscus form and having a smaller radius of curvature of a convex surface than the radius of curvature of a concave surface. The above defect is found only after lenses are dyed, and it is therefore a major factor for decreasing the acceptance ratio of lenses in the step of dyeing.
For overcoming the above problem, the present inventors have made diligent studies and have arrived at the present invention by finding the following. A material containing, as essential components, a combination of either DAC or a mixture of DAC and a monomer copolymerizable therewith with a specific silicone compound can overcome the above problem, and plastic lenses almost free from causing defective dyeing can be obtained at high yields by cast-molding the above material in a mold.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a cast-molding material for a plastic lens which is almost free from causing defective dyeing when dyed, and a process for producing plastic lenses almost free from causing defective dyeing at high yields.
According to the present invention, there is provided a cast-molding material containing, as essential components, a combination of (A) DAC or a mixture of DAC and a monomer copolymerizable therewith, with (B) a polyether-modified silicone compound.
Further, according to the present invention, there is provided a process for the production of a plastic lens, which comprises cast-molding the above cast-molding material in a mold.
Further, in a preferred embodiment of the process of the present invention, a cast-molding material containing the above component (A) and 0.1 to 10,000 ppm by weight, based on the component (A), of the component (B) is cast-molded in a mold, or the interior surface of a mold is pre-treated by coating it with the component (B) and then the component (A) is cast-molded in the mold.
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Kageyama Yukio
Nakamura Shigeo
Shimizu Akiko
Burns Doane Swecker & Mathis L.L.P.
Cooney Jr. John M.
Hoya Corporation
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