Patent ID: 9333716
Filing Date: 2016-05-10
CPC Classification: B29C,B29D,B29K

Claim Text:
1. An improved method of cast molding contact lenses, wherein a lens forming material is cured in a lens-shaped cavity formed between molding surfaces of a male and female mold sections, wherein the improvement comprises injection molding at least one of mold sections from a controlled rheology polypropylene, wherein the controlled rheology polypropylene has a higher melt flow rate of at least about 6 g/10 minutes than that of a corresponding pristine polyprolylene, wherein the corresponding pristine polypropylene is a starting polypropylene prior to going through a controlled rheology process, wherein the controlled rheology polypropylene has a melt flow rate of from 12 g/10 minutes to 80 g/10 minutes, wherein the controlled rheology polypropylene having a tangent delta of at least about 5 at 1 rad/second provides the mold section with a less mold warpage, compared to a mold material having the corresponding pristine polypropylene having the same melt flow rate.