Zhou Rong Yang

US Patent:

56797567, Oct 21, 1997

Filed:

Dec 22, 1995

Appl. No.:

8/548806

Inventors:

Zhenya Zhu - Stratford CT
Brian G. Risch - Milford CT
Zhou Yang - Milford CT
Yin-Nian Lin - Milford CT

Assignee:

Optima Inc. - Stratford CT

International Classification:

C08G 1810

US Classification:

528 65

Abstract:

A process for making thermoplastic thiourethane-urethane copolymers for use in making optical products preferably comprising reacting an aliphatic diisocyanate with a dithiol under polymerization conditions to form a thiourethane prepolymer which is then reacted with a diisocyanate such as methylene bis(phenyl isocyanate) and a polyol such as a diaromatic containing diol such as ethoxylated Bisphenol A or an aliphatic isocyanate reactive monomer such as tricyclodecane dimethanol or 1,4-dimethanol cyclohexane to form the copolymer product. The polymers have a combination of high refractive index and high Abbe No. The polymers also have high impact strength, high hardness and Tg's above 100. degree. C. It is preferred to make the polymer in an extruder.