US 5,679,756 A · Optical thermoplastic thiourethane-urethane copolymers

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.

Claims31

Dependent claims

A method for the preparation of optical thermoplastic thiourethane-urethane polymers comprising:

reacting a monomer composition comprising an organic polyisocyanate and a monomer having at least two groups reactive with the isocyanate component under polymerization conditions to form a thiourethane prepolymer having reactive endgroups with the molar ratio of isocyanate group to reactive group about 0.5:1 to 3:1;
reacting the prepolymer under polymerization conditions with polyurethane forming monomers comprising an organic polyisocyanate and a monomer having at least two groups reactive with the isocyanate group to form the optical polymer product with the molar ratio of isocyanate groups used to form the prepolymer and the polymer product to the total reactive groups used to form the prepolymer and the polymer product being about 0.9:1 to 1.1:1.

Dependencies are inferred from the claim text.

Optical thermoplastic thiourethane-urethane copolymers

Life of this patent

Optical thermoplastic thiourethane-urethane copolymers

Life of this patent

Abstract

Claims31