Sulfur-containing urethane-based resin and composition and process for producing the resin
AssigneeMitsui Chemicals, Inc.
InventorsKoju Okazaki, Yoshinobu Kanemura, Teruyuki Nagata
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Abstract
A polythiol having four or more functional groups, a process for producing the polythiol comprising reacting thiourea with a specific compound, a sulfur-containing urethane-based resin prepared from the polythiol and a lens made of the resin. The resin has a high refractive index, and low dispersion of refractive index, is lightweight, colorless and transparent, has no optical distortion, and has excellent characteristics in weatherability, dye-affinity, heat resistance, impact resistance and machinability.
Claims19
A sulfur-containing urethane-based resin composition comprising a polythiol having four or more functional groups and at least one isocyanate selected from the group consisting of polyisocyanate compounds, polyisothiocyanate compounds and isocyanato group-containing polyisothiocyanate compounds, said polythiol being represented by any of the following formula (1):
- wherein R1, R2, R3 and R4 are each selected from the group consisting of H, --CH.sub.2 SH, --CH.sub.2 SCH.sub.2 CH.sub.2 SH, ##STR65## provided that where any one of R1, R2, R3 and R4 is H, at least one of the other three radicals represents ##STR66## where any two of R1, R2, R3 and R4 are H, two others are independently selected from ##STR67## and any three or all of R1, R2, R3 and R4 are not H simultaneously;
- formula (2):
- (HSCH.sub.2).sub.4-m C(CH.sub.2 SCH.sub.2 CH.sub.2 SH).sub.m( 2)
- wherein m denotes an integer of 1 to 3;
- and formula (3):
- ##STR68## wherein n denotes an integer of 0 to 3.
Dependencies are inferred from the claim text.