Additive for imparting ultraviolet absorbency and/or high refractive index to matrix, and resin member using same

An additive represented by the following formula (III):

• wherein R1c to R10c each independently represent a monovalent group selected from a monovalent sulfur-containing group represented by the following formula (iii-1) or formula (iii-2), a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an aromatic group, an unsaturated group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group, and a halogen atom:
• wherein in the formula (iii-1), R11c represents a divalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with, interrupted at least any one of two terminals by or interrupted a carbon-carbon bond by a monovalent or divalent group selected from an aromatic group, an unsaturated group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom;
• and t represents an integer of 0 or 1, and
• in the formula (iii-2), R12c represents a divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted with, interrupted at least any one of two terminals by or interrupted a carbon-carbon bond by a monovalent or divalent group selected from an aromatic group, an unsaturated group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom;
• R13c represents, or if v is 2 or larger, R13c's each independently represent, a divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted with, interrupted at least any one of two terminals by or interrupted a carbon-carbon bond by a monovalent or divalent group selected from an aromatic group, an unsaturated group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom;
• R14c represents a monovalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted with, interrupted a proximal terminal by or interrupted a carbon-carbon bond by a monovalent or divalent group selected from an aromatic group, an unsaturated group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom;
• the total number of carbon atoms of R12c, v units of R13c and R14c is 25 or less;
• u represents an integer of 0 or 1;
• and v represents an integer from 0 to 3,
• with the proviso that at least one of R1c to R10c is a monovalent sulfur-containing group represented by the formula (iii-1) or formula (iii-2).