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

A method for imparting ultraviolet absorbency and/or increasing refractive index to a matrix, comprising combining the matrix with an additive represented by the following Formula (I):

• wherein:
• R1a, R2a, R3a, R4a, and R5a each independently represent a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a hydroxyl group, wherein at least one of R1a, R2a, R3a, R4a, and R5a represents a methyl group;
• R6a, R7a, R8a and R9a each represent a sulfur-containing monovalent group represented by the following Formula (i-2) or a hydrogen atom, wherein at least one of R6a, R7a, R8a and R9a represents the sulfur-containing monovalent group of Formula (i-2):
• n and p each represent 0;
• R13a represents a reactive functional group selected from the group consisting of a hydrocarbon group substituted with a hydroxyl group, a hydrocarbon group substituted with a thiol group, a hydrocarbon group substituted with a carboxyl group, a hydrocarbon group substituted with an amino group, a hydrocarbon group substituted with a silyl group, and a group containing a carbon-carbon double bond, wherein the group containing a carbon-carbon double bond is selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a maleoyl group and a styryl group, and wherein each hydrocarbon is that in which a proximal terminal carbon is optionally interrupted by, a hydrogen atom is optionally substituted with, or a carbon-carbon bond is optionally interrupted by a monovalent or divalent group selected from the group consisting of 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
• wherein:
• the matrix is transparent;
• and
• the additive represented by the Formula (I) has a light absorption peak present in a wavelength range of 350 to 390 nm in a 100 μM chloroform solution, the absorption peak present in the wavelength range is a maximum absorption wavelength (λmax), and a gradient at a longer wavelength side of the absorption peak is 0.025 or more, wherein the gradient of a straight line is connected between an absorption peak and a peak end of an absorption spectrum at the longer wavelength side of the absorption peak.