Abstract: An ultraviolet absorbent substance includes a metal complex and a matrix, formed with at least one matrix material and/or polymerizable monomer as a precursor of a matrix material and containing said metal complex therein. One exemplary function of the ultraviolet absorbent substance is allowing visible light rays transmitted through satisfactorily while selectively blocking ultraviolet rays.

Abstract: A composition for an ultraviolet absorbent substance which comprises at least one metal complex represented by formula (1) and at least one matrix material and/or polymerizable monomer as a precursor of a matrix material, and an ultraviolet absorbent substance comprising the composition: wherein Y1, Y2, Y3 and Y4 are each, independently of one another, NH, NR5, an oxygen atom or a sulfur atom, and R5 of NR5 assigned to Y1, Y2, Y3 or Y4 is an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 15 carbon atoms, which may have substituent(s).

Abstract: The present invention provides a process for producing a methylene disulfonate compound in a simple manner at low cost. The present invention provides a process for producing a methylene disulfonate compound represented by General Formula (2) comprising: reacting, in the presence of a dehydrating agent, a formaldehyde compound with a sulfonic acid compound represented by General Formula (1): wherein R1 and R2 are independently a hydrogen atom or a C1-4 alkyl group whose hydrogen atom may be substituted with halogen atom; n is an integer from 1 to 4; and when n is an integer from 2 to 4, n R1s and n R2s may be the same or different: wherein, R1, R2, and n are the same as those described above for General Formula (1).

Abstract: The present invention provides a process for producing a methylene disulfonate compound in a simple manner at low cost. The present invention provides a process for producing a methylene disulfonate compound represented by General Formula (2) comprising: reacting, in the presence of a dehydrating agent, a formaldehyde compound with a sulfonic acid compound represented by General Formula (1): wherein R1 and R2 are independently a hydrogen atom or a C1-4 alkyl group whose hydrogen atom may be substituted with halogen atom; n is an integer from 1 to 4; and when n is an integer from 2 to 4, n R1s and n R2s may be the same or different: wherein, R1, R2, and n are the same as those described above for General Formula (1).