Light-resistant, heat-resistant and durable ultraviolet absorber

A light-resistant ultraviolet absorber comprising a 2-phenylbenzotriazole derivative that contains a thioaryl ring group or thiocyclohexyl ring group and is represented by any one of the following formulae (1), (3) and (4):

• wherein PhBzT1a represents a 2-phenylbenzotriazole skeleton bonded to a thioaryl ring group (—S—X1a— . . . ), the 2-phenylbenzotriazole skeleton being represented by the following formula (A):
• wherein in the formula (A), R6, R7, R8 and R9 are each independently the thioaryl ring group or a hydrogen atom and at least one of R6, R7, R8 and R9 is the thioaryl ring group, R1, R2, R3, R4 and R5 are each independently a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a hydroxy group, and the thioaryl ring group being such that:
• i) X1a represents a residue of phenyl ring, R1a independently represents a tertiary and/or quaternary carbon-containing alkyl group having 3 to 8 carbon atoms, and l represents an integer of 1,
• ii) X1a represents a residue of phenyl ring, each of l R1as independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, l represents an integer of 2, and a total number of the carbon atoms in these alkyl groups is 2 to 5,
• iii) X1a represents a residue of phenyl ring, each of l R1as independently represents an alkoxy group possessing a linear or branched alkyl group having 1 to 18 carbon atoms, and l represents an integer of 1 to 3,
• and wherein the light-resistant ultraviolet absorber exhibits a difference in transmittance (ΔTuv) of not larger than 2.0% at at least one of wavelengths of 380, 390 and 400 nm when measured under the following condition:
• <Condition for measuring difference in transmittance>
• a sample prepared by applying to a soda glass an acrylic resin and the ultraviolet absorber at a mass ratio of 0.6 to 3.4:0.1 and at a film thickness of 2 to 50 μm is irradiated with an ultraviolet for 70 hours under a condition(s) of wavelength 300 to 400 nm, irradiance 42 W/m2, black panel temperature 63° C.;
• based on a transmittance by UV-Vis transmission spectrum before irradiation (T1uv) and a transmittance by UV-Vis transmission spectrum after irradiation (T2uv), calculation is performed using the following formula:
• Difference
• ⁢
• in
• ⁢
• transmittance
• ⁢
• (
• Δ
• ⁢
• T
• ⁢
• u
• ⁢
• v
• )
• =
• T
• 1
• ⁢
• uv
• -
• T
• 2
• ⁢
• uv
• ⁢
• (
• %
• )
• ,
• or
• wherein each of PhBzT1c and PhBzT2c independently represents a substituted or unsubstituted 2-phenylbenzotriazole skeleton bonded to a thioaryl ring group represented by —S-A1c-S— in formula (3), wherein A1c represents a phenyl or naphthyl ring residue or is a group expressed by the following formula,
• wherein each of X1c and X2c independently represents a residue of a phenyl or naphthyl ring, each of n R1cs and p R2cs independently represents a hydrocarbon group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms or a hydroxy group, each of n and p represents an integer of 0 to 4, A2c represents a divalent hydrocarbon group that has 1 to 20 carbon atoms and may have hydrogen atoms therein substituted by, at least one of two ends thereof interrupted by, or carbon-carbon bonds therein interrupted by a monovalent or divalent group(s) selected from an aromatic group, an unsaturated group, a nitrogen-containing group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom, a divalent aromatic group or a sulfide group-S—, q represents an integer of 0 or 1;
• wherein each of —X1d—S-PhBzT1d- and -PhBzT2d-S—X2d— moiety in formula (4) independently represents a substituted or unsubstituted 2-phenylbenzotriazole skeleton that has a thioaryl ring group represented by —X1d—S— or —S—X2d— in formula (4) bonded to a phenyl moiety of a benzotriazole skeleton and A1d bonded to a position-2 phenyl skeleton Ph, each of X1d and X2d independently represents a residue of a phenyl or naphthyl ring, each of r R1ds and s R2ds independently represents a hydrocarbon group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms or a hydroxy group, each of r and s represents an integer of 0 to 5, A1d represents a divalent hydrocarbon group that has 1 to 20 carbon atoms and may have hydrogen atoms therein substituted by, at least one of two ends thereof interrupted by, or carbon-carbon bonds therein interrupted by a monovalent or divalent group(s) selected from an aromatic group, an unsaturated group, a nitrogen-containing group, a sulfur-containing group, an oxygen-containing group, a phosphorus-containing group, an alicyclic group and a halogen atom.