Benzotriazole UV absorbers having enhanced durability

A coating composition, stabilized with a benzotriazole, which benzotriazole exhibits enhanced durability and a low loss rate when incorporated in said coating, which composition comprises

• (a) a resin selected from the group consisting of a thermoset acrylic melamine resin, an acrylic urethane resin, an epoxy carboxy resin, a silane modified acrylic melamine, an acrylic resin with carbamate pendant groups crosslinked with melamine or an acrylic polyol resin crosslinked with melamine containing carbamate groups, and
• (b) 0.01 to 5% by weight, based on resin solids, of a benzotriazole of formula A, B, C or D ##STR13## wherein G.sub.1, G.sub.2 or T is an electron withdrawing radical,
• G.sub.1 is hydrogen or halogen,
• G.sub.2 is halogen, nitro, cyano, R.sub.3 SO--, R.sub.3 SO.sub.2 --, --COOG.sub.3, CF.sub.3 --, --P(O)(C.sub.6 H.sub.5).sub.2, --CO--G.sub.3, --CO--NH--G.sub.3, --CO--N(G.sub.3).sub.2, --N(G.sub.3)--CO--G.sub.3, ##STR14## G.sub.3 is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight of branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by 1 to 4 alkyl of 1 to 4 carbon atoms,
• R.sub.1 is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight of branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by 1 to 4 alkyl of 1 to 4 carbon atoms,
• R.sub.2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by 1 to 3 alkyl of 1 to 4 carbon atoms;
• or R.sub.2 is hydroxyl or --OR.sub.4 where R.sub.4 is straight or branched chain alkyl of 1 to 24 carbon atoms;
• or said alkyl substituted by one or more --OH, --OCO--R.sub.11, --OR.sub.4, --NCO or --NH.sub.2 groups or mixtures thereof;
• or said alkyl or said alkenyl interrupted by one or more --O--, --NH-- or --NR.sub.4 -- groups or mixtures thereof and which can be unsubstituted or substituted by one or more --OH, --OR.sub.4 or --NH.sub.2 groups or mixtures thereof;
• or R.sub.2 is --SR.sub.3, --NHR.sub.3 or --N(R.sub.3).sub.2 ;
• or R.sub.2 is
• --(CH.sub.2).sub.m --CO--X--(Z).sub.p --Y--R.sub.15
• wherein
• X is --O-- or --N(R.sub.16)--,
• Y is --O-- or --N(R.sub.17)--,
• Z is C.sub.2 -C.sub.12 -alkylene, C.sub.4 -C.sub.12 -alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C.sub.3 -C.sub.12 -alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
• m is zero, 1 or 2,
• p is 1, or p is also zero when X and Y are --N(R.sub.16)-- and --N(R.sub.17)--, respectively,
• R.sub.15 is a group --CO--C(R.sub.18).dbd.C(H)R.sub.19 or, when Y is --N(R.sub.17)--, forms together with R.sub.17 a group --CO--CH.dbd.CH--CO--, wherein R.sub.18 is hydrogen or methyl, and R.sub.19 is hydrogen, methyl or --CO--X--R.sub.20, wherein R.sub.20 is hydrogen, C.sub.1 -C.sub.12 -alkyl or a group of the formula ##STR15## wherein the symbols R.sub.1, R.sub.3, X, Z, m and p have the meanings defined above, and R.sub.16 and R.sub.17 independently of one another are hydrogen, C.sub.1 -C.sub.12 -alkyl, C.sub.3 -C.sub.12 -alkyl interrupted by 1 to 3 oxygen atoms, or is cyclohexyl or C.sub.7 -C.sub.15 aralkyl, and R.sub.16 together with R.sub.17 in the case where Z is ethylene, also forms ethylene,
• n is 1 or 2,
• when n is 1, R.sub.5 is Cl, OR.sub.6 or NR.sub.7 R.sub.8, or
• R.sub.5 is --PO(OR.sub.12).sub.2, --OSi(R.sub.11).sub.3 or --OCO--R.sub.11, or straight or branched chain C.sub.1 -C.sub.24 alkyl which is interrupted by --O--, --S-- or --NR.sub.11 and which can be unsubstituted or substituted by --OH or --OCO--R.sub.11, C.sub.5 -C.sub.12 cycloalkyl which is unsubstituted or substituted by --OH, straight chain or branched C.sub.2 -C.sub.18 alkenyl which is unsubstituted or substituted by --OH, C.sub.7 -C.sub.15 aralkyl, --CH.sub.2 --CHOH--R.sub.13 or glycidyl,
• R.sub.6 is hydrogen, straight or branched chain C.sub.1 -C.sub.24 alkyl which is unsubstituted or substituted by one or more OH, OR.sub.4 or NH.sub.2 groups, or --OR.sub.6 is --(OCH.sub.2 CH.sub.2).sub.w OH or --(OCH.sub.2 CH.sub.2).sub.w OR.sub.21 where w is 1 to 12 and R.sub.21 is alkyl of 1 to 12 carbon atoms,
• R.sub.7 and R.sub.8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain C.sub.3 -C.sub.18 alkyl which is interrupted by --O--, --S-- or --NR.sub.11 --, C.sub.5 -C.sub.12 cycloalkyl, C.sub.6 -C.sub.14 aryl or C.sub.1 -C.sub.3 hydroxylalkyl, or R.sub.7 and R.sub.8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring,
• when n is 2, R.sub.5 is one of divalent radicals --O--R.sub.9 --O-- or --N(R.sub.11)--R.sub.10 --N(R.sub.11)--,
• R.sub.9 is C.sub.2 -C.sub.8 alkylene, C.sub.4 -C.sub.8 alkenylene, C.sub.4 alkynylene, cyclohexylene, straight or branched chain C.sub.4 -C.sub.10 alkylene which is interrupted by --O-- or by --CH.sub.2 --CHOH--CH.sub.2 --O--R.sub.14 --O--CH.sub.2 --CHOH--CH.sub.2 --,
• R.sub.10 being straight or branched chain C.sub.2 -C.sub.12 alkylene which may be interrupted by --O--, cyclohexylene, or ##STR16## or R.sub.10 and R.sub.11 with the two nitrogen atoms form a piperazine ring,
• R.sub.14 is straight or branched chain C.sub.2 -C.sub.8 alkylene, straight or branched chain C.sub.4 -C.sub.10 alkylene which is interrupted by --O--, cycloalkylene, arylene or ##STR17## where R.sub.7 and R.sub.8 are independently hydrogen, alkyl of 1 to 18 carbon atoms or R.sub.7 and R.sub.8 together are alkylene of 4 to 6 carbon atoms, 3-oxapentamethylene, 3-iminopentamethylene or 3-methyliminopentamethylene,
• R.sub.11 is hydrogen, straight or branched chain C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.12 cycloalkyl, straight or branched chain C.sub.3 -C.sub.8 alkenyl, C.sub.6 -C.sub.14 aryl or C.sub.7 -C.sub.15 aralkyl,
• R.sub.12 is straight or branched chain C.sub.1 -C.sub.18 alkyl, straight or branched chain C.sub.3 -C.sub.18 alkenyl, C.sub.5 -C.sub.10 cycloalkyl, C.sub.6 -C.sub.16 aryl or C.sub.7 -C.sub.15 aralkyl,
• R.sub.13 is H, straight chain or branched C.sub.1 -C.sub.18 alkyl which is substituted by --PO(OR.sub.12).sub.2, phenyl which is unsubstituted or substituted by OH, C.sub.7 -C.sub.15 aralkyl or --CH.sub.2 OR.sub.12,
• R.sub.3 is alkyl of 1 to 20 carbon atoms, hydroxyalkyl of 2 to 20 carbon atoms, alkenyl of 3 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, aryl of 6 to 10 carbon atoms or said aryl substituted by one or two alkyl of 1 to 4 carbon atoms or 1,1,2,2-tetrahydroperfluoroalkyl where the perfluoroalkyl moiety is of 6 to 16 carbon atoms,
• L is alkylene of 1 to 12 carbon atoms, alkylidene of 2 to 12 carbon atoms, benzylidene, p-xylylene or cycloalkylidene, and
• T is --SO--, --SO.sub.2 --, --SO--E--SO--, --SO.sub.2 --E--SO.sub.2 --, --CO--, --CO--E--CO--, --COO--E--OCO--, --CO--NG.sub.3 --E--NG.sub.3 --CO-- or --NG.sub.3 --CO--E--CO--NG.sub.3 --,
• where E is alkylene of 2 to 12 carbon atoms, cycloalkylene of 5 to 12 carbon atoms, or alkylene interrupted or terminated by cyclohexylene of 8 to 12 carbon atoms,
• which benzotriazole exhibits enhanced durability and low loss rate values when the coating is exposed to actinic radiation as witnessed by a loss of less than 0.22 absorbance units after exposure for 1200 hours, or less than 0.27 absorbance units after 1500 hours exposure, or less than 0.40 absorbance units after 2500 hours exposure in a Xenon-Arc Weather-Ometer, and
• with the proviso that the benzotriazole is not
• (a) 5-n-dodecylsulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole
• (b) 5-benzenesulfinyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
• (c) 5-benzenesulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
• (d) 5,5'-sulfonylbis[2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole];
• (e) 5-benzenesulfonyl-2-[2-hydroxy-3-tert-butyl-5-(2-octyloxycarbonylethyl)-ph enyl]-2H-benzotriazole;
• (f) 5-benzenesulfonyl-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H- benzotriazole;
• (g) 3-(5-benzenesulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinn amic acid;
• (h) 3-(5-benzenesulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinn amamide;
• (i) an isomeric mixture of 3-[3-(5-benzenesulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydroc innamoyloxy]-2-hydroxypropyl methacrylate and 2-[3-(5-benzenesulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydroc innamoyloxy]-3-hydroxypropyl methacrylate;
• or
• (j) 5-benzenesulfonyl-2-{2-hydroxy-3-tert-butyl-5-[2-(.omega.-hydroxy-octa(eth yleneoxy)-carbonylethyl]phenyl}-2H-benzotriazole.