CS227004B2 - Method of stabillizing one-or two-layered baking varnish - Google Patents

Description

binder 0.01 to 5% by weight of a compound containing a group of formula (I)

BACKGROUND OF THE INVENTION The present invention relates to a method for stabilizing hot-crosslinking alkyd and acrylic resist baking varnishes against light and moisture by the addition of polyalkylpiperidine derivatives as well as stabilized effect varnishes for metals.

It has been found that the ever-existing problems of metallic effect lacquers, and in particular the appearance of cracks and gloss loss, by using hot-crosslinkable alkyd or acrylic resin baking varnishes can be satisfactorily solved by adding light-protective agents based on polyalkylpiperidine derivatives. optionally using additional stabilizers.

The invention therefore relates to the stabilization and single- or double-layer to evaporate ^with for consent paint containing as a binder a hot crosslinkable alkyd or acrylic resin pigmented metallic pigment, light stabilizer is especially effective coatings with metal-based hot-crosslinkable polyacrylate resins containing copolymerized styrene and, in particular, automotive coatings, characterized in that an amount of ₃ cm _3, or an acid addition salt or a metal complex of such a compound or, optionally, an additional light-protective agent of a quantity selected is added to the lacquer as a stabilizer. such that the sum of all light-protective agents is 0.02 to 5% by weight, based on solvent-free binder, and optionally other additives such as antioxidants, plasticizers, leveling agents, curing accelerators, thickeners, dispersants or adhesion promoters.

Compounds containing a group of the general formula used according to the invention

They are well known in the art and have already been used to protect against light degradation, cf. However, they have never been used to stabilize effect-like lacquers with a metallic appearance, especially in connection with the typical problem of cracking and gloss loss.

In particular, the light-protective agents used in the process of the invention belong to the following classes of compounds:

aj Light-protecting agents of formula II

wherein n is 1 to 4, preferably 1 or 2,

R 1 is hydrogen, oxy, C 1 -C 18 alkyl, C 3 -C 8 alkenyl, C 3 -C 8 alkynyl, C 7 -C 12 aralkyl, C 1 -C 8 alkanoyl C 3 -C 5 alkenoyl; glycidyl;

-CH 2 CH-Z

........... and ....... ....... .

OH where is

Z is hydrogen, methyl or phenyl, wherein R 1 is preferably hydrogen, alkyl of 1 to 12 carbon atoms, allyl, benzyl, acetyl, acrylic and

R2 when n is 1 is hydrogen, C1-C18alkyl optionally interrupted by one or more oxygen atoms, cyanethyl, benzyl or glycidyl, a monovalent aliphatic, cycloaliphatic, arallphatic or aromatic moiety carboxylic acids, carbamic acids or phosphorus-containing acids or a monovalent silyl radical, preferably a C 2 -C 18 aliphatic carboxylic acid radical, C 5 -C 12 cycloaliphatic carboxylic acids or C 7 -C 15 aromatic carboxylic acids, if n represents 2, denotes an alkylene group having 2 to 12 carbon atoms, an alkenylene group having 4 to 12 carbon atoms, a xylylene group, a divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, dicarbamic acid or phosphorus-containing acid, or a divalent silyl C 2 -C 36 aliphatic dicarboxylic acid, preferably C 8 -C 24 cycloaliphatic or aromatic dicarboxylic acid, preferably C 8 -C 14 aliphatic, cycloaliphatic or aromatic dicarbamic acid, if n is 3, a trivalent aliphatic, cycloaliphatic or aromatic tricarboxylic acid, an aromatic tricarbamic acid or a phosphorus-containing acid, or a trivalent silyl radical when n is 4 is a tetravalent aliphatic, cycloaliphatic or aromatic tetracarboxylic acid.

When some substituents are C 1 -C 12 alkyl, this may be, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-bexyl, n-octyl , 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl.

As C 1 -C 18 alkyl, R 1 or R 2 may, for example, be as defined above, and moreover, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When R 1 is a C 3 -C 8 alkenyl group, it may be, for example, 1-propenyl, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl, 4-tert-butyl-2- butenyl group.

R1 in the meaning of an alkynyl group having from 3 to 8 carbon atoms is preferably a propargyl group.

In the meaning of an ar (C7 -C12) alkyl group, R @ 1 is in particular a phenethyl group or, preferably, a benzyl group.

For the C význam-C alk alkanoyl group, R znamená is, for example, a formyl, piperionyl, butyryl, octanoyl or preferably acetyl group and, in the C význam-C alk alk alkenoyl group, in particular an acryloyl group.

R2 as a monovalent carboxylic acid residue means, for example, acetic, stearic, salicylic, methacrylic, maleic, benzoic or (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid) radical.

R2 in the meaning of a divalent dicarboxylic acid residue means, for example, adipic acid, suberinic acid, sebacic acid, violet, dibutylmalonic acid, dibenzylmalonic acid, butyl- (3,5-di-tert-butyl-4-hydroxybenzyljmalonic acid) or a bicycloheptenedicarboxylic acid residue.

R2 in the meaning of the trivalent radical tri227004 of a carboxylic acid means, for example, a trlmellitic acid residue or a nitrilotriacetic acid residue.

R2 in the meaning of a tetravalent tetracarboxylic acid residue means, for example, a pyromellitic acid residue.

Ra in the meaning of a divalent dicarbamic acid residue means, for example, a hexamethylenedicarbamic acid or 2,4-toluylenedicarbamic acid residue.

Examples of light-protecting polyalkylpiperidine compositions of this class are:

1. 4-hydroxy-2,2,6,6-tetramethylpiperidine;

2. 1-Allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine;

3. 1-benzyl-4-hydroxy-2,2,6,6-tetramethylpiperidine;

4. 1- (4-tert-butyl-2-butenyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine;

5. 4-stearoyloxy-2,2,6,6-tetramethylpiperidine;

6. 1-ethyl-4-sulfonyloyloxy-2,2,6,6-tetramethylpiperidine;

7. 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine,

8. 1,2,2,6,6-Pentamethylpiperidin-4-yl- N- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

9. 1-benzyl-2,2,6,6-tetramethyl-4-piperidinyl maleate,

10. (di-2,2,6,6-tetramethylpiperidin-4-yl) adipate;

11. (di-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,

12. (di-1,2,3,6-tetramethyl-2,6-diethylpiperidin-4-yl) sebacate,

13. (di-1-allyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate,

14. 1-Propargyl-4- (J-cyanoethyloxy-2,2,6,6-tetramethylpiperidine)

15. 1-acetyl-2,2,6,6-tetramethylpiperidin-4-yl acetate;

16. trimellitic acid tri- (2,2,6,6-tetramethylpiperidin-4-yl) ester,

17. 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine;

18. Dibutylmalonic acid di- (1,2,2,6,6-pentamethylpiperidin-4-yl) ester

19. Butyl- (3,5-di-tert-butyl-4-hydroxybenzyl) malonic acid di- (1,2,2,6,6-pentamethylpiperidin-4-yl) ester;

20. Dibenzylmalonic acid di- (1,2,2,6,6-pentamethylpiperidin-4-yl) ester

21. Dibenzylmalonic acid di- (1,2,3,6-tetramethyl-2,6-diethylpiperidin-4-yl) ester

22. hexane-1 ', 6'-bis- (4-carbamoyloxy-1-n-butyl-2,2,6,6-tetramethylpiperidine),

23. toluene-2 ‘, 4‘-bis- (4-carbamoyloxy-1-n-propyl-2,2,6,6-tetramethylpiperidine),

24. dimethyl-bis- (2,2,6,6-tetramethylpiperidine-4-oxysilane),

25. phenyl-tris- (2,2,6,6-tetramethylpiperidin-4-oxy) silane;

26. tris- (1-propyl-2,2,6,6-tetramethylpiperidin-4-yl) phosphite;

27. tris- (1-propyl-2,2,6,6-tetramethylpiperidin-4-yl) phosphate,

28. phenyl [bis- (1,2,2,6,6-pentamethylpiperidin-4-yl)] phosphonate.

(b) Light-protecting agents of the general formula (III)

(III) where n is 1 or 2,

R1 has the meaning given in paragraph a),

R 5 is hydrogen, C 1 -C 12 alkyl, C 5 -C 7 cycloalkyl, C 7 -C 8 aralkyl, C 2 -C 18 alkanoyl, C 3 -C 5 alkenoyl, benzoyl ,

R 4 when n is 1 is hydrogen, C 1 -C 18 alkyl, C 5 -C 7 cycloalkyl, C 2 -C 8 alkenyl optionally substituted with cyano, carbonyl or carbamide , a glycidyl group, a group of formula —CH2 —CH (OH) —Z, or —CONH — Z wherein Z is hydrogen, methyl or phenyl, when n is 2, is an alkylene group having 2 to 12 carbon atoms, arylene group having 6 to 12 carbon atoms, a xylilene group, a group of the formula —CH2 —CH (OH) —CH2 — or a group of the formula —CH2 —CH (OH - CH2 —O — X— —O — CH2-CH ( OH) —CH2 - wherein X represents a C2-C10 alkylene group, a C6-C15 arylene group, a C6-C12 cycloalkylene group, or provided that R3 is not an alkanoyl, alkenoyl or benzo group R4 also denotes a bivalent radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic or dicarbamic acid or also a group -CO- or R5 and R4 together represent in the case where n is the number 1 a cyclic radical of an aliphatic polyaromatic 1,2-dicarboxylic acid or 1 3-dicarboxylic acids.

Where the substituents are C 1 -C 18 alkyl, the substituents in (a) are as previously defined,

When the substituents are C 5 -C 7 cycloalkyl, they are in particular cyclohexane.

R3 in the meaning of a (C až-C ar ar) aralkyl group is especially a phenethyl or especially benzyl group.

R3 for C 2 -C 18 alkanoyl is, for example, propionyl, butyryl, octanoyl, dodecanoyl, hexadecanoyl, octadecanoyl, but preferably acetyl, and especially C 3 -C 5 alkenoyl is acrylicyl.

R 4 as C 2 -C 8 alkenyl optionally substituted by cyano, carbonyl or carbamide means, for example, 1-propenyl, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl, 2-dicyanvinyl, 1-methyl-2-cyano-2-methoxycarbonylvinyl, 2,2-diacetylaminovinyl.

When some substituents are C 2 -C 12 alkylene, they are, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.

When some substituents are an arylene group having 6 to 15 carbon atoms, they are, for example, o-phenylene, m-phenylene, p-phenylene, 1,4-naphthylene or 4,4 dif-diphenylene.

C 6 -C 12 -cycloalkylene is in particular cyclohexylene.

Examples of polyalkylpiperidine light-retardants of this class are:

29. N, N‘-bis- (2,2,6,6-tetramethylpiperidin-4-yl) hexamethylene-1,6-diamine;

30. N, N‘-bis- (2,2,6,6-tetramethylpiperidin-4-yl) hexamethylene-1,6-diacetamide;

31. 1-acetyl-4- (N-cyclohexylacetamido) -2,2,6,6-tetramethylpiperidine;

32. 4-Benzylamino-2,2,6,6-tetramethylpiperidine

33. N, N‘-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -N, N‘-dibutyl adipamide,

34. N, N‘-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -N-N‘-dicyclohexyl- (2-hydroxypropylene);

35. N, N‘-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -p-xylylenediamine,

36. a compound of the formula

37. 4- [bis-2-hydroxyethyl) amino-1,2,2,6,6-pentamethylpiperidine;

38. 4- (3-methyl-4-hydroxy-5-tert-butyl-benzoic acid-amido] -2,2,6,6-tetramethylpiperidine,

39. 4-Methacrylamido-1,2,2,6,6-pentamethylpiperidine

40. N-methyl- [3- (N- (2,2,6,6-tetramethylpiperidin-4-yl)] -aminoacrylic acid methyl ester).

c) Light-protecting agents of the general formula IV

where n is 1 or 2, R 1 is as defined in a), and R 5 when n is 1 is C 2 -C 8 alkylene or hydroxyalkylene, C 4 -C 22 acyloxyalkylene and if n is 2, is a group of formula (--CH 2) 2 C (CH 2 =) 2.

R 5 as C 2 -C 8 alkylene or hydroxyalkylene means, for example, ethylene, 1-methylethylene, propylene, 2-ethylpropylene, 2-ethyl-2-hydroxymethylpropylene.

R 5 as acyloxyalkylene having 4 to 22 carbon atoms means, for example, 2-ethyl-2-acetyloxymethylpropylene.

Examples of light-protecting polyalkylpiperidine compositions of this class are:

41. 9-aza-8,8,10,10-tetramethyl-1,5-dioxaspiro [5.5] undecane;

42. 9-aza-8,8,10,10-tetrainethyl-3-ethyl-1,5-dioxaspiro [5,5] dean;

43. 8-aza-2,7,7,8,9,9-hexamethyl-1,4-dioxyspiro [4,5] dean;

44. 9-aza-3-hydroxymethyl-3-ethyl-8,8,9,10,10-pentamethyl-1,5-dioxaspiro [5,5] undecane;

45. 9-aza-3-ethyl-3-acetoxymethyl-9-acetyl-8,8,10,10-tetramethyl-1,5-dioxaspiro [5.5] undecane;

AT

46. 2,2,6,6-tetramethylplperidine-4-spiro-2'- (1,3'-dioxane) -5'-spiro-5 '- (1', 3'-dioxane) -2 '-spiro -4 "'- (2"' ₎ 2 "^< , 6"', 6 "' - tetramethylpiperidine.

(d) Light retardants of the general formula (V)

where n is 1 or 2,

Ri is as defined in paragraph a),

Re represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an allyl group, a benzyl group, a glycidyl group, an alkoxyalkyl group having 2 to 6 carbon atoms,

R7 when n = 1 is hydrogen, alkyl of 1 to 12 carbon atoms, alkenyl of 3 to 5 carbon atoms, aralkyl of 7 to 9 carbon atoms, cycloalkyl of 5 to 7 carbon atoms, hydroxyalkyl (C 2 -C 4) group, (C 2 -C 6) alkoxyalkyl, (C 6 -C 10) aryl group, glycidyl group, general formula

- (CH 2) _m -COO-Q or of the general formula - (CH ₂ ) _m —Cb —CO · —Q wherein m is 1 or 2 and

C 1 -C 4 alkyl or phthyl when n = 2, R 7 is C 2 -C 12 alkylene, C 6 -C 12 aryl group, or -CH 2 -CH (OH) - GH 2 - O - X - O - CH 2 - CH [OH) - CH 2 - where is

X is C 2 -C 10 alkylene, C 6 -C 15 arylene, C 6 -C 12 cycloalkylene, or -CH 2 CH (O 2) CH 2 - (OCH 2 -CH) O 2 - (CH 2) 2 where

Z * is hydrogen, alkyl of 1 to 18 carbon atoms, allyl, benzyl, alkanoyl of 2 to 12 carbon atoms or benzoyl.

When the substituents are an alkyl group having 1 to 12 carbon atoms, it is, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n a n-butyl, n-decyl, n-undecyl or n-dodecyl group.

Z‘ in the meaning of an alkyl group having 1 to 18 carbon atoms means, for example, one of the abovementioned alkyl groups and, in addition, for example an n-tridecyl, n-tetradecyl, n-hexadeeyl or n-octadecyl group.

When the substituents are C 2 -C 6 alkoxyalkyl, it is, for example, methoxymethyl, ethoxymethyl, propoxymethyl, tert-butoxymethyl, ethoxyethyl, ethioxypropyl, n-butoxyethyl, tert-butoxyethyl, isopropoxyethyl or propoxy.

R 7 in the meaning of a C 3 -C 5 alkenyl group means, for example, 1-propenyl, allyl, methallyl, 2-butenyl or 2-pentenyl.

R7 for C7 -C9 -alkyl is preferably phenethyl or especially benzyl, and for C5-C7-cycloalkyl is primarily cyclohexyl.

R7 in the meaning of a C2 -C4 hydroxyalkyl group is, for example, a 2-hydroxyethyl, 2-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl group.

R7 in the meaning of a (C6 -C10) aryl group is, for example, in particular phenyl, .alpha.-naphthyl or .beta.-naphthyl optionally substituted with halogen or C1 -C4 alkyl.

R7 in the meaning of a C2 -C12 alkylene group means, for example, an ethylene, propylene, 2,2-dimethylpropylene, tetramethylene hexamethylene, octamethylene, decamethylene or dodecamethylene group.

R7 in the sense of an arylene group having 6 to 12 carbon atoms means, for example, o-phenylene, m-phenylene or p-phenylene, 1,4-naphthylene or 4,4‘-diphenylene.

Z‘ in the meaning of C 2 -C 12 alkanoyl is, for example, propionyl, butyryl, octanoyl, dodecanoyl, but preferably acetyl.

X is C2 -C6 alkylene, C6 -C6 arylene or C6 -C12 cycloalkylene is as defined in b).

Examples of light-protecting polyalkylpiperidine compositions of this class are:

47. 3-benzyl-1,3,8-triaza-7,7,9,9-tetramethylspiro 4,5] decane-2,4-dione;

227001

48. 3-n-octyl-1,3,8-triaza-7,7,9,9-tetramethylspiro [4,5] decane-2,4-dione;

49. 3-allyl-1,3,8-triaza-1,7,7,9,9-pentamethylspiro [4,5] decane-2,4-dione;

50. 3-glycidyl-1,3,8-triaza-7,7,8,9,9-penta methylspiro [4,5] decane-2,4-dione or compounds of the following formulas:

ch ₃ CH. AND , NH ~ O0 in CH ₃ CH ₃ J < 1 O = C-NH 3 / V 1 X H ~ CH. X 'C ~ N ~ CH ₂ CH (OHJCH 2 -) OCH 2 CH (OH) ch ₂ cwf ch ₃ b 1/0 CH ₃ ^x CH ₃

e) Light-protecting agents of the general formula VI

(VI) wherein n is 1 or 2 and R e is a group of formula

wherein R 1 is as defined in (a), Y represents an oxygen atom or a group of the formula -NR 11.

A is an alkylene group having 2 to 6 carbon atoms and m is 0 or 1,

R9 is Re, NR11R12, -OR13, —NHCH2OR13, or —N (CH2OR13) 2,

R 10 when n is 1, R e and R 9, and when n is 2, a group of the formula

-Y-Q-Y, where

Q represents a C 2 -C 6 alkylene group or an optionally interrupted group of the formula

N— (RiáJ—,

C 1 -C 12 alkyl, C 1 -C 4 cyclohexyl, benzyl or hydroxyalkyl or ^{R 1} CH ₃ CH ₃

R 12 is C 1 -C 12 alkyl, cyclohexyl, benzyl, C 1 -C 4 hydroxyalkyl,

R (13) is hydrogen, alkyl of 1 to 12 carbon atoms or phenyl,

R @ 11 is hydrogen or --CH2 OR @ 13 or

R11 and R12 together represent an alkylene group having 4 to 5 carbon atoms or an oxoalkylene group or the like

R 11 and R 12 are each a group of formula

When certain symbols are C 1 -C 12 alkyl, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl , n-nonyl, n-decyl, n-undecyl or n-dodecyl.

When certain symbols are C 1 -C 4 hydroxyalkyl, it is, for example, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.

And, for the C 2 -C 6 alkylene group, for example, is an ethylene, propylene, 2,2-dimethypropylene, tetramethylene or hexamethylene group.

When Ru and R12 together represent an alkylene group having 4 to 5 carbon atoms or an oxaalkylene group, it is, for example, tetramethylene, pentamethylene or 3-oxapeintamethylene.

Examples of light-protecting polyalkylpiperidine compositions of this class are compounds of these formulas.

Cs CH ₃

551

C / A.CH ₃

CH 2 CH 2 NH ς

In CH 2 CH 3 ^CH 3 NH 3 CH 2 CH 3 NH-CH 2 NH-CH 2 CH 3 -

59)

O «ο ιη

(f) Light-retardant of general formula (VII)

where n is 1 or 2,

R 14 when n is 1 is C 4 -C 18 alkyl, C 7 -C 12 aralkyl, -C 0 -C 8 alkyl, cyano C 1 -C 4 alkyl, —COORie, —OCOR17 or

-CH2CH (OH)

or a hydroxyl group, wherein

R15 is C1 -C12 alkyl, C2 -C4 alkenyl or phenyl;

R 1 represents an alkyl group having 1 to 18 carbon atoms,

R 17 is C 1 -C 18 alkyl, C 2 -C 10 alkenyl, cyclohexyl, benzyl or C 6 -C 10 aryl or, if n is 2, R 14 is C 4 -C 12 alkylene; a butylene-1,4-group, a xylylene group, a group of the general formula ¹ - (CH 2 J 2 -OOC-R 11 -COO- (CH 2) 2 - or a group of the formula-1CH 2 -OOC-R 9 -COO-CH 2 -,

R 1 represents an alkylene group, a phenylene group or a cyclohexylene group and

R19 is C2 -C10 alkylene, xylylene or cyclohexyl.

When some substituents are C 1 -C 12 alkyl, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl , n-nonyl, n-decyl, n-undecyl or n-dodecyl.

When some substituents are C 1 -C 18 alkyl, they are, for example, the groups mentioned above and moreover, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When some groups are C 2 -C 10 alkylene, it is, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene or decamethylene.

R14 as C 4 -C 18 alkyl means, for example, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, 1,1-dimethyl-2-tert. n -butyl ethyl, n-nonyl, n-decyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

R14 as C1 -C4 alkyl substituted with cyano is, for example, cyanomethyl, cyanethyl, 3-cyano-n-propyl, 4-cyano-n-butyl.

R14 as C 4 -C 12 alkylene is, for example, 2,2-dimethylpropyleine, tetramethylmethyl, hexamethylene, octamethylem, decamethylene or dodecamethylene.

R14 as C7 -C12 aralkyl is especially phenethyl, p-methylbenzyl or especially ¹ benzyl.

R15 as C2 -C4 alkenyl means, for example, vinyl, 1-propenyl, allyl, methallyl, 2-butenyl.

R17 for C 2 -C 10 alkenyl means, for example, the groups exemplified as R 15 for alkenyl and in addition ¹ is for example a crotyl, 2-hexanyl, 2-octenyl or 2-decenyl group.

R17 in the meaning of a (C6 -C10) aryl group means, for example, a phenyl group optionally substituted in the ortho or meta position by a methyl, ethyl, isopropyl, n-butyl or tert-butyl group.

Examples of light-protecting polyalkylpiperidine compositions of this class are:

60. bis - [, N- (2,2,6,6-tetraimethylpiperidinoyl-ethyl) sebacate,

61. N- (2,2,8,6-tetramethylpiperidine) acetic acid in the form of n-octyl ester,

62. 1,4-bis- (6,6-2.2 _t tetrainethylpiper: i'dinoJ -2-n-butenyl.

-GNE-CO -NH-CH _Z OR _Z

g) Light-protecting agents of the general formula VIII

q-E-CO-NH-CH 2 OR 4 (VIII) wherein G is C 2 -C 6 alkylene or C 6 -C 12 arylene, or

R3 is --E - CO - NH - CH2 - OR2.

where

Q is --N (R 3) - or - O,

E represents a C 1 -C 3 alkylene group, a group of the formula -CH 2 -CH (R 4j-O), wherein R 4 is a hydrogen atom, a methyl or phenyl group, a group of the formula - (CH 2) 3 -NH, or a single bond,

R 1 -hydrogen, C 1 -C 8 alkyl, C 3 -C 8 alkenyl, C 3 -C 8 alkynyl, C 7 -C 12 aralkyl, C 1 -C 8 alkanoyl , (C 3 -C 5) alkanoyl, glycidyl,

R @ 2 is hydrogen or C1 -C18 alkyl,

R3 is hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 7 carbon atoms, aralkyl of 7 to 12 carbon atoms, cyanethyl group, aryl of 6 to 10 carbon atoms carbon atoms, a group of the formula -CH2-CH (R4j-OH, wherein R4 is as defined above), a group of the formula

C

When some substituents are alkyl of 1 to 18 carbon atoms, it is, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, methyl, ethyl, n-propyl, n-butyl. -ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, or n-octadecyl.

When some substituents are C7 -C12 aralkyl, it is, for example, phenethyl or especially benzyl.

R 1 as C 3 -C 8 alkenyl means, for example, 1-propenyl, allyl, methallyl, 3-butenyl, 2-pentanyl, 2-hexenyl, 2-octenyl or 4-tert-butyl-2-butenylo - your group.

R1 in the meaning of C3 -C8 alkynyl is preferably propargyl. For the C 1 -C 8 alkanoyl group, R 1 is, for example, a formyl, propionyl, butyryl, octanoyl group, but preferably an acetyl group, and in the C 3 -C 5 alkenoyl group, R 1 is especially an acryloyl group.

R 3 represents, in the meaning of a C 5 -C 7 cycloalkyl group, in particular a cyclohexyl group.

R3 in the sense of an aryl group having 6 to 10 carbon atoms is, in particular, phenyl, [alpha] -naphthyl and [beta] -naphthyl, these groups being optionally substituted by a halogen atom or a C1-C4 alkyl group. E for C 1 -C 3 alkylene is, for example, methylene, ethylene or propylene.

G for C 2 -C 2 alkylene is, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene or hexamethylene, and arylene or a group of the formula

6 to 12 carbon atoms means an o-phenylene, m-phenylene or p-phenylene, 1,4-naphthylene or 4,4‘-diphenylene group.

Examples of light-protecting polyalkylpiperidine compositions of this class are:

63. N-hydroxymethyl-N, Z-e-tetramethylpiperidin-4-yl-mono-amino,

64. N-methoxymethyl-N‘-2,2,6,6-tetramethylpiperidin-4-yl-urea,

65. N-methoxymethyl-N‘-n-dodecyl-N‘-2,2,6,6-tetramethylpiperidin-4-yl-urea;

66. O- (2,2,6,6-Tetramethylpiperidin-4-yl) -N-methoxymethylurethane.

F)

Polymeric compounds whose repeating structural unit contains a polyalkylpiperidime radical of the formula I, in particular polyesters, polyethers, polyamides, polyamines, polyurethanes, polyureas, polyaminotriazines, poly (meth) acrylates, poly (methacrylamides and copolymers thereof containing such radicals.

Examples of light-protecting polyalkylpiperidine compositions of this class are compounds of the following formulas, wherein m is from 2 to about 200.

67)

OO

II

-co fl o CH ₂ ) f C-O N- CH 2 CH 2 O-O-CH 2 -CCH,

CH,

m.

b - (CH ₂ ) ₃ -HH-Cch ₃ C ₂ H _{5 -}

O

II

C-

72)

CH-CH (OH) CH _Z CH ₃ CH ₃ in \ 3 - ^CH 2 ^{CH = CH-C Η} ζ \ ζ) ~ O _CH3 CH ₅ CH ₃ CH ₃

m

-ccc (CH _Z ) _&

O

II c ₂ h _s oc ₂ h _s

75)

It is also possible to use polyalkylpiperidine derivatives of classes a) to f) which form a chemical bond with the lacquer binder. This occurs when the polyalkylpiperidine derivative has a suitable reactive group, such as a glycidyl or methyl group, for such a reaction.

Examples of such compounds are class gj polyalkylpiperidine derivatives containing methyl or methylol ether groups.

If the polyalkylpiperidine compounds are basic compounds, they can form salts with acids. Possible inorganic acids or organic carboxylic acids, sulphonic acid, phosphonic acid or phosphinic acid, such as, for example, hydrochloric, b-ore, phosphoric, acetic, salicylic, toluenesulphonic acids or benzoic acid.

The polyalkyl piperidine compounds may form complexes with metal complexing compounds; such metal complexing compounds are, for example, zinc acetate, cobalt acetylacetonate, nickel acetylacetonate, aluminum acetylacetonate, nickel benzoate or aluminum benzoylacetonate.

Acrylic resin lacquers which can be stabilized against light, moisture and oxygen by the method according to the invention are conventional acrylic resin baking lacquers, as described, for example, in H. Kittels Lehrbuch der Lacke und Beschichtungen, Volume 1, Vol. 2, pp. 735 and 742 (Berlin, 1972) and optionally H. Wagner, HF Sarx, Lackkunstharze, pp. 229-235.

Of particular interest is the stabilization according to the invention of effect metallic lacquers based on polyacrylate resins containing hot-crosslinkable styrene polymers. With these resins, metal-like effect lacquers with excellent physical and chemical properties can be produced, unless the built-in styrene content results in cracks due to weathering. Surprisingly, however, the addition of the polyalkylpiperidine derivatives according to the invention, in particular in combination with the known light-protective agent of the ultraviolet ray absorber type, makes it possible to achieve excellent stabilization against said crack formation.

Also of particular importance is the stabilization according to the invention of the metallic alkyd-based effect lacquers. The stabilization of alkyd-based effect lacquers with light-protecting agents according to the prior art of the type of ultraviolet ray absorber is also problematic and does not constitute a satisfactory technical solution.

By adding the light-protective agents based on the polyalkylpiperidine derivatives according to the invention, optionally together with other stabilizers, it is now also possible to satisfactorily stabilize the alkyd resin-based effect lacquers against light and moisture, in particular to prevent cracks.

Alkyd resin based lacquers which can be stabilized by the method according to the invention against light and moisture are conventional stoving lacquers which are used, in particular, for the automotive coating (so-called automotive lacquers), for example alkyd-based lacquers. melamine resins and alkydacrylmelamine resins.

Also, effect-free lacquers based on oil-free polyesters can be successfully stabilized by the process according to the invention.

In order to achieve the metallic effect, conventional aluminum pigments are used in an amount of 1 to 10% by weight, based on the solvent-free binder (lacquer resin). Effective metallic-look lacquers stabilized by the process according to the invention are applied as usual in two ways by either single-layer or double-layer coating. In a two-layer coating, an aluminum pigment-containing layer is first applied and then a clear topcoat layer.

The polyalkylpiperidine derivative is added in an amount of 0.01 to 5% by weight, based on the solvent-free binder, preferably in an amount of 0.5 to 1% by weight.

The lacquers may contain solvents known per se, or they may be dissolved or dispersed in water or free of solvents.

In a two-layer coating, the polyalkylpiperidine derivative used for the stabilization according to the invention can be either only in the unpigmented topcoat or in both the unpigmented topcoat and the base pigment containing aluminum pigment. In the manufacture of acrylic resins or alkyd resins modified with acrylic compounds, polymerizable polyalkylpiperidine derivatives (e.g., compounds 7 and 39) can be polymerized into a resin.

However, incorporation into the lacquer binder is also possible by polycondensation in the manufacture or by firing of melamine, alkyd or polyester resins. Examples of condensable polyalkylpiperidine derivatives include compounds number 1, 26, 27 as well as 1-hydroxyethyl-4-hydroxy-2,2,6,6-tetramethylpiperidine. For example, incorporation of polyadditions is possible by reacting the free carboxylic acid groups in the acrylic resin with the glycidyl groups of the polyalkylpiperidine derivative. These carboxyl groups can be incorporated in the polymerization of acrylic acid or derivatives thereof.

In these cases, it is an additional advantage that the light protection agent is not removable by extraction or migration, so that it has a longer duration of action.

In order to achieve maximum light retention, it may be advantageous to use other known light protection agents, such as, for example, benzophenone, oxanilide, benztriazoles or acrylic acid derivatives, or metal-containing light protection agents such as organic nickel compounds.

In the case of such combinations, the total amount of all light retardants is 0.02 to 5% by weight, preferably 0.5 to 2% by weight, based on the varnish resin.

Other additives that the lacquer may contain are antioxidants such as sterically hindered phenol derivatives, organic phosphorus compounds such as phosphites, phosphonites or phosphines, plasticizers, flow control agents, curing accelerators such as organic salts of cobalt, manganese or the like. zirconium, thickeners, dispersants and adhesion promoters.

The following examples illustrate the use of the polyalkylpiperidine derivatives according to the invention in metallic paints based on alkyd resins which form the binder system. Parts and percentages are by weight.

Example 1

Light stabilization of a two-layer effect metal varnish (crack test) based on a binder system containing an alkyd resin.

Basic recipe of lacquer

and)

Primer with metallic look

Alphthalate VAN 21/1 (Hochst) 13.15 parts

CAB 381.01 / 18% in butyl acetate (Eastman Chemical Corp.J 55.00 part

Uresin B (Hochst J 2.50 part

Maprenal VMF 80/15 (Hochst) 3.45 part Alcoa 726 (Aluminum

Corp. ot America) 6.50 parts

15% BYK 300 solution (BYK Mallinckrodt) in butyl acetate / xylene system 2.00 parts xylene 6.00 parts butyl glycol 5.00 parts butyl acetate / xylene = 1/1 6.40 parts bj

Unpigmented topcoat

Alftalat AC 451 n (Hochst) 28.5 parts

Synthacryl SC 303 (Hochst) 30.7 parts

Maprenal VMF 80/15 (Hochst) 22.8 parts butyl glycol 4.3 parts butyl glycol acetate 1.7 parts

Solvesso 150 (Esso) 8.5 part

Solvesso 100 (Esso) 3.5 part

Individual business names have the following meaning:

Alftalat VAN 21/1, AC 451 n is a commercial alkyd resin;

CAB 381.01 is cellulose acetobutyrate;

Uresin B is a commercial resin based on carbamic acid;

Maprenal VMF 80/15, RT MF 590 and MF 650 is a commercial melamine-formaldehyde resin;

Alcoa 726 is a silver aluminum pigment;

BYK 300 is a silicone oil-based flow agent;

Synthacryl SG 303 and SC 300 is a commercial acrylic resin;

Solvesso · 150 and 100 is a mixture of aromatic solvents;

Polysolvan 0 is a technical butyl glycol ester.

The primer is sprayed at a thickness of 15 to 20 microns onto an aluminum sheet with a po227004 coil train. After a short venting time, the wet varnish is sprayed on to a thickness of about 30 to 40 microns and baked for 15 minutes at 135 ° C for 20 minutes.

Prior to application, the percentages (based on the varnish resin) of the polyaylpiperidine compound listed in column 2 (numbered according to the examples mentioned in the description) are always added to the topcoat in column 1.

After 4 weeks of storage in an air-conditioned room (23 ° C / 50 ° / ° C relative air humidity), the coated sheets are subjected to weathering according to ASTM G-53/77 test method in a QUV-tester for 930 hours. they are moistened at 50 ° C for hours and are irradiated in ultraviolet rays at 60 ° C for 4 hours.

Weathered lacquer samples are evaluated according to the TNO Type 353 crack formation scale, comparing the crack pattern to standard samples. Capital letters indicate the shape and size of the cracks. The digits indicate the cracking intensity. To determine the cracking intensity of 10 degrees; the highest intensity level is always denoted by 10. The small letters indicate the crack depth:

and denotes surface damage to the cover layer, b and c means the formation of cracks in the cover layer, or in both the cover and the backing layer;

Column 3 of Table I is always characterized by the crack pattern.

TABLE I

% Polyalkylpiperidine compound The image of cracks _ J 8 a 1 Compound 1 no cracks 1 Compound 3 J 2 a 1 Compound 4 J 3 a 1 Compound 11 no cracks 1 Compound 19 no cracks 1 Compound 20 no cracks 1 Compound 67 no cracks 1 Compound 70 no cracks 1 Compound 75 no cracks

Comparative test

Effective metallic paints based on a binder system containing an alkyd resin containing as an anti-ultraviolet light absorber

The procedure is as in Example 1, except that a UV absorber is used instead of the polyaalkylpiperidine compound. In Table II, column I shows the amount of light-retardant in% (based on the varnish resin), column 2 used the light-retardant and column 3 the image of the cracks.

TABLE II

% Light-retardant Picture (cracks 1 2- (2-Hydroxy-3,5-di-tert-amylphenyl) benzotriazole J 10 p 3 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzothiazole J 9 b 1 2- (2,4-dihydroxyphenyl) benztriazole J 9 b 3 2- (2,4-dihydroxyphenyl benztriazole) J 4 a 1 2,4-dihydroxybenzopheinone J 7a 3 2,4-dihydroxybenzophenoin J 2 a 1 2-Hydroxy-4-octylbenzophenone J 8 p 3 2-hydr, oxy-4-octylbenzophenone J 7 a 1 2-Hydroxy-4-octadecylbenzo- phenon J 9 a 3I 2-hydroxy-4-dodecylbenzo- phenon J 9 b 1 2- (2-Hydroxy-5-isooctylphenyl) benzotriazole J 4 a 3 2- (2-hydroxy-5-isooctyiphenyl) benzotriazole J 2 a 1 2-ethyl-2‘-ethyloxanilide J 4 b 3 2-ethoxy-2'-ethyloxanilide J7b

Example 2

Combination of polyalkylpiperidine derivatives and ultraviolet ray absorbers to stabilize two-layer effect metallic paints (cracking test) based on a binder system containing alkyd resin

An impressive metallic-look lacquer is formed and tested in the manner described in Example 1, with the sole exception that an ultraviolet ray absorber is also incorporated with the polyalkylpiperidine derivative. The following Table III shows in column 1 the amount of the light-protection agent in% (relative to the varnish resin), the light-protective agent used in column 2 and the crack image in column 3.

TABLE III

% Light-retardant Picture cracking 0.5 Compound 1 J 1 a 0.5 2- (2-hydroxy-3,5-di-tert-amylphenyl) benztriazole 0.5 Compound 20 none Cracks 0.5 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole 0.5 Compound 67 none Cracks 0.5 2- (2-Hydroxy-5-a-methylstyrylphenyl) benzothiazole

Example 3

Combination of polyalkylpiperidine derivatives with a metal compound to stabilize a bilayer effect lacquer with a metallic appearance (cracking test) based on a binder system containing an alkyd resin

An impressive anchor-like lacquer was formed and tested as described in Example 1, with the sole exception that a metal salt was incorporated with the polyalkylpiperidine derivative. In the following Table IV, the amount of light-protective agent or metal compound in% (based on the lacquer resin) is in column 1, the light-protective agent and metal compound is used in column 2 and the image of cracks is in column 3.

TABLE IV% Light Cracking Image, Metal Compound

0.5 Compound 11

0.2 nickel acetylacetoinate

0.5 Compound 11

0.2 acetylacetonate aluminum no cracks no cracks

Example 4

An effective metallic-look lacquer is formed and tested as described in Example 1, with the sole exception that an ultraviolet absorber and a metal compound are incorporated with the polyalkylpiperidine derivative. To

0.5% of compound 11 is added

0.5% 2-hydroxy-3,5-di-tert-amylphenylbenzotriazole a

0.2% aluminum acetylacitonate (the percentages refer to the lacquer resin j.

No cracking is observed after weathering. Example 5

Light stabilization of two-layer effect lacquer with metallic appearance (gloss retention test) based on a binder system containing acrylic resin

Basic paint recipe a)

Primer with metallic look Parts

Polyester resin L 1850 (Dynamit Nobel AG) 27.0

Maprenal RT melamine resin (Farbwerke Hochst AG) 3.0

Cellulose Acetobutyrate CAB 531 (Eastman Chem. Corp.) 2.0

Alcoa 726 (Aluminum Corp. of America j 8.0

Toluene 10,0

Xylene 7.0

Butanol 3,0

Buityl acetate 25.0

Aromatic solvent

Solvesso 150 (Essoj 15.0 units)

Unpigmented topcoat

Synthacryl SC 303 (HOchst j 59.0

Maprenal MF 590 (Hochst) 17.4

Butyl glycol acetate 2.0

Solvesso 150 (Essaj 2.0

Solvesso 100 (Essoj 2.0

Xylene 6.6

Silicone oil AL / 1% in xylene 0.2

A 0.4 mm · aluminum sheet is first coated with a commercial primer (reactive paint) and commercial filler and baked, and a primer coated with an aluminum pigment of about 15 microns is applied and unpigmented 30 to 40 microns of topcoat still on the wet backing After a short exhausting time, it is baked in a paint drier for 30 minutes at a temperature of 125 [deg.] C. Two samples are produced, the first without stabilizer, the second with 1% of the stabilizer (based on the varnish resin), which is compound 11, in the topcoat The sheets thus obtained are stored for 4 weeks in a normal climate (23 [deg.] C., 5% relative humidity air and then subjected to a weather test in a QUV according to ASTM G 53-77 The diagram in Fig. 1 shows the dependence of weathering time on the gloss value (ASTM D 523) stabilized with 1% of Compound 11 (O) or unstabilized (X) sample, respectively.

Example 6

Light stabilization of two-layer effect lacquer with metallic appearance on the basis of hot-crosslinking polyacrylic resin containing styrene polymerized

Basic recipe of paint and parts

Primer with metal look

Polyester resin L 1850 (Dynamit Nobel AG) 27.0

Maprenal RT melamine resin (Farbwerke Hochst) 3.0

Cellulose Acetobutyrate CAB 531 (Eastman Chem, Corp. 2.0)

Alcoa 726 (Aluminum Corp.).

of America) 8.0

Toluene 10,0

Xylene 7.0

Butanol 3,0

Butyl acetate 25.0

Solvesso aromatic solvent (Essoj 15.0

b) Parts

Unpigmented topcoat

Commercial acrylic resin containing polymerized styrene (60%) 59.0

Maprenal MF 590 (Hochst) 17.4

Butyl glycol acetate 2.0

Solvesso 150 (Essoj 2.0

Solvesso 100 (Essoj 2.0

Xylene 6.6

Silicone oil OL / 1% in xylene 0.2

The primer was sprayed at a thickness of about 15 microns onto a coil-coated aluminum sheet and then sprayed with a non-pigmented topcoat at a thickness of about 30 to 40 microns onto the still wet substrate. After a short venting time, the lacquers are baked in a paint dryer for 30 minutes at 140 ^° C. The sheets thus obtained are stored in a normal climate for four weeks (23 ° C / 50% relative humidity) and then subjected to an exposure test. weather conditions in a QUV apparatus according to ASTM G 53-77 as described in Example 1.

For the unpigmented coating layer, the amount in column 2 of the light-retardant mentioned is given in column 1 in column 1 of column 1, in each case. , cracking.

TABLE V

% Light-retardant Weather duration (hours) The image of cracks _ - 1400 J 10 p 1 Compound 11 2800 no cracks 0.5 Compound 11 0.5 2- (2-hydroxy-3,5-di-tert- 2800 no cracks

-amylphenyl) benztriazole

Comparative test

Effective lacquers with metallic appearance on the basis of hot-crosslinkable polyacrylic resin containing styrene-polymerized stabilized by UV absorber

The comparative test is carried out exactly as described in Example 6, except that an ultraviolet ray absorber is used instead of the polyalkylpiperidine compound. In Table 1 below, the amount of the light-protection agent in percent (based on the varnish resin) is given in column 1, the light-protection agent used in column 2, the hours of weathering in column 3 and the crack pattern in column 4.

TABLE VI Light-retardant Weather duration (hours) The image of cracks

1400 J 10 p

2,4-dihydroxybenzophenone 2800 J 10 a

2- (2-hydroxy-3,5-di-tert-2800) 10 a

(amylphenyl) benztriazole

It is clear from Table V that the addition of the polyalkylpiperidine compound as a stabilizer alone at twice the exposure time prevents the formation of cracks in the QUV apparatus, unlike when the compound is not present in the sample. This surprisingly good stabilizing effect is not achieved with comparably tested ultraviolet ray absorbers, as shown in Table VI.

The following diagrams in Figures 2 and 3 show that the combination of a polyalkylpiperidine compound with an ultraviolet ray absorber achieves a synergistic stabilizing effect that results in significantly better gloss retention (according to ASTM D 523) and significantly less weight loss. Meaning of the symbols on the diagrams:

No additive, χ 1%. 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, □ 1% of compound 11, • 0,5% of compound 11 + 0,5% 2- (2-hydroxy-3,5-di-tert-butyl) (amylphenyl) benztriazole.

Example 7

Light stabilization of single-layer effect varnish (gloss retention test) based on a binder system containing acrylic resin

Basic Paint Recipe Parts

Aluminum paste Mobil R, fine (Eckhart-Werke, Furth / Bay, DJ 1,29)

Xylene 1.29 Synthacryl SC 300 55% (Hochstj 59.35)

Basic Paint Recipe Parts

Maprenal MF 650, 55% (Cassela-Hochst) 25.22

Polysolfan O (HOchst) 3.97

Ethylene glycol acetate 1.98

Xylene 6.90

The 29.7 parts DKH synthetic resin diluent (Dr. K. Herberts, Wuppertal, D) was set to spray viscosity 19 s according to DIN 53211.

On a 0.4 mra aluminum sheet, a commercial primer (reactive primer) and a commercial filler are first applied and fired and a primer coated with an aluminum pigment is applied in three intersecting directions, vented for 15 minutes. After a period of venting for 20 minutes, the lacquer is baked in a paint dryer for 25 minutes at 120 ° C.

Prior to application, the indicated percentage (based on the varnish resin) of column 2 of said stabilizer (polyalkylpiperidine compound with the number according to the examples given in the description) is added to the lacquer in column 1 of the following Table VII. The sheets thus obtained are stored for 4 weeks in a normalized environment (23 ° C / 5% relative humidity) and then subjected to a weather test in a QUV apparatus according to ASTM G 53-77. The following Table VII shows the dependence of the gloss values obtained (according to ASTM D 523) on the time of weathering (before weathering, p.o 350, 480 and 570 hours).

TABLE VII% Means for protecting the 20 ° gloss after exposure to light for hours

(+420) 350 480 570

- - 70 25 19 Dec 17 1 Compound 3 76 64 57 47 1 Compound 11 75 60 55 52 1 0.5 compound 19 compound 11 75 63 51 48 0.5 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole 75 60 59 59 0.5 0.5 Compound 19 2- (2-hydroxy-3-α-methylbenzyl-5-methylphenyl) benztriazole 77 70 71 71

227

Similar results are also obtained when polyalkylpiperidine derivatives are used in combination with 2- (2-hydroxy-3,5-di-α, N-dimethylbenzylphenyl) benztriazole or 2- [2-hydroxy-3,5-di- 1,3,3-tetramethylbutylphenyl)] benztriazole.

Example 8

Adding adjustable light-proofing agents

Light stabilization of a metallic-look two-layer effect varnish (gloss retention test) with compound A of the formula

Incorporation of compound A into the unpigmented topcoat

A commercial clear melamine-formaldehyde resin crosslinkable acrylic resin lacquer containing polymerized acrylic acid in addition to acrylic acid esters of styrene is mixed with compound A and stirred overnight at 40 ° C.

4

In this case, the light-protective agent ^{1 is} incorporated by reacting the carbohydrate group of the light-protective agent with the acid groups of the acrylic resin. Optionally other light-protective agents may then be added (see Table VIII, column 2 below).

Preparation of test samples

The topcoat, prepared as described above, is wet-sprayed onto an aluminum sheet to which a commercial reactive primer and filler and a metallic effect base lacquer have been pre-applied and baked for 30 minutes at 130 ° C. . The thickness of the undercoat layer is about 15 microns, the thickness of the topcoat layer is about 35 microns.

Tests of weather effects

The plate is left to stand for two weeks in a standardized environment and then tested according to ASTM G 53-77 on a QUV for 1000 hours.

To the unpigmented topcoat, the percentage (based on the varnish resin) indicated in column 1 of the light-retarding agent in column 2 is added in each case. the measured values are given in column 3 of Table VIII.

TABLE VIII

% Light-retardant 20 ° gloss before exposure weather conditions (1000 hours) after weathering (1000 hours) _ _ 98 43 1 Compound A 96 80 0.5 Compound A 99 92 0.5 2- (2-hydroxy-3,5-di-α, α-dime- thylbenzylphenyls 1) benzotriazole 1 Compound A 1 2- (2-hydroxy-3,5-di-α, α-dime- 99 98

thylbenzylphenyl) benzotriazole

Example 9

Polymerization of built-in light protection devices

Light stabilization of a two-layer metallic effect lacquer with a compound of formula B

Incorporation of compound B into the unpigmented topcoat

The compound of formula B is incorporated in an acrylic resin (acrylic ester / styrene copolymer) at a concentration of about 30% by weight (based on the varnish resin) using a compound of formula B in addition to other methacrylic acid and styrene esters as k-omonomers, The solution is introduced into boiling xylene and the polymerization is started with di-tert-butyl peroxide, the reaction time is about 4 hours, and the acrylic resin thus produced is used as a stabilizer with a concentrate for the topcoat. with other light-protective agents (see Table IX) it adds to the commercial clear lacquer (acrylic / melamine resin mixtures).

Preparation of test samples

The topcoat prepared as described above is wet-sprayed onto an aluminum sheet, which is pre-coated with a commercial reactive primer and filler and a metallic effect base lacquer and baked for 30 minutes at 130 ^° C. The thickness of the undercoat layer is about 15 microns, the thickness of the topcoat layer is about 35 microns.

Tests of weather effects

The sheet is left to stand for two weeks in a normalized environment and then treated in Xenotest 1200 by weathering and the time to cracking is determined.

In the non-pigmented topcoat, in each case, in column 1 of Table IX, a percentage (based on the varnish resin) of that amount in column 2 of the light-protecting agent is added. Column 3 shows the hours in hours required for cracking.

TABLE IX

Composition Cracking%, against light exposure after

2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole

0.5 Compound B 0.5 2- (2-hydroxy-3,5-di-tert-amylphenyl) benztriazo-1

1300 hours 1600 hours

1900 hours

Claims (3)

CLAIMS 1. A method for stabilizing single-layer or double-layer baking enamels comprising, as a binder, hot-crosslinkable alkyd or acrylic resin and pigmented with a metal pigment, against light, in particular effect paints with a metallic appearance based on hot-crosslinkable polya. - acrylate resins containing polymers of styrene and, in particular, automotive coatings, characterized in that from 0.01 to 5% by weight of binder are added to the lacquer as a stabilizer. nostních common compounds of formula I containing a group CH3 _ / CH. / ^J “V CH _a (H The invention or an acid addition salt thereof or a metal complex of such a compound. 2. A method according to claim 1, wherein an additional light-retardant is used in an amount selected such that the sum of all light-retardants is 0.02 to 5 percent by weight of the solvent-free binder. lacquer resin. 3. A method according to claim 1, characterized in that antioxidants, plasticizers, flow control agents, curing accelerators, thickeners, dispersants or adhesion promoters are used as further additives.