Method for light stabilization of two-layer uni-lacquer coatings

The use of 2,2,6,6-tetraalkylpiperidine compounds or their acid addition salts or complexes with metal compounds, if desired together with further stabilizers, for stabilizing two-layer uni-lacquer coatings based on thermocrosslinkable acrylic, alkyd or polyester resins, which if desired can be crosslinked with melamine/formaldehyde resins, epoxide resins or polyisocyanates, against the action of light, humidity and oxygen. The stabilization indicated in this specification is particularly suitable for lacquer coatings on cars.

The present invention relates to the stabilization, by the addition of 
polyalkylpiperidine derivatives, of two-layer uni-lacquer coatings based 
on acrylic, alkyd and polyester resins, against the action of light and 
humidity, and also to the lacquers stabilized in this way. 
It is already known from the two Japanese Patent Applications Sho 52-132050 
and Sho 53-60942 that two-layer uni-lacquer coatings can be stabilized 
with conventional UV-absorbers. However, if good stabilization is to be 
ensured, these stabilizers must be used in relatively high concentrations 
and, moreover, in most cases they do not possess the desired lack of color 
which, because of the frequently varying layer thicknesses of the clear 
lacquers, is of extremely great importance in practice. 
Typical degradation phenomena in two-layer lacquer coatings, especially 
crazing, blistering and delamination should, according to experience, best 
be prevented by UV-absorbers. However, it has now been found, 
surprisingly, that when light stabilizers based on polyalkylpiperidine 
derivatives are used excellent stabilization is achieved, even in 
considerably smaller concentrations, despite the lack of absorption in the 
near-UV range. Moreover, the requisite lack of colour is ensured by the 
polyalkylpiperidine derivatives. 
The present invention therefore relates to the use of 
2,2,6,6-tetraalkylpiperidine compounds or their acid addition salts or 
complexes with metal compounds, if desired together with further 
stabilizers, for stabilizing two-layer uni-lacquer coatings based on 
acrylic, alkyd or polyester resins, which, if desired, can be crosslinked 
with melamine/formaldehyde resins, epoxide resins or polyisocyanates, 
against the action of light, humidity and oxygen. 
The 2,2,6,6-tetraalkylpiperidine compounds to be used according to the 
invention are generally known and are already employed against light 
degradation. They are preferably compounds which contain a group of the 
formula (I) 
##STR1## 
in which R is hydrogen or methyl. 
The light stabilizers to be used according to the invention include, in 
particular, the following compound categories: 
(a) Light stabilizers of the formula (II) 
##STR2## 
in which n is the numbers 1-4 and preferably 1 or 2, T is hydrogen or 
--CONH.sub.2, R is as defined under formula (I), R.sub.1 is hydrogen, 
oxyl, C.sub.1 -C.sub.18 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 
alkynyl, C.sub.7 -C.sub.12 aralkyl, C.sub.1 -C.sub.8 alkanoyl, C.sub.3 
-C.sub.5 alkenoyl, glycidyl or a group --CH.sub.2 CH(OH)--Z, in which Z is 
hydrogen, methyl, ethyl or phenyl, and R.sub.1 is preferably hydrogen, 
C.sub.1 -C.sub.12 alkyl, allyl, benzyl, acetyl or acryloyl and R.sub.2, if 
n=1, is hydrogen, C.sub.1 -C.sub.18 alkyl, which can be interrupted by one 
or more oxygen atoms, cyanoethyl, benzyl, glycidyl, a monovalent radical 
of an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic 
carboxylic acid, carbamic acid or phosphorus-containing acid or a 
monovalent silyl radical, preferably a radical of an aliphatic carboxylic 
acid having 2-18 C atoms, of a cycloaliphatic carboxylic acid having 5-12 
C atoms or of an aromatic carboxylic acid having 7-15 C atoms, if n=2 is 
C.sub.1 -C.sub.12 alkylene, C.sub.4 -C.sub.12 alkenylene, xylylene, a 
divalent radical of an aliphatic, cycloaliphatic, araliphatic, aromatic or 
heterocyclic dicarboxylic acid, dicarbamic acid or phosphorus-containing 
acid or a divalent silyl radical, preferably a radical of an aliphatic 
dicarboxylic acid having 2-36 C atoms, of a cycloaliphatic or aromatic 
dicarboxylic acid having 8-14 C atoms or of an aliphatic, cycloaliphatic 
or aromatic dicarbamic acid having 8-14 C atoms, if n=3 is a trivalent 
radical of an aliphatic, cycloaliphatic, aromatic or heterocyclic 
tricarboxylic acid, of an aromatic tricarbamic acid or of a 
phosphorus-containing acid or a trivalent silyl radical and if n=4, is a 
tetravalent radical of an aliphatic, cycloaliphatic or aromatic 
tetracarboxylic acid. 
Any C.sub.1 -C.sub.12 alkyl substituents are, for example, methyl, ethyl, 
n-propyl, n-butyl, sec.-butyl, tert.-butyl, n-hexyl, n-octyl, 
2-ethyl-hexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl. 
C.sub.1 -C.sub.18 Alkyl R.sub.1 or R.sub.2 can be, for example, the groups 
listed above and, in addition, also, for example, n-tridecyl, 
n-tetradecyl, n-hexadecyl or n-octadecyl. 
C.sub.3 -C.sub.8 Alkenyl R.sub.1 can be, for example, 1-propenyl, allyl, 
methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl or 
4-tert.-butyl-2-butenyl. 
C.sub.3 -C.sub.8 Alkynyl R.sub.1 is preferably propargyl. 
C.sub.7 -C.sub.12 Aralkyl R.sub.1 is especially phenethyl or in particular 
benzyl. 
C.sub.1 -C.sub.8 Alkanoyl R.sub.1 is, for example, formyl, propionyl, 
butyryl or octanoyl, but preferably acetyl, and C.sub.3 -C.sub.5 alkenoyl 
R.sub.1 is especially acryloyl. 
As a monovalent radical of a carboxylic acid, R.sub.2 is, for example, the 
radical of acetic acid, stearic acid, salicylic acid, methacrylic acid, 
maleic acid, benzoic acid or 
.beta.-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionic acid. 
As a divalent radical of a dicarboxylic acid, R.sub.2 is, for example, the 
radical of adipic acid, suberic acid, sebacic acid, phthalic acid, 
dibutylmalonic acid, dibenzylmalonic acid, 
butyl-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonic acid or 
bicycloheptenedicarboxylic acid. 
As a trivalent radical of a tricarboxylic acid, R.sub.2 is, for example, 
the radical of trimellitic acid or of nitrilotriacetic acid. 
R.sub.2 can also be radicals of di- and tri-carboxylic acids such as are 
prepared industrially by oligomerisation of higher molecular weight 
unsaturated fatty acids or by a Diels-Alder addition of acrylic acid onto 
linoleic acid. R.sub.2 can also be radicals which are formed by reacting 
mono-, di- and poly-epoxides, for example bisphenol A diglycidyl ether, 
butanediol diglycidyl ether, tris-glycidyl isocyanurate or 
1,3-diglycidyl-4,4-dimethyl-hydantoin, with 
4-hydroxy-1,2,2,6,6-pentamethylpiperidine. 
As a tetravalent radical of a tetracarboxylic acid, R.sub.2 is, for 
example, a pyromellitic acid radical. 
As a divalent radical of a dicarbamic acid, R.sub.2 is, for example, the 
radical of hexamethylenedicarbamic acid or of 2,4-toluylene-dicarbamic 
acid. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(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-salicyloyloxy-2,2,6,6-tetramethylpiperidine 
(7) 4-Methacryloyloxy-1,2,2,6,6-pentamethylpiperidine 
(8) 1,2,2,6,6-Pentamethylpiperidin-4-yl 
.beta.-(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-diethyl-piperidin-4-yl) sebacate 
(13) Di-1-allyl-(2,2,6,6-tetramethyl-piperidin-4-yl) phthalate 
(14) 1-Propargyl-4-.beta.-cyanoethyloxy-2,2,6,6-tetramethylpiperidine 
(15) 1-Acetyl-2,2,6,6-tetramethylpiperidin-4-yl acetate 
(16) Tri-(2,2,6,6-tetramethylpiperidin-4-yl) trimellitate 
(17) 1-Acryloyl-4-benzoyloxy-2,2,6,6-tetramethylpiperidine 
(18) Di-(1,2,2,6,6-pentamethylpiperidin-4-yl) dibutylmalonate 
(19) Di-(1,2,2,6,6-pentamethylpiperidin-4-yl) 
butyl-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate 
(20) Di-(1,2,2,6,6-pentamethylpiperidin-4-yl) dibenzylmalonate 
(21) Di-(1,2,3,6-tetramethyl-2,6-diethyl-piperidin-4-yl) dibenzyl-malonate 
(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-tetramethylpiperidin-4-oxy) silane 
(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) Bis-(1,2,2,6,6-pentamethylpiperidin-4-yl) phenylphosphonate 
(29) Di-(1,2,2,6,6-pentamethylpiperidin-4-yl) sebacate 
(30) Di-(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate 
(31) Di-(1-allyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate 
(31a) 2,2,6,6-Tetramethyl-4-hydroxy-4-carbamoyl-piperidine. 
(b) Light stabilizers of the formula (III) 
##STR3## 
in which n is the number 1 or 2, R is as defined under formula I, R.sub.1 
is as defined under (a), R.sub.3 is hydrogen, C.sub.1 -C.sub.12 alkyl, 
C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.8 aralkyl, C.sub.2 -C.sub.18 
alkanoyl, C.sub.3 -C.sub.5 alkenoyl or benzoyl and R.sub.4, if n=1, is 
hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 
-C.sub.8 alkenyl, which is unsubstituted or substituted by a cyano, 
alkoxycarbonyl or carbamide group, glycidyl or a group of the formula 
--CH.sub.2 --CH(OH)--Z" or of the formula --CONH--Z", in which Z" is 
hydrogen, methyl or phenyl; and if n=2 is C.sub.2 -C.sub.12 alkylene, 
C.sub.6 -C.sub.12 arylene, xylylene, a --CH.sub.2 -CH(OH)--CH.sub.2 group 
or a group --CH.sub.2 --CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 
CH(OH)--CH.sub.2 --, in which x is C.sub.2 -C.sub.10 alkylene, C.sub.6 
-C.sub.15 arylene or C.sub.6 -C.sub.12 cycloalkylene, or, with the proviso 
that R.sub.3 is not alkanoyl, alkenoyl or benzoyl, R.sub.4 can also be a 
divalent radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic 
acid or dicarbamic acid or the group --CO--, or R.sub.3 and R.sub.4 
together, if n=1, can be the imide radical of an aliphatic, cycloaliphatic 
or aromatic 1,2- or 1,3-dicarboxylic acid. 
Any C.sub.1 -C.sub.18 alkyl substituents are as already defined under (a). 
Any C.sub.5 -C.sub.7 cycloalkyl substituents are in particular cyclohexyl. 
C.sub.7 -C.sub.8 Aralkyl R.sub.3 is especially phenethyl or in particular 
benzyl. 
C.sub.2 -C.sub.18 Alkanoyl R.sub.3 is, for example, propionyl, butyryl, 
octanoyl, dodecanoyl, hexadecanoyl or octadecanoyl, but preferably acetyl, 
and C.sub.3 -C.sub.5 alkenoyl R.sub.3 is especially acryloyl. 
As C.sub.2 -C.sub.8 alkenyl which is unsubstituted or substituted by a 
cyano, carbonyl or carbamide group, R.sub.4 is, for example, 1-propenyl, 
allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl, 
2,2-dicyanovinyl, 1-methyl-2-cyano-2-methoxycarbonyl-vinyl or 
2,2-diacetylaminovinyl. 
Any C.sub.2 -C.sub.12 alkylene substituents are, for example, ethylene, 
propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, 
octamethylene, decamethylene or dodecamethylene. 
Any C.sub.6 -C.sub.15 arylene substituents are, for example, o-, m- or 
p-phenylene, 1,4-naphthylene or 4,4'-diphenylene. 
C.sub.6 -C.sub.12 Cycloalkylene X is in particular cyclohexylene. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(32) N,N'-Bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diamine 
(33) 
N,N'-Bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diacetamide 
(34) 1-Acetyl-4-(N-cyclohexylacetamido)-2,2,6,6-tetramethylpiperidine 
(35) 4-Benzylamino-2,2,6,6-tetramethylpiperidine 
(36) N,N'-Bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dibutyl-adipamide 
(37) 
N,N'-Bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dicyclohexyl-(2-hydroxyp 
ropylene) 
(38) N,N'-Bis-(2,2,6,6-tetramethylpiperidin-4-yl)-p-xylylene-diamine 
(39) The compound of the formula 
##STR4## 
(40) 4-(Bis-2-hydroxyethyl)-amino-1,2,2,6,6-pentamethylpiperidine (41) 
4-(3-Methyl-4-hydroxy-5-tert.-butyl-benzoic acid 
amido)-2,2,6,6-tetramethylpiperidine 
(42) 4-Methacrylamido-1,2,2,6,6-pentamethylpiperidine 
(43) Methyl 
.alpha.-cyano-.beta.-methyl-[N-(2,2,6,6-tetramethylpiperidin-4-yl)]-amino- 
acrylate. 
(c) Light stablizers of the formula (IV) 
##STR5## 
in which n is the number 1 or 2, R is as defined under formula (I), 
R.sub.1 is as defined under (a) and R.sub.5, if n=1, is C.sub.2 -C.sub.8 
alkylene or hydroxyalkylene or C.sub.4 -C.sub.22 acyloxyalkylene and, if 
n=2, is the group (--CH.sub.2).sub.2 C(CH.sub.2 --).sub.2. 
C.sub.2 -C.sub.8 Alkylene or hydroxyalkylene R.sub.5 is, for example, 
ethylene, 1-methyl-ethylene, propylene, 2-ethyl-propylene or 
2-ethyl-2-hydroxymethylpropylene. 
C.sub.4 -C.sub.22 Acyloxyalkylene R.sub.5 is, for example, 
2-ethyl-2-acetoxymethyl-propylene. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(44) 9-Aza-8,8,10,10-tetramethyl-1,5-dioxaspiro[5.5]undecane 
(45) 9-Aza-8,8,10,10-tetramethyl-3-ethyl-1,5-dioxaspiro[5.5]decane 
(46) 8-Aza-2,7,7,8,9,9-hexamethyl-1,4-dioxaspiro[4.5]decane 
(47) 
9-Aza-3-hydroxymethyl-3-ethyl-8,8,9,10,10-pentamethyl-1,5-dioxaspiro[5.5]u 
ndecane 
(48) 
9-Aza-3-ethyl-3-acetoxymethyl-9-acetyl-8,8,10,10-tetramethyl-1,5-dioxaspir 
o[5.5]undecane 
(49) 
2,2,6,6-Tetramethylpiperidine-4-spiro-2'-(1',3'-dioxan)-5'-spiro-5"-(1",3" 
-dioxan)-2"-spiro-4'''-(2''',2''',6''',6'''-tetramethylpiperidine). 
(d) Light stabilizers of the formulae (VA), (VB) and (VC) 
##STR6## 
in which n is the number 1 or 2, R is as defined under formula (I), 
R.sub.1 is as defined under (a), R.sub.6 is hydrogen, C.sub.1 -C.sub.12 
alkyl, allyl, benzyl, glycidyl or C.sub.2 -C.sub.6 alkoxyalkyl and 
R.sub.7, if n=1, is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.5 
alkenyl, C.sub.7 -C.sub.9 aralkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 
-C.sub.4 hydroxyalkyl, C.sub.2 -C.sub.6 alkoxyalkyl, C.sub.6 -C.sub.10 
aryl, glycidyl or a group of the formula --(CH.sub.2).sub.m --COO--Q or of 
the formula --(CH.sub.2).sub.m --O--CO--Q, in which m is 1 or 2 and Q is 
C.sub.1 -C.sub.18 alkyl or phenyl, and if n=2 is C.sub.2 -C.sub.12 
alkylene, C.sub.6 -C.sub.12 arylene, C.sub.4 -C.sub.12 alkenylene, a group 
--CH.sub.2 --CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 --CH(OH)--CH.sub.2 --, 
in which X is C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 arylene or 
C.sub.6 -C.sub.12 cycloalkylene, or a group --CH.sub.2 CH(OZ')CH.sub.2 
-(OCH.sub.2 --CH(OZ')CH.sub.2).sub.2 --, in which Z' is hydrogen, C.sub.1 
-C.sub.18 alkyl, allyl, benzyl, C.sub.2 -C.sub.12 alkanoyl or benzoyl, and 
T.sub.1 and T.sub.2 independently of one another are hydrogen, C.sub.1 
-C.sub.18 alkyl or C.sub.6 -C.sub.10 aryl which is unsubstituted or 
substituted by halogen or C.sub.1 -C.sub.4 alkyl, or C.sub.7 -C.sub.9 
aralkyl, or T.sub.1 and T.sub.2 together with the C atom which bonds them 
form C.sub.5 -C.sub.7 cycloalkyl, pyrrolidinyl or piperidinyl, which are 
unsubstituted or substituted by C.sub.1 -C.sub.4 alkyl. 
Any C.sub.1 -C.sub.12 alkyl substituents are, for example, methyl, ethyl, 
n-propyl, n-butyl, sec.-butyl, tert.-butyl, n-hexyl, n-octyl, 
2-ethyl-hexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl. 
Any C.sub.1 -C.sub.18 alkyl substituents can be, for example, the groups 
listed above and, in addition, also, for example, n-tridecyl, 
n-tetradecyl, n-hexadecyl or n-octadecyl. 
Any C.sub.2 -C.sub.6 alkoxyalkyl substituents are, for example, 
methoxymethyl, ethoxymethyl, propoxymethyl, tert.-butoxymethyl, 
ethoxyethyl, ethoxypropyl, n-butoxyethyl, tert.-butoxyethyl, 
isopropoxyethyl or propoxypropyl. 
C.sub.3 -C.sub.5 Alkenyl R.sub.7 is, for example, 1-propenyl, allyl, 
methallyl, 2-butenyl or 2-pentenyl. 
C.sub.7 -C.sub.9 Aralkyl R.sub.7, T.sub.1 and T.sub.2 is especially 
phenethyl or in particular benzyl, and C.sub.5 -C.sub.7 cycloalkyl 
R.sub.7, T.sub.1 and T.sub.2 (T.sub.1 and T.sub.2 together with the C atom 
which bonds them) is in particular cyclohexyl. 
C.sub.2 -C.sub.4 Hydroxyalkyl R.sub.7 is, for example, 2-hydroxyethyl, 
2-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl. 
C.sub.6 -C.sub.10 Aryl R.sub.7, T.sub.1 and T.sub.2 is especially phenyl or 
.alpha.- or .beta.-naphthyl, which are unsubstituted or substituted by 
halogen or C.sub.1 -C.sub.4 alkyl. 
C.sub.2 -C.sub.12 alkylene R.sub.7 is, for example, ethylene, propylene, 
2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, 
decamethylene or dodecamethylene. 
C.sub.4 -C.sub.12 Alkenylene R.sub.7 is especially 2-butenylene, 
2-pentenylene or 3-hexenylene. 
C.sub.6 -C.sub.12 Arylene R.sub.7 is, for example, o-, m- or p-phenylene, 
1,4-naphthylene or 4,4'-diphenylene. 
C.sub.2 -C.sub.12 Alkanoyl Z' is, for example, propionyl, butyryl, octanoyl 
or dodecanoyl but preferably acetyl. 
C.sub.2 -C.sub.10 Alkylene, C.sub.6 -C.sub.15 arylene or C.sub.6 -C.sub.12 
cycloalkylene X is as defined under (b). 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(50) 3-Benzyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione 
(51) 3-n-Octyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione 
(52) 3-Allyl-1,3,8-triaza-1,7,7,9,9-pentamethylspiro[4.5]decane-2,4-dione 
(53) 
3-Glycidyl-1,3,8-triaza-7,7,8,9,9-pentamethylspiro[4.5]decane-2,4-dione 
(53a) 
2-iso-Propyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4.5]decane 
(53b) 2-Butyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane 
(53c) 2-Isopropyl-7,7,9,9-tetramethyl-1-oxa-4,8-diaza-3-oxospiro[4.5]decane 
(53d) 2-Butyl-7,7,9,9-tetramethyl-1-oxa-4,8-diaza-3-oxospiro[4.5]decane 
or the compounds of the following formulae: 
##STR7## 
(e) Light stabilizers of the formula (VI) 
##STR8## 
in which n is the number 1 or 2 and R.sub.8 is a group of the formula 
##STR9## 
in which R is as defined under formula (I), R.sub.1 is as defined under 
(a), Y is --O-- or --NR.sub.11 --, A is C.sub.2 -C.sub.6 alkylene or 
--(CH.sub.2).sub.3 --O-- and p is the numbers 0 or 1, R.sub.9 is the 
groups R.sub.8, NR.sub.11 R.sub.12, --OR.sub.13, --NHCH.sub.2 OR.sub.13 or 
--N(CH.sub.2 OR.sub.13).sub.2, and R.sub.10, if n=1, is the groups R.sub.8 
or R.sub.9, and if n=2, is the group --Y--D--Y--, in which D is C.sub.2 
-C.sub.6 alkylene which can be interrupted by --N(R.sub.11)--, and 
R.sub.11 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, benzyl or C.sub.1 
-C.sub.4 hydroxyalkyl or a group of the formula 
##STR10## 
R.sub.12 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, benzyl or C.sub.1 
-C.sub.4 hydroxyalkyl, R.sub.13 is hydrogen, C.sub.1 -C.sub.12 alkyl or 
phenyl and R.sub.14 is hydrogen, C.sub.1 -C.sub.12 alkyl, cyclohexyl, 
benzyl or phenyl, or R.sub.11 and R.sub.12 together are C.sub.4 -C.sub.5 
alkylene or oxaalkylene, or R.sub.11 and R.sub.12 are each a group of the 
formula 
##STR11## 
Any C.sub.1 -C.sub.12 alkyl substituents are, 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. 
Any C.sub.1 -C.sub.4 hydroxyalkyl substituents are, for example, 
2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 
4-hydroxybutyl. 
C.sub.2 -C.sub.6 Alkylene A is, for example, ethylene, propylene, 
2,2-dimethylpropylene, tetramethylene or hexamethylene. 
C.sub.4 -C.sub.5 Alkylene or oxaalkylene formed by R.sub.11 and R.sub.12 
together is, for example, tetramethylene, pentamethylene or 
3-oxa-pentamethylene. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
compounds of the following formulae: 
##STR12## 
(f) Light stabilizers of the formula (VII) 
##STR13## 
in which n is the number 1 or 2, R is as defined under formula (I) and 
R.sub.14, if n=1, is C.sub.4 -C.sub.18 alkyl, C.sub.7 -C.sub.12 aralkyl, 
the group --CO--R.sub.15 or C.sub.1 -C.sub.4 alkyl substituted by --CN, 
--COOR.sub.16, --OH, --OCOR.sub.17 or 
##STR14## 
in which R.sub.15 is C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.4 alkenyl or 
phenyl, R.sub.16 is C.sub.1 -C.sub.18 alkyl and R.sub.17 is C.sub.1 
-C.sub.18 alkyl, C.sub.2 -C.sub.10 alkenyl, cyclohexyl, benzyl or C.sub.6 
-C.sub.10 aryl, or, if n=2, R.sub.14 is C.sub.4 -C.sub.12 alkylene, 
2-but-1,4-enylene, xylylene, the group --(CH.sub.2).sub.2 --OOC--R.sub.18 
--COO--(CH.sub.2).sub.2 -- or the group --CH.sub.2 --OOC--R.sub.19 
--COO--CH.sub.2 --, in which R.sub.18 is C.sub.2 -C.sub.10 alkylene, 
phenylene or cyclohexylene and R.sub.19 is C.sub.2 -C.sub.10 alkylene, 
xylylene or cyclohexylene. 
Any C.sub.1 -C.sub.12 alkyl substituents are, for example, methyl, ethyl, 
n-propyl, n-butyl, sec.-butyl, tert.-butyl, n-hexyl, n-octyl, 
2-ethyl-hexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl. 
Any C.sub.1 -C.sub.18 alkyl substituents can be, for example, the groups 
listed above and, in addition, also, for example, n-tridecyl, 
n-tetradecyl, n-hexadecyl or n-octadecyl. 
Any C.sub.2 -C.sub.10 alkylene groups are, for example, ethylene, 
propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, 
octamethylene or decamethylene. 
C.sub.4 -C.sub.18 Alkyl R.sub.14 is, for example, n-butyl, sec.-butyl, 
tert.-butyl, n-hexyl, n-octyl, 2-ethyl-hexyl, 
1,1-dimethyl-2-tert.-butylethyl, n-nonyl, n-decyl, n-dodecyl, n-tridecyl, 
n-tetradecyl, n-hexadecyl or n-octadecyl. 
As C.sub.1 -C.sub.4 alkyl substituted by --CN, R.sub.14 is, for example, 
cyanomethyl, cyanoethyl, 3-cyano-n-propyl or 4-cyano-n-butyl. 
C.sub.4 -C.sub.12 Alkylene R.sub.14 is, for example, 2,2-dimethylpropylene, 
tetramethylene, hexamethylene, octamethylene, decamethylene or 
dodecamethylene. 
C.sub.7 -C.sub.12 Aralkyl R.sub.14 is especially phenethyl or 
p-methyl-benzyl or in particular benzyl. 
C.sub.2 -C.sub.4 Alkenyl R.sub.15 is, for example, vinyl, 1-propenyl, 
allyl, methallyl or 2-butenyl. 
C.sub.2 -C.sub.10 Alkenyl R.sub.17 is, for example, the groups listed for 
alkenyl R.sub.15 and, in addition, also, for example, crotyl, 2-hexenyl, 
2-octenyl or 2-decenyl. 
C.sub.6 -C.sub.10 Aryl R.sub.17 is, for example, phenyl which is 
unsubstituted or substituted in the o-position or p-position by methyl, 
ethyl, isopropyl, n-butyl or tert.-butyl. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(64) Bis-[.beta.-(2,2,6,6-tetramethylpiperidino)-ethyl] sebacate 
(65) n-Octyl .alpha.-(2,2,6,6-tetramethyl-piperidino)-acetate 
(66) 1,4-Bis-(2,2,6,6-tetramethylpiperidino)-2-butene. 
(g) Light stabilizers of the formula (VIII) 
##STR15## 
in which B is --N(R.sub.21)-- or --O--, E is C.sub.1 -C.sub.3 alkylene, 
the group --CH.sub.2 --CH(R.sub.22)--O--, in which R.sub.22 is hydrogen, 
methyl or phenyl, the group --(CH.sub.2).sub.3 --NH-- or a single bond, R 
is hydrogen or methyl, R.sub.1 is as defined under a), R.sub.20 is 
hydrogen or C.sub.1 -C.sub.18 alkyl and R.sub.21 is hydrogen, C.sub.1 
-C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.12 aralkyl, 
cyanoethyl, C.sub.6 -C.sub.10 aryl, the group --CH.sub.2 
--CH(R.sub.22)--OH, in which R.sub.22 is as defined above, a group of the 
formula 
##STR16## 
or a group of the formula 
##STR17## 
in which G can be C.sub.2 -C.sub.6 alkylene or C.sub.6 -C.sub.12 arylene, 
or R.sub.21 is a group --E--CO--NH--CH.sub.2 --OR.sub.20. 
Any C.sub.1 -C.sub.18 alkyl substituents are, for example, methyl, ethyl, 
n-propyl, n-butyl, sec.-butyl, tert.-butyl, n-hexyl, n-octyl, 
2-ethyl-hexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, 
n-tetradecyl, n-hexadecyl or n-octadecyl. 
Any C.sub.7 -C.sub.12 aralkyl substituents are, for example, phenethyl or 
especially benzyl. 
C.sub.3 -C.sub.8 Alkenyl R.sub.1 can be, for example, 1-propenyl, allyl, 
methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl or 
4-tert.-butyl-2-butenyl. 
C.sub.3 -C.sub.8 Alkynyl R.sub.1 is preferably propargyl. C.sub.1 -C.sub.8 
Alkanoyl R.sub.1 is, for example, formyl, propionyl, butyryl, or octanoyl, 
but preferably acetyl, and C.sub.3 -C.sub.5 akenoyl R.sub.1 is in 
particular acryloyl. 
C.sub.5 -C.sub.7 Cycloalkyl R.sub.21 is in particular cyclohexyl. 
C.sub.6 -C.sub.10 Aryl R.sub.21 is in particular phenyl or .alpha.- or 
.beta.-naphthyl, which are unsubstituted or substituted by halogen or 
C.sub.1 -C.sub.4 alkyl. C.sub.1 -C.sub.3 Alkylene E is, for example, 
methylene, ethylene or propylene. 
C.sub.2 -C.sub.6 Alkylene G is, for example, ethylene, propylene, 
2,2-dimethylpropylene, tetramethylene or hexamethylene and C.sub.6 
-C.sub.12 arylene G is o-, m- or p-phenylene, 1,4-naphthylene or 
4,4'-diphenylene. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
following compounds: 
(67) N-Hydroxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea 
(68) N-Methoxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea 
(69) N-Methoxymethyl-N'-n-dodecyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea 
(70) O-(2,2,6,6-Tetramethylpiperidin-4-yl)-N-methoxymethyl-urethane. 
(h) Polymeric compounds in which the recurring structural unit contains a 
polyalkylpiperidine radical of the formula (I), especially polyesters, 
polyethers, polyamides, polyamines, polyurethanes, polyureas, 
polyaminotriazines, poly(meth)acrylates, poly(meth)acrylamides and their 
copolymers which contain such radicals. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
compounds of the following formulae, in which m is the numbers 2 to about 
200. 
##STR18## 
(i) Compounds which contain, in their molecule, at least one 
2-(2'-hydroxyphenyl)-benztriazole group or 2-hydroxybenzophenone group and 
at least one polyalkylpiperidine group. 
Examples of polyalkylpiperidine light stabilizers of this category are the 
compounds of the following formulae: 
##STR19## 
It is also possible to use polyalkylpiperidine derivatives of categories 
(a)-(i) which enter into chemical bonds with the binder of the lacquer. 
This is the case if the polyalkylpiperidine derivative possesses a 
reactive group suitable for this purpose, for example a glycidyl group or 
a methylol group. 
Examples of such compounds are the polyalkylpiperidine derivatives of 
category (g) which contain methylol groups or methylol-ether groups. 
If the polyalkylpiperidine compounds are basic compounds, they can form 
salts with acids. Suitable acids for this purpose are, for example, 
inorganic acids or organic carboxylic, sulfonic, phosphonic or phosphinic 
acids, for example hydrochloric acid, boric acid, phosphoric acid, acetic 
acid, salicylic acid, toluenesulfonic acid or benzenephosphonic acid. 
The polyalkylpiperidine compounds can form complexes with complex-forming 
metal compounds, for example with zinc-II acetate, cobalt-II 
acetylacetonate, nickel-II acetylacetonate, aluminium-III acetylacetonate, 
nickel-II benzoate or aluminum-III benzoylacetonate. 
The customary stoving lacquers which are based on acrylic, alkyd or 
polyester resins, which, if desired, can be crosslinked with 
melamine/formaldehyde resins, epoxide resins or polyisocyanates, and which 
are described, for example in H. Wagner and H. F. Sarx, Lackkunstharze 
(Synthetic Lacquer Resins) can be used to prepare the two-layer 
uni-lacquer coatings stabilized according to the invention against light, 
humidity and oxygen. 
The lacquers are applied by the conventional twocoat process, for example 
by spraying the undercoat lacquer containing the pigment in a layer 
thickness of 20-30.mu. onto coil-coated sheet metal, onto which a 
commercially available filler had previously been baked in a layer 
thickness of 20-30.mu., and, after air-drying for about 5 minutes, 
applying the topcoat lacquer wet-in-wet in a layer thickness of 35-40.mu.. 
After further air-drying for about 15 minutes, the lacquer is baked at 
80.degree.-150.degree. C., depending on the nature of the crosslinking 
agent, for about 30 minutes. 
The amount of polyalkylpiperidine derivative added is 0.01 to 5% by weight, 
based on the solvent-free binder, and preferably 0.5 to 1% by weight. The 
lacquers can contain the customary organic solvents or can be dissolved or 
dispersed in water or can be free from solvent. 
The polyalkylpiperidine derivative to be used for stabilization according 
to the invention can be incorporated either only into the unpigmented 
topcoat lacquer or both into the unpigmented topcoat lacquer and into the 
undercoat lacquer containing pigment. Preferably, the light stabilizer is 
incorporated in the unpigmented topcoat lacquer. Topcoat lacquers based on 
acrylic/melamine resins are preferred. When preparing acrylic resins or 
acrylic-modified alkyd resins, polymerisable polyalkylpiperidine 
derivatives (for example compounds 7 and 42) can be copolymerised in the 
resin. 
Incorporation into the lacquer binder can, however, also be effected by a 
polycondensation reaction during the preparation or in some cases during 
baking of the melamine, alkyd or polyester resins. Examples of 
co-condensable polyalkylpiperidine derivatives are compounds 1 and 63 and 
also 1-hydroxyethyl-4-hydroxy-2,2,6,6-tetramethylpiperidine or the 
compounds of the formulae 
##STR20## 
Incorporation by a polyaddition reaction can take place, for example, via 
the reaction of free carboxyl groups in the acrylic resin with glycidyl 
groups of the polyalkylpipeidine derivative. These carboxyl groups can be 
incorporated, for example, by the copolymerisation of acrylic acid. 
In these cases there is the additional advantage that the light stabilizers 
are not removable by extraction or migration, so that their action is very 
longlasting. 
In order to achieve maximum stability to light, it can be advantageous 
additionally to use other conventional light stabilizers. Examples of 
these are UV-absorbers of the type comprising the benzophenones, 
oxalanilides, benztriazoles or acrylic acid derivatives, or 
metal-containing light stabilizers, for example organic nickel compounds. 
In the case of such combinations, the sum of all of the light stabilisers 
is 0.02 to 5% by weight and preferably 0.5 to 2% by weight, based on the 
lacquer resin. 
Further additives which can be contained in the lacquer are antioxidants, 
for example those of the type comprising sterically hindered phenol 
derivatives or organic phosphorus compounds, for example phosphites, 
phosphonites or phosphines, plasticizers, flow control agents, curing 
accelerators, for example organic Co salts, Mn salts or Zr salts, 
thickeners, dispersing agents or adhesion improvers. 
The stabilization according to the invention is particularly suitable for 
lacquer coatings on vehicles.

The following examples describe the use, according to the invention, of 
polyalkylpiperidine derivatives in two-layer uni-lacquer coatings. Parts 
and percentages are by weight. 
EXAMPLE 1 
Basic recipe for the lacquers 
______________________________________ 
(a) Undercoat lacquer 
______________________________________ 
Alftalat AC 451 51.56 parts 
(alkyd resin from Hochst) 
Maprenal MF 590 20.7 parts 
(melamine/formaldehyde resin from 
Hochst) 
TiO.sub.2 27.6 parts 
C.I. Pigment Yellow 24 0.14 part 
______________________________________ 
dissolved in a solvent mixture consisting of 44% of xylene, 26% of 
petroleum ether and 30% of butyl acetate. 
______________________________________ 
(b) Topcoat lacquer 
______________________________________ 
Viacryl VC 1341/60% 62.5 parts 
(acrylic resin from Vianova Kunstharz 
AG) 
in Shellsol A/butyl acetate 
Maprenal MF 825/71% 17.6 parts 
(melamine/formaldehyde resin from 
Hochst) 
in isobutanol 
Solvesso 100 19.4 parts 
(solvent from Esso) 
Paint Additive 11 0.5 part 
(flow control agent from Dow Corning Corp.) 
______________________________________ 
Production of the two-layer uni-lacquer coating 
A commercially available filler (Standox filling primer) is first sprayed 
in a layer thickness of 30.mu. onto coil-coated sheet aluminium and is 
baked for 15 minutes at 175.degree. C. The pigmented undercoat lacquer is 
then sprayed on in a layer thickness of about 30.mu. and, after air-drying 
for 5 minutes, the unpigmented topcoat lacquer is applied wet-in-wet in a 
layer thickness of 35-40.mu.. The lacquer is then baked for 30 minutes at 
130.degree. C. 
Weathering 
The metal sheets thus obtained are stored for four weeks under standard 
climatic conditions (23.degree. C./50% relative atmospheric humidity) and 
then subjected to weathering in a QUV apparatus according to ASTM G53-77. 
When the tests described below were carried out, the light stabilizer 
indicated in column II of the tables 1, 2 and 3 given below (the 
stabilisers being numbered in accordance with the examples mentioned in 
the description in the case of the polyalkylpiperidine compounds to be 
used according to the invention) was added, in each case in the amount 
indicated in % (based on the lacquer resin) in column I of the said 
tables, to the topcoat lacquer before the latter was applied. 
Yellowing test after weathering for 1,200 hours 
The change in the blue-yellow value (.DELTA. BYV) is a measure of the 
yellowing of the lacquers. It is determined by calculation from the 
photometrically determined colour coordinates. The corresponding values 
are listed in column III of Tables 1, 2 and 3 given below. 
Reduction in gloss after weathering for 1,200 hours 
The gloss values determined after weathering for 1,200 hours and in 
accordane with ASTM D 523 are listed in column IV of Tables 1, 2 and 3 
given below. 
Visual appearance of the lacquer-coated metal sheets after weathering for 
1,200 hours 
After weathering, the metal sheets were examined for cloudiness, crazing, 
blistering and delamination. The findings are listed in column V of Tables 
1, 2 and 3 given below. 
TABLE 1 
__________________________________________________________________________ 
Light stabilizing action of the polyalkylpiperidine derivatives 
IV 
III 20.degree. gloss after 
V 
.DELTA. BYV after 
weathering (QUV) 
Appearance after 
I II weathering (QUV) 
1,200 
weathering (QUV) 
% Light stabilizer 
for 1,200 hours 
0 hours 
hours 
for 1,200 hours 
__________________________________________________________________________ 
-- 
-- 16 97 16 crazing and blistering 
and delamination 
1 Compound 11 
8.7 99 94 isolated blistering 
1 Compound 19 
9.3 98 91 isolated blistering 
1 Compound 53 
9.5 97 93 no change 
1 Compound 82 
8.8 93 80 no change 
1 Compound 83 
9.5 98 90 no change 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Light stablilizing action in the case of the combination of polyalkyl- 
piperidine compounds and UV-absorbers 
IV 
III 20.degree. gloss after 
V 
.DELTA. BYV after 
weathering (QUV) 
Appearance after 
I II weathering (QUV) 
1,200 
weathering (QUV) 
% Light stabilizer 
for 1,200 hours 
0 hours 
hours 
for 1,200 hours 
__________________________________________________________________________ 
-- 
-- 16 97 16 crazing, blistering 
and delamination 
0.5 
Compound 11 
0.5 
2-(2-Hydroxy-3,5-di- 
6.2 99 93 no change 
tert.-amyl-phenyl)- 
benztriazole 
0.5 
Compound 29 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha., .alpha.- 
7.2 97 91 no change 
dimethylbenzyl)-phenyl]- 
benztriazole 
0.5 
Compound 53 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha., .alpha.- 
6.4 98 91 no change 
dimethylbenzyl)-phenyl]- 
benztriazole 
0.5 
Compound 80 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha.,.alpha.- 
7.9 92 79 no change 
dimethylbenzyl)-phenyl]- 
benztriazole 
0.5 
Compound 63 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha.,.alpha.- 
7.6 97 88 no change 
dimethylbenzyl)-phenyl]- 
benztriazole 
0.5 
Compound 30 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha.,.alpha.- 
7.6 97 82 no change 
benztriazole 
0.5 
Compound 31 
0.5 
2-[2-Hydroxy-3,5-di-(.alpha.,.alpha. - 
8.0 97 86 no change 
dimethylbenzyl)-phenyl]- 
benztriazole 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
IV 
III 20.degree. gloss after 
V 
.DELTA. BYV after 
weathering (QUV) 
Appearance after 
I II weathering (QUV) 
1,200 
weathering (QUV) 
% Light stabilizer 
for 1,200 hours 
0 hours 
hours 
for 1,200 hours 
__________________________________________________________________________ 
-- 
-- 16 97 16 crazing and blistering 
and delamination 
1 2-(2-Hydroxy-3,5-di- 
12.5 97 53 cloudy, 
tert.-amyl-phenyl)- extensive blistering 
benztriazole 
2 2-Hydroxy-4-dodecyloxy- 
9.5 99 87 cloudy, crazing 
benzophenone 
2 2,4-Dihydroxy-benzo- 
9.4 99 26 cloudy, crazing 
phenone 
2 2,2'-Dihydroxy-4,4'- 
10.6 99 36 cloudy, crazing 
dimethoxy-benzophenone 
__________________________________________________________________________