Lubricant formulations - Patent Review 5167844

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The invention relates to lubricant formulations that are stabilised against oxidative degradation. The stabilisation is effected by the addition of at least three specific additives to the lubricant.

It is known to add additives to lubricants, such as mineral oils or synthetic and semi-synthetic oils, in order to improve properties in use.

Great importance is attached to additives that inhibit the oxidative degradation of the lubricants and ensure a high degree of storage stability and consistency of action.

In particular, the thermo-oxidative requirement profile of modern motor oils has changed as a result of new engine designs in the field of internal combustion engines having self-ignition or spark ignition. In engines having spark ignition, for example, present-day engine layouts and operating methods result in the increased formation of nitrogen oxides which, in turn, pass into the crankcase as "blow-by" gases.

In addition, the lubricating oil in the upper piston ring and cylinder region provides the fine sealing with respect to the combustion chamber. Here contamination with high boiling fuel components can occur. These given conditions are aggravated by the presence of NO.sub.x.

The blow-by gases, which contain increasingly high proportions of NO.sub.x, then result in the lubricating oil's having a greater susceptibility to oxidation, and "sludge nuclei" are formed which finally result in undesirable sludge deposits which have become known as "black sludge".

It is to be assumed that NO.sub.x -initiated auto-oxidation of the lubricating oil is involved.

There has been no lack of attempts to improve lubricating oils by the addition of anti-oxidants.

An additional difficulty lies in the fact that attempts are being made at least partly to eliminate heavy metals from the lubricant additives on ecological and technical grounds. In particular, efforts are being made today at least partly to replace the highly effective additive zinc dialkyl dithiophosphate, which is found in many lubricants, in order to reduce the heavy metal content in the lubricant. The reduced heavy metal content in the lubricant has a positive effect on the service life of the exhaust catalysts now being mounted in the exhaust gas flow of petroleum engines (Auto, Motor und Sport, Vol. 13, June 16, 1989, pages 70-72).

For example, in engines with self-ignition, such as diesel engines, as a result of the smaller amounts of oil in the lubrication system and the higher operating temperatures, as are demanded today, the lubricating oil is subjected to greater frictional stress at a higher operating temperature. Under such conditions known lubricating oils have an increased tendency towards an undesirable thickening and increase in viscosity.

Mineral lubricating oil mixtures and especially steam turbine oils having improved stability are disclosed, for example, in DE-AS 1 594 405. Steam turbine oils are described that contain an aliphatic carboxylic acid having at least 12 carbon atoms, an alkylphenol, an aromatic amine and a dialkyl dithiophosphate. Alkali metal salts of dialkyl thiophosphates are mentioned, but only the zinc dialkyl dithiophosphates are preferred and used in the practical examples.

EP-A-239 536 discloses lubricant formulations that contain in a mineral lubricating oil a phenolic and/or an aminic anti-oxidant in addition to a metal deactivator of the azole type and a hydroxyalkylalkanolamine corrosion inhibitor.

It has now been found that a mixture of at least three additives allows the use of alkali metal dialkyl dithiophosphates in lubricants, the anti-oxidant action surprisingly being improved while, at the same time, such lubricant formulations exhibit a remarkably good performance. The formulations according to the invention are able in particular to prevent or reduce the thickening of the oil that occurs under frictional stress at relatively high temperature.

The subject of the invention is a formulation containing

A) a lubricant and a mixture of

B) at least one compound of general formula I ##STR2##

wherein X, X.sup.1 and X.sup.2, each independently of the others, are oxygen or sulfur; or X.sup.2 is ##STR3## in which r is 1 or 2 and Ry is --H or --CH.sub.3 ; wherein R.sup.x is C.sub.1 -C.sub.24 alkyl or is C.sub.2 -C.sub.12 alkyl that is interrupted by --O--, --S-- and/or --C(O)O--; unsubstituted or C.sub.1 -C.sub.12 alkyl-substituted phenyl; C.sub.5 -C.sub.12 cycloalkyl or C.sub.5 -C.sub.12 cycloalkyl that is substituted by C.sub.1 -C.sub.4 alkyl; or C.sub.7 -C.sub.13 aralkyl or C.sub.7 -C.sub.13 aralkyl that is interrupted in the alkyl radical by --O-- or --S--; a is 1 or 2, and in the case where a is 2, the radicals R.sup.x are identical or different or two radicals R.sup.x, together with the two hetero atoms X.sup.1 and the P atom to which they are bonded, form a 5- or 6-membered ring by means of a dimethylene or trimethylene group or by means of a dimethylene or trimethylene group that is substituted by at least one C.sub.1 -C.sub.4 alkyl group; and wherein M.sup..sym. is an alkali metal cation, with the proviso that when a is 1, two different M.sup..sym. are possible,

C) at least one compound from the series of the aromatic amines of formulae II and III ##STR4## wherein R.sup.1 is C.sub.1 -C.sub.18 alkyl, C.sub.7 -C.sub.9 phenylalkyl, C.sub.5 -C.sub.12 cycloalkyl, phenyl, C.sub.7 -C.sub.18 alkylphenyl, C.sub.7 -C.sub.18 alkoxyphenyl or naphthyl,

R.sup.2 is phenyl, C.sub.7 -C.sub.18 alkylphenyl, C.sub.7 -C.sub.18 alkoxyphenyl or naphthyl,

R.sup.3 is hydrogen, C.sub.1 -C.sub.12 alkyl, benzyl, allyl, methallyl, phenyl or a group --CH.sub.2 SR.sup.g wherein R.sup.g is --H, alkyl having from 1 to 8 carbon atoms, phenyl or cycloalkyl having from 5 to 12 carbon atoms,

R.sup.a is H, C.sub.1 -C.sub.18 alkyl, --CH.sub.2 COO(C.sub.4 -C.sub.18 alkyl) or --CH.sub.2 CH.sub.2 COO(C.sub.4 -C.sub.18 alkyl), and

R.sup.b and R.sup.c, each independently of the other, are --H, C.sub.1 -C.sub.18 alkyl or C.sub.7 -C.sub.9 phenylalkyl, and

D) at least one compound from the series of the cyclic sterically hindered amines, the acyclic sterically hindered amines and the phenols of general formula V ##STR5## wherein R.sup.4 is H, alkyl having from 1 to 24 carbon atoms, cycloalkyl having from 5 to 12 carbon atoms, C.sub.1 -C.sub.4 alkyl-substituted cycloalkyl having from 5 to 12 carbon atoms, phenyl or --CH.sub.2 --S--R.sup.10,

R.sup.5 is alkyl having from 1 to 24 carbon atoms, cycloalkyl having from 5 to 12 carbon atoms, C.sub.1 -C.sub.4 alkyl-substituted cycloalkyl having from 5 to 12 carbon atoms, phenyl or --CH.sub.2 --S--R.sup.10, and

A is --H, alkyl having from 1 to 24 carbon atoms, --C.sub.q H.sub.2q --N(R') (R"), --C.sub.q H.sub.2q --S.sub.z --Y, ##STR6## and Y is --H, alkyl having from 1 to 18 carbon atoms, phenyl, C.sub.1 -C.sub.24 alkyl-substituted phenyl, benzyl, ##STR7## or, when q is 0, ##STR8## wherein R.sup.4 and R.sup.5 are each as defined above, R' and R" are identical or different and are --H or C.sub.1 -C.sub.24 alkyl, and

f is 1 or 2,

d is 0, 1, 2 or 3,

q is 0, 1, 2 or 3,

z is 1, 2, 3 or 4,

R.sup.6 is C.sub.1 -C.sub.24 alkyl,

R.sup.7 is alkyl having from 1 to 24 carbon atoms, ##STR9## wherein d is in each case 0, 1, 2 or 3 and t is 2, 3, 4, 5 or 6, and wherein R.sup.4 and R.sup.5 are each as defined above, and

R.sup.8 and R.sup.9, each independently of the other, are H, alkyl having from 1 to 12 carbon atoms, phenyl or phenyl substituted by one or two C.sub.1 -C.sub.4 alkyl groups and/or --OH, or

R.sup.8 and R.sup.9 together with the carbon atom linking them form a C.sub.5 -C.sub.12 cycloalkyl group, and

R.sup.10 is C.sub.1 -C.sub.18 alkyl, phenyl or ##STR10## wherein f and R.sup.6 are as defined above.

Accordingly, the formulation according to the invention is a lubricant that contains at least one ternary mixture as anti-oxidant additive.

The definitions of R.sup.x, M.sup..sym., X, X.sup.1, X.sup.2, a and b in compounds of general formula I have, for example, the following meanings.

When R.sup.x is C.sub.1 -C.sub.24 alkyl, it includes straight-chain or branched alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, 2-methylpropyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, hexadecyl, heptadecyl, octadecyl or eicosyl. Radicals containing from 3 to 12 carbon atoms are preferred, and radicals containing from 3 to 8 carbon atoms are especially preferred.

When R.sup.x is C.sub.2 -C.sub.12 alkyl interrupted by --O--, --S-- or --C(O)O--, the hetero atom or the --C(O)O-- group can be in any of the possible positions, and the C.sub.2 -C.sub.12 alkyl radical can be interrupted one or more times by identical or different hetero atoms as well as by --C(O)O-- groups. One interruption is preferred.

When R.sup.x is C.sub.1 -C.sub.12 alkyl-substituted phenyl, the phenyl radical can be mono- or poly-substituted, but preferably mono- or di-substituted; C.sub.1 -C.sub.12 alkyl is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, straight-chain or branched nonyl or dodecyl. Monosubstituted phenyl is preferred, the alkyl radical advantageously containing from 3 to 12 carbon atoms and preferably from 8 to 12 carbon atoms. Nonylphenyl is especially advantageous.

When R.sup.x is C.sub.5 -C.sub.12 cycloalkyl, it includes, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl, preferably cyclohexyl.

When R.sup.x is C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.12 cycloalkyl, it may be mono- or poly-substituted, but is preferably monosubstituted, and may be, for example, methylcyclohexyl, trimethylcyclohexyl, butylcyclohexyl or propylcyclopentyl.

When R.sup.x is C.sub.7 -C.sub.13 aralkyl, it includes, for example, benzyl, 1- or 2-phenethyl, 3-phenylpropyl, .alpha.,.alpha.-dimethylbenzyl, 2-phenylisopropyl, 2-phenylhexyl, benzhydryl and naphthylmethyl, but preferably benzyl.

When R.sup.x is C.sub.7 -C.sub.13 aralkyl interrupted in the alkyl radical by --O-- or --S--, a typical example thereof is a phenoxyethyl group.

When two radicals R.sup.x, together with the two hetero atoms X.sup.1 and the P atom to which they are bonded, form a 5- or 6-membered ring by means of a dimethylene or trimethylene group that is substituted by at least one C.sub.1 -C.sub.4 alkyl group, then the dimethylene or trimethylene group advantageously carries one, two or three alkyl groups having 1, 2, 3 or 4 carbon atoms and preferably one or two alkyl groups having 1, 2 or 4 carbon atoms.

M.sup..sym. is an alkali metal cation, for example Li.sup..sym., Na.sup..sym., K.sup..sym. or Rb.sup..sym.. Preferred metal cations M.sup..sym. are Na.sup..sym. and K.sup..sym..

An advantageous embodiment comprises formulations wherein in the compounds of formula I R.sup.x is C.sub.1 -C.sub.12 alkyl optionally interrupted by --O--, --S-- or --C(O)O--, or unsubstituted or C.sub.1 -C.sub.12 alkyl-substituted, especially C.sub.8 -C.sub.12 alkyl-substituted, phenyl; cyclohexyl or benzyl, R.sup.x preferably being C.sub.3 -C.sub.12 alkyl optionally interrupted by --C(O)O--, or phenyl or nonylphenyl.

Also of interest are formulations wherein in the compounds of formula I X is oxygen, and also those wherein in the compounds of formula I X.sup.1 and X.sup.2 are oxygen, or those wherein in the compounds of formula I X and X.sup.2 are sulfur and X.sup.1 is oxygen.

Formulations wherein in the compounds of formula I M.sup..sym. Na.sup..sym. are of further interest.

Formulations wherein in the compounds of formula I X is sulfur, and also those wherein in the compounds of formula I X is sulfur and X.sup.1 and X.sup.2 are oxygen; or those wherein in the compounds of formula I X is sulfur, X.sup.1 is oxygen and X.sup.2 is sulfur, are of additional interest.

Formulations wherein in the compounds of formula I X is sulfur, X.sup.1 is oxygen, X.sup.2 is sulfur or oxygen, R.sup.x is C.sub.3 -C.sub.8 alkyl or C.sub.8 -C.sub.12 alkyl-substituted phenyl, a is 2, b is 1 and M.sup..sym. is Na.sup..sym. or K.sup..sym., are of particular interest. M can be especially sodium.

When X.sup.2 is, for example, ##STR11## then R.sup.y is --H or --CH.sub.3 and r is 1 or 2. Especially preferred groups are, for example, --S--CH.sub.2 --COO.sup..sym. --, --O--CH.sub.2 --COO.sup..sym. --, --S--CH.sub.2 --CH.sub.2 --COO.sup..sym. --, --O--CH.sub.2 --CH.sub.2 --COO.sup..sym. --, ##STR12##

The following compounds are of very special interest: O,O-bis-nonylphenylsodium dithiophosphate, O,O-bis-nonylphenylsodium thionophosphate, O,O-bis-2-ethylhexylsodium dithiophosphate, O,O-dibutylsodium dithiophosphate, O,O-dicyclohexylsodium dithiophosphate, O,O-di-n-octylpotassium thionophosphate, O,O-di-isononyllithium dithiophosphate, O,O-diethylsodium dithiophosphate, O,O-bis-dodecylphenylsodium dithiophosphate, O,O-dipentylsodium dithiophosphate, O,O-bis-2-ethylhexylsodium thionophosphate, O,O-dipropylpotassium dithiophosphate, O,O-bis-2-methylpropylsodium dithiophosphate, O,O-di-isodecylpotassium thionophosphate, S-[O,O-di-n-dodecylphosphoryl]-potassium thioglycolate, 2-potassiummercapto-2-thiono-5,5-dimethyl-[1,3,2]-dioxaphosphorinane, 2-sodiummercapto-2-oxo-5-butyl-5-ethyl-[1,3,2]-dioxaphosphorinane, O,O-dibenzylpotassium dithiophosphate, S-[2-thiono-5,5-dimethyl-[1,3,2]-dioxaphosphorinanyl]-.beta.-mercaptolithi um propionate, O,O-bis-1-methylethylsodium dithiophosphate, O-ethyl-O-1-methylpropylsodium dithiophosphate, O,O-bis-2-phenoxyethylsodium dithiophosphate, O,O-bis-dodecylphenylsodium thionophosphate, O,O-bis-1-methylpropylsodium dithiophosphate, O,O-bis-2-butoxyethyllithium dithiophosphate, O-tridecyl-O-pentadecylpotassium dithiophosphate, O,O-bis-isopropylphenylsodium dithiophosphate, O,O-bis-2-butylthioethylsodium dithiophosphate, S-[O,O-bis-2-ethylhexylthiophosphoryl]-sodium thioglycolate, S-[O,O-bis-2-ethylhexylphosphoryl]-potassium thioglycolate, S-[O,O-diisopropylthiophosphoryl]-.beta.-mercaptolithium propionate, S-[O,O-dipentylthiophosphoryl]-3-mercapto-2-methyllithium propionate, O,O-bis-2-decyltetradecylpotassium dithiophosphate.

The meanings of the substituents in compounds of formulae II and III, and advantageous and preferred compounds of formulae II and III, are given by way of example below.

R.sup.3 as C.sub.1 -C.sub.12 alkyl can be linear or branched alkyl and can be, for example, methyl, ethyl, propyl, n-butyl, tert.-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, nonyl, decyl or dodecyl. R.sup.1, R.sup.a, R.sup.b and R.sup.c as C.sub.1 -C.sub.18 alkyl can also be, for example, tetradecyl, pentadecyl, hexadecyl or octadecyl. R.sup.a can advantageously be C.sub.4 -C.sub.18 alkyl, for example n-butyl, tert.-butyl, n-hexyl, 2-ethylhexyl, nonyl, n-dodecyl or octadecyl.

R.sup.1, R.sup.b and R.sup.c as C.sub.7 -C.sub.9 phenylakyl can be, for example, benzyl, 2-phenylethyl, .alpha.-methylbenzyl, 2-phenylpropyl or .alpha.,.alpha.-dimethylbenzyl.

R.sup.1 and R.sup.g as cycloalkyl having from 5 to 12 carbon atoms are, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl. Cyclohexyl is preferred. R.sup.1 and R.sup.2 as C.sub.7 -C.sub.18 alkylphenyl can be mono- or poly-substituted phenyl having linear or branched alkyl groups. Phenyl radicals substituted by one or two alkyl groups are advantageous. Examples are tolyl, ethylphenyl, isopropylphenyl, tert.-butylphenyl, sec.-pentylphenyl, n-hexylphenyl, tert.-octylphenyl, isononylphenyl and n-dodecylphenyl. R.sup.1 and R.sup.2 may also be mixtures of alkylphenyl groups, as are formed in industrial alkylations of diphenylamine by means of olefins. The alkyl group is preferably in the para-position of the aromatic amine.

When R.sup.1 and R.sup.2 are C.sub.7 -C.sub.18 alkoxyphenyl, examples thereof are methoxyphenyl and ethoxyphenyl.

It is preferable to use as component C) a compound of formula II or III wherein

R.sup.1 is C.sub.1 -C.sub.4 alkyl, C.sub.7 -C.sub.9 phenylalkyl, cyclohexyl, phenyl, C.sub.10 -C.sub.18 alkylphenyl or naphthyl,

R.sup.2 is C.sub.10 -C.sub.18 alkylphenyl or phenyl,

R.sup.3 is hydrogen, C.sub.1 -C.sub.8 alkyl, benzyl, allyl or a group --CH.sub.2 SR.sup.g wherein R.sup.g is --H, C.sub.1 -C.sub.4 alkyl, phenyl or cyclohexyl,

R.sup.a is H, C.sub.1 -C.sub.18 alkyl or --CH.sub.2 COO(C.sub.8 -C.sub.18 alkyl), and

R.sup.b and R.sup.c, each independently of the other, are H, C.sub.1 -C.sub.12 alkyl or C.sub.7 -C.sub.9 phenylalkyl.

Further compounds of formula III are those wherein R.sup.a is advantageously C.sub.4 -C.sub.18 alkyl or --CH.sub.2 COO(C.sub.8 -C.sub.18 alkyl).

Especially preferred compounds of formula II are those wherein R.sup.1 and R.sup.2, each independently of the other, are phenyl or C.sub.10 -C.sub.18 alkylphenyl, especially mono- or di-tert.-butylphenyl or tert.-octylphenyl, and R.sup.3 is hydrogen.

Especially preferred compounds of formula III are those wherein R.sup.a is hydrogen and R.sup.b and R.sup.c, each independently of the other, are H or C.sub.4 -C.sub.12 -alkyl. Examples of compounds of formulae II and III are:

diphenylamine,

N-allyldiphenylamine,

4-isopropoxydiphenylamine,

N-phenyl-1-naphthylamine,

N-phenyl-2-naphthylamine,

di-4-methoxyphenylamine,

di-[4-(1,3-dimethylbutyl)-phenyl]-amine,

di-[4-(1,1,3,3-tetramethylbutyl)-phenyl]-amine,

tert.-octylated N-phenyl-1-naphthylamine,

industrial mixtures obtained by alkylation of diphenylamine with alkenes, especially with octenes, for example with diisobutylene (for example mono-, di- and tri-alkylated tert.-butyl- and tert.-octyl-diphenylamines),

phenothiazine,

N-allylphenothiazine,

3,7-di-tert.-octylphenothiazine,

industrial mixtures obtained by alkylation of phenothiazine with alkenes, especially with octenes, for example with diisobutylene.

Especially preferred is the use as component C) of 4,4'-di-tert.-octyldiphenylamine or 3,7-di-tert.-octylphenothiazine or an industrial mixture obtained by reaction of diphenylamine with diisobutylene, especially such a mixture containing the following constituents:

______________________________________ 1 to 5% by weight a) diphenylamine, 8 to 18% by weight b) 4-tert.-butyldiphenylamine, 21 to 31% by weight c) one or more of the compounds i) 4-tert.-octyldiphenylamine, ii) 4,4'-di-tert.-butyldiphenylamine, iii) 2,4,4'-tris-tert.-butyldiphenylamine, 20 to 31% by weight d) one or more of the compounds i) 4-tert.-butyl-4'-tert.-octyldiphenylamine, ii) 2,2'-or 2,4'-di-tert.-octyldiphenylamine, iii) 2,4-di-tert.-butyl-4'-tert.-octyldiphenyl- amine and 15 to 29% by weight e) the compound i) 4,4'-di-tert.-octyldiphenylamine or the compounds i) 4,4'-di-tert.-octyldiphenylamine and ii) 2,4-di-tert.-octyl-4'-tert.-butyldiphenyl- amine. ______________________________________

An especially preferred diphenylamine mixture contains as component C) 3.2% diphenylamine, 13.2% mono-tert.-butyldiphenylamines, 25.3% mono-tert.-octyldiphenylamines and di-tert.-butyldiphenylamines, 24.2% tert.-butyl-tert.-octyldiphenylamines, 24.3% di-tert.-octyldiphenylamines and other higher alkylated diphenylamines, the content of 4,4'-di-tert.-octyldiphenylamine being 18.2%, and further relatively small amounts of diphenylamines having partially modified side chains and polymers to make up to 100%.

Examples of further components C) containing compounds of formulae II and III are:

N-substituted diphenylamines of the general formula ##STR13## wherein R' is methyl, ethyl, propyl or allyl;

a diphenylamine compound of the formula ##STR14##

a diphenylamine compound of the formula ##STR15##

a diphenylamine compound of the formula ##STR16##

a mixture containing diphenylamine compounds of the formulae ##STR17##

a mixture containing diphenylamine compounds of the formulae ##STR18##

a diphenylamine compound of the formula ##STR19##

Component D) can be any cyclic or acyclic sterically hindered amine. D) is preferably a cyclic sterically hindered amine, especially a compound containing at least one group of formula (VI) ##STR20## wherein R is hydrogen or methyl. R is preferably hydrogen. These are derivatives of polyalkylpiperidines, especially of 2,2,6,6-tetramethylpiperidine. These polyalkylpiperidines preferably carry in the 4-position one or two polar substituents or a polar spiro-ring system.

The following classes of polyalkylpiperidines are of particular importance.

a) Compounds of formula VII ##STR21## wherein n is from 1 to 4, preferably 1 or 2, R is hydrogen or methyl, R.sup.11 is hydrogen, oxyl, hydroxy, C.sub.1 -C.sub.12 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.18 alkoxy, C.sub.5 -C.sub.8 cycloalkoxy, C.sub.7 -C.sub.9 phenylalkoxy, C.sub.1 -C.sub.8 alkanoyl, C.sub.3 -C.sub.5 alkenoyl, C.sub.1 -C.sub.18 -alkanoyloxy, benzyloxy, glycidyl or a group --CH.sub.2 CH(OH)--Z wherein Z is hydrogen, methyl or phenyl, R.sup.11 preferably being H, C.sub.1 -C.sub.4 alkyl, allyl, benzyl, acetyl or acryloyl, and when n is 1, R.sup.12 is hydrogen, C.sub.1 -C.sub.18 alkyl optionally interrupted by one or more oxygen atoms, cyanoethyl, benzyl, glycidyl, a monovalent radical of an aliphatic, cycloaliphatic, araliphatic, unsaturated or aromatic carboxylic acid, carbamic acid or phosphorus-containing acid, or is a monovalent silyl radical, preferably a radical of an aliphatic carboxylic acid having from 2 to 18 carbon atoms, a cycloaliphatic carboxylic acid having from 7 to 15 carbon atoms, an .alpha.,.beta.-unsaturated carboxylic acid having from 3 to 5 carbon atoms or an aromatic carboxylic acid having from 7 to 15 carbon atoms, and when n is 2, R.sup.12 is C.sub.1 -C.sub.12 -alkylene, C.sub.4 -C.sub.12 alkenylene, xylylene, a divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, dicarbamic acid or phosphorus-containing acid, or is a divalent silyl radical, preferably a radical of an aliphatic dicarboxylic acid having from 2 to 36 carbon atoms, a cycloaliphatic or aromatic dicarboxylic acid having from 8 to 14 carbon atoms or an aliphatic, cycloaliphatic or aromatic dicarbamic acid having from 8 to 14 carbon atoms, and when n is 3, R.sup.12 is a trivalent radical of an aliphatic, cycloaliphatic or aromatic tricarboxylic acid, and aromatic tricarbamic acid or a phosphorus-containing acid, or is a trivalent silyl radical, and when n is 4, R.sup.12 is a tetravalent radical of an aliphatic, cycloaliphatic or aromatic tetracarboxylic acid.

When any substituents are C.sub.1 -C.sub.12 alkyl, they 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.

R.sup.11 or R.sup.12 as C.sub.1 -C.sub.18 alkyl may be, for example, the groups listed above and in addition, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When R.sup.11 is C.sub.3 -C.sub.8 alkenyl, it may include, for example, 1-propenyl, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl and 4-tert.-butyl-2-butenyl.

R.sup.11 as C.sub.3 -C.sub.8 alkynyl is preferably propargyl.

R.sup.11 as C.sub.7 -C.sub.12 aralkyl is especially phenethyl and more especially benzyl.

R.sup.11 as C.sub.1 -C.sub.8 alkanoyl is, for example, formyl, propionyl, butyryl, octanoyl, but preferably acetyl, and as C.sub.3 -C.sub.5 alkenoyl especially acryloyl.

When R.sup.12 is a monovalent radical of a carboxylic acid, it is, for example, an acetic acid, caproic acid, stearic acid, acrylic acid, methacrylic acid, benzoic acid or .beta.-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid radical.

When R.sup.12 is a divalent radical of a dicarboxylic acid, it is, for example, a malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, maleic acid, itaconic acid, phthalic acid, dibutylmalonic acid, dibenzylmalonic acid, butyl-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonic acid or bicycloheptenedicarboxylic acid radical.

When R.sup.12 is a trivalent radical of a tricarboxylic acid, it is, for example, a trimellitic acid, citric acid or nitrilotriacetic acid radical.

When R.sup.12 is a tetravalent radical of a tetracarboxylic acid, it is, for example, the tetravalent radical of butane-1,2,3,4-tetracarboxylic acid or of pyromellitic acid.

When R.sup.12 is a divalent radical of a dicarbamic acid, it is, for example, a hexamethylenedicarbamic acid or a 2,4-toluylenedicarbamic acid radical.

Compounds of formula VII wherein R is hydrogen, R.sup.11 is hydrogen or methyl, n is 2 and R.sup.12 is the diacyl radical of an aliphatic dicarboxylic acid having from 4 to 12 carbon atoms are preferred.

The following compounds are examples of polyalkylpiperidine compounds of this class:

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-hydroxyph enyl)-propionate

9) di-(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)-maleinate

10) di-(2,2,6,6-tetramethylpiperidin-4-yl)-succinate

11) di-(2,2,6,6-tetramethylpiperidin-4-yl)-glutarate

12) di-(2,2,6,6-tetramethylpiperidin-4-yl)-adipate

13) di-(2,2,6,6-tetramethylpiperidin-4-yl)-sebacate

14) di-(1,2,2,6,6-pentamethylpiperidin-4-yl)-sebacate

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

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

17) 1-hydroxy-4-.beta.-cyanoethyloxy-2,2,6,6-tetramethylpiperidine

18) 1-acetyl-2,2,6,6-tetramethylpiperidin-4-yl acetate

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

20) 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine

21) diethylmalonic acid di-(2,2,6,6-tetramethylpiperidin-4-yl) ester

22) dibutylmalonic acid di-(1,2,2,6,6-pentamethylpiperidin-4-yl) ester

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

24) di-(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)-sebacate

25) di-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)-sebacate

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

27) toluene-2',4'-bis-(4-carbamoyloxy-1-n-propyl-2,2,6,6-tetramethylpiperidine

28) dimethyl-bis-(2,2,6,6-tetramethylpiperidin-4-oxy)-silane

29) phenyl-tris-(2,2,6,6-tetramethylpiperidine-4-oxy)-silane

30) tris-(1-propyl-2,2,6,6-tetramethylpiperidin-4-yl)-phosphite

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

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

33) 4-hydroxy-1,2,2,6,6-pentamethylpiperidine

34) 4-hydroxy-N-hydroxyethyl-2,2,6,6-tetramethylpiperidine

35) 4-hydroxy-N-(2-hydroxypropyl)-2,2,6,6-tetramethylpiperidine

36) 1-glycidyl-4-hydroxy-2,2,6,6-tetramethylpiperidine.

b) Compounds of formula (VIII) ##STR22## wherein n is 1 or 2, R and R.sup.11 are as defined under a), R.sup.13 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.5 hydroxyalkyl, 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, benzoyl, or a group of the formula ##STR23## and when n is 1, R.sup.14 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.1 -C.sub.4 alkyl substituted by a hydroxy, cyano, alkoxycarbonyl or carbamide group, glycidyl, a group of the formula --CH.sub.2 --CH(OH)--Z or the formula --CONH--Z wherein Z is hydrogen, methyl or phenyl; when n is 2, R.sup.14 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--D--O-- wherein D is C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 -arylene or C.sub.6 -C.sub.12 cycloalkylene, or, provided that R.sup.13 is not alkanoyl, alkenoyl or benzoyl, R.sup.14 may also be a divalent radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or dicarbamic acid or alternatively may be the group --CO--, or when n is 1, R.sup.13 and R.sup.14 together can be the divalent radical of an aliphatic, cycloaliphatic or aromatic 1,2- or 1,3-dicarboxylic acid.

When any substituents are C.sub.1 -C.sub.12 alkyl or C.sub.1 -C.sub.18 alkyl, they are as already defined under a).

When any substituents are C.sub.5 -C.sub.7 cycloalkyl, they are especially cyclohexyl.

R.sup.13 as C.sub.7 -C.sub.8 aralkyl is especially phenylethyl or more especially benzyl. R.sup.13 as C.sub.2 -C.sub.5 hydroxyalkyl is especially 2-hydroxyethyl or 2-hydroxypropyl.

R.sup.13 as C.sub.2 -C.sub.18 alkanoyl is, for example, propionyl, butyryl, octanoyl, dodecanoyl, hexadecanoyl, octadecanoyl, but preferably acetyl, and as C.sub.3 -C.sub.5 alkenoyl especially acryloyl.

When R.sup.14 is C.sub.2 -C.sub.8 alkenyl, it is, for example, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl or 2-octenyl.

R.sup.14 as C.sub.1 -C.sub.4 alkyl substituted by a hydroxy, cyano, alkoxycarbonyl or carbamide group may be, for example, 2-hydroxyethyl, 2-hydroxypropyl, 2-cyanoethyl, methoxycarbonylmethyl, 2-ethoxycarbonylethyl, 2-aminocarbonylpropyl or 2-(dimethylaminocarbonyl)-ethyl.

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

When any substituents are C.sub.6 -C.sub.15 arylene, they are, for example, o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.

D as C.sub.6 -C.sub.12 cycloalkylene is especially cyclohexylene.

Preferred compounds of formula VIII are those wherein n is 1 or 2, R is hydrogen, R.sup.11 is hydrogen or methyl, R.sup.13 is hydrogen, C.sub.1 -C.sub.12 alkyl or a group of the formula ##STR24## and when n is 1, R.sup.14 is hydrogen or C.sub.1 -C.sub.12 alkyl and when n is 2, R.sup.14 is C.sub.2 -C.sub.8 alkylene.

The following compounds are examples of polyalkylpiperidine compounds of this class:

37) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diamine, which is regarded as especially preferred, and also

38) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diacetamide

39) bis-(2,2,6,6-tetramethylpiperidin-4-yl)-amine

40) 4-benzoylamino-2,2,6,6-tetramethylpiperidine

41) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dibutyladipamide

42) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dicyclohexyl-2-hydroxypr opylene-1,3-diamine

43) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-p-xylylenediamine

44) N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-succindiamide

45) N-(2,2,6,6-tetramethylpiperidin-4-yl)-.beta.-aminodipropionic acid di-(2,2,6,6-tetramethylpiperidin-4-yl) ester

46) the compound of the formula ##STR25## 47) 4-(bis-2-hydroxyethylamino)-1,2,2,6,6-pentamethylpiperidine 48) 4-(3-methyl-4-hydroxy-5-tert.-butylbenzamido)-2,2,6,6-tetramethylpiperidin e

49) 4-methacrylamido-1,2,2,6,6-pentamethylpiperidine.

c) Compounds of formula (IX) ##STR26## wherein n is 1 or 2, R and R.sup.11 are as defined under a) and when n is 1, R.sup.15 is C.sub.2 -C.sub.8 alkylene, C.sub.2 -C.sub.8 hydroxyalkylene or C.sub.4 -C.sub.22 acyloxyalkylene, and when n is 2, R.sup.15 is the group (--CH.sub.2).sub.2 C(CH.sub.2 --).sub.2.

When R.sup.15 is C.sub.2 -C.sub.8 alkylene or C.sub.2 -C.sub.8 hydroxyalkylene, it is, for example, ethylene, 1-methylethylene, propylene, 2-ethylpropylene or 2-ethyl-2-hydroxymethylpropylene.

R.sup.15 as C.sub.4 -C.sub.22 acyloxyalkylene is, for example, 2-ethyl-2-acetoxymethylpropylene.

The following compounds are examples of polyalkylpiperidine compounds of this class:

50) 9-aza-8,8,10,10-tetramethyl-1,5-dioxaspiro[5.5]undecane

51) 9-aza-8,8,10,10-tetramethyl-3-ethyl-1,5-dioxaspiro[5.5]undecane

52) 8-aza-2,7,7,8,9,9-hexamethyl-1,4-dioxaspiro[4.5]decane

53) 9-aza-3-hydroxymethyl-3-ethyl-8,8,9,10,10-pentamethyl-1,5-dioxaspiro-[5.5] undecane

54) 9-aza-3-ethyl-3-acetoxymethyl-9-acetyl-8,8,10,10-tetramethyl-1,5-dioxaspir o[5.5]undecane

55) 2,2,6,6-tetramethylpiperidine-4-spiro-2'-(1',3'-dioxane)-5'-spiro-5"-(1",3 "-dioxane)-2"-spiro-4"-(2"',2"',6"',6"'-tetramethylpiperidine).

d) Compounds of formulae XA, XB and XC ##STR27## wherein n is 1 or 2, R and R.sup.11 are as defined under a), R.sup.16 is hydrogen, C.sub.1 -C.sub.12 alkyl, allyl, benzyl, glycidyl or C.sub.2 -C.sub.6 alkoxyalkyl and when n is 1, R.sup.17 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.p --COO--Q or the formula --(CH.sub.2).sub.p --O--CO--Q wherein p is 1 or 2 and Q is C.sub.1 -C.sub.4 alkyl or phenyl, and when n is 2, R.sup.17 is C.sub.2 -C.sub.12 alkylene, C.sub.4 -C.sub.12 alkenylene, C.sub.6 -C.sub.12 arylene, a group --CH.sub.2 --CH(OH)--CH.sub.2 --O--D--O--CH.sub.2 --CH(OH)--CH.sub.2 -- wherein D 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 --(OZ')CH.sub.2).sub.2 -- wherein Z' is hydrogen, C.sub.1-C.sub.18 alkyl, allyl, benzyl, C.sub.2 -C.sub.12 alkanoyl or benzoyl, T.sub.1 and T.sub.2, each independently of the other, are hydrogen, C.sub.1 -C.sub.18 alkyl or unsubstituted or halo- or C.sub.1 -C.sub.4 alkyl-substituted C.sub.6 -C.sub.10 aryl or C.sub.7 -C.sub.9 aralkyl, or T.sub.1 and T.sub.2 together with the carbon atom bonding them form a C.sub.5 -C.sub.12 cycloalkane ring.

When any substitutes are C.sub.1 -C.sub.12 alkyl, they 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 substituents C.sub.1 -C.sub.18 alkyl may be, for example, the groups listed above and in addition, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When any substituents are C.sub.2 -C.sub.6 alkoxyalkyl, they are, for example, methoxymethyl, ethoxymethyl, propoxymethyl, tert.-butoxymethyl, ethoxyethyl, ethoxypropyl, n-butoxyethyl, tert.-butoxyethyl, isopropoxyethyl or propoxypropyl.

When R.sup.17 is C.sub.3 -C.sub.5 alkenyl, it is, for example, 1-propenyl, allyl, methallyl, 2-butenyl or 2-pentenyl.

R.sup.17, T.sub.1 and T.sub.2 as C.sub.7 -C.sub.9 aralkyl are especially phenethyl or more especially benzyl. When T.sub.1 and T.sub.2 together with the carbon atom form a cycloalkane ring, this may be, for example, a cyclopentane, cyclohexane, cyclooctane or cyclododecane ring.

When R.sup.17 is C.sub.2 -C.sub.4 hydroxyalkyl, it is, for example, 2-hydroxyethyl, 2-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.

R.sup.17, T.sub.1 and T.sub.2 as C.sub.6 -C.sub.10 aryl are especially phenyl, .alpha.- or .beta.-naphthyl that are unsubstituted or substituted by halogen or C.sub.1 -C.sub.4 alkyl.

When R.sup.17 is C.sub.2 -C.sub.12 alkylene, it is, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.

R.sup.17 as C.sub.4 -C.sub.12 alkenylene is especially 2-butenylene, 2-pentenylene or 3-hexenylene.

When R.sup.17 is C.sub.6 -C.sub.12 arylene, it is, for example, o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.

When Z' is C.sub.2 -C.sub.12 alkanoyl, it is, for example, propionyl, butyryl, octanoyl, dodecanoyl, but preferably acetyl.

D as C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 arylene or C.sub.6 -C.sub.12 cycloalkylene is as defined under b).

The following compounds are examples of polyalkylpiperidine compounds of this class:

56) 3-benzyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione

57) 3-n-octyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione

58) 3-allyl-1,3,8-triaza-1,7,7,9,9-pentamethylspiro[4.5]decane-2,4-dione

59) 3-glycidyl-1,3,8-triaza-7,7,8,9,9-pentamethylspiro[4.5]decane-2,4-dione

60) 1,3,7,7,8,9,9-heptamethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione

61) 2-isopropyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane

62) 2,2-dibutyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane

63) 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-21-oxodispiro[5.1.11.2]-heneicosane

64) 2-butyl-7,7,9,9-tetramethyl-1-oxa-4,8-diaza-3-oxospiro[4.5]decane

65) 8-acetyl-3-dodecyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-di one

or the compounds of the following formulae: ##STR28##

e) Compounds of formula XI ##STR29## wherein n is 1 or 2 and R.sup.18 is a group of the formula ##STR30## wherein R and R.sup.11 are as defined under a), E is --O-- or --NR.sup.11 --, A is C.sub.2 -C.sub.6 alkylene or --(CH.sub.2).sub.3 --O-- and x is 0 or 1, R.sup.19 has the same meaning as R.sup.18 or is one of the groups --NR.sup.21 R.sup.22, --OR.sup.23, --NHCH.sub.2 OR.sup.23 or --N(CH.sub.2 OR.sup.23).sub.2, and when n is 1, R.sup.20 has the same meaning as R.sup.18 or R.sup.19, and when n is 2, R.sup.20 is a group --E--B--E-- wherein B is C.sub.2 -C.sub.6 alkylene optionally interrupted by --N(R.sup.21)--, R.sup.21 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, benzyl or C.sub.1 -C.sub.4 hydroxyalkyl or a group of the formula ##STR31## R.sup.22 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, benzyl or C.sub.1 -C.sub.4 hyroxyalkyl and R.sup.23 is hydrogen, C.sub.1 -C.sub.12 alkyl or phenyl, or R.sup.21 and R.sup.22 together are C.sub.4 -C.sub.5 -alkylene or C.sub.4 -C.sub.5 oxaalkylene, for examp