Polyalkylpiperidine compounds

A polyalkylpiperidine compound of the formula I ##STR32## in which Y is the group ##STR33## R.sup.1 is a hydrogen atom or an alkyl group, R.sup.2 is a group of the formula R.sup.17 --O-- or R.sup.18 --CO-- (acyl),

• R.sup.3 and R.sup.4 are identical or different and are a hydrogen atom or an alkyl group, or R.sup.5 and R.sup.4, together with the carbon atom connecting them, form a ring having 5 to 12 ring members or a group of the formula ##STR34## n is 1, 2 or 3, and A, in the case where n=1, is a hydrogen atom, R.sup.5 --, R.sup.5 --CO--, R.sup.5 --NH--CO-- (urethane), --COOR.sup.5, --P(OR.sup.6) (OR.sup.7), --Si(OR.sup.5) (OR.sup.5) (OR.sup.5), or --SiR.sup.5 R.sup.5 R.sup.5
• A, in the case where n=2, is --R.sup.11 --, --CO--R.sup.12 --CO--, --CO--NH--R.sup.13 --NH--CO--, --CO--, =POR.sup.5, =Si (OR.sup.5) (OR.sup.5), or =SiR.sup.5 R.sup.5
• A, in the case where n=3, is R.sup.14 .ident., R.sup.15 (CO--).sub.3, R.sup.16 (NH--CO--).sub.3, .ident.Si(OR.sup.5), .ident.SiR.sup.5 R.sup.5 is a C.sub.1 -C.sub.18 alkyl group, a C.sub.2 -C.sub.18 -alkenyl group, a C.sub.2 -C.sub.18 -alkynyl group, a C.sub.5 -C.sub.12 -cycloalkyl group, a C.sub.6 -C.sub.10 -bicycloalkyl group, a C.sub.5 -C.sub.8 -cycloalkenyl group, a C.sub.6 -C.sub.10 -aryl group, a C.sub.7 -C.sub.9 aralkyl group, a C.sub.7 -C.sub.9 -alkaryl group, unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl or phenyl, where a plurality of radicals
• R.sup.5 may be identical or different,
• R.sup.6 and R.sup.7 are identical or different and are a C.sub.1 -C.sub.18 -alkyl group, a C.sub.2 -C.sub.18 -alkenyl group, a C.sub.2 -C.sub.18 -alkynyl group, a C.sub.5 -C.sub.12 -cycloalkyl group, a C.sub.6 -C.sub.10 -bicycloalkyl group, a C.sub.5 -C.sub.8 -cycloalkenyl group, a C.sub.6 -C.sub.10 -aryl group, a C.sub.7 -C.sub.9 -aralkyl group or a C.sub.7 -C.sub.9 -aralkyl group, substituted by C.sub.1 -C.sub.4 -alkyl or phenyl, or R.sup.6 and R.sup.7 together are a radical of the formula II or III ##STR35## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined above, and X is a direct bond or methylene group or a 1,1-alkylidene group having 2 to 5 carbon atoms, R.sup.11, R.sup.12 and R.sup.13 are identical or different and are a C.sub.1 -C.sub.12 -alkylene group, a C.sub.5 -C.sub.7 -cycloalkylene group, a C.sub.8 -C.sub.10 -bicycloalkylene group, a C.sub.6 -C.sub.10 -arylene group, a C.sub.7 -C.sub.9 -aralkylene group or C.sub.7 -C.sub.9 -arylene group, substituted by C.sub.1 -C.sub.4 -alkyl or phenyl, R.sup.14, R.sup.15 and R.sup.16 are identical or different and are a trifunctional C.sub.3 -C.sub.18 -alkyl radical, C.sub.5 -C.sub.7 -cycloalkyl radical, C.sub.6 -C.sub.10 -aryl radical or C.sub.6 -C.sub.10 -aryl radical which is substituted by C.sub.1 -C.sub.4 -alkyl or phenyl,
• R.sup.17 and R.sup.18 are identical or different and are a C.sub.1 -C.sub.10 -alkyl group, a C.sub.5 -C.sub.7 -cycloalkyl group or a C.sub.6 -C.sub.10 -aryl group.