Poly 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylesters useful as thermal stabilizers for synthetic polymers

Compounds of formula (I) ##STR8## in which:

• A represents a linear or branched alkyl of 1-22 C atoms, optionally substituted with one or more groups chosen from alkoxy, alkylthio, hydroxyl optionally esterified with acrylic or alkoxy, alkylthio, hydroxyl optionally esterified with acrylic or methacrylic acid, halogen, aryl;
• phenyl or aryl of carbocyclic or heterocyclic type optionally substituted with one or more alkyl, alkoxy or halogen groups;
• alkenyl of 3-10 C atoms;
• CH.sub.3 COCH.sub.2 COO--R--;
• CH.sub.3 COCH.sub.2 COO--R.sup.1 ;
• CH.sub.3 --C(NH.sub.2).dbd.CH--COOR--;
• CH.sub.3 --C(NH.sub.2 .dbd.CHCOO--R.sup.1 --;
• in which the amino group can carry one or more substituents of alkyl, hydroxyalkyl or alkoxyalkyl type or a cyclic substituent of polyalkylene or oxapolyalkylene type, or methylene or a linear or branched alkenyl of 2-22 C atoms;
• B can assume the same meaning as A, or can represent a trivalent or polyvalent residue consisting of a linear or branched carbon atom chain optionally carrying substituents of alkoxy, thioalkoxy, aryl, carboxyl or hydroxyl type;
• m, n are whole numbers from 0 to 20, the sum of which is at least 2;
• k is 0 or 1;
• j is a whole number from 1 to 6;
• j (k+m+n) is a whole number equal or greater than 2;
• R and R.sup.1 each independently represent a bivalent hydrocarbon residue, a methylene or phenylene group, or a bivalent residue comprising at least one alkylene group of the type;
• --(--C.sub.p H.sub.2p --X--).sub.t --C.sub.p H.sub.2p
• in which p is a whole number from 2 to 18, t is a whole number from 0 to 10 and X is oxygen or sulphur, said alkylene group optionally carrying substitutions of alkoxy or thioalkoxy, aryl, carboxyl or hydroxyl type;
• or R and R.sup.1 represent a direct bond with B only if k is 0 and j is greater than 1:
• R.sub.2 represents hydrogen or a monovalent residue of linear or branched alkyl, alkoxycarbonyl.