More specifically, the present invention relates to synergistic stabilizing mixtures comprising two specific polyalkylpiperidines with a high molecular weight and their use as heat, oxidative degradation and light stabilizers of organic polymers.

The present invention also relates to the polymeric compositions stabilized with the above synergistic mixtures and the end-articles obtained from said compositions.

Stabilizing mixtures comprising two polyalkyl- piperidines are known in the art. For example, they are de- scribed in patents USA 4, 692, 486, USA 4, 863, 981 and USA 4, 957, 953, in International patent application WO 92/12201, in European patent applications EP 449, 685 and EP 632, 092, in English patent application GB 2, 267, 449 and in the publi- cation ("Research Disclosure") RD 34, 549 (January 1993).

European patent EP 728, 806 describes a stabilizing mix- ture comprising two specific polyalkylpiperidines one of which must be at least one compound having general formula (Ia) :

wherein R1 is a Cl-Clo alkyl group, a C5-C12 cycloalkyl group optionally substituted with C1-C4 alkyl groups, a phenyl op- tionally substituted with Cl-Clo alkyl groups ; R2 is a C3-ClO alkylene group ; R3 is a hydrogen atom, a C1-C8 alkyl group, 0', a-CH2CN group, a C3-C6 alkenyl group, a C7-Cg phenylalkyl group optionally substituted in the phenyl radical with C1-C4 alkyl groups, a C1-C8 acyl group ; and n1 is a number ranging from 1 to 50 extremes included.

A specific example of the compound having general for- mula (Ia) is the following : - poly-methylpropyl-3-oxy-[4-(2, 2, 6, 6-tetramethyl)-piper- idinyl] siloxane, known under the trade-name of UVASIL 299 of Great Lakes.

UVASIL 299 is a mixture of cyclic and linear products

corresponding to general formula (Ia) described above : the quantity of cyclic products and linear products varies ac- cording to the molecular weight to be obtained.

The Applicant has now found that the use of a siloxane corresponding to general formula (Ia) completely cyclic mixed with other specific polyalkylpiperidines having a high molecular weight, allows mixtures to be obtained with better synergistic values than those observed in the known art. The synergistic mixtures thus obtained consequently provide a greater heat, oxidative degradation and light stabilization of the organic polymers to which they are added.

The present invention therefore relates to stabilizing mixtures comprising at least one component (a) consisting of a compound having general formula (I) : wherein : Ri represents a Cl-Clo alkyl group ; a Cs-Cl2 cycloalkyl group, said cycloalkyl group optionally substituted

with C1-C4 alkyl groups ; a phenyl, said phenyl option- ally substituted with Cl-Clo alkyl groups ; -R2 represents a C3-Clo alkylene group ; R3 represents a hydrogen atom ; a C1-C8 alkyl group ; 0' ; a-CH2CN group ; a C3-C6 alkenyl group ; a C7-C9 phenylal- kyl group, said phenylalkyl group optionally substi- tuted in the phenyl radical with C1-C4 alkyl groups ; a Ci-Cg acyl group ; -n is a number ranging from 1 to 50 extremes included ; and at least one component selected from the following polyalkylpiperidines (b), (c), (d), (e), (f) and (g) wherein : (b) is at least one compound having general formula (II) : wherein : -R4, R6, R7 and R8, each independently represent a hydro- gen atom ; a Cl-C12 alkyl group ; a C5-C12 cycloalkyl group, said cycloalkyl group optionally substituted with Cl-C4 alkyl groups ; a phenyl group, said phenyl

group optionally substituted with-OH groups and/or with Cl-Cl0 alkyl groups ; a C7-Cg phenylalkyl group, said phenylalkyl group optionally substituted in the phenyl group with-OH groups and/or Cl-Cl0 alkyl groups ; a group having general formula (III) : Rs represents a C2-C18 alkylene group ; a C5-C7 cycloal- kylene group ; a Cl-C4 alkylene-di (C5-C7-cycloalkylene) group ; or the substituents R4, R5 and R6, together with the ni- trogen atoms to which they are bound, form a heterocy- clic ring with 5-10 atoms ; or, R7 and R8, together with the nitrogen atoms to which they are bound, form a heterocyclic ring with 5- 10 atoms ; Rg has the same meanings as R3 ; n2 is a number ranging from 2 to 50 extremes included, and at least one of the radicals R4, R6, R7 and RB repre- sents a group having general formula (III) ; (c) is at least one compound obtained by reacting a compound

obtained by the reaction of a polyamine having general for- mula (IVa) with cyanuric chloride, with a compound having general formula (IVb) : H2 N- (CH2)-NH- (CH2)-NH- (CH2)-NH2- na nb nc (IVa) wherein : -na, nb and nc are each independently a number ranging from 2 to 12 extremes included ; -Rlo represents a hydrogen atom ; a Cl-Cl2 alkyl group ; a C5-C12 cycloalkyl group ; a phenyl group ; a C7-Cg phen- ylalkyl group ; -Rll has the same meanings as R3 ; (d) is at least one compound having general formula (V) : wherein :

-R12 represents a hydrogen atom or a methyl ; Ri3 represents a direct bond or a Cl-Cl0 alkylene group ; n4 is a number ranging from 2 to 50 extremes included ; (e) is at least one compound having general formula (VIa) or (VIb) : wherein : -n5 and ns* are each independently a number ranging from 2 to 50 extremes included ; (f) is at least one compound having general formula (VII) :

wherein : Ri4 and R16, each independently represent a direct bond ; or an-N (X1)-CO-X2-CO-N (X3)-group wherein Xi and X3, each independently represent a hydrogen atom, a Cl-C8 alkyl group, a C5-Cl2 cycloalkyl group, a phenyl group, a C7-C9 phenylalkyl group, a group having general for- mula (III) ; X2 represents a direct bond, a Cl-C4 al- kylene group ; Ri5 has the same meanings as R3 ; Rie, R17, Rso and R21, each independently represent a hy- drogen atom ; a C1-C30 alkyl group ; a C5-Cl2 cycloalkyl group ; a phenyl group ; Rig represents a hydrogen atom ; a C1-C30 alkyl group ; a C5-C12 cycloalkyl group ; a C7-C9 phenylalkyl group ; a phenyl group ; a group having general formula (III) ; n6 is a number ranging from 1 to 50 extremes included ; (g) is at least one compound having general-formula (VIII) :

wherein : -R22, R23, R24, R25 and R26, each independently represent a direct bond ; a Cl-Cl0 alkylene group ; R27 has the same meanings as R3 ; n7 is a number from 1 to 50 extremes included.

Examples of alkyl groups having up to 30 carbon atoms are : methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1- methylpentyl, 1, 3-dimethylbutyl, n-hexyl, 1-methylhexyl, n- heptyl, isoheptyl, 1, 1, 3, 3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1, 1, 3-trimethylhexyl, 1, 1, 3, 3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methyl- undecyl, dodecyl, 1, 1, 3, 3, 5, 5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl, docosyl, triacontyl, etc. The substituents R3, Rg, Rll, R15, R17, R21 and R27 preferably represent a C1-C4 alkyl

group, in particular a methyl. The substituents R16 and R20 preferably represent a C1-C25 alkyl group, in particular a C15-C25 alkyl group such as, for example, hexadecyl or a C18- C22 alkyl group. The substituent Rl9 preferably represents a C1-C25 alkyl group, in particular octadecyl.

Examples of C5-Cl2 cycloalkyl groups are : cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, etc. C5-C8 cycloalkyl groups are preferred, in particular cyclohexyl.

Examples of C5-Cl2 cycloalkyl groups substituted with C1-C4 alkyl groups are : methylcyclohexyl, dimethylcyclohexyl, etc.

Examples of phenyl groups substituted with-OH groups and/or with Cl-Cl0 alkyl groups are : methylphenyl, dimethyl- phenyl, trimethylphenyl, t-butylphenyl, 3, 5-di-t-butyl-4- hydroxyphenyl, etc.

Examples of C7-C9 phenylalkyl groups are : benzyl, phen- ylethyl, etc.

Examples of C7-Cg phenylalkyl groups substituted in the phenyl group with-OH groups and/or alkyl groups having up to 10 carbon atoms, are : methylbenzyl, dimethylbenzyl, tri- methylbenzyl, t-butylbenzyl, 3, 5-di-t-butyl-4-hydroxyphenyl, etc.

Examples of C3-C6 alkenyl groups are : allyl, 2- methallyl, butenyl, pentenyl, hexenyl, etc. The allyl group is preferred.

Examples of Cl-C8 acyl groups are, preferably, C1-C8 al- kanoyl groups, C3-C8 alkenoyl groups, benzoyl. Examples of these groups are : formyl, acetyl, propionyl, butyryl, penta- noyl, hexanoyl, octanoyl, benzoyl, acryloyl, crotonyl, etc.

Examples of alkylene groups having up to 18 carbon at- oms are : methylene, ethylene, propylene, trimethylene, tet- ramethylene, pentamethylene, 2, 2-dimethyltrimethylene, hex- amethylene, trimethylhexamethylene, octamethylene, deca- methylene, etc. The substituent R5 preferably represents hexamethylene ; the substituent R13 preferably represents eth- ylene ; the substituents R22 and R24 preferably represent methylene ; the substituent R25 preferably represents 2, 2- dimethylethylene ; the substituent R26 preferably represents 1, 1-dimethylethylene.

An example of a C5-C7 cycloalkylene group is cyclohexy- lene.

An example of a C1-C4 alkylene-di (C5-C7-cycloalkylene) group is methylenedicyclohexylene.

Examples of heterocyclic rings with 5-10 atoms, when the substituents R4, R5 and R6 together with the nitrogen at- oms to which they are bound form a heterocyclic ring having 5-10 atoms, are :

Heterocyclic rings with 6 atoms are preferred.

Examples of heterocyclic rings with 5-10 atoms, when the substituents R7 and R8 together with the nitrogen atoms to which they are bound form a heterocyclic ring having 5-10 atoms, are : 1-pyrrolidyl, piperidine, morpholine, 1-pipe- razinyl, 4-methyl-1-piperazinyl, 1-hexahydroazepinyl, 5, 5, 7- trimethyl-1-homopiperazinyl, 4, 5, 5, 7-tetramethyl-1-homopi- perazinyl, etc. The morpholine group is preferred.

The substituents R16 and Rzo preferably represent a phenyl group.

The substituents X2 and R23 preferably represent a di- rect bond.

The substituents X1, X3, R3, Rg, Rll, Ris and R27 prefera- bly represent a hydrogen atom.

Preferably, nl is a number between 1 and 25 extremes included, in particular between 2 and 20 or 2 and 10 ex- tremes included ; n2 is a number between 2 and 25 extremes included ; na, nb and nc are a number between 2 and 4 extremes

included ; n4 is a number between 2 and 25 extremes included, in particular between 2 and 20 or 2 and 10 extremes in- cluded ; n5 and n5* are a number between 2 and 25, in particu- lar between 2 and 20 or 2 and 10 extremes included ; n6 is a number between 1 and 25 extremes included, in particular be- tween 1 and 20 or 1 and 10 extremes included ; n7 is a number between 1 and 25 extremes included, in particular between 1 and 20 or 1 and 10 extremes included.

Component (a) can be obtained as described, for exam- ple, in patents U. S. 4, 684, 726, U. S. 4, 946, 880 and U. S.

5, 051, 458.

The compounds described as components from (b) to (g) are generally known in the art and, in some cases, are com- mercially available ; or they can be prepared with known pro- cesses described, for example in patents U. S. 5, 051, 458, U. S. 4, 086, 204, U. S. 4, 331, 586, U. S. 4, 477, 615 and Chemical Abstract-CAS Nr. 136 504-96-6, U. S. 4, 233, 412, U. S.

4, 340, 534, U. S. 4, 857, 595, in patent application DD 262, 439 (Derwent 89-122 983/17), in Chemical Abstracts 111 : 58 964u, in patent application DE 4, 239, 437 (Derwent 94-177 274/22) and in the patent U. S. 4, 529, 760.

Component (c) can be prepared analogously to the known processes, for example, by the reaction of a polyamine hav- ing general formula (IVa) with cyanuric chloride in a molar ratio ranging from 1 : 2 to 1 : 4, in the presence of anhydrous

lithium carbonate, anhydrous sodium carbonate or anhydrous potassium carbonate, in an organic solvent, such as 1, 2- dichloroethane, toluene, xylene, benzene, dioxane or t-amyl alcohol, at a temperature ranging from-20°C to +10°C, pref- erably from-10°C to +10°C, in particular from 0°C to +10°C, for a time ranging from 2 to 8 hours, followed by the reac- tion of the product thus obtained with 2, 2, 6, 6-tetramethyl- 4-piperidylamine having general formula (IVb). The molar ra- tio between 2, 2, 6, 6-tetramethyl-4-piperidylamine and the polyamine having general formule (IVa) ranges, for example, from 4 : 1 to 8 : 1. The quantity of 2, 2, 6, 6-tetramethyl-4- piperidylamine can be added in one portion or more than one portion at intervals of a few hours.

The ratio polyamine having general formula (IVa) : cyanuric chloride : 2, 2, 6, 6-tetramethyl-4-piperidylamine hav- ing formula (IVb) preferably ranges from 1 : 3 : 5 to 1 : 3 : 6.

For example, component (c) can be prepared as described below.

Example : 23. 6 g (0. 128 moles) of cyanuric chloride, 7. 43 g (0. 0426 moles) of N, N'-bis (3-aminopropyl) ethylenediamine and 18 g (0. 13 moles) of anhydrous potassium carbonate, are re- acted at 5°C for 3 hours, under stirring, in 250 ml of 1, 2- dichloroethane. The mixture is heated to room temperature for the following 4 hours.

27. 2 g (0. 128 moles) of N- (2, 2, 6, 6-tetramethyl-4-

piperidyl) butylamine are added, and the resulting mixture is heated to 60°C for 2 hours. A further 18 g (0. 13 moles) of anhydrous potassium carbonate are added and the mixture is heated to 60°C for a further 6 hours. The solvent is removed by distillation under a light vacuum (200 mbars) and substi- tuted by xylene. 18. 2 g (0. 085 moles) of N- (2, 2, 6, 6- tetramethyl-4-piperidyl) butylamine and 5. 2 g (0. 13 moles) of ground sodium hydroxide are added, the mixture is left at reflux temperature for 2 hours and, after a further 12 hours, the water formed during the reaction is removed by azeotropic distillation. The mixture is filtered. The solu- tion is washed with water and dried on Na2SO4. The solvent is evaporated and the residue is dried at 120°C-130°C under vacuum (0. 1 mbar). The component (c) obtained is a transpar- ent resin.

Component (c) can generally be represented by one of the following compounds having general formula (IV-1), (IV- 2) or (IV-3) ; or, component (c) can also be a mixture of the above three compounds :

The preferred compound having general formula (IV-1) is : The preferred compound having general formula (IV-2) is :

The preferred compound having general formula (IV-3) is : In general formulae (IV-1), (IV-2) and (IV-3) and (IV- 1'), (IV-2') and (IV-3'), n3 is preferably a number ranging from 1 to 20 extremes included.

The following compounds are preferably used for the pur-

poses of the present invention : CHIMASSORB 9440, CYASORB UV 3346@ or DASTAB 1082@ as component (b), UVASORB HA 88@ as component (c), LOWILITE 62@ as component (d), HOSTAVIN N 30@ as component (e), UVINUL 5050 H@, LICHTSCHUTZSTOFF UV 31@ or LUCHEM B 18@ as component (f), MARK LA 63@ or MARK LA 68@ as component (g).

The compounds having general formula (VIa) and (VIb) can be used as a mixture or as such, as component (e) for the purposes of the present invention. The ratio (VIa) : VIb) ranges, for example, from 20 : 1 to 1 : 20, or from 1 : 10 to 10 : 1.

The meanings of the terminal groups which saturate the free valences in the compounds having general formula (II), (IV-1), (IV-2), (IV-3), (V), (VIa), (VIb), (VII) and (VIII), depend on the process used for their preparation. The termi- nal groups can also be modified after the preparation of the compounds.

When the compounds having general formula (II) are pre- pared by reacting a compound having general formula (IIa) : wherein X represents, for example, a halogen atom, prefera- bly chlorine, and R7 and R8 have the same meanings described above, with a compound having general formula (IIb) :

wherein R4, R5 and R6 have the same meanings defined above, the terminal group bound to the diamine radical is a hydro- gen atom or a compound having general formula (IIc) : and the terminal group bound to the triazine radical is a substituent X or a group having general formula (IId) : When X represents a halogen atom, it is advantageous to substitute it, for example, with an-OH group or an amine group at the end of the above reaction. Examples of amine groups which can be used for the purpose are : pyrrolidin-1- yl, morpholine,-NH2,-N [(Cl-C8)-alkyl] 2 and-NR (Ci-C9) alkyl

wherein R represents a hydrogen atom or a group having gen- eral formula (III).

In the compounds having general formula (IV-1), (IV-2) and (IV-3), the terminal group bound to the triazine radical is, for example, a chlorine atom or a group having general formula (IV-a') : wherein Rlo and Rll have the same meanings described above and the terminal group bound to the amine radical is, for example, a hydrogen atom or a group having general formula (IV-b') : wherein Rlo and Rll have the same meanings described above.

When the compounds having general formula (V) are pre- pared, for example, by reacting a compound having formula

(Va) : wherein R12 represents a hydrogen atom or a methyl group, with a diester of a dicarboxylic acid having general formula Y-OOC-R13-COO-Y wherein Y represents, for example, methyl, ethyl or propyl and R13 has the same meanings described above, the terminal group bound to the 2, 2, 6, 6-tetramethyl- 4-oxypiperidin-1-yl radical is a hydrogen atom or a group having general formula-CO-R13-COO-Y, and the terminal group bound to the diacyl radical is an-0-Y group or a group hav- ing general formula (Vb) : In the compounds having general formula (VIa), the ter- minal group bound to the nitrogen can be, for example, a hy- drogen atom and the terminal group bound to the 2- hydroxypropylene radical can be, for example, a group having formula (VIa') :

In the compounds having general formula (VIb), the ter- minal group bound to the dimethylene radical can be, for ex- ample, an-OH group and the terminal group bound to the oxy- gen can be, for example, a hydrogen atom. The terminal groups can also be polyether radicals.

In the compounds having general formula (VII), the ter- minal group bound to the 2, 5-dioxopyrrolidine ring is, for example, a hydrogen atom, and the terminal group bound to the-C (R20) (R21)-radical is, for example a group having gen- eral formula (VIIa) or (VIIb) :

wherein R14, R15, Rls and Rl9 have the same meanings described above.

In the compounds having general formula (VIII) the ter- minal group bound to the carbonyl radical is, for example, a group having general formula (VIIIa) : wherein R27 has the same meanings described above and the terminal group bound to the oxygen is, for example, a group having general formula (VIIIb) :

wherein R22, R23, R24 and R27 have the same meanings described above.

Preferred stabilizing mixtures for the purposes of the present invention are those wherein, in components (a) <BR> <BR> <BR> <BR> <BR> (g) Ri is a C1-C4 alkyl group, a C5-C8 cycloalkyl group, a phenyl group ; -R2 is a C3-C6 alkylene group ; -nl is a number from 1 to 25 ; -R3, Rg, R11 Ris and R27 are each independently a hydrogen atom or a methyl ; -R4, R6, R7 and Re are each independently a hydrogen atom ; a C1-C8 alkyl group ; a C5-C8 cycloalkyl group ; a phenyl group ; a C7-Cg phenylalkyl group ; a group having general formula (III) ; or, the substituents R7 and R8, together with the nitrogen atom to which they are bound, form a heterocyclic ring with 6 atoms ; - R5 represents a C2-Clo alkylene group ; -n2 is a number from 2 to 25 extremes included ; -na, nb and nc, are each independently a number from 2 to 4 extremes included ; -Rlo represents a C1-C4 alkyl group ; -R12 represents a hydrogen atom ; -R13 represents an ethylene group ; -n4 is a number from 2 to 25 extremes included ;

n5 and n5*, are each independently a number from 2 to 25 extremes included ; Ri4 and Ris represent a direct bond ; a-N (X1)-CO-X2-CO- N (X3))- group wherein X1 and X3 each independently rep- resent a hydrogen atom or a C1-C4 alkyl group and X2 represents a direct bond ; -R16 and R2o represent a C1-C25 alkyl group ; a phenyl group ; Ri7 and R21 represent a hydrogen atom ; a C1-C4 alkyl group ; -Rl9 represents a C1-C25 alkyl group ; a group having gen- eral formula (III) ; -n6 is a number from 1 to 25 extremes included ; -R22, R24, R25 and R26 represent a C1-C4 alkylene group ; -R23 represents a direct bond ; -n7 is a number from 1 to 25 extremes included.

Stabilizing mixtures even more preferable for the pur- poses of the present invention are those wherein component (a) is a compound (a') having formula (I-A') :

wherein R3 is a hydrogen atom or a methyl group and n is a number from 1 to 20, extremes included ; component (b) is at least one compound having formula (II-B- 1), (II-B-2) or (II-B-3) :

wherein n2 is a number from 2 to 20 extremes included ; component (c) is at least one compound obtained by reacting a product obtained from the reaction of a polyamine having formula (IVa-1) : H2N-(CH2)3-NH-(CH2)2-NH-(CH2)3-NH2 (IVa-1) with cyanuric chloride, with a compound having formula (IVb- 1) : component (d) is at least one compound having formula (V-D) :

wherein n4 is a number from 2 to 20 extremes included ; component (e) is at least one compound wherein n5 and n5* are each independently a number from 2 to 20 extremes included ; component (f) is at least one compound having formula (VII- F-1), (VII-F-2) or (VII-F-3) :

wherein n6 is a number from 1 to 20 extremes included ; component (g) is at least one compound having formula (VIII- G) : wherein R27 represents a hydrogen atom or a methyl and n7 is a number from 1 to 20 extremes included.

Examples of stabilizing mixtures which can be used for

the purposes of the present invention, which should not be considered as limiting its scope in any way, are : 1. stabilizing mixture comprising compounds (a) and (b) ; 2. stabilizing mixture comprising compounds (a) and (c) ; 3. stabilizing mixture comprising compounds (a) and (d) ; 4. stabilizing mixture comprising compounds (a) and (e) ; 5. stabilizing mixture comprising compounds (a) and (f) ; and 6. stabilizing mixture comprising compounds (a) and (g).

Particularly preferred are the following stabilizing mixtures : a) stabilizing mixture comprising at least one compound (a') and at least one compound having formula (II-B-1) ; b) stabilizing mixture comprising at least one compound (a') and at least one compound having formula (II-B-3) ; c) stabilizing mixture comprising at least one compound (a') and a product obtained from the reaction of a polyamine having formula (IVa-1) : H2 N- (CHz) 3 NH- (CH2) 2 NH- (CH2) 3-NH2 (IVa-1) with cyanuric chloride, with a compound having formula (IVb- 1) :

d) stabilizing mixture comprising at least one compound (a') and at least one compound having formula (V-D) ; e) stabilizing mixture comprising at least one compound (a') and at least one compound having formulae (VIa) and (VIb).

In the stabilizing mixtures described above, the two components are used in a weight ratio ranging from 0. 5 : 1 to 2 : 1, preferably in a weight ratio 1 : 1.

The above stabilizing mixtures can be used as heat, oxidative degradation and light stabilizers for organic polymers. Examples of organic polymers which can be stabi- lized are : 1. Polymers of mono-olefins and diolefins such as, for ex- ample, polypropylene, polyisobutylene, polybut-1-ene, poly-4- methylpent-1-ene, polyisoprene or polybutadiene ; as well as polymers of cyclo-olefins such as, for example, cyclopentene or norbornene ; polyethylene (which can be optionally cross- linked) such as, for example, high density polyethylene (HDPE), high density and high molecular weight polyethylene

(HDPE-HMW), high density and ultrahigh molecular weight poly- ethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE).

Polyolefins such as, for example the mono-olefins men- tioned in the above paragraph, preferably polyethylene and polypropylene, can be prepared with various methods known in literature, preferably using the following methods : (a) radical polymerization (generally carried out at a high pressure and high temperature) ; (b) catalytic polymerization using a catalyst which normally contains one or more metals of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals generally have one or more ligands such as, for example, oxides, hal- ides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls which can be 7t-or a-coordinated.

These metal complexes can be in free form or supported on substrates such as, for example, activated magnesium chloride, titanium (III) chloride, alumina or silicon ox- ide. These catalysts can be soluble or insoluble in the reaction medium. The catalysts can be used alone or in the presence of other activators such as, for example, metal alkyls, metal hydrides, halides of metal alkyls, oxides of metal alkyls or metal alkyloxanes, these met- als being elements belonging to groups Ia, IIa and/or

IIIa of the Periodic Table. The activators can be conve- niently modified with other ester, ether, amine or si- lyl-ether groups. These catalytic systems are usually called Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (Du-Pont), metallocene or"single site catalyst" (SSC).

2. Mixtures of the polymers described under point (1) such as, for example, mixtures of polypropylene with polyisobutyl- ene ; mixtures of polypropylene with polyethylene (for exam- ple, PP/HDPE, PP/LDPE) ; mixtures of different types of poly- ethylene (for example, LDPE/HDPE).

3. Copolymers of mono-olefins and diolefins with each other or with other vinyl monomers such as, for example, ethyl- ene/propylene copolymers, linear low density polyethylene (LLDPE) and its mixtures with low density polyethylene (LDPE), propylene/but-l-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copolymers, ethylene/methylpentene copolymers, ethylene/hep- tene copolymers, ethylene/octene copolymers, propyle- ne/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacryl- ate copolymers, ethylene/vinyl acetate copolymers and their copolymers with carbon monoxide or ethylene/acrylic acid co- polymers and their salts (ionomers) as well as terpolymers of ethylene with polypropylene and a diene such as, for example,

hexadiene, dicyclopentadiene or ethylidene-norbornene ; and mixtures of these copolymers with each other or with the polymers cited in paragraph (1) such as, for example, poly- propylene/ethylene/propylene copolymers, LDPE/ethylene/vinyl- acetate (EVA) copolymers, LDPE/ethylene/acrylic acid (EAA) copolymers, LLDPE/EVA, LLDPE/EAA, and alternating or random polyalkylene/carbon monoxide copolymers and their mixtures with other polymers such as, for example, polyamides.

4. Hydrocarbon resins (for example, C5-C9) comprising their hydrogenated modifications (for example, adhesive agents) and mixtures with polyalkylene and starch.

5. Polystyrene, poly (p-methylstyrene), poly (a-methylstyre- ne).

6. Copolymers of styrene or a-methylstyrene with dienes or acrylic derivatives such as, for example, styrene/butadiene, styrene/acrylonitrile, styrene/alkyl methacrylate, styrene/ butadiene/alkyl acrylate, styrene/butadiene/alkyl methacryla- te, styrene/maleic anhydride, styrene/acrylonitrile/methyl acrylate ; mixtures, having a high impact strength, between copolymers of styrene and another polymer such as, for exam- ple, a polyacrylate, a polymer of a diene or an ethy- lene/propylene/diene terpolymer, block copolymers of styrene such as, for example, styrene/butadiene/styrene, styrene/iso- prene/styrene, styrene/ethylene/butylene/styrene or styrene/ ethylene/propylene/styrene.

7. Grafted copolymers of styrene or of a-methylstyrene such as, for example, styrene on polybutadiene, styrene on polybu- tadiene or polybutadiene-acrylonitrile copolymers ; styrene and acrylonitrile (or methacrylonitrile) on polybutadiene ; styrene, acrylonitrile and methylmethacrylate on polybuta- diene ; styrene and maleic anhydride on polybutadiene ; sty- rene, acrylonitrile and maleic anhydride or maleimide on polybutadiene ; styrene and maleimide on polybutadiene ; sty- rene and alkylacrylates or methacrylates on polybutadiene ; styrene and acrylonitrile on ethylene/propylene/diene ter- polymers, styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on ac- rylate/butadiene copolymers, as well as mixtures of the co- polymers listed above with the copolymers cited under point (6) such as, for example, mixtures of known copolymers such as ABS, MBS, ASA or AES.

8. Polymers containing halogens such as, for example, poly- chloroprene, chlorinated rubbers, chlorinated or brominated isobutylene-isoprene copolymers ("halobutyl rubber"), chlo- rinated or chlorosulfonated polyethylene, ethylene and chlo- rinated ethylene copolymers, homopolymers and copolymers of epichlorohydrin, in particular polymers of vinyl compounds containing halogens such as, for example, polyvinyl chloride, polyvinylidenechloride, polyvinyl fluoride or polyvinylidene- fluoride ; and also their copolymers such as, for example, vi-

nyl chloride/vinylidenechloride, vinyl chloride/vinyl acetate or vinylidenechloride/vinyl acetate.

9. Polymers deriving from a, p-unsaturated acids and their derivatives such as, for example, polyacrylates and poly- methacrylates, polymethyl methacrylates, polyacrylamides and polyacrylonitriles, modified with butyl acrylate.

10. Copolymers of monomers according to point (9) with each other or with other unsaturated monomers such as, for exam- ple, acrylonitrile/butadiene copolymers, acrylonitrile/alkyl acrylate copolymers, acrylonitrile/alkoxyalkyl acrylate co- polymers or acrylonitrile/vinyl halide copolymers or acrylo- nitrile/alkyl methacrylate/butadiene terpolymers.

11. Polymers deriving from unsaturated alcohols and amines, or their acyl or acetal derivatives such as, for example, polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyrral, polyallyl phthalate or polyallyl melamine ; and also their co- polymers with the olefins listed under point (1).

12. Homopolymers and copolymers of open-chain ethers or cy- clic ethers such as, for example, polyalkylene glycols, poly- ethylene oxide, polypropylene oxide, or copolymers of the compounds described above with bis-glycidyl ethers.

13. Polyacetals such as, for example, polyoxymethylene and those polyoxymethylenes containing ethylene oxide as comono- mer ; polyacetals modified with thermoplastic polyurethanes,

acrylates or MBS.

14. Polyphenylene oxides and sulfides and mixtures of poly- phenylene oxides with styrene polymers or polyamide.

15. Polyurethanes deriving from hydroxyl-terminated poly- ethers, polyesters or polybutadienes on the one hand and ali- phatic or aromatic polyisocyanates on the other, as well as the precursors of the above compounds.

16. Polyamides and copolyamides deriving from diamines and dicarboxylic acids and/or aminocarboxylic acids or from the corresponding lactams such as, for example, polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides obtained starting from m-xylene diamine and adipic acid ; polyamides prepared from hexamethylenediamine and isophthalic and/or terephthalic acid and with or without an elastomer as modi- fier, for example, poly-2, 4, 4-trimethylhexamethylene tereph- thalamide or poly-m-phenylene isophthalamide ; and also block copolymers of the above polyamides with polyolefins, olefinic copolymers, ionomers or elastomers chemically bound or grafted ; or with polyethers such as, for example, polyethyl- ene glycol, polypropylene glycol or polytetramethylene gly- col ; as well as polyamides or copolyamides modified with EPDM or ABS ; and polyamides condensed during processing ("RIM polyamide system").

17. Polyureas, polyimides, polyamide-imides and polybenzo-

imidazoles.

18. Polyesters deriving from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or from the corresponding lactones such as, for example, polyethylene terephthalate, polybutylene terephthalate, poly-1, 4-dimethylolcyclohexane terephthalate and polyhydroxybenzoates, as well as block co- polyether esters deriving from polyethers with hydroxyl- terminated groups ; and also polyesters modified with polycar- bonates or MBS.

19. Polycarbonates and polyester carbonates.

20. Polysulfones, polyethersulfones and polyetherketones.

21. Cross-linked polymers deriving from aldehydes on the one hand and from phenols, urea and melamines on the other, such as, for example, phenol/formaldehyde resins, urea/formal- dehyde resins and melamine/formaldehyde resins.

22. Drying or non-drying alkyd resins.

23. Resins based on unsaturated polyesters deriving from co- polyesters of dicarboxyl acids saturated and unsaturated with polyhydric alcohols and vinyl compounds as cross-linking agents, and also the above resins containing halogens and having a good flame-resistance.

24. Cross-linkable acrylic resins deriving from substituted acrylates such as, for example, epoxy acrylates, urethane ac- rylates or polyester acrylates.

25. Alkyd resins, resins based on polyesters or acrylated

resins cross-linked with melamine resins, resins based on urea, resins based on isocyanates, resins based on iso- cyanurates, resins based on polyisocyanates or epoxy resins.

26. Cross-linked epoxy resins deriving from aliphatic, cy- cloaliphatic, heterocyclic or aromatic glycidyl compounds such as, for example, products of diglycidyl ethers of bisphenol A and bisphenol F, which are cross-linked with the usual hardening agents such as, for example, anhydrides or amines, in the presence of or without accelerating agents.

27. Natural polymers such as, for example, cellulose, rub- ber, gelatine, and their derivatives chemically modified to give homologous polymers such as, for example, cellulose ace- tates, propionates and butyrates, or cellulose ethers such as, for example, methyl-cellulose ; as well as hydrocarbon resins ("rosins") and their derivatives.

28. Mixtures of the above polymers ("polyblends") such as, for example, PP/EPDM, polyamides/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylates, POM/MBS, PPO/HIPS, PPO/PA 6. 6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS, PBT/PET/PC.

29. Natural or synthetic organic materials which are pure monomeric compounds or mixtures of said compounds, such as, for example, mineral oils, animal or vegetable oils, fats or waxes, oils, fats or waxes based on synthetic esters (for

example, phthalates, adipates, phosphates, trimellitates), as well as mixtures of synthetic esters with mineral oils in any weight ratio, in particular those used in spinning com- positions, as well as aqueous emulsions of said organic ma- terials.

30. Aqueous emulsions of natural or synthetic rubbers such as, for example, natural latex or latexes based on carboxy- lated styrene-butadiene copolymers.

The present invention also relates to polymeric compo- sitions containing an organic polymer and an effective quan- tity of the above stabilizing mixtures.

The stabilizing mixtures of the present invention are particularly useful in the stabilization of synthetic or- ganic polymers selected from those listed above. They are preferably used in the stabilization of polyolefins, more preferably in the stabilization of polyethylene, polypropyl- ene and their copolymers, of mechanical mixtures consisting of polyethylene and polypropylene, polypropylene with sty- rene/butadiene rubbers (SBR), or with ethylene/propylene rubbers or with ethylene/propylene/diene rubbers.

The components of the stabilizing mixtures of the pres- ent invention can be added to the polymers to be stabilized individually or mixed with each other. The components can be used, each independently, in a quantity ranging from 0. 005% to 3. 5%, on the condition that the total quantity of compo-

nent (a) and component (b), (c), (d), (e), (f) or (g) ranges from 0. 01% to 5% with respect to the total weight of the polymer to be stabilized.

The total quantity of component (a) and component (b), (c), (d), (e), (f) or (g) ranges from 0. 05% to 3%, specifi- cally ranges from 0. 05% to 2%, more specifically from 0. 1% to 1%, with respect to the total weight of the polymer to be stabilized.

The weight ratio between component (a) and component (b), (c), (d), (e), (f) or (g) preferably ranges from 20 : 1 to 1 : 20, in particular from 5 : 1 to 1 : 5, more specifically from 2 : 1 to 1 : 2.

The stabilizing mixtures of the present invention or the single components described above can be incorporated into the organic polymer to be stabilized using known tech- niques such as, for example, before or during processing ; or, these mixtures or components dissolved or dispersed in solvents, can be applied to the polymer to be stabilized, if necessary, after evaporation of the solvents in which they are dissolved or dispersed. The single components of the above mixtures can be added to the organic polymer to be stabilized in the form of powders, granules or masterbatch which contains said components in a concentration ranging from 2. 5% to 80%.

If necessary, the components of the above stabilizing

mixtures can be melted and mixed with each other before in- corporation into the organic polymer.

The stabilizing mixtures of the present invention or their single components can also be added during the polym- erization process or before cross-linking.

The polymeric compositions thus stabilized can be transformed into a wide variety of end-articles such as, for example, films, fibres, tapes, moulding compositions, lig- ands for paints, adhesives, putties.

The present invention therefore also relates to the use of the above polymeric compositions for the production of end-articles.

The stabilizing mixtures of the present invention can be combined with other conventional additives or their mix- tures. These additives are added in a quantity ranging from about 0. 1% to about 5% by weight with respect to the weight of the polymeric compositions to be stabilized, preferably from about 0. 5% to about 3% by weight. Some of the additives used are listed below as an example.

1. Antioxidants 1. 1 Alkylated monophenols such as, for example : 2, 6-di-t- butyl-4-methylphenol ; 2-t-butyl-4, 6-dimethylphenol ; 2, 6-di- t-butyl-4-ethylphenol ; 2, 6-di-t-butyl-4-n-butylphenol ; 2, 6- di-t-butyl-4-isobutylphenol ; 2, 6-dicyclopentyl-4-methyl- phenol ; 2- (a-methylcyclohexyl)-4, 6-dimethylphenol ; 2, 6-dio-

ctadecyl-4-methylphenol ; 2, 4, 6-tricyclohexylphenol ; 2, 6-di- t-butyl-4-methoxymethylphenol ; nonylphenols with a linear or branched alkyl chain such as, for example, 2, 6-di-nonyl-4- methylphenol ; 2, 4-dimethyl-6- (l'-methylundec-l'-yl) phenol ; 2, 4-dimethyl-6- (1'-methylheptadec-1'-yl) phenol ; 2, 4-dimethyl -6- (1'-methyltridec-1'-yl) phenol ; and their mixtures.

1. 2 Alkylthiomethylphenols such as, for example : 2, 4-dioc- tylthiomethyl-6-t-butylphenol ; 2, 4-dioctylthiomethyl-6-me- thylphenol ; 2, 4-dioctylthiomethyl-6-ethylphenol ; 2, 6-dido- decylthiomethyl-4-nonylphenol.

1. 3 Hydroquinones and alkylated hydroquinones such as, for example : 2, 6-di-t-butyl-4-methoxyphenol ; 2, 5-di-t-butyl- hydroquinone ; 2, 5-di-t-amylhydroquinone ; 2, 6-di-phenyl-4- octadecyloxyphenol ; 2, 6-di-t-butylhydroquinone ; 2, 5-di-t- butyl-4-hydroxyanisol ; 3, 5-di-t-butyl-4-hydroxyanisol ; 3, 5- di-t-butyl-4-hydroxyphenyl stearate ; bis (3, 5-di-t-butyl-4- hydroxyphenyl) adipate.

1. 4 Tocopherols such as, for example:a-tocopherol,P- tocopherol, y-tocopherol, 8-tocopherol and their mixtures (Vitamin E).

1. 5 Hydroxylated thiodiphenyl ethers such as, for example 2, 2'-thiobis-(6-t-butyl-4-methylphenol) ; 2, 2'-thiobis- (4- octylphenol) ; 4, 4'-thiobis- (6-t-butyl-3-methylphenol) ; 4, 4'-thiobis- (6-t-butyl-2-methylphenol) ; 4, 4'-thiobis (3, 6- di-s-amylphenol ;

4, 4'-bis- (2, 6-dimethyl-4-hydroxy-phenyl) disulfide.

1. 6 Alkylidene-bisphenols such as, for example : 2, 2'-methyl enebis- (6-t-butyl-4-methylphenol) ; 2, 2'-methylenebis- (6-t- butyl-4-ethylphenol) ; 2, 2'-methylenebis [4-methyl-6- (a-meth- ylcyclohexyl) phenol] ; 2, 2'-methylenebis (4-methyl-6-cyclo- hexylphenol) ; 2, 2'-methylenebis (6-nonyl-4-methyl-phenol) ; 2, 2'-methylenebis (4, 6-di-t-butylphenol) ; 2, 2'-ethylidene- bis (4, 6-di-t-butylphenol) ; 2, 2'-ethylidenebis (6-t-butyl-4- isobutylphenol) ; 2, 2'-methylenebis [6- (a-methylbenzyl)-4- nonylphenol] ; 2, 2'-methylenebis [6-(a, a-dimethylbenzyl)-4- nonylphenol] ; 4, 4'-methylenebis (2, 6-di-t-butylphenol) ; 4, 4'- methylenebis (6-t-butyl-2-methylphenol) ; 1, 1-bis (5-t-butyl-4- hydroxy-2-methylphenyl) butane ; 2, 6-bis (3-t-butyl-5-methyl-2- hydroxybenzyl)-4-methylphenol ; 1, 1, 3-tris- (5-t-butyl-4-hydr- oxy-2-methylphenyl) butane ; 1, 1-bis (5-t-butyl-4-hydroxy-2- methylphenyl)-3-n-dodecyl-mercaptobutane ; ethyleneglycol bis [3, 3-bis- (3'-t-butyl-4'-hydroxyphenyl)-butyrate] ; bis (3- t-butyl-4-hydroxy-5-methylphenyl) dicyclopentadiene ; bis [2- (3'-t-butyl-2'-hydroxy-5'-methylbenzyl)-6-t-butyl-4-methyl- phenyl] terephthalate ; 1, 1-bis (3, 5-dimethyl-2-hydroxy-phen- yl) butane ; 2, 2-bis- (3, 5-di-t-butyl-4-hydroxyphenyl)-propane ; 2, 2-bis (5-t-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmer- captobutane ; 1, 1, 5, 5-tetra (5-t-butyl-4-hydroxy-2-methylphe- nyl) pentane.

1. 7 Benzyl compounds containing 0, N or S such as, for

example : 3, 5, 3', 5'-tetra-t-butyl-4, 4'-dihydroxydibenzyl- ether ; octadecyl-4-hydroxy-3, 5-dimethylbenzylmercapto- acetate ; tridecyl-4-hydroxy-3, 5-di-t-butyl-benzyl- mercaptoacetate ; tris (3, 5-di-t-butyl-4-hydroxybenzyl) amine ; bis (4-t-butyl-3-hydroxy-2, 6-dimethylbenzyl) dithiotereph- thalate ; bis (3, 5-di-t-butyl-4-hydroxybenzyl) sulfide ; iso- octyl-3, 5-di-t-butyl-4-hydroxybenzylmercaptoacetate.

1. 8 Hydroxybenzylated malonates such as, for example : dioctadecyl-2, 2-bis (3, 5-di-t-butyl-2-hydroxybenzyl) malon- ate ; dioctadecyl-2- (3-t-butyl-4-hydroxy-5-methylbenzyl)- malonate ; didodecylmercaptoethyl-2, 2-bis (3, 5-di-t-butyl-4- hydroxybenzyl) malonate ; bis [4- (1, 1, 3, 3-tetramethyl- butyl) phenyl]-2, 2-bis (3, 5-di-t-butyl-4-hydroxybenzyl)- malonate.

1. 9 Aromatic hydroxybenzyl compounds such as, for example : 1, 3, 5-tris (3, 5-di-t-butyl-4-hydroxybenzyl)-2, 4, 6-trimethyl- benzene ; 1, 4-bis- (3, 5-di-t-butylhydroxybenzyl)-2, 3, 5, 6-te- tramethylbenzene ; 2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) phenol.

1. 10 Triazine compounds such as, for example : 2, 4-bis (octyl- mercapto)-6- (3, 5-di-t-butyl-4-hydroxyaniline)-1, 3, 5-tri- azine ; 2-octylmercapto-4, 6-bis (3, 5-di-t-butyl-4-hydroxy- aniline)-1, 3, 5-triazine ; 2-octylmercapto-4, 6-bis (3, 5-di-t- butyl-4-hydroxyphenoxy)-1, 3, 5-triazine ; 2, 4, 6-tris- (3, 5-di- t-butyl-4-hydroxyphenoxy)-1, 2, 3-triazine ; 1, 3, 5-tris (3, 5-di-

t-butyl-4-hydroxybenzyl) isocyanurate ; 1, 3, 5-tris (4-t-butyl- 3-hydroxy-2, 6-dimethylbenzyl) isocyanurate ; 2, 4, 6-tris- (3, 5- di-t-butyl-4-hydroxyphenylethyl)-1, 3, 5-triazine ; 1, 3, 5- tris (3, 5-di-t-butyl-4-hydroxyphenylpropionyl) hexahydro- 1, 3, 5-triazine ; 1, 3, 5-tris (3, 5-dicyclohexyl-4-hydroxyben- zyl) isocyanurate.

1. 11 Benzylphosphonates such as, for example : dimethyl-2, 5- di-t-butyl-4-hydroxybenzylphosphonate ; diethyl-3, 5-di-t- butyl-4-hydroxybenzylphosphonate ; dioctadecyl-3, 5-di-t- butyl-4-hydroxybenzylphosphonate ; dioctadecyl-5-t-butyl-4- hydroxy-3-methylbenzylphosphonate ; calcium salts of mono- ethyl ester of 3, 5-di-t-butyl-4-hydroxybenzylphosphonic acid.

1. 12 Acylaminophenols such as, for example : 4-hydroxylaura- nilide ; 4-hydroxystearanilide ; octyl-N- (3, 5-di-t-butyl-4- hydroxyphenyl) carbamate.

1. 13 Esters of P- (3, 5-di-t-butyl-4-hydroxyphenyl) propionic acid with monohydric or polyhydric alcohols such as, for ex- ample : methanol, ethanol, n-octanol, i-octanol, octadecanol, 1, 6-hexandiol, 1, 9-nonandiol, ethylene glycol, 1, 2-propa- nediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxye- thyl) isocyanurate, N, N'-bis (hydroxyethyl) oxamide, 3-thio- undecanol, 3-thiopentadecanol, trimethylhexandiol, trimethy-

lolpropane, 4-hydroxymethyl-1-phospho-2, 6, 7-trioxabicyclo- [2. 2. 2] octane.

1. 14 Esters of ß-(5-t-butyl-4-hydroxy-3-methylphenyl) pro- pionic acid with monohydric or polyhydric alcohols such as, for example : methanol, ethanol, n-octanol, i-octanol, oc- tadecanol, 1, 6-hexandiol, 1, 9-nonandiol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) oxamide, 3-thioundecanol, 3-thiopentadecanol, trimethylhexandiol, trimethylolpropane, 4-hydroxymethyl-1-phospho-2, 6, 7-trioxa- bicyclo [2. 2. 2] octane.

1. 15 Esters of P- (3, 5-dicyclohexyl-4-hydroxyphenyl) pro- pionic acid with monohydric or polyhydric alcohols such as, for example : methanol, ethanol, n-octanol, i-octanol, oc- tadecanol, 1, 6-hexandiol, 1, 9-nonandiol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl)- oxamide, 3-thioundecanol, 3-thiopentadecanol, trimethylhex- andiol, trimethylolpropane, 4-hydroxymethyl-1-phospho-2, 6, 7- trioxabicyclo [2. 2. 2] octane.

1. 16 Esters of (3, 5-di-t-butyl-4-hydroxyphenyl) acetic acid with monohydric or polyhydric alcohols such as, for example :

methanol, ethanol, n-octanol, i-octanol, octadecanol, 1, 6- hexandiol, 1, 9-nonandiol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) iso- cyanurate, N, N'-bis (hydroxyethyl) oxamide, 3-thioundecanol, 3-thiopentadecanol, trimethylhexandiol, trimethylolpropane, 4-hydroxymethyl-1-phospho-2, 6, 7-trioxabicyclo [2. 2. 2] octane.

1. 17 Amides of ß-(3, 5-di-t-butyl-4-hydroxyphenyl) propionic acid such as, for example : N, N'-bis (3, 5-di-t-butyl-4-hydro- xyphenylpropionyl) hexamethylenediamine ; N, N'-bis (3, 5-di-t- butyl-4-hydroxyphenylpropionyl) trimethylenediamine ; N, N'-bis (3, 5-di-t-butyl-4-hydroxyphenylpropionyl) hydrazine.

1. 18 Ascorbic acid (vitamin C).

1. 19 Amine antioxidants such as, for example, N, N'-di- isopropyl-p-phenylenediamine ; N, N'-di-s-butyl-p-phenylene- diamine ; N, N'-bis (1, 4-dimethylpentyl)-p-phenylenediamine ; N, N'-bis (1-ethyl-3-methylpentyl)-p-phenylenediamine ; N, N'- bis (1-methylheptyl)-p-phenylenediamine ; N, N'-dicyclohexyl- p-phenylenediamine ; N, N'-diphenyl-p-phenylenediamine ; N, N'- bis (2-naphthyl)-p-phenylenediamine ; N-isopropyl-N'-phenyl-p- phenylenediamine ; N- (1, 3-dimethylbutyl)-N'-phenyl-p-phenyl- enediamine ; N- (l-methylheptyl)-N'-phenyl-p-phenylenediami- ne ; N-cyclohexyl-N'-phenyl-p-phenylenediamine ; 4- (p-tolu- enesulfamoyl) diphenyleneamine ; N, N'-dimethyl-N, N'-di-s- butyl-p-phenylenediamine ; diphenylamine ; N-allyldiphenyl-

amine ; 4-isopropoxydiphenylamine ; N-phenyl-1-naphthylamine ; N- (4-t-octylphenyl) l-naphthylamine ; N-phenyl-2-naphthyl- amine ; diphenylamine octylate such as, for example, p, p'- di-t-octyldiphenylamine ; 4-n-butylaminophenol ; 4-butirylami- nophenol ; 4-nonanoylaminophenol ; 4-dodecanoylaminophenol ; 4- octadecanoylaminophenol ; bis (4-methoxyphenyl) amine ; 2, 6-di- t-butyl-4-dimethylaminomethylphenol ; 2, 4'-diaminodiphenyl- methane ; 4, 4'-diamino-diphenylmethane ; N, N, N', N'-tetra- methyl-4, 4'-diaminodiphenylmethane ; 1, 2-bis [ (2-methyl- phenyl) amino] ethane ; 1, 2-bis (phenylamino) propane ; (o-to- lyl) biguanide ; bis [4- (1', 3'-dimethylbutyl) phenyl] amine ; N- phenyl-1-naphthylamine t-octylate ; mixture of mono-and di- alkylated t-butyl/t-octyldiphenylamines ; mixture of mono- and dialkylated nonyldiphenylamines ; mixture of mono-and dialkylated dodecyldiphenylamines ; mixture of mono-and di- alkylated isopropyl/isohexyldiphenylamines ; mixture of mo- no-and dialkylated t-butyldiphenylamines ; 2, 3-dihydro-3, 3- dimethyl-4H-1, 4-benzothiazine ; phenothiazine ; mixture of mo- no-and dialkylated t-butyl/t-octylphenothiazines ; mixture of mono-and dialkylated t-octylphenothiazines ; N-allyl- phenothiazine ; N, N, N', N'-tetraphenyl-1, 4-diaminobut-2-ene ; N, N-bis (2, 2, 6, 6-tetramethyl-piperid-4-yl) hexamethylene- diamine ; bis (2, 2, 6, 6-tetramethylpiperid-4-yl) sebacate ; 2, 2, 6, 6-tetramethylpiperidin-4-one ; 2, 2, 6, 6-tetramethylpiperid- in-4-ol.

2. UV ray and light stabilizers.

2. 1 Derivatives of 2-(2'-hydroxyphenyl) benzotriazoles such as, for example : 2- (2'-hydroxy-5'-methylphenyl) benzotri- azole ; 2- (3', 5'-di-t-butyl-2'-hydroxyphenyl) benzotriazole ; 2- (5'-t-butyl-2'-hydroxyphenyl) benzotriazole ; 2- [2'-hydroxy- -5'- (1, 1, 3, 3-tetramethylbutyl) phenyl] benzotriazole ; 2-(3',- 5'-di-t-butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole ; 2- (3'-t-butyl-2'-hydroxy-5'-methylphenyl)-5-chlorobenzotri- azole 2- (3'-sec-butyl-5'-t-butyl-2'-hydroxyphenyl) benzo- triazole ; 2- (2'-hydroxy-4'-octyloxyphenyl) benzotriazole ; 2- (3', 5'-di-t-amyl-2'-hydroxyphenyl) benzotriazole ; 2- [3', 5'- bis (a, a-di-methylbenzyl)-2'-hydroxyphenyl] benzotriazole ; mixtures of 2- [3'-t-butyl-2'-hydroxy-5'- (2-octyloxycarbon- ylethyl) phenyl]-5-chlorobenzotriazole, 2- [3'-t-butyl-5'- (2- (2-ethylhexyloxy) carbonylethyl)-2'-hydroxyphenyl]-5-chloro- benzotriazole, 2- [3'-t-butyl-2'-hydroxy-5'- (2-methoxycarb- onylethyl) phenyl]-5-chlorobenzotriazole, 2- [3'-t-butyl-2'- hydroxy-5'- (2-methoxycarbonylethyl) phenyl] benzotriazole, 2- [3'-t-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl]- benzotriazole, 2- [3'-t-butyl-5'- (2- (2-ethylhexyloxy) carbon- ylethyl)-2'-hydroxyphenyl] benzotriazole, 2- (3'-dodecyl-2'- hydroxy-5'-methylphenyl) benzotriazole and 2- [3'-t-butyl-2'- hydroxy-5'-(2-iso-octyloxycarbonylethyl)phenyl]benzotri- azole, 2, 2'-methylene-bis [4- (1, 1, 3, 3-tetramethylbutyl)-6- benzotriazol-2-yl-phenol] ; transesterification product of 2-

[3'-t-butyl-5'- (2-methoxycarbonylethyl)-2'-hydroxyphenyl]- 2H-benzotriazole with polyethylene glycol 300 ; [R-CH2CH2- COO (CH2) 3-l2-wherein R 3'-t-butyl-4-hydroxy-5'-2H- benzotriazol-2-yl-phenyl.

2. 2 Derivatives of 2-hydroxybenzophenones such as, for ex- ample : 4-hydroxy- ; 4-methoxy- ; 4-octyloxy- ; 4-decyloxy- ; 4- dodecyloxy- ; 4-benzyloxy- ; 4, 2', 4'-trihydroxy- ; 2'-hydroxy- 4, 4'-dimethoxy.

2. 3 Esters of benzoic acids, optionally substituted, such as, for example : phenyl salicylate, 4-t-butylphenyl salicy- late, octylphenyl salicylate, benzoyl resorcinol, bis (4-t- butylbenzoyl) resorcinol, dibenzoyl resorcinol, 2, 4-di-t- butylphenyl-3, 5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3, 5- di-t-butyl-4-hydroxybenzoate, octadecyl-3, 5-di-t-butyl-4- hydroxybenzoate, 2-methyl-4, 6-di-t-butylphenyl-3, 5-di-t-but- yl-4-hydroxybenzoate.

2. 4 Acrylates such as, for example, ethyl or isoctyl a- cyan-0, p-diphenylacrylate ; methyl a-carbomethoxycinnamate, methyl or butyl a-cyano-ß-methyl-p-methoxycinnamate, methyl a-carbomethoxy-p-methoxycinnamate, N-(ß-carbomethoxy-ß-cy- anovinyl)-2-methylindoline.

2. 5 Nickel compounds such as, for example, complexes of 2, 2'-thio-bis- [4- (1, 1, 3, 3-tetramethylbutyl) phenol], for ex- ample 1 : 1 or 1 : 2 complexes, with or without additional lig- ands such as n-butylamine, triethanolamine or N-cyclohexyl-

diethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters of 4-hydroxy-3, 5-di-t-butyl-benzyl-phos- phonic acid, such as methyl or ethyl esters, nickel com- plexes with ketoximes such as 2-hydroxy-4-methylphenyl unde- cyl ketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hyd- roxypyrazol with or without additional ligands.

2. 6 Sterically hindered amines such as, for example : bis- (2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate ; bis (2, 2, 6, 6-tet- ramethyl-4-piperidyl) succinate ; bis (1, 2, 2, 6, 6-pentamethyl- -4-piperidyl) sebacate ; bis (1-octyloxy-2, 2, 6, 6-tetramethyl-4- piperidyl) sebacate ; bis (1, 2, 2, 6, 6-pentamethyl-4-piperid- yl) n-butyl-3, 5-di-t-butyl-4-hydroxybenzylmalonate ; condensa- tion product between N, N'-bis (2, 2, 6, 6-tetramethyl-4-piper- idyl) hexamethylendiamine and 4-t-octylamino-2, 6-di-chloro- 1, 3, 5-triazine ; tris (2, 2, 6, 6-tetramethyl-4-piperidinyl) ni- trilotriacetate ; tetrakis (2, 2, 6, 6-tetramethyl-4-piperidinyl) -1, 2, 3, 4-butanetetracarboxylate ; 1, 1'- (1, 2-ethanodiyl) bis- (3, 3, 5, 5-tetramethylpiperazinone ; 4-benzoyl-2, 2, 6, 6-tetra- methylpiperidine ; 4-stearyloxy-2, 2, 6, 6-tetramethylpiperid- ine ; bis (1, 2, 2, 6, 6-pentamethylpiperidyl)-2-n-butyl-2- (2-hyd- roxy-3, 5-di-t-butylbenzyl) malonate ; 3-n-octyl-7, 7, 9, 9-tet- ramethyl-1, 3, 8-triazaspiro [4. 5] decan-2, 4-dione ; bis (1-octyl- oxy-2, 2, 6, 6-tetramethylpiperidyl) sebacate ; bis (1-octyloxy- 2, 2, 6, 6-tetramethylpiperidyl) succinate ; condensation product between N, N'-bis (2, 2, 6, 6-tetramethyl-4-piperidyl) hexameth-

ylenediamine and 4-morpholine-2, 6-dichloro-1, 3, 5-triazine ; condensation product between 2-chloro-4, 6-bis- (4-n-butylam- ino-2, 2, 6, 6-tetramethyl piperidyl)-1, 3, 5-triazine and 1, 2- bis (3-aminopropylamino) ethane ; condensation product between 2-chloro-4, 6-bis- (4-n-butylamino-1, 2, 2, 6, 6-pentamethylpiper- <BR> <BR> <BR> <BR> <BR> idyl)-1, 3, 5-triazine and 1, 2-bis (3-aminopropylamino) ethane ; 8-acetyl-3-dodecyl-7, 7, 9, 9-tetramethyl-1, 3, 8-triazaspiro- [4. 5] decano-2, 4-dione ; 3-dodecyl-l- (2, 2, 6, 6-tetramethyl-4- piperidyl) pyrrolidin-2, 5-dione ; 3-dodecyl-l- (1, 2, 2, 6, 6- pentamethyl-4-piperidyl) pyrrolidin-2, 5-dione ; mixture of he- xadecyloxy-and 4-stearyloxy-2, 2, 6, 6-tetramethylpiperidine ; condensation product between N, N'-bis (2, 2, 6, 6-tetramethyl-4- piperidyl) hexamethylenediamine and 4-cyclohexylamino-2, 6- dichloro-1, 3, 5-triazine ; condensation product between 1, 2- bis (3-aminopropylamino) ethane and 2, 4, 6-trichloro-1, 3, 5-tri- azine, as well as 4-butylamino-2, 2, 6, 6-tetramethylpiperidine (CAS Reg. Nr. [136504-96-6] ; N- (2, 2, 6, 6-tetramethyl-4-piper- idyl)-n-dodecylsuccinimide ; N- (1, 2, 2, 6, 6-pentamethyl-4-pip- eridyl)-n-dodecylsuccinimide ; 2-undecyl-7, 7, 9, 9-tetramethyl- 1-oxa-3, 8-diaza-4-oxospiro [4, 5] decane ; reaction product be- tween 7, 7, 9, 9-tetramethyl-2-cycloundecyl-1-oxa-3, 8-diaza-4- oxospiro [4, 5] decane and epichlorohydrin.

2. 7 Oxamides such as, for example : 4, 4'-dioctyloxyoxanil- ide ; 2, 2'-diethoxyoxanilide ; 2, 2'-dioctyloxy-5, 5'-di-t-but- oxanilide ; 2, 2'-didodecyloxy-5, 5'-di-t-butoxanilide ; 2-eth-

oxy-2'-ethyloxanilide ; N, N'-bis (3-dimethylaminopropyl) oxa- mide ; 2-ethoxy-5-t-butyl-2'-ethoxanilide and its mixtures with 2-ethoxy-2'-ethyl-5, 4'-di-t-butoxanilide ; and mixtures of disubstituted ortho-and para-methoxy oxanilides and mix- tures of disubstituted ortho and para-ethoxy oxanilides.

2. 8 2- (2-hydroxyphenyl)-1, 3, 5-triazines such as, for exam- ple : 2, 4, 6-tris (2-hydroxy-4-octyloxyphenyl)-1, 3, 5-triazine ; 2- (2-hydroxy-4-octyloxyphenyl)-4, 6-bis (2, 4-dimethylphenyl)- 1, 3, 5-triazine ; 2- (2, 4-dihydroxyphenyl)-4, 6-bis- (2, 4-dime- thylphenyl)-1, 3, 5-triazine ; 2, 4-bis- (2-hydroxy-4-propyloxy- phenyl)-6- (2, 4-dimethylphenyl)-1, 3, 5-triazine ; 2- (2-hyd- roxy-4-octyloxyphenyl)-4, 6-bis (4-methylphenyl)-1, 3, 5-triaz- ine ; 2- (2-hydroxy-4-dodecyloxyphenyl)-4, 6-bis (2, 4-dimethyl- phenyl)-1, 3, 5-triazine ; 2- [2-hydroxy-4- (2-hydroxy-3-butyl- oxypropoxy) phenyl]-4, 6-bis (2, 4-dimethyl)-1, 3, 5-triazine ; 2- [2-hydroxy-4- (2-hydroxy-3-octyloxypropyloxy) phenyl]-4, 6-bis- (2, 4-dimethyl)-1, 3, 5-triazine ; 2- (2-hydroxy-4-tridecyloxy- phenyl)-4, 6-bis (2, 4-dimethylphenyl)-1, 3, 5-triazine ; 2- [4- <BR> <BR> <BR> <BR> <BR> <BR> (dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]- 4, 6-bis (2, 4-dimethylphenyl)-1, 3, 5-triazine ;-. [2-hydroxy-4- (2-hydroxy-3-dodecyloxypropoxy) phenyl]-4, 6-bis (2, 4-dimethyl- phenyl)-1, 3, 5-triazine ; 2- (2-hydroxy-4-hexyloxyphenyl)-4, 6- diphenyl-1, 3, 5-triazine ; 2- (2-hydroxy-4-methoxyphenyl)-4, 6- diphenyl-1, 3, 5-triazine ; 2, 4, 6-tris [2-hydroxy-4- (3-butoxy-2- hydroxypropoxy) phenyl]-1, 3, 5-triazine ;

2- (2-hydroxyphenyl)-4- (4-methoxyphenyl)-6-phenyl-1, 3, 5- triazine.

3."Metal-deactivators"such as, for example : N, N'-di-pheny- loxamide, N-salicylal-N'-salicyloyl-hydrazine, N, N'-bis (sa- licyloyl) hydrazine, N, N'-bis (3, 5-di-t-butyl-4-hydroxyphen- ylpropionyl) hydrazine, 3-salicyloylamino-1, 2, 4-triazole, bis (benzylidene) oxalyl dihydrazide, oxanilide, isophthaloyl di- hydrazide, sebacoyl bisphenylhydrazide, N, N'-diacetyladipo- yl dihydrazide, N, N'-bis (salicyloyl) oxallyl dihydrazide, N,- N'-bis (salicyloyl) thiopropionyl dihydrazide.

4. Phosphites and phosphonites such as, for example : tri- phenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris (nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphi- te, tris (2, 4-di-t-butylphenyl) phosphite, diisodecyl pentae- rythritol diphosphite, bis (2, 4-di-t-butyl-phenyl) pentaery- thritol diphosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pen- taerythritol diphosphite, diisodecyloxypentaerythritol di- phosphite, bis (2, 4-di-t-butyl-6-methylphenyl) pentaerythri- tol diphosphite, bis [2, 4, 6-tris (t-butylphenyl)] pentaeryth- ritol diphosphite, tristearyl sorbitol triphosphite, tetra- kis- (2, 4-di-t-butylphenyl)-4, 4'-diphenylylenediphosphonite, 6-iso-octyloxy-2, 4, 8, 10-tetra-t-butyl-12H-dibenzo-[d, g]-1,- 3, 2-dioxaphosphocine, 6-fluoro-2, 4, 8, 10-tetra-t-butyl-12- methyl-dibenzo [d, g]-1, 3, 2-dioxaphosphocine, bis- (2, 4-di-t-

butyl-6-methylphenyl) methylphosphite, bis (2, 4-di-t-butyl-6- methylphenyl) ethylphosphite.

5. Hydroxylamines such as, for example : N, N-dibenzyl-hydr- oxylamine ; N, N-diethylhydroxylamine ; N, N-dioctylhydroxyl- amine ; N, N-dilaurylhydroxylamine ; N, N-ditetradecylhydrox- ylamine ; N, N-dihexadecylhydroxylamine ; N, N-dioctadecylhydr- oxylamine ; N-hexadecyl-N-octadecylhydroxylamine ; N-hepta- decyl-N-octadecylhydroxylamine ; N, N-hydroxylamine deriving from hydrogenated tallow amine.

6. Nitrons such as, for example : N-benzyl-a-phenyl-nitron ; N-ethyl-a-methyl-nitron ; N-octyl-a-heptyl-nitron ; N-lauryl- a-undecyl-nitron ; N-tetradecyl-a-tridecyl-nitron ; N-hexade- cyl-a-pentadecyl-nitron ; N-octadecyl-a-heptadecyl-nitron ; N- hexadecyl-a-heptadecyl-nitron ; N-octadecyl-a-pentadecyl-ni- tron ; N-heptadecyl-a-heptadecyl-nitron ; N-octadecyl-a-hexa- decyl-nitron ; nitron deriving from hydrogenated tallow am- ine.

7. Thiosynergists such as, for example : dilauryl thiodipro- pionate ; distearyl thiodipropionate.

8. Agents which are capable of destroying peroxides such as, for example, esters of P-thiodipropionic acid such as laur- yl, stearyl, myristyl or tridecyl esters, mercaptobenzimi- dazole or zinc salt of 2-mercaptobenzimidazole, zinc dibut- yldithiocarbamate, dioctadecyldisulfide pentaerythritol tet- rakis (ß-dodecylmercapto) propionate.

9. Stabilizers of polyamide such as, for example, copper salts combined with compounds of iodine and/or phosphorous, divalent manganese salts.

10. Basic co-stabilizers such as, for example : melamine, polyvinylpyrrolidone, dicyanodiamide, triallyl cyanurate, derivatives of urea, derivatives of hydrazine, amines, poly- amides, polyurethanes, salts of alkaline metals and salts of earth-alkaline metals of fatty acids with a high molecular weight such as, for example, Ca-stearate, Zn-stearate, Mg- stearate, Mg-behenate, Na-ricinoleate, K-palmitate, antimo- nium-pyrocatecholate, tin-pyrocatecholate, calcium montan- ate.

11. Nucleating agents such as, for example : inorganic sub- stances such as talc, metal oxides (for example, titanium dioxide or magnesium oxide), phosphates, carbonates or sul- fates (preferably of earth-alkaline metals) ; organic com- pounds such as mono-or polycarboxylic acids and their salts (for example, 4-t-butylbenzoic acid, adipic acid, diphenyl- acetic acid, sodium succinate, sodium benzoate) ; polymeric compounds such as ionic copolymers ("ionomers").

12. Fillers and reinforcing agents such as, for example : calcium carbonate, silicates, glass fibres, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite, wood flour and flours or fibres of other natural products, synthetic fibres.

13. Other additives such as, for example : plasticizers, lu- bricants, emulsifying agents, pigments, rheological addi- tives, catalysts, slip agents, optical brighteners, flame- retardants (for example bromurates, chlorurates, phosphor- ates and phosphorous/halogen mixtures), antistatic agents, blowing agents.

14. Benzofuranones and indolinones such as, for example : 3- [4- (2-acetoxyethoxy) phenyl]-5, 7-di-t-butylbenzofuran-2- one ; 5, 7-di-t-butyl-3- [4- (2-stearoyloxyethoxy) phenyl] benzo- furan-2-one ; 3, 3'-bis [5, 7-di-t-butyl-3- [4- (2-hydroxyethoxy) phenyl] benzofuran-2-one] ; 5, 7-di-t-butyl-3- (4-ethoxyphenyl) benzofuran-2-one ; 3- (4-acetoxy-3, 5-dimethylphenyl)-5, 7-di-t- butyl-benzofuran-2-one ; 3- (3, 5-dimethyl-4-pivaloyloxyphen- yl)-5, 7-di-t-butyl-benzofuran-2-one ; or those described in U. S. patents 4, 325, 863, 4, 338, 244, 5, 175, 312, 5, 216, 052 and 5, 252, 643 ; in German patents DE 4, 316, 611, 4, 316, 622 and 4, 316, 876 ; or in European patent applications Nr. 589, 839 and 591, 102.

Some illustrative but non-limiting examples are pro- vided hereunder for a better understanding of the present invention and for its embodiment.

EXAMPLE 1 Light resistance of polypropylene tapes.

100 g of polypropylene in homopolymer powder (Moplen FLF20 of Himont-MFI 12-15 g/10') are mixed with

the following additives : tris (2, 4-di-t-butylphenyl) phosphite (ALKANOX 240 of Great Lakes) : 0. 1 g ; tetrakismethylene (3, 5-di-t-butyl-4-hydroxyhydrocinna- mate) methane (ANOX 20 of Great Lakes) : 0. 1 g ; calcium stearate : 0. 05 g.

The following light stabilizers are added to the above mixture in the quantities indicated in Table 1 : -poly-methylpropyl-3-oxy- [4- (2, 2, 6, 6-tetramethyl) piper- idinyl] siloxane (UVASIL 299 of Great Lakes) ; condensation product between butanedioic acid and 4- hydroxy-2, 2, 6, 6-tetramethyl-1-piperidine-ethanol (LOWI- LITE 62 of Great Lakes) ; bis (2, 2, 6, 6-tetramethyl-4-piperidinyl) sebacate (LOWI- LITE 77 of Great Lakes) ; poly [ (6- [ (1, 1, 3, 3-tetramethylbutyl) amino]-1, 3, 5-tri- azine-2, 4-diyl]-1, 6-hexanediyl [2, 2, 6, 6-tetramethyl-4- piperidinyl) imine]] (CHIMASSORB 944 of Ciba) ; tetramethyl-tetra [ (2, 2, 6, 6-tetramethyl) piperidinyl-4)- 3-oxypropyl] cyclotetrasiloxane (PRODUCT 1).

Each mixture is charged into a Brabender single-screw extruder with a diameter of 19 mm, a length about 25 times the diameter, equipped with a screw and a 2 mm nozzle.

The operating conditions are the following : screw rate : 60 r. p. m. ;

-temperature of the extruder : 260°C.

The product leaves the die in the form of a solid"spa- ghetto"which, after cooling with air at room temperature, is crushed into granules.

The granules of polymer obtained as described above are extruded again using a Plasticizer apparatus operating at a temperature of 270°C and obtaining tapes having a thickness of 40 0 Lm.

The tapes obtained as described above are subjected to accelerated aging using a Xenotest 1200.

The operating conditions are the following : -temperature of the black panel : 50°C ; -relative humidity : 50%.

Some of the tapes are removed at regular intervals from the aging chamber and are subjected to tensile stress, de- termining the impact strength which is obviously reduced during the Xenotest exposure period.

As evaluation criteria of the properties of the addi- tives t 50% was taken, i. e. the exposure time of the tapes to radiation in the Xenotest necessary for having a 50% re- duction in the original impact strength.

Considering that the effectiveness of the light stabi- lizing additive used, with the same concentration, is in di- rect correlation with t 50%, Table 1 demonstrates that PROD- UCT 1 of the present invention, combined with LOWILITE 62, is capable of providing the polypropylene tapes with a bet- ter stabilization.

TABLE 1 LIGHT HALS HALS STABILIZERS CONCENTRATION CONCENTRATION (HALS) (0, 1 %) * (0, 2 %) * t 50% (h) t 50% (h) -480 480 UVASIL 299 2150 3800 LOWILITE 62 1300 2700 LOWILITE 77 1650 3000 CHIMASSORB 944 1850 2900 PRODUCT 1 2000 3500 LOWILITE 62 2500 3750 + PRODOTTO 1 LOWILITE 62 2200 3500 + UVASIL 299 3) LOWILITE 62 1850 3000 + CHIMASSORB 944 'LOWILITE 62 1650 2800 + LOWILITE 77

* : weight percentage with respect to polymer weight ; (1), (2), (3) and (4) : in the mixtures the two components are used in a ratio 1 : 1.

EXAMPLE 2 Light resistance of polypropylene films containing calcium carbonate.

Operating as in Example 1, polypropylene films are pro- duced, having a thickness of 80 pm containing 1. 5% by weight with respect to the weight of the polymer of calcium carbon- ate and 0. 4% by weight with respect to the weight of the polymer of the light stabilizers indicated in Table 2.

The films thus obtained are subjected to accelerated aging in an Atlas CI 65 Weatherometer (WOM) under the fol- lowing operating conditions : -temperature of the black panel : 63°C ; -radiation : 0. 40 W/m2 ; -cycle : 102'/18'.

The films are removed from the radiation chamber at regular intervals and subjected to tensile stress breaking resistance tests as described in Example 1 and the t 50% is calculated.

The results obtained are indicated in Table 2 : also in this case PRODUCT 1 combined with LOWILITE 62 is capable of giving the best results.

TABLE 2

LIGHT STABILIZERS t 50% (h) (HALS) -150 LOWILITE 77 2250 PRODUCT 1 2750 LOWILITE 62 + PRODUCT 1 2900 UVASIL 299 2750 LOWILITE 62 1800 (2) UVASIL 299 + LOWILITE 62 2750 (1) and (2) : in the mixtures the two components are used in a ratio 1 : 1.

EXAMPLE 3 Light resistance of natural polypropylene fibres.

Samples of natural polypropylene fibres [continuous fi- bre 18 deniers per filament (dpf)] containing the following additives : -calcium stearate : 0. 05% by weight with respect to the

weight of the polymer ; -bis (2, 4-di-t-butylphenyl) pentaerythritoldiphosphite (ALKANOX P-24 of Great Lakes) : 0. 1% by weight with re- spect to the weight of the polymer ; -tris (3, 5-di-t-butyl-4-hydroxybenzyl) isocyanurate (ANOX IC-14 of Great Lakes) : 0. 05% by weight with respect to the weight of the polymer ; and 0. 2% by weight with respect to the weight of the polymer of the light stabilizers indicated in Table 3, undergo ac- celerated aging in an Atlas CI 65 Weatherometer (WOM) under the same operating conditions used in Example 2. The fibres are removed from the aging chamber at regular intervals and subjected to tensile stress breaking resistance tests.

T 50%, i. e. the exposure time of the fibres to radia- tion in the WOM necessary for obtaining a 50% reduction in the original impact strength, was taken as evaluation crite- ria of the properties of the additives.

The results obtained are indicated in Table 3.

Table 3 also shows the results relating to the varia- tion in the yellow index (YI), measured with a Macbeth col- orimeter, after exposure of the samples for 56 hours to va- pours of nitrogen oxide produced by the combustion of n- propane. A lower variation in the yellow index is in corre- lation with the better properties of the additive used.

Also in this case, PRODUCT 1 combined with LOWILITE 62 provided the best results.

TABLE 3

LIGHT t 50% (h) YI STABILIZERS (HALS) 180 6, 0 UVASIL 299 800 3, 5 CHIMASSORB 944 700 4, 0 LOWILITE 62 400 1, 8 PRODUCT 1 750 3, 0 LOWILITE 62 + 850 1, 5 PRODUCT 1 LOWILITE 62 + 850 2, 5 UVASIL 299 3) LOWILITE 62 + 750 2, 5 CHIMASSORB 944 (1), (2) and (3) : in the mixtures the two components are used in a 1 : 1 ratio.