GB2354245A - Stabilizer mixtures for polyolefins - Google Patents

Abstract

A stabilizer mixture contains <SL> <LI>A) at least one compound of the formula (VIII) <EMI ID=1.1 HE=31 WI=131 LX=362 LY=593 TI=CF> wherein R<SB>16</SB> is C<SB>1</SB>-C<SB>24</SB>alkyl, and<BR> R<SB>17</SB> is hydrogen, C<SB>1</SB>-C<SB>8</SB>alkyl, -O, -CH<SB>2</SB>CN, C<SB>3</SB>-C<SB>6</SB>alkenyl, C<SB>7</SB>-C<SB>9</SB>phenylalkyl,<BR> C<SB>7</SB>-C<SB>9</SB>phenylalkyl which is substituted on the phenyl radical by C<SB>1</SB>-C<SB>4</SB>alkyl; or C<SB>1</SB>-C<SB>8</SB>acyl; and <LI>B) magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide or an organic salt of zinc or magnesium, or a hydrotalcite; and <LI>C) either <SL> <LI>(C1) an UV absorber or <LI>(C2) a pigment or <LI>(C3) an UV absorber and a pigment. </SL> </SL>

Description

2354245 Stabilizer mixtures This invention relates to a stabilizer mixture

containing A) a certain sterically hindered amine compound, B) a magnesium compound or a zinc compound and C) an UV absorber and/or a pigment, the use of this stabilizer mixture for stabilizing a polyolefin against light-induced degradation and the polyolefin thus stabilized.

Several stabilizer mixtures have already been described in the prior art, for example in US-A-4 929 652, US-A-5 037 870, EP-A-290 388, EP-A-468 923 and EP-A-690 094.

Although numerous stabilizer systems already exist, there is still a need to improve the light stability of polyolefin furthermore.

This invention relates to a stabilizer mixture containing A) at least one compound of the formula (VIII) R16 0 H3C CH3 N-- N-R17 (VI 11) 0 H3C CH3 wherein R,6 is Cl-C24alkyl, and R17is hydrogen, C,-Calkyl, -0-, -CH2CN,C3C6alkenyl,C7-Cgphenylalkyl, C7-C,,phenylalkyl which is substituted on the phenyl radical by C,-C,alkyl; or C,-C"acyl; and B) magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide or an organic salt of zinc or magnesium, or a hydrotalcite; and C) either (Cl) an UV absorber or (C2) a pigment or (M) an UV absorber and a pigment.

Component B) is preferably magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide or an organic salt of zinc or magnesium.

Examples of alkyl having up to 24 carbon atoms are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, npentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1methylheptyl, 3methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl and docosyl.

A preferred embodiment of R17 iSC,-C,alkyl, in particular methyl.

R,6 'SpreferablyC,-Cl4alkyl, in particular C.-C,,alkyl, for example dodecyl.

Examples of C37Calkenyl are allyl, 2-methallyl, butenyl, pentenyl and hexenyl. Allyl is preferred. The carbon atom in position 1 is preferably saturated.

C7-C,Phenylalkyl which is unsubstituted or substituted. by Cj-C,'alkyl on the phenyl radical is, for example, benzyl, phenylethyl, methylbenzyl, dimethylbenzyl, trimethylbenzyl or tert-butylbenzyl. Benzyl is preferred.

C,-C,,acyl is preferably Cl-C,,alkanoy[,C3-C,,alkenoyl or benzoyl. Examples are formyl, acetyl, propionyl, butyryl, pentanoyl, hexanoyl, octanoyl, benzoyl, acrylyl and crotonyl. Acetyl is preferred.

R17 iSpreferably hydrogen,Cl-C4alkyl, allyl, benzyl or acetyl, in particular hydrogen or methyl.

The compounds described as component A) are essentially known (in some cases commercially available) and can be prepared by known processes, for example as described in US-A-4 356 307.

Component A) is preferably CYASORB UV 3581 (RTM) or SANDUVOR 3056 (RTM).

a 0 0..

Preferred stabilizer mixtures are those wherein R, is C,-C,,,alkyl.

Particularly preferred stabilizer mixtures are those wherein component A) is a compound of the formula H25C12 0 H3C CH3 N- N-H (Vill-A) 4 0 H3C CH3 or H25C12 0 H3C CH3 N-- PN-CH3 (Vill-B).

0 H,C CH3 The organic salt of zinc or magnesium defined in component B) is preferably a compound of the formula MeL2 in which Me is zinc or magnesium and L is an anion of an organic acid or of an enol. The organic acid can, for example, be a sulfonic acid, sulfinic acid, phosphonic acid or phosphinic acid, but is preferably a carboxylic acid. The acid can be aliphatic, aromatic, araliphatic or cycloaliphatic; it can be linear or branched; it can be substituted by hydroxyl or alkoxy groups; it can be saturated or unsaturated and it preferably contains 1 to 24 carbon atoms.

Examples of carboxylic acids of this type are formic, acetic, propionic, butyric, isobutyric, caprioic, 2-ethylcaproic, caprylic, capric, lauric, palmitic, stearic, behenic, oleic, lactic, ricinoleic, 2-ethoxypropionic, benzoic, salicylic, 4-butylbenzoic, toluic, 4-dodecylbenzoic, phenylacetic, naphthylacetic, cyclohexanecarboxylic, 4butylcyclohexanecarboxylic or cyclohexylacetic acid. The carboxylic acid can also be a technical mixture of carboxylic acids, for example technical mixtures of fatty acids or mixtures of alkylated benzoic acids.

Examples of organic acids containing sulfur or phosphorus are methanesulfonic, ethanesulfonic, a,(x-dimethylethanesulfonic, nbutanesulfonic, n-dodecanesulfonic, benzenesulfonic, toluenesulfonic, 4nonylbenzenesulfonic, 4-dodecylbenzenesulfonic or cyclohexanesulfonic acid, dodecanesulfinic, benzenesulfinic or naphthalenesulfinic acid, butylphosphonic acid, phenylphosphonic acid, monomethyl or monoethyl phenylphosphonate, monobutyl benzyl phos phonate, dibutylphosphinic acid or diphenylphosphinic acid.

If L is an enolate anion, it is preferably an anion of a P-dicarbonyl compound or of an oacylphenol. Examples of P-dicarbonyl compounds are acetylacetone, benzoylacetone, d ibenzoyl methane, ethyl acetoacetate, butyl acetoacetate, lauryl acetoacetate or aacetylcyclohexanone. Examples of o-acylphenols are 2-acetylphenol, 2-butyroylphenol, 2acetyl-1 naphthol, 2-benzoylphenol or salicylaldehyde. The enolate is preferably the anion of a P-dicarbonyl compound having 5 to 20 carbon atoms.

Preferred examples of component B) are magnesium acetate, laurate and stearate, zinc formate, acetate, oenanthate, laurate and stearate and zinc acetylacetonate and magnesium acetylacetonate.

In a preferred embodiment of this invention component B) as an organic salt of zinc or magnesium is preferably an acetylacetonate or an aliphatic monocarboxylate having, for example, 1 to 24 carbon atoms.

A preferred hydrotalcite is M94,5AI2(OH)l, - C03 - 3.5 H20 ('DHT-4A, 'Kyowa Chemical Industries Co. Ltd.).

The UV absorber in component C) is preferably a 2-(2'hydroxyphenyl)benzotdazole, a 2hydroxybenzophenone, an ester of substituted or unsubstituted benzoic acid, an acrylate, an oxamide, a 2(2-hydroxyphenyl)-1,3,54riazine, a monobenzoate of resorcinol or a formamidine.

The 2-(2'-hydroxyphenyl)benzotriazole is for example 2-(2'-hydroxy-5'methylphenyl)-benzotriazole, 2-(3',5'-di-tert-butyl-2'hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3tetramethylbutyl)phenyl)benzotdazole, 2-(3',5'-ditert-butyl-2'hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl- 2'-hydroxy-5'methylphenyl)-5-chloro-benzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'hydroxyphenyl)benzotdazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(cc, cc-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, mixture of 2-(3'tertbutyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-be nzotriazole, 2-(3'-tertbutyl-5'-[2-(2-ethylhexyloxy)-carbonylethyl]-2'hydroxyphenyl)-5 -chloro-benzotriazole, 2-(3'tert-butyl-2'-hydroxy-5'-(2methoxycarbonylethyl)phenyl)-5-chioro-ben zotriazole, 2-(3'-tertbutyl-2'hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl2'-hydroxy5'-(2-octyloxycarbonylethyl)phenyl)benzotdazole, 2-(3'-tertbutyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'methylphenyl)benzotriazole, 2-(3'4ert-butyl-2'-hydroxy-5'-(2isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2'-methylene-bis[4-(1,1,3, 3-tetramethylbutyl)-6-benzotriazole-2-yI phenol] or the transesterification product of 2-[3'-tert-butyl-5'-(2methoxycarbonylethyl)-2'-hydroxyphenyl]21-1-benzotriazole with polyethylene glycol 300;, where R = 3'-tert-butyl-4'-hydroxy-5-2Hbenzotriazol-2-ylphenyl.

2-(3',5'-Di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'tert-butyl-2'-hydroxy-5'methylphenyl)-5-chloro-benzotriazole and 2-(3',5'di4ert-amyl-2'-hydroxyphenyl)benzotriazole are preferred.

The 2-hydroxybenzophenone is for example the 4-hydroxy, 4-methoxy, 4octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzy[oxy, 4,2',4-trihydroxy or 2'hydroxy-4,4'-dimethoxy derivatives.

2-Hydroxy-4-octyloxybenzophenone is preferred.

The ester of a substituted or unsubstituted benzoic acid is for example 4tert-butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl) resorcinol, benzoyl resorcinol, 2,4-di-tertbutylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tertbutyl-4-hydroxybenzoate or 2-methyl-4,6-di-tert-butylphenyI 3,5-di-tertbutyl-4-hydroxybenzoate.

2,4-Di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate and hexaclecyl 3,5-di-tert-butyl-4hydroxybenzoate are preferred.

The acrylate is for example ethyl (x-cyano-P,P-diphenylacrylate, isooctyl a-cyano-P,P-diphenylacrylate, methyl a-carbomethoxycinnamate, methyl (Xcyano-P-methyl-p-methoxycinnamate, butyl (x-cyano-p-methyl-p-methoxycinnamate, methyl a-carbomethoxy-pmethoxycinnamate or N-(P-carbomethoxy-pcyanovinyl)-2-methylindoline.

The oxamide is for example 4,4'-dioctyloxyoxanilide, 2,2diethoxyoxanilide, 2,2'-dioctyloxy5,5'-di-tert-butoxanilide, 2,2'didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyl-2-ethoxanilide or its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide or mixtures of ortho- and para-methoxydisubstituted oxanilides or mixtures of o- and p-ethoxy-disubstituted oxanilides.

The 2-(2-hydroxyphenyl)-1,3,5-triazine is for example 2,4,6-tds(2-hydroxy4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6bis(2,4-dimethylphenyl)-1,3,5-triazine, 2(2,4-dihydroxyphenyl)-4,6-bis(2, 4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-propyloxyphenyl)-6(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6bis(4methylphenyl)-1,3,5-tdazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6bis(2,4-dimethylphenyl)1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)4,6-bis(2,4-dimethylphenyl)-1,3,5-triazi ne, 2[2-hydroxy-4-(2-hydroxy-3butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-teiazine, 2[2hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bis(2,4-dimethyl)1,3,5-triazine, 2-[4(dodecyloxy/tridecyloxy- 2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,35-triazine, 2-[2-hydroxy4-(2hydroxy-3-dodecyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl phenyl)-1,3,5tdazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2hydroxy-4-methoxyphenyl)-4,6-diphen1-1,3,5-tNazine, 2,4,6-tris[2-hydroxy4-(3-butoxy-2hydroxy-propoxy)phenyl]-1,3,5-triazine or 2-(2hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-tdazine.

2-(2-Hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine and 2-(2-hydroxy4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine are preferred.

The monobenzoate of resorcinol is for example the compound of the formula 0 11 0 a OH The formamidine is for example the compound of the formula 0 C H5 I I '/ 2 H 5C 2 O-C NCH-N The UV absorber in component C) is in particular a 2-(2'- hydroxyphenyl)benzotriazole, a 2-hydroxybenzophenone or a 2-(2- hydroxyphenyl)-1,3,5-triazine.

Component C) is preferably an UV absorber.

The pigment in component C) may be an inorganic or organic pigment.

Examples of inorganic pigments are titanium dioxide, zinc oxide, carbon black, cadmium sulfide, cadmium selenide, chromium oxide, iron oxide, lead oxide and so on.

Examples of organic pigments are azo pigments, anthraquinones, phthalocyanines, tetrachloroisoindolinones, quinacridones, isoindolines, perylenes, pyrrolopyrroles (such as Pigment Red 254) and so on.

As a pigment in component C), all pigments described in "G5chter/Maller: Plastics Additives Handbook, 3rd Edition, Hanser Publishers, Munich Vienna New York", page 647 to 659, point 11.2.1.1 to 11.2.4.2 can be used.

A particular preferred pigment is titanium dioxide.

A further preferred embodiment of this invention is a stabilizer mixture containing A) a compound of the formula (VIII-A) or (Vill-B), B) magnesium stearate or zinc stearate and C) the compound OH C(CH3)3 Cl', N N N CH3 OH C(CH 3)3 C",,aN \N N C(CH3)3 or Ti02- The stabilizer mixture according to the present invention is useful for stabilizing polyolefins. Examples of suitable polyolefins are shown in the following.

1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, polybut-l-ene, poly-4-methylpent-l-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example high density polyethylene (HDPE), high density and high molecular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight polyethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE).

Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, preferably polyethylene and polypropylene, can be prepared by different, and especially by the following, methods:

a) radical polymerisation (normally under high pressure and at elevated temperature).

b) catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups lVb, Vb, Vib or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either 7r- or a-coordinated. These metal complexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(l 11) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups la, Ila and/or Ilia of the Periodic Table. The activators may be modified conveniently with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips (RTM)j Standard Oil Indiana, Ziegler (-Nafta), TNZ (DuPont), metallocene or single site catalysts (SSC).

2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE).

3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/but-l-ene copolymers, propylene/isobutylene copolymers, ethylene/but-l-ene copolymers, ethylene/hexene copolymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetate copolymers and their copolymers with carbon monoxide or ethylene/acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with one another and with polymers mentioned in 1) above, for example polyp ropyie ne/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EAA), LLDPE/EVA, LLDPE/EAA and alternating or random polyalkylene/carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides.

The invention therefore furthermore relates to a composition containing a polyolefin and the novel stabilizer mixture.

The polyolefins listed above under point 1 are preferred. Polyethylene and polypropylene as well as a copolymer of polyethylene or polypropylene are particularly preferred.

The components of the novel stabilizer mixture ran be added to the material to be stabilized either individually or mixed with one another. Component (A) is preferably present in an amount of 0.01 to 5 %, in particular 0.05 to 1 %; component (B) is preferably present in an amount of 0.005 to 1 %, in particular 0.025 to 0.2 %; component (Cl) is preferably present in an amount of 0.01 to 1 %, component (C2) is preferably present in an amount of 0.01 to 10 % and component (M) is preferably present in an amount of 0.01 to 10 is % by weight, relative to the material to be stabilized.

The ratio of the UV absorber to the pigment in component (M) is preferably 2:1 to 1:10.

The ratio of the components (A):(B) is preferably 30:1 to 1:30, for example 20:1 to 1:20 or 20:1 to 1: 10.

The ratio of the components (A):(C,) is preferably 1:20 to 30:1, for example 1:10 to 20:1 or 1: 5 to 20: 1.

The ratio of the components (A): (C2) is preferably 1: 30 to 30: 1, for example 1:20 to 20:1 or 1: 10 to 10: 1.

The ratio of the components (A):(C3) is preferably 1:30 to 30:1, for example 1:20 to 20:1 or 1: 10 to 10: 1.

The novel stabilizer mixture or the individual components thereof can be incorporated into the polyolefin by known methods, for example before or during shaping or by applying the dissolved or dispersed compounds to the polyolefin, if necessary with subsequent evaporation of the solvent. The individual components of the novel stabilizer mixture can be added to the materials to be stabilized in the form of a powder, granules or a masterbatch, which contains these components in, for example, a concentration of from 2.5 to 25% by weight.

If desired, the components of the novel stabilizer mixture can be melt blended with each other before incorporation in the polyolefin.

The novel stabilizer mixture or its components can be added before or during the polymerization or before the crosslinking.

The materials stabilized in this way can be used in a wide variety of forms, for example as films, fibres, tapes, moulding compositions, profiles or as binders for paints, adhesives or putties.

The stabilized polyolefin of the invention may additionally also contain various conventional additives, for example:

1. Antioxidants 1.1. Alkylated monophenol, for example 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-d i-tert-butyl-4-ethyl phenol, 2,6- di-tert-butyl-4-n-butylphenol, 2,6-d i-tert-butyl-4-isobutyl phenol, 2,6- d icyclopentyl-4-methyl phenol, 2-(amethylcyclohexyl)-4,6-dimethyl phenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert- butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6- (l'-methylundec-l'-yl)phenol, 2,4-dimethyl-6-(l'-methyl- heptadec-l'-yl)phenol, 2,4-dimethyl-6-(l'-methyltridec-l'-yl)phenoI and mixtures thereof.

1.2. Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tertbutylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl6-ethyl phenol, 2,6-didodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tertbutyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tertamylhydroquinone, 2,6diphenyl-4-octadecyloxyphenol, 2,6-di-tertbutylhydroquinone, 2,5-di-tert-butyl-4hydroxyanisole, 3,5-di-tert-butyl-4hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-ditert-butyl-4-hydroxyphenyl) adipate.

1.4. Tocopherols, for example a-tocopherol, P-tocopherol, 7-tOcOpherol, 5tocopherol and mixtures thereof (Vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example 2,2'-thiobis(6-tertbutyl-4methylphenol), 2,2'-th iobis(4-octyl phenol), 4,4'-thiobis(6-tertbutyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'thiobis-(3,6-di-sec-amylphenol), 4,4'bis-(2,6-dimethyl-4-hydroxyphenyl) disulfide.

1.6. Alkylidenebisphenols, for example 2,2'-methylenebis(6-tert-butyl4methylphenol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'methylenebis[4methyl-6-(a-methylcyclohexyl)phenol], 2,2-methylenebis(4methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl-4-methylphenol), 2, 2'-methylenebis(4,6-di-tertbutylphenol), 2,2'-ethylidenebis(4,6-di-tertbutyI phenol), 2,2'-ethylidenebis(6-tertbutyl-4-isobutylphenol),.2,2'methylenebis[6-(a-m ethylbenzyl)-4-nonylphenol], 2,2'methylenebis[6-(a,ad imethyl benzyl)-4-nonyl phenol], 4,4'-methylenebis(2,6-ditertbutylphenol), 4,4'-methylenebis(6-tert-butyl-2-methyI phenol), 1,1bis(5-tert-butyl-4hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5methyl-2-hydroxybenzyl)-4methylphenol, 1,1,3-ths(5-tert-butyl-4-hydroxy-2methylphenyl)butane, 1,1-bis(5tert-butyl-4-hydroxy-2-methyl-phenyl)-3-ndodecylmercaptobutane, ethylene glycol bis[3,3-bis(3'-tert-butyl-4'hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5methyl-phenyl)dicyclopentadiene, bis[2-(3'-tert-butyl-2'-hydroxy-5'methylbenzyl)-6tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5dimethyl-2-hydroxyphenyl)butane, 2,2-bis-(3,5-di-tert-butyl-4hydroxyphenyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-4-ndodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy2methylphenyl)pentane.

1.7. 0-, N- and S-benzyl compounds, for example 3,5,3',5'-tetra-tertbutyl-4,4'dihydroxydibenzyl ether, octadecyl-4-hydroxy-3,5dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tertbutylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4hyd roxybenzyl)a mine, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3, 5-di-tert-butyl-4-hydroxybenzyl)sulfide, isooctyl-3,5di-tert-butyl4hydroxybenzy1mercaptoacetate.

1.8. Hydroxybenzylated malonates, for example dioctadecyl-2,2-bis-(3,5-ditert-butyl-2-hydroxybenzyl)-malonate, di-octadecyl-2-(3-tert-butyl-4hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bis-(3,5-ditert-butyl-4hydroxybenzyl)malonate, bis[4-(1,1,3,3tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tertbutyl-4hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compound, for example 1,3,5-tris-(3,5-di-tertbutyl-4hydroxybenzyl)-2,4,6-tdmethylbenzene, 1,4-bis(3,5-di-tert-butyl-4hydroxybenzyl)2,3,5,6-tetramethyl benzene, 2,4,6-tris(3,5-di-tert-butyl-4hydroxybenzyl)phenol.

1. 10. Triazine Compounds, for example 2,4-bis(octylmercapto)-6-(3,5-ditert-butyl4-hydroxyanilino)-1,3,5-tdazine, 2-octylmercapto-4,6-bis(3,5-ditert-butyl-4hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5di-tert-butyl-4hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tis(3,5-di-tertbutyl-4-hydroxyphenoxy)1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4hydroxybenzyl)isocyanurate, 1,3,5tris(4-tert-butyl-3-hydroxy-2,6dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tertbutyl-4hydroxyphenylethyl)-1,3,5-tdazine, 1,3,5-tris(3,5-di-tert-butyl4hydroxyphenylpropionyl)-hexahydro-1,3,5-tria zine, 1,3,5-tds(3,5dicyclohexyl-4hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4hydroxybenzylphosphonate, d iethyl-3,5-d i-tert-butyl-4-hyd roxybenzyl phos phonate, dioctadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy3methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tertbutyl-4-hydroxybenzylphosphonic acid.

1. 12. Acylaminophenols, for example 4-hydroxylauranilide, 4hydroxysteara nil id e, octyl N-(3,5-di-tert-butyl-4hydroxyphenyl)carbamate.

1. 13. Esters:)f L-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, ioctanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N, N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-lphospha-2,6,7trioxabicyclo[2.2.2]octane.

1.14. Esters ofp-(5-tert-butyl-4-hyd roxy-3-methyl phenyl)prop ionic acid with monoor polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'-bis(hydroxyethyl)oxamide, 3thiaundecanol, 3thiapentadecanol, trimethylhexanediol, trimethylol propane, 4hydroxymethyl-l-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1. 15. Esters of _0-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6hexanediol, 1,9-nonanediol, ethylene glycol, 1,2propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3thiapentadecanol, trimethylhexanediol, trimethylol propane, 4-hydroxymethyl-lphospha-2,6,7trioxabicyclo[2.2.2]octane.

1. 16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyI acetic acid with monoor polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hyd roxyethyl)isocyanu rate, N,N'bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3thiapentadecanol, trimethylhexanediol, trimethylol propane, 4-hydroxymethyl-1phospha-2,6,7tdoxabicyclo[2.2.2]octane.

1.17. Amides of 0-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g. N,N'bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamine, N,N'bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamine, N, N'-bis(3,5-ditert-butyl-4-hydroxyphenylpropionyl)hydrazine.

1. 18. Ascorbic acid (vitamin C) 1. 19. Aminic antioxidants, for example N,N'-di-isopropyl-p- phenylenediamine, N,N'di-sec-butyl-p-phenylenediamine, N,N'-bis(1,4dimethylpentyl)-pphenylenediamine, N,N'-bis(l-ethyl-3-methylpentyl)-pphenylenediamine, N,N'bis(l-methylheptyl)-p-phenylenediamine, N,N'dicyclohexyl-p-phenylenediamine, N, N'-d i phenyl-p-phenylened ia mine, N, N'-bis(2-naphthyl)-p-phenylenediamine, Nisopropyl-N'-phenyi-pphenylenediamine, N-(1,3-dimethylbutyl)-N'-phehyl-pphenylenediamine, N-(lmethylheptyl)-N'-phenyl-p-phenylenediamine, Ncyclohexyl-N'-phenyi-pphenylenediamine, 4-(p-toluenesulfamoyl)diphenylamine, N,N'-dimethyl-N,N'di-sec-butyl-p-phenylenediamine, diphenylamine, N-ally1diphenylamine, 4isopropoxydiphenylamine, N-phenyl-l-naphthylamine, N-(4-tertoctylphenyl)l-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, for example p,p'-di-tert-octyidiphenylamine, 4-n-butylaminophenol, 4butyrylaminophenol, 4-nonanoylamino-phenol, 4-dodecanoylaminophenol, 4octadecanoylaminophenol, bis(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'diaminodiphenylmethane, N,N,N',N'-tetramethyl-4,4'-diaminodiphenylmethane, 1,2-bis[(2methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane, (otolyl)biguanide, Bis[4-(l',3'-dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-l-naphthylamine, a mixture of mono- and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyidiphenylamines, a mixture of mono- and dialkylated isopropyl/isohexyldiphenylamines, a mixture of mono- and dialkylated tertbutyldi phenyla mines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono- and dialkylated tert-butylltertoctylphenothiazines, a mixture of mono- and dialkylated tert-octylphenothiazines, N-allylphenothiazin, N,N,N',N'-tetraphenyl-1,4-diaminobut2-ene, N,N-bis(2,2,6,6-tetramethyl-piperid-4-yl-hexamethylenediamine, bis(2,2,6,6-tetramethylpiperid-4-yl)sebacate, 2,2,6,6tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol.

2. UV absorbers and light stabilisers 2.1 Nickel compounds, for example nickel complexes of 2,2'-thio-bis-[4-(1, 1,3,3tetramethylbutyl)phenol],such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N- cyclohexyidiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. the methyl or ethyl ester, of 4-hydroxy-3,5-di- tert-butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2- hydroxy-4-methylphenyl undecylketoxime, nickel complexes of 1-phenyl-4lauroyl-5-hydroxypyrazole, with or without additional ligands.

2.2 Sterically hindered amines, for example bis(2,2,6,64etramethyl4piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis(1, 2,2,6,6pentamethyl-4-piperidyl)sebacate, bis(l-octyloxy-2,2,6,6tetramethyl-4pipeddyl)sebacate, bis(1,2,2,6,6-pentamethyl4-pipeidyl) nbutyl-3,5-di-tert-butyl4-hydroxybenzylmalonate, the condensate of 1-(2hydroxyethyl)-2,2,6,6tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,N'bis(2,2,6,6-tetramethyl-4pipeddyl)hexamethylenediamine and 4-tert-octylamino2,6-dichloro-1,3,5triazine, t(is(2,2,6,6-tetramethyl-4-piperidyl)nitrilotdacetate, tetrakis(2,2,6,6-tetramethyl-4-pipeeidyl)-1,2,3,4-butane-tetracarboxylate, 4benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2hydroxy-3,5-di-tert-but yl- I benzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-tdazaspiro[4.5]decan- 2,4dion, bis(l-octyloxy-2,2,6,6-tetramethylpipeddyl)sebacate, bis(1octyloxy-2,2,6,6tetramethylpiperidyl)succinate, the condensate of N,N'bis-(2,2,6,6-tetramethyl-4piperidyl)hexamethylenediamine and 4-morpholino2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-nbutylamino-2,2,6,6-tetramethylpiperidyI)-1,3,5triazine and 1,2-bis(3aminopropylamino)ethane, the condensate of 2-chloro-4,6di-(4-n-butylamino1,2,2,6,6-pentamethylpipeddyl)-1,3,5-triazine and 1,2-bis(3aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8tdazaspiro[4.5]decane-2,4-dione, 3-dodecyl-l-(2,2,6,6-tetramethyl-4piperidyl)pyrrolidin-2,5-dione, 3-dodecyl-l-(1,2,2,6,6-pentamethyl-4piperidyl)pyrrolidine-2,5dione, a mixture of 4-hexadecyloxy- and 4stearyloxy-2,2,6,6-tetramethylpiperidine, a condensation product of N,N'bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4cyclohexylamino-2,6-dichloro-1,3,5-tdazine, a condensation product of 1,2bis(3-aminopropylamino)ethane and 2,4,6-trichloro-1,3,5-tdazine as well as 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No. [136504-96- 61); N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimid, N-(1,2,2,6, 6-pentamethyl4-piperidyl)-n-dodecylsuccinimid, 2-undecyl-7,7,9,9tetramethyl-l-oxa-3,8-diaza-4oxo-spiro[4,5]decane, a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-loxa-3,8-diaza-4-oxospiro (4,5]decane and epichlorohydrin.

3. Metal deactivators, for example N,N'-diphenyloxamide, N-salicylal-N'salicyloyl hydrazine, N,N'-bis(salicyloyl) hydrazine, N,N'-bis(3,5-ditert-butyl-4-hydroxyphenylpropionyl) hydrazine, 3-salicyloylamino-1,2,4triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyloyi)oxalyl dihydrazide, N,N'bis(salicyloyl)thiopropionyI dihydrazide.

4. Phosphites and phosphonites, for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-ditert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tertbutylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)- pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,47ditert-butyl-6-methylphenyl)pentaerythritoI diphosphite, bis(2,4, 6-tris(tertbutylphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenz[d,g]-1, 3,2-dioxaphospho cin, 6-fluoro-2,4,8,10-tetra-tert-butyl12-methyldibenz[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6methylphenyl)methylphosphite, bis(2,4-di-tert-butyl-6methylphenyl)ethylphosphite.

5. Hydroxylamines, for example, N,N-dibenzylhydroxylamine, N,Ndiethylhydroxylamine, N,N-dioctyihydroxylamine, N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine, N,Ndioctadecylhydroxylamine, Nhexadecyl-N-octadecylhydroxylamine, Nheptadecyl-N-octadecylhydroxylamine, N, N-d ialkylhyd roxyla mine derived from hydrogenated tallow amine.

6. Nitrones, for example, N-benzyl-alpha-phenyl-nitrone, N-ethyl-alphamethylnitrone, N-octyl-alpha-heptyl-nitrone, N-lauryl-alpha-undecylnitrone, N-tetradecyl-alpha-tridecyl-nitrone, N-hexadecyl-alphapentadecyl-nitrone, N-octadecyl-alphaheptadecyl-nitrone, N-hexadecylalpha-heptadecyl-nitrone, N-ocatadecyl-alphapentadecyl-nitrone, Nheptadecyl-alpha-heptadecyl-nitrone, N-octadecyl-alphahexadecyl-nitrone, nitrone derived from N,N-dialkylhydroxylamine derived from hydrogenated tallow amine.

7. Thiosynergists, for example, dilauryl thiodipropionate or distearyl thiodipropionate.

8. Peroxide scavengers, for example esters of P-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole, dioctadecyl disulfide, pentaerythritol tetrakis(Pdodecylmercapto)propionate.

9. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, poiyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids for example calcium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or tin pyrocatecholate.

10. Nucleating agents, for example, inorganic substances such as talcum, metal oxides such as titanium dioxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals; organic compounds such as mono- or polycarboxylic acids and the salts thereof, e. g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or sodium benzoate; polymeric compounds such as ionic copolymers ("ionomers").

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

12. Other additives, for example, plasticisers, lubricants, emulsifiers, pigments, rheology additives, catalysts, flow-control agents, optical brighteners, flarneproofing agents, antistatic agents and blowing agents.

13. Benzofuranones and indolinones, for example those disclosed in USA4325863, US-A-4338244, US-A-5175312, US-A-5216052, US-A-5252643, DEA4316611, DE-A-4316622, DE-A-4316876, EP-A-0589839 or EP-A-0591102 or 3[4(2-acetoxyethoxy)phenyll-5,7-di-tert-butyl-benzofuran-2-one, 5,7-di-tertbutyl-3[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one, 3,3'-bis[5,7-ditert-butyl-3-(4-[2hydroxyethoxy]phenyl)benzofuran-2-one], 5,7-di-tertbutyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4-acetoxy-3,5dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2one, 3-(3,5-dimethyl-4pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

The weight ratio of the total amount of components A), B) and C) to the conventional additives can be, for example, from 1:0.1 to 1:5.

The invention furthermore relates to the use of the novel stabilizer mixture for stabilizing a polyolefin against light-induced degradation.

The examples below illustrate the invention in greater detail. All percentages and parts are by weight, unless stated otherwise.

Stabilizers used in Examples 1 and 2:

Compound (Vill-A):

H25C12 0 H3CCH3 N- N - H 0 1-13C CH3 Compound (Vill-13):

H25C12 0 H3 CH3 N- N-CH3 0 H3C CH3 Compound ()(X):

F13C CH3 --0 - N -CH2CH, OOC-CH2CHi-CO- H3 c CH3 The mean value of n is 5.1.

Compound (C):

OH C(CH3)3 N, N N C(CH3)3 Example 1: Light stabilization in polypropylene homopolymer films. 100 parts of polypropylene homopolymer powder are homogenized with 0.05 part of pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 0.05 part of tris(2,4-di-tert-butylphenyl) phosphite and with the stabilizers indicated in Tables 1 and 2 in a Brabender plastograph (RTM) at 200 OC for 10 minutes. The composition thus obtained is removed from the compounder as rapidly as possible and compressed in a toggle press to give a sheet with a thickness of 2-3 mm. A piece of the resultant press-moulding is cut out and pressed between two high-gloss hard aluminiurn foils for 6 minutes at 260 'C using a laboratory hydraulic press to give a film with a thickness of 0.5 mm, which is immediately cooled in a water-cooled press. Sections each measuring 60 mm x 25 mm are then punched out of this 0.5 mm film and are exposed in a WEATHER-OMETER Ci 65 (black panel temperature 63+2 OC, without water- spraying). These test specimens are removed from the exposure apparatus at regular intervals and tested for their carbonyl content in an IR spectrometer. The increase in the carbonyl extinction on exposure is a measure of the photooxidative, degradation of the polymer and is known from experience to be associated with a deterioration in the mechanical properties.

The time (To., measured) needed to reach a carbonyl extinction of 0.1 is shown in Tables 1 and 2.

Table 1: Light stabilization action in polypropylene homopolymer films.

Light stabilizer T0.1 measured in hours 0.05 % of (VIII-A), 0.1 % of magnesium stearate and 0.1 % of (C) 2700 0.05 % of (Vill-B), 0.1 % o f magnesium stearate and 0.1 % of (C) 2320 Comparison:

Stabilizer mixture according to US-A-4 929 652 0.05 % of (XX), 0.1 % of magnesium stearate and 0.1 % of (C) 1620 Table 2: Light stabilization action in polypropylene homopolymer films.

Light stabilizer T0.1 measured in hours 0.05 % of (Vill-A), 0.1 % of zinc stearate and 0.5 % of TiO2 (rutile) 2700 0.05 % of.(VI 11-13), 0. 1 % of zinc stearate and 0.5 % of Ti02 (rutile) 2560 Comparison:

Stabilizer mixture according to US-A-4 929 652 0.05 % of (XX), 0.1 % of zinc stearate and 0.5 % of Ti02 (rutile) 1230 Example 2: Light stabilization in polypropylene block copolymer films. 100 parts of polypropylene block copolymer powder are homogenized with 0. 05 part of pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 0.10 part of tris(2,4-di-tert-butylphenyl) phosphite and with the stabilizer mixture indicated in Table 3 in a Brabender plastograph (RTM) at 200 IC for 10 minutes. The composition thus obtained is removed from the compounder as rapidly as possible and compressed in a toggle press to give a sheet with a thickness of 2-3 mm. A piece of the resultant press-moulding is cut out and pressed between two high-gloss hard aluminium foils for 6 minutes at 260 OC using a laboratory hydraulic press to give a film with a thickness of 0.5 mm, which is immediately cooled in a water-cooled press. Sections each measuring 60 mm x 25 mm are then punched out of this 0.5 mm film and are exposed in a WEATHER-OMETER Ci 65 (black panel temperature 63+2 'IC, without water-spraying). These test specimens are removed from the exposure apparatus at regular intervals and tested for their carbonyl content in an IR spectrometer. The increase in the carbonyl extinction on exposure is a measure of the photooxidative degradation of the polymer and is known from experience to be associated with a deterioration in the mechanical properties.

The time (To., measured) needed to reach a carbonyl extinction of 0.1 is shown in Table 3.

Table 3:

Stabilizer mixture T0.1 measured in hours 0.05 % of (Vill-A), 0.1 % of magnesium stearate and 0.1 % of (C) 6760 0.05 % of (VI I I-B), 0. 1 % of magnesium stearate and 0. 1 % of (C) 5840 Comparison:

Stabilizer mixture according to US-A-4 929 652 0.05 % of (XX), 0.1 % of magnesium stearate and 0.1 % of (C) 4400

Claims (15)

Claims:

1. A stabilizer mixture containing A) at least one compound of the formula (Vill) R 0 H3C CH3 N-- N - R 17 (Vill) 0 F13C CH3 wherein R,6 is Cl-C24alkyl, and R17 is hydrogen, C,-C8alkyl, -0-, -CH2CN, C3-C6alkenyl, C7-C9phenylalkyl, C7-C9phenylalkyl which is substituted on the phenyl radical by Cj-C4alkyl; or C,-C.acyl; and B) magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide or an organic salt of zinc or magnesium, or a hydrotalcite; and C) either (Cl) an UV absorber or (C2) a pigment or (M) an UV absorber and a pigment.

2. A stabilizer mixture according to claim 1 wherein component B) is magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide or an organic salt of zinc or magnesium.

3. A stabilizer mixture according to claim 1 wherein R17 is hydrogen, C,C4alkyl, allyl, benzyl or acetyl.

4. A stabilizer mixture according to claim 1 wherein R17 is hydrogen or methyl.

5. A stabilizer mixture according to claim 1 wherein R,, is Cl-C,4alkyl.

6. A stabilizer mixture according to claim 1 wherein component A) is a compound of the formula H25C12 0 1-13C CH3 N N-H (VIII-A) P 0 H3 C CH3 or H25C12 0 H3CCH3 N- PN-CH3 (Vill-B).

0 H3C CH3

7. A stabilizer mixture according to claim 1 wherein the organic salt of zinc or magnesium is an acetylacetonate or an aliphatic monocarboxylate.

8. A stabilizer mixture according to claim 1 wherein the UV absorber is a 2-(2'hydroxyphenyl)benzotriazole, a 2-hydroxybenzophenone, an ester of substituted or unsubstituted benzoic acid, an acrylate, an oxamide, a 2(2-hydroxyphenyl)1,3,5-triazine, a monobenzoate of resorcinol or a formamidine.

9. A stabilizer mixture according to claim 1 wherein the UV absorber is a 2-(2'-hydroxyphenyl)benzotriazole, a 2-hydroxybenzophenone or a 2-(2hydroxyphenyl)-1,3,5-t(iazine.

10. A stabilizer mixture according to claim 1 wherein the pigment is titanium dioxide.

11. A stabilizer mixture according to claim 1, containing as component C) an UV absorber.

12. A stabilizer mixture according to claim 6 wherein component B) is magnesium stearate or zinc stearate and component C) is the compound OH C(CH 3)3 N N CH 3 OH C(CH A N CI C(CH A or Ti02-

13. A composition containing a polyolefin and a stabilizer mixture according to claim 1.

14. A composition according to claim 13 wherein the polyolefin is polyethylene or polypropylene or a copolymer of polyethylene or polypropylene.

15. A method for stabilizing a polyolefin against light-induced degradation, which comprises adding to the polyolefin a stabilizer mixture according to claim 1.