WO2004031282A1

WO2004031282A1 - Synergistic combinations of phenolic antioxidants

Info

Publication number: WO2004031282A1
Application number: PCT/IB2003/004359
Authority: WO
Inventors: Ernesto Dongiovanni; Christoph Kroehnke; Tania Weyland
Original assignee: Clariant International Ltd; Clariant Finance (Bvi) Limited
Priority date: 2002-10-01
Filing date: 2003-09-30
Publication date: 2004-04-15
Also published as: TW200407374A; AU2003265080A1; GB0222670D0

Abstract

The invention relates to synergistic combinations of certain phenolic antioxidants in thermoplastic polymers, especially in polyamides and other thermoplastic molding materials. The instant combinations lead to better resistance against oxidativie degradation as measured in terms of yellowness index (YI), color and other technically important parameters as known in the art.

Description

SYNERGISTIC COMBINATIONS OF PHENOLIC ANTIOXIDANTS

The invention relates to synergistic combinations of phenolic antioxidants in engineering plastics and other thermoplastic molding materials especially polyamides. The invention also relates to combinations of such synergistic mixtures with organo- phosph(on)ites.

The usability and lifetime of plastic articles is influenced by numerous parameters such as mechanical properties, density, molar mass and mass distribution of the polymer. Depending on the final use and the local conditions (temperature, stress, and environmental influences) during the service time, a lifetime of up to several decades must be guaranteed which can only be reached with the appropriate stabilizers and stabilizer combinations. Their contribution can be determined under accelerated test conditions at elevated temperatures.

As an important technical criterion the color measured as yellowness index (YI) is used to assess the stabilization of polymer articles like those made out of polyamide. Effects in the polymer matrix e.g. change in cristallinity, free volume, morphology, and co- efficient of diffusion and reaction kinetics cause changes in the degradation mechanism.

One of the decisive criteria preventing rapid oxidative degradation of polymer articles is the use of long-term stabilizers such as sterically hindered phenols (1). Their efficiency is depending on the compatibility, the solubility, the mobility and the migration of additives in the resin (2). Technically important polymers like polyamides have to stand more stringent test conditions for use in specific technical areas. The use of phenolic antioxidants inhibits early autoxidation especially during thermal treatment and therefore enables excellent retention of physical properties. Especially in the various types of aliphatic polyamides, phenolic antioxidants improve the initial color after polyconden- sation and processing. Those stabilizers can be added already during the polyconden- sation prior to the termination of the reaction (3).

The following publications refer to the above mentioned problems: (1 ) F.Gugumus in "Plastics Additives, 3^rd. ed., editors R.Gachter and H.Mϋller, C.Hanser Publishing Company, Munich, pp.1 (1990)

(2) N.C.Billingham, D.C.Bott and A.S.Manke in "Developments in Polymer Degradation", 3^rd edition, editor Grassie, Applied Science Publishers, London, pp.63 (1981 )

(3) H.Zweifel in "Stabilization of Polymeric Materials", 1^st ed., Springer Publishing Company, Berlin, Heidelberg, New York, pp.94 (1998)

This invention relates primarily to the synergistic behavior and advantageous use of synergistic combinations of hydrolytically stable with hydrolytically less stable phenolic antioxidants for long-term thermal stabilization. The claimed combinations of those sterically hindered phenols surprisingly offer the possibility to outperform the state of the art in terms of technical key parameters. A second aspect of the invention are formulations consisting of the mentioned phenol-combinations and sterically hindered phosph(on)ites which give rise to a further improved color during long term use at elevated temperatures.

Phenolic antioxidants have been used in combination with organo-phosphites or organo-phosphonites and sometimes with other stabilizers like alpha-tocopherol for the stabilization of polyolefin-based thermoplastic polymers (WO-A-97/49758). Stabilization of polyolefins with phenolic antioxidants has also been described in R. Gachter, H.Mϋller; Handbook "Plastic Additives"("Kunststoffadditive"), 3. German Edition, Carl Hanser Publishers, Munich, Vienna 1990; pp 68.

Object of the instant invention are stabilizer compositions for thermoplastic polymers, especially for polyamides, comprising

a) at least one phenolic antioxidant selected from the compounds (I) to (V):

bis-[3,3-bis-(4'-hydroxy-3'-tert.butylphenyl)-butanoic acid]-glycolester (I),

4_l4^,,4"-[(2,4,6-trimethyl-1 ,3,5-benzenetriyl)tris(methylene)]-tris[2,6-bis(1 ,1 - dimethylethyl)phenol] (II),

1 ,3,5-triazine-2,4,6(1H,3H,5HHrione, 1 ,3,5-tris[[4-(1 ,1-dimethylethyl)-3- hydroxy-2,6-dirnethylphenyl]methyl] (III), phenol, 4,4',4"-(1-methyl-1-propanyl-3-ylidene)tris[2-(1 ,1-dimethylethyl)-5- methyl (IV), or

phenol, 2,6-bis[[3-(1 ,1-dimethylethyl)-2-hydroxy-5-methylphenyl]octahydro- 4,7-methano-1 H-indenyl]-4-methyl (V)

and

b) at least one phenolic antioxidant selected from the compounds (VI), (VII) or (VIII):

benzenepropanoic acid, 3-(1 ,1-dimethylethyl)-4-hydroxy-5-methyl-, 2,4,8, 10-tetraoxa-spiro[5.5]undecane-3,9-diyl-bis(2,2-dimethyl-2, 1 - ethanediyl) ester (VI),

tetrakismethylene(3,5-di-tert.butyl-4-hydroxyphenyl)-hydrocinnamate (VII) or

octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (VIII),

wherein the weight ratio of component a) to component b) is from 1:10 to 10:1 , preferably from 1 :2 to 2:1.

The compounds (I) to (VIII) are commercially available products of the following chemical structure:

Compound (I)

Compound (II)

Compound (III)

Compound (IV)

Compound (V)

Compound (VI)

Compound (VII)

Compound (VIII)

Special preference is given to a stabilizer composition, wherein component a) is compound (I), (II) or (III) or any mixture thereof. Especially preferred is compound (I).

Further suitable phenolic antioxidants of group a) are:

1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene; 2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl)phenol; 2,4-bisoctylmercapto-6-(3,5-di-tert- butyl-4-hydroxyanilino)-1,3,5-triazine; 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4- hydroxyanilino)-1,3,5-triazine; 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxy- phenoxy)-1 ,3,5-triazine; 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1 ,2,3-tri- azine; 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate; 1,3,5-tris(4-tert- butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate; 2,4,6-tris(3,5-di-tert-butyl-4- hydroxyphenylethyl)-1 ,3,5-triazine; 1 ,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenyl- propionyl)hexahydro-1 ,3,5-triazine; or 1 ,3,5-tris(3,5-dicyclohexyl-4-hydroxy- benzyl) isocyanurate.

All phenolic components are used in a range between 0.001 and 2.000% weight- percent, preferentially in concentrations between 0.020 and 0.200 weight-percent, related to the thermoplastic polymer to be stabilized, for the long term use especially in polyamide articles.

A further object of the instant invention therefore is a method of use of said stabilizer compositions for the stabilization of thermoplastic polymers, especially polyamides, in concentrations of 0.001 % to 2.000 %, preferably 0.020 % to 0.20 % by weight, based on the polymer.

Another object of the instant invention is a process of stabilizing thermoplastic polymers, especially polyamides, by incorporating 0.001 % to 2.000 %, preferably 0.020 % to 0.20 % of said stabilizer compositions by weight, based on the polymer, of said stabilizer compositions.

A further aspect of the invention are stabilizer compositions for thermoplastic polymers, especially for polyamides, comprising the abovementioned compositions of phenolic antioxidants in combination with sterically hindered phosph(on)ites of the general formulae

Phosphites: P-(OAr)₃

Phosphonites: P-(OAr)₃.„ Ar'_n (n =1 ,2; Ar = Ar' or Ar ≠ Ar' )

in which Ar and Ar" have the meaning of an aromatic rest which is preferably sub- stituted by branched alkyl rests.

An example for a phosphite is compound (IX). Compound (IX)

Compound (X) is an example for the class of phosphonites.

Compound (X)

All sterically hindered phosph(on)ites are used in a range between 0.001 and 2.000% weight-percent, preferably in concentrations between 0.020 and 0.200 weight-percent, related to the thermoplastic polymer to be stabilized, for the long term use especially in polyamide articles.

The ratio between the phenolic components and the sterically hindered phosph(on)ites to be used is between 10:1 and 1:10, preferentially between 4:1 and 1:4.

Surprisingly, the mixtures according to the invention also outperform single tailor-made sterically hindered phenolic antioxidants such as Irganox^® 1098 (Irganox is a Trademark of Ciba Specialities).

Irganox 1098

Preferred thermoplastic polymers to be stabilized according to the instant invention are the following ones:

Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 6/9, polyamide 6/12, polyamide 4/6, polyamide 12/12, polyamide 11 and polyamide 12, aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and iso-phthalic and/or terephthalic acid and with or without an elastomer as modifier, for example poly-2,4,4-trimethylhexa-methylene terephthalamide or poly-m-phenylene isophthalamide. Copolymers based on different polyamide types like polyamide 6/12, polyamide 6/66.

Block copolymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or polytetramethylene glycol. Also polyamides or copolyamides modified with EPDM, EVA, SBR, acrylate elastomers or ABS; and polyamides condensed during processing (RIM polyamide systems). Finally copolymers of polyamides and carboxypropyl silicones and polyamide/polyether block copolymers.

Blends of polyamides with all kinds of other polymers including polyolefins e.g. Nylex^® based on Multibase^® alloying technology. Other commercially important blends are those of polyamides and polyesters, often compatibilized by addition of ionomers, but also wool-polyamide blends. Further, blends of polyamides with viscose, polyurethanes (Spandex) and cotton. Finally, blends of acrylonitrile/butadiene/styrene copolymers and polyamide. Blend components of polyamides are also described in the following list of polymers which generally can be stabilized by compositions according to the invention.

1. Polymers of monoolefins and diolefins, for example polypropylene, polyiso- butylene, polybut-1-ene, poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for example of cyclopentene or norbomene; furthermore polyethylene (which optionally can be crosslinked); for example, high density polyethylene (HDPE), polyethylene of high density and high molar mass (HDPE-HMW), polyethylene of high density and ultrahigh molar mass (HDPE- UHMW), medium density polyethylene (HMDPE), low density polyethylene

(LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE).

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

a) free-radical polymerization (normally under high pressure and at elevated temperature)

b) catalytic polymerization using a catalyst that normally contains one or more metals of group IVb, Vb, Vlb or VIII of the Periodic Table. These metals usually have one or more ligands, such as oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either π- or σ-coordinated. These metal complexes may be in the free form or fixed on substrates, for example on activated magnesium chloride, titanium(lll) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerization medium. The catalysts can be active as such in the polymerization or further activators may be used, for example metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, the metals being elements of groups la, I la and/or Ilia of the Periodic Table. The activators may be modified, for example, with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC). 2. Mixtures of the polymers mentioned under 1 ), for example mixtures of polypropylene with polyisobutylene, polyethylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE) with one another.

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-1-ene copolymers, propylene-isobutylene copolymers, ethylene- but-1-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-norbomene; and mixtures of such copolymers with one another and with polymers mentioned under 1 ), for example polypropylene-ethylene- propylene copolymers, LDPE-ethylene-vinyl acetate copolymers, LDPE-ethylene- acrylic acid copolymers, LLDPE-ethylene-vinyl acetate copolymers, LLDPE- ethylene-acrylic acid copolymers and alternating or random polyalkylene-carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides.

4. Hydrocarbon resins (for example C₅-C₉) including hydrogenated modifications thereof (e.g. tackifier resins) and mixtures of polyalkylenes and starch.

5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene).

6. Copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives, for example styrene-butadiene, styrene-acrylonitrile, styrene-alkyl methacrylate, styrene-butadiene-alkyl acrylate, styrene-butadiene-alkyl methacrylate, styrene- maleic anhydride, styrene-acrylonitrile-methacrylate; mixtures of high impact strength of styrene copolymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene-propylene-diene terpolymer; and block copoly- mers of styrene, such as styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butylene-styrene or styrene-ethylene/propylene-styrene.

7. Graft copolymers of styrene or α-methylstyrene, for example styrene on poly- butadiene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers, styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on polybutadiene; styrene and alkyl acrylates or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene-propylene-diene terpolymers, styrene and acrylonitrile on poly- alkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate- butadiene copolymers, as well as mixtures thereof with the copolymers mentioned under 6), for example the copolymer mixtures known as ABS, MBS, ASA or AES polymers.

8. Halogen-containing polymers, such as polychloroprene, chlorinated rubber, chlorinated and brominated copolymer of isobutylene-isoprene (halobutyl ruuber), chlorinated or sulfochlorinated polyethylene, copolymers of ethylene and chlorinated ethylene, epichlorohydrin homo- and copolymers, especially polymers of halogen-containing vinyl compounds, for example polyvinyl chloride, polyvinyl- idene chloride, polyvinyl fluoride, polyvinylidene fluoride; as well as copolymers thereof such as vinyl chloride-vinylidene chloride, vinyl chloride-vinyl acetate or vinylidene chloride-vinyl acetate.

9. Polymers derived from α,β-unsaturated acids and derivatives thereof, such as polyacrylates and polymethacrylates, polyacrylonitriles, polyacrylamides and polymethyl methacrylates impact-modified with butyl acrylate.

10. Copolymers of the monomers mentioned under 9) with each other or with other unsaturated monomers, for example acrylonitrile-butadiene copolymers, acrylo- nitrile-alkyl acrylate copolymers, acrylonitrile-alkoxyalkyl acrylate copolymers, acrylonitrile-vinyl halide copolymers or acrylonitrile-alkyl methacrylate-butadiene terpolymers. 11. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals thereof, such as polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as well as their copolymers with olefins mentioned in section 1.

12. Homopolymers and copolymers of cyclic ethers, such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers.

13. Polyacetals such as polyoxymethylene and those polyoxymethylenes which contain comonomers, for example ethylene oxide; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS.

14. Polyphenylene oxides and sulfides.

15. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters and poly- butadienes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof.

16. Polyureas, polyimides, polyamide-imides, polyether imides, polyester amides, polyhydantoins and polybenzimidazoles.

17. Polyesters derived from dicarboxylic acids and dialcohols and/or from hydroxy- carboxylic acids or the corresponding lactones, such as polyethylene tere- phthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane tere- phthalate, polyhydroxybenzoates, as well as block polyether esters derived from hydroxyl-terminated polyethers; and also polyesters modified with polycarbonates or MBS.

18. Polycarbonates and polyester carbonates.

19. Polysulfones, polyether sulfones and polyether ketones. 20. Crosslinked polymers derived from aldehydes on the one hand and phenols, urea or melamine on the other hand, such as phenol/formaldehyde resins, urea/- formaldehyde resins and melamine/formaldehyde resins.

21. Drying and non-drying alkyd resins.

22. Unsaturated polyester resins derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols and vinyl compounds as crosslinking agents, and also halogen-containing modifications thereof of low flammability.

23. Crosslinkable acrylic resins derived from substituted acrylates, for example from epoxy acrylates, urethane acrylates or polyester acrylates.

24. Alkyd resins, polyester resins and acrylic resins crosslinked with melamine resins, urea resins, isocyanates, isocyanurates, polyisocyanates or epoxy resins.

25. Crosslinked epoxy resins derived from aliphatic, cycloaliphatic, heterocyclic or aromatic glycidyl compounds, examples being products of bisphenol A diglycidyl ethers, bisphenol F diglycidyl ethers, which are crosslinked by means of customary hardeners, such as anhydrides or amines, for example, with or without accelerators.

26. Natural polymers such as cellulose, natural rubber, gelatin and derivatives there- of which have been chemically modified in a polymer-homologous manner, for example cellulose acetates, cellulose propionates and cellulose butyrates, or the cellulose ethers such as methyl cellulose; as well as rosins and derivatives.

27. Natural and synthetic organic substances which constitute pure monomeric compounds or mixtures thereof, examples being mineral oils, animal or vegetable fats, oils and waxes, or oils, waxes and fats based on synthetic esters (e.g. phthalates, adipates, phosphates or trimellitates), and also blends of synthetic esters with mineral oils in any desired proportion by weight, as are employed, for example, as spin finishes, and aqueous emulsions thereof. 28. Aqueous emulsions of natural or synthetic rubbers, such as natural rubber latex or latices of carboxylated styrene-butadiene copolymers.

The stabilizer compositions of the instant invention or the thermoplastic polymers to be stabilized may, if desired, also comprise further additives, examples being antioxidants, light stabilizers, metal deactivators, antistatic agents, flame retardants, lubricants, nucleating agents, acid scavengers (basic costabilizers), pigments and fillers. Examples of suitable additives which can additionally be employed in combination are compounds as set out below:

1. Antioxidants

1.1 Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6- dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α-methyl- cyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclo- hexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, linear or sidechain- branched nonylphenols, such as 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1- methylundec-1 '-yl)-phenol, 2,4-dimethyl-6-(1 '-methylheptadec-1 '-yl)-phenol, 2,4- dimethyl-6-(1'-methyltridec-1'-yl)phenol and mixtures thereof.

1.2 Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4- dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di- dodecylthiomethyl-4-nonylphenol .

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

1.4 Hydroxylated thiodiphenyl ethers, for example 2,2'-thiobis(6-tert-butyl-4-methyl- phenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-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. 1.5 Alkylidenebisphenols, for example 2,2'-methylenebis(6-tert-butyl-4-methyl- phenol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-methylenebis[4- methyl-6-(α-methylcyclohexyl)phenol], 2,2'-methylenebis(4-methyl-6-cyclohexyl- phenol), 2,2'-methylenebis(6-nonyl-4-methylphenol), 2,2'-methylenebis(4,6-di- tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(6- tert-butyl-4-isobutylphenol), 2,2'-methylenebis[6-(α-methylbenzyl)-4-nonylphenol], 2,2'-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol], 4,4'-methylenebis(2,6- di-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-2-methylphenol), 1 ,1-bis(5-tert- butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxy- benzyl)-4-methylphenol, 1 ,1 ,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,

1 ,1 -bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, bis- (3-tert-butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene, bis[2-(3'-tert-butyl-2'- hydroxy-5'-methylbenzyl)-6-tert-butyl-4-methylphenyl] terephthalate, 1 ,1-bis(3,5- dimethyl-2-hydroxyphenyl)butane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)- propane, 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercapto- butane, 1 ,1 ,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane, ethylene glycol bis[3,3-bis(3'-tert-butyl-4'-hydroxyphenyl)butyrate].

1.6 O-, N- and S-benzyl compounds, for example 3,5,3',5'-tetra-tert-butyl-4,4'-di- hydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bis(4-tert-butyl-3-hydroxy-2,6-di- methylbenzyl) dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, tridecyl 4-hydroxy-3,5- di-tert-butylbenzylmercaptoacetate.

1.7 Hydroxybenzylated malonates, for example dioctadecyl 2,2-bis(3,5-di-tert-butyl-2- hydroxybenzyl)malonate, dioctadecyl 2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)- malonate, didodecyl mercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)- malonate, di-[4-(1 ,1 ,3,3-tetramethylbutyl)phenyl] 2,2-bis(3,5-di-tert-butyl-4- hydroxybenzyl)malonate.

1.8 Benzylphosphonates, for example dimethyl 2,5-di-tert-butyl-4-hydroxybenzyl- phosphonate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 5-tert-butyl-4-hydroxy- 3-methylbenzylphosphonate, the Ca salt of the monoethyl ester of 3,5-di-tert- butyl-4-hydroxybenzylphosphonic acid . 1.9 Acylaminophenols, for example 4-hydroxylauranilide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate.

1.10 Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or poly- hydric alcohols, e.g. with methanol, ethanol, n-octanol, isooctanol, 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)oxalamide, 3-thiaun- decanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxy- methyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.11 Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, isooctanol, octa- decanol, 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'-bisfhydroxyethy oxalamide, 3- thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4- hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.12 Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, isooctanol, 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)oxalamide, 3-thiaun- decanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxy- methyl-1 -phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.13 Esters of 3,5-di-tert-butyl-4-hydroxyphenylacetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, isooctanol, 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)oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1- phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.14 Esters of 3,3-bis(3'tert-butyl-4'-hydroxyphenyl)butyric acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, isooctanol, octadecanol, 1 ,6-hexanediol, 1 ,9-nonanediol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) iso- cyanurate, N,N'-bis-(hydroxyethyl)oxalamide, 3-thia-undecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha- 2,6,7-trioxabicyclo[2.2.2]octane.

1.15 Amides of β-(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-di-tert-butyl-4- hydroxyphenylpropionyl)hydrazine.

1.16 Tocopherol, such as α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (vitamin E).

1.17 Ascorbic acid (vitamin C).

1.18 Amine antioxidants, for example N,N'-diisopropyl-p-phenylenediamine, N.N'di- sec-butyl-p-phenylenediamine, 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'-di(naphthyl-2-)-p-phenylenediamine, N-isopropyl-N'- phenyl-p-phenylenediamine, N-(1 ,3-dimethylbutyl)-N'-phenyl-p-phenylenedi- amine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'- phenyl-p-phenylenediamine, 4-(-toluenesulfonamido)diphenylamine, N,N'-di- methyl-N.N'-di-sec-butyl-p-phenylenediamine, diphenylamine, N-allyldiphenyl- amine, 4-isopropoxydiphenylamine, N-phenyl-1-naphthylamine, N-(4-tert-octyl- phenyl)-1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, e.g. p.p'-di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol,

4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octadecanoylamino- phenol, di(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4-dimethylaminomethyl- phenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N,N,N',N'- tetramethyl-4 ,4 -diaminodiphenylmethane , 1 ,2-di-[(2-methylphenyl )amino]ethane , 1 ,2-di-(phenylamino)propane, (o-tolyl)biguanide, di[4-(1',3'-dimethylbutyl)-phenyl]- amine, tert-octylated N-phenyl-1-naphthylamine, mixture of mono- and di- alkylated tert-butyl/tert-octyldiphenylamines, mixture of mono- and dialkylated nonyldiphenylamines, mixture of mono- and dialkylated dodecyldiphenylamines, mixture of mono- and dialkylated isopropyl/isohexyl-diphenylamines, mixture of mono- and dialkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1 ,4- benzothiazine, phenothiazine, mixture of mono- and dialkylated tert-butyl/tert- octyl-phenothiazines, mixture of mono- and dialkylated tert-octylphenothiazines, N-allylphenothiazine, N,N,N',N'-tetraphenyl-1 ,4-diaminobut-2-ene, N,N-bis- (2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine, bis(2,2,6,6-tetramethyl- piperidin-4-yl) sebacate, 2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethyl- piperidin-4-ol.

2. UV absorbers and light stabilizers

2.1 2-(2'-Hydroxyphenyl)benzotriazoles, 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 ,3,3-tetramethylbutyl)- phenyljbenzotriazole, 2-(3',5'-di-tert-butyl-2^,-hydroxyphenyl)-5-chlorobenzo- triazole, 2-(3^,-tert-butyl-2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, 2-(3'- sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxy- phenyl)benzotriazole, 2-(3',5^,-di-tert-amyl-2^,-hydroxyphenyl)benzotriazole, 2-

(3',5'-bis(α,α-dimethylbenzyl)-2^,-hydroxyphenyl)benzotriazole, a mixture of 2-(3'- tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chlorobenzotriazole, 2- (3'-tert-butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'-hydroxyphenyl)-5-chloro- benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5^,-(2-methoxycarbonylethyl)phenyl)-5- chlorobenzotriazole, 2-(3'-tert-butyl-2^,-hydroxy-5^,-(2-methoxycarbonylethyl)- phenyl)benzotriazole, 2-(3'-tert-butyl-2^,-hydroxy-5'-(2-octyloxycarbonylethyl)- phenyl)benzotriazole, 2-(3'-tert-butyl-5^,-[2-(2-ethylhexyloxy)carbonylethyl]-2'- hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzo- triazole, and 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenyl- benzotriazole, 2,2^,-methylenebis[4-(1 _l1,3,3-tetramethylbutyl)-6-benzotriazol-2- ylphenol]; the transesterification product of 2-[3'-tert.-butyl-5'-(2-methoxycarbonyl- ethyl)-2'-hydroxyphenyl]benzotriazole with polyethylene glycol 300; [R-CH₂CH₂- COO(CH₂)₃]₂ where R = S'-tert-butyW-hydroxy-S'^H-benzotriazol^-ylphenyl. 2.2 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4-octoxy, 4- decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2^,,4'-trihydroxy and 2'-hydroxy-4,4'-di- methoxy derivative.

2.3 Esters of substituted or unsubstituted benzoic acids, for example 4-tert-butyl- phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoylresorcinol, bis(4-tert-butylbenzoyl)resorcinol, benzoylresorcinol, 2,4-di-tert-butylphenyl 3,5- di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate.

2.4 Acrylates, for example ethyl α-cyano-β,β-diphenylacrylate or isooctyl α-cyano- β,β-diphenylacrylate, methyl α-carbomethoxycinnamate, methyl α-cyano-β- methyl-p-methoxycinnamate or butyl α-cyano-β-methyl-p-methoxycinnamate, methyl α-carbomethoxy-p-methoxycinnamate and N-(β-carbomethoxy-β-cyano- vinyl)-2-methylindoline.

2.5 Benzylidene-malonates like [(4-methoxyphenyl)methylene]-propanedioic acid dimethylester and benzylidene-bis-malonates like tetra-alkyl-2,2'-(1,4-phenylene- dimethylidene)-bismalonates.

2.6 Nickel compounds, for example nickel complexes of 2,2'-thio-bis-[4-(1 , 1 ,3,3- tetramethylbutyl)phenol], such as the 1 :1 or 1 :2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldi- ethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters, such as of the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzyl- phosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methyl- phenyl undecyl ketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxy- pyrazole, with or without additional ligands.

2.7 Sterically hindered amines, for example bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(2,2,6,6-tetramethylpiperidin-4-yl) glutarate, bis(2,2,6,6-tetramethyl- piperidin-4-yl) succinate, bis(1 ,2,2,6,6-pentamethylpiperidin-4-yl) sebacate, bis- (1 ,2,2,6,6-pentamethylpiperidin-4-yl) glutarate, 2,2,6,6-tetramethylpiperidyl behenate, 1 ,2,2,6,6-pentamethylpiperidyl behenate, the condensate of 1- hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)hexamethylendiamine and 4-tert-octylamino-2,6-dichloro-1 ,3,5-s-triazine, tris-(2,2,6,6-tetramethyl-4- piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1 ,2,3,4-butan- tetraoate, 1 , 1 '-(1 ,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone), 4-benzoyl- 2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4- stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-1 ,2,2,6,6-pentamethyl- piperidine, 4-stearoyloxy-1 ,2,2,6,6-pentamethylpiperidine, bis(1 ,2,2,6, 6-penta- methylpiperidyl) 2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, bis- (1 ,2,2,6,6-pentamethylpiperidyl) 2-n-butyl-2-(4-hydroxy-3,5-di-tert-butylbenzyl)- malonate, 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5] decane-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate, bis-(1-octyloxy-2,2,6,6- tetramethylpiperidyl) succinate, the condensate of N,N'-bis(2,2,6,6-tetramethyl-4- piperidyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1 ,3,5-triazine, the condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1 ,3,5-triazine, the condensate of 2-chloro-

4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis-(3- aminopropylamino)ethane, the condensate of 2-chloro-4,6-di-(4-methoxypropyl- amino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis-(3-aminopropyl- amino)ethane, the condensate of 2-chloro-4,6-di-(4-methoxypropylamino- 1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis-(3-aminopropylamino)- ethane, the condensate of 2-chloro-4,6-di-(4-n-butylamino-1 ,2,2,6,6-pentamethyl- piperidyl)-1 ,3,5-triazine and 1 ,2-bis-(3-aminopropylamino)-ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5- triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, 1 ,2-bis-(3- aminopropylamino)ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino- 1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetriamine, triethylenetetramin, hexamethylenediamine, 1 ,2-bis(3-aminopropylamino)ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5-triazine and 4- tert-octylamino-2,6-dichloro-1 ,3,5-s-triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, 1 ,2-bis(3-aminopropylamino)ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino-1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine and 4-tert-octylamino-2,6-dichloro-1 ,3,5-s-triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, 1 ,2-bis-(3-aminopropyl-amino)ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5-triazine and 4-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-2,6-dichloro-1 ,3,5-s-triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetri- amine, triethylenetetramine, hexamethylenediamine, 1 ,2-bis-(3-aminopropyl- amino)ethane, reaction products of 2-chloro-4,6-di-(4-n-butylamino-1 , 2,2,6,6- pentamethylpiperidyl)-1 ,3,5-triazine and 4-(4-n-butylamino-2,2,6,6-tetramethyl- piperidyl)-2,6-dichloro-1 ,3,5-s-triazine with mono- or polyfunctional amines, where between one and all the active hydrogen atoms on the amine are replaced, such as with ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, 1 ,2-bis-(3-aminopropylamino)ethane, the condensate of 1 ,2- bis(3-aminopropylamino)ethane and 2,4,6-trichloro-1 ,3,5-triazine and also 4- butylamino-2,2,6,6-tetramethylpiperidine, N-(2,2,6,6-tetramethyl-4-piperidyl)-n- dodecylsuccinimide, N-(1 ,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimide, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decane-2,4-dione, oligomerized 2,2,4,4-tetramethyl-20-(oxiranylmethyl)-7-oxa-3,20-diaza-dispiro- [5.1.11.2]heneicosan-21-one, oligomerized 1 ,2,2,4,4-pentamethyl-20-(oxiranyl- methyl)-7-oxa-3,20-diazadispiro[5.1.11.2]heneicosan-21-one, oligomerized 1- acetyl-2,2,4,4-tetramethyl-20-(oxiranylmethyl)-7-oxa-3,20-diaza-dispiro[5.1.11.2]- heneicosan-21-one, 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5- dione, 3-dodecyl-1 -(1 ,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, 2,2,4,4-tetramethyl-7-oxa-3,20-diazadispiro-[5.1.11.2]heneicosan-21-one, 2,2,4,4-tetramethyl-7-oxa-21-oxo-3,20-diazadispiro-[5.1.11.2]heneicosane-3- propanoic acid dodecyl ester, 2,2,4,4-tetramethyl-7-oxa-21-oxo-3,20-diaza- dispiro-[5.1.11.2]heneicosane-3-propanoic acid tetradecyl ester, 2,2,3,4,4-penta- methyl-7-oxa-3,20-diazadispiro-[5.1.11.2]heneicosan-21-one, 2,2,3,4,4-penta- methyl-7-oxa-21-oxo-3,20-diaza-dispiro-[5.1.1 1.2]heneicosane-3-propanoic acid dodecyl ester, 2,2,3,4,4-pentamethyl-7-oxa-21-oxo-3,20-diazadispiro-[5.1.11.2]- heneicosane-3-propanoic acid tetradecyl ester, 3-acetyl-2,2,4,4-tetramethyl-7- oxa-3,20-diazadispiro-[5.1.11.2]heneicosane-21-one, 3-acetyl-2,2,4,4-tetra- methyl-7-oxa-21-oxo-3,20-diaza-dispiro-[5.1.1 1.2]heneicosane-3-propanoic acid dodecyl ester, 3-acetyl-2,2,4,4-tetramethyl-7-oxa-21 -oxo-3,20-diazadispiro- [5.1.1 1.2]heneicosane-3-propanoic acid tetradecyl ester, 1 ,1',3,3',5,5'-hexahydro- 2,2\4,4\6,6^,-hexaaza-2,2\6,6'-bismethano-7,8-dioxo-4,4'-bis(1 ,2,2,6,6-penta- methyl-4-piperidyl)biphenyl, poly-N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-1 ,8- diazadecylene, adduct of 2,2,6,6-tetramethyl-4-allyloxypiperidine and polymethyl- hydridosiloxane (molar mass up to 4000), adduct of 1 ,2,2,6,6-pentamethyl-4- allyloxypiperidine and polymethylhydridosiloxane (molar mass up to 4000), N,N'- diformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine, N,N'- diformyl-N,N'-bis(1 ,2,2,6,6-pentamethyl-4-piperidinyl)hexamethylenediamine, 5,1 1-bis-(2,2,6,6-tetramethyl-4-piperidinyl)-3,5,7,9,11 , 13-hexaazatetra-cyclo-

[7.4.0.0²'⁷.1^{3 13}]tetradecane-8,14-dione, 5,11-bis(1 , 2,2,6, 6-pentamethyl-4- piperidinyl)-3,5,7,9,11 ,13-hexaazatetra-cyclo[7.4.0.0²'⁷.1³'¹³]tetradecane-8,14- dione, [(4-methoxyphenyl)methylene]-propanedioic acid bis(2,2,6,6-tetramethyl- 4-piperidinyl) ester, [(4-methoxyphenyl)-methylene]propanedioic acid bis- (1 ,2,2,6,6-pentamethyl-4-piperidinyl) ester, 2,4,6-tris(N-cyclohexyl-N-[2-

(3,3,4,5,5-pentamethylpiperazinon-1-yl)ethyl]amino)-1 ,3,5-triazine, copolymer of styrene with methylstyrene and maleic anhydride reacted with 4-amino-2, 2,6,6- tetramethylpiperidine and octadecylamine, copolymer of styrene with α-methyl- styrene and maleic anhydride reacted with 4-amino-1 ,2,2,6,6-pentamethyl- piperidine and octadecylamine, polycarbonate with 2,2'-[(2,2,6,6-tetramethyl-4- piperidinyl)imino]bis[ethanol] as diol component, polycarbonate comprising 2,2'- (1 ,2,2,6,6-pentamethyl-4-piperidinyl)imino]bis[ethanol] as diol component, copolymer of maleic anhydride and an α-olefin up to C₃₀ reacted with 4-amino- 2,2,6,6-tetramethylpiperidine, copolymer of maleic anhydride and an α-olefin up to C₃₀ reacted with 1-acetyl-4-amino-2,2,6,6-tetramethylpiperidine, copolymer of maleic anhydride and an α-olefin up to C₃₀ reacted with 4-amino-1 , 2,2,6,6- pentamethylpiperidine, and also the N-alkyl- and N-aryl-oxy derivatives of the abovementioned compounds with free NH groups on the piperidine, especially α-methylbenzyloxy and alkyloxy from Ci to C₁₈.

2.8 Oxalamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyanilide, 2,2'-di- octyloxy-5,5'-di-tert-butyloxanilide, 2,2'-didodecyloxy-5,5^,-di-tert-butyloxanilide, 2- ethoxy-2'-ethyloxanilide, N,N'-bis(3-dimethylaminopropyl)-oxalamide, 2-ethoxy-5- tert-butyl-2'-ethyloxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butyl- oxanilide and mixtures of o- and p-methoxy-disubstituted and of o- and p-ethoxy- disubstituted oxanilides. 2.9 2-(2-Hydroxyphenyl)-1 ,3,5-triazines, for example 2,4,6-tris(2-hydroxy-4-octyloxy- phenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4\6-bis(2',4-dimethyl- phenyl)-1 ,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(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(4-methylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4- dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-[2-hydroxy-4-(2- hydroxy-3-butyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethyl- phenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethyl- phenyl)-1 ,3,5-triazine, 2-[4-dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxy- phenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3- dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-(2- hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1 ,3,5-triazine, 2-(2-hydroxy-4-methoxy- phenyl)-4,6-diphenyl-1 ,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxy- propoxy)phenyl]-1 ,3,5-triazine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6- phenyl-1 ,3,5-triazine.

3. Metal deactivators, for example, N.N'-diphenyloxalamide, N-salicylal-N'-salicyloyl- hydrazine, N,N'-bis(salicyloyl)hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxy- phenylpropionyl)hydrazine, 3-salicyloylamino-1 ,2,4-triazole, bis(benzylidene)- oxalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenyl- hydrazide, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyloyl)oxalyl di- hydrazide, N,N^,-bis(salicyloyl)thiopropionyl 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-di- tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert- butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bisisodecyloxy pentaerythritol diphosphite, bis(2,4-di- tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri-tert-butyl- phenyl) pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di- tert-butylphenyl) 4,4'-biphenylenediphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert- butyl-12H-dibenzo[d,g]-1 ,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl- 12-methyl-dibenzo[d,g]-1 ,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methyl- phenyl) methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, tris(2-tert-butyl-4-thio(2'-methyl-4'-hydroxy-5^,-tert-butyl)phenyl-5-methyl) phenyl phosphite, 2,2',2"-nitrilo[triethyl tris(3,3^,,5,5'-tetra-tert-butyl-1 , 1 '-biphenyl-2,2'-diyl) phosphite], bis[2-methyl-4,6-bis(1,1-dimethylethyl)phenol]phosphorous acid ethyl ester.

5. Hydroxylamines, examples being N,N-dibenzylhydroxylamine, N,N-diethyl- hydroxylamine, N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-di- tetradecylhydroxylamine, N,N-dihexadecylhydroxylamine, N,N-dioctadecyl- hydroxylamine, N-hexadecyl-N-octadecylhydroxylamine, N-heptadecyl-N-octa- decylhydroxylamine, N,N-dialkylhydroxylamines prepared from hydrogenated tallow fatty amine.

6. Nitrones, examples being N-benzyl alpha-phenyl nitrone, N-ethyl alpha-methyl nitrone, N-octyl alpha-heptyl nitrone, N-lauryl alpha-undecyl nitrone, N-tetradecyl alpha-tridecyl nitrone, N-hexadecyl alpha-pentadecyl nitrone, N-octadecyl alpha- heptadecyl nitrone, N-hexadecyl alpha-heptadecyl nitrone, N-octadecyl alpha- pentadecyl nitrone, N-heptadecyl alpha-heptadecyl nitrone, N-octadecyl alpha- hexadecyl nitrone, nitrones derived from N,N-dialkylhydroxylamines prepared from hydrogenated tallow fatty amines.

7. Zeolites and hydrotalcites, such as ^®DHT 4A. Hydrotalcites of this kind can be described by the formula

[(M ⁺)₁._x (M³⁺)_x (OH)₂ (Aⁿ-)_x/n yH₂O],

where

(M²⁺) is Mg, Ca, Sr, Ba, Zn, Pb, Sn, Ni (M³⁺) is Al, B, Bi

A" is an anion of valence n n is an integer from 1 - 4 x is a value between 0 and 0.5 y is a value between 0 and 2 A is OH^", Cr, Br^", I^", CIO₄-, CH₃COO-, C₆H₅COO-, CO₃ ^2', SO₄ ^2", (OOC-COO)^2", (CHOHCOO)₂ ²-, (CHOH)₄CH₂OHCOO-, C₂H₄(COO)₂ ²-, (CH₂COO)₂ ^2", CH₃CHOHCOO-, SiO₃ ²-, SiθΛ Fe(CN)₆ ^3', Fe(CN)₆ ⁴\ BO₃ ^3", PO₃ ^3", HPO₄ ²\

Preference is given to employing hydrotalcites in which (M²⁺) is (Ca²⁺), (Mg²⁺) or a mixture of (Mg²⁺) and (Zn²⁺); (A^n") is CO₃ ^2", BO₃ ^3', PO₃ ^3"; x has a value from 0 to 0.5 and y has a value from 0 to 2. It is also possible to employ hydrotalcites that can be described with the formula

[(M²⁺)_x (AI³⁺)₂ (OH)_2x+6nz (A^n")₂ yH₂O].

Here, (M²⁺) is Mg²⁺, Zn²⁺, but more preferably Mg²⁺. (A^n") is an anion, in particular from the group consisting of CO₃ ^2", (OOC-COO)^2', OH^" and S^2", where n describes the valency of the ion. y is a positive number, more preferably between 0 and 5, especially between 0.5 and 5. x and z have positive values, which in the case of x are preferably between 2 and 6 and in the case of z should be less than 2. The hydrotalcites of the following formulae are to be regarded with particular preference:

AI₂O₃ x 6MgO x CO₂ x 12H₂O,

Mg_{4 5}AI₂(OH)₁₃ x CO₃ x 3.5H₂O,

4MgO x AI₂O₃ x CO₂ x 9H₂O,

4MgO x AI₂O₃ x CO₂ x 6H₂O,

ZnO x 3MgO x AI₂O₃ x CO₂ x 8-9H₂O, ZnO x 3MgO x AI₂O₃ x CO₂ x 5-6H₂O,

Mg_{4 5}AI₂(OH)₁₃ x CO₃ .

Hydrotalcites are employed in the polymer preferably in a concentration of from 0.01 to 5 % by weight, in particular from 0.2 to 3 % by weight, based on the overall polymer formulation.

8. Thiosynergists, examples being dilauryl thiodipropionate and distearyl thiodipropionate.

9. Peroxide scavengers, examples being esters of β-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl ester, mecaptobenzimidazole, the zinc salt of 2-mercaptobenzimidazole, zinc alkyldithiocarbamates, zinc dibutyldi- thiocarbamate, dioctadecyl monosulfide, dioctadecyl disulfide, pentaerythritol tetrakis(β-dodecylmercapto)propionate.

10. Polyamide stabilizers, examples being copper salts in combination with iodides and/or phosphorus compounds and salts of divalent manganese.

11. Basic costabilizers, examples being melamin, polyvinylpyrrolidone, dicyandi- amide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, poly- amines, polyurethanes, alkali metal and alkaline earth metal salts of higher fatty acids, for example Ca stearate, Zn stearate, Mg behenate, Mg stearate, Na ricinoleate, K palmitate, antimony pyrocatecholate or tin pyrocatecholate, alkali metal and alkaline earth metal salts and also the zinc salt, the calcium salt or the aluminum salt of lactic acid.

12. Nucleating agents, such as inorganic substances, examples being talc, metal oxides, such as titanium oxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals, organic compounds, such as mono- or polycarboxylic acids and also their salts, examples being 4-tert-butylbenzoic acid, adipic acid; diphenylacetic acid; sodium succinate or sodium benzoate; acetals of aromatic aldehydes and polyfunctional alcohols such as sorbitol, for example, such as 1,3-2,4-di(benzylidene)-D-sorbitol, 1,3-2,4-di(4-tolylidene)-D- sorbitol, 1 ,3-2,4-di(4-ethylbenzylidene)-D-sorbitol, polymeric compounds, such as ionic copolymers (ionomers), for example.

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

14. Other additives, examples being plasticizers, lubricants, emulsifiers, pigments, rheological additives, catalysts, leveling assistants, optical brighteners, flame- proofing agents, antistatics, blowing agents.

15. Benzofuranones and indolines, as described for example in US-4325863, US- 4338244, US-5175312; US-5216052; US-5252643, DE-A-4316611, DE-A- 4316622, DE-A-4316876, EP-A-0589839 or EP-A-0591102, or 3-[4-(2-acetoxy- ethoxy)phenyl]-5,7-di-tert-butylbenzofuran-2-one, 5,7-di-tert-butyl-3-[4-(2- stearoyloxyethoxy)phenyl]-benzofuranon-2-one, 3,3'-bis[5,7-di-tert-butyl-3-(4-[2- hydroxyethoxy]phenyl)-benzofuran-2-one, 5,7-di-tert-butyl-3-(4-ethoxyphenyl)- benzofuran-2-one, 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butylbenzofuran-

2-one, 3-(3,5-diethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butylbenzofuran-2-one.

If the instant stabilizer compositions are employed in articles made of thermoplastic polymers, especially of polyamides, those articles show superior long term performance as measured by standard test methods such as yellowness index (YI). Hereby the polyamide resin can consist of thick sections or thin layers and therefore can be applied also as coated or laminated layer on metal articles such as steel-pipes or sea-cables.

The instant stabilizer systems used to stabilize all kinds of articles prepared from thermoplastic polymers are able to resist to an early consumption by migration out of the polymer resin. This behavior improves clearly the long term stability of the referred articles.

The technically important parameter of the yellowness index (YI) used to forecast the service life of plastic materials has been measured in polyamide articles which have been stabilized with binary mixtures of sterically hindered phenols. The measured Yl- values are clearly superior to those measured in samples where only one sterically hindered phenol was incorporated. These results stand for an improvement of the state-of-the art.

The following examples illustrate the invention. In the following tables "part" or "%" mean "part by weight" or "% by weight".

EXAMPLE

Polyamide-6 (PA-6), type Frianyl B63E (producer Frisetta) has been used for processing and long-term heat aging. 100 parts of this polymer have been mixed with 0.5 parts of the corresponding sterically hindered phenol or composition of phenols. Alternative mixtures have been prepared using 100 parts of the given PA-6 together with each 0.25 parts of a sterically hindered phenol respectively the 1 :1 mixture by weight of a phenol of type a) and of type b) e.g. composition A (see table 1 ) and 0.25 parts of Hostanox^® PAR 24 (tris-(2,4-di-tert.butylphenyl)-phosphite = Compound IX) . Hostanox is a Trademark of Clariant. Table 1 reflects the composition of the individually used formulations.

TABLE 1

Stabilizers used for processing of polyamide-6

virgin

0,500 % Hostanox^® O 3 = Compound I 0,500 % Hostanox^® O 310 = Composition A ¹⁾ 0,500 % Hostanox^® O 10 = Compound VII 0,500 % Irganox^® 1098 = State of the art 0,250 % Hostanox^® O 3 + 0,250 % Hostanox^® PAR 24

0,250 % Hostanox^® O 310 + 0,250 % Hostanox^® PAR 24 ¹⁾ 0,250 % Hostanox^® O 10 + 0,250 % Hostanox^® PAR 24 0,250 % Irganox^® 1098 + 0,250 % Hostanox^® PAR 24 ¹⁾ mixture according to the invention

Composition A is a mixture of 1 part Compound I and 1 part of Compound VII.

Pre-extrusion was carried out on a single screw extruder type T30 (producer Collin) (IJD =30, screw-diameter: 30 mm and die-diameter: 2 mm), at T=285°C and 50 rpm. Afterwards PA-6-plaques (100x100x1 mm) were processed at a temperature of T = 260°C by means of an injection molding machine (producer Arburg).

Long term heat stability tests were carried out on injection molded plaques both at 120°C and at 150°C. PA6-samples were exposed in ventilated ovens. Yellowness Index (YI) and L*a*b* were measured using a Minolta 3500d spectrocolorimeter according to DIN 6167 for YI and CIE 1976 for L*a*b*. As a result of those long term heat aging experiments carried out at T=120°C it can be stated that

the pure polymer shows a pronounced yellowing already after 20 hours exposure measured by the parameter b*. formulations based on phenolic antioxidants alone (Hostanox^® O 3, O 10 and Irganox^® 1098) all show a significant yellowing (b*>2) already after 50 hours.

Hostanox^® O 310 outperforms the above mentioned single sterically hindered phenols. Furthermore all formulations based on combinations of the phosphite-based processing stabilizer / phenolic antioxidant show much better color retention (lower b^*). Particularly the combinations Hostanox^® O3/Hostanox^® PAR 24 (1/1) and Hostanox^® O310 / Hostanox^® PAR 24 (1/1) show surprisingly better performance as compared to the established combination Irganox^® 1098 / Hostanox^® PAR24 (1/1) which reflects the state of the art.

Table 2 exhibits the results after certain periods of heat storage at T=120°C. The lowest (negartive) numbers reflect the best performance.

TABLE 2

Long term heat aging of PA-6 formulations tested at T= 120°C; influence of storage time on the color-parameter b^*

Similarly long term heat stability of the given PA-6 and the above described stabilizer formulations was tested at an oven temperature of T=150°C. The results are presented in table 3. The pure polymer and in a lower extent all the formulations based on phenolic antioxidant alone show a pronounced yellowing (b^* >8) after 20h of oven exposure. The best performance is achieved by Hostanox O 310.

All the formulations based on combinations processing stabilizer / phenolic antioxidant show clearly better color retention (lower b^*, representing a lower value in the yellow- blue dimension). Particularly the combinations Hostanox^® O3/Hostanox^® PAR 24 (1/1 ) and Hostanox^® O310 / Hostanox^® PAR 24 (1/1 ) outperform surprisingly the established combination Irganox^® 1098 / Hostanox^® PAR 24 (1/1) which means a distinct improvement of the state of the art.

TABLE 3

Long term heat aging of PA6 formulations tested at T= 150°C; influence of storage time on the color-parameter b*

mixture accor ng to t e nvent on

The experimental data clearly show the surprisingly superior stabilizing properties of the instant composition compared to the prior art.

Claims

1. A stabilizer composition for thermoplastic polymers comprising

a) at least one phenolic antioxidant selected from the compounds (I) to (V)

bis-[3,3-bis-(4'-hydroxy-3'-tert.butyl-phenyl)-butanoic acid]-glycolester (l),

4,4',4"-[(2,4,6-trimethyl-1 ,3,5-benzenetriyl)tris(methylene)]-tris[2,6- bis(1 ,1-dimethylethyl)phenol] (ll),

1 ,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[[4-(1,1-dimethylethyl)-3- hydroxy-2,6-dimethylphenyl]methyl] (III),

phenol, 4,4^,,4"-(1-methyl-1-propanyl-3-ylidene)tris[2-(1 ,1-dimethyl-ethyl)- 5-methyl (IV), or

phenol, 2,6-bis[[3-(1 ,1-dimethylethyl)-2-hydroxy-5-methylphenyl]- octahydro-4,7-methano-1 H-indenyl]-4-methyl (V)

and

b) at least one phenolic antioxidant selected from the compounds (VI), (VII) or (VIII)

benzenepropanoic acid, 3-(1 ,1-dimethylethyl)-4-hydroxy-5-methyl-, 2,4,8, 10-tetraoxa-spiro[5.5]undecane-3,9-diylbis(2,2-dimethyl-2, 1 - ethanediyl) ester (VI),

tetrakismethylene(3,5-di-tert.butyl-4-hydroxyphenyl)-hydrocinnamate (VII) or

octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (VIII)

wherein the weight ratio of component a) to component b) is from 1 : 10 to 10:1.

2. A stabilizer composition as claimed in claim 1 , wherein component a) is compound (I), (II) or (III) or any mixture thereof.

3. A stabilizer composition as claimed in claim 1 , wherein component a) is compound (I).

4. A stabilizer composition as claimed in any of claims 1 to 3, wherein the weight ratio of component a) to component b) is from 1 :2 to 2:1

5. A stabilizer composition as claimed in claim 1 in combination with sterically hindered phosph(on)ites of the general formulae

Phosphites: P-(OAr)₃

Phosphonites: P-(OAr)₃._n Ar'_n (n =1 ,2; Ar = Ar' or Ar ≠ Ar' )

in which Ar and Ar" have the meaning of an aromatic rest which is preferably substituted by branched alkyl rests.

6. A method of use of a stabilizer composition as claimed in any of claims 1 to 5 wherein an amount of 0.001 to 2.000 % by weight, based on the polymer, is incorporated into a thermoplastic polymer.

7. A method of use of a stabilizer composition as claimed in any of claims 1 to 5 wherein an amount of 0.020 to 0.20 % by weight, based on the polymer, is incorporated into a thermoplastic polymer.

8. A method of use as claimed in claim 6 or 7 wherein the thermoplastic polymer is a polyamide.

9. A process of stabilizing thermoplastic polymers comprising incorporating therein before or during processing a stabilizing quantity of the stabilizing composition according to claims 1 to 5.

10. A process according to claim 9 wherein the stabilizing composition is added in an amount of 0.020 to 0.20 % by weight, based on the thermoplastic polymer.