GB2091732A - Nickel pyrazole/polyalkylpiperidine complexes useful as light stabilizers in polymeric materials - Google Patents

Abstract

Nickel<II> complexes containing per molecule two monodentate 1,3- hydrocarbyl-4-acylpyrazole-5-oxy ligands and one or two 2,2,6,6- tetraalkylpiperidine ligands having at least one hydroxyl, amino or ether group as, or as part of, a 4- substituent, are useful as light stabilizers for polymeric materials, particularly thermoplastic polymers and automotive finishes.

Description

SPECIFICATION Improvements in or relating to organic compounds This invention relates to nickel pyrazol/polyalkylpiperidene complexes, useful as light stabilizers in polymeric materials.

The present invention provides nickel" complexes bearing per molecule two monodentate 1,3hydrocarbyl-4-acylpyrazol-5-oxy ligands, and one or two 2,2,6,6-tetraalkylpiperidine ligands having at least one hydroxyl, amino or ether group as, or as part of, a 4-substituent. The 4-acyl substituent on the pyrazole ligand must be other than formyl. Where only one tetraalkylpiperidine ligand is present, there may in addition be one water molecule as ligand.

As will be appreciated, the 4-acyl-pyrazol-(5)-oxy ligand may bear substituents on the 1,3 hydrocarbyl substituents attached to the pyrazole ring which do not adversely affect the light stabilizing properties or stability of the complexes. The selection of such substituents forms part of the general knowledge in the light stabilizer art.

A preferred group of complexes of the invention are the complexes of formula la,

in which R' is C1~22alkyl; C68cycloalkyl; C7~10aralkyl the acryl ring of which may be substituted by one hydroxyl and/or 1 or 2 C11alkyl groups; phenyl; phenyl substituted by up to 4 groups selected from not more than one m- orp-hydroxyl, not more than 2 C118alkyl or alkoxy groups and not more than 1 phenyl group which may itself be substituted by up to three such substituents; furyl; thiophenyl; benzothiophenyl or benzothiophenyl substituted by up to 2 C14alkyl groups; R1 is C1~4alkyl; phenyl; phenyl substituted by up to 2 C,~18alkyl or alkoxy groups, or one phenyl or one phenoxy group; or 3,5-di-t.butyl-4-hydroxybenzyl; R2 is C1~4alkyl; phenyl; phenyl substituted as in R1; or benzyl; R3 is hydrogen or C14 alkyl; and either R4 is hydrogen and R5 is -OH; -NH2; a group a) or a group b) - X - R6 a)

where X is -0--NH-or NRs where Ra is C14alkyl R6 is C118alkyl which may be interrupted by -0--NH-or -N(C18alkyl)- and which may be substituted by -COOR9 where R9 is C119alkyl and R7 is C2~12alkylene, which may be interrupted by -0- or by -NH- orR4 and R5, together with the carbon atom to which they are attached, form a 5-, 6- 7-membered heterocyclic ring system, preferably 5- or 6-membered, xis 1 or 2 y is O or 1 and (x + y) is 1 or2.

In compounds of formula I, whenever the same symbol appears more than once it may have the same or different significances, unless otherwise stated. All C3 or higher alkyl or alkylene groups may be either straight chain or branched. Any groups capable of bearing substituents are unsubstituted unless otherwise stated.

Preferably R' is R" where R" is C412alkyl, phenyl, or phenyl substituted by a maximum of three substituents selected from 1 or 2 C119alkyl groups and one hydroxyl group or one Alkoxy group.

Preferably it is R"' where R"' is C412alkyl or phenyl, most preferably phenyl.

R1 is preferably R; where R1 is C1~4alkyl, phenyl or (C14alkyl)phenyl, more preferably R;1 where R;' is C14alkyl or phenyl, most preferably phenyl. R2 is preferably R2, where R2 is C14alkyl or phenyl, more preferably C1~4alkyl, particularly methyl. R3 is preferably hydrogen.

Preferably, either R4 is hydrogen and R5 is -NH2, a group a) in which X is -NH- and Re is C112alkyl or -(CH2)m-COOR9 where m is 1-4, preferably 1 or 2 or a group b) in which X is -NH-, R, is C26alkylene, and R3 and R4 are all hydrogen; or R4 and R9 together with the carbon atom to which they are attached form one of the ring systems c)-f)

in which C indicates the carbon atom to which groups R4 and R5 are attached, and in which R10 and R11, independently, are hydrogen, C130alkyl or benzyl; or R10 is hydrogen or C14alkyl and R,1 is phenyl, (C1-4alkyl)-phenyl, chlorophenyl, 4-hydroxy-3,5-t.-butylphenyl or naphthyl; or R10 and R11 together with the carbon atom to which they are attached form a Csi5 cycloalkylidene ring which may be unsubstituted or substituted by one C14alkyl group, or form a group of formula g)

R12 is hydrogen or C1~4alkyl, unsubstituted or substituted by -COOR9, n is 1 or2,

when n = 2, in which r is O or 1 and R15 is hydrogen, methyl, ethyl or hydroxyethyl; p is 1-4, q is 1 or2, R14 is C118alkyl, C5-8cycloalkyl or phenyl when q = 1 and C2-8alkylene or phenylene when q = 2; Y1 and Y2 are independently -0-or-NH-and Z is =O or =S.

Where n = 2 or q = 2, the ring systems d) and f) respectively will be attached to two tetraalkylpiperidine rings, which are preferably identical.

The ring systems preferably contain an amine nitrogen, more preferably an -NH- group.

More preferably, either R4 is hydrogen and R5 is -NH2 or -NHCH2.COOR9 or R4 or Rs together form a ring system c) in which R10 and R11, together with the carbon atom to which they are attached, form a cyclododecylidene ring, and 12 is hydrogen.

The complexes of formula la preferably contain only one molecule of tetraalkypiperidine, that is x is preferably 1.

The compounds corresponding to the separate pyrazole and 2,2,6,6-tetraalkylpiperidine ligands are known or may be made in analogous manner to known compounds from available starting materials.

The invention also provides a process for the preparation of the nickel" pyrazoleitetraalkylpiperidine complexes of the invention characterised in that 1 mole of a complex of 2 moles of the pyrazole ligand with one Ni2+ ion, which may in addition have one or more water molecules as ligands, is reacted with 1 or 2 moles of the 2,2,6,6-tetraalkylpiperidine compound in an inert solvent at elevated temperature, if necessary with removal of water, and the resulting complex isolated by known methods.Suitable solvents include aromatic hydrocarbons e.e. benzene, toluene and xylene, which enable water to be removed by refluxing and separation, e.y. benzene, toluene and xylene, The 2:1 pyrazole/nickel complex which is the starting material for this process may be obtained for example by heating the corresponding pyrazolone compound with nickel acetate, or the pyrazole sodium salt with nickel chloride. Such complexes are also known.

Alternatively, and preferably, the corresponding pyrazolone compound in free or alkali metal salt form and the corresponding tetraalkylpiperidine compound may be simultaneously complexed with a complexable nickel salt. The reaction is effected in known manner, preferably in a solvent such as an alcohol, e.g. ethanol at elevated temperature. The complex usually precipitates out on cooling and precipitation may be initiated or accelerated by addition of water. Examples of nickel salts complexable with the pyrazole sodium salt are the chloride, sulphate and tartrate salts. If the pyrazole free base is used, nickel acetate is preferred.

The complexes of the invention are useful as stabilizers to protect polymeric materials against degradation by light, particularly I UV light. The complexes have good solubility and miscibility in solvent systems and in liquid polymers and prepolymers, which makes them useable in a wide range of polymeric materials.

The concentration of the complex of the invention employed in the polymeric material is suitably 0.01 to 5% by weight, preferably 0.02 to 1% by weight. The compound may be added before, during or after the polymerization step, and may be added in solid form; in solution, preferably as a liquid concentrate containing from 2080% by wt. of the complex or as a solid masterbatch composition containing 2080% by wt. of the complex and 8020% by wt. of a solid polymeric material which is identical with or compatIble with the polymeric material to be stabilized.

Suitable polymeric materials include plastics materials for example polyethylene, polypropylene, ethylene/propylene copolymers, polyvinyl chloride, polyester; polyamide, polyurethane, polyacrylonitrile, ABS, terpolymers or acrylates, styrene and acrylonitrile, styrene/acrylonitrile and styrene/butadiene.

Other plastics materials such as polybutylene, polystyrene, chlorinated polyethylene, polycarbonate, polymethylmethacrylate, polyphenylene oxide, polypropylene oxide, polyacetais, phenol/formaldehyde resins and epoxy resins may also be used. Preferred plastics materials are polypropylene, polyethylene, ethylene/propylene copolymers and ABS. Natural polymers for example natural rubber may also be stabilized, as may lubricating oils containing polymeric material.

The complexes of the invention may be incorporated by known methods into the polymeric material to be stabilized. Or particular importance is blending of the compounds with thermoplastic polymers in the melt, for example in a melt blender or during the formation of shaped articles, including foils, tubes, Fibres and foams by extrusion, injection moulding, blow moulding, spinning or wire coating.

It is not essential for the polymeric material tobe fully polymerised before mixing with the compounds according to the invention. The compounds may be mixed with monomer, prepolymer or precondensate, and the polymerisation or condensation reaction carried out subsequently. This will of course be the preferred method of incorporation of the compounds into thermosetting polymers, which cannot be melt blended.

The complexes of the invention may be used alone or in combination with other stabilizers, for example antioxidants. Examples include sterically hindered phenols, sulphur or phosphorus-containing compounds or mixtures of these. Examples are benzofuran-2-ones; indolin-2-ones and sterically hindered phenols such as 23-(4-hydroxy-3,5-ditert.-butylphenyl)-propionyl stearate, methane tetrakis [m ethylene-3 (3', 5'-ditert.-butyl-4-hydroxyphenyl-)-propionate], 1 ,3,3-tris-(2-methyl-4-hydroxy-5-tert- butylphenyl)-butane, 1 ,3,5-tris(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)-1 ,3,5-triazin-2,4,6 (1 H, 3H, 5H)-trione, bis (4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiolterephthalate, tris (3,5-ditert.-butyl-4 hydroxybenzyl) isocyanura-te, the triester of ,B-(4-hyatroxy-3,5-ditert.-butylphenyl) propionic acid with 1 ,3,4-tris-(2-hydroxyethyl)-5-triazin-2,4,6 (1 H, 3H, 5H)-trione, bis [3,3-bis-(4'-hydroxy-3-tert.butylphenyl)-butyric acid] glycol ester, 1 ,3,5-trimethyl-2,4,6 tris-(3,5-ditert.-butyl-4-hydroxybenzyl) benzene, 2,2'-methylene-bis-(4-methyl-6-tert.-butylphenyl) terephthalate, 4,4-methylene-bis-(2,6 ditert.-butylphenol), 4,4'-butylidene-bis-(tert.-butylmeta-cresol), 4,4-thio-bis-(2-tert. butyl-5methylphenol, 2,2'-methylene-bis-(4-methyl-6-tert.-butylphenol.

Sulphur-containing antioxidative co-stabilizers which may be used include for example distearylthiodipropionate, dilaurylthiodipropionate, methane tetrakis (methylene-3hexylthiopropionate), methane tetrakis (methylene-3-dodecylthiopropionate) and dioctadecyldisulphide.

Phosphorus-containing co-stabilizers include for example trinonylphenyi phosphite, 4,9-distearyl3,5,8,1 O-tetraoxadiphosphaspiroundecane, tris-(2,4-ditert.-butylphenyl)phosphite and tetrakis (2,3ditert.-butylphenyl)-4,4'-biphenylylene diphosphonite. Further additives such as aminoaryl compounds and UV-absorbers and light stabilizers e.g. 2-(2'-hydroxyphenyl)-benzotriazole, 2hydroxybenzophenone, 1 ,3-bis-(2'-hydroxybenzoyl)benzene, salicylates, cinnamates, benzoates and substituted benzoates, sterically hindered amines and oxolic acid diamides may be used. Other known types of additives, e.g. flame retardants and antistatic agents, may also be added.

The complexes of the invention are especially suitable for use in organic polymer-containing coatings, particularly automotive finishes.

Automotive finishes are generally solutions or dispersions of organic polymers or polymer precursors in organic solvents. The majority are stoving finishes, which require the application of heat, generally above 1 000C, in order to harden the finish in an acceptable time once it has been applied to the primer-coated metal surface. The effect of this heating may be to accelerate the chemical reaction between polymer precursors in a thermosetting system, or to bring about fusion of particles of a thermoplastic polymer.

Many automotive finishes are metallic finishes, which contain flakes of metal, usually aluminium, in order to provide optical effects due to reflection. Such finishes are often two-coat finishes, in which a clear top coat is applied over a base coat containing the pigment and metal flakes. Such two-coat metallic finishes have particular need of UV stabilizers in the top coat, since the polymer in this coat is not protected by light-absorbing pigments, and it is subjected to almost double the normal amount of radiation because of reflection of light from the lower metallic layer.

The complexes of the invention are particularly useful in stoving finishes, particularly in the top coat of two-layer metallic finishes.

The complexes of the invention are suitable for use as UV stabilizers in a wide range of liquid finishes, for example those base on combinations of melamineformaldehyde resins with oil-modified polyester resins, polyacrylate resins with added crosslinkers, or saturated polyesters; or on selfcrosslinked polyacrylate or polyacrylate resin copolymerised with styrene.

Further examples are two-component finishes based on an aliphatic or aromatic di-isocyanate and a hydroxy-group-containing polyacrylate, polyester or polyether resin. Thermoplastic polyacrylate resins may also be used, the latter being particularly useful in metallic finishes, as are also polyacrylate resins with added crosslinkers in combination with melamine-formaldehyde resins etherified with butanol and, further, hydroxy-group-containing polyacrylate resins hardened with aliphatic di-isocyanates.

The complex may be added to the finish at any atage in its manufacture, and may be added in solid form or in solution, preferably in the form of a liquid concentrate in a hydrocarbon solvent The addition of from 0.025% by weight, preferably 0.22% by weight of one or more of the complexes of the invention gives a clear improvement in the light- and weather-stability of organic pigments in stoving finishes as well as reducing the tendency to hairline cracking and loss of gloss as the result of weathering. This is surprizingly also found for metallic finishes, and excellent long-term stability of the clear top coat of two-layer metallic finishes is obtained. In such finishes, the complex may be added to the metallic undercoat, the clear top coat or both, preferably only to the clear top coat.

The following Examples, in which all parts are by weight and all temperatures in degrees Centigrade, illustrate the invention.

EXAMPLE 1 5.5 Parts 1 -phenyl-3-methyl-4-benzoylpyrazolone and 6.2 parts 2,2,6,6-tetramethyl-4- aminopiperidine are added to 20 ml ethanol and warmed to SOC, giving a clear solution. The solution is treated with 2.5 parts nickel" acetate tetrahydrate and the resulting green solution is stirred at 700 for 1 hour, cooled and poured into ice water The resulting precipitate is collected by filtration, washed with water and dried. A green product of formula

m.p. 1 1 1--1 150, is obtained.

EXAMPLE 2 7.6 Parts of the nickel complex of formula

is treated with 3.6 parts of the compound of formula 2a)

in 100 ml xylene under reflux for 3 hours, with separation of water. A dark green solution is obtained from which the xylene is removed by distillation to give a green solid residue. Pulverization gives a green powder, m.p. range 1300 (sintering), 14O1470 (melting to clear green liquid) which is the water-free complex of 2 moles of the pyrazole and 1 mole of the tetramethylpiperidine compound per atom of nickel.

EXAMPLES 3-13 By repeating the procedure of Examples 1 and 2 with appropriate starting materials, the complexes listed in Table 1 are obtained, either having 2 moles pyrazole to 1 mole piperidine plus 1 mole water (procedure of Example 1) or as water-free complexes having 2 moles of pyrazole to 1 mole piperidine (procedure of Example 2).

TABLE I Complexes of formula

No. R1 R R4 R51 3 CH3 &commat; 3 CH3 4 n n çOCH3 H U 5 U C3H7 42 6 1 Clt3 CfJ-3 7 HO CH2- CH3 U U U 0-C (CH) 8 i o CH3 C - i211 NE 0 9 CH CH3 U 0 - CCH) 10 0 CE3 -C9E19 2 ii 0 11 HOWCH2 H HO CH22 12 CH3 U U 13 l l n The compound of Example 13 in water free form has m.p. 1 52--1 560.

APPLICATION EXAMPLE A 0.5% by wt. of the compound of Example 1 is worked into polypropylene (containing no UV stabilizer) in a kneading mixer at 1 800. The resulting mass is pressed into a 3 mm thick plate, and also into a 0.3 mm thick film. The film is illuminated in an Atlas Weatherometer WRC 600 with a xenon lamp, and the damage caused by UV light is measured by the growth in intensity of the IR carboxyl band absorption at 5.8 ,u. According to test method DIN 53453, the change in impact strength of samples cut from the 3 mm plate is measured after exposure in the Atlas Weatherometer. In both cases the results obtained are better than those using unstabilized polymer.

APPLICATION EXAMPLE B A two-layer metallic finish is prepared having the following composition: a) base coat 1 2.6 parts commercial polyacrylate resin, with added cross-linking as defined in DIN 53 1 86 (Viacryl) SC 344, Vianova, Vienna, supplied as 50% solution in xylene/butanol 4:1) 2.1 9 parts commercial butanol-etherified melamine resin, medium reactive, prepared by condensation of 1 mol melamine with 3-6 mole formaldehyde, etherified with 3-6 mole butanol according to DIN 53 187 (Maprenal MF 800, Casella, supplied as 72% solution in isobutanol) 0.96 parts butanol 0.26 parts colloidal silicic acid 7.05 parts xylene 52.0 parts of a 20% cellulose acetate butyrate solution of the following composition by weight: 20% cellulose acetate butyrate: acetyl content 13.6%, butyryl content 38.7%, hydroxyl content 1.25%, viscosity of 20% solution in acetone = 200 cp 10% butanol 35% xylene 35% butyl acetate 6.80 parts non-leafing aluminium paste, supplied as 65% suspension in alkylglycol acetate according to DIN 55 923 18.14 parts butyl acetate 0.3 parts copper phthalocyanine blue (C.l. Pigment Blue 15::1) b) top coat 80.00 parts polyacrylate resin (as in the base coat) 13.75 parts melamine resin (as in the base coat) 4.50 parts butyl glycollate 7.50 parts aromatic hydrocarbon solvent, b.p. 186--2120 6.00 parts aromatic hydrocarbon solvent, b.p. 1 55-1 780 c) appllcatlon The base coat is applied to primer-coated metal plates by spraying, giving a layer approx. 20 ym thick, without UV stabilizer. After drying of the base coat, the plates are sprayed with i) top coat as in b) above, without UV stabilizer, or ii) top coat as in b) above, containing 1 part (i.e. 1% by wt.) of the compound of Example 1, added as an 80% solution in xylene, and stoved at 1400 for 30 minutes. Exposure tests show superior results for the plates coated with top-coat ii).

The compounds of Examples 2-13 can be used in analogous manner to Application Examples A and B.

Claims (27)

1. A nickel" complex bearing per molecule two monodentate 1 ,3-hydrocarbyl-4-acyl-pyrazol-5-oxy ligands, and one or two 2,2,6,6-tetraalkylpiperidine ligands having at least one hydroxyl, amino or ether group as, or as part of, a 4-substituent, provided that the 4-acyl substituent on the pyrazole ligand must be other than formyl.

2. A complex as claimed in Claim 1 of formula la

in which R' is C1~22alkyl; C69cycloalkyI; C7~10aralkyl the aryl ring of which may be substituted by one hydroxyl and/or 1 or 2 Alkyl groups; phenyl; phenyl substituted by up to 4 groups selected from not more than one m- orp-hydroxyl, not more than 2 C,~,8alkyl or alkoxy groups and not more than 1 phenyl group which may itself be substituted by up to three such substituents; furyl; thiophenyl; benzothiophenyl or benzothiophenyl substituted by up to 2 Alkyl groups; R, is C,~4alkyl; phenyl; phenyl substituted by up to 2 C18alkyl or alkoxy groups, or one phenyl or one phenoxy group; or 3,5-di-t.-butyl-4-hydroxybenzyl; R2is C1alkyl; phenyl; phenyl substituted as in R1; or benzyl; R3 is hydrogen or C,~4alkyl; and either R4 is hydrogen and R5 is -OH; -NH2; a group a) or a group b) - X - R6 a)

where X is -O-, -NH- or -NR8- where This is Alkyl R6 is C1-18alkyl which may be interrupted by -O-, -NH-, or -N(C18alkyI)- and which may be substituted by -COOR9 where R9 is C1-18alkyl.

and R7 is C2-12alkylene, which may be interrupted by -0-or by -NHor R4 and R5, together with the carbon atom to which they are attached, form a 5-, 6- or 7-membered heterocyclic ring system, x is 1 or2 y is 0 or 1 and (x + y) is 1 or 2.

3. A complex according to Claim 2 in which R' is R" where R" is C4~,2alkyl, phenyl, or phenyl substituted by a maximum of three substituents selected from 1 or 2 C 18al kyl groups and one hydroxyl group or one C1-4alkoxy group.

4. A complex according to Claim 2 or Claim 3 in which R, is R1' where R1' is C1~4alkyl, phenyl or (C1~4alkyl) phenyl.

5. A complex according to any one of Claims 2-4 in which R2 is R2 where R2 is C1-4alkyl or phenyl.

6. A complex according to any one of Claims 2-5 in which R3 is hydrogen.

7. A complex according to any one of Claims 2-6 in which either R4 is hydrogen and R5 is -NH2, a group a) stated in Claim 2 in which X is -NH- and Re is C4-12alkyl or -(CH2)m-COOR9 where m is 1-4, or a group b) stated in Claim 2 in which X is -NH-, R7 is C2-6-alkylene, and R3 and R4 are all hydrogen; or R4 and R5 together with the carbon atom to which they are attached form one of the ring systems c)-f)

in which C indicates the carbon atom to which groups R4 and R5 are attached, and in which R10and R11, independently, are hydrogen, C130alkyl or benzyl; or R10 is hydrogen or Alkyl and R11 is phenyl, (C1-4alkyl)-phenyl, chlorophenyl. 4-hydroxy-3,5-t.-butylphenyl or naphthyl; or R10 and R11 together with the carbon atom to which they are attached form a C5-15 cycloalkylidene ring which may be unsubstituted or substituted by one C14al kyl group, or form a group of formula g)

R.2 is hydrogen or C1-4alkyl, unsubstituted or substituted by -COOR9, n is 1 or 2,

when n = 2, in which r is O or 1 and R,5 is hydrogen, methyl, ethyl or hydroxyethyl; pis 1-4,qis 1 or2, R14 is C119alkyl, C5~8cycloalkyl or phenyl when q = 1 and C28alkylene or phenylene when q = 2; Y1 andY2 are independently -0-or -NH- and Z is =O or =S.

8. A complex according to Claim 7 in which either R4 is hydrogen and R9 is -NH2 or -NHCH2.COOR9 or R4 and R5 together form a ring system c) in which R10 and R, together with the carbon atom to which they are attached, form a cyclododecylidene ring, and R,2 is hydrogen.

9. A complex according to any one of the preceding claims containing one mole of tetraalkylpiperidine ligand per atom of nickel.

1 0. A complex according to Claim 1 substantially as described with reference to any one of Examples 1-12.

11. A process for the preparation of a complex according to Claim 1 characterized in that 1 mole of a complex of 2 moles of the pyrazole ligand with one Ni2+ ion, which may in addition have one or more water molecules as ligands, is reacted with 1 or 2 moles of the 2,2,6,6-tetraalkylpiperidine compound in an inert solvent at elevated temperature, if necessary with removal of water, and the resulting complex isolated by known methods.

12. A process for the preparation of a complex according to Claim 1 characterized in that the corresponding pyrazolone compound in free or alkali metal salt form and the corresponding tetraalkylpiperidine compound are simultaneousiy complexed with a complexable nickel salt.

13. A process for the preparation of a complex according to Claim 1 as described in Example 1 or Example 2.

14. A process for the stabilization of polymeric materials against the effect of light comprising the incorporation of from 0:01 to 5% by weight of a complex according to any one of Claims 1-10 into the polymeric material to be stabilized.

15. A process as claimed in Claim 14 in which the polymeric material is a thermoplastic polymer.

1 6. A process as claimed in Claim 15 in which the compound of formula I is incorporated by melt blending.

1 7. A process as claimed in Claim 16 in which the complex is added in the form of a solid masterbatch composition containing 20-80% by wt. of the complex and 8020% by wt. of a solid polymeric material which is identical with or compatible with the polymeric material to be stabilized.

18. A process as claimed in Claim 14 in which the polymeric material is an automotive finish.

19. A process as claimed in Claim 18 in which the complex is incorporated by mixing the finish with a liquid concentrate containing from 2080% by weight of the complex.

20. A polymeric material stabilized against the effects of light, containing from 0.01 to 5% by wt.

of a complex according to any one of Claims 1-10.

21. A stabilized polymeric material as claimed in Claim 20 in which the polymeric material is polypropylene, polyethylene, an ethylene/propylene copolymer or ABS.

22. A solid masterbatch composition containing 2080% by wt. of a complex according to any one of Claims 'i 1-10 and 8020% by weight of a solid thermoplastic polymer.

23. A liquid concentrate containing 2080% by weight of a complex according to any one of Claims 1-10 dissolved in a hydrocarbon solvent.

24. A liquid stoving automotive finish for application to a metal surface, containing 0.025% by weight of a complex according to any one of Claims 1-10.

25. A liquid stoving automotive finish for application as the clear top coat in a two-layer metallic finish, containing 0.02-5% by weight of a complex according to any one of Claims 1-10.

26. A liquid stoving automotive finish containing a complex according to Claim 1, substantially as described with reference to Application Example B.

27. A cured automotive finish obtained by applying and stoving a liquid finish as claimed in any of Claims 24 to 26.