STABILISATION OF PAINTS WITH SPIROINDANE DERIVATIVES

Abstract: Paint or coating compositions are stabilized by spiroindane compounds of formula (I) wherein the numbered radicals R have the meanings given in claim 1, and optionally phosphite stabilizers and phenolic antioxidants.

Description: Stabilisation of Paints with Spiroindane Derivatives The invention relates to coating compositions containing spiroindane compounds and to novel spiroindane compounds. Antioxidants are needed in thermosetting coatings to prevent oxidation of the binder on curing and overbaking. NOχ present in the burner gases of ovens causes an additional problem by reacting, with preferentially aromatic components in the binder, to form yellow breakdown products. It is the usual practice in paints to use a stabiliser combination of a hindered phenol and a phosphite, for example octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or tetrakis- (3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane with 2,4-di-tert- butylphenylphosphite. For better gas oven stability a phosphite is usually used alone. DE-A-4306 747 teaches the use of the combination of a phosphite and a 2,2,6,6- tetramethylpiperidine compound (HALS) in one molecule as stabiliser for powder paints. Phosphites on their own give only slight protection against oxidation in air. In the presence of NO x they mostly do not yellow, but remain largely ineffective. The hindered phenols give much better protection against oxidation, particularly when used together with phosphites, but are themselves highly prone to yellowing in the presence of NOχ. A number of patents by Fuji Photo Film KK claim the spiroindanes and their use in colour photographic films and papers as light fading preventing agents for the magenta pyrazolone- azomethine and pyrazolotriazole-azomethine dyes: GB-A-2077 455, DE-A-3221 883, JP-A- 57204 035. US-A-5 411 847 claims similar structures in photographic applications. The present invention is based on the discovery that the problem of yellowing of paints on curing in gas(or oil-)-fired ovens can be solved through use of certain specific spiroindane derivatives, either alone or with other stabilisers, preferably phosphites. The invention relates to a composition comprising: (A) a paint or coating material (B) at least one compound of formula (I) wherein R-] ,R2. R3 and R4 are independently of one another: a) C-f -Ci 8 unsubstituted alkyl or C * ι -Ci βalkyi substituted by one or more of the groups OH, Cι-C * |8alkoxy, C2-C * i8alkenyloxy, halogen, phenoxy (which is unsubstituted or substituted by C1-C1 βalkyi, Cι-C * ιβalkoxy or halogen), - COORβ, -CONH2, -CONHRgor -CONR9R10; b) C5-Ci2cycloalkyl which is unsubstituted or substituted by OH or -OCOR11 ; c) a five or six-membered heterocycle that is saturated or unsaturated; d) C7-C11 phenylalkyl, which is unsubstituted or substituted by one or more OH, CI or CH3; e) C2-C-|8alkenyl; f) C4-C30 alkyl which is interrupted by one or more O atoms and can be substituted by OH; g) -CO-R12 or -(CH2) n -CO-R * i2 ; h) -SO2-R13; i) a group j) a group k) a group n is 1 to 18; R5 is H, C1-C18 straight chain or branched alkyl, C2-Cιβalkenyl or C6-Ci2aryl; Rβ and R7 are independently of one another H, halogen, C1-C1 βalkyi, C2-C6alkenyl, Ci -Ci 2alkoxy or C2-C12alkenyloxy; Rβ is C1-C1 βalkyi, C2-Cιβalkenyl, C3-C20 alkyl which is interrupted by one or more O, NR9 or S and /or substituted by OH, C-| -C4alkyl which is substituted by -P(O)(ORιβ)2. C3-Cβalkynyl or C7-C11 phenylalkyl; Rg and R10 are independently of one another Cι-C-|2alkyl, C3-Ci2alkoxyalkyl, C4- Ciβdialkylaminoalkyl or C5-C * i2cycloalkyl, or R9 and R10 together are C3- Cgalkylene or C3-Cgoxaalkyiene or C3-Cgazaalkylene; Rl 1 is C1-C1 βalkyi, C2-C1 βalkenyl or phenyl; R*I2 is C1-C1 βalkyi, C2-C1 βalkenyl, phenyl, Ci -Ci 2alkoxy, phenoxy, C1- Ci2alkylamino or C6-Ci2arylamino or a group -R-jg-COOH; R13 is Cι-Ci2alkyl, C6-Ci2aryl or C7-Ci4alkaryl; R14 is hydrogen, oxyl, hydroxy, -CH2CN, C1-C1 βalkyi, C1-C18- alkoxy, C3- Cβalkenyl, C3-Cβalkynyl, Cs-Cβcycloalkyl or -alkoxy, phenyl, naphthyl, C7- Ci2phenylalkyl or -alkoxy, phenyl or phenylalkyl substituted by alkyl or phenyl of 7- 14 carbon atoms, C3-C5alkenoyl, C * |-Cιβalkynoyloxy, benzyloxy or a group CH2- CH(OH)-Z where z is H, CH3 or Phenyl, or a group of the formula wherein D' is C1-C1 βalkyi, Cι-Cιβalkoxy, phenyl, or phenyl substituted by hydroxy, C- * - Cβalkyl, Ci-Cβalkoxy, amino or amino mono- or disubstituted by C-j -Cβalkyl or phenyl. R15 is H, C1-C1 βalkyi or C3-C1 βalkyi interrupted by one or more oxygen atoms, cyanoethyl, benzyl, glycidyl, a monovalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acid, or of carbamic acid, or of a phosphorus- containing acid, or a monovalent silyl radical -Si(R2l)(R22)(R23); Rl 6 is H, -CO-R-11 , -Si(R2l)(R22)(R23) . or -COOR24; I R17 is C1-C18 alkyl, C2-C18 alkenyl, phenyl-Ci -C4alkyl, C3-C24alkyl or C2- C-|4hydroxyalkyl, each of which is interrupted by one or more O atoms, or is phenyl, which is unsubstituted or substituted by C-j-C4alkyl, C-|-C4alkoxy or halogen, C5- Ci2cycloalkyl which is unsubstituted or substituted by 1 - 3 C-|-Cβ alkyl, or -COR- * 1 , or 18 is C1-C1 βalkyi or phenyl; Rig is Cι-Cιβalkylene, vinylene or phenylene; R20 is H, OH, oxyl, C1-C1 βalkyi, C2-Ciealkenyl, Cι-Cιβalkoxy, C5-C-j2cyc.oa.kyl, C5- Ci2cycloalkoxy, C3-Cβalkynyl, C7-Ci2phenylalkyl, Ci-Cβalkanoyl, C3-C5alkenoyl or glycidyl; R21. R22 and R23 are independently of one another C-j-Cβalkyl or phenyl; R24 is Cι-C4alkyl. Preferred spiroindane derivatives which can be used according to the invention are of formula I, wherein R5 is H; 1 ,R2. R3 and R4 are the same and can be a) Ci -Ci β straight chain or branched alkyl, optionally substituted by one or more of the groups OH, d-Ciβalkoxy, C2-Cιβalkenyloxy, -COORβ, -CONH2, - CONHRg, -CONRgRio; b) C5-Ci2cycloalkyl which is unsubstituted or substituted by OH or -OCOR-* 1 ; c) tetrahydropyran; e) C2-Cιβalkenyl; f) C4-C30 alkyl which is interrupted by one or more O atoms and can be substituted by OH; g) -CO-R12 or -(CH2) n-CO-Rι 2 ; ; i) a group i) a group k) a group n is 1 to 18; Rβ and R7 are independently of one another H or Ci-Cβalkyl ; Rβ is C1-C1 βalkyi, C2-Cιβalkenyl, C3-C20 alkyl which is interrupted by one or more O or substituted by OH or is C3-Cβalkynyl; Rg and R-|rj are independently of one another C * |-Ci2alkyl, C3-C * i2alkoxyalkyl or C5- Ci2cycloalkyl; Rl 1 is C1-C1 βalkyi or C2-C1 βalkenyl; R12 is C1-C1 βalkyi, C2-C1 βalkenyl, C-|-C-|2alkoxy, Cι-Ci2alkylamino or a group - R19-COOH, is especially C-|-Ci2alkyl, allyl, cyclohexyl, benzyl, acetyl, acryloyl, Cyclohexyloxy or Cι-Ci2-alkyoxy R15 is H or C1-C1 βalkyi optionally interrupted by one or more oxygen atoms; R-lβ is H, -CO-R11 , -Si(R2l)(R22)(R23) , or -COOR24; ; R * l7 is C1-C18 alkyl, C2-C18 alkenyl, C3-C24al yl or C2-C-|4hydroxyalkyl, each of which is interrupted by one or more O atoms, C5-Ci2cycloalkyl which is unsubstituted or substituted by 1 - 3 C-i-Cβ alkyl, or -COR11 , or R19 is Ci-C-jβalkylene or vinylene; R20 is H, OH, oxyl, C1-C1 βalkyi, C2-C1 βalkenyl, Cι-Cιβalkoxy, C5-Ci2cycloalkyl, C5- Ci2cycloalkoxy, C3-Cβalkynyl, Ci-Cβalkanoyl, C3-Csalkenoyl or glycidyl; R21. R22 and R23 are independently of one another C-j-Cβalkyl; R24 is C * |-C4a!kyl. Particularly preferred spiroindane derivatives which can be used according to the invention are of formula I wherein R5, Re and R7 are H; Rl .R2. R3 and R4 are the same and can be either: a) C1-C18 straight chain or branched alkyl; b) cyclohexyl; e) allyl; f) C3-C12 alkyl which is interrupted by one or more O atoms; g) -CO-Ri2 ; i) a group j) a group k) a group n is 1 to 6; R12 is Ci -C4alkyl or C2-C3alkenyl; R14 is C-|-Ci2alkyl, benzyl, or Cs-CβcycloalkyI; most preferably C6-C*ιoalkyl or cyclohexyl. R * l5 is H or C-|-C * t βalkyi optionally interrupted by one or more oxygen atoms; R * l6 is H, -CO-R11 or -COOR24 ; R17 is C1-C18 alkyl, C2-C 8 alkenyl, C3-C24alkyl or C2-C14hydroxyalkyl, each of which is interrupted by one or more O atoms or is C5-C-|2cycloalkyt; or is R20 is H, Ct-Cβalkyl, acetyl, propargyl, acryloyi, Ci-Cβalkoxy or C5-Ci2cycloalkyl; R24 is Cι-C4alkyl. An alkyl radical of 1 to 30 carbon atoms may be straight-chain or branched and be typically: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl, henicosyl, docosyl, 2-ethylbutyl, 1- methylpentyl, 1 ,3-dimethylbutyl, 1 ,1,3,3-tetramethylbutyl, 1-methylhexyl, isoheptyl, 1- methylheptyl, 1 ,1,3-trimethylhexyl, 1,1 ,3,3-tetramethylhexyl or 1-methylundecyl. Preferably Rl is an alkyl radical of 1 to 1 βcarbon atoms. Examples of alkoxy radicals are derived from the above groups by addition of the group -0-. Alkenyl radicals are derived from alkyl radicals by the replacement of one or more than one C-C single bond by C=C double bonds. Allyl and isoallyl are preferred. Alkenyloxy is derived from alkenyl by adding -0-. Illustrative examples for alkenyl of 2 to18 carbon atoms are vinyl, allyl, 2-methallyl, butenyl such as 2-butenyl, hexenyl such as 2-hexenyl, decenyl, undecenyl such as 10-undecenyl, heptadecenyl or oleyl. C5-C * i2cycloalkyl radicals typically include cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and cyclododecyl. Cyclopentyl, cyclohexyl and cycloheptyl are preferred and cyclohexyl is particularly preferred. Cycloalkoxy radicals and cycloalkoxycarbonyl radicals are derived from said C5-C-|2cycloalkyl radicals by adding -CO- or -O-CO- groups. Phenyl-Ci-4alkyl and C7-C9phenylalkyl are typically Jaenzyl, phenethyl, 3-phenylpropyl, a- methylbenzyl and a,a-dimethylbenzyl. Benzyl is preferred. Typical examples of the above unsubstituted or C-i-Cβalkyl-substituted cycloalkyl groups of 5 to 12 carbon atoms are cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, 2- or 4- methylcyclohexyl, dimethylcyciohexyl, trimethylcyclohexyl, tert-butylcyclohexyl. Cyclohexyl is especially preferred. C3-Cβalkynyl is derived from the alkyl radicals having 3 to 8 C atoms in which 2 C atoms are connected by a triple bond and is preferably propargyl. C6-Ci2-aryl refers to e.g. phenyl or naphthyl. C7-C*i8Phenylalkyl can be typically benzyl, 1- or 2-phenylethyl, 3-phenylpropyl, a,a- dimethylbenzyl, 2-phenylisopropyl, 2-phenylhexyl or benzhydryl. Benzyl is preferred. C7-Cιβalkylphenyl may contain linear or branched alkyl groups, the number of said alkyl groups being 1 to 3, preferably 1 or 2. Illustrative examples are tolyl, ethylphenyl, isopropylphenyl, tert-butylphenyl, sec-pentylphenyl, n-hexylphβnyl, tert-octylphenyl, isononylphenyl or n-dodecylphenyl. Any 5- to 7-membered heterocyclic ring metionend above may contain 1 or 2 a N- or O- atoms and is preferably a saturated ring, more preferably a 6-membered ring. Such a ring is typically the piperidine, hexamethyleneimine, piperazine or morpholine ring. Alkylene of 1 to12 carbon atoms can be typically methylene, ethylene, trimethylene, 2,2- dimethyl- ,3-propanediyl, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene or dodecamethylene. Trimethylene, tetramethylene, hexamethylene and octamethylene are preferred. Alkylene which is interrupted by oxygen atoms, preferably by 1 or 2 oxygen atoms, may be 3- oxapentane-1 ,5-diyl; 3,6-dioxaoctane-1 ,8-diyl; 2-oxapropane-1,3-diyl; 2,7-dioxaoctane-1 ,8- diyl or 2,6-dioxa-4,4-dimethyl-1 ,7-heptanediyl. Alkenylene of 2 to 12 carbon atoms may contain one or more double bonds, preferably one double bond, and be straight-chain or branched. Illustrative examples of such alkenyl radicals are: vinylene, alkylene, 2-methalkylene, 2-hexenylene, 2-methyl-3-butenylene, 4- propyl-2-pentenylene, 2-decenylene or dodecenylene. Alkenylene which is interrupted by 1 or 2 oxygen atoms may be 3-oxa-5-heptenylene, 2,7- dioxa-4-octenylene, 3,8-dioxa-5-decenylβne or 3-oxa-5,8-undecadienylene. Phenyl-Ci-4-alkyl and C7-Cg-Phenylalkyl can be benzyl, phenethyl, 3-phenylpropyl, a- methylbenzyl und a,a-dimethylbenzyl. Benzyl is preferred. The compounds of the invention can be produced by known methods, as described, for example in J. Chem. Soc 1934, 1678, US-A-5,422,847, GB-A-2062888, DE-A-3221883 and GB-A-2077455. Examples of compounds of formula I are: Abbreviations: Et = Ethyl, Pr -= Propyl, Bu = Butyl, Bz = Benzyl The invention relates also to novel compounds of formula I as described above, in which at least one of R*ι to R4 is a group i), j) or k) wherein R17 is a group The spiroindane derivatives generally do not stabilise against oxidation by air, but are very effective in preventing attack by NO x . This effect has nowhere been described in the literature. They also do not yellow in the presence of NOχ. The combination of a spiroindane derivative and a phosphite therefore offers the first effective solution to the problem of discoloration caused by attack of NO x on (aromatic) components of paint binders. The spiroindane derivatives are resistant to oxidation, non-volatile, thermally stable, readily soluble, colourless and can be easily manufactured from cheap starting materials (acetone + catechol). For use in powder coatings there is a general limitation which concerns compounds having a high melting point. The compounds of the invention with the appropriate substituion, as illustrated by examples A1 to A24, have a conveniently low melting point. The novel coating composition preferably comprises 0.01-10 parts by weight of B, in particular 0.05-10 parts by weight of B, especially 0.1-5 parts by weight of B, per 100 parts by weight of solid paint or coating material A. Multilayer systems are also possible here, where the concentration of the stabilizer (component B) in the outer layer can be higher, for example from 1 to 15 parts by weight of B, especially 3-10 parts by weight of B, per 100 parts by weight of solid component A. The use of the novel mixture as stabilizer in coatings has the additional advantage that delamination, i.e. peeling-off of the coating from the substrate, is prevented. This advantage is particularly important in the case of metallic substrates, including in the case of multilayer systems on metallic substrates. The binder can in principle be any binder which is customary in industry, for example those as described in Ullmann's Encyclopedia of Industrial Chemistry, 5thEdn., Vol.A18, pp.368- 426, VCH, Weinheim, 1991. In general, this is a film-forming binder based on a thermoplastic or thermosetting resin, predominantly based on a thermosetting resin. Examples thereof are alkyd, acrylic, polyester, phenolic, melamine, epoxy and polyurethane resins and mixtures thereof. The binder can be cold-curable or hot-curable; it may be advantageous to add a curing catalyst. Suitable catalysts which accelerate curing of the binder are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, V0I.AI8, p.469, VCH Veriagsgesellschaft, Weinheim, 1991. Preference is given to coating compositions in which component A contains a binder comprising a functional acrylate resin and a crosslinking agent. Examples of coating compositions containing specific binders are: 1. Paints based on cold- or hot-crosslinkable alkyd, acrylate, polyester, epoxy or melamine resins, or mixtures of such resins, if desired with addition of a curing catalyst; 2. Two-component polyurethane paints based on hydroxyl-containing acrylate, polyester or polyether resins and aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; 3. One-component polyurethane paints based on blocked isocyanates, isocyanurates or polyisocyanates which are deblocked during baking; 4. Two-component paints based on (poly)ketimines and aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; 5. Two-component paints based on (poly)ketimines and an unsaturated acrylate resin or a polyacetoacetate resin or a methacrylamidoglycolate methyl ester; 6. Two-component paints based on carboxyl- or amino-containing polyacrylates and polyepoxides; 7. Two-component paints based on anydride-containing acrylate resins and a polyhydroxyl or polyamino component; 8. Two-component paints based on acrylate-containing anhydrides and polyepoxides; 9. Two-component paints based on (poly)oxazolines and anhydride-containing acrylate resins or unsaturated acrylate resins or aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; 10. Two-component paints based on unsaturated polyacrylates and polymalonates; 11. Thermoplastic polyacrylate paints based on thermoplastic acrylate resins or externally crosslinking acrylate resins in combination with etherified melamine resins; 12. Paint systems based on siloxane-modified or fluorine-modified acrylate resins. in addition to components A and B, the novel coating composition preferably comprises, as component C, a phosphite compound. In addition to components A, B and, if used, C, the coating composition can comprise further components, for example solvents, pigments, dyes, plasticizers, stabilizers, thixotropic agents, drying catalysts and/or flow-control agents. Examples of possible components are those as described in Ullmann's Encyclopedia of Industrial Chemistry, 5thEdn., Vol.A18, pp.429-471 , VCH, Weinheim, 1991. Possible drying catalysts or curing catalysts are, for example, organometallic compounds, amines, amino-containing resins and/or phosphines. Examples of organometallic compounds are metal carboxylates, in particular those of the metals Pb, Mn, Co, Zn, Zr and Cu, or metal chelates, in particular those of the metals Al, Ti and Zr, or organometallic compounds, for example organotin compounds. Examples of metal carboxylates are the stearates of Pb, Mn and Zn, the octanoates of Co, Zn and Cu, the naphthenates of Mn and Co and the corresponding linoleates, resinates and tallates. Examples of metal chelates are the aluminium, titanium and zirconium chelates of acetylacetone, ethyl acetylacetate, salicyl aldehyde, salicyl aldoxime, o- hydroxyacetophenone and ethyl trifluoroacetylacetate, and the alkoxides of these metals. Examples of organotin compounds are dibutyltin oxide, dibutyltin dilaurate and dibutyltin dioctanoate. Examples of amines are in particular tertiary amines, for example tributylamine, triethanolamine, N-methyldiethanolamine, N-dimethylethanolamine, N-ethylmorpholine, N- methylmo holine and diazabicyclooctane (triethylenediamine) and salts thereof. Further examples are quaternary ammonium salts, for example trimethylbenzylammonium chloride. Amino-containing resins are simultaneously binder and curing catalyst. Examples thereof are amino-containing acrylate copolymers. The curing catalyst can also be a phosphine, for example triphenylphosphine. The novel coating compositions can also be radiation-curable. In this case, the binder essentially comprises monomeric or oligomeric compounds containing ethylenically unsaturated bonds which are cured, after application, by actinic radiation, i.e. are converted into a crosslinked, high-molecular-weight form. UV-curing systems generally additionally contain a photoinitiator. Corresponding systems are described in the abovementioned publication, Ullmann's Encyclopedia of Industrial Chemistry, 5thEdn. Vol.A18, pages 451- 453. In radiation-curable coating compositions, the novel stabilizer mixtures can also be employed without addition of sterically hindered amines. The novel coating compositions can be applied to any desired substrates, for example to metal, wood, plastic or ceramic materials. The stabilizers of the invention are used preferably in systems subjected to high temperatures, such as powder paints and coil coatings, but also in systems in which the needs to prevent discoloration are great, such as in top coats. The novel coating compositions can be applied to the substrates by conventional processes, for example by brushing, spraying, pouring, dipping or electrophoresis; see also Ullmann's Encyclopedia of Industrial Chemistry, 5thEdn., V0I.AI8, pp. 491-500. The curing of the coatings can - depending on the binder system - be carried out at room temperature or by warming. The coatings are preferably cured at 50-150°C, powder coatings usually at higher temperatures, and coil coatings at temperatures up to as much as 300°C. The coatings obtained in accordance with the invention have excellent resistance to the harmful effects of oxygen and heat. The invention therefore also relates to a coating, in particular a paint, which has been stabilized against the harmful effects of light, oxygen and heat by a content of the novel mixture comprising compounds of the formula I. The paint is preferably a top coat for automobiles, a powder paint or a coil coating. The invention furthermore relates to a process for stabilizing a coating based on organic polymers against damage by light, oxygen and/or heat, which comprises admixing a mixture comprising a compound of the formula I and a compound of the formula II with the coating composition, and to the use of a mixture comprising compounds of formula I in coating compositions as stabilizers against damage by light, oxygen and/or heat. The coating compositions can comprise an organic solvent or solvent mixture in which the binder is soluble. However, the coating composition can also be an aqueous solution or dispersion. The vehicle can also be a mixture of an organic solvent and water. The coating composition can also be a high-solids paint or contain no solvent (powder paint). The pigments can be inorganic, organic or metallic pigments. The novel coating compositions preferably contain no pigments and are used as clear coats. Likewise preferred is the use of the coating composition as top coat for applications in the automobile industry, in particular as a pigmented or unpigmented top coat of the finish. However, use for underlying layers is also possible. Coating compositions usually consist of binders, additives and, optionally, chromophoric components. Suitable binders are in principle all those customary in the art, for example those described in Ullmann's Encyclopedia of Industrial Chemistry, 5. Ed., Vol. A18, pp. 368-426, VCH, Weinheim 1991. The binder is usually a film-forming binder based on a thermoplastic or thermocurable resin, preferably on a thermocurable resin. Typical examples are alkyd resins, acrylic resins, polyester resins, phenolic resins, melamine resins, epoxy resins, polyurethane resins and mixtures thereof. The binder may be a cold-curable or hot-curable binder and the addition of a curing catalyst may be advantageous. Suitable catalysts which accelerate the full cure of the binder are described, inter alia, in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A18, p.469, VCH Veriagsgesellschaft, Weinheim 1991. Preferred coating compositions are those containing as film-forming binder epoxy resins, polyurethane resins, polyester resins, acrylic resins and the copolymer resins thereof, polyvinyl resins, phenolic resins, alkyd resins or mixtures of such resins. If the novel compositions are coating compositions or paint systems, then these may contain further customary components, typically selected from the group consisting of the dyes, pigments, fillers, flow control agents, adhesion promoters, curing catalysts, light stabilisers or antioxidants. The compounds are used preferably alone and mixed together with other stabilisers in liquid and powder paints. For use in powder coatings, solid compounds with melting points in the range 50 - 100°C are strongly preferred for reason of their ease of handling and for their easier incorporation during extrusion. An example of such a compound having good activity and a suitable melting point (80°C) is: The compounds of the formula I are known and their preparation is described, for example, in US-A-4 612 049. Their use in powder coatings is a particularly preferred field where the invention is useful. Interest attaches to powder coatings comprising as component (ii) at least one calcium- modified silicate pigment in which the calcium content is from 2 to 7% by weight. The definition of "powder coatings" is understood to be that as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th, Completely Revised Edition, Vol. A 18, pages 438 to 444 (1991) in Section 3.4. Powder coatings are understood as thermoplastic or stovable, crosslinkable polymers which are applied in powder form to predominantly metallic substrates. The manner in which the powder is brought into contact with the workpiece to be coated characterizes the various application techniques, such as, for example, electrostatic powder spraying, electrostatic fluidized-bed sintering, bed sintering, fluidized-bed sintering, rotational sintering or centrifugal sintering. Preferred organic film-forming binders for the powder coating composition according to the invention are stoving systems based on, for example, epoxy resins, polyester resins, epoxy- polyester resins, polyester cured with hydroxyalkylamides, glycol.... triglycidyl isocyanurate, aliphathic polyoxciranes.uretdiones, blocked polyisocyanates, polyurethane resins, polyester- polyurethane resins, acrylate resins or mixtures of such resins. Also of interest are film- forming binders with thermoplastic properties, examples being polyethylene, polypropylene, polyamides, polyvinyl chloride, polyvinylidene dichloride or polyvinylidene difluoride. Further- more, powder coatings are also known which comprise ethylenically unsaturated components and can be cured with photoinitiators. Polyesters are in general hydroxy-functional or carboxy-functional and are commonly prepared by condensation of diols and dicarboxylic acids. By adding polyols and/or polyacids, branched polyesters are obtained which then, on stoving in the presence of crosslinking agents, give rise to network structures which give the coating the desired physical properties, such as scratch resistance, impact resistance and flexural strength. In place of polyfunctional acids it is also possible to use anhydrides or acid chlorides, for example maleic anhydride, itaconic anhydride, phthalic anhydride, terephthalic anhydride, hexahydroterephthaiic anhydride, trimellitic anhydride, pyromellitic dianhydride, succinic anhydride, etc. It is also possible to use simple esters, for example dimethyl terephthalate, in which case polymerization takes place by transesterification with elimination of the volatile alcohol. Likewise practicable is preparation by combination of transesterification and condensation. Furthermore, polyesters can be prepared by polycondensation of hydroxycarboxylic acids, for example 12-hydroxystearic acid and hydroxypivalic acid, or of the corresponding lactones, for example ε-caprolactone. Examples of dicarboxylic acids and polyacids include terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, 1 ,12-dodecanedioic acid, pyromellitic acid, 3,6-dichlorophthalic acid, succinic acid, 1 ,3-cyclohexanedicarboxylic acid and 1 ,4-cyclohexanedicarboxylic acid. Examples of diols and polyols include ethylene glycol, propylene glycol, glycerol, hexanetriol, hexane-2,5-diol, hexane-1 ,6-diol, pentaerythritol, sorbitol, neopentylglycol, trimethylolethane, trimethylolpropane, tris-1 ,4-cyclohexanedi- methanol, trimethylpentanediol, 2,2-diethyl-1 ,3-propanediol, 2-methyl-2-butyl-1 ,3-propane- diol, ester diol 204 (ester of hydroxypivalic acid and neopentylglycol), hydrogenated bis- phenol A, bisphenol A, hydroxypivalic acid, hydroxypivalate esters, 2-butyl-2-ethyl-1 ,3-propanediol, 1 ,4-butanediol, 2-butene-1 ,4-diol, 2-butyne-1 ,4-diol or 2-methyl-1 ,3-propanediol. Suitable crosslinking agents for carboxy-functional polyesters are epoxy compounds, such as, for example, novolak-epoxy resins, diglycidyl ethers of bisphenol A, hydrogenated bisphenol A, and bisphenol A modified by reaction with, for example, aliphatic dicarboxylic acids. Also suitable are reactive epoxy compounds, such as triglycidyltriazolidine-3,5-dione, the glycidyl esters of polyacids, for example diglycidyl terephthalate and diglycidyl hexa- hydroterephthalate, hydantoin epoxides (US-A-4 402 983) and, very particularly, triglycidyl isocyanurate and Araldit PT910 (Ciba-Geigy). Other crosslinking agents for carboxy-functional polyesters are β-hydroxyalkylamides (US-A-4 076 917), for example the predominantly tetrafunctional β-hydroxyalkylamide derivative of adipic acid (Primid XL552 from Rohm & Haas). Others which have proven suitable include derivatives of melamine, benzoguanimine and glycoluril, which are alkylated with low molecular weight alcohols. Examples are tetra- (R) methylmethoxyglycoluril (Powderlink 1174 from American Cyanamid). Other known cross- linking agents are bis- and trisoxazolidines, for example 1 ,4-bisoxazolidinobenzene. In comparison with systems crosslinked using tetramethylmethoxyglycoluril or β-hydroxyalkylamide derivatives of adipic acid, coatings containing triglycidyl isocyanurate as crosslinking agent are of greater corrosion resistance. The former systems tend to be less corrosion-resistant, which is possibly a result of the hydrophilicity of the crosslinking agent. In such systems, the compounds of the present invention are of particular interest as corrosion inhibitors. A recent development comprises carboxy-functional polyesters which contain chemically bonded epoxy groups and are consequently able to crosslink with themselves (Molhoek et al., 22nd Fatipec Congress, 15.-19.5.95, Budapest, Vol.1 , 119-132). In all systems in which an epoxy group or a glycidyl radical reacts with a carboxyl group or an anhydride in a crosslinking reaction, catalysts can be employed. Examples are amines or metal compounds, for example aluminium acetylacetonate or tin octoate. As crosslinking agents for hydroxyfunctional polyesters, the polyisocyanate crosslinkers are of particular importance. In order to prevent premature crosslinking because of the high reactivity of isocyanates, and in order to obtain good levelling of the melted powder, the polyisocyanates are blocked (internally as a uretdione or as an adduct with a blocking agent). The most frequently employed blocking agents are ε-caprolactam, methyl ethyl ketoxime or butanoneoxime. Other suitable blocking agents for isocyanates are described in the publications of G.B. Guise, G.N. Freeland and G.C. Smith, J. Applied Polymer Science, 23, 353 (1979) and of M.Bock and H.-U. Maier-Westhues in "Progress in Product Development for Powder Coating Technology", XIX th Int. Conf. on Organic Coatings, Science and Technol., Athens, 12-16 July, 1993. Examples of blocked or unblocked polyisocyanates include 2-methylpentane-1 ,5-diisocyanate, 2-ethylbutane-1,4-diisocyanate, 3(4)-isocyanato- methyl-1-methylcyclohexyl isocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexane diiso- cyanate, tris(isocyanatomethyl)benzene, 4,4'-diisocyanatodicyclohexylmethane, 1 ,4-bis- (isocyanatomethyl)cyclohexane, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate and, in particular, isophorone diisocyanate. For the purpose of deblocking, a metallic catalyst, for example tin octoate, dibutyltin oxide or dibutyltin dilaurate, is usually added to the polyisocyanate formulation. Other crosslinking agents suitable for hydroxy-functional polyesters are anhydrides, for example trimellitic anhydride and its reaction products with diols and diamines. Further examples of such crosslinking agents are described by T.A. Misev in "Powder Coatings: Chemistry and Technology", J.Wiley & Sons, Chichester on pages 123 and 124. Polyacrylates, which usually have hydroxy, carboxy or glycidyl functionality, are also employed as binders for powder coatings. They are prepared by the customary methods, predominantly from monomers such as styrene and linear or branched C-i-Cβalkyl esters of acrylic acid or methacrylic acid. Other ethylenically unsaturated compounds, for example divinylbenzene, acrylamide, methacrylamide, butoxymethylacrylamide, acrylonitrile, butadiene, etc., can also be added and copolymerized. Hydroxy functionality is provided by the copolymerization of hydroxy-functional monomers such as, for example, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate. For carboxy functionality, ethylenically unsaturated acids and anhydrides, for example acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, acrylic anhydride or methacrylic anhydride are used (US-A-3 836 604). Glycidyl functionality is provided, as taught in EP-A-0 256 369 and US-A-3 876 578, by the copolymerization of monomers such as glycidyl acrylate and glycidyl methacrylate. As crosslinking agents for polyacrylates with hydroxy or carboxy functionality it is in principle possible to use the same compounds as already described for the polyesters with hydroxy or carboxy functionality. Further suitable crosslinking agents are the epoxy compounds of US-A-0 045 040. Suitable crosslinking agents for polyacrylates with glycidyl functionality are dicarboxylic acids such as, for example, sebacic acid and 1 ,12-dodecanedioic acid, and anhydrides, for example bis- trimellitic anhydride and the compounds described in US-A-3 880 946. Also known, furthermore, are autocrosslinking polyacrylates, from DE-A-3 310 545. Epoxy resins for powder coatings are mostly either novolak-epoxy resins or, in particular, those based on aromatic polyols, especially on bisphenols such as bisphenol A. Also known are modified bisphenol-epoxy resins from JP-A-58 187 464 (1982). The epoxy resins are employed in combination with crosslinking agents from the classes of the solid aliphatic amines, solid aromatic amines, amine adducts, phenolic resins, polyacids and the already described carboxyfunctional polyesters. Hardeners (curing agents) meriting special mention are the dicyandiamides, which are frequently employed together with a catalyst such as, for example, Lewis acids, boron trifluoride amine complexes, metal complexes, tertiary or quaternary amines, and imidazoline derivatives such as 2-methylimidazoline. The powder coating compositions can in addition comprise one or more components from the group consisting of pigments, dyes, fillers, levelling assistants, degassing agents, charge control agents, optical brighteners, adhesion promoters, antioxidants, light stabilizers, curing catalysts and photoinitiators. They can also contain other known anticorrosion agents, for example anticorrosion pigments, such as phosphate- or borate-containing pigments or metal oxide pigments, or other organic or inorganic corrosion inhibitors, for example salts of nitroisophthalic acid, phosphoric esters, technical-grade amines or substituted benzotriazoles. Suitable photoinitiators are those based on benzophenones, phenyl glyoxalates, bis- or mono-acylphosphine oxides, α-hydroxy ketones or benzyl dimethyl ketals. The pigments are for example titanium dioxide, iron oxide, carbon black, aluminium bronze or phthalocyanine blue. Examples of fillers are talc, alumina, aluminium silicate, barytes, mica or silica. The corrosion inhibitors can also be applied to pulverulent carrier materials. Examples of degassing agents are fatty acid amides as described in EP-A-0471 409, ε-caprolactam, methyl isophthalate and dimethyl isophthalate (EP-A-284996), and especially benzoin. Examples of levelling assistants are epoxidized fatty acids, abietyl alcohol, polylauryl methacrylate, polylauryl acrylate, polydimethylsiloxane-polyalkylene oxide block copolymers or, in particular, low molecular weight copolymers and polymers of C-|-Cβalkyl acrylate esters or alkyl methacrylate esters. Adhesion promoters are based, for example, on modified silanes, titanates or zirconates. It is also advantageous to add basic fillers or pigments, which in certain binder systems bring about a synergistic effect on the inhibition of corrosion. Examples of such basic fillers and pigments are calcium carbonate or magnesium carbonate, zinc oxide, zinc carbonate, zinc phosphate, magnesium oxide, alumina, aluminium phosphate, or mixtures thereof. Examples of basic organic pigments are those based on aminoanthraquinone. In the case of the preparation of the organic film-forming binder by polymerization or poly- condensation of monomers the spiroindane compound (i) can be admixed to the monomers even prior to polymerization. The spriroindane compounds are expediently used in a quantity of from 0.05 to 10% by weight, preferably from 0.1 to 10% by weight, in particular from 0.1 to 2% by weight, based on the weight of the total solids of the powder coating composition. In addition to the already mentioned phosphites further conventional additives may be present in the paint compositions. Examples of conventional additives are: UV absorbers and light stabilisers 1. 2-(2'-Hydroxyphenyl)benzotriazoles. for example 2-(2'-hydroxy-5'-methylphenyl)-benzo- triazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxy- phenyl)benzotriazole, 2-(2'-hydroxy-5'-(1 ,1 ,3,3-tetramethylbutyl)phenyl)benzotriazole, 2- (3',5'-di-tert-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)benzo- triazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxy- phenyl)benzotriazole, 2-(3',5'-bis(a,a-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, mixture of 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylhexyloxy)-carbonylethyl]-2'-hydroxyphenyl)-5-chloro-benzotri- azole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 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-ethyl- hexyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methyl- phenyl)benzotriazole, and 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenyl- benzotriazole, 2,2'-methylene-bis[4-(1 ,1 ,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol]; the transesterifica tion product of 2-[3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxy- phenyl]-2H-benzotriazole with polyethylene glyco!300; where R = 3'-tert-butyl-4'-hydroxy-5'-2H-benzotriazol-2-ylphenyl. 2.2-Hvdroxybenzophenones. for example the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives. 3. Esters of substituted and unsubstituted benzoic acids, as for example 4-tert-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-tert-butyl- 4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyI 3,5-di-tert-butyl-4-hydroxybenzoate. 4. Acrylates. for example ethyl a-cyano-b,b-diphenylacrylate, isooctyl a-cyano-b,b- diphenylacrylate, methyl a-carbomethoxycinnamate, methyl a-cyano-b-methyl-p-methoxy- cinnamate, butyl a-cyano-b-methyl-p-methoxy-cinnamate, methyl a-carbσmethoxy-p- methoxycinnamate and N-(b-carbomethoxy-b-cyanovinyl)-2-methylindoline. 5. Nickel compounds, for example nickel complexes of 2,2'-thio-bis[4-(1 ,1 ,3,3-tetra- methylbutyl)phenol], such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarba- mate, 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-methyl- phenyl undecylketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands. 6. Stericallv hindered amines, for example bis(2,2,6,6-tetramethylpiperidyl)sebacate, bis- (2,2,6,6-tetramethylpiperidyl)succinate, bis(1 ,2,2,6,6-pentamethylpiperidyl)sebacate, bis- (1 ,2,2,6,6-pentamethylpiperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert- octylamino-2,6-dichloro-1 ,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1 ,2,3,4-butane-tetracarboxylate, 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, bis(1 ,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2- hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]- decan-2,4-dion, 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 2- chloro-4,6-bis(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-n-butylamino-1 ,2,2,6,6- pentamethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis(3-aminopropylamino)ethane, 8-acetyl-3-do- decyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetra- methyl-4-piperidyl)pyrrolidin-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrro- lidine-2,5-dione. 7. Oxamides. for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-- 5,5'-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'-ethoxyanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide and mixtures of ortho- and para- methoxy-disubstituted oxanilides and mixtures of o- and p-ethoxy-disubstituted oxanilides. 8. 2-(2-Hvdroxyphenyl)-1.3.5-triazines. for example 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)- 1 ,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2- (2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2,4-bis(2-hydroxy-4-propyl- oxyphenyl)-6-(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(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-butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)- 1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bis(2,4-dimethyl)- 1 ,3,5-triazine. 3. Metal deactivators. for example N.N'-diphenyloxamide, N-salicylal-N'-salicyloyl hydrazine, N,N'-bis(salicyloyl) hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) 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 dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide. 4. Phosphites and phosohonites. 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, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tris(tert- butylpheny pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-bu- tylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-di- benz[d,g]-1 ,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenz[d,g]- 1 ,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methylphenyl)methylphosphite, bis(2,4-di-tert- butyl-6-methylphenyl)ethyl phosphite . 5. Peroxide scavengers, for example esters of b-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or the zinc salt of 2-mercapto- benzimidazole, zinc dibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritol tetrakis - dodecylmercapto)propionate. 6. Polyamide stabilisers, for example, copper salts in combination with iodides and or phosphorus compounds and salts of divalent manganese. 7. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids for example calcium stearate, zinc stearate, magnesium behenate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or tin pyrocatecholate. 8. Nucleating agents, for example, 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid. 9. Fillers and reinforcing agents, for example, calcium carbonate, silicates, glass fibres, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite. 10. Other additives, for example, plasticisers, lubricants, waxes, slip agents, emulsifiers, pigments, optical brighteners, flameproofing agents, antistatic agents, biocides and blowing agents. The following Applications Examples will illustrate the invention without limiting the scope thereof. Example 1 : A typical epoxy/polyester powder coating composition was made up, but for ease of handling was dissolved in solvent and coated from solution. The polyester was a commercially available carboxy-functionalised type, having an acid value of 70 - 85 and was free from added antioxidants. The powder coating components were dissolved up in the solvent mix using a high speed dissolver. 35 g portions of the coating liquid were added to 0.0467g of the additives to be tested in a screw-cap bottle. The contents were dissolved up, degassed under vacuum and the weight readjusted with fresh dichloromethane before coating at 150 m wet coating weight onto coil-coated aluminium. The coatings, after drying, were all of thickness 51 .3 μm and contained a total of 0.5% additives (on resin). To cure the coatings, a gas reactor was used. The gas reactor is a flat plate of thermally- annealed stainless steel (to avoid distortion on heating) having a shallow cavity in the middle Araldit GT 7004 Is a solid bisphenol A-based epoxy resin of medium molecular weight and an epoxy index of 1.33 - 1.40 Eq. kg, available from Ciba-Geigy AG, CH-4002 Basel, Switzerland. 2 Resiflow PV88 is a liquid polyacrylate flow aid absorbed on a silica support, available from Wortee-Chemie GmbH, D-21481 Lauenburg, Germany. 3 Fluorad FC-170C is a nonionic fluorinated al ylpolyoxyethylenethanol, available from 3M Deutschland GmbH, D-4040 Neuss, Germany. and sealed by a heavy, removable stainless steel lid. At one end, a preheated mixture of approximately 80 ppm NO2 in air was passed into the block, flowed both over and under the test samples and was allowed to escape at the other end. The gas reactor was placed in an electric ovenset at 200°C, on a thermally insulating support. The coatings were cured for 15 mins. and overbaked for 15 minutes using this simple apparatus. After curing and overbaking the yellowness index was measured using a Macbeth colour analyser. A high value of the yellowness index denotes greater yellowness of the test panel. The followin results were obtained: Example 2: In order to demonstrate that the compounds of the invention are effective in a typical epoxy/polyester powder coating, the following formulations were mixed together in a planetary mixer. Crylcoat 360 Is a carboxy-functional polyester resin from UCB SA. B-1620 Drogenbos, Belgium with an add value (mg KOH g) of 50. The formulations were extruded twice using a Buss PLK46L cokneader at 40 and 80°C in zones 1 and 2 respectively and 125 rpm. The extrudate was cooled, crushed, milled in a Retsch ZM-1 ultracentrifugal mill at speed setting 2 with a 0.75 mm sieve and finally sieved g through a 125 m"10 gyratory sieve. The resultant powder had a mean particle size of 32 m * 10 -6 The powder paint was applied to white coil-coated aluminium panels with an ESB- Wagner Airmatic Corona-Star type PEM-CG1 gun (with a low output of free electrons) to give coatings of thickness ca. 120 rτrl0 . The powder was not cured, but briefly fused by a heat treatment of 30 seconds at 160°C in air. Samples of the coatings were cured by heating 15 mins at 195°C in pure air and in the previously-described gas reactor in an air/80 ppm NO2 mixture. The yellowness index was measured using a Macbeth colour analyser after fusing the powder and after baking: from these values the yellowness index differences were calculated. The following results were obtained: It can be seen that the state-of-the-art stabilisers give unsatisfactory yellowing as soon as traces of nitrogen oxides are present and that the compounds of the invention give better stabilisation, ie. smaller increments in the yellowness index.

Claims: PATENT CLAIMS 1. A composition comprising (A) a paint or coating material (B) at least one compound of formula Rl .R2. R3 and R4 are independently of one another: a) unsubstituted C1-C1 βalkyi or C1-C1 βalkyi substituted by one or more of the groups OH, C -C-|βalkoxy, C2-C1 βalkenyloxy, halogen, phenoxy (which is unsubstituted or substituted by Cι-Ci8alkyl, Cι-Cιβalkoxy or halogen), -COORβ, -CONH2, - CONHRgor -CONRgRio; b) C5-C 2cycloalkyl which is unsubstituted or substituted by OH or -OCOR * | 1 ; c) a five or six-membered heterocycle that is saturated or unsaturated; d) C7-C11 phenylalkyl, which is unsubstituted or substituted by one or more OH, CI or CH 3; e) C2-C1 βalkenyl; f) C4-C30 alkyl which is interrupted by one or more O atoms and can be substituted by OH; g) -CO-R12 or -(CH2) n-CO-Ri2 ; h) -SO2-R13; i) a group i) a group k) a group n is an integer between 1 and 18; R5 is H, C-|-Ci8 straight chain or branched alkyl, C2-Cιβalkenyl or C6-C-|2aryl; Rβ and R7 are independently of one another H, halogen, Cι-Cιβalkyl, C2-C6alkβnyl, Cι-Ci2alkoxy or C2-Ci2alkenyloxy; Rβ is C1-C1 βalkyi. C2-C1 βalkenyl, C3-C20 alkyl which is interrupted by one or more O, NRg or S and /or substituted by OH, C * | -Chalky I which is substituted by -P(0)(ORιβ)2. C3-Cβalkynyl or C7-C11 phenylalkyl; Rg and R10 are independently of one another Cι-Ci2alkyl, C3-Ci2alkoxyalkyl, C4- Ciβdialkylaminoalkyl or C5-Ci2cycloalkyl, or Rg and R10 together are C3- Cgalkylene or C3-Cgoxaalkylene or C3-Cgazaalkylene; R-| 1 is C1-C1 βalkyi, C2-C1 βalkenyl or phenyl; R-J2 is C1-C1 βalkyi, C2-Cιβalkenyl, phenyl, Cι-Ci2alkoxy, phenoxy, C-|- C * | 2alkylamino or Cβ-Ci 2arylamino or a group -R1 g-COOH; R13 is Cι-Ci2alkyl, C6-Ci2aryl or C7-Ci4alkylphenyl; R 4 is hydrogen, oxyl, hydroxy, -CH2CN, C1-C1 βalkyi, C-j-Ciβ- alkoxy, C3- Cβalkenyl, C3-Cβalkynyl, Cs-CβcycloalkyI or -alkoxy, phenyl, naphthyl, C7- C 2phenylalkyl or -alkoxy, phenyl or phenylalkyl substituted by alkyl or phenyl of 7- 14 carbon atoms, C3-C5alkenoyl, C * ι -C βalkynoyloxy, benzyloxy or a group CH2- CH(OH)-Z where z is H, CH3 or Phenyl, or a group of the formula || wherein D' is Ci -Ci βalkyi, Ci - Ciβalkoxy, phenyl, or phenyl substituted by hydroxy, C-i-Cβalkyl, Ci-Cβalkoxy, amino or amino mono- or disubstituted by C -Cβalkyl or phenyl. θ/ R-|5 is H, C-j-C-i βalkyi or C3-C1 βalkyi interrupted by one or more oxygen atoms; cyanoethyl, benzyl, glycidyl, a monovalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acid, or of carbamic acid, or of a phosphorus- containing acid, or a monovalent silyl radical -Si(R2l)(R22)(R23) ; R * l6 is H, -CO-R-11, -Si(R2l)(R22)(R23) . or -COOR24; R-I7 is C1-C18 alkyl, C2-C18 alkenyl, phenyl-C * |-C4alkyl, C3-C24alkyl or C2- C-|4hydroxyalkyl, each of which is interrupted by one or more O atoms, or is phenyl, which is unsubstituted or substituted by C * ι -C4alkyl, C * |-C4alkoxy or halogen, C5- C-| 2cycloalkyl which is unsubstituted or substituted by 1 - 3 Ci-Cβ alkyl, or -COR11 , or R18 is C1-C1 βalkyi or phenyl ; R-|g is Cι-Cιβalkylene, vinylene or phenylene; R20 is H, OH, oxyl, Cι-Cιβalkyl. C2-C1 βalkenyl, C * |-Cιβalkoxy, C5-C 2cycloalkyl, Cδ-Ci2cycloalkoxy, C3-Cβalkynyl, C7-Ci2Phenylalkyl, C-j-Cβalkanoyl, C3- Csalkenoyl or glycidyl; R21. R22 and R23 are independently of one another Ci-Cβalkyl or phenyl; and R24 is C-|-C4alkyl. 2. A composition according to claim 1 wherein in formula I R5 is H; Rl ,R2. R3 and R4 are the same and can be a) Ci -C*ι β straight chain or branched alkyl, optionally substituted by one or more of the groups OH, Cι-Cιβalkoxy, C2-Cιβalkenyloxy, -COORβ, -CONH2, - CONHRg, -CONRgR-io; b) C5-C12cycloalkyl which is unsubstituted or substituted by OH or -OCOR11 ; c) tetrahydropyran; e) C2-C1 βalkenyl; f) C4-C30 alkyl which is interrupted by one or more O atoms and can be substituted by OH; g) -CO-R12 or -(CH2) n-CO-R * | ; i) a group j) a group k) a group n is 1 to 18; Rβ and R7 are independently of one another H or Ci-Cβalkyl; Rβ is C1-C1 βalkyi, C2-C1 βalkenyl, C3-C20 alkyl which is interrupted by one or more O or substituted by OH or is C3-Cβalkynyl; Rg and R10 are independently of one another Cι-Ci2alkyl, C3-Ci2alkoxyalkyl or C5- Ci2cycloalkyl; R11 is C1-C1 βalkyi or C2-Cιβalkenyl; R12 is C1 -C1 βalkyi, C2-C1 βalkenyl, Cι-Ci2alkoxy, Cι-C 2alkylamino or a group - Rig-COOH, 14 R is especially C -Ci2alkyl, allyl, cyclohexyl, benzyl, acβtyl, acryloyl, Cyclohexyloxy or Cι-C 2-alkyoxy R15 is H or C -C1 βalkyi optionally interrupted by one or more oxygen atoms; Rlβ is H, -CO-R11, -Si(R2l)(R22)(R23) . or -COOR24; R17 is C1 -C18 alkyl, C2-C 8 alkenyl, C3-C24alkyl or C2-Ci4hydroxyalkyl, each of which is interrupted by one or more O atoms, C5-Ci2cycloalkyl which is unsubstituted or substituted by 1 - 3 Ci-Cβ alkyl, or -COR11 , or Ri is C -Cιβalkylene or vinylene; R20 is H, OH, oxyl, C1-C1 βalkyi, C2-C1 βalkenyl, Cι-Cιβalkoxy, C5-Ci2cycloalkyl, C5- Ci2cycloalkoxy, C3-Cβalkynyl, Ci-Cβalkanoyl, C3-C5alkenoyl or glycidyl; R21. 22 and R23 are independently of one another Ci-Cβalkyl; R24 is Cι-C4alkyl. 3. A composition according to claim 1 wherein in formula I R5, Re and R7 are H; Rl ,R2. 3 and R4 are the same and can be either: a) C -Ci β straight chain or branched alkyl; b) cyclohexyl ; e) allyl; f) C3-C12 alkyl which is interrupted by one or more O atoms; g) -CO-R12; i) a group j) a group k) a group n is 1 to 6; R12 is Cι-C4alkyl or C2-C3alkenyl; R14 is Cι-Ci2alkyl, benzyl, or Cδ-Cβcycloalkyl; most preferably C6-Cifjalkyl or cyclohexyl. R is H or C1-C1 βalkyi optionally interrupted by one or more oxygen atoms Rl6 is H, -CO-R11 or -COOR24; R17 is C1-C18 alkyl, C2-C18 alkenyl, C3-C24alkyl or C2-Ci4hydroxyalkyl, each of which is interrupted by one or more O atoms or is Cδ-Ci2cycloalkyl; or is R20 is H, Ci-Cβalkyl, acetyl, propargyl, acryloyl, Ci-Cβalkoxy or Cδ-Ci2cycloalkyl; R24 is Ci -C4alkyl. 4. A composition according to claim 8 wherein the paint or coating material is a powder coating. 5. A composition according to claim 1 which contains at least one additional phosphite stabilizer. 6. A composition according to claim 10 wherein the phosphite stabilizer is of fomula or is tris- (2,4-di-tert-butylphenyl)-phosphite. 7. A composition according to claim 10 which contains at least one additional phenolic antioxidant. 8. A composition according to claim 8 wherein the spiroindane compound is present in a quantity of from 0.05 to 10% by weight, based on the weight of the total solids of the powder coating composition. 9. A process for stabilizing a coating material or paint which comprises adding thereto an effective stabilizing amount of a compound of the formula I as described in claim 1. 10. A compound of formula I as described in claim 1 , with the proviso that at least one of R1 to R4 is a group i), j) or k) wherein R17 is a group

Inventors: LAVER HUGH STEPHEN, LAVER, HUGH, STEPHEN
Applicants: CIBA GEIGY AG, LAVER HUGH STEPHEN, CIBA SPECIALTY CHEMICALS HOLDING INC., LAVER, HUGH, STEPHEN
Application year: 1997
Main classification: C09D7
IPC codes: C07D211, C09D7