Drier for auto-oxidisable coating compositions

Abstract

A drier for air-drying an auto-oxidizable resin composition, said drier comprising: 1,4,7-trialkyl-1,4,7-triazacyclononane (L); a manganese salt having the general formula Mn.sup.2+[X].sub.n, wherein anion X is selected from PF.sub.6.sup., SbF.sub.6.sup., AsF.sub.6.sup., BF.sub.4.sup., B(C.sub.6F.sub.5).sub.4.sup., Cl.sup., Br.sup., I.sup., NO.sub.3, or R.sub.2COO.sup. in which case n=2, or the anion X is SO.sub.4.sup.2 in which case n=1, and wherein R.sub.2 is C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, C.sub.6-C.sub.20) aryl optionally substituted with heteroatoms, or a polymeric residue; wherein the 1,4,7-trialkyl-1,4,7-triazacyclononane (L) is present in the mixture in an amount such that the molar ratio of Mn:L is at least 1.25:1 and preferably at least 1.5:1.

Claims

1. A drier composition for air-drying auto-oxidizable resin compositions, the drier composition comprising: a) a manganese salt having the general formula Mn.sup.2+[X].sub.n, wherein anion X is selected from the group consisting of PF.sub.6.sup., SbF.sub.6.sup., AsF.sub.6.sup., BF.sub.4.sup., B(C.sub.6F.sub.5).sub.4.sup., Cl.sup., Br.sup., I.sup., N0.sub.3.sup., and R.sub.2COO.sup. in which case n=2, or the anion X is SO.sub.4.sup.2 in which case n=1, and wherein R.sub.2 is C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, C.sub.6-C.sub.20 aryl optionally substituted with heteroatoms, or a polymeric residue; and b) 1,4,7-trisubstituted-1,4,7-triazacyclononane (L) wherein said 1,4,7-trisubstituted-1,4,7-triazacyclononane (L) has the general structure ##STR00004## wherein R.sub.1 is C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, or C.sub.6-C.sub.20 aryl optionally substituted with heteroatoms; and wherein the molar ratio of Mn:L is at least 1.25:1.

2. The drier composition according to claim 1, wherein R.sub.1 is a C.sub.1-C.sub.6 alkyl.

3. The drier composition according to claim 1, wherein n=2 and anion X is R.sub.2COO.sup..

4. The drier composition according to claim 3, wherein R.sub.2 is a C.sub.1-C.sub.20 alkyl group, wherein the alkyl group is a straight or branched chain, saturated or unsaturated.

5. The drier composition according to claim 1, wherein the molar ratio of Mn:L is lower than 20:1.

6. An air-drying auto-oxidizable resin composition comprising: a) the drier according to claim 1; and b) a polymer comprising unsaturated aliphatic groups.

7. The resin composition according to claim 6, wherein the resin composition is selected from the group consisting of alkyds, vinyl polymers, polyurethane resins, hyperbranched resins and mixtures thereof.

8. The resin composition according to claim 7, wherein the resin composition is an alkyd.

9. A coating composition comprising the resin composition according to claim 6.

10. The coating composition according to claim 9, further comprising one or more auxiliary and/or coordination driers in an amount not exceeding 10 wt %.

11. A method of coating a substrate comprising, applying the coating composition according to claim 10 onto the substrate; and drying the coating composition in the presence of air.

12. The method according to claim 11, wherein the drying occurs at ambient temperature.

13. A coated substrate comprising a substrate coated with the coating composition according to claim 9.

14. A liquid comprising the resin composition according to claim 7, wherein the liquid is selected from the group consisting of a paint, an adhesive, a lacquer, an ink and a varnish.

15. A method of drying comprising air-drying an auto-oxidizable resin composition according to claim 6.

16. The method according to claim 15, wherein the 1,4,7-trisubstituted-1,4,7-triazacyclononane (L) is present in an amount such that the molar ratio of Mn:L is at least 1.5:1.

17. The drier composition according to claim 1, wherein the 1,4,7-trisubstituted-1,4,7-triazacyclononane (L) is provided in an amount such that the molar ratio of Mn:L is at least 1.5:1.

18. The drier composition according to claim 1, wherein R.sub.1 is a methyl.

19. The drier composition according to claim 3, wherein R.sub.2 is a C.sub.4-C.sub.12 alkyl group, wherein the alkyl group is a straight or branched chain, saturated or unsaturated.

20. The drier composition according to claim 1, wherein the molar ratio of Mn:L is lower than 10:1.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The Drier

(2) 1,4,7-trialkyl-1,4,7-triazacyclononane (L) is a polydentate ligand having following general structure:

(3) ##STR00003##

(4) By polydentate is meant that the ligand contains multiple donor atoms available for coordination with manganese. Herein R.sub.1 is C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, or C.sub.6-C.sub.20 aryl optionally substituted with heteroatoms. Preferably R.sub.1 is a C.sub.1-C.sub.6 alkyl, and more preferably R.sub.1 is methyl such that specifically L is 1,4,7-trimethyl-1,4,7-triazacyclononane (TMTACN).

(5) As defined above, the manganese salt from which the drier is derived has the general formula Mn.sup.2+[X].sub.n, wherein anion X is selected from PF.sub.6.sup., SbF.sub.6.sup., AsF.sub.6.sup., BF.sub.4.sup., B(C.sub.6F.sub.5).sub.4.sup., Cl.sup., Br.sup., I.sup., NO.sub.3.sup., or R.sub.2COO.sup. in which case n=2, or the anion X is SO.sub.4.sup.2 in which case n=1, and wherein R.sub.2 is C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, C.sub.6-C.sub.20 aryl optionally substituted with heteroatoms, or a polymeric residue. In a preferred embodiment, the drier is derived from a manganese carboxylate starting material, that is the anion is R.sub.2COO.sup.. The preparation of transition metal salts of organic carboxylic acids is described inter alia in U.S. Pat. No. 4,633,001 (Cells) and U.S. Pat. No. 4,824,611 (Cells), the disclosures of which patents are herein incorporated by reference.

(6) As described above R.sub.2 may be C.sub.1-C.sub.20 alkyl optionally substituted with heteroatoms, C.sub.6-C.sub.20 aryl optionally substituted with heteroatoms, or a polymeric residue. Preferably R.sub.2 is a C.sub.1-C.sub.20 alkyl group, wherein the alkyl group is straight or branched chain, saturated or unsaturated.

(7) The aliphatic chain, including the branching group(s), in the acids of the manganese carboxylates may contain, or be substituted by, one or more atoms or groups which are inert under the conditions to which the carboxylates are subjected during processing and use. However, it is preferred that the aliphatic chain, including any branching group(s), is made up of carbon and hydrogen atoms only. Furthermore, the aliphatic chain, including any branching group(s), is preferably saturated.

(8) Most preferably R.sub.2 is a C.sub.4-C.sub.12, branched or straight chain, saturated aliphatic group. Specific examples of such carboxylate anions include: 4-methylpentanoate; 5-methylhexanoate; 2-ethylhexanoate; 3-ethylhexanoate; 3,5-dimethylhexanoate; 4,5-dimethylhexanoate; 3,4-dimethylhexanoate; 3,5,5-trimethylhexanoate; 4-methylheptanoate; 5-methylheptanoate; 6-methylheptanoate; 4,6-dimethylheptanoate; 7-methyloctanoate; 8-methylnonanoate; and, 9-methyldecanoate.

(9) The drier may be prepared by mixing together the manganese salt and the ligand (L), one or both components being dispersed in an appropriate liquid medium. The ligand (L) may, for example, be dispersed in an organic solvent or a mixture thereof such as a 10% solution of trimethyl triazacyclonane in methoxy proponal (25%) and Shellsol D40 (65%). The ligand can be bought e.g. at Sigma-Alldrich. The ligand can be used as such.

(10) It is also envisaged that the drier may be formed in situ within the auto-oxidizable resin composition: a resin composition may be provided in which the manganese salt has been premixed; the ligand (L) is then mixed into the resin composition in an amount such that the molar ratio of Mn:L is at least 1.25:1 for example 1.5:1.

(11) It is furthermore envisaged that the drier is prepared by mixing a binuclear tricarboxy-bridged manganese-L complex and an additional amount of manganese compound in a coating composition.

(12) These mixing processes involve physical mixing only. This physical process can thereby be distinguished from the chemical reaction conditions employed in K. Wieghardt et al. J. Am. Chem. Soc. 110, 7398-7411 (1998) which necessarily entail the use of perchloric acid and sodium hyperchlorate as reactants. Equally, a reaction with hydrogen peroxide as described in WO2011/106906 is not necessary. The present invention thereby provides for a simpler and more economical preparation of the drier. The drier may of course be manufactured by more elaborate methods, including for example chemical reactions.

(13) Auto-oxidizable Drying Resin Composition

(14) In general, the oxidatively drying resin may be selected from alkyds, vinyl polymers, polyurethane resins, hyperbranched resins and mixtures thereof. The driers of the present invention are however considered to have particular utility for alkyd resins.

(15) The number average molecular weight (Mn) of the oxidatively drying resin will generally be above 150, more usually higher than 1,000 and most typically higher than 5,000. For reasons of viscosity, the number average molecular weight (Mn) should generally be below 120,000, and more usually below 80,000.

(16) The amount of unsaturated fatty acid residues in the oxidatively drying resin will depend on the polymer type. However, preferably the resin will comprise 20 wt %, more preferably 50 wt %, and most preferably 75 wt % of unsaturated fatty acid residues based on the total solids content of the resin.

(17) Suitable drying unsaturated fatty acids, semi-drying fatty acids or mixture thereof, useful herein for providing the fatty acid groups in the resin include ethylenically unsaturated conjugated or non-conjugated C2-C24 carboxylic acids, such as myristoleic, palmitoleic, arachidonic, erucic, gadoleic, clupanadonic, oleic, ricinoleic, linoleic, linolenic, licanic, nisinic acid and eleostearic acids or mixture thereof, typically used in the form of mixtures of fatty acids derived from natural or synthetic oils. Suitable unsaturated fatty acids for providing fatty acid groups in the resin also include fatty acids derived from soybean oil, conjugated soybean oil, palm oil, linseed oil, tung oil, rapeseed oil, sunflower oil, conjugated sunflower oil, calendula oil, wood oil, tallow oil, (dehydrated) castor oil, safflower oil, tuna fish oil, coconut oil and dehydrated coconut oil, and combinations thereof. Whilst the main crosslinking mechanism of the composition of the present invention is by auto-oxidation, other crosslinking mechanisms may supplement this to give dual (or multiple) curing. Such secondary curing mechanisms may result from providing the unsaturated fatty acid functionalized polymer with additional functional groupssuch as vinyl and carbonyl groupsthat may provide further crosslinking, resulting in an even faster drying process of the coating composition. A person of ordinary skill in the art would be aware of a number of suitable, secondary crosslinking groups, which may of course be blocked or unblocked.

(18) Such functional groups may be introduced into the auto-oxidisable resin using two general methods: i) by utilising monomers carrying the functional group in the polymerisation process used to form the auto-oxidisable resin; or ii) utilising monomers bearing selected reactive groups and which monomer is subsequently reacted with a compound carrying the functional group and also a reactive group of the type which will react with the selected reactive groups on the monomer to provide attachment of the functional group to the auto-oxidisable resin via covalent bonding.

(19) However, the presence of such groups should be selected such that the most significant part of any crosslinking reaction(s) only takes place after application of the resin to a substrate. This will avoid an in-can build-up of the molecular weight of the resins which may be problematic where the viscosity of the resin composition either becomes too high for application or becomes too high for effective leveling of the composition upon its application to a substrate or in the early stages of drying.

(20) The auto-oxidative curing of the composition preferably takes place at ambient temperature, said temperature being herein from 0 to 40 C., preferably from 5 to 30 C. and most preferably from 10 to 25 C.

(21) It is envisaged that the oxidatively drying resin may be used in combination with other resins, for example acrylic resins or polyurethanes. Any such mixed binder system should preferably comprise at least 60 wt. % of oxidatively drying resin, based on total resin.

(22) Vinyl Polymers

(23) By vinyl polymer herein is meant a polymer derived from ethylenically unsaturated monomers. (Poly)acrylates, also known as acrylics, are polymers derived from monomers which comprise alkyl esters of (meth) acrylic acid. The vinyl auto-oxidisable polymer is preferably prepared by free radical polymerization of vinyl monomers using a suitable initiator. Examples of vinyl monomers include: 1,3-butadiene, isoprene, styrene, -methyl styrene, divinyl benzene, (meth)acrylonitrile, vinyl halides, vinylidene halides, vinyl ethers, vinyl esters, heterocyclic vinyl compounds, alkyl esters of mono-olefinically unsaturated dicarboxylic acids, and, in particular, C.sub.1 to C.sub.20 alkyl esters of (meth)acrylic acid. Of these, particularly preferred monomers include butyl (meth)acrylate, methyl (meth)acrylate methyl methacrylate, ethyl hexyl methacrylate, acrylonitrile, vinyl acetate and styrene.

(24) Monomers which are useful for grafting the fatty acid onto the vinyl polymer to give fatty acid residues include hydroxylalkyl(meth)acrylates, such as hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate and epoxy functional vinyl monomers like glycidyl(meth)acrylate (GMA) or 3,4-epoxy-cyclohexylmethyl-acrylate. The incorporation of unsaturated fatty acid groups into vinyl polymers in also described inter alia in: U.S. Pat. Nos. 7,235,603; 6,599,972; 6,624,223; 3,988,273; and, WO2007/042684. The vinyl monomers may optionally contain functional groups which can contribute to the crosslinking of the vinyl polymer(s) in the coating. Examples of such groups include maleic, epoxy, fumaric, acetoacetoxy, -diketone, unsaturated fatty acid, acryloyl, methacrylol, styrenic, (meth)allyl groups, mercapto groups, keto or aldehyde groups (such as methylvinylketone, diacetoneacrylamide and (meth)acrolein).

(25) Preferably the acid value of the vinyl polymer is from 0 to 60 mg KOH/g polymer, more preferably from 10 to 45 mg KOH/g and most preferably from 15 to 35 mg KOH/g polymer.

(26) Hyperbranched Resins

(27) WO 2007/147559, herein incorporated by reference, describes water soluble unsaturated fatty acid functional hyperbranched polyamides suitable for use in the present invention. The hyperbranched polyamide resin preferably has an amide (NHC=0 or NC=0) group content of <500 mmoles/100 g solid amide group containing resin, more preferably <400 mmoles/100 g and most preferably <300 mmoles/100 g solid amide group containing resin.

(28) Hyperbranched polyesteramide resins, which may also find utility in the present invention, are polymers having branched structure with a high functionality obtained by the polycondensation of, for example, an anhydride with an alkanol-amine. Such resins and their methods of production are described in WO 99/16810, the disclosure of which is herein incorporated by reference. Broadly, the polyesteramide is prepared from three components, at least one anhydride, at least one alkanol-amine and at least one unsaturated fatty acid to impart the air-drying property. The alkanol-amine may be a monoalkanol-amine, a dialkanol-amine, a trialkanol-amine or a mixture thereof: to form highly branched structures, di- and trialkanol-amines should be used, in which regard diisopropanolamine (DIPA) may be mentioned as a preferred example.

(29) Further hyperbranched polymers are described in: US Patent Application Publication No. 20090191412 (Van Benthem et al.); U.S. Pat. No. 5,731,095; EP 1440107 A1; Tomalia et al. Angewandte Chemie International (Edition English) 1990, Vol. 29, pp. 138-175; and, Encyclopaedia of Polymer Science and Engineering, Volume Index 1990, pp. 46-92.

(30) Polyurethane Resins

(31) Polyurethane polymers generally contain urethane groups (NHCOO) or urea groups (CO(NH).sub.2) in their backbone structure. They are typically formed by the reaction of a polyisocyanate with a polyol and polyamines. Auto-oxidisable aqueous polyurethane dispersions are obtainable by reacting drying and/or semidrying oils with low molecular weight polyhydroxy compounds to yield compounds which contain on average at least one hydroxyl group and at least one residue of a fatty acid having at least one CC double bond; these compounds are then reacted together with polyols, with compounds which have at least two isocyanate-reactive groups and at least one acid group or at least one group which, after neutralisation, forms a cationic group, like, for example, an ammonium group, with polyfunctional isocyanates. If desired, the prepolymer is then reacted with a compound which has an isocyanate-reactive group, followed by neutralizing the product formed with tertiary amines or mono-functional acids and transferring the utilized product to the aqueous phase, and subsequently, if desired, reacting any excess isocyanate groups still present by adding chain extenders, which have at least two primary or secondary amino groups or hydrazine groups per molecule.

(32) Suitable isocyanates used as building blocks for the auto-oxidisable polyurethane resin are for example diisocyanates, such as 1,6-hexane diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl diisocyanate, and dicyclo-hexylmethane diisocyanate. Triisocyanates can also be used.

(33) Alkyds

(34) By alkyd resin herein is meant a resin prepared from the reaction of a polyhydric alcohol, a polybasic acid and an unsaturated oil or fatty acid to give an unsaturated fatty acid residue containing ester. The unsaturation in the ester polyol imparts latent cross-linkability upon auto-oxidation so that when a coating composition thereof is dried in the air, in conjunction with the drier salt, the coating material undergoes cross-linking (by auto-oxidation) and thereby improving its properties, for example its chemical resistance, hardness and/or durability.

(35) The term alkyd resin is also meant to include such modified alkyds for specific applications, such as silicon-based alkyds, thixotropic alkyds and, most importantly, urethane-modified alkyds. As such, the alkyd resin may be based on pure polyester resin (not having urethane and/or amide groups), polyesteramide resin, urethanised polyester resin, urethanised polyesteramide resin and mixtures thereof.

(36) Examples of suitable divalent polyol compounds are ethylene glycol, 1,3-propane diol, 1,6-hexane diol, 1,12-dodecane diol, 3-methyl-1,5-pentane diol, 2,2,4-trimethyl-1,6-hexane diol, 2,2-dimethyl-1,3-propane diol, and 2-methyl-2-cyclohexyl-1,3-propane diol. Examples of suitable triols are glycerol, trimethylol ethane, and trimethylol propane. Suitable polyols having more than 3 hydroxyl groups are pentaerythritol, sorbitol, and etherification products of the compounds in question, such as ditrimethylol propane and di-, tri-, and tetrapentaerythritol. Optionally, use is made of compounds having 3-12 carbon atoms, e.g., glycerol, pentaerythritol and/or dipentaerythritol.

(37) Alternatively or additionally, polycarboxylic acids can be used as building blocks for the oxidatively drying polyunsaturated condensation products. Examples of suitable polycarboxylic acids include phthalic acid, citric acid, fumaric acid, mesaconic acid, maleic acid, citraconic acid, isophthalic acid, terephthalic acid, 5-tert. butyl isophthalic acid, trimellitic acid, pyromellitic acid, succinic acid, adipic acid, 2,2,4-trimethyl adipic acid, azelaic acid, sebacic acid, dimerized fatty acids, cyclopentane-1,2-dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, 4-methylcyclohexane-1,2-dicarboxylic acid, tetrahydrophthalic acid, endomethylene-cyclohexane-1,2-dicarboxylic acid, butane-1,2,3,4-tetra-carboxylic acid, endoisopropylidene-cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, and butane-1,2,3,4-tetracarboxylic acid. If so desired, the carboxylic acids in question may be used as anhydrides or in the form of an ester, e.g., an ester of an alcohol having 1-4 carbon atoms.

(38) At least a part of the alkyd resin is oxidatively crosslinkable as a result of the incorporation of unsaturated, aliphatic compounds as described above. Fatty acids containing conjugated double bonds, such as dehydrated castor oil fatty acid, wood oil fatty acid and/or calendula oil fatty acid, may be mentioned specifically. Fatty acids derived from soya oil are especially suitable.

(39) The unsaturated groups in the oxidatively drying polyunsaturated condensation product can be introduced by the fatty acids, but may, alternatively or additionally, be introduced by one or more of the polyols, carboxylic acids or anhydrides or other building blocks used, such as fatty mono-alcohols. The oxidatively drying polyunsaturated condensation product can for instance have pendant groups in an amount of more than 20%, e.g., more than 50%, or more than 65% by weight of the condensation product.

(40) A specific example of a suitable alkyd is the condensation product of soya oil, phthalic anhydride, and pentaerythritol.

(41) Optionally, the oxidatively drying polyunsaturated condensation product may comprise other building blocks, which can for example be derived from monocarboxylic acids such as pivalic acid, 2-ethylhexanoic acid, lauric acid, palmitic acid, stearic acid, 4-tert. butyl-benzoic acid, cyclopentane carboxylic acid, naphthenic acid, cyclohexane carboxylic acid, 2,4-dimethyl benzoic acid, 2-methyl benzoic acid, benzoic acid, 2,2-dimethylol propionic acid, tetrahydrobenzoic acid, and hydrogenated or non-hydrogenated abietic acid or its isomer. If so desired, the monocarboxylic acids in question may be used wholly or in part as triglyceride, e.g., as vegetable oil, in the preparation of the alkyd resin. If so desired, mixtures of two or more of such monocarboxylic acids or triglycerides may be employed.

(42) Optionally, isocyanates may also be used as building blocks for the oxidatively drying polyunsaturated condensation product. Suitable isocyanates include diisocyanates, such as 1,6-hexane diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl diisocyanate, and dicyclo-hexylmethane diisocyanate, and triisocyanates.

(43) The alkyd resins can be obtained by direct esterification of the constituent components, with the option of a portion of these components having been converted already into ester diols or polyester diols. Alternatively, the unsaturated fatty acids can be added in the form of a drying oil, such as sunflower oil, linseed oil, tuna fish oil, dehydrated castor oil, coconut oil, and dehydrated coconut oil. Transesterification with the polyols and, optionally, other building blocks will then give the final alkyd resin. This transesterification generally takes place at a temperature of from 115 to 250 C., optionally with solvents such as toluene and/or xylene also present. The reaction generally is carried out in the presence of a catalytic amount of a transesterification catalyst. Examples of suitable transesterification catalysts include acids, such as p-toluene sulphonic acid, a basic compound such as an amine, or compounds such as calcium oxide, zinc oxide, tetraisopropyl orthotitanate, dibutyl tin oxide, and triphenyl benzyl phosphonium chloride.

(44) General processes for the preparation of alkyd polyesters are described in Alkyd Resin Technology by T. C. Patton, Publisher John Wiley & Sons Inc. (1962), the disclosure of which is incorporated herein by reference.

(45) Alkyds are often characterized by their oil length. Oil length is defined as the weight percentage of fatty acid building blocks (calculated as their triglycerides) in the alkyd resin. Long oil lengths (55% or higher) result in improved oxidative drying, good substrate adhesion, excellent flow properties, good solubility in aliphatic solvents, and low viscosity, even with low solvent content. However, these alkyds show strong yellowing. Medium oil length alkyds (40-55%) also have good solubility but show a higher viscosity. Paint films made of medium oil length alkyds have better mechanical properties such as hardness and durability. Short oil length alkyds (less than 40%) require additional measures, such as the use of additional siccatives or amino resins, to obtain acceptable drying times. The catalyst according to the present invention can be used with alkyds of any oil length.

(46) Preferably the alkyds described herein have a final polymer acid value of from 1 to 20 mg KOH/g resin, thereby making them suitable for the preparation of the Mn complex drier in situ with the alkyd resin.

(47) Auto-Oxidizable Coating Composition

(48) The auto-oxidisable coating composition of the invention may comprise a liquid medium, that is a low viscosity solvent such as water, organic (co-)solvents and mixtures thereof.

(49) The composition of the present invention may be formulated as a solvent-borne coating composition. In this embodiment reactive diluents may be used to reduce the volatile organic content (VOC) below 300 g/l, a so-called high solids composition (solids content more than about 60%). However, it is also suitable for conventional coating compositions with a higher solvent content. In this context, VOC is determined in accordance with US standard ASTM D2369 (1 hr, 110 C.). Suitable solvents are, for instance, aromatic solvents such as toluene or xylene, as well as aliphatic solvents such as ethyl diglycol, ethyl glycol acetate, butyl glycol, butyl glycol acetate, butyl diglycol, butyl diglycol acetate, and methoxypropylene glycol acetate. Commercially available solvents are for instance Shellsol D40, an aliphatic hydrocarbon solvent available from Shell, Dowanol PMA from Dow, and Solvesso-150, available from ExxonMobil.

(50) Alternatively, the compositions according to the invention may be water-borne, can be used in an oxidatively drying water borne composition, optionally comprising co-solvents or humectants, such as glycols. Particularly useful for water borne compositions are reactive diluents with ionic or non-ionic stabilizing groups. These groups can, for example, be obtained by using diols or diesters containing carboxyl, sulfosuccinate or polyethylene glycol side groups.

(51) As is known in the art, surfactants may be utilized to assist in the dispersion of the auto-oxidizable (alkyd) resin in water. Suitable surfactants include, but are not limited to, conventional anionic, cationic and/or non-ionic surfactants.

(52) The liquid medium can also comprise reactive diluents, i.e. solvents which comprise functionalities which are able to react in the drying process with the unsaturated fatty acid residue comprising polymer. Thus, the reactive diluent is not co-reacted directly with the polymer, but participates to the drying process. Examples of such reactive diluents are the vinyl monomers described hereinabove.

(53) In a preferred embodiment of the invention, the composition of the present invention is used in solvent borne coating compositions, and in particular those which have dark colors, like Hammerite type of paints.

(54) The composition according to the invention can be used as a clear varnish or may contain pigments. Pigments can ordinarily include opacifying pigments, such as titanium dioxide, zinc oxide, leaded zinc oxide, or tinting pigments, such as carbon black, yellow oxides, brown oxides, tan oxides, raw and burnt sienna or umber, chromium oxide green, phthalocyanine green, phthalonitrile blue, ultramarine blue, cadmium pigments or chromium pigments. Fillers can also be added, such as clay, silica, talc, or mica.

(55) The coating composition can furthermore contain one or more additives such as secondary driers, UV stabilizers, co-solvents, dispersants, surfactants, inhibitors, fillers, anti-static agents, flame-retardant agents, lubricants, anti-foaming agents, extenders, plasticizers, anti-freezing agents, waxes, thickeners, or thixotropic agents.

(56) Furthermore, the coating composition according to the invention may optionally comprise various anti-oxidants and anti-skinning agents such as methylethylketoxime, acetonoxime, butyraldoxime, dialkylhydroxylamine, cyclohexanoneoxime or mixtures thereof. Where present, the concentration of antioxidant or anti-skinning compound applied is preferably in a range of from 0.001 to 2 wt. %, by weight of the composition.

(57) The total amount of primary manganese drier responsible for catalytic activity in the coating composition should not typically exceed 10 wt. %, based on the total resin weight, by weight of the composition, and preferably should be in the range from 0.01 to 3 wt. %, based on total resin weight. The amount of primary manganese drier is calculated on manganese plus multidentate ligand.

(58) The primary manganese drier may be used together with one or more auxiliary driers and/or coordination driers in order to enhance the activity of the primary drier and/or the final characteristics of the dried coating, such as hardness and glossiness. Auxiliary driers interact with the primary drier. Coordination driers form coordination complexes with hydroxyl groups within the alkyd composition and thus help to stabilize the polymer network of the alkyd composition. The total amount of the auxiliary and/or co-ordination driers in the coating composition should not typically exceed 10 wt. %, based on the total resin weight, by weight of the composition, and preferably should be in the range from 0.01 to 3 wt. %, based on total resin weight.

(59) Such auxiliary and/or coordination driers are typically polyvalent salts containing: barium, zirconium, calcium, bismuth, copper, zinc, iron, potassium, strontium, sodium, neodymium or lithium as the cation; and, halides, nitrates, sulphates, carboxylates like acetates, ethylhexanoates, octanoates and naphthenates or acetoacetonates as the anion. Metallic soaps, which are soluble in the binder of the coating composition, may in particular be mentioned in this regard; examples of such soaps, which may be used individually or in combination, include strontium octoate, copper octoate, zirconium octoate, zinc octoate and calcium octoate.

(60) Besides these driers, the coating composition may optionally comprise drying-accelerating complexing agents, for example, 2,2-bipyridyl and 1,10-phenantroline. The complexing agents can be added in an amount of from 0 to 3 wt. %, preferably from 0.1 to 1.5 wt. %, based on the weight of the total resin.

(61) Other ingredients that may be present in the coating composition depend on the envisaged application of the composition. Examples are antisettling agents, anti-sagging agents, de-airing agents, and the like. The sum of the amounts of the various additives will usually not exceed 5 wt. %, based on the total weight of the coating composition.

(62) The coating compositions of the present invention can be pigmented or un-pigmented and may find utility as an adhesive, as primer, as a topcoat, as a high-gloss or matt coating, as a stain-resistant coating, a wood oil, a wall paint or a flooring paint. The term paint is not intended to be limited in this context and incorporates varnishes, enamels and lacquers for architectural or industrial use, indoors or outdoors.

(63) Suitable substrates which may be coated with the auto-oxidisable coating composition of the invention include wood, wooden based substrates (e.g. MDF, chipboard), metal, stone, plastics and plastic films, natural and synthetic fibers, glass, ceramics, plaster, asphalt, concrete, leather, paper, foam, masonry and/or board. The application to such substrates may be effected by any conventional method, including brushing, dipping, flow coating, spraying, roller coating, pad coating, flexo printing, gravure printing, and ink-jet printing. For spraying, further dilution of the composition with a suitable solvent (for example acetone) may be required.

(64) The present invention will now be further illustratedbut in no way limitedby reference to the following examples.

EXPERIMENTAL

(65) Drying time were sssessed by one of two methods

(66) Dust-Free and Tack-Free Times

(67) To test the dust-free and tack-free drying stages of the coating compositions prepared in the Examples as described below, the composition was applied to a glass plate at a wet film thickness of 80 m. Drying time tests were performed at regular time intervals at relative humidity (RH) levels of 50 (5) %, temperatures of 23 (2) C. and an air flow 0.1 m/s. Dust-Free Time: the dust-free time was determined by dropping a piece of cotton wool (about 1 cm.sup.3 i.e. 0.1 g) onto the drying film from a distance of 25 cm. If the piece of cotton wool could be immediately blown from the substrate by a person without leaving any wool or marks in or on the film, the film was considered to be dust-free. Tack-Free Time: the tack-free time was determined by placing a piece of cotton wool (about 1 cm.sup.3, 0.1 g) on the drying film and placing a metal plate (with a diameter of 2 cm) and then a weight of 1 kg onto the piece of cotton wool (for 10 seconds). If the piece of cotton wool could be removed from the substrate by hand without leaving any wool or marks in or on the film, the film was considered to be tack-free.

(68) BK Drying Times

(69) Drying times were determined by BK drying on a BK or Braive recorder (wet film thickness, 90 m; ASTM D5895-96). After the application of the film on a glass strip (B. K. recorder: 692.5 cm; Braive recorder: 30.52.5 cm) a vertical blunt needle, pressed upon by a 5 g load, is placed into the freshly applied film and then dragged through the drying paint in a direction parallel to the edges of the strip.

(70) The three stages of BK drying in the experiment were as follows: a) the (wet) paint flows together (leveling); b) the paint has begun to polymerize but a line left by the needle is visible or traceable (basis trace); and, c) drying has proceeded sufficiently that the film of paint is not displaced by the needle (the so-called surface dry time). In Table 6 and onwards, the drying time of steps a, b and c is given, at either 10 or 23 C.

(71) The Knig hardness of the films was assessed using the pendulum damping test according to DIN53157. A glass panel was coated with a 60 m wet film, held at 23 C. and 50% RH and the hardness development in time was monitored with a Knig pendulum. The time (s) for the oscillation to reduce from an initial deflection 6 to a deflection of 3 was measured.

(72) A 60-degree (60) Novogloss gloss meter (available from Rhopoint Instrumentation) was used to measure the gloss of the coating formulation and of the coat formed in the Examples. With respect to measurement, an internal test method based on ASTM D2457 was used.

(73) As used herein: Mekoxime is methyl ethyl ketoxime (available from Rockwood); TMTACN is used as such, the liquid contains about 95% TMTACN; Sr-Drier is a strontium drier (18%, commercially available from Rockwood); and, Mn-Drier is a manganese octoate drier (10%, commercially available from Rockwood).

Example 1

(74) A first, base formulation was prepared in accordance with the ingredients and proportions (parts by weight) shown in Table 1 below.

(75) TABLE-US-00001 TABLE 1 Formulation A Parts By Weight Ingredient 630.0 Long oil alkyd (65% oil length) 542.9 Phenolic resin (Setal 538) 13.0 Bentonite 30.0 Castor oil 192.0 Talcum 1074.8 Micaceous iron oxide (Portafer AP 75) 13.5 Aluminium paste (Stapa 88) 391.3 Aliphatic solvent (Shellsol D40) 37.8 Aromatic solvent (Shellsol A100)

(76) Into this base formulation was mixed Mekoxime and the Mn and Sr commercial driers. The TMTACN liquid was then added thereto, under stirring, to form the coating compositions as defined in Table 2 below.

(77) TABLE-US-00002 TABLE 2 Mn- Sr-Drier Drier TMTACN Formulation A Mekoxime (Parts (Parts (Parts Mn:TMTACN Coating (Parts by (Parts by by by by (Molar Formulation weight) weight) weight) weight) weight) Ratio) *1 97.72 0.4 1 0.66 0.22 1:1 2 97.56 0.4 1 0.825 0.22 1.25:1 3 97.39 0.4 1 0.99 0.22 1.5:1 4 97.06 0.4 1 1.32 0.22 2:1 *Comparative example

(78) The hardness and drying performance of these coatings is shown in Table 3.

(79) TABLE-US-00003 TABLE 3 Knig Hardness (s) Coating Dust-free Drying Tack-free Drying 1 7 28 Formulation time (minutes) time (minutes) Day Days Days 1 130 315 11 26 37 2 110 290 11 28 40 3 110 165 13 30 44 4 150 340 13 33 50

Example 2

(80) A further base Formulation B was prepared in accordance with the ingredients and proportions shown in Table 4.

(81) TABLE-US-00004 TABLE 4 Formulation B Parts By Weight Ingredient 624.0 Long oil alkyd (67% oil length) 60.0 Dispersing Agent 243.0 Sodium Potassium Alumina Silicate 297.0 Aliphatic solvent (Shellsol D40) 990.0 TiO.sub.2 205.5 Urethane alkyd

(82) Into this base formulation was mixed Mekoxime and the Mn and Sr commercial driers. The TMTACN liquid was then added thereto, under stirring, to form the coating compositions as defined in Table 5 below (amounts in parts by weight; Mn:TMTACN ratio as molar ratio).

(83) TABLE-US-00005 TABLE 5 Coating Mn- Formulation Formulation B Mekoxime Sr-Drier Drier TMTACN Mn:TMTACN *5 96.72 0.4 2 0.66 0.22 1:1 6 96.39 0.4 2 0.99 0.22 1.5:1 7 96.06 0.4 2 1.32 0.22 2:1 *Comparative example

(84) The hardness and drying performance of these coatings is shown in Table 6.

(85) TABLE-US-00006 TABLE 6 Dust-free Tack-free Knig Hardness Drying Drying (s) Coating Gloss >60 time time 1 7 28 Formulation (1 day) (minutes) (minutes) Day Days Days 5 41.9 50 230 16 31 48 6 78.9 90 400 15 32 49 7 80.8 130 795 15 32 51

Example 3

(86) A further base Formulation C was prepared in accordance with the ingredients and proportions shown in Table 7.

(87) TABLE-US-00007 TABLE 7 Formulation C Ingredient Parts By Weight Name Description 57.3 Setal 270 SM-70 long oil alkyd resin soyabean oil based 2 Nuodex Ca 5 Ca carboxylate in organic solvent (5 wt % Ca) 2 Nuodex Zr 18 Zr carboxylate in organic solvent (18 wt % Zr) 0.5 Exkin 2 methyl ethyl ketoximine 3.8 Shellsol D40 hydrotreated heavy naphtha petroleum 0.09 Borchigen 911 Amphoteric surfactants blend 0.2 Bentone SD-1 organic derivative of a bentonite clay 23.7 Tioxide tr 92 titanium dioxide, rutile

(88) Into this base formulation was mixed solvent (hydrotreated heavy naphtha petroleum), stock solution of the Mn commercial drier in the same solvent and stock solution of the TMTACN liquid in the same solvent, to form the coating compositions as defined in Table 8 below (amounts in parts by weight; Mn:TMTACN ratio as molar ratio).

(89) TABLE-US-00008 TABLE 8 Coating Formulation Mn: Formulation C Solvent Mn-Drier TMTACN TMTACN 8 89.5 10.4 0.05 0.0078 2:1 *9 89.5 10.4 0.05 0.016 1:1 10 89.5 10.5 0.025 0.004 2:1 *11 89.5 10.5 0.015 0.005 1:1 *Comparative example

(90) The hardness and drying performance of these coatings is shown in Table 9.

(91) TABLE-US-00009 TABLE 9 Knig Hardness (s) Coating BK drying 10 C. BK drying 23 C. 1 7 14 Formulation (hours) (hours) Day Days Days 8 8.5 5.5 12 17 15 9 8.5 5 9 12 13 10 14.5 9.75 12 18 17 11 12.5 8.25 10 15 16

(92) Various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications are covered by the appended claims.