GB1583316A

GB1583316A - Coating compositions

Info

Publication number: GB1583316A
Application number: GB21979/78A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1977-05-25
Filing date: 1978-05-24
Publication date: 1981-01-21
Also published as: IT1096318B; FR2392092A1; IT7823744A0; FR2392092B3; DE2723492A1; DE2723492C2

Description

(54) IMPROVEMENTS IN OR RELATING TO COATING COMPOSITIONS (71) We, HOECHST AKTIENGESELLSCHAFT, a body corporate organised under the laws of the Federal Republic of Germany of 6230 Frankfurt Main 80, Germany do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to hardenable coating compositions based on hydroxyl group containing oligomers or polymers.

It is known that oligomers or polymers containing oxirane rings may be hardened in solution or in solvent-free systems using acid anhydrides such as, for example, phthalic acid anhydride, hexahydrophthalic acid anhydride, trimellitic acid anhydride and pyromellitic acid anhydride, at elevated temperatures, e.g.

above 140"C. In practice, similar systems for hardening oligomers or polymers containing hydroxyl groups using anhydrides of the above type in liquid form and especially in solution are not acceptable. Although bisanhydrides of trimellitic acid esters have been described as hardeners for hydroxyl group containing polymers, no technically useful systems of this type have been published. This arises from the fact that these systems are not suitable for cold hardening or for heat drying, as at temperatures below 1400C the bisanhydride esters show insufficient reactivity. In addition, the surface coatings obtained are not sufficiently resistant to water, alkalis and acids, and also show poor weathering properties.A further serious disadvantage of the use of bisanhydride esters in coating compositions is their low solubility in solvents used therefor and their high tendency towards crystallisation from these solvents. In other technically available bisanhydrides such as for example pyromellitic acid anhydride, diphenyltetracarboxylic acid bisanhydride and benzophenonetetracarboxylic acid anhydride, this disadyantage is even more pronounced, that is, they are virtually insoluble in the solvents conventionally used for coating compositions.

We have now found, that these disadvantages may be overcome if a hardenable multi-component system is used as a binding agent, especially for coating compositions, which comprises a mixture of an ester anhydride and a hydroxyl group containing oligomer or polymer, together with at least one chelated aluminium and/or titanium compound.

Thus, according to one aspect of the present invention there is provided a hardenable coating composition which contains A) at least one hydroxyl group containing oligomer or polymer having a hydroxy number of from 25 to 300, B) at least one ester anhydride containing at least two anhydride groups, and C) at least one chelated aluminium or titanium compound, wherein at least one of the components A), B) or C) is in the form of a paste and/or the composition additionally comprises a solvent to form a flowable coating composition.

The coating composition according to the invention is preferably in the form of a solution.

The ester anhydrides for use as component B) in the compositions of the present invention are preferably those of formula

or corresponding oligomers of formula

in the above formulae R represents a di- or trivalent straight-chained or branched aliphatic hydrocarbon group having from I to 28, preferably 1 to 15 carbon atoms, which may be optionally interrupted by at least one ether bridge or by from one to three -HC = CM- groups and/or substituted by an ester group having 1 to 6, preferably I to 3 carbon atoms, or by a COOH group; Z represents the integer 2 or 3; and U represents an integer from 1 to 5.

In compounds of formulae I and Ia, R preferably represents a straight-chained or branched alkylene group having from 2 to 8, preferably 2 to 4 carbon atoms, or a straight-chained or branched alkylene group interrupted by one or two ether bridges, which preferably has 2 to 6 carbon atoms. In general, the ester anhydride component B) is used in the form of a mixture of monomers of formula I with oligomers of formula Ia. It is, however, also possible to use an oligomeric substance which has, for example, anhydride groups and optionally additional free COOH and/or ester groups. When using mixtures of compounds of formula I and Ia, the percentage weight ratio of the compounds of formula I to oligomers of formula Ia is advantageously from (10:90) to (90:10) and preferably from (20:80) to (80:20).

Furthermore, a mixture of the ester anhydride component B) with trimellitic acid anhydride may also be used. In this case, the proportion of trimellitic acid anhydride is preferably at most 25% by weight, e.g. 0.5 to 20, preferably 3 to 15% by weight, referred to the sum of the compounds of formula I and Ia.

If the ester anhydrides of component B) are used in the form of mixtures, their constitution may advantageously be determined by gel permeation chromatography using polystyrene gel cross-linked with divinylbenzene as the stationary phase and tetrahydrofuran as the eluent. Using this method it is possible to determined exactly the individual components of the ester anhydride mixtures, so that the proportion of individual components may be adjusted easily and exactly.

In addition, compounds of formula I and trimellitic acid anhydride, as well as the oligomeric bisanhydrides of formula Ia may be separated according to the number of aromatic nuclei and exactly determined quantitatively.

Oligomers or polymers containing hydroxyl groups which may be used as component A) are, for example, a) saturated and/or olefinically unsaturated polycondensation products, b) addition polymerisation products and c) mixtures thereof, preferably with an OH number of from 40 to 200.

Examples of such hydroxyl group containing polymers or oligomers are saturated or unsaturated polyesters having free OH groups; homopolymers or copolymers having OH groups, e.g. those based on hydroxyalkyl esters of acrylic and/or methacrylic acid, with optionally olefinically unsaturated monomers; polyvinylalcohol; phenolic resins having free hydroxymethyl and/or hydroxyethyl groups; amine resins, such as melamine resins, especially, however, urea resins with N-alkylol groups.

The polyesters may be prepared from known polycarboxylic acids such as, for example, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, adipic acid, fumaric acid, maleic acid and endomethylenetetrahydrophthalic acid, optionally together with monocarboxylic acids such as benzoic acid, butylbenzoic acid, lauric acid, isononanic acid, fatty acids of naturally occurring oils, or from mixtures of the said acids.Alcohol components of these polyesters are, for example, known polyhydric alcohols such as ethyleneglycol, propandiols, butandiols, pentandiols, hexandiols, diethyleneglycol, trimethylolethane or propane, pentaerythritol, dipentaerythritol, bis-hydroxyethyl-iso- or -terephthalic acid ester, and tris-hydroxyethyl isocyanurate, optionally together with monohydric alcohols such as, for example, lauryl alcohol, octyl alcohol and linoleyl alcohol, either individually or in admixture.

In addition, it is possible to prepare the polyesters of component A) by at least partial chemical decomposition of high-molecular polyesters of aromatic nature, such as, for example, terephthalic acid ethyleneglycol or butandiol polyesters, isophthalic acid ethyleneglycol or hexandiol polyesters, by reaction with monoand/or polyfunctional alcohols, esters or dicarboxylic acids. When using monohydric alcohols these may be reacted in less than equivalent amounts.

The oligomers or polymers of component A) may also contain as reactive groups in addition to hydroxyl groups, oxirane rings in amounts of from 0.05 to I ring per OH group. For such modifications, epoxide resins may be used which are prepared in a way known per se from phenols, epichlorohydrin and optionally alcohols and which are themselves optionally modified with acids to form esters or with diketenes to form acetic acid ester groups. Furthermore, epoxide resins in the form of glycidyl esters may be used which have been obtained e.g. by esterification of epoxide compounds such as epichlorohydrin or oligomeric alkylene oxides with saturated or unsaturated carboxylic acids, e.g. phthalic acid, isophthalic acid, hexahydrophthalic acid, adipic acid, acrylic acid, methacrylic acid, maleic acid and fumaric acid or oligomeric carboxyl compounds such as oligomeric carboxylic acid esters.

Other epoxy compounds which may be used for modifying component A) are, for example polyepoxide alkanes containing from 4 to 20, preferably 4 to 12, carbon atoms and having from 2 to 6, preferably 2 to 4 oxirane rings.

In addition, it is possible to use epoxidised butadiene oils and their alkylation products, e.g. isoprene oils; aliphatic glycidyl ethers, e.g. glycidyl ethers of polyols such as ethyleneglycol, diethylene- and/or triethyleneglycol, 2,2-dimethylpropandiol, 1,2- or 1,3-propandiol, 1,4- or 1,3-butandiol, 1,5-pentandiol, 1,6hexandiol, glycerol, trimethylolpropane, cyclohexyldimethanol, glycidyl ethers containing siloxane groups; epoxidised fatty acid esters, e.g. epoxidised soya-bean oil, epoxidised linseed oil, or dimeric and/or trimeric compounds of this type; alicycle bis-epoxides, e.g. vinylcyclohexenedioxide, limonene dioxide, bis(epoxycyclohexyl)-methane or -propane, dicyclopentadiene dioxide, bis (epoxycyclopentyl)-ether; epoxidised aliphatic and/or cycloaliphatic allyl ethers and/or allyl esters e.g. bis-(epoxypropyl)-hexahydrophthalate, bis-(epoxypropyl)adipate; epoxidised polyesters and/or oligomeric or polymeric glycidyl acrylic or methacrylic acid esters and/or their copolymers, e.g. with acrylic or methacrylic acid esters, maleic acid esters, ethylene, propylene, butylene, styrene, vinyltoluene, a-methyl-styrene, vinylcyclohexane; or trimerised epoxide compounds, e.g.

triglycidyl isocyanurate; either alone or in admixture. It is also possible to use as component A), epoxides which have been obtained by reacting the polycarboxylic acid groups of compounds of formula I with OH or epoxide groups of epoxides to form esters which still contain epoxide groups.

Additionally, mixtures of the above compounds with monoepoxides may be used. Example of monoepoxides which may be used being olefin oxides, such as octylene oxide, butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, pbutyl-phenyl glycidyl ether, cresyl glycidyl ether, 3-(pentadecyl)-phenyl glycidyl ether, styryl oxide, glycidyl methacrylate, cyclohexene vinyl monooxide, dipentene monooxide, a-pinene oxide, and glycidyl esters of tert.-carboxylic acids.

Aluminium compounds which may be used as component C) include, for example, compounds of general formula

in which R3, R4 and R6, which may be the same or different, each represents, a chelating group, e.g. a group of formula

in which R' represents an alkyl group having from 1 to 4 carbon atoms, e.g. a methyl, ethyl, propyl, isopropyl, butyl or isobutyl group; and R2 represents an alkyl group having up to 7 carbon atoms, e.g. the aforesaid groups for Rs or a pentyl, hexyl, heptyl, or cyclohexylmethyl group, or a benzyl or methylbenzyl group. It will be appreciated that very different groups for R3 to R3 are possible.

Further aluminium compounds which may be used for component C) are, for example, those of general formula

wherein the groups R3, which may be the same or different, are as hereinbefore defined and R6 represents a divalent transition metal or a divalent aliphatic, cycloaliphatic or araliphatic hydrocarbon group having from 2 to 21 carbon atoms and optionally interrupted by at most two ether bridges. R6 preferably represents a group of the formula HCH2)n (Va) (n = 2-8)

and in the group of formula Va the alkylene group may be interrupted by at most two ether bridges.

When RB represents a diyalent transition metal this is preferably selected from Fe", Co", Mn", Zn" and Mo".

In compounds of formulae II and IV up to two of the chelating groups R3 to R5 may be of the formula

(in which the groups R7, which may be the same or different, each represents a -CH3 or -C2H5 group).

Titanium compounds with tetravalant titanium which may be used as component C) in the compositions of the invention are, for example, those in which aluminium is replaced by titanium in the above-mentioned aluminium containing compounds, subject of course to the tetravalence of the Ti atom, as well as compounds of formula

(in which each of the groups R8 which may be the same or different, represents a -C2H5, -C3H7 a nd/or -C4H9 group and each of the groups R9, which may be the same or different represents a chelating group, preferably at least one chelating group of formulae VIa to VIc as defined above).

It is also possible to use mixtures of these metal compounds as component C).

Preferred compounds for incorporation into component C) of the composition according to the invention are

The relative amounts of ester anhydrides, hydroxyl group containing oligomers or polymers and metal compounds in the compositions according to the invention are generally 10 to 50, preferably 15 to 40% by weight of ester anhydride, 15 to 90, preferably 30 to 82% by weight of hydroxyl group containing oligomers or polymers and 0.1 to 35, preferably 3 to 30% by weight of metal compounds.

The three components of the compositions according to the invention may be mixed in any sequence desired, but preferably in the presence of one or more solvents such as, for example, aromatic or aliphatic hydrocarbons, esters, ketones, chlorinated hydrocarbons and nitrated hydrocarbons. The particular constitution of the compositions enables pot times at room temperature to be adjusted from, for example, less than one minute up to several weeks. The systems with extremely short pot times are especially suitable for two-component injection by means of a device similar to a Daniell cock.

Since the metal compounds may be in the form of pastes they are especially suitable for the preparation of flowable multi-component systems according to the invention by virtue of the fact that they enable such systems to be produced in the absence of solvents if desired or in the presence of quantities of solvents which are insufficient to dissolve the entire solid components.

In the preparation of the compositions of the invention it is preferred to mix a solution of the metal compound(s), component C), with a solution of the ester anhydride(s), component B). It is also possible to add any solid component(s) to a solution of just one component. If atmospheric moisture is excluded, these mixtures can be stored for almost unlimited periods. Before processing a solution of the hydroxyl group containing oligomers or polymers, component A), is added to the mixtures prepared above.

Hardening of the multi-component compositions according to the invention generally takes place at temperatures of approximately OOC to 3200 C, and preferably at 200C to 1600C. The high reactivity of these compositions is shown, however, in particular if they are stoved at relatively high temperatures, e.g. at 200 to 2500C (substrate temperature) and over very short times, e.g. I to 3 minutes (socalled shock drying). If solvents are used in the preparation of the compositions it is necessary to ensure that solvent vapours given off are evacuated off in order to obtain good surface properties.

The coating compositions according to the invention may be formulated in a manner conventional for coating composition production. Thus, the total mixture of the individual components thereof may have added thereto one or more pigments, dyestuffs, fillers, softeners, stabilisers, wetting agents, dispersing agents, lubricants, flow agents, UV-absorbing agents, catalysts and other additives as desired.

Dyestuffs and/or pigments will generally be incorporated into the compositions according to the invention when they are used as paints, e.g. as corrosion-resistant primers, undercoats or finish coatings. The weight ratio of the solids content of the binding agent to the total quantity of pigment advantageously is in the range from 1:0.1 to 1:10, preferably 1:0.5 to 1:5.

Dyestuffs or pigments which may be used in the compositions are for example, titanium dioxide, graphite, soot, zinc chromate, strontium chromate, barium chromate, lead chromate, lead cyanamide, lead silicochromate, calcium molybdate, manganese phosphate, zinc oxide, cadmium sulphide, chromium oxide, zinc sulphide, nickel titanium yellow, chromium titanium yellow, red iron oxide, black iron oxide, ultramarine blue, phthalocyanine complexes and naphthol red.

Surprisingly, we have found that it is of no importance whether the colouring pigment or dyes are of an inorganic and organic nature.

Fillers which may be used are, for example, talc, mica, kaolin, chalk, quartz power, asbestos dust, ground shale, barium sulphate, silicates, glass fibres and organic fibres.

Flow agents which may be used include, for example, ketone resins; telomerisates containing anhydride groups, such as styrene-maleic acid anhydride telomerisates; oligomeric acrylic or methacrylic acid esters; silicon oils; lowmolecular melamine resins and fluoroalcohols.

Catalysts which may be used in the compositions to accelerate the hardening process include, for example, inorganic or organic basis, such as, for example, lithium, sodium or potassium salts of organic and/or inorganic acids, such as acetic, benzoic, salicyclic, stearic or carbonic acid; or organic bases such as diazabicyclooctane, N,N'-tetraalkyl-ethylenediamine or -hexylenediamine, imidazole, imidazoline, morpholine and their aryl and alkyl substitution products; also N,N'bis-(dialkylaminoalkyl)-oxamides such as N,N'-bis-(diethylaminomethyl)-oxamide.

To increase solubility, the lithium, sodium or potassium salts can also be used in the form of complex compounds thereof, e.g. with crown ethers. Other catalysts which may be used are organic tin compounds such as dibutyl-oxotin, dioctyl-tin dilaurate as well as salts of zinc, calcium and magnesium such as zinc acetate, calcium adipate and magnesium palmitate. Mixtures of several catalysts may also be employed. The catalysts are generally used in a proportion of 0.01 to 5, preferably 0.05 to 1.5% by weight, referred to the total solids content of the compositions.

The coating compositions according to the invention may be applied to diverse substrates, provided that these are able to withstand the hardening temperatures of the coating.

Substrates to which the coatings according to the invention adhere well are for example, wood, ceramics, glass, brickwork, concrete, gypsum, plastics, and preferably metals such as, for example, iron, zinc, copper, aluminium, steel, brass, bronze and magnesium. If desired, the substrates can be made more susceptible to adhesion of the coating or more resistant to corrosion by suitable mechanical and/or chemical pretreatment. However, we have found that the coating compositions according to the invention adhere excellently to the most diverse metal substrates in the absence of an adhesion-assisting primer or undercoat. We have found that the adhesion of coatings according to the invention corresponds to the values GT 0A to GT 1A according to the test regulations of DIN 53151.

Thus, from another aspect, the invention also provides a method of adhering two substrate surfaces together which comprises applying a composition according to the invention to at least one of said surfaces and bringing the surfaces together.

As indicated above coating compositions according to the present invention may be suitable for the preparation of corrosion-protective coatings and/or undercoats for various applications, especially as resistant paints. Furthermore, they may be used for the coating and lining of objects which come into contact with propellants and/or solvents and also for coatings for protection against atmospheric influences, such as road markings, coatings for household appliances, machines, vehicle parts, structural parts for electrotechnical purposes or elements thereof, especially for electrical conductors, as well as coatings for objects subject to thermal stresses.

Due to their favourable properties, the coating compositions according to the present invention may be used for single-layer enamelling. Depending on the choice of oligomers or polymers, sheets coated with the coating compositions according to the invention may subsequently be deformed, for example, by deepdrawing, folding, profiling, stamping or the like without significant impairment of the favourable properties of the coatings. The coating applied may remain unchanged, but it may also serve as an undercoat, that is, as a substrate for further coatings which may, consist of the same coating or alternatively another conventional coating composition.

The coating compositions of the present invention produce glossy films with good mechanical and chemical resistance and with good stability towards weathering. We have also found it possible, on the other hand, to produce, as desired, especially by a mixture of polyesters and additional epoxy resins in combination with the ester anhydrides according to the invention; matt lacquers having good mechanical and chemical properties. Surprisingly, large quantities of pigments and fillers are not required for this purpose.

The coating compositions according to the present invention may be employed wherever other multi-component coating systems such as epoxide resin, melamine resin or isocyanate systems are applied. In cold hardening especially, the compositions according to the invention are distinguished by rapid drying times.

The compositions according to the invention may also be suitable in solid form for the preparation of two-component adhesives, e.g. for the preparation of highly reactive mclt adhesives and for liquid and/or solvent-containing, thermosetting adhesives. They may also be used as binding agents for textile, organic and/or inorganic materials. The compositions according to the invention are likewise suitable for use in the preparation of hardenable moulding materials, coating resins, cements, cellular or porous substances, such as, for example, foam bodies, and as insulating enamels.

As a result of the numerous possibilities for varying the compositions according to the invention it is possible to achieve optimum adaption to the intended use at any given time. This applies especially to pot times, film hardness and film elasticity which may be varied within wide limits. A further important advantage of the present compositions is that they are not toxicologically objectionable, and in this respect, they are superior especially to hardenable compositions based on isocyanate compounds and to epoxide resins based on amines. The coatings obtained from the compositions according to the invention are highly resistant to water, alkalis, acids and organic solvents, and, in addition are UV-absorbing and have weather-protecting properties.

The following Examples serve to illustrate the preparation of the compositions according to the invention.

Table 2 below sets out details of the components A), B) and C) used in each Example, subject to the Notes following the Table.

The ratios given are volume ratios and the percentages given are percentages by weight, unless specified otherwise. The properties of the coatings obtained according to Examples 1 to 7 are set out in Table 3.

Table 1 gives a list of the abbreviations used hereinafter.

Unless specified otherwise, the ester anhydride component B) in the Examples was prepared from 1,2-propandiol and trimellitic acid anhydride. The composition of components A) and B) was determined by gel chromatography.

TABLE I T - parts by weight MMA - methyl methacrylate MA - methacrylate Bu - butyl TMP - trimethylolpropane NPG - neopentyl glycol PE - pentaerythritol IPDM - dimethylisophthalate TMSTM - trimethyl trimellitate PSA - phthalic acid anhydride TMSA - trimellitic acid anhydride TCLPSA - tetrachlorophthalic acid anhydride EGA - ethyleneglycol-monoethylether acetate MIK - methylisobutyl ketone MEK - methylethyl ketone DMF - dimethylformamide E-acetate - ethyl acetate TABLE 2 Example 1 2 3 4 5 6 7 8 COMPONENT A Styrene, MMA Styrene, Bu-MA, MMA, TMP PE, NPG IPDM, NPG, TMP Propandiol, OH-ethyl-MA Bu-MA, OH- OH-propyl-+ hexandiol pentandiol, TMSTM, hexandiol, hexandiol, bu-acrylate propyl- OH-butyl NPG, PSA PSA-bis-OH- NPG, pro- PSA, TMSA, PE, TCLPSA acrylate acrylate adipic acid ethyl tere- pandiol, epichloro PSA phthalate glycerol hydrin T/Solution 650/50% 660/40% 840/60% 600/50% 620/50% 775/55% 759/60% 500/45% OH number 150 80 40 130 100 40 110 170 Mn 3100 5000 1200 2500 9000 3000 950 1100 Viscosity - - - 1700 10500 2600 800 Epoxide number - - - - - - 15 Solvent EGA-xylene EGA Bu-acetate- EGA-xylene Bu-acetate Bu-acetate Bu-acetate Bu-acetate 1:1 toluene 1:3 MIK MEK MIK MEK 9:1 1:1 1:1 6:4 2:1 COMPONENT B TMSA % 2 6 17 6 11 Bis-anhydride % 68 48 74 as Example 1 36 48 as Example 1 as Example 15 Oligomeric bis- 30 46 9 58 41 anhydride % T/Solution 300/50% 217/40/% 140/60% 290/50% 245/50% 155/55% 216/60% 300/50% Solvent EGA-Bu- EGA-E- EGA-MEK as Example 1 EGA-MEK EGA-DMF as Example 1 EGA acetate acetate 55:45 8:2 93:7 9:1 7::3 COMPONENT C Formula VIII IX X XI XII XIII XIV XV T/Solution 140/50% 123/40% 20/60% 100/50% 135/50% 70/55% 35/60% 200/50% Solvent Xylene Xylene Xylene- toluene Xylene- Xylene- toluene toluene ligroin heptane EGA 9:1 1:1 1:1 Notes on the Examples Example I.

I) The solution of the component A) described in Table 2 is mixed with a pigment of titanium dioxide in a bead mill in a weight ratio of 1:1. 5 T of N,N'tetramethylethylenediamine are then admixed with the mixture as hardening accelerator.

Component C) is prepared from aluminium ethylate, ethyl acetate and acetyl acetone in xylene.

Example 2.

Component C) is prepared from aluminium isopropylate, ethyl acetate and acetyl acetone in xylene.

Example 3.

Component C) is prepared from aluminium isopropylate and 1,3-propanediol followed by re-esterification with an ethyl acetate/acetyl acetone mixture (1 mol: 1 mol).

Example 5.

Component B) is obtained from trimellitic acid anhydride, diethyleneglycol and trimethylolpropane.

Component C) is prepared by the method of Ph. Teyssié et al, J. Polymer Science 15, 856 to 873 (1977).

Example 6.

Component B) is prepared from ethyleneglycol and trimellitic acid anhydride.

Component C) is prepared from tetraisopropyl-O-titanate and N,N-methylaminoethanol in known manner.

Example 7.

Component A) is a polyester glycidyl ester resin and is prepared by reesterification of the polyester with epichlorohydrin in the presence of an HCI acceptor.

Component C) is prepared from tetrabutyl-O-titanate, methyl acetate and acetyl acetone in toluene.

Enamelling Test In Examples 1, 2 and 4 to 6 solutions of components B) and C) are mixed together and the mixture can be stored indefinitely in this form if atmospheric moisture is excluded. The mixture is then mixed with the pigmented resin solution of component A) (which in Examples 2 and 4 to 6 is pigmented in the same way as that of Example 1), the viscosity of the solution is adjusted to be suitable for spraying with the desired solvent, e.g. butyl acetate.

The solution is then sprayed onto degreased phosphated steel sheets, in an amount sufficient to give a dry film thickness of 35 ,um (Examples 1 and 2), 30 ssm (Example 4), 40 ssm (Example 5) and 25 pm (Example 6).

In Example 3, the solutions of components A), B) and C) are mixed simultaneously until homogeneous and 100% by weight of a pigment of titanium dioxide relative to the proportion of solids, are admixed.

While diluting with xylene/methyl acetate (50:50) to give a suitable viscosity for spraying, 3 g of 2-phenylimidazoline are stirred in as hardening accelerator.

In . Example 7, the solutions of components A) and C) are mixed homogeneously together in a bead mill and simultaneously pigmented with titanium dioxide (weight ratio 1:1.3 relative to the solids content).

Before coating is carried out, the solution of component B) is admixed and degreased steel sheets are painted with a roller to give a film thickness of 35 pm.

In Example 8, the solutions of components B) and C) are homogenised in a ball mill with the addition of 6 g of lithium benzoate and 1.5 g of N,N'-bis-(dibutylaminoethyl)-oxamide. The light, cloudy mixture obtained is stable for at least four months.

Solution A is homogenised likewise in a ball mill with the addition of 0.5 g of N-methylmorpholine, 1.5 g of 2-phenyl-imidazoline and 2 g of lithium benzoate. A storable, opalescent solution is obtained.

The catalysed mixture of components B) and C) is applied to a degreased copper sheet with a doctor of 10 ssm and the catalysed solution of component A) is applied to a degreased copper sheet in like manner with a doctor of 15 ssm. After an air exposure time of 20 minutes, the coated sides of the sheets are brought into contact and subjected to a brief pressure of 30 bars. The tensile shearing strength of the adhesion is 32 N.mm-2 after storage for 8 days at room temperature.

The properties of the coatings obtained according to Examples 1 to 7 are given in the following Table 3.

TABLE 3 Konig pendulum hardness+) in S; after storage Erichsen Water- Xylene Pot time at Hardening time of depression proofness resistance room temperature Example at C 1 day 14 day mm h min h 1 R.T.+/7 days 157 202 9 100 120 12 1 100/30 min 207 227 5 120 120 1 160/30 min 235 235 4 200 120 2 R.T.+/7 days 126 169 9 > 100 3 24 2 100/30 min 186 189 6 > 100 5 2 160/30 min 193 192 4 > 100 7 3 R.T.+/7 days 105 125 7 2 < 1 48 3 100/30 min 135 142 5 20 < 1 3 160/30 min 140 145 3.5 > 100 < 1 4 R.T.+/7 days 105 195 9 > 200 > 100 4 4 100/30 min 197 206 9.5 > 200 > 100 4 160/30 min 212 210 9.3 > 200 > 100 5 R.T.+/7 days 95 180 9.5 > 80 60 14 5 100/30 min 185 192 8.2 > 100 > 100 5 160/30 min 197 195 7.5 > 100 > 100 6 R.T.+/7 days 85 140 9.5 > 100 3 73 6 100/30 min 135 168 8.4 > 100 7 6 160/30 min 170 173 6.3 > 100 7 7 R.T.+/7 days 120 165 7.5 30 35 18 7 100/30 min 180 195 8.2 100 60 7 160/30 min 230 232 9.8 > 200 > 120 +) R.T. = room temperature = ca. 20 C; +) Pendulum hardness according to Konig = DIN 53 157

Claims

WHAT WE CLAIM IS:

1. A hardenable coating composition which contains A) at least one hydroxyl group containing oligomer or polymer having a hydroxy number of from 25 to 300, B) at least one ester anhydride containing at least two anhydride groups, and C) at least one chelated aluminium or titanium compound, wherein at least one of the components A), B) or C) is in the form of a paste and/or the composition additionally comprises a solvent to form a flowable coating composition.

2. A composition as claimed in claim 1 wherein component B) comprises at least one compound of formula

or a corresponding oligomer of formula

in which R represents a di- or trivalent straight chained or branched aliphatic hydrocarbon group having from 1 to 28 carbon atoms optionally interrupted by at least one ether bridge or by from one to three -HC = CH-- groups and/or substituted by an ester group having 1 to 6 carbon atoms or by a -COOH group; Z represents the integer 2 or 3; and U represents an integer from 1 to 5.

3. A composition as claimed in claim 2 wherein component B) comprises a compound of formula I or an oligomer of formula Ia in which K represents an aliphatic hydrocarbon group having from I to 15 carbon atoms.

4. A composition as claimed in either of claims 2 and 3 wherein the group R in the compound of formula I or oligomer of formula Ia is substituted by an ester group having from 1 to 3 carbon atoms.

5. A composition as claimed in any of claims 2 to 4 wherein R in the compound of formula I or oligomer of formula Ia represents a straight-chained or branched alkylene group having from 2 to 8 carbon atoms or a straight-chained or branched alkylene ether group having from 2 to 6 carbon atoms.

6. A composition as claimed in claim 5 wherein R in the compound of formula I or oligomer of formula Ia represents a straight-chained or branched alkylene group having from 2 to 4 carbon atoms.

7. A composition as claimed in any of claims 2 to 6 wherein component B) comprises a mixture of compounds of formula I with oligomers of formula Ia.

8. A composition as claimed in claim 7 wherein the percentage weight ratio of compounds of formula I to oligomers of formula Ia is from (10:90) to (90:10).

9. A composition as claimed in claim 8 wherein the percentage weight ratio is from (20:80) to (80:20).

10. A composition as claimed in any of the preceding claims wherein component B) additionally comprises trimellitic acid anhydride.

Il. A composition as claimed in claim 10 wherein the proportion of trimellitic acid anhydride is at most 25% by weight referred to the sum of the compounds of formula I and Ia.

12. A composition as claimed in claim 11 wherein the proportion of trimellitic acid anhydride is from 0.5 to 20% by weight.

13. A composition as claimed in claim 12 wherein the proportion of trimellitic acid anhydride is from 3 to 15% by weight.

14 A composition as claimed in any of the preceding claims wherein component A) has a hydroxy number of from 40 to 200.

15. A composition as claimed in any of the preceding claims wherein component A) comprises a) a saturated or olefinically unsaturated polycondensation product, b) an addition polymerisation product, or c) a mixture thereof.

16. A composition as claimed in any of the preceding claims wherein component A) comprises a polyester.

17. A composition as claimed in any of the preceding claims wherein the oligomers or polymers of component A) additionally contain from 0.05 to 1 oxirane ring per hydroxyl group.

18. A composition as claimed in any of the preceding claims wherein component C) comprises a compound of formula

(in which R3, R4 and R5, which may be the same or different, each represents a chelating group).

19. A composition as claimed in any of claims I to 17 wherein component C) comprises a compound of formula

(wherein the groups R3, which may be the same or different, are as defined in claim 18, and R6 represents a divalent transition metal or a divalent aliphatic, cycloaliphatic or araliphatic group having from 2 to 21 carbon atoms and optionally interrupted by at most two ether bridges).

20. A composition as claimed in claim 18 or 19 wherein R3, R4 and R5 in the compound of formula II or IV each represents a group of formula

(in which R' represents an alkyl group having from 1 to 4 carbon atoms; and R2 represents an alkyl group having from I to 7 carbon atoms, or a cyclohexylmethyl, benzyl or methylbenzyl group).

21. A composition as claimed in claim 19 wherein R8 in the compound of formula IV represents a group of the formula (CH2)n (Va) (n = 2-8)

22. A composition as claimed in claim 19 wherein R6 in the compound of formula IV represents a divalent transition metal selected from Fe", Co", Mn", Zn" and Mo".

23. A composition as claimed in any of claims 18 to 22 wherein each of up to two of R3, R4 and R5 in the compound of formula II or IV represents a group of the formula

(wherein each of R7, which may be the same or different, represents a methyl or ethyl group).

24. A composition as claimed in any of the preceding claims wherein component C) comprises at least one compound selected from

25. A process as claimed in any of claims I to 17 wherein component C) comprises a tetravalent titanium compound corresponding to a compound of formula II or IV as defined in any of claims 18 to 23, taking into account the tetravalence of the titanium.

26. A process as claimed in any of claims I to 17 wherein component C) comprises a compound of formula

wherein each of the groups R8 which may be the same or different, represents an alkyl group having from 2 to 4 carbon atoms, and each of the groups R9, which may be the same or different represents a group of formula VIa, Vlb or VIc as defined in claim 23.

27. A process as claimed in any of claims 1 to 17, 25 and 26 wherein component C) comprises a compound selected from

28. A composition as claimed in any of the preceding claims wherein the percentage weight ratio of components B):A):C) is (10 to 50):(15 to 90):(0.1 to 35).

29. A composition as claimed in claim 28 wherein the percentage weight ratio of components B):A):C) is (15 to 40):(30 to 82):(3 to 30).

30. A composition as claimed in any of the preceding claims additionally containing one or more solvents.

31. A composition as claimed in claim 30 wherein the solvent is selected from aromatic or aliphatic hydrocarbons, esters, ketones, chlorinated hydrocarbons and nitrated hydrocarbons.

32. A composition as claimed in either of claims 30 and 31 wherein the quantity of solvent is insufficient to dissolve components A), B) and C).

33. A composition as claimed in any of the preceding claims additionally containing one or more pigments, dyestuffs, fillers, softeners, stabilisers, wetting agents, dispersing agents, lubricants, flow agents, u.v.-absorbing agents or catalysts.

34. A composition as claimed in claim 33 wherein the weight ratio of the total solids content of components A), B) and C) to any pigments is from 1:0.1 to 1:10.

35. A composition as claimed in claim 34 wherein the weight ratio is from 1:0.5 to 1:5.

36. A composition as claimed in claim 33 additionally containing a catalyst in an amount of from 0.01 to 5% by weight referred to the total solids content of the compositions.

37. A composition as claimed in claim 36 wherein the amount of catalyst is from 0.05 to 1.5% by weight referred to the total solids content.

38. A composition as claimed in claim 1 substantially as herein described.

39. A composition as claimed in claim 1 substantially as herein described in any of the Examples.

40. A method of coating a substrate which comprises applying at least one coating composition as claimed in any of the preceding claims to the substrate and subsequently curing the coating.

41. A method as claimed in claim 40 wherein the coating is cured at a temperature of from 0 to 320"C.

42. A method as claimed in claim 41 wherein the coating is cured at a temperature of from 20 to 1600C.

43. A method as claimed in claim 41 wherein the coating is cured at a temperature of from 200 to 2500C (substrate temperature).

44. A method as claimed in any of claims 40 to 43 wherein a single coating is applied.

45. A method as claimed in any of claims 40 to 44 for the preparation of a matt lacquer wherein the composition additionally contains one or more additional epoxy resins.

46. A method as claimed in claim 40 substantially as herein described.

47. A method as claimed in claim 40 substantially as herein described in any of the Examples.

48. An article coated with a cured coating composition as claimed in any of claims I to 39.

49. A method of adhering two substrate surfaces together which comprises applying a composition as claimed in any of claims 1 to 3q to at least one of said surfaces and bringing the surfaces together.

50. A method as claimed in claim 49 substantially as herein described.