PAINT COMPOSITION BASED ON A CHEMICAL CROSS LINKING SYSTEM AND/OR OXIDATIVE DRYING, WITH LACTATES AS SOLVENT AND THINNER

Abstract: The invention relates to a coating composition based on a chemical hardening system and/or oxidative drying, including a polymer binder for coating compositions; a solvent system, comprising an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent; if desired, further additives, known per se, for coating compositions. The polymer binder is preferably chosen from alkyd resins, polyurethane resins, in particular 2-component polyurethanes, epoxy resins and/or hydroxy acrylate. The solvent system is preferably a mixture of one or more alkyl esters of lactic acid with 1-10, preferably 1-6 carbon atoms, and a volatile aromatic solvent, such as xylene, toluene and Sheelsol A or mixtures thereof. The invention relates in particular to an oxidatively drying paint based on alkyd resin, in the form of a decorative (covering) paint or in the form of a primer, undercoat or masonry paint.

Description: Paint composition based on a chemical crosslinking system and/or oxidative drying, with lactates as solvent and thinner. The present application relates to a decorative coating composition based on a chemical, in particular oxidative, hardening system, which as the solvent contains an azeotrope-forming mixture of at least one lactate compound and at least one volatile organic solvent. More particularly the invention relates to such a coating composition which has a low ozone-producing capacity and a low CO 2 emission to the environment, and at the same time has good technical properties as a paint. The coating composition according to the invention is in particular a coating composition based on alkyd resin. The use of azeotrope-forming mixtures of lactates and organic solvents is known, notably from European Patent 0 676 453 of the applicant. In this, azeotrope-forming mixtures of lactates and volatile aromatic solvents, such as toluene, xylene or "Shellsol A", are used in reversible coating compositions, such as chlorinated rubber paints. Therein, the use of azeotropes of butyl lactate with a volatile aromatic solvent is in particular preferred. The coating compositions described in European Patent 0 676 453 differ from alkyd resins in the following aspect: they are not based on an oxidative crosslinking system, but dry by evaporation of the solvent from the coating applied. Chlorinated rubber paints are reversible, i.e. (the components of) the coating layer applied can be dissolved again by exposure to solvent; when a new top coat is applied, this new coat will merge with the existing coat. This makes chlorinated rubber paints in particular suitable for use as a construction- and/or maintenance finish, for example for the protection and/or coating of iron or concrete substrates of outdoor structures, such as electricity pylons, ships or swimming pools. Chlorinated rubber paints are not manufactured and/or used for decorative purposes. Problems with regard to the appearance of the coating layer applied are therefore of secondary importance when making up chlorinated rubber paints. The international patent application WO 97/08255 (TIKKURILA OY) describes a tinting paste for the tinting of paint products, comprising 2-75% by weight of a pigment component, 10-60% by weight of a thinner in the form of a biodegradable ester of lactic acid and a C,-C 10 alcohol, and a binder component which is soluble in the thinner and which contains a ketone aldehyde resin, a ketone resin and/or an aldehyde resin. It is explicitly mentioned therein that the solvent cannot be an aliphatic alcohol or aromatic hydrocarbon. Furthermore, these tinting pastes are exclusively intended for use in making up the final paint, and are not suitable for any end use, and in particular not for domestic use (such as application with a brush). British Patent 472,249 from 1937 describes a paint for the protection of metal surfaces which as the solvent system contains two or more volatile organic solvents that together with moisture can form a ternary azeotrope on the metal surface. This therefore involves an alcohol/water-azeotrope for removing moisture on or in the substrate and thus preventing hazing caused by moisture. GB 472,249 describes mixtures of benzene and toluene with ethanol or propanol as examples of suitable organic solvents. The use of lactates is neither mentioned nor suggested; nor is it stated that the composition described can be a polymer-based paint. Finally the composition described appears to be a specialized product for professional use in the specifically stated application (protection of metal surfaces), and not a paint for domestic use. US Patent 2,338,948 from 1944 relates to a solvent for chlorinated rubber paints which obligatorily contains p-methylisopropylbenzene (p-cymene). On this subject it is stated in column 1, lines 30-32: "It has now been found that among the aromatic solvents methylisopropylbenzene occupies an unusual position". In "Example 1" a mixture of 92 parts of methylisopropylbenzene and 8 parts of ethyl lactate is described as an example of a suitable p-cymene-containing solvent system. Research by the applicant has shown, however, that p-cymene and ethyl lactate do not form an azeotrope at such a high excess of p-cymene (an azeotrope cannot be observed until the ratio is about 50/50 % v/v = 44.4-55.6 % w/w) and in this ratio is not suitable as a solvent system in the present invention. Moreover, advantages from an environmental point of view will hardly be obtained with such an excess of p-cymene. Furthermore, p-cymene is not a usual or suitable solvent component for paint, and certainly not for domestic paint: it has a very strong smell, is sensitive to light and has an irritating effect on the eyes, skin and respiratory organs, so that preventive measures - including gloves and protective clothing - are prescribed for the use thereof. It is also known to use volatile aromatic solvents, such as toluene, xylene and mixtures of higher-boiling-point aromatic solvents, and mixtures of volatile esters and ketones and aliphatic solvents, as solvents in decorative coating compositions, such as alkyd paints. These solvents dissolve the components of the coating composition well and generally give a good and rapid drying of the topcoat applied. The use of these volatile organic solvents, however, involves considerable disadvantages from an environmental point of view, such as effects on the ozone layer and a high emission of CO 2 . For this reason the various national authorities and supranational bodies are placing more and more restrictions on the use of such volatile organic substances. The paint industry is therefore looking for ways of further reducing the use of these compounds, which are harmful to man and to the environment, in coating compositions. A possible solution to this problem is to replace the volatile organic solvents with solvents or combinations of solvents which cause little or no damage to man and the environment, i.e. solvents with a low ozone-producing potential and or a low emission of CO 2 , and lower toxicity. These solvents must be satisfactory from the technical point of view in paints, however. This means inter alia that they must dissolve the (binder) components of the coating compositions well, and must give a good and rapid drying, without adversely affecting the oxidative drying process. The coating compositions must also not attack (too much) the substrates to which they are applied; they must be compatible with any primer used; the coatings applied must show good durability, in particular when used in the open air; and the coating compositions must show good overpaintability, even on existing, "old" paint layers. It must also be possible to make up the coating composition in such a way that it is suitable for application with a brush, a roller or if necessary a spray gun, both for domestic and for industrial and/or professional use. Finally, for decorative coating compositions, the final appearance (obtained after drying/chemical crosslinking) of the applied coating is of critical importance. It has now been found that such an environmentally friendly coating composition with good paint properties can be provided by using a solvent (system) or thinning system which comprises an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent. The use of such azeotrope-forming mixtures of lactates and organic solvents has not yet been described for chemically, in particular oxidatively, curing paint types, nor for paint for decorative purposes. The invention therefore relates in a first aspect to a coating composition based on a chemical hardening system and/or oxidative drying, comprising 1) a polymer binder for coating compositions; 2) a solvent system, comprising an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent; 3) if desired, further additives, known per se, for coating compositions. The binder component can be any polymer, known per se for coating compositions, which can be chemically hardened by a crosslinking reaction known per se. To this end the polymers themselves can carry suitable crosslinking groups, especially in the side chains, or else be made up with suitable cross-linking components as additives, as will be known to persons skilled in the art. The paint composition can dry oxidatively (i.e. by formation of oxygen bridges), as in compositions based on alkyd resins as the binder. The paint composition can also be cured by another chemical process, however, such as by isocyanate chemistry. Examples of this are compositions based on polyurethane resins, in particular 2-component polyurethanes; epoxy resins; and acrylates, in particular hydroxy acrylate, as the binder. In the invention any alkyd resin, epoxy resin or 2-component polyurethane system known per se can be used as the binder, depending on whether an oxidatively drying paint or a paint hardening in some other way is to be obtained. Resins which are suitable for coating compositions for decorative purposes and/or which are already being used for this purpose in compositions known per se, are prefered. The invention is in particular suitable for making up oxidatively drying coating compositions based on alkyd resins, including long oil ("fatty") alkyd resins, medium oil ("medium fatty") alkyd resins and short oil ("lean") alkyd resins. These can, if necessary, be modified with polyurethanes, silicone, epoxy and similar materials, as will be clear to persons skilled in the art. Examples of suitable alkyd resins, depending on the intended application, are - Long oil alkyd resins based on vegetable oils and/or fatty acids with an oil length of >55% and a P.Z.A. content of 15-30%, e.g. Setal 270 from the Synthese company. Medium oil alkyd resins based on vegetable oils and/or fatty acids with an oil length of 45-55% and a P.Z.A. content of 30-40%, e.g. Nebores 2500 from the Necarbo company. Short oil alkyd resins based on vegetable oils and or fatty acids with an oil length of <45% and a P.Z.A. content of >40%, e.g. Renalyd S 26 from the Condea company. The solvent system comprises an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent. The lactate used is preferably an alkyl ester of lactic acid with 1-10, preferably 1-6 carbon atoms in the alkyl group, such as methyl lactate, ethyl lactate, propyl lactate or butyl lactate, n-pentyl lactate, n-hexyl lactate and all isomers thereof, such as 1 -methyl and 2-methylpropyl lactate, n-butyl lactate, 1-, 2- or 3-methylbutyl lactate and the like. A mixture of two or more of such lactates is preferably used as the lactate component, as indicated in greater detail below. Such alkyl esters of natural lactic acid (L+) are more preferably used, such as those obtained from the fermentation of sugar. The organic solvent can be any usual organic solvent (notably from petrochemistry) for solvent-borne coating compositions, such as volatile aromatic solvents (toluene and xylene and commercially available mixtures, such as Shellsol A and Solvesso 100), and volatile oxygenated solvents, such as esters and ketones (acetone, ethyl acetate and the like), or combinations of these solvents with each other or with other organic solvents, with possible tertiary systems being obtained. Of these solvents, volatile aromatic solvents, and especially xylene, toluene and Shellsol A, are in particular preferable. The volume ratio between the total of the lactate components and the total of the organic solvents is preferably in the range from 95/5 to 70/30, in particular in the range from 90/10 to 80/20. This ratio is usually lower than the ratio which is used in the chlorinated rubber paints of European Patent 0 676 453, where mixtures of 60/40 and 50/50 can be used. The content of organic solvent (other than the lactate) is preferably not higher than 20%, preferably lower than 12.5%, relative to the total coating composition. The solvent mixture used, as well as the ratios of the components therein, are such that the components of the solvent evaporate as an azeotropic mixture, without separation occurring. The formation of such an azeotrope can be determined experimentally in a simple way; for this, and also for further information about the azeotropic lactate mixtures and the advantages thereof, the reader is referred to the abovementioned European Patent 0 676 453, the contents of which have been incorporated herein by such reference. The coating compositions according to the invention can furthermore include all additives known per se for decorative coating compositions, in particular alkyd paints, for which the reader is referred to the known reference books. Examples of such additives are: Organic and inorganic pigments, such as phthalocyanine blue, carbon black and titanium dioxide white, Anti-rust pigment such as zinc phosphate, - Fillers such as silicates, carbonates and silicas, Wetting agents such as non-ionogenic and ionogenic wetting agents, Stabilizers such as bentonite, silicas and calcite, Adjuvants such as siccatives, anti-skinning agents and UV absorbers, as well as extenders, crosslinking agents and other additives known per se; which are used in known quantities in a manner known per se. It may also be advantageous according to the invention also to include drying agents, with lactate salts, including lactate salts of iron, calcium, zinc or other suitable metals, being preferable in particular. The coating compositions can be made up in a manner known per se, i.e. by dissolving the binder and the other components in the solvent system. The solvent system according to the invention will be used analogously to known solvent systems, in quantities known per se. This can be carried out simply by, compared to the known coating compositions, replacing the solvent with the azeotrope-forming mixture according to the invention when formulating. The coating compositions according to the invention can be made up for example by diluting the binders, i.e. the alkyd resins obtained from the polymerization, with the solvent systems according to the invention, with a part of the quantity of solvent which is eventually required in the final paint. The quantity of solvent can then be made up to the quantity required for the end use, and at the same time the other components of the paint can also be added. This can be carried out during the final production (formulation), after which the paint composition is put into the container in which the final product so obtained is sold. The coating composition according to the invention can be made up for any intended end use, and in particular as a decorative covering paint for both professional and domestic use. The composition can also be made up as an undercoat, primer or masonry/wall paint, however. When it is made up, the viscosity and other rheological properties of the paint should preferably be adjusted in such a way that the paint is suitable for application with a brush, a roller or if necessary a paint spray, as will be known to persons skilled in the art. In a final coating composition the solids content (i.e. binder plus solid additives) will make up 20-80%, preferably 40-65% of the total composition, while the remainder (up to 100%) will be formed of solvent (i.e. the azeotropic mixture) and any other liquid components present. The solvent system can if necessary also be used for making up so-called "high solid" coating compositions, i.e. compositions with a solids content of 85% or more. Solvent-free systems, on the other hand, have considerable disadvantages, in particular for decorative paints for domestic use. Thus they are not suitable for brush paints, as they are too highly viscous and dry too quickly to be applied effectively. Although the presence of traces of water cannot be excluded, the coating composition according to the invention is in particular a solvent-borne coating composition, i.e. the composition contains in essence no or virtually no water as solvent (less than 5%, preferably less than 1%, relative to the solvent mixture). A suitable composition of the final paint is for example: - binder: 20-50% by weight - solvent system 20-50% by weight including: lactates 18-42% by weight org. solvents 2-8 % by weight - colorants and pigments 4-30% by weight - fillers 10-30% by weight - other additives 1-5 % by weight, with the whole of the constituents forming 100% by weight. The coating compositions according to the invention offer considerable advantages from an environmental point of view. Thus they contain a relatively small quantity of aromatic solvents, have a low stability in the atmosphere and therefore have a lower ozone-producing capacity, and they do not cause any extra CO 2 emission to the environment, as the lactates used are obtained from agricultural products. Lactates are also biodegradable. Furthermore, the use of lactates also offers considerable advantages in the handling by the end user, especially with regard to safety. Thus the lactates - some of which are permitted for use in foods - are less toxic and/or caustic than ordinary aromatic solvents and/or terpentine. This is in particular of importance in coating compositions for domestic use. All the coating compositions according to the invention also offer good technical properties as paints. Thus they give good and rapid drying, without the crosslinking of the alkyd resin being disturbed. They also show good outside durability and are in particular suitable for domestic use, such as application with a brush. In research by the applicant it has been found that, in particular in the case of alkyd paints, especially favourable technical properties as paints are obtained when a mixture of at least one alkyl lactate with 1-3 carbon atoms in the alkyl group, and at least one alkyl lactate with 4-6 carbon atoms in the alkyl group, is used as the lactate component in the azeotrope-forming solvent system. In particular, mixtures of methyl or ethyl lactate, on the one hand, and n-butyl, 1- butyl or n-pentyl lactate, on the other hand, and especially mixtures of methyl lactate and n-butyl lactate, have been found to be very suitable. In these mixtures the C,_ 3 lactate (where C n indicates the number of carbon atoms in the alkyl group) is preferably used in a quantity of 40-95% by weight, preferably 55-75% by weight, relative to the total of the lactate components. More preferably, a mixture of methyl lactate and n-butyl lactate in a ratio of about 1.5:1 to 3:1, especially about 2:1, is used. By means of the present description, a person skilled in the art will be able to determine the optimal ratio of the C,. 3 lactate, the C 2 . 4 lactate and the organic solvent for obtaining the best technical formulation as a paint. In longer oil alkyd resins relatively more methyl lactate will be used relative to the quantity of butyl lactate and organic solvent. The use of the above azeotrope-forming mixtures of methyl lactate/butyl lactate and organic solvent offers inter alia the following advantages: These ternary mixtures show a better dissolving capacity, compared with mixtures of butyl lactate and organic solvent alone, such as the preferred mixtures according to European Patent 0 676 453. This dissolving capacity is in particular of importance in making up the alkyd resin components which are per se solid and as a rule moderately soluble. The tenary azeotropes show a better drying behaviour than mixtures of butyl lactate and xylene, and give a good film formation. Mixtures of butyl lactate and xylene usually have too inhibitory an effect on film formation for use in decorative coating compositions, in particular alkyd resins. Mixtures of butyl lactate and organic solvents may be too aggressive for application on sensitive substrates, such as plastics. Mixtures of butyl lactate and organic solvents may also blister when they are applied on an undercoat or for the overpainting of an existing coat. Mixtures of methyl lactate/butyl lactate and organic solvent are less aggressive and thus better for overpainting. It has also been found that mixtures of methyl lactate/butyl lactate and organic solvent give a better appearance of the coating compositions applied. As has already been mentioned, this is not a problem with the known chlorinated rubber paints, which are mainly used for construction purposes. In particular it has been found that mixtures of methyl lactate, butyl lactate and organic solvent give a considerably better gloss than mixtures of butyl lactate and organic solvent alone. It has been found that paint mixtures based on butyl lactate and organic solvents sometimes show a "gloss haze" and that the gloss can decrease after application. As a result it may be difficult in practice to make up the commercially very desirable "high gloss" paints on the basis of mixtures of butyl lactate and organic solvents alone. This has been found to be quite possible, however, with the above ternary azeotropes. Although the invention is not limited to a specific explanation, the better properties of the ternary azeotropes are probably due to the better, more uniform and faster evaporation, compared with the twofold mixtures of butyl lactate and organic solvent. The final coating compositions can be used analogously to the known chemically hardening, in particular oxidatively drying, coating compositions, i.e. they are applied to the substrate, after which curing takes place on the one hand by evaporation of the solvent present and on the other hand by the crosslinking reaction. As a result the final coating layer, unlike reversible coatings of chlorinated rubber paints, will after crosslinking no longer be soluble in the solvent system used. The compositions according to the invention are therefore non-reversible, and differ essentially from reversible paints in this respect: reversible paints dry by evaporation of the solvent, with other mechanisms having essentially no or only a subordinate role. When a coat of paint applied is again brought into contact with the evaporated solvent, the dry film of paint dissolves again and essentially the original paint is obtained again. In the case of chemically crosslinking paints, evaporation of the solvent also takes place, but in addition there is also a change in the chemical structure of the polymer components for example by oxidation (oxygen uptake) or by crosslinking with a hardening component such as an isocyanate or amine hardener. When such a chemically hardened dry film of paint is brought into contact with the original solvent again, the film of paint no longer dissolves, as the binder (polymer) has been changed in structure and - as a result - has become insoluble for the original solvent. In further aspects the invention concerns the application of an azeotrope- forming mixture of at least one lactate compound and at least one organic solvent as a solvent system for coating compositions based on chemical hardening systems and/or oxidative drying, in particular coating compositions as described above; as well as a method for the production of a coating composition based on a chemical hardening system and/or oxidative drying, in particular as described above, comprising the dissolving of a polymer binder for coating compositions, as well as any other additives, in an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent. The azeotrope-forming solvent system is preferably as described above. The invention will now be explained by the following non-limiting examples. Example 1: Determination of azeotrope-forming capacity. The phenomenon is often observed where by mixing two or more solvents with higher boiling points a mixture is obtained which has a lower boiling point or a higher vapour tension. This synergistic effect often occurs when the surface of a film of paint develops a haze because of the presence of small quantities of water. A solvent with a good solubility can thus also have a low evaporation rate. The consequence of this is then a surface disturbance and possibly also a negative effect on drying. In accordance with the principle of azeotropic technology, during evaporation a rapidly evaporating solvent can take a slowly evaporating solvent with it and evaporate it. The rate of the evaporation can of course be adjusted, depending on the application and the optimal appearance of the film of paint. a. Determination for a twofold azeotrope mixture The azeotrope formation between two potential solvents has been investigated in detail. For this purpose five different weight and volume ratios, namely 80/20, 60/40, 50/50, 40/60 and 20/80, of for example solvent A and solvent B were weighed out in seven 25 ml graduated cylinders. In addition, two extremes, i.e. 100% solvent A and 100% solvent B, were included as references in the experiment. These graduated cylinders were placed in a fume cupboard with forced ventilation. The level of the mixtures in the graduated cylinders was monitored daily and the evaporation trend was closely observed all the time. The mixtures left were also repeatedly weighed. After 5 days the graduated cylinders were taken out of the fume cupboard and the weight of the solvent left was determined. In addition, the evaporation rates during the first few days were also noted down. The possible azeotrope formation between the solvents was determined by means of the results obtained. b. Determination for a triple azeotrope mixture After determination of the azeotrope formation between two tested solvents, the possible formation of an azeotrope between these mixtures with a third solvent was investigated. The azeotrope mixture of these two solvents was thus mixed in the various weight ratios with the third solvent, as has already been described previously in the case of the method of the twofold azeotrope mixture. The triple azeotrope mixture must eventually in its entirety show a higher evaporation rate or a lower boiling point, as the case may be, than the separate solvents. c. dissolving capacity The azeotropy experiment described herein relates to the azeotrope formation of aromatic or oxygenated hydrocarbons with solvents which have latently less photochemical ozone-forming potential (PCOP), or make little or no extra contribution to CO 2 levels (greenhouse effect) and in addition have a good dissolving capacity. The only solvents eligible here are those which in the first instance show adequate solubility for certain applications. Because of the need for a greater dissolving capacity for the short oil alkyd resins, azeotrope mixtures with a better dissolving capacity are initially used. The third solvent (e.g. a lactate ester) with less dissolving capacity/higher vapour tension is not added until after the incorporation of other ingredients of the recipe. This quantity largely depends on the intended application. A good balance should be sought between these two important properties, i.e. deviation from the correct ratio of the solvents in the azeotrope mixture and the corresponding dissolving capacity. The medium oil and long oil alkyd resins can dissolve more easily compared with the short oil alkyd resins. It should therefore be possible better to maintain the ratio of solvents in the azeotrope mixtures. In the calculation of ratios in the azeotropy experiment, allowance is generally made for a surplus of aromatic solvents used as a medium in the polymerization reaction during manufacture of the binder. Example 2: Instructions for the production of the paint compositions. After curing in the binder factory the alkyd resins are dissolved in part of the azeotrope mixture. In the production of paints, stabilizers, fillers, pigments etc. are added to the alkyd resins, and then the azeotrope mixture as required. The milling paste is dispensed to a prescribed temperature and/or the required fineness. If the fineness has not been attained, the mixture is milled in a Dyno mill, in accordance with the prescribed operational conditions, such as temperature and pressure. The milling paste is then finished with residual alkyd resin, adjuvants and residual azeotrope mixtures and/or lactate. The viscosity, density, fineness and drying time of the sample are measured at the prescribed temperature and relative humidity, and the viscosity of the batch is then adjusted with residual azeotrope mixture or lactate. Example 3: Production of a high-gloss paint based on a long oil alkyd resin. A high-gloss paint based on a long oil alkyd resin was made up as described in Example 2, with the following composition (in per cent by weight up to 100%): Long oil alkyd resin about 100% 41.2 Stabilizer 0.3 Pigment 30.5 Adjuvants 0.8 Azeotrope mixture 27.2 including: lactates 25 J org. solvent 2J Example 4: Production of an anti-rust primer based on a medium oil alkyd resin. An anti-rust primer based on a medium oil alkyd resin was made up as described in Example 2, with the following composition (in per cent by weight up to 100%): Medium oil alkyd resin about 100% 21.5 Stabilizer 1.0 Wetting agent 0.2 Pigment 13.7 Anti-rust pigment 12.0 Fillers 22.8 Adjuvants 0.6 Azeotrope mixture 28.2 including: lactates 25.9 org. solvent 2.3 Example 5: Production of a quick-drying gloss paint based on a short oil alkyd resin. A quick-drying gloss paint based on a short oil alkyd resin was made up as described in Example 2, with the following composition (in per cent by weight up to 100%): Short oil alkyd resin about 100% 34.3 Stabilizers 0.6 Wetting agent 0.5 Pigment 20.2 Adjuvants 1.2 Azeotrope mixture 43.2 including: lactates 36.3 org. solvent 6.9

Claims: CLAIMS 1. Coating composition based on a chemical hardening system and/or oxidative drying, comprising 1) a polymer binder for coating compositions; 2) a solvent system, comprising an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent; 3) if desired, further additives, known per se, for coating compositions. 2. Coating composition according to Claim 1, wherein the polymer binder is chosen from alkyd resins; polyurethane resins, in particular 2-component polyurethanes; epoxy resins; and/or hydroxy acrylate. 3. Coating composition according to Claim 1 or 2, in the form of an oxidatively drying paint based on alkyd resin, in particular based on a long oil alkyd resin, a medium oil alkyd resin and/or a short oil alkyd resin, which is, if necessary, modified with polyurethanes, silicones, epoxy and/or similar materials. 4. Coating composition according to one of the preceding claims, wherein the lactate component in the solvent system includes at least one alkyl ester of lactic acid with 1-10, preferably 1-6 carbon atoms in the alkyl group. 5. Coating composition according to one of the preceding claims, wherein the lactate component in the solvent system includes a mixture of at least one alkyl lactate with 1-3 carbon atoms in the alkyl group and at least one alkyl lactate with 4-6 carbon atoms in the alkyl group, in particular a mixture of methyl lactate and n-butyl lactate. 6. Coating composition according to Claim 5, wherein the alkyl lactate with 1-3 carbon atoms in the alkyl group makes up 40-95% by weight, preferably 55- 75% by weight, of the total of the lactate components. 7. Coating composition according to one of the preceding claims, wherein the organic solvent is chosen from volatile aromatic solvents, in particular xylene, toluene and Shellsol A, or mixtures thereof. 8. Coating composition according to one of the preceding claims, wherein the volume ratio between the total of the lactate components and the total of the organic solvents is in the range from 95/5 to 70/30, in particular in the range from 90/10 to 80/20. 9. Coating composition according to one of the preceding claims, wherein the organic solvent content is lower than 20%, and is preferably lower than 12.5%, relative to the total coating composition. 10. Coating composition according to one of the preceding claims, which in addition contains one or more drying agents, in particular chosen from lactate salts of metals, such as the lactate salts of iron, calcium or zinc. 11. Coating composition according to one of the preceding claims, in the form of a decorative paint, in particular a decorative covering paint, or in the form of a primer, undercoat or masonry paint. 12. Coating composition according to one of the preceding claims, and in particular according to Claim 11, made up for application with a brush, a roller or a paint spray. 13. Application of an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent as a solvent system for coating compositions based on chemical hardening systems and/or oxidative drying, in particular coating compositions according to one of Claims 1-12. 14. Method for the production of a coating composition based on a chemical hardening system and/or oxidative drying, in particular according to one of Claims 1-12, comprising the dissolving of a polymer binder for coating compositions, as well as any other additives, in an azeotrope-forming mixture of at least one lactate compound and at least one organic solvent. 15. Method according to Claim 14, wherein a binder obtained from the polymerization is first diluted with part of the total quantity of azeotrope-forming solvent which is eventually required in the final paint, after which the remainder of the solvent is added before or when the coating composition is put into the container, at which point the other components of the composition can also be added. 16. Method for the coating of a substrate, comprising the application to the substrate of a coating composition according to one of Claims 1-12, in particular with a brush, a roller or a spray. 17. Substrate coated with a coating composition according to one of Claims 1- 12, or obtained by the method of Claim 16.

Inventors: BAKKER HENDRIK ROELOF, KRANZ MICHAEL THEODORUS CHRIST, BAKKER, HENDRIK, ROELOF, KRANZ, MICHAEL, THEODORUS, CHRISTIANUS
Applicants: BAKKER HENDRIK ROELOF, BICHEMIE COATINGS BV, KRANZ MICHAEL THEODORUS CHRIST, BAKKER, HENDRIK, ROELOF, BICHEMIE COATINGS B.V., KRANZ, MICHAEL, THEODORUS, CHRISTIANUS
Application year: 1998
Main classification: C09D7
IPC codes: C09D7