MXPA99004969A - Aglutinant for composition of revestimie - Google Patents

Abstract

A binder for a coating composition is capable of being obtained as the reaction product of a carboxyl-terminated fatty acid ester with an ethylenically unsaturated carboxylic acid and an ethylenically unsaturated carboxylic acid ester. The carboxylic fatty acid ester is produced by the reaction of a self-oxidizable fatty acid and a polyol, modified to introduce at least one terminal carboxyl group. The reaction is optionally carried out in an organic solvent that is removed essentially at the end. The material is neutralized with a base to make it soluble in water. Thixotropy can be provided by a final reaction step of amine / (poly) isocyanate to neutralization before

Description

"AGLUTINANT FOR COATING COMPOSITION" The present invention relates to a water reducible binder for use in aqueous structured coating compositions such as paints and lacquers. Air drying coatings carried in solvent on substrates such as wood and metal have been used for many years. In general, they are used both to provide protection to the substrate and to provide an aesthetically pleasing appearance. Depending on the nature of the polymeric binder used in the final coating, these decorative air drying coatings can be applied to both interior and exterior surfaces. For both consumer and professional applications, the predominant organic solvent is conventionally an aliphatic hydrocarbon such as mineral turpentine, containing about 18 percent aromatic materials. More recently, mineral turpentine has been replaced by aromatic analogs that have the benefit of reducing the toxicity of the solvent and at the same time reducing odor. Other organic solvents such as esters and ketones are often present in small amounts, usually additives such as desiccants, fungicides and dyes. Despite the progress toward less toxic and less odorous solvents, the fact that organic solvents are used, still results in their evaporation into the atmosphere after application, thus contributing to air pollution. A reduction in the level of the volatile organic solvents used in decorative coatings is therefore considered desirable, of course necessary. The development of high solids paints with much lower levels of organic solvent would have a significant impact on air pollution. However, the introduction of these products has been delayed due to the lack of laws and their price is relatively higher. An alternative to organic solvent as a mobile carrier for resin, pigment, etc. is the water. Decorative water-based coatings have been available for many years and the most common types are usually formulated in thermoplastic (co) polymers derived from monomers such as vinyl acetate, vinyl acetate / Veova, vinyl acetate copolymers / ethylene, styrene, styrene / methylacrylates. In these cases, the polymer is formed by polymerization by - - emulsion in the aqueous phase, to produce an emulsion with dispersed discrete particles. The polymers formed by this process usually have a very high molecular weight. In order for the coatings to be formed from these polymers, the particles must coalesce to form a coherent resistant film. Due to the nature of the polymerization process, the water-sensitive materials remain in the thermoplastic coating. Resins carried in air-dried water have also been available for many years. These can be alkylated with high acid value. Traditionally, this acidity has been achieved by ring breaking of the trimellitic anhydride by reaction with a hydroxyl-terminated alkyd. The alkyd can then be diluted to about 70 percent to 80 percent in a water-miscible organic solvent, such as butyl glycol and neutralized with ammonia or amine, to be the product dilutable in water. These materials have never achieved commercial success in the decorative paint market due to the high solvent content and poor application and performance properties. Alkyd emulsions are another way to produce decorative coatings based on water. It is reasonable to assume that these will retain their oxidative nature and therefore, they will reticularize after application. However, they have not had great commercial success in decorative paints and varnishes, due to problems related to operation, such as yellowing, drying, desiccant stability, water resistance and poor rheology. Therefore, there is still a need for a self-oxidizable binder for waterborne coatings that can produce finished coatings with higher abrasion and / or hardness resistance, which are preferably also faster drying and in the case of the resins of high acid content known, containing less organic solvent. A preferred sub-class of binders according to the invention comprises those which result in thixotropic coating compositions. Therefore, it is convenient here to review the prior art related to the thixotropic system. Solvent-based coatings widely used in the domestic consumer market are generally thixotropic in appearance. That is, the painting exhibits recovery that depends on time. In the unaltered state at low shear rates, these coatings which may be paints, varnishes or dyes have a high apparent viscosity. Viscosity at - - Current low shear stress will depend on the degree of shear structure, but a typical non-drip coating, the viscosity at low shear stress would be in the order of 1,000,000 Pa.s. This has the effect of making the coating similar to a jelly in the unaltered state in the can, before application. At high shear rates typically those experienced when the paint is applied by brush, the paint will exhibit the viscosity characteristics of a liquid paint thus allowing easy application. Once the brush application is stopped, the paintings will show a recovery in viscosity and structure over time. This will allow the paints to flow and level over the sub-strand without warping, thus providing a coating that is uniform in thickness and virtually free of brush marks or signs. This thixotropic character can be conveniently measured using a constant stress rheometer and carrying out an oscillation recovery sweep. The measured parameters are the elastic modulus G 'and the viscous modulus G ". Immediately after applying a cutting force, the viscous modulus will dominate and the paint will flow. As time goes by, both G 'and G "show an increase. With a thixotropic material, the - - The rate of increase in the elastic modulus will be faster than G "and will eventually counteract the viscous modulus at which time the product can be considered as being of a more solid nature that will no longer warp. Any product that after a period of time after applying a shear force will show a curve in which G 'increases to a faster rate of G "may be considered thixotropic. True thixotropic solvent-based coatings widely available in the domestic consumer market are usually based on self-oxidizing binders that have been chemically modified by polyamide technology or urethane / urea technology, as described in Patent Number GB- A-1,454,388 and Patent Number GB-A-1, 454, 414. Other known means for imparting the structure in solvent-based coatings, which are not truly thixotropic, is by means of clays, silicas, amide additives, additives of hydrogenated resin oil. The water-based binders described above whether they are thermoplastic emulsion (co) polymers or alkyd emulsions, which are widely used in the domestic decorative market, are not inherently thixotropic. Any structure that - have these materials, is imparted by the addition of additives from the paint manufacturing stage and not by chemical modification of the binder itself. There have been other proposals for thixotropic systems that are aqueous, for example, using the binder disclosed in Patent Number GB-A-2, 237, 576. It is based on an acrylic polymer having hydroxyl and carboxylic acid suspended groups. This polymer material is made thixotropic by reaction with an isocyanate having at least two isocyanate groups, an amine having at least two amino groups and a primary or secondary monoamine. However, even when these polymers are dispersed in water, their capacity for post-curing and therefore their final film performance is limited. Thus, to date, a need remains for a commercially viable water-based coating system, and in particular a binder therefore, which system can be produced in thixotropic or non-thixotropic form, as required. The present invention now provides a binder for a water-based coating composition, the binder being able to be obtained as the product of a reaction mixture comprising: a) a carboxy-terminated fatty acid ester obtainable as the reaction product of an acid self-oxidising fatty acid and a polyol, followed by a reaction to fix a carboxy group, b) an ethylenically unsaturated carboxylic acid, and c) an ester of an ethylenically unsaturated carboxylic acid. The binders according to the present invention are suitable for incorporation into waterborne coating compositions such as (depending on the specific binder in question) paints, lacquers, varnishes or dyes. In its broadest definition, the present invention encompasses binders for water borne coatings that result in non-thixotropic compositions, those that result in thixotropic compositions and those that are precursor binders. (that is, capable of becoming) that result in thixotropy. In addition, the binders of any of the above-mentioned classes per se can be provided in neutralized form, ready for use in the manufacture of coating compositions or in non-neutralized form for neutralization by the manufacturer. The - - invention also encompasses coating compositions containing any of these compositions. The binders of the present invention cause the final composition to be air-dried because they are obtained from a self-oxidising fatty acid that has been esterified with a polyol and then terminated with a carboxy group. The binders according to the present invention, whether or not they produce thixotropy when incorporated into the final coating product, rely on one or more operating advantages compared to compositions carried in water based on conventional binders. These advantages are selected from one or more of higher abrasion resistance, increased hardness, faster drying and the need for less amount of organic solvent in the final reaction mixture. However, coatings intended for application other than as floor coatings require some degree of rheological control to provide suitable application properties in terms of flow, leveling and bending control. This is usually achieved in solvent-based coatings by the use of thixotropic binders or by the use of thixotropic additives that are added during the paint manufacturing process. Preferably, in order to provide a thixotropic water-based coating, the binders according to the present invention are modified in such a way that they become thixotropic, (ie, they confer thixotropy in the final coating compositions) without the use of other external additives. In these cases, the resulting products will not necessarily be truly soluble in water. This modification to provide thixotropy in the final product is obtained by producing a precursor material which is capable of being obtained when a functional hydroxy monomer material is included in the reaction mixture with reagents (a), (b) and (c). The precursor is then converted to a thixotropic binder by reaction with at least one amine, followed by reaction with an isocyanate material. The water-reducing capacity of the final product can be achieved by neutralizing with an appropriate base, for example, one or more materials that are selected from ammonia, primary, secondary and tertiary amines and alkali metal hydroxide. Suitable amines include triethylamine, diisopropylamine, triethanolane, dimethylethanolamine and morpholine.

With respect to the starting materials, the modified self-oxidizable fatty acids are known. Typical self-oxidizing fatty acids are the unsaturated fatty acids which are known as "drying oils" and are found in various mixtures in natural substances such as soybean oil, sunflower oil or safflower oil, eg, oleic, linoleic and linoleic acids. For example, 9, 12-octadecanoic acid is a constituent of soybean oil, and sunflower oil. These acids that have at least two double bonds, which do not have a methylene bond between them (it is decri, the conjugated fatty acids) are preferred for faster drying. The most useful examples have 15 to 24 carbon atoms. The carboxyl-terminated polyol esters of these acids are conveniently prepared by a first reaction step starting with the fatty acid and a polyhydric alcohol. The fatty acid ester undergoes a second reaction step to yield the carboxy-terminated fatty acid ester that preferably contributes from 20 percent to 80 percent of the weight of the resulting binder., either unmodified or in the neutralized and / or thixotropically modified form, which will be explained in more detail below. Preferably, the fatty acid ester of the first step (non-carboxylated) is formed by reacting the fatty acids with polyhydric alcohols, e.g. at a temperature of 200 ° C to 250 ° C to an acid number of between 0 and 10 milligrams of KOH per gram, preferably to less than 5 milligrams of KOH per gram. Suitable vegetable oil fatty acids include unconjugated or conjugated mixtures of both. Suitable examples of the unconjugated acids include linoleic acid, linolenic acid, resin oil fatty acids, flaxseed fatty acids, soybean fatty acids and sunflower fatty acids. Suitable examples of conjugated fatty acids include dehydrated castor oil fatty acid, the UKD products supplied by Henkel such as UKD3510 and UKD6010 and the products of Unichema PRIFAC7967 and 7968. The fatty acid is esterified with one or more polyhydric alcohols containing two or more hydroxyl groups per molecule. Typical examples include 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, di-trimethylolpropane and di-pentaerythritol. The resulting fatty acid ester contains an excess of hydroxyl groups, preferably yielding a product with a hydroxyl number of between 10 and 100 milligrams of KOH per gram, preferably between 20 and 70 milligrams of KOH per gram.

After the reaction of the fatty acid and the polyol, a subsequent reaction is carried out to fix at least one carboxylic acid group. This is conveniently effected by reaction with carboxylic acid anhydride such as trimellitic anhydride (TMA), allelic anhydride, italic anhydride, tetrahydrophthalic anhydride, or pyromellitic anhydride, or a mixture of any or more thereof. The final acid value of the carboxylated fatty acid ester is from 10 to 100 and more preferably from 20 to 70 milligrams of KOH per gram. In a preferred embodiment of this first reaction step, the fatty acids and polyols are charged to the reactor and heated to a maximum temperature of 250 ° C. stirring the water until the acid number decreases to less than 10 milligrams of KOH per gram, preferably to less than 5 milligrams per KOH per gram. The resulting fatty acid ester is then cooled to 170 ° C and TMA is added. The mixture is maintained at 170 ° C until the TMA ring rupture has occurred, yielding a product with an acidic value of between 10 and 100 milligrams of KOH per gram preferably between 20 and 70 milligrams of KOH per gram. The next step in the process is then to copolymerize the ethylenically unsaturated acid and the ester monomers in the presence of the carboxy-terminated fatty acid ester. These monomers preferably comprise acrylic acid and / or methacrylic acid together with one or more esters of acrylic acid and / or one or more esters of methacrylic acid. Suitable esters of acrylic or methacrylic acids are those containing from 1 to 12 carbon atoms such as methyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, til (meth) acrylate, ethylhexylacrylate, glycidyl ( met) acrylate, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate. Preferred examples are methyl methacrylate, butyl methacrylate, butyl acrylate, hydroxyethyl methacrylate and methacrylic acid mixed in appropriate ratios. Preferably, an "equivalent" polymer formed only by polymerization of reactants (b) and (c) and optionally, any additional ethylenically unsaturated monomer (s) (see below) in the same amounts as in the binder in accordance with present invention has the glass transition temperature from 263 ° K to 373 ° K, preferably from 273 ° K to 343 ° K. It is necessary to employ both the ethylenically unsaturated carboxylic acid and the unsaturated carboxylic acid ester. The first is necessary to incorporate the required acid functionality. The last one is necessary to ensure the hardness of the coating - - final. The ester does not necessarily have to be an ester of the same ethylenically unsaturated acid which is incorporated in the acid form per se. Mixtures of different acids and / or different esters could be used. Generally, the acid to ester ratio is preferably 0.1: 1 to 0.22: 1 by weight. It is preferred to include in the reaction mixture with the carboxyl-terminated fatty acid ester, the ethylenically unsaturated carboxylic acid and the ester of an ethylenically unsaturated carboxylic acid, an additional ethylenically unsaturated monomer component comprising one or more monomers. suitable ethylenically unsaturated such as vinyl toluene or styrene or one of its derivatives (such as alpha-methylstyrene). Of course, mixtures of these other unsaturated monomers can also be used. These additional unsaturated monomers can provide additional benefits such as hardness and durability. The selection of the specific monomers for the total mixture depends on a number of factors but especially on the final requirements of the application and operation of the polymer, including the aforementioned acid number of 20 to 75 milligrams of KOH per gram, but more preferably from 35 to 70, to allow neutralization, before being diluted in water.

This reaction is preferably carried out in the presence of an organic solvent in order to facilitate the manufacture and handling capacity of the finished product, before being diluted with water. The selection of the organic solvent for this step can be a miscible solvent in water that will still be present and will in fact be required, to remain in the final neutralized resin and diluted with water. Alternatively, the solvent for this step may be one that simply acts as a means for addition polymerization and that will be removed after this stage of the process. In this case, an addition of a water-miscible co-solvent will be required before neutralization and dilution with water. In any case, it is preferred that the solvent (if used) in this step does not contain any labile hydroxyl groups, since these will esterify with the carboxyl groups present in the monomer mixture and / or the fatty acid ester. When a solvent containing hydroxyl is used in the final product, then a non-reactive solvent such as xylene or toluene can be used, this being removed after the addition polymerization. When the addition of the carboxylic acid group is complete (e.g., by a ring breaking reaction with a corresponding anhydride), the product is cooled to an appropriate temperature. This temperature is determined by the nature of the carrier solvent and the selection of the polymerization catalyst. Preferably, the solvent is added at a level of 20 percent to 50 percent, which is calculated on the weight of the total reaction mixture. In a typical reaction, a mixture consisting of ester monomers and ethylenically unsaturated acid is prepared and a polymerization catalyst is also added. Preferably, this mixture is added to the carboxy-terminated fatty ester solution over a period of 2 to 8 hours. Typically, the temperature of the reaction can be between 70 ° C and 170 ° C, preferably between 110 ° C and 140 ° C. Typical polymerization catalysts are di-tertiary butyl peroxide, tertiary butyl perbenzoate, tertiary butyl octoate, tertiary di-amyl peroxide, dicumyl peroxide and 1,1-bis (tertiary butyl peroxy) cyclohexane. After the monomers have been added, the resin is preferably kept at this temperature until the polymerization is complete. If necessary, additions of the polymerization catalyst can be made to ensure complete conversion.

When the reaction is complete, a part of the process solvent is removed, preferably by vacuum distillation. If the processing solvent is the same as that desired in the final resin, then a sufficient amount is removed to provide a non-volatile content (NVC) of 70 percent to 95 percent by weight, preferably 75 percent by weight. one hundred to 95 percent. If an intermediate processing solvent such as xylene is used, then essentially all of this is removed, and the preferred water-miscible solvent is added to provide a non-volatile content of 70 percent to 95 percent, preferably 75 percent. one hundred to 95 weight percent resin. To avoid any doubt, in the context of the present invention, the term "essentially all is removed" means that afterwards, the content of the non-volatile substance of the mixture is more than 90 weight percent, preferably more than 95 percent by weight, and especially more than 98 percent by weight. Suitable examples of water-soluble solvents include any alcohol, glycol ether, glycol ether ester or a mixture of these solvents. Examples are, but are not limited to propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, butyl glycol, propylene glycol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether , propylene glycol dimethyl ether and N-methylpyrrolidone. The water-reducing capacity can be conferred by the neutralization of the resin before the addition of water as described above. This is done by adding ammonia or amines such as triethylamine, diisopropylamine, triethanolamine, dimethylethanolane or morpholine. As mentioned above, to induce thixotropy in the final product, a precursor is made by including a functional hydroxy material in the reaction mixture of (a), (b) and (c) and this precursor is then made reacting with at least one amine (preferably a monoamine or diamine or mixture thereof) followed by reaction with an isocyanate (either a monofunctional or polyfunctional isocyanate or a mixture thereof). In a preferred embodiment, the precursor resin in solution (preferably in an organic solvent) is heated and then reacted preferably with a mixture of mono and di-amines. The further reaction of the amine salts produced in this way is then carried out by the introduction of polyisocyanate-containing materials. After the complete reaction of the amine groups, additional amine is added to react with residual carboxylic acid groups - - of the polymer. Finally, the reaction mixture is diluted with water to provide a thixotropically modified binder dispersible in water. Examples of suitable mono- and di-amines include (but are not restricted to) ammonia, diethylamine, triethylamine, morpholine, 4-ethylmorpholine, ethanolamine, dimethylaminopropylamine, diethanolamine, methyl diethanolamine, ethylenediamine, hexamethylenediamine and m-xylene diamine. . Suitable examples of suitable functional isocyanates include but are not restricted to) methyl, ethyl, cyclohexyl and phenyl isocyanates and the reaction product of toluene diisocyanate and a monofunctional alcohol such as ethanol, butanol, cyclohexanol, tridecanol or butyl glycol. Suitable polyfunctional polyisocyanate materials include (but are not restricted to) isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, proprietary material such as diisocyanate dimer of 'hexamethylene sold as Tolonate HDB and a trimer of diisocyanate • of hexamethylene sold as Tolonate of HDT both produced by Rhone Poulenc.

- It is desirable that there is a slight excess of amine relative to the isocyanate groups. The ratio of isocyanate to amine groups for example can be from 0.9: 1 to 1: 0.9, but preferably is less than or equal to 1: 1. The resins produced can be converted into coatings by the addition of pigments, diluents, deicers, fungicides, antioxidants and other additives that are well known in the industry. The resins described can also be converted into clear varnishes. The present invention will now be explained in more detail by the following non-limiting examples.

Examples Example 1 The fatty acid ester was made by reacting 130.8 parts of sunflower fatty acid and 32.7 parts of Prifac 8960, a conjugated fatty acid obtainable from Unichema, with 41.8 parts of di-trimethylolpropane. The mixture was slowly heated to 240 ° C and the water was stirred until the acid number was less than 4 milligrams of KOH per gram. The fatty acid ester was cooled to 170 ° C and 13.2 parts of the trimellitic anhydride were added. The mixture was maintained at 170 ° C for 30 minutes and then cooled to 140 ° C. 379.0 parts of dipropylene glycol dimethyl ether were added and the temperature was maintained at 140 ° C. A mixture of 47.3 parts of methacrylic acid, 181.8 parts of methyl methacrylate, 131.3 parts of butyl methacrylate, 25.4 parts of butyl acrylate and 16.7 parts of tertiary butyl perbenzoate was prepared and added to the fatty ester through 3 to 4 hours. When all of the monomer mixture had been added, the product was maintained at 140 ° C for four additional hours. Vacuum was applied and the solvent was removed until the content of the non-volatile substances was greater than 80 weight percent. The vacuum was released and the resin was diluted to 75.3 percent NVC with butyl glycol. The product was cooled and discharged. It had a color of 5 Gardner, a viscosity of 25 ° C of 143,300 mPa.s, a content of non-volatile substances of 75.3 percent and an acid number of 65.7 milligrams of KOH per gram. The product was neutralized with diisopropylamine and diluted to a non-volatile content of 30 percent with water to provide a clear solution. The appropriate desiccators (Combi LS) were added to provide a final clearcoat with a NVC of 30.2 percent, a viscosity of 300 mPa.s at 25 ° C and a pH of 10. A film of this lacquer had a - - minute sand-drying time and dried thoroughly in 1 hour to provide a coating with a Koening hardness of 14.4 percent after 1 day, 18.0 percent after 7 days and a gloss from 60 ° to 90 percent .

Example 2 The fatty acid ester was made by reacting 122.4 parts of the sunflower fatty acid and 30.6 parts of conjugated fatty acid Prifac 8960, with 39.1 parts of di-trimethylolpropane. The mixture was slowly heated to 240 ° C and the water was stirred until the acid number was less than 4 milligrams of KOH per gram. This ester of the fatty acid was cooled to 170 ° C and 12.4 parts of the trimellitic anhydride were added. The mixture was maintained at 170 ° C for 30 minutes and then cooled to 138 ° C. 354.9 parts of xylene were added and the temperature was maintained at 138 ° C. A mixture of 44.3 parts of methacrylic acid, 122.4 parts of methyl methacrylate, 123.1 parts of butyl methacrylate, 71.6 parts of butyl acrylate and 15.6 parts of tertiary butyl perbenzoate was prepared and added to the fatty ester through 3 to 4 hours. When all the monomer mixture had been added, the product was maintained at 138 ° C for four additional hours. Vacuum was then applied and the xylene was removed until the content of non-volatile substances was greater than 98 weight percent. The vacuum was released and the resin was diluted to 90 percent NVC with butyl glycol. The product was cooled and discharged. It had a Gardner color, a viscosity of 100 ° C of 3,050 mPa.s, a non-volatile content of 90.1 percent and an acid number of 59.1 milligrams of KOH per gram. The product was neutralized with ammonia and diluted with water to provide a clear solution. Suitable desiccators (Combi LS) were added to provide a final clearcoat with an NVC of 25.9 percent, a viscosity of 80 mPa.s at 25 ° C and a pH of 9.1. A film of this lacquer had a sand drying time of 24 minutes and had completely dried within 7 hours to provide a coating with a Koening hardness of 6.9 percent after 1 day, 10.6 percent after 7 days and a luster of 60 ° of 89 percent.

Example 3 The fatty acid ester was made by reacting 135.5 parts of fatty acid of Resin Oil and 33.9 parts of the conjugated fatty acid Prifac 8960, with 23.6 parts of pentaerythritol. The mixture was slowly heated to 240 ° C and the water was stirred until the acid number was less than 4 milligrams of KOH per gram. This ester of the fatty acid was cooled to 170 ° C and 12.4 parts of trimellitic anhydride were added. The mixture was maintained at 170 ° C and 12.4 parts of trimellitic anhydride were added. The mixture was maintained at 170 ° C for 30 minutes and then cooled to 138 ° C. 354.4 parts of xylene were added and the temperature was maintained at 138 ° C. A mixture of 44.2 parts of methacrylic acid, 122.3 parts of methyl methacrylate, 123.0 parts of butyl methacrylate, 71.6 parts of butyl acrylate and 15.6 parts of tertiary butyl perbenzoate was prepared and added to the fatty ester through 3 to 4 hours. When all the monomeric mixture had been added, the product was maintained at 138 ° C for four additional hours. Vacuum was applied and the xylene was removed until the content of non-volatile substances was greater than 98 percent. The vacuum was released and the resin was diluted to 90 percent NVC with butyl glycol. The product was cooled and discharged. It had a Gardner color 6, a non-volatile content of 89.8 percent and an acid number of 61.0 milligrams of KOH per gram. The resin was converted to a coating using the following formulation: Resin with solids content of 89.8 percent 55.5 Water 40.0 Ammonia solution (35%) 4.5 Bayo ett 448 0.25 Combi LS (desiccant) 1.0 Methylethyl ketoxime 0.25 Water 90 The resin was heated to 50 ° C and the water / ammonia premix also at 50 ° C, was added until the resin was neutralized to a pH of 8.5 to 9.0, at which time the solution became clear. The remaining components were added under conditions of slow agitation, with the final amount of water added to provide a shear viscosity of 200 mPa.s to 10,000 sec -1 A molded film of this solution had a sand drying time of 50 minutes , a hard drying time of 4 hours. There was no evidence of tack after 24 hours of drying and the film had excellent luster and water resistance.

Example 4 The fatty acid ester was made by reacting 113.9 parts of sunflower fatty acid and 28.5 parts of Prifac 8960 conjugated fatty acid, with 36.3 parts of di-trimethylol propane. The mixture was slowly heated to 240 ° C and the water was stirred until the acid number was less than 4 milligrams of KOH per gram. This ester of the fatty acid was cooled to 170 ° C and 11.5 parts of trimellitic anhydride were added. The mixture was maintained at 170 ° C for 30 minutes and then cooled to 138 ° C. 330.0 parts of xylene were added and the temperature was maintained at 138 ° C. A mixture of 25.8 parts of methacrylic acid, 113.8 parts of methyl methacrylate, 114.4 parts of butyl methacrylate, 66.6 parts of butyl acrylate, 15.3 parts of hydroxyethyl methacrylate and 14.5 parts of tertiary butyl perbenzoate was prepared and added to the fatty ester through 3 to 4 hours. When all the monomeric mixture had been added, the product was maintained at 138 ° C for four additional hours. Vacuum was applied and the xylene was removed until the content of non-volatile substances was greater than 98 percent. The vacuum was released and the resin was diluted to 80 percent NVC with bicalglycol. The product was cooled and discharged. It had a 3 Gardner color, a non-volatile content of 79.8 percent and an acid number of 45.5 milligrams of KOH per gram. The resin was converted to a coating using the following formulation: Resin at a solids content of 79.8 percent 62.5 Water 40.0 Ammonia solution (35%) 4.1 Bayo ett 448 0.25 Combi LS (desiccant) 1.0 Methylethyl ketoxime 0.25 Water 90 La resin was heated to 50 ° C and the water / ammonia premixed also at 50 ° C, was added until the resin was neutralized to a pH of 8.5 to 9.0, at which time the solution became clear. The remaining components were added under conditions of slow stirring, with the final amount of water being added to provide a high shear viscosity of 200 mPa.s to 10,000 sec-1. A molded film of this solution had a sand drying time of 1 hour and 10 minutes, a hard drying time of 4 hours and 15 minutes. There was no evidence of tack after 24 hours of drying and the film had excellent luster and water resistance. The aforementioned procedure was repeated, but the ammonia solution was replaced with 3.2 grams of di-isopropylamine. A clear varnish was obtained, but during the application the sand drying and hard drying times were extended up to 5 hours and 12 hours respectively. The molded film still showed some tack after drying overnight and had a lower water resistance.

Example 5 85.1 parts of the resin solution of Example 4 (80 percent in butyl glycol) was heated at 50 ° C. 2021 parts of morpholine were added and the mixture was stirred for 10 minutes, after which time 0.59 part of ethylene diamine was added. After an additional stirring period of 10 minutes at 50 ° C. 7.50 parts of Tolonate HDT were added. The mixture was maintained at 50 ° C for 30 minutes to allow the reaction of the amine, then 4,789 parts of morpholine were stirred for 10 minutes. Finally water was slowly added at 50 ° C with stirring to provide a thixotropic binder dispersible in water with a solids content of 40 percent and a pH of -9. In addition to the evident presence of thixotropy as can be observed visually, the thixotropy was also verified by determining a curve of recovery of oscillation of shear pre-effort in which it was observed that the elastic component G 'after a period of 800 seconds dominates the component G '' viscous.

Example 6 80 parts of the binder of Example 4 diluted in 80 percent NVC in dipropylene glycol dimethyl ether was heated at 50 ° C. 1 part xylene diamine was added and the mixture was stirred for 10 minutes, after which 6.3 parts of a tridecanol / TDI adduct was added and the mixture was stirred for an additional 10 minutes. 4.4 parts of morpholine were added and the mixture was stirred. Finally, 140 parts of water were added at 50 ° C slowly with stirring to provide a thixotropic binder reducible in water with a solids content of 31.4 percent.

Claims (16)

CLAIMS:

1. A binder for a water-based coating composition, the binder being obtainable as a product of a reaction mixture comprising: (a) a carboxyl-terminated fatty acid ester obtainable as a reaction product of a self-fatty acid oxidizable and a polyol, followed by a reaction to fix a carboxyl group, (b) an ethylenically unsaturated carboxylic acid; Y (c) an ester of an ethylenically unsaturated carboxylic acid.

2. A binder according to claim 1, wherein an ethylenically unsaturated monomer is also included in the reaction mixture.

3. A binder according to claim 1 or claim 2, wherein a functional hydroxyl monomer material is also included in the reaction mixture.

4. A thixotropic binder obtainable as the reaction product of a binder according to claim 3, with at least one amine, followed by reaction with an isocyanate material.

5. A binder according to any of claims 1 to 4, wherein the reaction mixture is reacted in the presence of an organic solvent.

6. A binder according to any of claims 1 to 5, wherein the fatty acid ester has a hydroxyl number of 10 to 100 milligrams of KOH per gram, preferably 20 to 70 milligrams of KOH per gram.

7. A binder according to any of claims 1 to 6, wherein an equivalent polymer formed solely from the polymerization of reactants (b) and (c), and also the monomer of claim 2, if present, has a glass transition temperature from 263 ° K to 373 ° K, preferably from 273 ° K to 343 ° K.

8. A binder according to any of claims 1 to 7, having an acid number of 20 to 75 milligrams of KOH per gram, preferably 35 to 70 milligrams of KOH per gram.

9. A binder according to any of claims 1 to 8, wherein the reaction mixture further comprises from 20 percent to 50 percent by weight of an organic solvent based on the weight of the reaction mixture.

10. A binder according to any of claims 1 to 9, wherein the organic solvent is removed essentially after completion of the reaction.

11. A binder according to any of claims 1 to 10, wherein the fatty acid ester is capable of being obtained as the reaction product of a self-oxidising fatty acid and a polyol, followed by a reaction to fix a group of carboxy terminal.

12. A binder according to any of claims 1 to 10, wherein the fatty acid and the polyol are reacted to an acid number of 0 to 10 milligrams of KOH per gram, preferably to less than 5 milligrams of KOH. per gram.

13. A binder according to claim 11 or claim 12, wherein the fatty acid is a non-conjugated acid or a conjugated acid, or a mixture of conjugated and unconjugated acids.

14. A binder according to any of claims 1 to 13, wherein the carboxylated fatty acid ester contributes from 20 percent to 80 weight percent by weight of the binder. fif. A binder obtainable by neutralizing a binder according to any one of claims 1 to 14. 16. A coating composition comprising a binder in accordance with claim 15 and water.