MXPA96001617A - Aqueous emulsions of alkydal resin, externally emulsified, obtained from renovab starting materials - Google Patents

Abstract

An aqueous emulsion of alkyd resin is disclosed comprising: a) an alkyd resin prepared from (a1) a fatty acid or an oil, (a2) at least one relatively high functionality compound whose functional groups are selected from hydroxyl groups and carboxyl, and b) an emulsifier, in which all the starting materials required for components a) and b) can be prepared exclusively from renewable substances.

Description

ACOUS EMULSIONS OF ALKYDAL RESIN. EXTERNALLY EMULSIFIED. OBTAINED FROM RENEWABLE STARTING MATERIALS DESCRIPTION OF THE INVENTION The present invention relates to a process for the preparation of aqueous dispersions of alkyd resin from exclusively renewable raw materials. The binders of coatings dilutable with water have increased their importance constantly in recent years. This trend will become substantially stronger in the future. Two main factors are critical for this development: on the one hand, the environmental problems associated with the use of solvent, and on the other hand the reduction of starting materials, which can lead to difficulties in the supply. The binders that are produced exclusively from renewable starting materials and that are also free of conventional solvents are an ideal response to these aspects, since not only can they be prepared in a partially compatible form with the environment but they are also biodegradable and are not biodegradable. they depend on oil as their primary raw material. Among the conceivable classes of binders, the alkyd resins seem to be the best to satisfy the conditions mentioned above, since the alkyd resins that are common today, on the one hand consist of up to 60% of renewable starting materials, the synthesis taking place without the use or emission of harmful byproducts, and on the other hand they can be transferred to the aqueous phase with relative simplicity with the help of suitable emulsifiers. Alkyddial resins are predominantly hydrophobic substances that do not form per se stable dispersions in water. Therefore, it is necessary to add emulsifiers. Emulsifiers are, in general, substances that have an amphipathic molecular structure, that is, their molecule consists of a hydrophobic portion and a hydrophilic portion. As a result of this structure, the emulsifying molecules accumulate on the adjoining water / resin surface, reduce the tension of the adjoining surface, and in this way are able to form very fine resin droplets in the aqueous phase. Numerous alkyd resin solutions are already known, and differ essentially in the emulsifiers used. Said systems are described in the patents of E.U.A. US Pat. Nos. 3 223 656, 3 269 967 and 3 440 193 and in the GDR patent DD 66 633, and German patents DE-C 27 54 141, 27 54 092, 2i +? +0 946 and 27 54 091. Such emulsifiers , added in quantities of 5 to 15%, based on the mass of the resin give rise to suspensions of accommodating stability. DE-A-34 04 556 describes emulsifiers based on alkyl glycosides, which can be used in alkyd resin emulsions and consist predominantly of renewable starting materials. All systems known from these documents have a common aspect in that, although binders and emulsifiers can be prepared to a high degree from renewable starting materials, the synthesis necessarily involves the use of starting materials based on of petrochemicals. The object of the present invention, therefore, is to develop an aqueous emulsion of alkyd resin wherein both the alkyd resin and the emulsifying resin are composed exclusively of renewable starting materials. This object has been achieved with the provision of the alkyd and emulsifiable resins according to the invention and their use according to the invention. Therefore, the invention provides an aqueous emulsion of alkyd resin comprising: a) an alkyd resin prepared from (a) a fatty acid or an oil, (a2) at least one compound of relatively high functionality whose groups functional groups are selected from hydroxyl and carboyl groups, and b) an emulsifier, wherein all the starting materials required for components a) and b) can be prepared exclusively from renewable starting materials. The invention further provides a process for the preparation of coating compositions consisting of an aqueous emulsion of alkyd resin and, if desired, of auxiliaries and additives which are known in the coating art. Finally, the invention also provides for the use of the binder combinations according to the invention, paint binders, coating compositions and drying compounds. The alkyd resins (a) suitable according to the invention are polyesters modified with fatty acids. The alkyd resins are prepared from saturated and / or unsaturated fatty acids or oils, polyalcohols, polycarboxylic acids or hydroxycarboxylic acids. Fatty acids can be replaced, at least in part, by other oncocarbon acids. Fatty acids are generally understood to be linear or branched aliphatic monocarboxylic acids having from 6 to 35 carbon atoms. The fatty acids can be non-drying or drying. Examples of suitable non-drying fatty acids are linear or branched, saturated or monounsaturated aliphatic monocarboxylic acids, in each case individually or as a mixture, preferably having from 6 to 16 carbon atoms. Examples of suitable drying fatty acids are unsaturated fatty acids or fatty acid mixture containing at least one linear or branched, unsaturated aliphatic monocarboxylic acid having at least 2 isolated or conjugated double bonds and a greater number of iodine than 125 g / (100 g). Preference is given to linear unsaturated fatty acids having from 16 to 16 carbon atoms. Specific examples of suitable non-drying fatty acids are 2-ethoxyanoic acid, isononanoic acid, Versatic acid or coconut fatty acid, and also oleic acid. Preferred examples of drying fatty acids are unsaturated monocarboxylic acids having an iodine number greater than 125 g / (100 g) and 16 carbon atoms. These include, in particular, unsaturated fatty acids having 2 or 3 isolated double bonds and various steric configurations, and the corresponding "acids with conjugated double bonds", that is, unsaturated fatty acids having conjugated double bonds. Such fatty acids are present, for example, in natural oils such as linseed oil, soybean oil, safflower oil, cottonseed oil, castor oil, sunflower oil, ground walnut oil, wood oil and oil. of dehydrated resin. The unsaturated fatty acids obtained therefrom are, for example, fatty acid of linseed oil, fatty acid of safflower oil, fatty acid of tallow oil, fatty acid of cottonseed, fatty acid of ground walnut oil, fatty acid of wood oil, ricinic acid or fatty acid of sunflower oil. In order to incorporate the fatty acids into the alkyd resins, it is possible either to esterify the fatty acids with the alcohol components or to introduce them into the alkyd resin by transesteri fi cation reactions of the oils. It is also possible to use the so-called technical grade fatty oils such as fatty acids, these oils are generally mixtures of cis-1-inoléic acid, linoleic acid, oleic acid and stearic acid. The oils or fatty acids of technical grade can be used as such or be incorporated into the alkyd resin by transesterification reactions or after dehydration reactions (ricinic fatty acids). When using polyunsaturated fatty acids, it is particularly preferred to use mixtures of fatty acids containing isolated and conjugated unsaturation, for example mixtures containing from 10 to 60% by mass of fatty acids containing conjugated unsaturation. The content by mass of saturated and unsaturated fatty acids incorporated is preferably from 20 to 60%, based on the resin solids. This saturated and unsaturated fatty acid component comprises, in particular, 10 to 60% of unsaturated fatty acids having conjugated double bonds. For non-yellow resins, preference is given to unsaturated monocarboxylic acids or fatty acids having one or two isolated double bonds. The fatty acids obtained can be chemically improved by fractional distillation, isation or conjugation. In order to modify the properties of the alkyd resins, it is possible to replace up to 15% by mass of the unsaturated fatty acids with other monocarboxylic acids, such as benzoic acid, benzoylglycine (hippuric acid), andlic acid, cinnamic acid or abietic acid. Naturally functional compounds (a2) of relatively high functionality contain in each case at least two functional groups selected from hydroxyl and carboyl groups. This class includes dicarboxylic acids, polycarboxylic acids, polyhydroxypolycarboxylic acids and polyols having at least 2 or up to 6 hydroxyl groups. The aliphatic or aromatic polyhydroxypolycarboxylic acids contain at least one carboxyl group and at least 2, preferably 2 or 3 hydroxyl groups, or at least two carboxyl groups and at least one, preferably one to three hydroxyl groups. It is also possible to use some or all of the carboxylic acids in the form of their anhydrides. The individual compounds of the component (a2) and their amounts are chosen so that their average functionality in the mixture is greater than 2. As dicarboxylic acids of renewable starting materials, it is possible to use saturated dicarboxylic acids, for example acid oxalic, alonic acid, suction acid, glutaric acid and adipic acid, as well as unsaturated carboxylic acids, for example fumaric acid. The aforementioned hydroxycarboxylic acids are glycolic acid, lactic acid, rieinoleic acid, gluconic acid and glucuronic acid, salicylic acid and gharic acid, hydroxy polycarboxylic acids are also particularly suitable, for example malic acid, citric acid, tartaric acid, sugar acid and mucic acid. Examples of polyols that can be used are glycerol and carbohydrates or their derivatives, such as adonitol, arabitol, sorbitol, mannitol, glucose and frucose. As emulsifiers, it is possible to use acid derivatives, carbohydrate derivatives (sugars) and polypeptides, and their derivatives. Examples of suitable emulsifiers are alkali metal salts or fatty acid amine salts, alkylglycosides, for example as described in DE-A 34 04 556, alkylpolysaccharides, sorbitol mono- and diesters, ethoxylated sorbitol esters, sorbitol hexaesters, fatty acid gluconamides, fatty acid taurides, glycolipids, lipopeptides, phospholipids and polymeric surfactant bioagents, for example lecithin, casein, or "-Emulsan", a protein complex and a lipolyheterosaccharide. It is also possible to use mixtures of these surfactants. The alkyd resins can be prepared by polycondensation according to known methods, as described, for example, in S. Paul, Surface Coatings, p. 70 to 139, John Wiley &; Sons, New York 1965.

The polycondensation can be carried out by heating in the melting bath, or by an azeotropic method with removal of water. The desired number of hydroxyl and acid groups can be introduced by appropriate choice of equivalents ratios, an appropriate reaction rate, and if desired, working in steps. The conditions of procedure and the appropriate selection criteria are familiar to those skilled in the art. The alkyd resins according to the invention preferably have hydroxyl numbers of 1 to 60 mg / g, acid numbers of 1 to 20 mg / g or oil lengths of 10 to 60%. Particular preference is given to alkyd resins having hydroxyl numbers of 20 to 70 mg / g, acid numbers of 2 to 15 mg / g or oil lengths of 50 to 70%. In order to prepare the emulsions of alkyd resin, it is possible as a first step to mix these alkyd resins with the emulsifiers or emulsifying dispersions mentioned above. The mixture comprises from 40 to 97 parts, preferably from 50 to 95 parts by weight of the specific hydrophobic alkyd resins as a mixture with from 3 to 60 parts, preferably from 5 to 50 parts by weight of the specific emulsifiers. The mixtures can be prepared or simply by mixing the synthetic resins with the emulsifiers.

To prepare the aqueous dispersions of alkyd resins according to the invention, the mixtures of the invention are dispersed in water, which can be carried out by simply stirring water in the initially introduced mixture of the synthetic resins with the emulsifier, using solvents or usual stirrers, or pouring the mixture into the water with vigorous stirring. If desired, part of the water may first be added to the above-described mixture, and this mixture may then be poured with agitation to the residual amount of water. In this way, it is possible to obtain stable emulsions of oil in water. The alkyd resin emulsion can also be prepared by first making an aqueous solution of the emulsifier and then stirring the alkyd resin in this solution with severe shear stress. The aqueous dispersions obtained in this way are valuable aqueous binders for the coating compositions. They can be used on any desired substrate, as such or in combination with auxiliaries and additives known in coating technology, for example fillers, pigments, solvents, driers and leveling assistants, to produce coatings. Suitable pigments are the customary pigments as described, for example in DIN 55 944. Examples of those employed are carbon black, titanium dioxide, mono-dispersed silica, aluminum silicate, metallic powders or scales, organic-colored pigments. and inorganic, anti-corrosion pigments, such as lead compounds and chromate compounds, and metallic effect pigments. In addition to the pigments and fillers, it is also possible, if desired, to use custom organic dyes. It is also possible to add proportions of intertwined organic icroparticles. Methods for preparing the coating compositions of the individual components are known. For example, it is possible to disperse these pigments in a particularly suitable grinding resin and, if desired, grind the dispersion to the required particle size. An alternative process encompasses the grinding of the pigments in the aqueous dispersion of the binder component. In this context, it must be ensured that the stability of the aqueous dispersion is not affected during the grinding process. After the dispersion of the pigments, it is possible to add other binder components. These may comprise the same or other dispersions of externally emulsified alkyd resin according to the invention. If appropriate, additional coating auxiliaries may be added to influence properties such as, for example, dispersibility. According to a further process, the externally emulsified alkyd resins or, if desired, other custom paste queens are first mixed with a little water, with or without the addition of fillers, pigments, dyes and the like, and this The mixture is processed on a roller bed or in a ball mill to form a paste. This paste can then be diluted with more water, without or with the addition of resin emulsion and additional additives, to produce the ready-to-use coating formulation. The coating compositions according to the invention can be applied to the materials to be coated using customary techniques, for example dripping, spraying or rolling. The applied film is then entangled by oxidative drying. The thickness of the coatings applied depends on the intended use of the coating composition. For example, transparent coatings have a thickness of up to 60 μm, fed base coatings or top coatings of 10 to 50 μm, fillers or coatings of deodorant resistance a thickness of 30 to 100 μm, and sizing coatings against the corrosion have a thickness of 20 to 70μm. Suitable substrates are any desired substrates, for example metal substrates, in this case iron, aluminum or zinc, non-metallic substrates, such as mineral substrates (e.g., concrete, glass), wood, paper, cardboard, textiles, substrates. of plastic, such as polyolefins, polycarbonates and polyurethanes, and also substrates which, if desired, have been provided with preliminary coatings. It is applied to a substrate already coated whose coating has been dried or interlaced before the second application. The coating composition according to the invention is also suitable for use in any multiple coating system. In this context, it is possible, depending on the pigmentation, to produce a clear coating composition, basecoat or topcoat compositions and also coatings, fillers or finishes with crushing resistance, for example. The preferred use is a clear coating composition applied to a base coat based on an aqueous solvent-containing coating composition. Paricularly preferred is the use as a pigmented top coat. The coatings obtained in this way are distinguished by their high resistance to damage, their high gloss retention capacity and improved strength properties. After the evaporation of the water, the entanglement and the cure of the reversals can take place by means of atmospheric oxygen or hydroperoxides, catalyzed with metallic salts or drying acids or other drying agents, at temperatures between room temperature and 2 ° C. The following examples illustrate the invention, the parts and percentages are en masse unless otherwise specified.

EXAMPLES Alkyddial Resins i 600 g of soybean oil and 170 g of glycerol were stirred together with 0.05 g of LiOH and 0.3 g of triphenylphosphite at 250 ° C under nitrogen for 3 hours, until a 1: 1 sample with ethanol formed a transparent solution. Then, at 250 ° C with stirring, 105 g of succinic anhydride was added. After an acid number was reached below 5 mg / g, an additional 110 g of succinic anhydride was added. When an acid number was again reached below 5 mg / g, the mixture was cooled to 160 ° C and 100 g of rosin was added. After about 4 hours at 250 ° C, with an amount of distillate of about 41 g and an acid number of 3 to 5 mg / g, boiling was finished. A 100% alkyd resin with a 60% oil length and a theoretical OH number of 60 mg / g was obtained.

A2 600 g of soybean oil and 150 g of glycerol were stirred together with 0.05 g of LiOH and 0.3 g of triphenyl phosphate at 250 ° C under nitrogen for 3 hours, until a 1: 1 sample with ethanol formed a solution transparent. Then, at 250 ° C with stirring, 105 g of succinic anhydride was added. After an acid number was reached below 5 mg / g, an additional 110 g of succinic anhydride was added. The mixture was then heated slowly to 170 ° C. After about 5 hours, with a distillate amount of about 36 g and an acid number of 6 to 6 mg / g having been reached, the boiling was finished. A 100% alkyd resin with an oil length of 67% and a theoretical OH number of 42 mg / g was obtained.

A3 600 g of soybean oil, 143 g of glycerol and 150 g of an aqueous solution of sorbitol with 70% strength together with 0.05 g of LiOH and 0.3 g of trifluorophosphite at 250 ° C under nitrogen for 3 hours were stirred. hours. Then 40 g of succinic anhydride was added in portions at 270 ° C, with stirring, until the batch was a single phase. At this point, 100 g of succinic anhydride was added and stirring was continued at 270 ° C. After an acid number was reached below 5 mg / g an additional 75 g of succinic anhydride was added. After about 6 hours, with an amount of distillate of about 66 g and having reached an acid number of 6 to 10 mg / g, the boiling was finished. A 100% alkyd resin was obtained with an oil length of 63%.

A4 600 g of soybean oil and 160 g of glycerol were stirred together with 0.05 g of LiOH and 0.3 g of triphenyl phosphite at 250 ° C under nitrogen for 3 hours, until a 1: 1 sample with ethanol formed a clear solution . Then, 105 g of succinic anhydride was added with stirring at 250 ° C. After an acid number was reached below 5 mg / g, the mixture was heated to 160 ° C and then 140 g of malic acid was added. After 3 hours at 160 ° C, the mixture was slowly heated to 240 ° C. After about 5 hours, the boiling was terminated reaching an acid number of 6 to 6 mg / g. A 100% alkyd resin was obtained with an oil length of 65%. 600 g of soybean oil, 520 g of 70% pure sorbitol and 100 g of succinic anhydride were heated under nitrogen together with 0.05 g of LiOH and 0.3 g of triphenyl phosphite. the condensation was then carried out at temperatures up to 230 ° C, with distillation of 245 g of reaction water. After an acid number was reached below 5 mg / g, 150 g of succinic anhydride and 155 g of additional B0cenol HD were added (unsaturated fatty alcohol). By further condensation at an acid number of 5 mg / g at temperatures up to 220 ° C, with distillation of 27 g of additional water of reaction, a 100% alkyd resin was obtained.

Alauidálica resin emulsions The 16 g of fatty acid of soybean oil and 3 g of ammoniacal water with a resistance of 25% to 200 g of the alkyd resin of example Al were added and the mixture was stirred at 70 ° C for 60 minutes until it became homogeneous. Then, 175 g of deionized water heated to 70 ° C were slowly added dropwise with vigorous stirring (about 4 hours). An aqueous, milky dispersion with a solids content of 55% by mass was obtained.

Eg 30 g of bound C-12 glycagon and 0.5 g of onical water were added with a 25% strength to 200 g of the alkyd resin of Example A2 and the mixture was stirred at 70 ° C for 60 minutes until it was made homogeneous Then, 210 g of deionized water heated to 70 ° C were added dropwise very slowly with vigorous stirring (about 4 hours). A viscous, milky production with a solids content of 52% by mass was obtained. 13 20 g of fatty acid of soybean oil, 6 g of soy glucamide and 19 g of ammonium water with a resistance of 25% to 200 g of the alkyd resin of the example were added.

A3 and the mixture was stirred at 70 ° C for 60 minutes until it became homogeneous. Then, 257 g of deionized water heated to 70 ° C were added dropwise very slowly with vigorous stirring (about 4 hours). A viscous, milky dispersion having a solids content of 45% by mass was obtained.

E4 16 g of tauride of linase oil fatty acid and 0.5 g of ammonia water with a 25% strength to 200 g of the alkyd resin of Example A4 were added and the mixture was stirred at 70 ° C for 60 minutes until made homogeneous. Then, 200 g of deionized water heated to 70 ° C were added dropwise very slowly with vigorous stirring (approx. 4 hours). A viscous, milky dispersion having a solids content of 52% by mass was obtained.

Claims (7)

NOVELTY OF THE INVENTION CLAIMS

1. - An aqueous emulsion of alkyd resin characterized in that it comprises: a) an alkyd resin prepared from (a) a fatty acid or an oil, (a2) or at least a compound of relatively high functionality whose functional groups are selected from hydroxyl groups and carboxyl, and b) an emulsifier, wherein all the starting materials required for components a) and b) can be prepared exclusively from renewable starting materials.

2. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that saturated or unsaturated monocarboxylic acids, linear or branched, aliphatic, are used individually or as a mixture, as component (a) for prepare the alkyd resin.

3. An aqueous emulsion of alkyd resin according to claim 2, further characterized in that monocarboxylic acids having 6 to 16 carbon atoms are used.

4. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that linear or branched polyunsaturated aliphatic monocarboxylic acids are used, having at least two isolated or conjugated double bonds, in each case individually or in mixture, as the component (al) to prepare the alkyd resin.

5. An aqueous emulsion of alkyd resin according to claim 4, further characterized in that polyunsaturated fatty acids having 16 to 16 carbon atoms as the component (al) to prepare the alkyd resin.

6. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that mixtures of fatty acid are used in the form of natural oils as the component (ai) to prepare the alkyd resin.

7. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that the compounds according to (a2) are selected from the group consisting of polyfunctional hydroxyaliphatic compounds having at least 2 or up to 6 hydroxyl groups, acids dicarboxy saturated and unsaturated and aromatic aliphatic, and hydrocarboxylic acids having at least one hydroxyl group and one carboxyl group, the average functionality of component (a2) being greater than 2. 6.- An aqueous emulsion of alkyd resin according to claim 7, further characterized in that the component (a2) comprises aliphatic or aromatic hydroxycarboxylic acids containing either a carboxylic group and at least 2 hydroxyl groups or 2 or more carboxyl groups and by at least one hydroxyl group. 9. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that the emulsifiers are selected from the group consisting of fatty acid derivatives, carbohydrate derivatives and polypeptides. 10. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that the alkyd resin has an OH number of 1 to 60 mg / g. 11. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that the alkyd resin has an OH number of 1 to 20 mg / g. 12. An aqueous emulsion of alkyd resin according to claim 1, further characterized in that the alkyd resin has an oil length of 40 to 60%. 13. A coating composition comprising an aqueous emulsion of alkyd resin according to claim 1. 14. The use of a coating composition according to claim 13, to produce a single coating or higher coatings. 15. The use of a coating composition according to claim 3, to produce sizing. ACOUS EMULSIONS OF ALKYDAL RESIN. EXTERNALLY EMULSIFIED. OBTAINED FROM RENEWABLE STARTING MATERIALS SUMMARY OF THE INVENTION An aqueous emulsion of alkyd resin is disclosed comprising: a) an alkyd resin prepared from (a) a fatty acid or an oil, (a2) at least one compound of relatively high functionality whose functional groups are) selected from groups hydroxyl and carboxyl, and b) an emulsifier, wherein all the starting materials required for components a) and b) can be prepared exclusively from renewable starting substances. SD / mvs *