CH387203A - Coat composition - Google Patents

Description

The invention relates to coating compositions containing metallic pigments and to a method of incorporating aluminum pigments into coating compositions consisting of an aqueous dispersion of a film-forming agent.

In general, the incorporation of aluminum pigments into covering compositions of the type of dispersions in water gives rise to difficulties, since the so-called wetting agents which are considered necessary to allow the pigments to to disperse in the aqueous vehicle, for example in the aqueous dispersion of a film-forming agent, reduce the resistance to the action of water of the covering film finally obtained, thereby forming a layer which is unsatisfactory as regards its resistance to the action of water, to scratches, etc., and, in certain cases, as regards its appearance.

It is known that Metallic Aluminum Pigments are usually prepared in the form of a paste, that is to say a paste which consists of an intimate mixture of the powder of the Metallic Pigment itself with a hydrocarbon solvent, such as mineral spirits, heavy naphtha, turpentine, etc. According to a more common method, so-called continuous layer-forming pigments are prepared by grinding aluminum powder in the presence of a fatty acid, such as stearic acid, so that the pigment paste thus obtained also contains the fatty acid, generally or mainly in the form of a layer covering the various metal particles or flakes.

However, a serious problem arises in the incorporation of metallic pigments into compositions consisting of a dispersion in water, in particular in order to obtain an effective dispersion of the pigment, as it is supplied in paste form, in the aqueous medium. It is important, not only to introduce agents which reduce the resistance to the action of water of the finely obtained layer, but also to preserve the covering composition in its aqueous nature in principle, for which possesses the characteristics. advantageous risks of these products. That is, an important feature of such waterborne coating compositions used as paints, or in other applications, is the ability to thin them with water and clean up. brushes, rollers or other instruments used to apply them, with water or with RTI ID="0001.0269" WI="13" HE="4" LX="1270" LY="1654"> aqueous solutions simple detergents.

The object of the invention is a coating composition in the form of an aqueous dispersion, characterized in that it contains water, a film-forming agent, a metallic pigment, a hydrocarbon solvent, a surfactant active ingredient soluble in the hydrocarbon solvent whose solubility in water does not exceed 2%, and adopts the surface tension is such that this agent presents, in solution at 0.1% in a mineral spirit, an interfacial tension not exceeding not 12 dynes per cm, a coupling agent miscible with water and the hydrocarbon solvent, and an auxiliary emulsifying agent formed by a salt of a fatty acid and ammonia, or a volatile amine compound. It has also been found that by thus forming the composition by incorporating therein the organic solvent as it exists in the aluminum phase and preferably adding it to facilitate the preparation, a mixture is obtained which consists of a oil in water emulsion. The new composition possesses satisfactory qualities of permanence and lasting resistance and comprising the metallic pigmentation which is desired.

0n therefore obtains, by the combination of the actions exerted by the surfactant substantially insoluble in water, by the coupling agent and by the auxiliary emulsifying agent mentioned above, an effective dispersion of the powder of aluminum in a coating composition. The preparation thus obtained contains water in the continuous phase, the film-forming agent and the aluminum powder in dispersion or suspension, as well as the organic solvent, contained in the form of an oil emulsion in the water, while the metal powder particles are probably retained by the dispersed particles or droplets of the oil phase.

When employing compositions of the invention consisting of an oil-in-water emulsion, an effectively bonded layer of the aluminum pigment is obtained. During drying, the emulsion breaks down, probably after Ura first turns into a water-in-oil emulsion. In all cases, the composition then has the effect of forming an adherent, extremely durable layer of metallic flakes. When the composition and the conditions of use are especially such as to allow the aluminum to form a continuous layer, this result can also be achieved satisfactorily, if desired.

As has already been said, another particularly advantageous characteristic of the compositions according to the invention consists in their resistance to the action of water, once dry, that is to say that they no longer contain any substance soluble in water or the like, capable of reducing the resistance of the film to the action of water. The surfactant is in principle insoluble in water and, however, in combination with the other substances mentioned above, it facilitates the formation of the desired emulsion of the oil or the hydrocarbon as well as the emulsion of the metal particles. The coupling agent is effectively volatile and therefore does not persist in the dry layer, while the auxiliary emulsifying agent, which is a soap of a volatile base, takes the form of a sensitive fatty acid. - lies insoluble. The latter agent is easily incorporated by adding ammonia, that is to say in the form of ammonium hydroxide reacting with stearic acid or other fatty acid, which may already be present, at least in part, in the dough. of metallic pigment to form a salt of fatty acid and ammonia, for example ammonium stearate, it being understood that equivalent proportions of an RTI ID="0002.0277"WI="15" HE can be added ="4" LX="531" LY="2212"> ammoniacal substance such as ammonia derivatives. The coating composition therefore contains an ammonium soap but, when it dries, once applied, the ammoniacal element is eliminated, i.e. the defined soap is defined. compound by volatilization of ammonia or equivalent element, leaving the fatty acid, essentially insoluble in water. The hydrocarbon solvent itself also volatilizes when the applied layer dries, as does the water in which the various elements are emulsified or dispersed. As a result, the layer does not tend to dissolve, soften or otherwise weaken on subsequent contact with water and forms a finishing layer resistant to the action of water. water in an efficient manner and in which the metal particles are strongly retained.

The film-forming agent can be a natural or synthetic resin or an analogous material, such as various polymeric products, natural rubber and, in fact, any substance capable of being dispersed in the form of a suspension or emulsion in the water and, when applied to the desired surface, forming a coherent film or layer over that surface by evaporation of the water. In some of these compositions, such as those containing acrylic ester resins in which the slurry film-forming agent can be considered to be, in principle, in the solid state, the dispersion can be the name of Latex, while other materials which contain a liquid agent or are carried by a liquid may be defined accordingly under the name of emulsions in water. An example of the latter type is an aqueous emulsion of an alkyd resin in an organic solvent.

Other examples of so-called Latex compositions are aqueous dispersions of styrene and butadiene resins and vinyl acetate resin, which are each polymeric substances and constitute the disperse phase of the Latex. Latexes and emulsions of these latexes and other substances are very readily available and have hitherto been used, for example with non-metallic pigments, in the preparation of paints and other finished covering substances possessing the advantageous aqueous characteristics. above. 0n can of course also incorporate other substances, pigments or dyes, when it is desired to obtain the corresponding characteristics.

The compositions can form continuous layers under a variety of application conditions, contrary to at least some previous attempts to form continuous layers with aqueous dispersion covering substances containing aluminum pigment. That is, the various flake-like metallic aluminum particles tend to rise to or near the outer surface of the film, typically settling flat in that surface and forming laying a continuous layer with it, so that the finished layer has the appearance of a metallic, shiny, substantially continuous surface.

For example, if one applies the compositions of examples 2, 3, 4, 5 and 7 given below (so-called Latex-based) On absorbent surfaces such as wood or paper, one obtains a satisfactory continuous and shiny layer. . It now appears that to form effective continuous layers on non-absorbent surfaces (such as those of various metals) it is preferable to pass most or all of the resin binder, i.e. from 1 the film-forming agent, in the oil phase of the oil-in-water emulsion, which serves to disperse the aluminum pigment instead of this agent being a component of the Latex as in the above examples. Under these conditions, as well as preferably with a somewhat higher proportion of the aluminum pigment, satisfactory continuous layers were obtained, applied to metal or other non-absorbent surfaces.

A process for incorporating metallic pigment into aqueous dispersion coating compositions can advantageously be carried out in several steps, starting, for example, with a paste of aluminum pigment containing 65-80 μm. % Al flake powder and 20-35 0/0 mineral spirits. This paste may consist of aluminum particles coated with a layer of stearic acid and mixed with mineral spirits. The process may consist first in preparing a modified paste, that is to say in modifying the paste by mixing it with the suitable surfactant and even better with an additional hydro-solvent. carbon. The surfactant should be oil soluble and substantially water insoluble, i.e. its solubility in water should not exceed about 2%, but it should possess certain characteristics of compatibility with water, in particular such that a dilute solution in mineral spirits or the like has a low surface tension with respect to water. The hydrocarbon solvent serves to expand or reduce the pigment paste or, more generally, to dilute it so as to increase its fluidity and allow it to combine more easily with the composition in aqueous dispersion and to more effectively forming an emulsion to suspend the metal particles therein or with the dispersed oil droplets (hydrocarbon solvent). The pigment paste may already contain the hydrocarbon solvent; it is then generally designated under the name of reduced dough.

Another element is the coupling agent, for example a compound of the category of alcohols and the like, which mixes with water and oil. These coupling agents are used in the preparation of emulsions and are characterized by their mutual solubility in the water and oil phases of the emulsions. If desired, RTIID="0003.0280" WI="10" HE="4" LX="597" LY="2110"> the coupling agent can be incorporated into the so-called reduced paste, thus forming a preparation more complete. The coupling agent must be relatively volatile, as will be seen below.

You can then proceed as follows: mix the paste with the resin or other layer-forming agent in aqueous dispersion. If the coupling agent has not already been incorporated, it can be added at this time. The film-forming agent is generally supplied in latex or emulsion form and can be mixed with the dough, preferably after adding some additional water, together with the coupling agent. The ammoniacal substance can also be incorporated, preferably by adding it to the aqueous vehicle, for example in the aforementioned case to the latex or to the emulsion of the film-forming agent, before combining this vehicle with the reduced paste. The final mixture containing the resin latex or the like is thoroughly agitated or otherwise mechanically treated to achieve a uniform combination and to effectively emulsify the oil therein.

It has been found that the relatively insoluble surfactant, the coupling agent and the volatile base soap which results from the combination of the ammoniacal compound with the fatty acid, cooperate remarkably in the formation an emulsion of the type of oil in water, in which the aluminum pigment is uniformly dispersed and which has the further advantage of forming an extremely satisfactory dispersion of the aluminum pigment in paints or elements analogues of this type, while preserving the aqueous character of the composition and obtaining, however, a product which, once applied, has satisfactory properties of resistance to the action of water and physical characteristics. - satisfactory siques such as a high resistance to scratches or other consequences of the effective presence of metal particles. The combined functions performed by these various substances clearly emerge from the tests carried out, particularly as regards their co-operation in the formation of the desired oil-in-water emulsion.

As already stated, the surfactant must be soluble in hydrocarbon solvents. Its maximum solubility in water is > about 2% and generally does not exceed about 1%; the surface tension is such that this agent exhibits, in a 0.1% solution in mineral spirits, an interfacial tension not exceeding 12 dynes/cm with respect to water. Preferably, the water solubility of the agent is very low, for example about 0.010/0.

As surface-active agents, heterocyclic nitrogen compounds are preferably used, whose ring comprises an alkyl or alkenyl substituent containing 12 to 22 carbon atoms, as well as a substituent containing at least one polar group, whereas the other substitution positions are occupied by low molecular weight alkyl groups containing 1 to 5 carbon atoms. Examples of a suitable polar group are the amino group or a hydroxyalkyl group containing 1 to 5 carbon atoms. The long chain group gives the compound the desired oil solubility and the polar group the water compatibility, as represented by the low interfacial tension of the oil solution with the water, while the solubility in water is substantially zero.

Compounds of the above categories can be prepared by previously described methods. For example, suitable agents of the oxazoline class can be prepared by reacting an appropriate amino-hydroxy compound with an appropriate fatty acid, in substantially equimolar proportions, more especially by reacting a beta-amine alcohol. with a fatty acid.

These materials have been found to be extremely effective and economical in the applications in question, by causing the aluminum pigment to disperse in water-based coating compositions.

An exemplary surfactant which can be used is given.

This is Alkaterge C; this compound consists of 2-oleyl-4-methyl-4 hydroxym6thyl-5-ethyl-2-oxazoline. Ort has found by testing that the interfacial tension of a 0.1% solution in mineral spirits is 8.5 dynes relative to water. The formula of this compound is as follows:

As already stated, it is important that the final coating composition mixture contain ammonia or a volatile amine base whose function is to form a volatile base soap with the fatty acid(s). contained in the malallic pulp, for example from the milling operation. The fatty acids serve as lubricants in these operations and, as is known, some of them, for example when they coat the metallic particles during grinding, cooperate in causing them to acquire dune-forming characteristics. continuous layer. If the metallic powder or paste does not contain a fatty acid, it is necessary to add some to prepare the compositions of the invention, preferably by adding this fatty acid to the metallic powder or paste before finally mixing it. with the preparation of covering resin or the like in aqueous dispersion. In fact, it appears to be advantageous, at least in certain cases, to add a fatty acid supplement to the metallic paste which already contains a certain proportion. The fatty acids which can be used to form soap ä. The volatile base which contributes to form the emulsion or dispersion of the invention are, for example, alkyl and alkenyl fatty acids, which contain 14 to 22 carbon atoms in the alkyl or alkenyl chain. Examples of these acids are stearic acid, currently the most commonly adopted in the preparation of aluminum pastes, as well as acids such as oleic, lauric, myristic, behenic, palmitic and ricinoleic acids. "0004.0278" WI="7" HE="4" LX="286" LY="2503"> that. The total amount of fatty acid in the composition may preferably range from about 1% to about 10% by weight, based on the weight of aluminum metal contained in the selected aluminum pigment. As a volatile amine compound, a substance which is particularly suitable, in view of the price and the absence of harmful odor or toxicity, is morpholine. In general, the nature and the proportion of the volatile base should be chosen so that the pH of the finished composition is at least equal to about 9, because it seems that a pH of this value or of a higher value is generally necessary to allow soap to form. As already mentioned, the addition of ammonia has the effect of facilitating the formation of an emulsion (probably by forming the aforesaid soap or water-soluble salt). Once the coating is applied and while it dries, the ammonia or morpholine evaporates and the fatty acid thus returns to its original relatively insoluble form.

The coupling agent consists, as already said, of a substance soluble in water and in oil. It consists, preferably, of an organic liquid of the category of alcohols, glycols, glycol-ethers and glycol-diethers and, in particular, of a distilling agent at a temperature below 2000 C under a pressure of 760 mm Hg , the vapor pressure of which is equal to or greater than <B>0.01</B> mm at 20° C. and which mixes in all proportions with water and hydrocarbon solvents. An example of a preferred coupling agent is the monobutyl ether of Ahylene glycol, called butyl cellosolve. An example of a very volatile compound is isopropyl alcohol, having a boiling point of 80.41°C and a vapor pressure of 40 mm at 20°C. A low volatility agent is hexylene glycol, which boils at 197.10 C and has a vapor pressure of 0.02 mm at 200 C. Other satisfactory agents are, for example, monoethyl and diethyl ether of diethylene glycol, diacetone alcohol and tertiary butyl alcohol, all of which are liquids and evaporate as the applied layer of the new composition dries. It appears, in general, that the proportion of coupling agents should preferably be between about 5% and about 15% based on the total water content RTI ID="0004.0553" WI="4" HE="4"LX ="1742" LY="1923"> of the final covering composition, since the stability appears to tend to decrease when the Proportion is lower than 5%, whereas a Proportion substantially higher than 15% has tendency to cause the film-forming agent to disperse, ie to destroy the structure of the latex or emulsion.

The compositions of the invention contain a hydrocarbon solvent; You can add this hydrocarbon solvent to the metal powder or paste. Ort preferably chooses as the hydrocarbon solvent a heavy, solvent, coal tar naphtha gasoline, for example Mil-N-15178 A (US military specification). Other hydrocarbon solvents are, for example, mineral spirits (also known as petroleum spirit), turpentine, toluene (for example industrial grade used in paints and varnishes), xylene (from the industrial quakte called solvent naphtha gasoline, used in paints and varnishes), aliphatic and aromatic naphtha gasolines of petroleum and other kinds of xylenes. In some instances, the hydrocarbon solvent may contain dissolved therein a resinous material, for example an auxiliary plasticizer or binder. In all cases, the solvent serves as a thinning or diluting agent making the metal clay more fluid and obviously providing the oil phase of the desired oil-in-water emulsion.

The proportion of coupling agent which is suitable is, for example, about 5 parts of this agent to 1 part by weight of the water-insoluble surfactant, while the total proportion of the solvent The suitable hydrocarbon (including that contained in the initial aluminum paste) is about 2 parts by weight to 1 part by weight of metallic aluminum in the paste. These proportions may vary according to requirements. Example <I>1</I> Preparation of the composition of the Aluminum Pigment A paste of Aluminum Pigment forming a continuous layer is chosen, prepared in the manner described above by grinding with stearic acid and type manufactured by the Aluminum Company of Canada Limited, under the trade name Alpaste 300-N. It contains 68% aluminum, 2% stearic acid and 30% mineral spirits. 0n intimately mix 100 parts of this aluminum paste with 10 parts by weight of Alkaterge T. The modified paste thus obtained is suitable for the preparation of the coating compositions according to the invention and is referred to in some of the examples which follow as unreduced paste. It should be understood that the aforesaid substituted oxazoline can be replaced by other surfactants possessing the characteristics described above to prepare the unreduced dough.

Mix 110 Parts of the unreduced paste prepared with 25 Parts of an alicylic ketone resin dissolved in 75 Parts of coal tar solvent naphtha gasoline, a resin suitable for this purpose consisting of the product designated by MS 2 resin, identified below. The addition of this resin, which thus constitutes an additional binder to the hydrocarbon solvent, is optional, but if added, it can consist of various substances such as alkyd resins containing styrene. The composition thus prepared can be referred to as a reduced paste.

Puls an prepares a latex vehicle as follows: an adds to 5 parts of a 15<B>%</B> solution of sodium polyacrylate of this substance in water, for example the solution prepared by the Borden Company and designated as Polyco 296-DT, approximately 2 parts of a 28 Klo solution of ammonium hydroxide in a sufficient proportion to keep the composition alkaline, i.e. its pH is at least equal to 9, thereby forming ammonium stearate with the stearic acid of the aluminum paste. 200 parts of water and 50 parts of ethylene glycol monobutyl ether are added as coupling agent. Finally, add and combine 160 Parts of Polyvinyl Mate Latex known as Polyco 678, prepared by the Borden Company.

Puls an prepares a final paint by adding the Latex vehicle to the reduced paste with agitation. The Latex-based aluminum paint thus obtained applied to absorbent surfaces (such as wooden panels, and also used in the tests of Examples 3 to 5 and 7) is glossy, waterproof and resists scratches.

Sodium polyacrylate is an optional element which serves to increase the viscosity of the latex vehicle. Among other thickening agents which may be chosen, mention may be made of methyl cellulose and ammoniacal casein.

Example <I>2</I> Ort combines 33 Parts of unreduced paste, replacing Alkaterge T by Alkaterge C in the same proportions with 6 Parts of isopropyl alcohol as coupling agent. Twenty parts of water and about one part of 28% ammonium hydroxide are added to the resulting mixture. Puls an combines the whole with 120 Parts of Acrylic Acid Latex, i.e. Emulsion Polymer of an Acrylic Acid Ester, such as in particular Acrylic Acid Ester Resin Latex. acrylic known as Rhoplex AC-33 prepared by the Rohm & Hass Company.

Note that in this example no additional hydrocarbon solvent was added and that the solvent for the initial aluminum paste is the solvent.

Example <I>3</I> A reduced pulp is prepared by adding 70 parts of coal tar solvent naphtha gasoline to 110 parts of the unreduced pulp.

Pulse prepares a Latex vehicle as follows: Mixes 5 Parts of the aforementioned Polyco 296-BT sodium polyacrylate solution with approximately 1 Part of a 28% solution of ammonium hydroxide to maintain the degree of To the desired alkalinity, pulse an adds the mixture to 200 parts of water containing 50 parts of isopropyl alcohol as a coupling agent. Puls an combines the whole with 120 Parts of the LatexRTI ID="0005.0542" WI="10" HE="4" LX="1651" LY="2363"> of Rhoplex AC-33 acrylic acid ester above , puls an prepares a paint by adding the Latex vehicle with agitation to the reduced paste.

Example <I>4</I> A reduced pulp is prepared by combining 100 Parts of the unreduced pulp with 120 Parts of coal tar solvent naphtha oil and 40 Parts of a Coumarone indene resin (as product called Cumar VS prepared by the Barrette Company of Montreal), the latter resin fulfilling the same function as the alicyclic ketone resin of Example 2 and thus constituting an optional substance which serves as an additional plasticizer and auxiliary binder.

Then prepare a latex vehicle by first adding 5 parts of Polyco 296-DT polyacrylate solution to 300 parts of water with 2 parts of 28% ammonium hydroxide. Then, 50 parts of ethylene glycol monobutyl ether are added as a coupling agent and combined with 160 parts of Rhoplex AC-33 Acrylic Acid Ester Latex. Then prepare a final paint by adding the Latex vehicle with agitation to the reduced paste. More specifically, as in the other examples above, the Latex vehicle is preferably added to the paste in small portions, stirring thoroughly after each addition. Then the test panels are painted with the final compositions of Examples 2. at 5 and an observes that the layers thus obtained do not comprise continuous layers of aluminum flakes, are shiny and perfectly resistant to the action of water and to scratches. An aluminum paste pigment is first prepared by grinding aluminum powder without fatty acid, i.e. in the absence of stearic acid or other grinding lubricant or forming agent ( A continuous layer yields a paste product containing no fatty acid and consisting of 71.3% aluminum flakes and 28.7% mineral spirits.

This special paste is first made into a reduced paste by mixing 100 parts of the paste with 10 parts of Alkaterge T, 3.2 parts of stearic acid and 80 parts of coal tar solvent naphtha.

Next, prepare a latex vehicle consisting of 4 parts Polyco 296 BT polyacrylate, 3 parts (28% aqueous ammonium hydroxide solution, 320 parts water, 40 parts hexylene glycol ( as coupling agent) and 128 Parts of Rhoplex AC-33 Acrylic Acid Ester Resin Latex. like that of the other examples, in a satisfactory emulsion of oil (without water). It is apparent from this example that the results are as good when the fatty acid is added separately, from the start during the grinding of the RTI ID="0006.0271" WI="11" HE="4" LX="877" LY="2468"> aluminum powder.

By way of comparison, tests were carried out with the same substances and by the same method of preparation as in Example 5, but eliminating various of these substances. , the final composition is a water-in-oil emulsion, and the oil-in-water emulsion cannot be obtained, probably due to the absence of the ammonium soap. an eliminates the stearic acid and the coupling agent, an also obtains only a water emulsion (without the oil, even if an only eliminates the coupling agent of the example 6. When the surfactant Alkaterge T is removed, no emulsion can be obtained in the final mixture, whether or not the stearic acid is added in the proportion indicated (in Example 5). <I>6</I> The paste of this example is a normal Aluminum Pigment paste, such as the product known as Alpaste 310, prepared by grinding aluminum powder in the presence of stearic acid and whose approximate composition is as follows: aluminum flakes 80 0/0, stearic acid 1.5%, and mineral spirits 28.5 0/0. Ort first prepares a preliminary paste, modified, but in principle not reduced, and consisting of a mixture of 45 Parts of Alpaste 310 , 5 Parts of Alkaterge T , 5 Parts of oil tar solvent naphtha coal and 0.25 part of stearic acid. Then prepare a so-called reduced paste by mixing 125 Parts of unreduced paste (described above) with 2 Parts of stearic acid and 100 Parts of coal tar solvent naphtha.

A latex vehicle is prepared containing 5 parts of the Polyco 296-BT polyacrylate solution, 3 parts of the 28% ammonium hydroxide solution, 400 parts of water, 50 parts of hexylene glycol and 160 Parts of Rhoplex AC-33 Acrylic Acid Ester Latex. After having combined in a suitable manner the reduced paste with the Latex vehicle (as (in the other examples), a satisfactory composition is obtained, which consists of an emulsion of oil (in water (in which the aluminum powder is perfectly dispersed.

Tests were also carried out with the same composition containing the same Alapaste 310, but removing the surfactant Alkaterge and increasing the Proportion of stearic acid at the same time, that is to say to 12 Parts of acid for 90 Parts of Alpaste 310 . Ort thus obtains no emulsion in the final mixture with the Latex vehicle. ="4" LX="1165" LY="2299"> oleic acid (for example 2 Parts of stearic acid and 10 Parts of oleic acid for 90 Parts of Alpaste 310, an obtained, by 1e final mixture with the Latex vehicle, an emulsion of water (without oil, but one does not obtain the desired emulsion of oil (without water). It is clear from these results that, if an replaces the insoluble surfactant in water with oleic acid, but does not obtain the desired results, although emulsification is stronger than if replaced with stearic acid. In two other trials (removing the surfactant), the proportion of ammonia is slightly increased, so that an ammonium soap with the highest quantity of fatty acid is surely formed, but as well as it has just been said, one does not obtain the structure of the emulsion which one desires. Example <I>7</I> The aqueous dispersion of the film-forming agent is constituted directly by the dispersion emulsion of the pigment of the oil phase, which contains this agent.

The same modified preliminary aluminum pigment paste of Example 6 is first prepared, the surfactant of which consists of Alkaterge T . The parts being by weight (as everywhere else), a reduced paste is prepared containing 300 parts of modified paste, 5 parts of oleic acid, 150 parts of MS2 resin (50% (without xylol), 150 parts of fatty varnish ( U.S. Federal Specification TT-V-119), and 120 parts coal tar solvent naphtha gasoline Resin MS2 is an alicyclic ketone resin sold by Howards & Sons (Canada) Ltd, of Cornwall, Ontario. , Canada, which should be considered the same as the AW2 resin described (in the following publication: British Intelligence Objectives Sub-Committee, Final Report No. 629, Item 22 Investigation of Synthetic Resine Used in the German Surface Coating Industry, pp. 10l-102, by S.R.W. Martin, J.D. Morgan & G. Weatherston, March-April 1946, published by B.I.O.S. 32 Bryanston Sq. London, W.1, England.

* The aqueous vehicle consists simply of 5 parts NH4OH (28% solution), 700 parts water and 75 parts ethylene glycol monobutyl ether (coupling agent) and the final composition is obtained by mixing 780 parts of the aqueous vehicle with 730 parts of the aforementioned reduced paste, intimate enough to obtain the desired emulsion. In preparing the product, the film-forming substance contained (in the solution of resin and oily varnish is in fact dissolved or contained (in the hydrocarbon solvent and, subsequently, the aqueous dispersion of this solvent). An example is the Oil-in-Water Emulsion prepared to retain the metallic pigment. As has already been said, the compositions according to the invention contain metallic pigments incorporated in numerous film-forming agents Other examples of these agents are therefore: styrene-butadiene resin, such as Dow 512-K prepared by the Dow Chemical Company, a polyvinyl latex such as Bakelite WC-30, and an emulsifiable alkyd resin, such as Synthemul 1504 prepared by Reichhold Chemicals, Inc. . The final structure of all the compositions according to the invention is that of an oil emulsion (without water. It may happen that during the addition of the aqueous vehicle, which can In some examples, with the dough reduced in small portions, a Water Emulsion (in the oil) is formed first, but it turns into an Oil Emulsion (in the water which is removed by continuing to add more oil). vehicle.

When the coating composition, in the form of a paint or the like, is applied to a support, the water evaporates or is sucked into the pores of a porous support, such as wood or paper. the water content that the emulsion-suspension concentrates to the point of breaking up, perhaps transforming first into a Water Emulsion (in the oil and it seems that at least (in some organic solvents thus become capable of acting freely upon the particles of resin, latex or other film-forming agent, apparently causing the surface layers of these particles to swell and dissolve, so that they adhere. In all cases, all of the water and organic solvents eventually evaporate and the ammonium stearate or equivalent volatile base soap forms. by the reaction of the ammoniacal substance, for example ammonium hydroxide with stedaric acid or other fatty acid, is composed by setting the ammonia free and leaving the fatty acid at 1 & at, in principle, insoluble.

The dry topcoats resist stains perfectly, much better than ordinary oil-resinous aluminum paints. They resist (under excellent conditions) the formation of pits due to the adhesion of the particles of resin or the like, which is obtained (in certain cases in the raw way, with the metallic flakes. They also resist perfectly to washing, because they contain substantially no water-soluble agents and the structure of the films is very tight, which results, for example, from the apparent solution of the particles of acrylic resin or RTI ID="0007.0545" WI="14" HE="4" LX="1631" LY="1982"> similar. soap and water after one hour of application.

Claims (11)

CLAIM I Coating composition in the form of an aqueous dispersion, characterized in that it contains water, a film-forming agent, a metallic pigment, a hydrocarbon solvent, a soluble surfactant (without the hydrocarbon solvent, the solubility (in the water does not exceed 2%, and whose surface tension is such that this agent presents, in solution at 0.1%, (in a mineral essence, an interfacial tension not exceeding 12 dynes per cm, a coupling agent miscible with water and the hydrocarbon solvent and an auxiliary emulsifying agent formed by a fatty acid and ammonia salt or a volatile amine comuose. SUBCLAIMS 1. Composition according to claim 1, characterized in that the metallic pigment is an aluminum pigment. 2. Composition according to claim 1, characterized in that the boiling point of the coupling agent is less than about 2000 C at the pressure of 760 mm Hg, and its vapor pressure is at least equal to to about 0.01 mm at 2011 C, and in that the auxiliary emulsifying agent is a salt of a saturated or unsaturated fatty acid containing 14 to 22 carbon atoms. 3. A composition according to claim 1, characterized in that the surfactant is a substantially water-insoluble oxazoline, and that the proportion of the composition is in the alkaline state. 4. Composition according to claim 1, characterized in that the surfactant is a heterocyclic compound whose nucleus contains at least one tertiary nitrogen atom and which comprises several substituents, one of which is a group alkyl or alkynyl containing 12 to 22 carbon atoms, at least one of the other substituents is a polar group and the others are alkyl groups containing 1 to 5 carbon atoms. 5. Composition according to claim 1 and sub-claims 1 and 4, characterized in that the coupling agent is a monovalent alcohol, a glycol, a glycol-6ther or a diether and in that the pH of the composition is equal to at least 9. 6. Composition according to sub-claim 5, characterized in that the surfactant adopts the Proportion is from 2% to 25%, based on the Pigment, is a heterocyclic compound having at least one atom of tertiary nitrogen, such as substituted 2-oxazoline, substituted 2-imidazoline, 5-amino-4,1,2-triazol. 7. Composition according to claim I, characterized in that the surfactant is a heterocyclic compound having at least one tertiary nitrogen atom such as 2-o16yl-4-methyl-4-hydroxymethyl- 5-ethyl-2-oxazoline, 2-oleyl-4,4-dihydroxym6thyl-2-oxazoline, 1-(2-hydroxymethyl)-2-oleyl-2-imidazoline, 3-oleyl-5-amino -4,1,3-triazol. B. Composition according to claim 1 and sub-claim 4, characterized in that the substituent in the 2-position of the ring is an aliphatic hydrocarbon residue containing 12 Å. 22 carbon atoms. 9. Composition according to claim I and sub-claim 5, RTIID="0008.0274" WI="18" HE="4" LX="1464" LY="850"> characterized in that the coupling agent is an ethylene glycol dthermonobutylene and the auxiliary emulsifying agent is ammonium stearate. CLAIM 1I Process for the preparation of the composition according to claim 1, characterized in that a mixture is prepared containing the metallic pigment, a fatty acid, a hydrocarbon solvent and the surfactant soluble in this solvent and a mixture containing water and coupling agent, one of which contains the substantially water-insoluble film-forming agent, and combines the two mixtures to form an oil-in-water emulsion. SUB-CLAIMS 10. Process according to claim 11, characterized in that the film-forming agent is contained in the first of the two mixtures. 11. Process according to claim 11, characterized in that the fihnogenic agent is contained in the second mixture.