IE45347B1 - A method of preparing a stable suspension of finely divided solid particles in the oil phase of an oil-in-water emulsion such as a pigmented satin - Google Patents

Abstract

The disclosure describes a method of preparing a stable suspension of micronized solid particles in the oil phase of an oil-in-water emulsion. The micronized solid particles are ground in an oil phase in the presence of one or more dispersion aids capable ? rendering the surface of the particles oleophilic and one or more sterically and/or electrostatically stabilizing dispersion agents to form a stabilized suspension. Then the suspension is emulsified in an aqueous medium in the presence of one or more emulsifiers of a type that does not affect the stability of the oil phase produced by the dispersion agent or agents and dispersion aid or aids. In this manner there is obtained, as far as stains are concerned, a product having good penetration ability and good protective effect.

Description

T.he present invention relates to a method of preparing a stable suspension of finely divided solid particles in a low viscosity liquid oil-in-water emulsion. This method thus provides a stable suspension of solid particles in a low-viscosity liquid which does not have a paste-like consistency. The invention will be explained in greater detail below with reference to penetrating pigmented stains for protection of wood and wood products, said stains showing no tendency or only a slight tendency towards stratification or sedimentation of the pigments or other suspended solid particles,but. may also he applied for example in the preparation of abrasives, polishing agents and cleaning agents.

When applying stain to a porous surface, such as wood surface, one of the conditions of obtaining good penetration is a j relatively lox-ί viscosity of the liquid compared to the rate of evaporation.

In practice, a short drying time is desired, and the absolute ! viscosity must consequently he low. If the stain is coloured wholly or partly by means of pigment particles, these particles will precipitate on standing according to Stokes' law, i.e, the rate of sedimentation is a function of particle size and viscosity This implies that the stain must be strongly stirred before use, and such compositions are therefore usually sold in buckets and similar containers offering good stirring possibility. If the ' stain is not sufficiently stirred, colour faults will occur with regard to the tint and colour intensity when the product is used.

It is known to obviate this problem in several ways: -24 53 4? The simplest method is το reduce the particle size to colloidal dimensions whereby sedimentation will ht insignificant even after long periods of tinu.. This method is applicable only to specifrc expensive products as the preparation of such a pigment dispersion is very costly.

Another, widely used method js flocculation of the pigment by addition of ss-e-uled anti-settling agents, like various polar substances. By this nethor., sedimentation is not eliminated, but the sediment will be of such a nature as to be particularly easily stirred up again. In extreme cases the pigment is flocculated so strong!_ that the product may even be sold in cans requiring only brief shaking before use. By saitl flocculation of the pigment, however, the treated surface gets a grainy, unattractive appearance and the actual penetration possibilities of the pigment are gr-atly reduced, A third possibility which is also used is to render the viscosity dependent on shear force and time by the addition of thixotropic agents such as polyamide derivatives and colloidal silicic acid, for types of stain based ta organic solvents. In this manner viscosity may be kept high cn standing while attaining the low value favourable to the penetration at the very moment of application and for a very short period thereafter. This method, however, is '.imited to the cases where very high shear forces arise during the apelicatior process, for example in application by brush, and provides no possibility of obtaining sufficiently deep penetration, as the lowering of viscosity is in practice of very short duration. -345347 It is the object of the present invention to provide a method that does not suffer from the above-mentioned drawbacks and where, as far as stains are concerned a product having good penetration ability and good protective effect can be obtained, said product showing no appreciable tendency towards stratification or sedimentation of the pigment even on prolonged standing. More generally, it is the object of the invention to provide stable suspensions of finely divided solid particles in the oil phase of a low viscosity oil-in-water emulsion without noticable tendency towards sedimentation. I The present invention provides a method of preparing a liquid low viscosity oil-in-water emulsion comprising from 1 to by weight; of oil wherein the oil phase contains a stable suspension of finely divided solid particles, which method comprises grinding the finely divided solid particles in the presence of one or more dispersion aids to render the surfaces of the particles oleophilic, suspending the particles in the oil before, during or after grinding, the suspension being stabilized by inclusion therein of ' one or more stabilizing agents, and emulsifying the stabilized suspension in an aqueous medium in the presence of one or more compatible emulsifiers. -445g4 γ Thus, the particles are incorporated and retained in the internal phase of a stable oil-in-water emulsion whose external continuous phcse is thus composed of a liquid of low viscosity.

It has thus surprisingly been found that partly by imparting 5 suitable oleophilic surface properties to the particles and partly by providing suitable steric and/or electrostatic forces between the particles and between the particles and the boundary layer of ths water phase of the emulsion, stable suspensions may ba obtained showing no tendency or only an extremely slight tendency towards sedimentation of the particles on standing.

Methods having, on the face of it, certain points of similarity to that described, but proving on close analysis to display decisive differences and which especially do not aim at or lead to products having the long-term stability obtainable by the method according to the invention are described in a number cf publications: German Offenleguiigsachrift No. 22 lg 521 describes a method cf preparing an electrophoresis hath in emulsion form in which inter alia, a pigment suspension in a water-dissolved completely neutralized carboxylic acid is added to the hath. However, the measures stated aim at retaining the pigment in the water phase, and the method is not aimed at the preparation of products with long-term stability. 453 47 Swedish Patent Specificafcion, Nb.139,292 teaches a method of preparing r.esin emulsions applicable for example as glue or for fixation of pigments on textiles. In Example 5 copper-phthalocyanine blue is distributed in a concentrated emulsifier solution to which is further added emulsifying agent, water, and an amino resin emulsion. Said emulsion, thus containing no pigment in the internal phase of the emulsion as the amino resin emulsion is prepared and added separately, is further thickened by an oil-inwater emulsion of petrol in an emulsifier solution of the kind mentioned above. Neither in this case must the pigment be expected in any way to become incorporated in the emulsion internal phase. The features characteristic of the invention ‘ are thus not at all present here.

Swedish Patent Specification No.135,667 teaches a method of preparing an emulsion concentrate which must be thinned immediately before use, and the long-term stability is consequently unimportant.

More exactly, the object is to prepare emulsions where water-insoluble protectants are dissolved in the internal phase by a method which endeavours to eliminate their possible negative impact on the emulsion stability on account of interaction with the ex+emal phase by means of a delicate stepwise correction for these interactions.

The possibility of dispersed active substances is nowhere described more specifically, and there is no mention of the conditions of possibly stabilizing a substance in the internal phase against sedimentation. Hence, there are no points of similarity to the characteristic features of the invention. -64S347 German Offenlegungsschrift No 22 56 757 discloses an emulsion which is particularly applicable as a spray and which may he of the water-in-cdl type as well as the oil-in-water type, particles of a substance with antibacterial, insecticide, herbicide or vegetation-modifying activity being dispersed in one phase.

These liquids The specific, feature ex the spray is partly the adjustment of the density ratio and volume ratio between the phases within precisely defined limits, and partly the selection of a suitable non-ionic surfactant which is hydrophobic or hydrophilic, depending on whethar the particles are desired to be present in the oil phase on in the water phase.

The possibility establishing in this way, for particles of substances of the type mentioned, a stability or at least redispersibility suffi'^’ent for the purpose of application cannot be precluded, but the tests of the applicant have proved that said measures are quite inadequate for a longterm stability of pigmented oil-in-water emulsions. -7453 47 Thus, none of the above-mentioned publications mention the combination characteristic of the method according to the invention of a dispersion aid capable of rendering the particle surface oleophilic, a stabilizing agent capable of stabilizing the internal phase of the emulsion, and an emulsifier system compatible therewith which is capable of stabilizing the emulsion itself.

In an oil-in-water emulsion of the kind described in the present invention the retention of the particles in the internal phase and hence the stability of the suspension may be obtained, according to the invention, more specifically in the following manner: .

To render the particles, for example the pigment particles, oleophilic, i.e. they are preferentially wetted by oil rather than by water, they are ground, according to the invention, in the presence of one or more dispersion aids so that they are brought into said oleophilic state, which is a condition of the actual incorporation into the oil phase. Thus, for example pigment particles from preparatory processes or storage are often surrounded by a water film which must be displaced in the grinding process in the presence of the dispersion aid(s) in order to obtain good dispersion.

The dispersion aid(s) will usually be surfactant(s) such as nonionic surfactants e.g. alkyl polyethoxylates and alkyl arylpolyglycol ethers; ampholytic surfactants e.g. electroneutral salts of cation-active groups and anion-active groups, especially salts of fatty amines with fatty acids or polycarboxylic acids; anionic surfactants e.g. fatty alcohol sulphates, sulfimides, -8alkylarylsuifanates, especially alkylbcnzene sulfoiiates and alkyl' naphthalene sulfonates, phosphate esters, inetai naphthenates and metal salts of fatty acid' , and cationic surfactants e.g. quaternary ammonium compounds, alkyliraidazole salts and lecitin.

In addition to the dispersion aid the suspension of the finely divided solid particles ir. the oil also contains a stabilizing agent. The stabilizing agent may act electrostatically or sterically. The electrostatic .'.ly acting stabilizing agents act to impart to the individual particles an electric surface charge which will 10 contribute, if the original potential (zeta potential) of the particle is not sufficiently great, to an anti-flocculating effect by electrostatic repulsion. The electrostatically acting stabilizing agents may be selected from the same types of surfactants, apart from the non-ionic types, mentioned above as dispersion aids, although in any one eeuliiaii, the electrostatically acting stabilizing agent and the dispersion aid will not be the same compound.

It hat been found, however, that a most stable suspension is obtained if an cii-soluble sterically acting stabilizing agent is added to the oil phase, particularly during the grinding stage.

Such stabilising agents are, fcr example surface active soluble polymers with polar character, such as polymers of oxidized, unsaturated fatty acids and esters or ethers - Q -. ’thereof, partly polymerized esters of polycarboxylic acids, such as alkyds, and styrene-, isocyanate- and siliconemodified varieties hereof, acryl-modified and/or epoxidized oils and resins, aldehyde condensation products with amines and/or phenols, and polyethers and polyvinyl derivatives.-It has been found that effective stabilization is generally first observed in polymers having a molecular weight of about 150ό and increases with increasing molecular weight up to about 10,000, after which the effect may diminish.

It should be noted that a number of the said types of surfactants perform both electrostatic and steric stabilization, just as they may affect the particle surface itself, and according to circumstances the same or several different surfactants may therefore be used in addition to the dispersion aid.

Selection of surfactants depends inter alia, on the type of particles and the desired end product and may be determined by the person skilled in the art through tests. A preferred combination in the preparation of pigmented stains is a dispersion aid containing a hydrophobic group of cationactive character, such as an amine, possibly in the form of an amine salt, especially with a hydrophobic anion (electronneutral salt), or in the form of aa amine ester, such as a lecithin, in combination with a sterically stabilizing surface polymer mentioned above.

It is of Vital importance to the favourable progress of the -104534? o£4stee method that the particles are incorporated in a stable emulsion. This stability is provided by addition of one or more emulsifiers which produce steric and/or electrostatic forces between the individual particles of the internal phase (the oil phase) of the emulsion. In this connection it is of vital importance that said stabilization of the emulsion is not effected at the expense of the stability of the suspension in the internal phase, and it is therefore necessary to select emulsifiers that do not affect the stability of the oil phase produced by the dispersion agents and dispersion aids.

These emulsifiers, which may be of ionogenic or non-ionic type, can be added to one or both phases of the emulsion. As far as ionogenic (cE.ti -c.ic or anionic) types are concerned, the electrostatic repulsion between the internal phase drops is of substantial importance to the stabilization, while the effect of non-iorio types depends primarily on steric repulsion and is extensively pH-independent. The stability is further affected by the distribution of the surfactant between the two phases, and especially in the case of non-ionic types a so-called HLb value (hydrophilic-lipophilic 'balance) is often calculated for selection of the emulsifier which is best suited fcr a given type of oil.

To obtain electrostatic forces in the stabilization of the emulsion there may be added one or more surfactants acting in the external phase and in the boundary layer to the internal phase and selected from the group of ionogenic -1148347 emulsifiers and protective colloids, such as alkyl- aryl- and alkylsulfonates, amine and metal salts hereof, such as ealciumalkylarylsulfonates, carboxylic acids and polycarboxylic acids and their salts (soaps), such as polyacrylic acid salts with ammonia, amines and alkali metals, polyvinyl carboxylic acids and partial esters and/or salts thereof, cellulose, derivatives as well as polycondensed inorganic acids and salts hereof, such as sodium hexametaphosphate and lithium polysilicate.

To obtain sterically acting forces when stabilizing the emulsion there may be added one or more ionogenic surfactants of the type described above under electrostatic stabilization and/or non-ionic agents,, such as fatty acid- and fatty alcohol polyglycol ethers, polyethoxylated alkyl phenols, polycarboxylic acid esters and ethers, such as fatty alcohol succinates, sorbitol esters and ethers, sorbitan ether polyethoxylates, polyvinyl alcohols, polyethylene oxide and ethers and esters hereof as well as cellulose derivatives, such as hydroxyethyl cellulose.

It has been found that a combination of a non-ionic emulsifier of the correct HLb value (for example of the alkylphenol polyethylene oxide adduct type) added to the internal phase, and a minor amount of anionic surfactant of the protective colloid type,. for examplepolyacrylate or a polyvinylmaleinate, added to the external phase is' particularly suitable for stabilization of the emulsion itself as it functions satisfactorily for example in the suspension of pigments in the internal -1245347 phase of emulsions of vegetable oils and their synthetic analogs or derivatives thereof and does noi affect the particle stability in the inner phase adversely. Said anionic component may also act to adjust a suitable viscosity and for chelation of heavy metal ions which may othsindse as contaminants destroy the electrostatic stabilization, however these functions may also be performed by separate components of cationic, anionic or non-ionic nature, such as sodium tripolyphosphate, •»0 To improve stability, especially when the suspension is employed in highly diluted state involving a risk of stratification in the case of great differences in density, there may also according to the invention be added to the oil phase one or more density-equalizing agents, including light T5 liquids, such as aliphatic and aromatic hydrocarbons, and heavy liquids, met as halogenated hydrocarbons, for example ethylene dichloride, uris-2,3-dibroao propylphosphate and chloro paraffins. It is also possible tc add solid substances, for example light substances, such as wax au-t microscopic hollow glass balls (micro-epfesres/, and heavy substances, ruch a,s solid chloro paraffin and antimony trioxide. These may serve at the same time as flamersterdantY.

Applicable pigments are for example oxides and insoluble salts of earth alkali metals and metals in the transition series, for example iron oxides, chromium oxides, sine oxide, barium sulphate, titanium dioxide, calcium carbonate; aluminium and magnesium silicate; other oxides and elements, .for example silicon dioxide, carbon black, aluminium powder and zinc dust, as well-as organic compounds, for instance heliogen green, phthalocyanine blue, benzidine yellow and perylene red. The type of pigment, however, is not critical to the invention.

Finally, other protectants of various kinds may be added'to the oil or water phase, and these may for example also be in the form of finely divided solid particles. Examples of other protectants include biocides, such as fungicides, for example tetrachloroisn10 phthalonitrile, copper-8-hydroxyquinoline, tributyl tin oxide and derivatives thereof; preservatives, such as sodium pyridin-thion-1 and 2,2-dibromoglutarodinitrile; insecticides, such as lindane or endosulfane, IH-reflecting agents and specific UV-absorbing agents, just as oil soluble pigment binders may be added to the oil phase, for instance oxidative drying, possibly modified oils. However, it has surprisingly been found, that the requirement for specific UV-absorbing agents in the pigmented stains described is very small as they cause extremely good penetration and distribution of the pigment in the treated wood surfaces. 4334? To the water phase can he added water soluble t.::- water dispersible hinders, for exanple polyacrylate dispersions, styrene-butadiene-polymer dispersions or polyfinylacetate dispersions. If desired, there may also be added an oxidation catalyst (siccative) which is complexed in a foi'ffi so that the equilibrium concentration of the free catalyst in the external phase is so small that the stabilizing system of the emulsion is /.-.ot affected noticeably hereby. and, if desired, a stabilizer and/or an antioxidant to stabilize the siccative.

The stable’ pigment suspensions prepared according to the invention present the additional advantage that they are well suited for obtaining reproducible colour tints. When cogrinding pigments of different colours in the oil phase a co-flocculation has previously been observed, vhioh impedes a precise and reproducible shading. It has beer. found. that by mixing finished pigment suspensions of the type described as well as by grinding together the pigments in the oil phase by the metho! according to the invention, this co-fiocculation is eliminated, whereby a desired tint can be obtained in a simple manner.

The mixture proportion between the constituents asy vary within wide limits d·--pending on the desired end product and not least on the kind of solid particles.

The oil-in-water emulsion raav thus contain from 1 co 70 percent by weight of oil, but will usually contain from scout 20 to 30 percent by weight. -1545347 ' For preparing, by way of example, a pigmented stain, a paste of the following composition will generally he ground first: . 1 - 75 parts by weight of pigment 0.1-10 ” ’ dispersion aid (pigment wetting agent) - 45 ** stabilizing agent —'45 density-equalizing agent the sum of the constituents being 100 parts by weight.

For 50 parts by weight of this paste the* following is subsequently used:. -.650 parts by weight - 50 - 5 ” ” 11 0-10 of pigment binder emulsifier (stabilizing agent for the emulsion) 11 siccative and stabilizer therefor biocides and other secondary materials. 0.1 - 50 parts by weight of stabilizer which may also perform other functions (calculated as active substance) · 11 pigment binder, however not exceeding 50 percent by weight of the water phase, biocides and other secondary materials 400 II II as well as demineralized water up to 1000 parts by weight. · The invention is illustrated in greater detail by means of the examples stated below: '. , -1645347 EXAMPLE 1 Preparation of a pigmented stain.

By dispersion on a pearl mill there was pi’epar-ed an orange paste'by grinding 40 parts by weight of Transparent iron oxide red (e.g. VN 188, which is an orange hydrophilic pigment sold by Siegle & Co.), 5 parts by weight cf dispersic. aid {pigment vetoing agenti e.g.’Disperbyk (Trade Mark), which is an electroneutral salt prepared by reacting an alhylol amine salt with a polycarboxylic acid, sold by Byk-Zallinckrcifc, and. 55 parts by weight of soybean oil alkyd having an oil length cf 65% (sterically stabilizing agent for the pigment) , The dispersion took plica at ambient, temperature to a particle size of max 20 /λ. g of this paste was mixed at ambient temperature for about 10 minutes with 200 g of 100 percent (sclve-re-iree) linseed oil alkyd having an oil length of about 80% which acts as binder, 12 g of nonylphenoldodecaethoxylate (sterically stabilizing non-ionic emulsifier), 1.2 e of cobalt naphthenate (6% Co - siccative), 0.8 g of a 38% solution of o-phenanthroline in butyl glycol, sold by Vanderbilt lo. under the trade name Activ 8 (stabilizer for siccative against hydrolysis) as well as 2 g of methylethylketoxime (volatile antioxidant acting as anti-skinning agent).

The 266 g mixture thus obtained, which may ba regarded as a fluid oil paint, was dispersed at ambient temperature for about 10 minutes in a mixture of 210 g cf demineralized water -1745347 and 30 g of 15% polyvinylmaleic acid alkylglycolesterammonium salt (Thickner LN),' which is an anionic stabilizer acting also as chelating agent and thickener and. which was first mixed for about 5 minutes with another 60 g of demineralized water. By said process there was obtained 566 g of pigment dispersion having the character of an emulsion paint to which was added vzhile stirring 434 g of demineralized water, to which biocides and other protective agents may have been added.

The stain (1000 g) thus obtained has at 20°C a viscosity of 12 cP, pH 7.8, specific gravity 1.083. It is easily prepared and, at low cost, it has excellent penetration ability when applied to wood surfaces and causes no air pollution in use.

It is stable on standing and shows no tendency towards sedimentation of the pigment, even after a storing period of 14 months. The stain also has excellent freeze-thaw stability.

For example, no product changes were observed after a standard test comprising 3 freezings to -18°C with intermediate thawings.

In the same manner stains have been prepared using pigments with other colours, such as TO 088, yellow iron oxide pigment and TO 288 red iron oxide pigment, carbon black and phthalocyanine blue, ;and other dispersion aids, such as Texaphor 963, electro neutral pigment wetting agent, . : and' lecithin, as well as other stabilizing agents, such as tall oil alkyds. Stains of the same excellent quality were obtained. -184834? By way of comparison identical stains ha/e prepared, the dispersion aid characteristic of the invention; however, being omitted. In all cases the pigments wa-e precipitated after standing for a short period.

The protective effect of a number of stains prsparsd as stated above for treatment of wood surfaces has also been tested.

Under accelerate, i test conditions as regards weaUtr the products described have exhibited a surprisingly high degree of weather resistance and have inter alia, proved to ba superior to current types of stain on alkyd-solvent base . well as on acryl dispersion base under otherwise identical conditions as regards degree of pigmentation, and concentration of binder. examples Preparation of c pigmented stain.

By dispersion on a pearl mill a black paste '.-’as prepared from 15 parts by weight of carbon -i· . (Printer 30ϋ:’ Printex'' is a Trade Mark), 4 parts by weight of Bentonite (thickii’vi·.- ‘03 in white spirit), 1 cart by weight of dispersion aid {Pisc-wrfcyk), 35 parts by weight of linseed oil alkyd (stabilizing :/)· and 45 parts g0 by weight of unite spirit (density-equalizing -_gent). g of this paste was treated analogously with the paste prepared in Example 1, and there was obtained a stable stain having a specific gravity of 1.05, pH 7.8, and viscosity 12 cP. Said stain also showed excellent pere/tr-atiO;; ability -1945347 and was stable even in a case of great additional thinning.

EXAMPLE 3 A polish was prepared by grinding together 1 part by· weight of diatomite, 8 parts by weight of dearomatized white spirit 1 part by weight of alkyd, 0.1 parts by weight of linoleyltrimethylene diamine-dioleate (dispersion aid) 0.5 parts by weight of polyethylene glycol dioleate (PEG 400-dioleate), which was subsequently emulsified in 89.4 parts by weight of water containing 0.0025 parts by weight of polyacrylic acid ammonium salt Acrysol ASE95 (anionic stabilizer). The obtained odourless composition was stable on prolonged standing with no tendency towards sedimenta'tion.

EXAMPLE 4 Preparation of a pigmented stain parts by weight of black pigment (Printex 300) were ground analogously with Example 1 with 37·3 parts by weight of tall oil alkyd S 84 (sterically stabilizing agent), prepared by esterification of tall·oil fatty acids with pentaerythritol and 11% of isophthalic acid, 2 parts by weight of purified soyabean lecithin (dispersion aid), 3 parts by weight of alkylphenopolyglycol ether (Vase, sold by Berol Kemi), 6 parts of Bentonite paste (10% bentonite, 85% white spirit and 5% ethanol), 1.5 parts of methylethylketoxime and 35-2 parts of white spirit (Varnolene).

Analogously, a blue paste was prepared from Hostapermblau BFL (phthalocyanine blue) - Hostaperm is a Trade Mark - and the same constituents in the same quantities except that there was used 44 parts by weight of Varnolene and 28.5 parts by weight of S 84. -204534 7 0.35 parts by weight of this black past·· mm 4. '>'6 part'·, by wi; ight of this blue paste were mixed in a Covli-g uissoivcr for about 10 minutes in 20 parts by weight 5 -34, 2 parts by weigni of Vase, 0.4 parts by weight of methylethyiketoxime, 0.25 parts by weight of Co-aetiv (which is a mixture of 40 parts by weight of Activ 8, of Example i, 20 parts by weight cf cobalt naphthenatc (185» Co) and 40 n’rts by weight of butyl glycol.! as c- ii as 1.8 parts of Ji 54 D,: which is a dispersion of 2,3;t;l-,tetrachlorisophthalonitrilo in a glycol ether.

Further, 20,9 parts fcy weight of water. 0.2 parts by weight of NH,j and 7.5 parts by weight of 335» Thickner Li·; were mixed for 5 minutes.

The first prepared mixture was then poured in :;· .:·.·! mixture and was mixed for 3 minutes, after which 39.95 parts by weight of water and 2 parts by weight of monopropyieneglyccl < freeze-thaw stabilizing agentl were added.

There was obtained a dark blue pigmented sta:r having the same excellent properties as obtained in Example ·.

Claims (17)

1. A method of preparing a liquid low viscosity oil-in-water emulsion comprising from 1 to 40# by weight of oil wherein the oil phase contains a stable suspension of finely divided solid particles, which method comprises grinding the finely divided solid particles in the presence of one or more dispersion aids to render the surfaces of the particles oleophilic, suspending the particles in the oil before, during or after grinding, the suspension being stabilized by inclusion therein of one or more stabilizing agents, and emulsifying the stabilised suspension in an aqueous medium in the presence of one or more compatible emulsifiers.

2. A method as claimed in claim 1, wherein the dispersion aid is selected from non-ionic surfactants, ampholytic surfactants, anionic surfactants and cationic surfactants.

3. A method as claimed in claim 2, wherein the non-ionic ' surfactants are selected from alkyl polyethoxylates and i alkylarylpolyglycol ethers; the ampholytic surfactants are i eleotroneutral salts of cation-active and anion-active groups; the anionic surfactants are selected from fatty alcohol sulfates, sulfimides, alkylaryl sulfonates, phosphate esters, metal naphthenates and metal salts of fatty acids; and the cationic surfactants are selected from quaternary ammonium compounds, alkylimidazole salts and lecithin.

4. A method as claimed in claim 3, wherein the electroneutral salts of cation-active and anion-active groups are salts of fatty amines with fatty acids or polycarboxylic acids. -224534? 5. A method as claimed in claim 3, whexein ρ e a Iky 1 aryl su 1 f ona tes are selected from alkylbenzene sulfc.aTes and a 1 Ir inapii thalene sulfonates. A method as claimed in any one of clvims 1 to 3» wherein the dispersion aid is a compound containing a hydrophobic group and having a cation-active character. v, a method as claimed in dais; 6, wherein the compound is an amine, optionally in the form of a salt, or an amino ester. 8. A method as claimed in claim , wherin the compound is an amine salt with a hydrophobic anion (electron eutrai salt) or lecithin.

5. 9. A method as claimed in any one cf claims 1 to 8, wherein the stabilizing agent is one or more of the surf,-. cbants ΐίιat may be used as a dispersion aid or more surface acti ve soluble polymers having a polar group. 10. A method as claimed in claim 9, wherein be.-· surface active polymers are selected from polymers of oiidiz ed unsaturated fatty acids and esters or ethers thereof, partly polymerized esters of polycarboxylie acids and styrene-, isocyanat--, and siliconemodified varieties thereof, aeryl modified e.nd/or epoxidized oils and resins, aldehyde condensation products with amines and/or phenols, and polyvinyl derivatives. 11. A method as claimed in either claim 9 tr claisj 10 9 wherein the stabilizing agent is a surface active pc_ yn:cr having a molecular weight of from 1,500 to 10,000.

6. 12. A method as claimed in any one of claims 1 to 11, wherein a non-ionic emulsifier is added tc the cii n!j, asi to stabilize the emulsion and a minor amount of an ar.ionic sur f·:.otars of the protective colloid type is added to the wetor phase -2145347 .

7. 13- A method as claimed in any one of claims 1 to 12, wherein an agent equalizing the difference in density between the internal and external phases is further added to the oil phase.

8. 14. A method as claimed in any one of claims 1 to 13, wherein the finely divided solid particles are particles of pigment.

9. 15· A method as claimed in claim 14 wherein an oil soluble pigment binder is further added to the oil phase.

10. 16. A method as claimed in claim 15, wherein an oxidative drying oil is used as pigment binder.

11. 17. A method as claimed in claim 16, wherein the oxidative drying oil is a modified oil.

12. 18. A method as claimed in claim 17, wherein a water soluble or water dispersible pigment hinder is further added to the emulsion.

13. 19· A method as claimed in claim 18, wherein the pigment hinder is an acrylic resin.

14. 20. A method as claimed in any one of claims 1 to 19, wherein there is further added an oxidation catalyst (siccative) which is complexed in a form so that the equlihrium concentration of the free catalyst in the external phase is so small that the stabilizing system of the emulsion is not noticeably affected hereby.

15. 21. A method as claimed in claim 1 substantially as hereinbefore described.

16. 22. Pigmented stain, prepared by a method as claimed in any one of claims 1 to 21.

17. 23» Polish or abrasive, prepared hy a method as claimed in any one of claims 1 to 21-.