WO2004041942A1

WO2004041942A1 - Colloidal dispersion and cerium or cerium and titanium, zirconium, aluminium or rare earth coloured powder, method for preparing same and use thereof

Info

Publication number: WO2004041942A1
Application number: PCT/FR2002/003657
Authority: WO
Inventors: Christophe Eychenne-Baron; Jean-Yves Chane-Ching; David Fauchadour
Original assignee: Rhodia Electronics And Catalysis
Priority date: 2002-10-24
Filing date: 2002-10-24
Publication date: 2004-05-21
Also published as: AU2002361301A1

Abstract

The invention concerns a colloidal dispersion comprising particles of a cerium compound or of a cerium compound and of a compound of at least another element M selected among titanium, zirconium, aluminium and rare earths other than cerium. The invention is characterized in that it comprises a colorant bound to said particles via a chemical function (Rs) of said colorant which is capable of creating between the particles and the colorant a bond by complexing, adsorption or of electrostatic type. In accordance with a second embodiment, the inventive dispersion further comprises a coupling agent bound to the particles via a chemical function (R's) which is capable of creating between the particles and the colorant a bond by complexing, adsorption, of electrostatic type or covalent and a colorant covalently bound to said coupling agent. The inventive powder is obtained by drying the dispersion. Said dispersion and said powder can be used for preparing polymer materials, in cosmetic compositions, in coatings, more particularly in surface coating formulations.

Description

COLLOIDAL DISPERSION AND COLORED POWDER OF CERIUM OR

CERIUM AND TITANIUM, ZIRCONIUM, ALUMINUM OR EARTH

RARE, THEIR PREPARATION PROCESS AND THEIR USE

The present invention relates to a colloidal dispersion and a colored powder of cerium or cerium and of another element M chosen from titanium, zirconium, aluminum and rare earths other than cerium, their preparation process and their use .

Cerium soils, especially tetravalent cerium soils, are well known. Furthermore, cerium soils in combination with another element can be of great interest, for example for applications in cosmetics, optics or in the field of phosphors. Because of their numerous potential applications, it is also sought to obtain soils with specific properties, for example with anti-UV properties, and capable of developing coloration, for example in polymers. There is therefore a need for colored floors. The object of the invention is therefore to provide such colored soils. For this purpose and according to a first embodiment, the dispersion of the invention is a colloidal dispersion in a continuous phase of particles of a compound of cerium or of '' a cerium compound and a compound of at least one other element M chosen from titanium, zirconium, aluminum and rare earths other than cerium, and it is characterized in that it comprises a dye bound to said particles via a chemical function Rs of said dye which is capable of creating between the particles and the dye at least one bond by complexation, by adsorption or of the electrostatic type.

According to a second embodiment of the invention, the dispersion of the invention is a colloidal dispersion in a continuous phase of particles of a compound of cerium or of a compound of cerium and of a compound of at least one other element M chosen from titanium, zirconium, aluminum and rare earths other than cerium and it is characterized in that it comprises: - a coupling agent linked to said particles via a chemical function R's of said agent which is capable of creating between the particles and the agent a bond by complexation, by adsorption, of the electrostatic or covalent type; - a dye linked to said coupling agent by a covalent bond.

Other characteristics, details and advantages of the invention will appear even more completely on reading the description which follows, as well as various concrete but nonlimiting examples intended to illustrate it. For the remainder of the description, the expression colloidal dispersion or sol of a cerium compound, or of a cerium compound and of another element M mentioned above, designates any system made up of fine solid particles of colloidal dimensions, c '' is to say particles whose size is generally between 1nm and 500nm, more particularly between 2nm and 100nm. These particles are based on oxide and / or hydrated oxide (hydroxide) of cerium and of the other element M, suspended in a liquid phase, said particles possibly also containing, possibly, residual amounts of ions bound or adsorbed such as for example acetates, citrates, nitrates, chlorides or ammoniums. The percentage of these ions bound X or possibly X + Y in the case of two ions, expressed in molar ratio X / Ce or (X + Y) / Ce can vary for example between 0.01 and 1.5, more particularly between 0,01 and 1. It will be noted that in such dispersions, the cerium and the other element M can be either completely in the form of colloids, or simultaneously in the form of ions or polyions and in the form colloids.

By rare earth is meant the elements of the group constituted by ryttrium and the elements of the periodic classification with atomic number included inclusively between 57 and 71.

The dispersion of the invention is based on cerium generally present in the form of cerium IV, but this dispersion may possibly contain cerium in the oxidation state III. In this case, the level of cerium III is generally at most 50%. It is expressed here and for the whole of the description by the atomic ratio Ce I Il / Ce total. The level of cerium III can more particularly be at most 35%, in particular in the case of a dispersion of cerium and another element M, and very particularly at most 10%. Furthermore and according to the different variants of the invention, it can be at least 0.5%. This rate may more particularly be at least 1% and even more particularly at least 1.5%.

In the case of a dispersion containing an element M, the amount of this element is generally at most 50%, preferably at most 20%, this amount being expressed by the ratio moles of element M / sum of moles of element M and cerium. Element M can be present in different states oxidation. The invention also applies of course to dispersions containing several elements M.

The dispersion of the invention can be presented according to two embodiments. The first mode will now be described more precisely.

The main characteristic of the dispersion according to this mode is the presence of a dye bound to the particles of the dispersion. The term “dye” is intended to mean any compound exhibiting absorption or emission properties of light in the visible light range or in a wider range, ranging from near ultra-violet to near infrared. The bond between the dye and the particle can be of different types. It can first of all be a bond by chemical complexation between the dye and a cation present on the surface of the colloidal particle. This connection can also be of electrostatic nature between the dye and the surface of the colloidal particle, for example of positive charge. Finally, this connection can be made by adsorption between the dye and the surface of the particle. It will be noted that the three types of bond given above can coexist. These connections can also be demonstrated by different techniques, for example by determination of adsorption curves according to techniques known to those skilled in the art; by chemical analyzes of centrifugation or ultracentrifugation supernatants or by spectroscopic techniques of the Raman or infrared type on colloids separated from their liquid phase by ultracentrifugation or finally by measurements of electrophoretic potentials of the dispersions. The dye has a chemical function Rs which is capable of creating between the particles and the latter a bond of the type described above.

As Rs function of this type, mention may be made of the carboxyl - CO ₂ H, or carboxylate - CO ₂ M 'functions; sulfonate - -SO ₃ M ', sulfosuccinate - CO ₂ - CH ₂ - CH (SO ₃ M') - CO ₂ H, M 'denoting a metal, in particular an alkali metal or the sulfonic acid function - SO ₃ H or sulfate - O - N / A. Thus, there may be a bond by chemical complexation between the carboxyl, carboxylate, sulfonate or sulfonic group in ionized form and a cation present on the surface of the colloidal particle. An electrostatic connection can also be established between the ionized - COO ^" or - SO ₃ ^{" group} of the dye and the surface of the positively charged colloidal particle. More particularly, the Rs function can be a carboxylate function present with an amine function. The dyes used can of course have several of these functions of the same type or of different types in combination. Mention may thus be made of the particular case of dyes having both one or more carboxylate functions in combination with one or more amino functions.

The dye of the dispersion of the invention can be of any type insofar as it has the abovementioned Rs function. Water-soluble dyes can be used very particularly.

Dyes which may be suitable in the context of the present invention are given below by way of examples, the names and numbers given here and in the following description are those of the Color Index (Cl).

Thus, the dye can be chosen from the azo family, that is to say compounds comprising a group - N = N—. Among the dyes of this family, one can use the monoazo Cl N ° 16035, Cl N ° 15985, Cl N ° 15510, Cl N ° 15850, Cl N ° 15585, Cl N ° 12085 or the diazo for example Cl N ° 20170 . The dye may be an element of the xanthene family, for example Rhodamine B (Cl N ° 45170) or even Cl N ° 45430. One can also mention the dyes of the indigo family such as Cl N ° 73015. Dyes which are suitable are also those of the triphenylmethane type such as Erioglaucine (Cl N ° 42090) or Cl N ° 42053 or also Cl N ° 42090.

Mention may be made of the dyes of the family of pyrazolones Cl No. 19140 or else orange B, those of the family of anthraquinone: Cl No. 61570 for example, those of the family of pyrene: Cl No. 59040 in particular, quinolines: Cl N ° 47005 for example or nitro type dyes like Cl N ° 10315.

The dispersion of the invention can also be presented according to a second embodiment which will now be described.

The main characteristic of this second mode is the presence of a coupling agent linked to the particles of the dispersion and of a dye which is linked to the coupling agent.

The bond between the coupling agent and the particle is of the same type as that which was described above for the first embodiment as regards the particle-dye bond, that is to say that it is of a bond by chemical complexation between the coupling agent and a cation present on the surface of the colloidal particle or also of an electrostatic bond between the coupling agent and the surface of the colloidal particle, for example of positive charge or finally of an adsorption bond between the coupling agent and the surface of the particle. However, in the case of this second embodiment, the bond between the coupling agent and the particle can also be covalent. This covalent bond can be demonstrated by spectroscopic techniques of the Raman, NMR and infrared type. Again, these different types of link can coexist. This bond is established by a chemical function R's which is of the same type as the function Rs mentioned above. What was previously described about Rs therefore also applies here. It will however be added that in the case of the coupling agent, the R's function can also be a phosphonate - PO (OH) ₂ or phosphinate = PO (OH) or phosphate - O— PO (OH) function, in particular in the case where the bond with the particle is of covalent type.

Furthermore, according to this second embodiment, the dye is linked to the coupling agent by a covalent bond.

In order to ensure the dye-coupling agent covalent bond, these two elements must have specific chemical functions. More specifically, the coupling agent must be the remainder of a coupling compound comprising a chemical function Rc capable of reacting to form a covalent bond. By “the remainder of a coupling compound” is meant the molecule resulting from a coupling compound but which no longer contains the atom or atoms which were eliminated during the chemical reaction which led to the formation of the bond covalent. It will be noted that the coupling compound may also comprise a chemical function R's capable of reacting to form a bond by complexation, by adsorption or of the electrostatic or covalent type with the surface of the particle. Likewise, the dye is the remainder of a dye compound comprising a chemical function R'c capable of reacting with the coupling compound to form a covalent bond. By “the remainder of a coloring compound” is meant in the same sense as above the molecule resulting from the coloring compound but which no longer contains the atom or atoms which were eliminated during the chemical reaction which led to the formation of covalent bond.

The abovementioned chemical functions Rc and R'c may more particularly be an amino group, an aldehyde or a halogen. The amino group may more particularly be - H ₂ . The halogen can more particularly be chlorine. The coupling compound can more particularly be a compound of formula:

Z -, - R1-Z2 in which R is an alkyl group comprising from 1 to 12 carbon atoms, Zi, which corresponds to the function R's, is a group - CO ₂ H, carboxylate - CO ₂ M 'or —SOsM', M 'denoting a metal, in particular an alkali metal, Zi possibly also being a phosphate or phosphonate group, Z ₂ denotes a halogen or a group - -NHR ₂ , or - NR3R2, or - NH ₄ ⁺ , R2 and R ₃ , identical or different, denoting a hydrogen or an alkyl group comprising from 1 to 8 carbon atoms.

The group Ri can be linear or branched. It can more particularly have a number of carbon atoms between 4 and 10 or even more particularly between 4 and 8.

Z ₂ , which corresponds to the Rc function, can in particular be chlorine or NH ₂ .

The coupling compound can in particular be an amino acid, more particularly an aliphatic amino acid. It may especially be a C4-C ₁ 0 acid and preferably a C ₄ -Cβ acid. As an example of an acid, mention may be made of aminocaproic acid.

The coloring compound forming part of the composition of the dispersion of the invention can be any type of compound having properties of absorption or emission of light in the range of visible light or in a wider range, ranging from close ultraviolet to near infrared, to the extent, moreover, where it exhibits the abovementioned R'c function.

The chemical functions Rc and R'c of the coupling compound and of the coloring compound are chosen so as to be able to create between the coupling compound and the coloring compound a covalent bond. By way of example, mention may be made of the coloring compounds chosen from the monoazo family such as Cl No. 12085 or Cl No. 15585, those from the xanthene family such as Cl No. 45370: 1, Cl No. 45425: 1, Cl No. 45425 and Cl No. 45410 and also those of the family of anthraquinones such as Disperse Violet 1. The functions Rc and R'c are chosen from each of the coupling compound and the coloring compound so as to be able to create between these compound the desired covalent bond. They can thus be more particularly chosen from the Rc / R'c amine / halogen, halogen / amine, amine / aldehyde or aldehyde / amine pairs. According to a variant of the second embodiment of the invention, the dye may also comprise a chemical function Rs which is capable of creating between the particles and the dye a bond by complexation, by adsorption or of the electrostatic type. In this case, the dye is linked to the particles of the dispersion both by means of the coupling agent and by a chemical bond of the same type as that which has been described in the case of the first embodiment of the invention. The description which has been made on this bond and on the chemical function Rs therefore applies here.

As a dye or coloring compound capable of entering into the composition of the dispersion according to this variant, mention may be made of those of the azo type such as Cl N ° 15585 with sulfonate and chlorine functions or Cl N ° 17200 (Acid red 33) with sulfonate functions and - NH ₂ or the compounds of formula (1) of EP-A-437184 or of formula (1) of WO 97/30125, the brilliant Cibacron Red 3B-A or the Procion Red MX-5B (ref. 22845-1 and 40436-5 respectively from the company Aldrich) with sulfonate and chlorine functions.

Mention may also be made of products of the anthraquinone type with sulfonate and NH _{2 functions} such as Reactive Blue 2 or Procion Blue HB Ref 24 222-5 from the company Aldrich or brilliant blue PX3R.

The concentration of dye in the dispersion of the invention may vary. Generally the ratio R: moles of dye / moles of cerium or moles of dye / moles of cerium and of element M is between 0.001 and 0.1, preferably between 0.001 and 0.01. Expressed as a mass, the ratio R ′: mass of dye / mass of cerium oxide or mass of dye / mass of cerium oxide and of oxide of element M is between 0.001 and 0.20, preferably between 0.001 and 0.075.

The concentration of coupling agent can also vary. It can be between 0.01 and 0.6 mole of coupling agent per mole of cerium or of cerium and of element M.

It should be noted here that although, preferably, all of the dye present in the colloidal dispersion is bound to the particle by the bonds of the type described above and, likewise, all of the coupling agent, it would not be outside the scope of the invention if part of the dye or coupling agent was not. Thus, the mass ratio R ¹ : bound dye / (bound dye + free dye) is greater than 50%, preferably 80% and;! the same is true for the mass ratio R ² : bound coupling agent / (bound coupling agent + free coupling agent).

The dispersions according to the invention can be aqueous dispersions, the continuous phase being water, or dispersions in a continuous phase which is an organic phase.

In the latter case, the organic phase can be based on a liquid or a mixture of liquids of very varied nature. This solvent can be an inert aliphatic, cycloaliphatic hydrocarbon, or a mixture thereof, such as, for example, petroleum or mineral spirits which may also contain aromatic components. Mention may be made, by way of indication, of hexane, heptane, octane, nonane, decane, cyclohexane, cyclopentane, cycloheptane and liquid naphthenes. Aromatic solvents such as benzene, toluene, ethylbenzene and xylenes are also suitable as well as petroleum fractions of the ISOPAR or SOLVESSO type (trademarks registered by the company EXXON), in particular SOLVESSO 100 which essentially contains a mixture of methylethyl and trimethylbenzene, and SOLVESSO 150 which contains a mixture of alkyl benzenes, in particular dimethylethylbenzene and tetramethylbenzene.

It is also possible to use chlorinated hydrocarbons such as chloro or dichlorobenzene, chlorotoluene, as well as aliphatic and cycloaliphatic ethers such as diisopropyl ether, dibutyl ether and aliphatic and cycloaliphatic ketones such as methylisobutylketone , methyl ethyl ketone, diisobutyl ketone, mesityl oxide.

It is also possible to use ketones, such as acetone, aldehydes, nitrogenous solvents such as acetonitrile, alcohols, acids and phenols. Esters can also be considered. Mention may be made, as esters which can be used, in particular those resulting from the reaction of acids with C1 to C8 alcohols and in particular secondary alcohol palmitates such as isopropanol. The acids from which these esters are derived can be aliphatic carboxylic acids, aliphatic sulfonic acids, aliphatic phosphonic acids, alkylarylsulfonic acids, and alkylarylphosphonic acids having about 10 to about 40 carbon atoms, whether natural or synthetic. . By way of example, mention may be made of tall oil fatty acids, coconut oil, soybean, tallow, linseed oil, linoleic acid, pelargonic acid, capric acid, lauric acid, myristic acid, dodecylbenzenesulfonic acid, 2-ethylhexanoic acid, naphthenic acid, hexoic acid, toluene-sulfonic acid, toluene-phosphonic acid, lauryl- acid sulfonic, lauryl-phosphonic acid, palmityl-sulfonic acid, and palmityl-phosphonic acid.

In the case of the dispersion of the invention in organic phase with an organic solvent of the type of those mentioned above, it also comprises an amphiphilic compound.

This compound can be chosen first of all from polyoxyethylenated alkyl ethers of carboxylic acids. By this is meant the products of formula: R3- (OC2H4) _n -O-R4 in which R3 is a linear or branched alkyl radical which may especially comprise 4 to 20 carbon atoms, n is an integer which can range for example up to to 12 and R4 is a residue of carboxylic acid such as for example -CH2COOH. It is of course possible to use these products as a mixture. By way of example, mention may be made for this type of amphiphilic compound of those sold under the brand AKIPO® by Kao Chemicals.

The amphiphilic compound can also be chosen from polyoxyethylenated alkyl ether phosphates. The polyoxyethylenated alkyl phosphates of formula:

R5-Q- (CH2-CH2-O) n-P- (OMι) 2

II o or the polyoxyethylenated dialkyl phosphates of formula:

R6-O- (CH2-CH ₂ -O) _n I R7-O- (CH2-CH2-O) _n -P-OM 1

II O

in which R5, R6, R7, identical or different, represent a linear or branched alkyl radical, in particular from 2 to 20 carbon atoms; a phenyl radical; an alkylaryl radical, more particularly an alkylphenyl radical, in particular with an alkyl chain of 8 to 12 carbon atoms; an arylalkyl radical, more particularly a phenylaryl radical; n the number of ethylene oxide can vary from 2 to 12 for example; Mi represents a hydrogen, sodium or potassium atom. The radical R5 can in particular be a hexyl, octyl, decyl, dodecyl, oleyl, nonylphenyl radical.

As an example of this type of amphiphilic compound, mention may be made of those sold under the brands Lubro hos® and Rhodafac® sold by Rhodia and in particular the products below:

- poly (oxy-ethylene alkyl (C8-C10) ether phosphates Rhodafac® RA 600

- poly-oxyethylene tri-decyl ether phosphate Rhodafac® RS 710 or RS 410

- poly-oxy-ethylene oleocetyl ether phosphate Rhodafac® PA 35

- poly-oxy-ethylene nonylphenyl ether phosphate Rhodafac® PA 17 - poly (oxy-ethylene nonyl (branched) ether phosphate Rhodafac® RE 610

The amphiphilic soil compound of the invention can also be chosen from dialkyl sulfosuccinates, and in particular alkaline dialkyl sulfosuccinates such as sodium dialkyl sulfosuccinates, that is to say the compounds of formula R8-OC (O) -CH2-CH (Sθ3M2) -C (O) -O-Rg in which Rδ and Rg, identical or different, represent an alkyl radical from C4 to C14 for example and M2 is an alkali metal or a hydrogen.

As compounds of this type, mention may be made of those sold under the brand Aérosol® by the company Cyanamid. As other amphiphilic compounds which are suitable for the present invention, mention may also be made of quaternary ammonium compounds. Mention may more particularly be made of mono, di or tri alkyl ammonium compounds, one of the radicals attached to the nitrogen atom being able to be an alkyl radical comprising from 1 to 3 carbon atoms, including these alkyl radicals from 1 to 3 carbon atoms carrying inert substituents, for example halogen, acetate, methylsulfate, etc. one of the other radicals which may be an alkyl radical from C4 to C20-

Finally, it is possible to mention, as amphiphilic compounds, fatty carboxylic acids such as oleic acid, stearic acid and its isomers. The choice of the amphiphilic compound is made according to the nature of the organic liquid phase. More precisely, this choice is made by adapting the hydrophilic / lipophilic balance of the amphiphilic compound to the hydrophilic / lipophilic character of the organic phase. In other words, the more polar the solvent entering into the constitution of the organic phase, the more hydrophilic the amphiphilic compound will be.

The proportion of amphiphilic compound relative to cerium oxide is adjusted so as to obtain a stable dispersion; it is generally between 0.5 and 10, preferably between 1 and 4 molecules per nm ² of cerium oxide surface, assuming a surface per complexing head of the amphiphilic compound for the cerium cation of the colloidal particle between 10 and 80Â ² .

It will be noted that in the case of dispersions containing an amphiphilic compound, the particles therefore present on the surface this amphiphilic compound with the dye and / or the coupling agent. Still in the same case, the dye is preferably a fat-soluble dye.

According to a particular embodiment, the continuous phase of the dispersion can be constituted by a water / organic solvent mixture miscible with water or also by an organic solvent miscible with water. As an example of such solvents, mention may be made of certain alcohols such as methanol or ethanol, glycols such as ethylene glycol, certain acetate derivatives of glycols such as ethylene glycol monoacetate, glycol ethers, or also selected solvents. among polyols or ketones. In the case of this particular embodiment, the dispersions may not contain an amphiphilic agent.

The dispersion of the invention can have a variable concentration which, generally, is at least 10 g / l. This concentration is expressed as oxide and taking into account the sum of the cerium oxides and, where appropriate, of the other or other elements M mentioned above. This concentration can more particularly be at least 50 g / l and even more particularly at least 150 g / l.

The sizes of the colloidal particles which constitute the soles or dispersions of the invention are also liable to vary over a wide range. Thus, the particles can have an average diameter in particular between 1 and 500 nm, more particularly between 3 and 300 nm and even more particularly between 2 nm and 100 nm. This diameter is determined by photometric counting from an analysis by METHR (High Resolution Transmission Electron Microscopy). The process for preparing the dispersions of the invention will now be described.

In the case of the first embodiment of the invention, the method is characterized in that a starting cereal compound or a cerium compound and at least one other element are added to a starting colloidal dispersion M mentioned above a dye comprising a chemical function Rs of the type which has been described previously.

Any suitable colloidal dispersion can be used as the starting dispersion. Mention may thus be made, as suitable dispersions, of those described or obtained by the methods described in patent applications EP-A-206906, EP-A-208580, EP-A-208581, EP-A-239477, EP-A-700870 and FR-A-2801298. It is possible to use very particularly the colloidal dispersions obtained by thermohydrolysis of an aqueous solution of a cerium IV salt such as a nitrate, in an acid medium in particular. Such a process is described in European patent applications EP-A-239477 or EP-A-208580. It is possible to start from previously purified dispersions or dispersions with a high pH value. These dispersions may have been obtained by treatment with a cationic and / or anionic resin as described in the aforementioned patent application EP-A-700870. For dispersions based on cerium and on the aforementioned element M, the method described in WO 01/55029 can be used.

For the preparation of a dispersion according to the second embodiment, the process is characterized in that, in a first step, a colloidal dispersion starting from a cerium compound or a cerium compound is added and at least one other element M mentioned above, the coupling compound comprising the chemical functions R's and Rc mentioned above; then, in a second step, the coloring compound comprising a chemical function R'c is added to the dispersion thus obtained. It is possible, during this second step, to heat the reaction medium to facilitate the formation of the covalent bond.

What has been said above for the starting dispersions also applies here for the process for preparing the dispersion according to this second mode.

It is possible at the end of the first step of the process to adjust the pH of the dispersion obtained to a value of at least 3, preferably at least 4. For this, it is possible in particular to use strongly anionic resins basic.

By way of example, mention may be made, for this type of resins, of those with a backbone of styrene-divinylbenzene copolymers. Use may more particularly be made of those having quaternary ammonium, OH "functional groups. Examples of anionic resins which can be used are Amberlite IRN 78® or Duolite A 101® resins.

The resin treatment is carried out in any suitable manner. The resins can be brought into direct contact with the colloidal dispersion. The quantity of anionic resin to be used is defined by the pH which it is desired to reach.

For the preparation of dispersions in the organic phase, a preparation process consists in starting from the organic phase in which it is desired to obtain the dispersion. For the dispersions according to the first embodiment, the particles of a cerium compound or of a cerium compound and of a compound of at least one other element M, the compound, are then brought into contact in the organic phase. amphiphilic aforementioned and a dye comprising a chemical function Rs. It is also possible to proceed in several stages. Thus, firstly, the organic phase and the particles of a cerium compound or of a cerium compound and of a compound of at least one other element M can be brought into contact. second time the dye preferably with stirring. Finally, in a last step, the amphiphilic agent is added. For the dispersions according to the second mode, the particles of a cerium compound or of a cerium compound and of a compound of at least one other element M are then brought into the organic phase, the above-mentioned amphiphilic compound , the coupling compound comprising a chemical function R's and a chemical function Rc and the coloring compound comprising a chemical function R'c. Again, it is possible to proceed in several stages. Thus, in a first step, the organic phase and the particles of a cerium compound or of a cerium compound and of a compound of at least one other element M can be brought into contact. second step the coupling compound, then the dye in a third step. Finally, in a last step, the amphiphilic agent is added.

Finally, for dispersions in which the continuous phase consists of a water / organic solvent mixture miscible with water or also an organic solvent miscible with water, the procedure is as indicated above, if necessary without using amphiphilic agent.

The present invention also covers the colored powders resulting from the drying of the dispersions which have just been described. This drying can be done by any known means, for example by passing through an oven or by atomization. It is preferably dried at a temperature which is at most 80 ° C. and more particularly at most 50 ° C.

The dispersions of the invention as well as the powders resulting from the drying of these can be used in particular for their anti-UV properties for example in the preparation of materials, in particular films, of polymers (of the acrylic or polycarbonate type for example) anti-UV and colored, possibly transparent, or in the preparation of cosmetic compositions in particular in the preparation of anti-UV creams or dyes. They can be used in coatings, for example in stain formulations.

Examples will now be given.

Example 1

This example relates to a colloidal dispersion of red CeO ₂ . 277 g of a precipitate of CeO ₂ dispersible at 62% in CeO ₂ , prepared according to Example 1 of patent application EP 208580 are dispersed in 1000 cc by demineralized water. The dispersion thus obtained has a CeO ₂ concentration of 1 M. It is left to stand at room temperature overnight (16 hours).

An aminocaproic acid solution is obtained by adding 39.3 g of 6-aminocaproic acid (i.e. 0.3 moles of amino acid, of molecular mass 131.2 g) in demineralized water, made up to 150 cm ³ . The solution of aminocaproic acid is then added to the colloidal dispersion of

CeO ₂ . The aminocaproic acid / CeO ₂ molar ratio is then equal to 0.3 and the cerium concentration is 0.87M in Ce. It is left to stand overnight at room temperature. The pH of the dispersion is pH 3.1.

To a 100cc aliquot of the colloidal dispersion of CeO ₂ thus treated, 5g of wet anionic resin IRN 78, Prolabo, previously conditioned, are added. Leave to stir for 10 minutes. The resin is separated from the colloidal dispersion by filtration. 5 g of wet anionic resin are added again. Leave to stir for 10 minutes. The resin is separated from the colloidal dispersion by filtration. The pH of the colloidal dispersion is 4. The assay of the colloidal dispersion by loss on ignition of an aliquot at 1000 ° C. gives 0.84M in CeO ₂ . To 20 cc of this colloidal dispersion thus prepared, 0.14 g of Procion Red MX 5B dye, Aldrich quality, is added, ie a dye / CeO ₂ mass ratio of 0.05.

The molar mass of the dye is equal to 615.34 g and the dye / Ce molar ratio is determined to be equal to 0.014. The dye contains sulfonate functions and reactive chloride functions. The dispersion retains perfect colloidal stability and develops a red coloration.

By ultracentrifugation at 50,000 rpm for 6 hours, a red pellet and a colorless supernatant are recovered, which clearly shows the existence of a strong bond between the dye and the mineral colloid. The assay carried out on the pellet after drying at 20 ° C. indicates a dye content of 2.5% and a CeO ₂ content of 77.5%. The dye / CeO ₂ mass ratio in the dried pellet is thus determined to be equal to 0.03.

Example 2

This example relates to a colloidal dispersion of blue CeO2. At 20 cc of the colloidal dispersion at pH 4, and 0.84 M in CeO ₂ prepared as described in Example 1, 0.14 g of Procion Blue PX 3R dye is added, which gives a dye / CeO ₂ mass ratio of 0.05 . The molar mass of the dye is equal to 881.5 g and the dye / Ce molar ratio is determined to be 0.01. The dye contains sulfonate functions and reactive chloride functions. The dispersion retains perfect colloidal stability and develops a blue color.

By ultracentrifugation at 50,000 rpm for 6 hours, a blue pellet and a colorless supernatant are recovered, which clearly shows the existence of a strong bond between the dye and the mineral colloid.

Example 3

This example concerns a colloidal dispersion of blue CeO ₂ . At 20 cc of the colloidal dispersion at pH 4, and 0.84 M in CeO ₂ prepared as described in Example 1, 0.14 g of Acid Blue Erioglaucine dye is added, which gives a dye / CeO ₂ mass ratio of 0.05.

The molar mass of the dye is equal to 792.86 g and the dye / Ce molar ratio is determined to be 0.01. The dye contains sulfonate functions without reactive chloride function. The dispersion retains perfect colloidal stability and develops a blue color.

By measurement in a tank with a width of 2mm, an anti UV cut at 440 nm is observed. By ultracentrifugation at 50,000 rpm for 6 hours, a blue pellet and a slightly colored supernatant are recovered. The assay carried out on the pellet after drying at 20 ° C. indicates a dye content of 2.0% and a CeO ₂ content of 76.5%. The dye / CeO ₂ mass ratio in the dried pellet is thus determined equal to 0.026, showing a bond between the dye and the surface of the nanometric CeO ₂ particles.

Example 4

This example concerns a colloidal dispersion of blue CeO ₂ .

520 g of Ce acetate (III) containing 49.5% CeO ₂ and 170 cm ³ of concentrated acetic acid are added to a beaker. It is then made up to 3000 ml with demineralized water. The whole is stirred until a solution clear to the eye is obtained.

A solid is precipitated using a continuous assembly comprising: a one liter reactor equipped with a paddle stirrer, set at 400 rpm with an initial base of water of 0.51 and a pH electrode;

-two feeding vials containing on the one hand, the solution of cerium salts described above and on the other hand, a 3 N ammonia solution The flow rate of the Ce acetate solution is fixed at 10 ml / min and the flow rate of the ammonia solution is 7.7 ml / min. The precipitation pH is 8.5.

The suspension obtained corresponding to the first 4 working volumes of the precipitation reactor is eliminated. The suspension formed after these first 4 volumes is collected and the precipitate separated from the mother liquors by centrifugation at 4500 rpm for 10 min. On an aliquot by calcination, a percentage of CeO ₂ of 27% is determined.

The precipitate is dispersed by adding demineralized water to obtain a dispersion at 0.3 M in Ce. The mixture is stirred for 15 min. Centrifuge again. Two successive operations are thus carried out.

The precipitate is redispersed at 0.25 M in Ce by demineralized water. 0.6 mole of aminocaproic acid per mole of Ce is added to the reaction medium and the mixture is left stirring in air for 48 hours. The dispersion obtained is colloidal, transparent to the eye and slightly brown in color. To 100 cm ³ of the dispersion thus obtained, we add 0.5 cm ^{3 of} ₂ O ₂

30% so as to transform Celll into CelV. Leave to stir. The dispersion is 52.2 g / l in CeO ₂ .

At 20 cm ³ of the colloidal dispersion thus obtained, 0.01 g of Procion Blue PX 3R dye is added, ie a dye / CeO ₂ mass ratio of 0.01.

The molar mass of the dye is equal to 881.5 g and the dye / Ce molar ratio is determined to be equal to 0.002.

The dye contains sulfonate functions and reactive chloride functions. The dispersion retains perfect colloidal stability and develops a blue color.

By measurement in a tank with a width of 2mm, there is an anti UV cut at 420 nm.

The Lab values according to the CIE 10 standard are L = 68.4 a = -23.54 b = -22.20. By ultracentrifugation at 50,000 rpm for 6 hours, a blue pellet and a colorless supernatant are recovered, showing a strong bond between the dye and the surface of the CeO ₂ nanoparticles.

Example 5 This example relates to a colloidal dispersion of red CeO ₂ without coupling agent. A precipitate of CeO ₂ , prepared according to Example 1, is dispersed in demineralized water, in order to obtain a dispersion of CeO ₂ . The dispersion is left to stand at room temperature overnight (16 hours).

This dispersion is washed twice by ultrafiltration (replacement of the solvent with demineralized water; the cutoff threshold of the ultrafiltration membrane is 3000Da). After washing, the dispersion has a concentration of 105.5 g / l and its pH is 2.0.

To 100 cc of this colloidal dispersion thus prepared, 0.105 g of Procion Red MX 5B dye, Aldrich product, is added, ie a dye / CeO ₂ mass ratio of 0.01.

The molar mass of the dye is equal to 615.34 g / mol and the dye / Ce molar ratio is determined to be equal to 0.003.

The dye contains sulfonate functions and reactive chloride functions. The dispersion retains perfect colloidal stability and develops a red coloration.

By ultracentrifugation at 50,000 rpm for 6 hours, a red pellet and a colorless supernatant are recovered, which clearly shows the existence of a strong bond between the dye and the mineral colloidal particle.

Example 6

This example relates to a colloidal dispersion of red CeO ₂ without coupling agent.

At 20 cc of a colloidal dispersion prepared as described in Example 4, with a concentration of 89 g / l of CeO ₂ and at pH 4.2, 0.086 g of Procion Red MX 5B dye, Aldrich product, is added, which gives a ratio mass dye / CeO ₂ of 0.05.

The molar mass of the dye is equal to 615.34 g / mol and the dye / Ce molar ratio is determined to be equal to 0.015.

By ultracentrifugation at 50,000 rpm for 6 hours, a red pellet and a slightly colored supernatant are recovered, which shows the existence of a bond between the dye and the mineral colloid.

Claims

1- Colloidal dispersion in a continuous phase of particles of a cerium compound or a cerium compound and of a compound of at least one other element M chosen from titanium, zirconium, aluminum and earths rare other than cerium, characterized in that it comprises a dye bound to said particles via a chemical function Rs of said dye which is capable of creating between the particles and the dye a bond by complexation, by adsorption or electrostatic type.

2- Colloidal dispersion in a continuous phase of particles of a cerium compound or a cerium compound and of a compound of at least one other element M chosen from titanium, zirconium, aluminum and earths rare other than cerium, characterized in that it comprises: - a coupling agent linked to said particles by means of a chemical function R's of said agent which is capable of creating between the particles and the agent a bond by complexation , by adsorption, of the electrostatic or covalent type; - a dye linked to said coupling agent by a covalent bond.

3- Dispersion according to claim 2, characterized in that the dye further comprises a chemical function Rs which is capable of creating between the particles and the dye a bond by complexation, by adsorption or of the electrostatic type.

4- Dispersion according to one of the preceding claims, characterized in that the abovementioned chemical functions Rs and R's are carboxyl, carboxylate, sulfonate or sulfonic acid, sulfosuccinate, R's functions which may also be a phosphonate or phosphate function.

5- Dispersion according to one of the preceding claims, characterized in that the coupling agent is the remainder of a coupling compound comprising a chemical function Rc capable of reacting to form a covalent bond, this coupling compound being able moreover include a chemical function R's capable of reacting to form a bond by complexation, by adsorption, of the electrostatic or covalent type. 6- Dispersion according to one of claims 2 to 5, characterized in that the dye is the remainder of a dye compound comprising a chemical function R'c capable of reacting to form a covalent bond.

7- Dispersion according to claim 5 or 6, characterized in that the chemical functions Rc and R'c above are an amino group, aldehyde or a halogen.

8- Dispersion according to claim 5, characterized in that the above-mentioned coupling compound corresponds to the formula:

in which Ri is an alkyl group comprising from 1 to 12 carbon atoms, Zi is a group - CO ₂ H, carboxylate - CO ₂ M 'or - -SO ₃ M', M 'denoting a metal, in particular an alkali metal, Z ₁ can also be a phosphate or phosphonate group, Z ₂ denotes a halogen or a group - NHR ₂ , or - NR ₃ R _2l or - NH ₄ ⁺ , R ₂ and R ₃ , identical or different, denoting a hydrogen or a alkyl group comprising from 1 to 8 carbon atoms.

9. Dispersion according to claim 8, characterized in that the coupling compound is an amino acid.

10- Dispersion according to claim 9, characterized in that the amino acid is an aliphatic acid, more particularly a C ₄ -C ₁₀ acid.

11- Dispersion according to one of the preceding claims, characterized in that the continuous phase is water.

12- Dispersion according to one of claims 1 to 10, characterized in that the continuous phase is an organic phase and in that it comprises at least one amphiphilic compound chosen from polyoxyethylenated alkyl ethers of carboxylic acids, alkyl ethers polyoxyethylenated phosphates, dialkyl sulfosuccinates and quaternary ammonium compounds.

13- Dispersion according to one of claims 1 to 12, characterized in that the continuous phase is constituted by a water / organic solvent mixture miscible with water or by an organic solvent miscible with water. 14- A method of preparing an aqueous colloidal dispersion according to one of claims 1, 3 to 11 and 13, characterized in that added to a starting colloidal dispersion of a cerium compound or a compound of cerium and at least one other element M mentioned above, a dye comprising a chemical function Rs which is capable of creating between the particles and the dye a bond by complexation, by adsorption or of the electrostatic type.

15- A method of preparing an aqueous colloidal dispersion according to one of claims 2 to 11 and 13, characterized in that one adds, in a first step, to a colloidal dispersion starting from a compound of cerium or d 'a compound of cerium and of at least one other element M mentioned above, a coupling compound comprising a chemical function R's which is capable of creating with the particles a bond by complexation, by adsorption, of the electrostatic or covalent type; and a chemical function Rc capable of reacting to form a covalent bond; then, in a second step, a coloring compound comprising a chemical function R'c capable of reacting to form a covalent bond is added to the dispersion thus obtained.

16- Preparation process according to claim 15, characterized in that after the first step, the pH of the dispersion obtained is adjusted to a value of at least 3, preferably at least 4.

17- Process for the preparation of a dispersion according to claim 12 in combination with one of claims 1 and 3 to 10, characterized in that the particles of a cerium compound or a composed of cerium and a compound of at least one other element M chosen from titanium, zirconium, aluminum and rare earths other than cerium; the above-mentioned amphiphilic compound and a dye comprising a chemical function Rs which is capable of creating between the particles and the dye a bond by complexation, by adsorption or of the electrostatic type.

18- A process for preparing a dispersion according to claim 12 in combination with one of claims 2 and 3 to 10, characterized in that the particles in the organic phase are present of a cerium compound or a composed of cerium and a compound of at least one other element M chosen from titanium, zirconium, aluminum and rare earths other than cerium, the above-mentioned amphiphilic compound; a coupling compound comprising a chemical function R's which is capable of creating with the particles a bond by complexation, by adsorption, of the electrostatic or covalent type and a chemical function Rc capable of reacting to form a covalent bond and a coloring compound comprising a function chemical R'c capable of reacting to form a covalent bond.

19- Powder, characterized in that it is obtained by drying a dispersion according to one of claims 1 to 13.

20- Use of a dispersion of the type according to one of claims 1 to 13 or of a powder according to claim 19, in the preparation of polymer materials, in cosmetic compositions, in coatings, more particularly in formulations of isures.