Treating substrates comprises treating with dispersion of photocatalytic particles and then with siliconized compound selected from siliconates and polyorganosiloxanes

PROCESS FOR TREATMENT OF A SUBSTRATE WITH PHOTOCATALYTIC PARTICLES

The present invention relates to a process for treating substrates with titanium dioxide particles.

It is known that titanium dioxide allows, by virtue of its photocatalytic activity, the degradation of organic or bioorganic molecules.

If this photocatalytic titanium dioxide is deposited on a support, the surface of this support becomes oxidizing and the soiling - in particular organic - which is deposited thereon is destroyed by photooxidation. The surface is said to be self-cleaning.

The deposition of titanium dioxide on the surface of the substrate can be carried out from dispersions of titanium dioxide particles. Preferably, dispersions of particles having a small size, in particular nanoparticulate, are used so as to obtain translucent surfaces, unlike micrometric titanium dioxide which gives white surfaces.

The treated surfaces can be glass, plastics, construction materials (mortars, concrete, terracotta), ceramics, stones, paper or wood.

The deposit of titanium dioxide on these supports must strongly adhere to the support so that the treated surfaces can be put in place and so that they retain their self-cleaning properties over time. It is also necessary that the binder which allows the particles to adhere to the support is not sensitive to the photocatalysis of the titanium dioxide particles.

For this purpose, several methods have been implemented proposing different types of binders making it possible to bond the particles to the substrate.

A first method consists in depositing dispersions of titanium dioxide particles containing the precursor of a binder on the hot substrate. For example, it has been proposed to use dispersions of titanium dioxide particles and organometallic binders such as titanates or silicates. The particles are then caught in a film of silica or titanium dioxide (this principle is described for example in WO 97/10185). This mineral binder has the advantage of not being photodegradable.

A second method consists in depositing dispersions of titanium dioxide particles containing an organic binder on the cold substrate. One problem is that this binder must not degrade under the effect of the photocatalytic properties of the titanium dioxide particles. For this, it has been proposed, for example, to choose the binder from silicones.

However, although the silicone binders offered do not degrade on contact with the photocatalytic particles, it is observed that they do not always lead to a homogeneous, hard and adherent coating: very often, the coatings obtained can be removed by simple friction with the finger.

An aim of the present invention is therefore to provide a process for depositing dispersions of titanium dioxide particles in order to cold form photocatalytic coatings on the surface of the substrate.

Another aim of the present invention is to provide such a process leading to homogeneous, hard and adherent coatings.

For these purposes, the invention relates to a method for treating the surface of a substrate in which the following steps are implemented:

1. the substrate is treated with a dispersion of photocatalytic particles, then

2. the substrate is treated with at least one silicone compound chosen from:

o (a) the siliconates of formula (I);

R- Si (OM)_m(OH)₃._m (I) in which:

- R is a hydrocarbon residue of 1 to 18 carbon atoms, optionally substituted by a halogen atom, an amino, ether, ester, epoxy, mercapto.cyano or (poly) glycol group,

- m is a whole or fractional number between 0.1 and 3,

- M is an alkali metal, an ammonium group or a phosphonium group, and / or the condensation products of said siliconates, => (b) polyorganosiloxanes • either of average formula (II): M_atDpQ_oh(O_1/2Rⁱ)_e, in which :

♦ M = R ^ SiO ^

D ⁼ R ** 2SiO2 / 2

Q - SÎO4 / 2 with R, identical or different, representing either a linear or branched alkyl radical having from 1 to 8 carbon atoms, or a substituted or unsubstituted aryl group having from 6 to 12 carbon atoms, or an aralkyl group, alkaryl, aryloxyalkyl or alkoxyaryl in which the aryl group comprises from 6 to 12 carbon atoms which can optionally be substituted by at least one alkyl or alkoxy group, linear or branched, having from 1 to 4 carbon atoms, and in which the alkyl or alkoxy group has 1 to 4 carbon atoms and is linear or branched, ♦ α, β and δ respectively represent the mole fractions of the silicon atoms of the units M, D and Q, with α + β + δ = 1, and:

a <0.10, preferably a <0.010, β <0.85, δ> 0.10, ♦ R ', identical or different, represent an alkyl group having from 1 to 4 carbon atoms, ♦ ε representing the number means of O patterns_1/2Rⁱ per silicon atom is between 0.1 and 1.5, • either of average formula (III): M_atDpT_y(O_1/2R ')_e, in which :

♦ M, D, R 'and ε have the meaning above, T = R ^ SiC ^, with R^ij with the same meaning as above, ♦ α, β and γ represent respectively the molar fractions of the silicon atoms of the units M, D and T, with α + β + γ = 1, and:

a <0.20, preferably a <0.010, β <0.60, γ> 0.30, (c) a silane or a silane oligomer of formula (IV):

(R ') u SiX (₄-u) ('V) where:

- the molecular weight of the silane is less than 700 g,

- R ', identical or different, are monovalent organic radicals, in particular linear or branched alkyl or alkenyl in C-ι to C₃₀ optionally substituted by a halogen group (F, Cl, Br) an epoxidized group, an amino group,

- u is equal to 0, 1 or 2,

- X, identical or different, are condensable and / or hydrolyzable organic groups and represent:

. an OH group,. an alkoxy or alkenyloxy group containing from 1 to 10 carbon atoms (methoxy, ethoxy, n-propoxy, isopropoxy),. an aryloxy group containing from 6 to 13 carbon atoms,. a ketiminoxy group containing from 1 to 8 carbon atoms,. an amino-functional or amido-functional group containing from 1 to 6 carbon atoms, linked to silicon by an Si-N bond.

The invention therefore consists in successively treating the substrate first of all with a dispersion of photocatalytic particles, then then with at least one silicone compound.

The dispersion of particles and the silicone compound are generally in liquid form. They can be deposited on the substrate by any conventional deposition method such as a brush, roller, gun or spray.

After application of each of the two treatments, the substrate is generally allowed to dry at room temperature.

The substrate can be of various types: it can be, for example, glass, polymers (plastics), building materials such as mortars, concrete, terracotta, ceramics, stones, wood, metals , of paper.

According to the invention, the photocatalytic particles of the dispersion to be deposited on the substrate are preferably titanium dioxide particles having a size of at most 100 nm, in particular between 10 and 50 nm. The diameters are measured by transmission electron microscopy (TEM).

The nature of the crystalline phase is preferably predominantly the anatase crystalline form. Mainly means that the level of anatase in the titanium dioxide particles is greater than 50% by mass. Preferably, the particles have an anatase level greater than 80%. The degree of crystallization and the nature of the crystalline phase are measured by X-ray diffraction.

It is preferable to use monodisperse titanium dioxide particles in order to obtain more transparent coatings. The term “monodisperse” means particles having a dispersion index of at most 0.5, preferably at most 0.3, the dispersion index being given by the following formula:

⁰84'⁰16 ²⁰5O in which:

- 0₈₄ is the diameter of the particles for which 84% by weight of the particles have a diameter less than 0₈₄,

- 0₁₆ is the diameter of the particles for which 16% by weight of the particles have a diameter less than 0₁₆,

- 0_5O is the average particle diameter.

The diameters useful for determining the dispersion index are measured by centrifugal sedimentation of the particles of the dispersion, followed by X-rays, using a Brookhaven type XDC apparatus.

The monodisperse particles of the dispersion are preferably obtained from a so-called solution or wet preparation process (thermolysis, thermohydrolysis or precipitation of a titanium salt) as opposed to oxidation or high temperature pyrolysis processes. a titanium salt. They may for example be titanium dioxide particles obtained by the process described in application EP-A-0 335 773.

It may in particular be the preparation process which consists in hydrolyzing at least one titanium compound A in the presence of at least one compound B chosen from:

(i) acids which have:

- either a carboxyl group and at least two hydroxyl and / or amine groups,

- either at least two carboxyl groups and at least one hydroxyl and / or amine group, (ii) organic phosphoric acids of the following formulas:

HO OR² O OH \ Il I II /

P - (C)_not - P / I \

HO R¹ OH

HO O OH O OH \ Il I II /

P - C _ P / I \

HO R³ OH

<td colspan="2"></td><td>O II</td><td>OH Z</td>

<td>HO O</td><td>CH₂ _</td><td>P</td><td>- OH</td>

<td>\ He</td><td>Z</td><td></td><td></td>

<td>P_CH₂_ [N- (CH₂)_m]_p-</td><td>NOT</td><td></td><td></td>

<td>/ I</td><td> \</td><td></td><td></td>

<td>HO CH₂</td><td>ch₂_</td><td>P.</td><td>_ OH</td>

<td>I</td><td></td><td>He</td><td> \</td>

<td>O = P- OH I</td><td></td><td>O</td><td>OH</td>

<td>1 OH</td><td></td><td></td><td></td>

in which, n and m are integers between 1 and 6, p is an integer between 0 and 5, R¹, R², R³ identical or different representing a hydroxyl, amino, aralkyl, aryl, alkyl or hydrogen group, (iii) compounds capable of liberating sulfate ions in an acidic medium, (iv) salts of the acids described above, and in the presence seeds of anatase titanium dioxide having a size of at most 5 nm and in a weight ratio expressed as TiO₂ present in the seeds / titanium present before introduction of the seeds into the hydrolysis medium, expressed as TiO₂, between 0.01% and 3%.

This process for preparing the particles therefore comprises several steps and, firstly, a step for preparing the starting solution comprising a titanium compound A, a compound B as defined above and seeds of titanium dioxide.

This starting solution, intended to be hydrolyzed, is preferably completely aqueous; optionally, another solvent can be added, for example an alcohol, provided that the titanium compound A and the compound B used are then substantially soluble in this mixture.

As regards the titanium compound A, a compound chosen from halides, oxyhalides, titanium alkoxides, sulphates and more particularly synthetic sulphates is generally used.

The term “synthetic sulphates” is understood to mean solutions of titanyl sulphates produced by ion exchange from very pure titanium chloride solutions or by reaction of sulfuric acid with a titanium alkoxide.

Preferably, the operation is carried out with titanium compounds of the titanium halide or oxyhalide type. The titanium halides or oxyhalides more particularly used in the present invention are the fluorides, chlorides, bromides and iodides (respectively oxyfluorides, oxychlorides, oxybromides and oxyiodides) of titanium.

According to a particularly preferred embodiment, the titanium compound is titanium oxychloride TiOCI₂.

The amount of titanium compound A present in the solution to be hydrolyzed is not critical.

The initial solution also contains at least one compound B as defined above. By way of nonlimiting examples of compounds B coming within the scope of the present invention, there may be mentioned in particular:

- hydroxypolycarboxylic acids, and more particularly hydroxydi- or hydroxytricarboxylic acids such as citric acid, maleic acid and tartaric acid.

(polyhydroxy) monocarboxylic acids, such as, for example, glucoheptonic acid and gluconic acid,

- poly (hydroxycarboxylic) acids, such as, for example, tartaric acid,

- mono dicarboxylic acids and their corresponding amides, such as for example aspartic acid, asparagine and glutamic acid,

- monocarboxylic amino acids, hydroxylated or not, such as, for example, lysine, serine and threonine, methylene aminotriphosphonate, methylene ethylenediaminotetraphosphonate, methylene triethylenetraaminohexaphosphonate, tetraethylenhexaphosphene, ethylene pentaaminoheptaphosphene, ethylene pentaphosphonate

- methylene diphosphonate; 1.1 'ethylene; 1,2 ethylene; 1.1 'propylene;

1.3 propylene; 1.6 hexamethylene; 2,4 dihydroxypentamethylene - 2,4 diphosphonate; 2,5 dihydroxyhexamethylene - 2,5 disphosphonate; ie 2,3 dihydroxybutylene - 2,3 diphosphonate; 1 hydroxybenzyl - 1,1 'diphosphonate; ie 1 aminoethylene 1-1 'diphosphonate; hydroxymethylene diphosphonate; 1 hydroxyethylene 1,1 'diphosphonate; 1-hydroxypropylene 1-1 'diphosphonate; 1-hydroxy butylene 1-1 'diphosphonate; 1 hydroxyhexamethylene - 1,1 'diphosphonate.

As already indicated, it is also possible to use as compound B all the salts of the aforementioned acids. In particular, these salts are either alkali metal salts, and more particularly sodium salts, or ammonium salts.

These compounds can also be chosen from sulfuric acid and ammonium or potassium sulphates.

Preferably, the compounds B as defined above are hydrocarbon compounds of the aliphatic type. In this case, the length of the main hydrocarbon chain preferably does not exceed 15 carbon atoms, and more preferably 10 carbon atoms.

The amount of compound B is not critical. In general, the molar concentration of compound B relative to that of titanium compound A is between 0.2 and 10% and preferably between 1 and 5%.

Finally, the starting solution comprises seeds of titanium dioxide used in a specific manner.

First of all, the titanium dioxide seeds used must have a size of at most 5 nm, measured by X-ray diffraction. Preferably, titanium dioxide seeds having a size between 3 and 5 nm are used.

Then, the weight ratio of the titanium dioxide present in the seeds to the titanium present in the hydrolysis medium before introduction of the seeds (that is to say provided by the titanium compound A), and expressed in TÎO₂, is between 0.01 and 3%. This ratio can preferably be between 0.05 and 1.5%. The combination of these two conditions on the seeds (size and weight ratio) associated with the process as described above makes it possible to precisely control the final size of the titanium dioxide particles by associating a particle size with a number of seeds. It is thus possible to obtain particles whose size varies between 5 and 100 nm.

Seeds of titanium dioxide in anatase form are used so as to induce precipitation of titanium dioxide in anatase form. Generally, due to their small size, these germs tend to be in the form of poorly crystallized anatase. The seeds are usually in the form of an aqueous suspension consisting of titanium dioxide. They can be obtained in a known manner by a process for neutralizing a titanium salt with a base.

The next step consists in carrying out the hydrolysis of this starting solution by any means known to those skilled in the art and in general by heating. In the latter case, the hydrolysis can preferably be carried out at a temperature greater than or equal to 70 ° C. It is also possible to work initially at a temperature below the boiling point of the medium and then to maintain the hydrolysis medium in a level stage at the boiling point.

Once the hydrolysis has been carried out, the titanium dioxide particles obtained are recovered by separating the precipitated solid from the mother liquors. Then, they are redispersed in an aqueous liquid medium so as to obtain a dispersion of titanium dioxide. This liquid medium can be acidic or basic.

It has been observed that the titanium dioxide particles resulting from a so-called solution or wet preparation process, and in particular resulting from the process described above with hydrolysis at a temperature of approximately 100 ° C., present, by their porosity, a lower refractive index than titanium dioxide particles from other processes. This property is of great interest when the particles are used to prepare a coating on a glass substrate, since the coating obtained also has a low refractive index. This optical advantage is important because a layer with a high index of titanium dioxide leads to an increase in the light reflection of the carrier lens, and therefore to a reduction in its light transmission. However, for certain applications, in particular in the field of glazing fitted to vehicles, it is essential to have high levels of light transmission (for a windshield, a minimum light transmission of 75% is necessary). Preferably, the particles of the dispersion have a BET specific surface area of ​​at least 70 m²/ g.

By BET specific surface is meant the specific surface determined by nitrogen adsorption in accordance with the ASTMD 3663-78 standard established from the BRUNAUER - EMMETT - TELLER method described in the periodical The Journal of the American Society, 60, 309 ( 1938). To measure the specific surface area of ​​the particles according to the invention, when they are in the form of a dispersion, it is essential to follow the measurement protocol which consists in removing the liquid phase from the dispersion and then in drying the particles under vacuum at a temperature. temperature of 150 ° C for at least 4 hours.

Preferably, the particles of the dispersion also have a density of the order of 2.4. By order is meant that the density is 2.4 ± 0.2. Such a density value is low compared to the conventional density of anatase titanium dioxide which is 3.8. This density is evaluated by measuring the pore volumes.

These specific surface and density characteristics can be obtained for the titanium dioxide particles resulting from a so-called solution or wet preparation process, and in particular resulting from the process described above with hydrolysis at a temperature of approximately 100. ° C.

The titanium dioxide particles can also be obtained commercially. They can come in various forms.

They may first of all be aqueous dispersions of titanium dioxide particles, such as those sold by RHODIA CHIMIE under the name S5300 or dispersions obtained according to the process described in patent EP-A-0 335 773 as described. previously. Preferably, basic aqueous dispersions are used, since it has been observed that the latter lead to dispersions giving more transparent coatings than the acidic aqueous dispersions. In the case of deposition on glass, this difference can be attenuated if the glass is activated with NaOH before the deposition.

They can also be organic dispersions of titanium dioxide particles. These can be prepared from aqueous dispersions of titanium dioxide particles, the phase transfer being, for example, carried out according to one of the following methods:

- washing with acetone or with the desired solvent by centrifugation and redispersion in the organic solvent,

- azeotropic distillation of the water / solvent mixture if the water and the solvent are immiscible and form an azeotrope,

- evaporation of water using a rotary evaporator if the solvent is miscible with water and boils at a temperature higher than that of water

- mixing of an aqueous dispersion with an organic medium comprising a cationic transfer agent, if the particles are negatively charged, the latter possibly being chosen in particular from quaternary amines or quaternary ammonium salts, or a medium comprising an agent of anionic transfer, if the particles are positively charged (this process is more particularly described in GB-A-988,330).

It is also possible to use titanium dioxide powders; these must be suspended for the purposes of the process according to the present invention. Such powders are commercially available, mention may be made of the G5 or DT51D powders sold by RHODIA CHIMIE. Powders can also be obtained by atomization of an aqueous dispersion as described above. Preferably, the particles already in the form of dispersions are used, in particular when it is desired to obtain a transparent surface treatment, the powders generally leading to less transparent coatings.

According to the process of the invention, the silicone compound is deposited in a second step. The latter can be of varied nature.

According to a first variant, it may be a siliconate of formula (I) and / or the condensation products thereof. Siliconates are salts of siliconic acid or its derivatives.

Generally, in formula (I), R is a hydrocarbon residue of 1 to 10 carbon atoms and more particularly of 1 to 6 atoms. Preferably, R is:

- an alkyl radical, for example: methyl, ethyl, propyl, butyl, isobutyl,

- an alkenyl radical, for example vinyl,

- an aryl radical, for example phenyl or naphthyl,

- an arylalkyl radical, for example, benzyl or phenylethyl,

- an alkylaryl radical such as, for example, tolyl, xyxyl, or

- an araryl radical such as biphenylyl.

For the metal M of formula (I), there may be mentioned more particularly sodium or potassium as well as the N groups⁺R '⁴, P⁺R '⁴ in which the groups R 'are identical or different and represent hydrocarbon residues of 1 to 6 carbon atoms. According to the invention, use is more particularly made of alkali metal siliconates. It is also possible to use alkaline earth siliconates.

Preferably, the siliconates of formula (I) are used for which:

- R is a vinyl or phenyl radical, and more particularly alkali metal siliconates of this type,

- alkaline alkylsiliconates such as sodium or potassium methylsiliconates.

These alkali metal or alkaline earth siliconates can be prepared, for example, by hydrolysis of the corresponding silanes having three hydrolyzable groups (such as halogen atoms, alkoxy radicals) followed by dissolving the product obtained in a solution of an inorganic base. strong in proportions such that there is at least one base equivalent per silicon atom (see for example US A 2,441,422 and US A 2,441,423).

These products are generally available commercially. As example of commercially available siliconates of this type, mention may in particular be made of RHOXIMAT® Siliconate 51 T, sold by RHODIA CHIMIE, which is a potassium methylsiliconate.

According to this first variant, they may also be derivatives of the siliconate. The term “derived products” is understood here to mean the condensation products of the products corresponding in particular to formula (I) described above or those resulting from the at least partial polymerization into silicone compounds or polymers. It is known, for example, that alkali metal alkylsiliconates can be converted into polyalkylsiloxanes, in particular by the action of carbon dioxide or other acidifying agent.

The siliconates (a) are usually used in the form of aqueous solutions.

According to a second variant of the process, the silicone compounds is a polyorganosiloxane (b) either of formula (II) or of formula (III).

Preferably, the polyorganosiloxane (b) is of formula (II) or (III) and R ′ is an ethyl or methyl group. On average, the polyorganosiloxane can also have silanol ends (R ′ = H), said ends not representing more than 20% of the totality of the ends.

According to a first embodiment, a polyorganosiloxane of formula (III) is used in which:

- for each unit M = R '^ SiO ·) ^ · the three substituents R are methyl,

- for each pattern T = R^notSiO3_/2, R is methyl,

- for each unit D = R '^ SiC ^, one substituent R is a methyl and the other substituent R^H is an octyl,

- a is at most 0.05,

- β is at most 0.10,

- γ is at least 0.70,

- ε is between 0.2 and 1.

According to a second embodiment, a polyorganosiloxane of formula (III) is used in which:

- for each unit M = R '^ SIO · ^, the three substituents R are methyl,

- for each unit T = Ri'SiOg ^, R is a methyl,

- for each unit D = R '^ SiC ^ the two substituents R are methyl,

- a is at most 0.05,

- β is at most 0.30,

-γ is at least 0.70,

- ε is between 0.2 and 1.

According to a third embodiment, a polyorganosiloxane of formula (III) in which:

- for each unit M = R '^ SiO ^, the three substituents R are methyl,

- for each pattern T = R^liSiO₃/ 2, R^not is a propyi,

- for each unit D = R '^ SiC ^. the two R substituents^NOT are methyl,

- a is at most 0.05,

- β is at most 0.50,

- γ is at least 0.40,

- ε is between 0.3 and 0.6.

This latter mode is preferred when the substrate to be treated is alkaline (from the point of view of the pH generated in the presence of water). This is the case of construction materials (for example mortars, concretes) obtained by the mixture of hydraulic binder (cement), inert material (aggregates), water and possibly admixture.

The polyorganosiloxane (b) can be in solution in a liquid phase. This liquid phase is preferably an organic solvent, which can be chosen from the solvents for silicone polymers, such as, for example, D4 ​​(octamethylcyclotetrasiloxane) or other volatile siloxanes, white spirit, C ^ Cg alcohols, aliphatic hydrocarbons. or aromatics such as cyclohexane or alkanes. The choice of the liquid phase is made according to its compatibility with the polyorganosiloxane. It is thus possible to play on the transparency of the final coating.

In this case, a crosslinking catalyst is preferably added to the polyorganosiloxane (b). This crosslinking catalyst can be chosen from organic titanium or tin compounds, in particular alkyl titanates and dialkyltin dicarboxylate.

According to a preferred implementation of the invention, the polyorganosiloxane (b) is in the form of an emulsion in aqueous phase. This aqueous emulsion preferably comprises:

• a polyorganosiloxane of formula (II) or (III) • the product (Z) of the reaction between:

- (Za) at least ammonia and / or an aromatic and / or aliphatic polyfunctional amine soluble in water containing from 2 to 25 carbon atoms,

- (Zb) at least one carboxylic acid or anhydride containing from 3 to 22 atoms, • and at least one surfactant (Y) chosen from the following classes:

(Ya) nonionic surfactants selected from;

(i) polyoxyalkylenated alkylphenols in which the alkyl substituent is C₆-VS₁₂and containing from 5 to 25 oxyalkylene units;

(ii) aliphatic alcohols at C_g-VS₂₂ polyoxyalkylenates containing from 1 to 25 oxyalkylene units;

(iii) alkoxylated terpene hydrocarbons such as ethoxylated and / or propoxylated α- or β-pinenes, containing from 1 to 30 oxyethylene and / or oxypropylene units;

(iv) the products resulting from the condensation of ethylene oxide or of propylene oxide with propylene glycol, ethylene glycol, of molecular mass by weight of the order of 2000 to 10,000;

(v) products resulting from the condensation of ethylene oxide or propylene oxide with ethylenediamine;

(vi) ethoxylated and / or propoxylated fatty acids at C_g-VS_1g containing from 5 to 25 ethoxylated and / or propoxylated units;

(vii) ethoxylated fatty amides containing from 5 to 30 units;

(viii) ethoxylated amines containing from 5 to 30 ethoxylated units;

(ix) - alkoxylated amidoamines containing from 1 to 50, preferably from 1 to 25, very particularly from 2 to 20 oxyalkylene units, preferably oxyethylene;

(x) ethoxylated tristyrylphenols;

(Yb) anionic surfactants chosen from:

(i) alkyl ester sulfonates of formula R-CH (SO₃M) -COOR ', where R represents an alkyl radical in C₈-₂₀. preferably in C₁₀-VS₁₆, R 'represents an alkyl radical in C ^ Cg, preferably of C., - C₃ and M is an alkaline cation (sodium, potassium, lithium), a substituted or unsubstituted ammonium (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) or a derivative of an alkanolamine (monoethanolamine, diethanolamine, triethanolamine). Mention may very particularly be made of methyl ester sulfonates in which the radical R is at C₁₄-VS₁₆ ;

(ii) alkylsulphates of formula ROSO₃M, where R represents an alkyl or hydroxyalkyl radical in C₅-VS₂₄, preferably in Ο_1θ-Ο_1β, M represents a hydrogen atom or is of the same definition as in paragraph Ya (i), (iii) the ethoxylenated (OE) and / or propoxylenated (OP) derivatives of the alkylsulfates defined in paragraph e (ii), presenting in average from 0.5 to 30 units, preferably from 0.5 to 10 EO and / or PO units;

(iv) sulfated alkylamides of formula RCONHR'OSO₃M where R represents an alkyl radical in C₂-VS₂₂, preferably Cg-C₂₀, R 'an alkyl radical in C₂-VS₃, M representing a radical as defined in paragraph Ya (i) or a hydrogen atom, (v) ethoxylenated (OE) and / or propoxylenated (OP) derivatives of sulfated alkylamides defined in paragraph e (iv), exhibiting in average from 0.5 to 60 EO and / or OP units;

(vi) salts of saturated or unsaturated fatty acids in C₈-VS₂₄, preferably in Οι₄-Ο_2θ, alkylbenzenesulfonates in C_g-VS₂₀, primary or secondary C alkyl sulfonates₈-VS₂₂, alkylglycerol sulfonates, sulfonated polycarboxylic acids described in GB-A-1 082 179, paraffin sulfonates, N-acyl N-alkyltaurates, alkylphosphates, isethionates, alkylsuccinamates, alkylsulfosuccinates, monoesters or diesters of sulfosuccinates, N-acyl sarcosinates, alkyl glycoside sulfates, polyethoxycarboxylates; the cation being an alkali metal (sodium, potassium, lithium), a substituted or unsubstituted ammonium residue (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) or derivative of an alkanolamine (monoethanolamine, diethanolamine, triethanolamine);

(Yc) amphoteric and zwitterionic surfactants chosen from:

(i) alkyldimethylbetaines, alkylamidopropyldimethylbetaines, alkyltrimethylsulfobetaines, condensation products of fatty acids and protein hydrolysates, (ii) alkylamphoacetates or alkylamphodiacetates in which the alkyl group contains from 6 to 20 carbon atoms, (iii) phosphoaminolipids such as lecithin.

As examples of commercial products of type surfactants (Yb), mention will be made of the SIPON® LCS 95 or 98 products from the company Sidobre Sinnova (sodium laurisulphate) and NANSA® 1169A from the company Albright and Wilson ( sodium dodecylbenzenesulfonate).

As examples of commercial products of surfactants (Yc), mention will be made of the products MIRANOL® C32, MIRANOL® C2M from RHODIA CHIMIE (cocoamphoacetate), the products ALKATERIC® 2CIB, CB, PB.CAB and l_AB from RHODIA CHIMIE .

The amines (Za) are ammonia and / or primary, secondary or tertiary amines, optionally substituted, for example by one or more OH groups, or amines in the form of amides or amino acids.

Particularly preferably, they are alcohol amines and in particular amines containing an alkyl group (s) having from 1 to 5 carbon atoms and substituted by at least one OH, preferably from 1 to 3.. can cite in particular:

- amino methylpropanol, for example: 2-amino-2-methylpropan-1-ol;

- amino ethyl propanediol, for example: 2-amino-2-ethylpropan-1,3-diol, which is the preferred;

- triethanolamine.

They may also be diamines, such as hydrazine and hexamethylenediamine, cyclic amines such as morpholine and pyridine, aromatic and aliphatic amino acids such as 3-methyl-4-aminobenzoic acid, or else d 'amides of formula (V):

R⁷-CNR⁸R⁹

II o

in which R⁷, R⁸ and R⁹ can represent hydrogen or alkyl groups having 1 to 5 carbon atoms, such as formamide, acetamide, Nethylacetamide and N, N-dimethylbutyramide.

The carboxylic acid (Zb) is preferably a saturated or unsaturated, linear or branched, CC, preferably C -C „„ fatty acid, optionally substituted, for example by an OH group, such as in particular oleic acid, acid. isostearic, stearic acid, ricinoleic acid and tall oil fatty acid.

The aqueous polyorganosiloxane emulsion (b) can optionally comprise at least one crosslinking agent which is a water-soluble metal. Preferred crosslinking agents contain zinc, aluminum, titanium, copper, chromium, iron, zirconium and / or lead. The crosslinking agents can be a salt or a complex of such a metal or of such metals. The salts can be acidic, basic or neutral. Suitable salts include halides, hydroxides, carbonates, nitrates, nitrites, sulfates, phosphates. Particularly preferred crosslinking agents in the context of the present invention are zirconium complexes, for example those described in patent application GB-A-1 002 103, which are salts of the zirconyl radical with at least two monocarboxylic acids, one acidic group having 1 to 4 carbon atoms, the other having more than 4 carbon atoms, and which can be carried out by refluxing the carboxylic acid of 1 to 4 carbon atoms with a paste of zirconyl carbonate, then adding the carboxylic acid having more than 4 carbon atoms. Water soluble inorganic metal compounds can also be used. Zirconium ammonium carbonate is particularly preferred.

The polyorganosiloxane emulsion (b) can also include a metal curing compound. These compounds are essentially the salts of carboxylic acids, the titanates of alkanolamines, the halides of metals chosen from lead, zinc, zirconium, titanium, iron, tin, calcium and manganese. Catalytic compounds based on tin, generally an organotin salt (eg tin bischelates, diorganotin dicarboxylates) are suitable.

Preferably, the emulsion comprises a polyorganosiloxane of formula (III) in which:

- for each pattern M = R '^ SiO ^ - Rest ^a methyl,

- for each unit T = Ri'SiC ^, R is a propyl,

- for each motif D = R^H2SiO_2/2, the two substituents R^H are methyl,

- a is at most 0.05,

- β is at most 0.50,

- γ is at least 0.40,

- ε is between 0.3 and 0.6, which corresponds to the third mode defined above.

The aqueous polyorganosiloxane emulsion generally comprises 10 to 60% by weight of polyorganosiloxane, the remainder generally being the product (Z), the surfactant (Y) and water. The amount of surfactant (Y) in the emulsion is generally between 0.1 and 15% by weight and preferably between 0.25 and 2% by weight relative to the total weight of the emulsion. The amount of product (Z) is generally between 0.1 and 15% by weight and preferably 0.25 and 5% by weight relative to the total weight of the emulsion.

The product (Z) can be prepared by reacting the carboxylic acid (Zb) and the amine (Za) in water, optionally hot (25 ° C to 75 ° C). The compounds (Za) and (Zb) are advantageously in equimolar amounts or close to equimolarity, for example being able to range at least up to 1.2 mole of carboxylic acid, in particular stearic, for 1 mole of amine, in particular of 2-amino-2-ethylpropane-1,3-diol. Preferably, the metal, in particular zirconium, of the crosslinking agent is introduced in the following amounts: the ratio between the number of moles of zirconium and the number of moles of the product (Z) is between 0 and 2, from preferably between 0.05 and 1. It is preferable to add water to the mixture of compounds (Za) and (Zb). Preferably, the water and the compounds (Za) and (Zb) are heated to a temperature of 70 to 75 ° C, with gentle stirring. In the case where a crosslinking agent is used, this agent is then added with stirring, preferably after cooling to between 20 and 35 ° C.

The emulsion can be produced in different ways, for example by phase inversion or by the direct method which consists in pouring the polyorganosiloxane into the mixture of the product (Z) and the surfactant (Y) and water under shear. In both cases, conventional batch emulsification technologies such as shear mixers, or continuous emulsification such as a colloid mill or high pressure homogenizer, for example Manton Gaulin homogenizer, are used. Optionally, the polyorganosiloxane can be emulsified with the product (Z), or the surfactant (Y), firstly, then the surfactant (Y) or the product (Z) is added respectively to the case. emulsion already made. The emulsion can also be prepared in the simultaneous presence of the product (Z) and of the surfactant (Y). It should be noted that in the case where the carboxylic acid (Yb) used is solid, for example stearic acid, it should be melted during its addition in the preparation of the emulsion.

According to a third variant of the invention, the process according to the invention uses a silicone compound which is a silane or a silane oligomer (c) of formula (IV).

Preferably, the molecular weight of the silane or of the silane oligomer is between 100 and 500 g and in formula (IV):

- R ', identical or different, are monovalent organic radicals, in particular linear or branched alkyl or alkenyl in to C₁₅ optionally substituted with a halogen group (F, Cl, Br), an epoxidized group, an amino group, these groups R 'preferably being a methyl, vinyl and / or octyl group, and

- u is equal to 1 or 0.

The silane or the silane oligomer (c) can be in solution in a liquid phase. This liquid phase is preferably an organic solvent, which can be chosen from the solvents for silicone polymers, such as those defined above. The choice of the liquid phase is made according to its compatibility with the silane. It is thus possible to play on the transparency of the final coating. In this case, a crosslinking catalyst can be added to the silane or the silane oligomer (c). This crosslinking catalyst can be chosen from organic titanium or tin compounds, in particular alkyl titanates and dialkyltin dicarboxylate.

According to a preferred implementation of the invention, the silane or the silane oligomer (c) is in the form of an emulsion in aqueous phase. This aqueous emulsion preferably comprises:

• at least one silane or silane oligomer of formula (IV), • the product (Z) of the reaction between:

- (Za) at least ammonia and / or an aromatic and / or aliphatic polyfunctional amine soluble in water containing from 2 to 25 carbon atoms,

- (Zb) at least one carboxylic acid or anhydride containing from 3 to 22 atoms.

The aromatic and / or aliphatic amines, the carboxylic acids or anhydrides and the crosslinking agents are identical to those defined above in the context of the aqueous polyorganosiloxane emulsion.

The aqueous silane emulsion can also comprise at least one surfactant chosen from the surfactants (Ya), (Yb) or (Yc) defined above.

For a detailed description of the silanes, reference may be made in particular to documents US Pat. No. 3,294,725; US-A-4,584,341; US-A-4,618,642; US-A-4,608,412; US-A-4,525,565; EP-A-387157; EP-A-340 120; EP-A-364,375; FR-A-1,248,826; and FR - 1 023477. More precisely, by way of examples, mention may be made of the following alkoxysilanes: Si (OC₂H₅)₄ ; CH₃If (OCH₃)₃ ; CH₃If (OC₂H₅)₃ ; (VS₂H₅O)₃If (OCH₃); CH₂= CHSi (OCH₃)₃ ; CH₃(CH₂= CH) If (OCH₃)₂ ; CH₂= CHSi (OC₂H₅)₃ ; CH₂= CHSi [ON = C (CH₃)VS₂H₅]₃; CH₃Si [ON = C (CH₃)₂]₃ ; CH₃If [-C (CH₃) = CH₂]₃ ; C ^H ^ SifOCH); methyltri (N-methylacetamidosilane); methyltris (cyclohexylaminosilane); isoC₄H₉If (OCH₃)₃ ; isoC₄H_gIf (OC₂H₅)₃ ; VS₈H₁₇If (OCH₃)₃ ; VS₈H₁₇If (OC₂H₅)₃ ; VS₂H₅If (OCH₃)₃ ; VS₂H₅If (OC₂H₅)₃ ;

VS₄^H9^Si (°^CH3)₃ ; VS₄H₉If (OC₂H₅)₃ and (CH₃)₂If (OCH₃)₂.

The aqueous silane or silane oligomer emulsion (c) may also comprise:

- at least one surfactant (Y) of (Ya), (Yb) or (Yc) type, and / or

- at least one crosslinking agent which is a hydrolubic metal, and / or

- at least one metal hardening compound.

These compounds are identical to those defined above for aqueous emulsions of polyorganosiloxanes.

Preferably, the emulsion comprises 10 to 60% by weight of silane or silane oligomer of formula (IV), the remainder generally being the product (Z), water and optionally Γ surfactant (Y ). The amount of product (Z) in the emulsion is generally between 0.1 and 15% by weight, and preferably between 0.25 and 5% by weight, relative to the total weight of the emulsion. If present, the amount of surfactant (Y) in the emulsion is between 0.1 and 15% by weight, and preferably between 0.25 and 5% by weight, relative to the total weight of the emulsion .

The product (Z) is prepared, as indicated above, in the context of the polyorganosiloxane emulsion.

The aqueous silane or silane oligomer emulsion (c) can be produced in different ways, for example by phase inversion or by the direct method which consists in pouring the silane into a mixture of product (Z), of surfactant. -active (Y) and water under shear. In both cases, conventional batch emulsification technologies such as shear mixers, or continuous emulsification such as a colloid mill or high pressure homogenizer, for example Manton Gaulin homogenizer, are used. Optionally, the silane can be emulsified with the product (Z) or the surfactant (Y) at first, then the surfactant (Y) or the product (Z) is added as appropriate to the emulsion already made. The emulsion can also be prepared in the simultaneous presence of the product (Z) and of the surfactant (Y). It should be noted that in the case where the carboxylic acid used is solid, for example stearic acid, it should be melted during its addition in the preparation of the emulsion.

According to the process of the invention, it is also possible to use, as silicone compound, an aqueous emulsion comprising a mixture of silicone compounds (b) and (c). This emulsion can be made:

- either by mixing an aqueous emulsion of polyorganosiloxane (b) of formula (II) or (III), preferably defined according to the third embodiment of formula (III), and an aqueous emulsion of silane or oligomer of silane (c) of formula (IV),

- or by mixing at least one polyorganosiloxane (b) of formula (II) or (III), preferably defined according to the third embodiment of formula (III), and at least one silane or silane oligomer (c) of formula (IV), then emulsification of the mixture obtained according to the emulsification processes defined above.

In all cases, the emulsion preferably comprises 10 to 60% by weight of the mixture of polyorganosiloxane and silane, the remainder generally being the product of reaction (Z), water and the surfactant ( Y) if present. The polyorganosiloxane / silane weight ratio is generally between 0 and 20 and preferably between 0.1 and 9. The amounts of product (Z) and of surfactant (Y) are as defined above.

The method according to the invention has the advantage of using low cost products. It also makes it possible, under certain conditions of use, to lead to transparent or translucent coatings.

If the silicone compounds have intrinsic properties, such as for example protection of substrates (water repellency), it was observed that the fact of using them according to the process of the invention did not modify their properties because they are photoresist.

This is the case, for example, of the coating using the polyorganosiloxane of formula (III), the third preferred mode, which makes it possible to obtain a coating which adheres firmly to the alkaline substrate and also provides a water-repellent property specific to this type of polyorganosiloxane binder.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES

EXAMPLE 1

An aqueous dispersion at 4% by weight of dry extract of reference dioxide nanoparticles S5 300 B marketed by RHODIA CHIMIE is used. Its pH is 10.8.

A silicone compound is also used which is an aqueous emulsion of polyorganosiloxane of formula (III), third mode: DT (OR) with D = u, "5y" U, Ov> jl / Z υ, ΟΟΊ (θΗ₃)₂θίθ2 / 2 ^{and T = C}3^H7^SiO3/2 'polyorganosiloxane is emulsified with amine stearate (1% by weight relative to the polyorganosiloxane) and Rhodasurf ROX marketed by RHODIA CHIMIE (0.5%) [mixture of 2 surfactants: amine stearate (anionic) (Z) and nonionic (Rhodasurf ROX) (Yb)]. The composition of the emulsion is as follows:

<td>Amino 2 ethyl 2 propane diol 1,3 (AEPD)</td><td>eg</td>

<td>Stearic acid</td><td>14.05 g</td>

<td>Rhodasurf ROX (85%)</td><td>11.44 g</td>

<td>Polyorganosiloxane of viscosity = 50 mm²/ s</td><td>606 g</td>

<td>Demineralized Water</td><td>1317.3 g</td>

<td>Total mass</td><td>1954.79 g</td>

The emulsion is produced as follows:

- the Mariton-Gaulin device is preheated with hot water (50 ° C),

- the pre-emulsion is prepared in a 3 l stainless steel beaker by loading the AEPD + stearic acid + the ROX surfactant + the polyorganosiloxane,

- Mixing with a propeller and simultaneously heating to 60 ° C. Then, water is added dropwise using a turbine until inversion (increase in viscosity and white color),

- the inversion is carried out after pouring 210 ml of water. After casting, the mixture is stirred and sheared for approximately 10 min.

- the rest of the water is poured. An emulsion with a particle size of 1.945 μm is obtained.

- This emulsion is passed through the Manton Gaulin homogenizer under a pressure of 200 bars (1 single pass).

The final average particle size is 0.684 μm, the dry extract (2 g at 120 ° C. for 1 hour) is 29%.

The emulsion is diluted to 6% by weight of polyorganosiloxane for the application.

The substrate to be treated is a concrete slab. The solution of titanium dioxide particles is first applied with a brush at a rate of 100 g of dispersion / m². The concrete is then left to dry for approximately 1 hour at 25 ° C.

Then, the polyorganosiloxane emulsion is applied with a brush at a rate of 100 g of emulsion / m². The concrete is then allowed to dry for 4 days at 25 ° C.

This treatment is called treatment 1.

The appearance of the concrete was not modified by treatment 1.

Measurement of photocatalytic activity

The treated concrete is stained with used drain oil such as TOTAL ACTIVA 5000 by applying oil at a rate of 30 g / m² over the entire surface of the slab. Then, the slab is subjected to UV irradiation using a UVA 340 lamp which emits radiation of 295 to 340 nm (solar spectrum).

The evolution of the degradation of the stain is monitored using a CS-3 CHROMA SENSOR type spectrocolorimeter from DATACOLOR. The lightness index L is thus measured (for the white color L = 100 and for the black color L = 0).

Graph 1 represents the change in DL as a function of the irradiation time, DL representing the difference between the lightness index of the unstained initial treated support and the lightness index of the stained support at time t. The more DL tends towards 0, the more the support regains its initial appearance.

The reference corresponds to an untreated but stained control.

The results are given in FIG. 1: it is observed that the degradation of the used oil stain under the photocatalytic action of the titanium particles begins after 800 hours of exposure. After 2400 hours of exposure, the stain has almost completely disappeared compared to the untreated control for which the surface remains completely stained.

Measurement of the hydrofuqeante activity:

The water-repellent properties of the treated substrate are checked by measuring the water uptake in a Karsten tube (APL H&amp;B T222 test) for 2 days. The results appear in Figure 2.

It is noted that the water absorption is only 0.09 ml in 2 days for the treated concrete, while the untreated control absorbs 0.5 ml in 6 hours.

The substrate treated according to the invention is therefore water-repellent and self-cleaning.

EXAMPLE 2

The same dispersion of titanium dioxide particles and the same polyorganosiloxane emulsion as in Example 1 are used.

The substrate and the processing conditions of the substrate are the same as in Example 1.

Measurement of photocatalytic activity

The concrete is sprayed with water for 2 minutes to simulate rain. The treated concrete is stained with used drain oil such as TOTAL ACTIVA 5000 by applying oil at a rate of 30 g / m² over the entire surface of the slab. Then, the slab is subjected to UV irradiation using a UVA 340 lamp which emits radiation of 295 to 340 nm (solar spectrum). After 900 hours of irradiation, the support is subjected to a new simulation of rain by spraying water for 2 minutes, then the UV irradiation is recommenced.

The results appear in FIG. 3. It is observed that the untreated control remains stained. It is noted that the degradation is not disturbed by the washing cycles, the titanium dioxide particles are therefore well fixed on the substrate thanks to the polyorganosiloxane resin emulsion.

EXAMPLE 3

An aqueous dispersion of titanium dioxide nanoparticles of reference S5 300 B sold by RHODIA CHIMIE at 5% by weight of dry extract is used. Its pH is 10.8.

A silicone compound sold under the name RHOXIMAT® SILICONATE 51T is also used, which is a potassium methylsiliconate in aqueous solution initially exhibiting at 47% by weight of dry extract and diluted to 5% for the application.

The substrate to be treated is a terracotta tile. The solution of titanium dioxide particles is first applied with a brush at a rate of 100 g of dispersion / m^z. The tile is then allowed to dry for approximately 1 hour at 25 ° C.

Then, the potassium methylsiliconate is applied with a brush at a rate of 100 g of solution / m². The tile is then left to dry for 4 days at 25 ° C.

This treatment is called treatment 2.

The appearance of the support is not modified by this treatment.

Measurement of photocatalyst activity

The protocol of Example 1. The results appear in FIG. 4.

It is observed that the degradation begins after 400 hours of irradiation and that the support practically regains its initial appearance after 800 hours.

Measurement of hvdrofuqeante activity:

The water-repellent properties of the treated substrate are checked by measuring the water uptake in a Karsten tube (APL H&amp;B T222 test) for 2 days. The results appear in Figure 5.

It is observed that the water absorption is only 0.3 ml in 2 days for the treated concrete, while the untreated control absorbs the 20 ml of the Karsten tube in a few minutes.

The substrate treated according to the invention is therefore water-repellent and self-cleaning.

EXAMPLE 4

The same dispersion of titanium dioxide particles and the same siliconate solution as in Example 3 are used.

The substrate and the processing conditions of the substrate are the same as in Example 1.

Measurement of photocatalyst activity

The concrete is sprayed with water for 2 minutes to simulate rain. The treated concrete is stained with used drain oil such as TOTAL ACTIVA 5000 by applying oil at a rate of 30 g / m² over the entire surface of the slab. Then, the slab is subjected to UV irradiation using a UVA 340 lamp which emits radiation of 295 to 340 nm (solar spectrum). After 900 hours of irradiation, the support is subjected to a new simulation of rain by spraying water for 2 minutes, then the UV irradiation is recommenced.

The results appear in FIG. 6. It is observed that the untreated control remains stained. It is observed that the degradation is not disturbed by the washing cycles, the titanium dioxide particles are therefore well fixed to the surface thanks to the potassium methylsiliconate.