WO1999045052A1

WO1999045052A1 - Coating with two polyols, composition useful for such coatings and method for obtaining said coatings

Info

Publication number: WO1999045052A1
Application number: PCT/FR1999/000457
Authority: WO
Inventors: Thierry Jeannette; Evelyne Prat; Roland Reeb; Sylvie Touzet
Original assignee: Rhodia Chimie
Priority date: 1998-03-02
Filing date: 1999-03-02
Publication date: 1999-09-10
Also published as: AU2629499A; FR2775482A1

Abstract

The invention concerns a composition particularly useful for exterior finish, characterised in that it comprises by successive or simultaneous addition: an aqueous phase comprising a polyol solution or dispersion whereof the glass transition temperature (tg) is not more than 100 DEG C; an isocyanate sub-composition already or to be emulsified in the same aqueous phase and said polyol has at least two constituents.

Description

1

COATINGS WITH TWO POLYOLS, COMPOSITION USEFUL FOR SUCH COATINGS AND PROCESS FOR OBTAINING SUCH COATINGS

The subject of the present invention is a coating for exterior or industrial floor, a composition useful for such coatings and the process for obtaining these coatings.

It relates more particularly to the association of certain polyols with certain forms of isocyanate.

The coatings described in the invention are particularly advantageous for application on metallic supports but they solve a problem especially for non-metallic supports among which mention may be made of plant supports such as wood and mainly mineral supports, of variable porosity, of the type concrete, plaster, stone, phosphomagnesium support. It is thus possible to obtain coatings with controlled permeability (waterproof (impermeability to liquids) while allowing the support to breathe [permeability to gases]) whose penetration depth in the support and flexibility can be adjusted, by playing in particular on the size and the Tg of the polyol as well as the nature of the surfactant used. These coatings can be applied without problem on damp substrates.

These coatings can be used indoors or outdoors, on horizontal or vertical walls with success in particular: o as a finishing layer for industrial floors (in general, mineral or wood support): resistance to abrasion is improved, and l 'water permeability is reduced, which makes it possible to obtain durable, easy-to-maintain soils; o as a waterproof coating: a flexible waterproof coating can be produced by impregnation which can be applied outdoors at low temperature in the presence of moisture, without causing any cracking problem.

The term "coating" means in particular:

REPLACEMENT OIL (RULE 26) reduce soiling, facilitate cleaning, improve wear resistance and strengthen mechanical properties.

The impregnation resins known in the art are based on epoxides, polyurethanes, polymethylmethacrylate, or polyester.

2) Paints, coatings (stricto sensu)

These are thin films of at least about 10 ^~ 2 mm, generally 0.1 to 1 mm based on synthetic epoxy resins, polyurethanes, methacrylates, used alone or in combination and which generally contain fine fillers and pigments.

They are applied on horizontal or vertical supports, by brush, roller, squeegee or by spraying.

In the case of application on a horizontal support, semi-thick coatings can be obtained by sprinkling fillers on a fresh layer. These floor coverings are intended, like impregnating resins, to reduce the porosity of the support, thereby reducing the formation of dust, facilitating cleaning, improving resistance to abrasion, resistance to aggressive chemical agents: acids , bases, solvents, oils ...

3) Synthetic resin screeds (including self-leveling coatings)

Self-leveling floors can consist of mixtures of resins and fillers applied on thicknesses of 1 to 3 mm and floats, which give the floor a smooth appearance (removal of macro roughness) and / or which can be made non-slip by dusting fillers (silica, corundum ...).

Synthetic resin screeds are applied on greater thicknesses (4 mm to 1.5 cm).

It is necessary to obtain a coating having very good mechanical and chemical characteristics and a beautiful aesthetic appearance. It is particularly necessary to obtain high compressive and flexural strengths (R _CO mpression: 60 to 120 MPa - Rf | _ex jon: 28 to 45 MPa).

The screeds must be particularly resistant to abrasion, indicated in the case of heavy traffic, and also have good chemical resistance to attack.

One of the aims of the present invention is to provide polyurethane resins which make it possible in particular to obtain flexible coatings, which mask the existing cracks in the support and which make it possible to resist the cracks induced by the support.

Such compositions are particularly useful for varnishes (the constraints of which they lend themselves particularly well) but also for painting. More generally, they can be useful for any application using the condensation properties of isocyanates.

In the remainder of this description, the term dispersion will be used for polymers containing hydroxyl functions and in particular polyols, however, the expression emulsions will be used for isocyanates, blocked or not.

The use of organic solvents is increasingly criticized by the authorities responsible for occupational safety, because these solvents, or at least some of them, are known to be toxic or chronotoxic. This is the reason why we are trying to develop more and more techniques which replace the techniques in a solvent medium or which make it possible to reduce the quantity thereof to overcome the drawbacks relating to solvents.

One of the most often used solutions is the use of emulsions or dispersions in water.

To make films of paints or varnishes, two dispersions are mixed, an emulsion containing the isocyanate which can be blocked and a polyol dispersion.

The mixture of dispersions which may also contain pigments and fillers is then deposited on a support in the form of a film using conventional techniques for using industrial resins or paints. When the preparation contains blocked isocyanates, the film plus support assembly is cooked at a temperature sufficient to ensure the release of the isocyanate functions and the condensation of these with hydroxyl groups of the polyol particles. However, such techniques are almost impossible to carry out outdoors. In the present description, the particle size characteristics often refer to notations of the type d _n where n is a number from 1 to 99, this notation is well known in many technical fields, but is a little more rare in chemistry, also may it be useful to recall its meaning. This notation represents the particle size such that n% (by weight, or more exactly by mass, since the weight is not an amount of matter but a force) of the particles is less than or equal to said size.

In the following description, we will use the polydispersity index, which is defined as: I = (go- ^ 0) ^ 50 Typically, the ratios of the average sizes, or else the dso) when it is determinable, between the isocyanate emulsion and the polyol dispersion are between 2 and 200. Thus the average sizes of the isocyanate emulsions manufactured according to the technique described in the French patent application filed on March 31, 1993 under No. 93 03795 and published under No. 2703358 on October 07, 1994, have average sizes between 0.1 and 10 micrometers and more generally between 0.3 and 2 micrometers. The polyol dispersions used in association with these emulsions have average sizes measured by quasi-elastic light scattering of between 20 and 200 nanometers and more generally between 50 and 150 nanometers.

When mixing dispersions of different sizes, which is generally the case, so as to obtain molar ratios between the NCO and OH groups of between 0.3 to 10 and more preferably between 0.8 and 1.5 , an instability of the mixtures of the two dispersions is observed. By way of example, this instability results in rapid macroscopic separation, generally in a few minutes, to give on the one hand a fluid phase and on the other hand a very viscous phase.

It follows not only an impossibility of preserving (storing) these mixtures, but also an extreme difficulty in applying this mixture on the surface which it is desired to cover or impregnate according to the usual techniques for applying paints and varnishes. If we make sure to apply these unstable mixtures on a support, such as on a glass or metal plate, the resulting film is not transparent but appears opaque and heterogeneous and therefore not suitable. These problems are particularly acute in the case of isocyanates, masked or not, when they are mixed with non-soluble polyols dispersed in water.

In addition in the case of coatings intended for the exterior, the coating must be resistant to weathering and in particular to significant temperature variations which can be of the order of 30 to 50 ° C., or even even 80 ° C. [for example between -20 and + 60 ° C].

This is why one of the aims of the present invention is to provide a composition which makes it possible to produce quality exterior coatings or paints which are resistant to bad weather. Another object of the invention is to provide a composition which makes it possible to produce industrial floor coverings as described above (impregnating resin, self-leveling coatings, resin screeds, etc.) making it possible in particular to: = t> reduce the porosity of the support to water, while letting the steam pass; increase dust resistance and ease of cleaning; > increase resistance to chemical attack (acids, solvents, ...); > to improve the mechanical properties of the support and to reinforce its resistance to abrasion.

Another object of the present invention is to provide a composition of the above type which requires little or no solvent.

Another object of the present invention is to provide a composition, in particular a varnish, capable of protecting architectural concretes. Another object of the present invention is to provide a composition, in particular a varnish, capable of adhering well even in a humid environment.

Another object of the present invention is to provide a composition of the above type which is quickly (at most two hours,) without dust.

These aims and others which will appear subsequently are achieved by means of a composition which is useful in particular for exterior coatings, characterized in that it comprises, for successive or simultaneous addition:

• => An aqueous phase comprising a solution or dispersion of polyol (s) whose glass transition temperature (tg) is at most equal to 100 ° C., "=> An isocyanate sub-composition already or to be emulsified in the same aqueous phase and the fact that said polyol has at least two components. It is desirable that said polyol is in the form of several dispersions in the same continuous phase thus constituting several latexes (population of particles of the same composition)

Recall that a latex is a population of particles of the same composition dispersed in a continuous phase; in the present description, when there are several populations [one population per composition] in the same continuous phase, it will be considered that there are several latexes) has a glass transition temperature (tg) of between −50 ° C. and + 40 ° C; in the event of mixing, this constraint applies to at least one of the latexes, preferably to all of them.

When using high tg latex, rigid coatings of high hardness are obtained, which are particularly suitable for industrial floors. For better flexibility (in particular elongation at break) and better weather resistance (rapid variation of the outside temperature in particular during a single nycthemer [day-night cycle]), it is desirable that the polyol, or minus one of the polyols when there are several, has a t _{g of} less than 0 ° C, advantageously at -10 ° C, preferably at -20 ° C, see -30 ° C in very rigorous countries;

For good adhesion to the support, a tg (in the case of a latex mixture of at least one of the latexes) at most equal to the application temperature (of the precursor composition of the coating on the support) is recommended.

To make films of paints or varnishes, a mixture of two dispersions is used in a (same) continuous phase. These dispersions form two populations of particles; one, the emulsion containing the isocyanate which can be blocked, and the other, a polyol dispersion. This mixing can be carried out by mixing a suspension and a dispersion, but more generally by dispersing a second constituent in the continuous phase of a first. Most often the isocyanate is emulsified in the aqueous phase of the polyol dispersion.

It is desirable that the polyol (s) dispersions used in combination with these emulsions have average sizes measured by quasi-elastic light scattering at least equal to approximately 10 nm, advantageously approximately 20 nm, preferably approximately 50 nm and at most equal to about 200 nanometers, advantageously 150 nanometers and preferably at most 100 nm. Obtaining polyol and in particular latex polyol with variable glass transition temperature (high or low) can be carried out by varying the level of co-monomer (s) giving rigid homopolymers and the rate of those giving flexible homopolymers. Thus the replacement of methyl methacrylate by butyl acrylate makes it possible to significantly lower the glass transition temperature and to reach the above values.

Advantageously, the polyol can contain ionic carboxylic or sulfonic groups, but it can also not contain an ionic group.

In the context of the present invention, it has been shown that the presence of anionic carboxylate function (-CO2 ") significantly increases the drying kinetics which is particularly advantageous for obtaining a rapid" dust-free ", in particular when operating A significant effect can be noted for a ratio of at least one carboxylic function for approximately 20 reactive hydrogen functions [alcohol or phenol function], advantageously for a ratio of one for approximately 10, preferably for a ratio of one for approximately 5; it is however desirable that this ratio is (for the case of several polyols, on average and / or for the polyol richest in alcohol function) at most equal to a function for a function , preferably of a carboxylic function for two ol functions. The counter cations of the carboxylates advantageously correspond to the same preferences as those expressed for the counter cations of the compound according to the present invention.

The polyol can already be in an aqueous or water-soluble or water-dispersible medium. it may be an aqueous solution (which can in particular be obtained after neutralization of the ionic groups) or an emulsion of the polymer in water or a dispersion of the latex type.

Thus one can envisage various implementations of the present invention. According to a particularly advantageous implementation of the present invention, said polyol is in the form of several latexes (population of particles of the same composition), at least one of which has a glass transition temperature (tg) at most equal to the temperature of application.

Thus more often than not, it is desirable for said polyol to be in the form of several latexes (population of particles of the same composition) of which at least one has a glass transition temperature (t _g ) at most equal to ambient temperature ( about 20 ° C), preferably at 10 ° C.

According to an advantageous variant of the present invention, said polyol is in the form of several latexes of which at least one (or more) has a glass transition temperature (tg) at most equal to the application temperature of said polyol and represents (nt) a mass fraction at least equal to

Advantageously to 1/3, preferably to 2/5.

To withstand severe cold, according to an advantageous option of the present invention, the components of said polyol have a glass transition temperature (t _g ) at most equal to 0 ° C, advantageously at -10 ° C, preferably at -20 °. C, even at -30 ° C.

More specifically, it is advised that said polyol is in the form of several latexes, at least one (or more) of which has a glass transition temperature (tg) at most equal to 0 ° C., advantageously at -10 ° C., preferably at -20 ° C, even at -30 ° C and represents (s) a mass fraction at least equal to 1/4, advantageously 1/3, preferably 2/5.

According to an advantageous implementation of the present invention, said polyol is formed from at least two latexes, at least one of which has a low hydroxyl content, the percentage by mass of latex with low hydroxyl content being between (range closed) 10 and 90% and advantageously between 10 and 50%, preferably between 10 and 40%.

Advantageously, in said polyol formed from at least two latexes, at least one of which has a glass transition temperature (t _g ) at least equal to 8

20 ° C, advantageously at -10 ° C, preferably at -20 ° C, even at -30 ° C, the percentage by mass of latex at low t _g is between (closed range) 10 and 90% and advantageously between 10 and 50%, preferably between 10 and 40%. The above notions are detailed below. However, the preferred polyols for the invention are latexes as described below.

It seems possible to disperse a standard polyisocyanate in a water-soluble polyol under certain formulation conditions (in particular with a suitable pigment to paint binder ratio). However, the use of standard polyisocyanates with hydrodispersed polyols (resin emulsion or latex types) often poses incompatibility problems (flocculation, appearance of several phases, etc.). One of the many advantages of the preparation according to the invention is that it offers great freedom of choice for the formulation (physical form of the polyol, pigment to binder ratio, ease of incorporation into aqueous media).

On the other hand, it was found through use values of the coatings (in particular chemical resistance and hardness) that the crosslinking of the films was much greater when the polyol used was carboxylated.

In particular, it is advantageous to use latexes, in particular nanolatexes (that is to say latex whose particle size is nanometric [more precisely whose dso is at most equal to approximately 100 nanometers]).

Thus, according to one of the particularly advantageous embodiments of the present invention, the polyol is advantageously a latex of nanometric size having the following characteristics: = "do (or more often mean diameter) between 15 and 60 nm, advantageously between 20 and 40 nm <=> solid content (in polyol, that is to say excluding isocyanate, filler [for example pigment] and adjuvant): between 10 and 50, advantageously between 25 and 40% • => an O _Q O less than 1 micrometer.

The following values relate to the use of a polyol alone, otherwise they are average values:

=> carboxylate function from 0.5 to 5% by mass (COO "= 44)

^ ol function: at least 1, advantageously at least 1.5, preferably at least 2% and at most 6%, advantageously at most 4%, preferably at most 3% (by mass OH = 17).

In addition, latexes, especially when their glass transition point is less than 0 ° C, advantageously at -10 ° C, preferably at -20 ° C, allow even obtaining with good quality aromatic isocyanates resistance to weathering and in particular to temperature variations, particularly suitable for exterior coatings or coatings deposited on supports already having cracks or likely to crack.

It may be particularly advantageous to adjust the flexibility of the coatings by playing with the tg of the latex.

Also a high tg latex can provide rigid coatings with improved mechanical properties. According to a particularly advantageous implementation of the present invention, a polyol dispersion mixture (latex mixture) is used comprising at least two polyols (two latexes) or classes of polyols associated two by two.

It is thus possible to combine it with a latex (or with several latexes) A having a content (in percent by mass) in OH function accessible at least equal to 1%

(approx. 0.3 miliequivalent per gram), advantageously at 1.5%, preferably at

2%, a latex (or several latexes) B poor in alcohol function (less than 1%, advantageously 0.8%, preferably 0.5%).

It is possible to combine a latex with a tg higher than the ambient (about 20 ° C.) with a latex (which may advantageously be the, one of, or the latex B above) with a tg lower than the ambient, advantageously at 10 ° C preferably at 0 ° C, more preferably whose tg is between -10 ° C and -40 ° C.

It is also possible to mix latexes of different particle sizes to improve the filling coefficient. These latexes can be used simultaneously or successively. Thus, it is advantageously possible to constitute a type B latex precoat before using the composition formed from latex A and isocyanate emulsified according to the invention.

The ratio between the latexes can vary between 90/10 and 10/90, but it is preferable that the average content of OH function (mass = 17) is at least equal to a value between 1 and 5, advantageously between 1, 5 and 4, preferably between 2 and 3%.

We consider as accessible the carboxylic functions which are at most 5 nanometers from the surface, and the hydroxyl (alcoholic) functions which are at most 10 nanometers from the surface [continuous particle-phase interface (most often aqueous) for latexes. ]. 10

The molar ratio between the free isocyanate functions and the hydroxyl functions is between 0.5 and 2.5, advantageously between 0.8 and 1.6, advantageously between 1 and 1.4.

The latexes (not functionalized in isocyanate optionally masked) described in the French patent application filed April 28, 1995 No. 95/05123 and in the European patent reflex application EP 0.739.961 give very good results for better understanding of this passage we can refer to this text.

Thus advantageously the latex particles have on average an acid function content (advantageously carboxylic), accessible of between 0.2 and 1.5, advantageously between 0.2 and 1.2 milliequivalents / gram of solid matter and that they have on average, an accessible primary alcoholic content of between 0.3 and 2 milliequivalents / gram, advantageously between 0.3 and 1.5. Thus, as indicated in this document, preferred are latex consisting of particles carrying function (s) according to the invention, which are hydrophobic and advantageously have a size (dgrj) generally between 0.01 micrometer and 10 micrometers and preferably at most equal to 5 micrometers, or even to 2 micrometers. They are calibrated, monodispersed and present in the latex in an amount varying between 0.2 to 65% by weight of the total weight of the latex.

The weight average molecular mass (M _w, preferably determined by gel permeation chromatography, known by the acronym

"GPC") of the constituent polymers of the latex particles is advantageously between 5.10 ^ and 5.10 ^, preferably greater than 1.10 ^ and at most equal to 2.10 ⁶ .

The alcoholic functions or the acid functions, preferably carboxylic, can also be obtained by hydrolysis of alcohologenic functions (ester, ether, halide, etc.) or acidogenic functions (ester, anhydride, acid chloride, amide, nitrile, etc.). .).

The distribution between the different types of patterns advantageously meets the following rules.

The content of unit originating from the monomer constituted by said free alcohol having an activated ethylenic function, and related to all the units of any kind, is advantageously between 3 and 15%, preferably between 4 and 10% (mole, or equivalent ).

According to an advantageous embodiment of the present invention, the motif is derived from an ester, from an alpha ethylenic acid, with a diol of which one of the alcohol functions It remains unesterified. Said diol is advantageously an omega / omega prime diol, advantageously chosen from butanediol-1, 4, propane diol-1, 3 and glycol.

It is desirable that said alpha ethylenic acid is an optionally substituted acrylic acid. According to a preferred embodiment of the present invention, the content of unit originating from a free carboxylic acid (or in the form of one of its salts), and related to all the units of all kinds, is between 2 and 10% (mole).

For economic reasons, it is often advantageous for said free acid to be an optionally monosubstituted acrylic acid or one of its salts. The particles resulting from the present invention can consist of two distinct polymers, the first constituting the core and the second constituting the periphery. This type of particle can be obtained by epipolymerization [where a latex seed is covered by surface polymerization (epipolymerization, sometimes referred to as overpolymerization)] of a separate polymer. The heart is sometimes called a germ by analogy to the phenomenon of crystallization. In this case, only the second polymer, that is to say the surface polymer, meets the concentration constraints for the different functions according to the present invention. -

It is desirable that said isocyanate sub-composition be self-emulsifying (that is to say that it forms an emulsion with moderate stirring, for example stirring from Example 1).

This character can be brought by the grafting of a polyethylene oxide chain or preferably can be brought in the form of the compositions referred to by the international patent application published under the number WO97 / 31960.

As regards the isocyanates themselves, the following can be indicated.

It is preferred to use isocyanates having an average functionality of between 2.5 and 4 and whose viscosity is low (at most 1500 mPa.s, preferably at most 1000).

According to a particularly advantageous implementation of the present invention, after dispersion or emulsion, the sum of the constituents of the binder (that is to say the contents by mass of, or, isocyanates, emulsifiers and polyols) , in water varies from 10, advantageously from 30 to 70% relative to the whole of the composition.

The isocyanates targeted by the invention notably comprise the compounds detailed below. / 45052

12

These compounds can advantageously contain the structures common in this field, for example the prepolymers resulting from the condensation of polyol (for example trimethylol propane) in general triol (advantageously primary or even further on the definition of polyols) and especially the most common, namely those of the isocyanurate type, also called trimer, of the uretidine dione structures, also called the dimer, of the biuret or allophanate structures or of a combination of this type of structure on a single molecule or as a mixture.

If it is desired to greatly reduce the solvent content of the composition, in particular when it is in the form of an emulsion, it is preferable to use mixtures of this type naturally (that is to say without addition of solvent) at low viscosity. The compounds exhibiting this property are mainly the derivatives

(isocyanurate type, also called trimer, uretidine dione structures, also called dimer, biuret or allophanate structures or a combination of this type of structure on a single molecule or as a mixture) partly and / or entirely of aliphatic isocyanates, the isocyanate functions are linked to the backbone via ethylene fragments (for example polymethylenediisocyanates, in particular hexamethylenediisocyanate and those of arylenedialcoylediediocyanates whose isocyanate function is distant from the aromatic nuclei of at least two carbons such as (OCN- [CH2] t- - [CH2] _u -

NCO) with t and u greater than 1). These compounds or mixtures advantageously have a viscosity at most equal to approximately 3,000 centipoise (or millipascal.second), preferably to approximately 1,500 centipoise (or millipascal.second). When these values are not reached, it is then often useful to bring the mixture to these viscosity values by the addition of a minimum quantity of suitable solvent (s). As already mentioned above, the isocyanates concerned can be mono-, di- or even polyisocyanates.

Advantageously, these derivatives can contain isocyanurate type structures, also called trimer, uretidine dione structures, also called dimer, biuret or allophanate structures or a combination of this type of structures on a single molecule or as a mixture.

The monomeric isocyanates can be:

<= aliphatics, including cycloaliphatics and arylaliphatics, such as: • as simple aliphatics, polymethylenediisocyanates and in particular hexamethylene diisocyanate; • as partially cyclic (cycloaliphatic) partially "neopentyl" aliphatic isophorone diisocyanate (IPDI); 13

• as cyclic aliphatic (cycloaliphatic) diisocyanate those derived from the norbomane;

• the arylènedialcoylènediisocyanates (such as OCN-CH2-Φ-CH2- NCO of which a part does not present an essential difference with aliphatics namely those whose isocyanate function is distant from the aromatic nuclei of at least two carbons such as ( OCN- [CH ₂ ] t-Φ- [CH ₂ ] _u -NCO) with t and u greater than 1; ^c > or also aromatics such as toluylene diisocyanate. The preferred polyisocyanates targeted by the technique of the invention are those in which at least one, advantageously two, preferably three of the following conditions are met:

• At least one, advantageously at least two, NCO functions are connected to a hydrocarbon skeleton, via a saturated carbon (sp ^), preferably with at least one, more preferably at least two of the sub-conditions ci - after.

• At least one, advantageously two, of said saturated carbons (sp3) carries at least one, advantageously two, hydrogen (s), (in other words it has been found that better results are obtained when the carbon carrying the isocyanate function was carrying a hydrogen, preferably two hydrogens);

• at least one, advantageously two, of said saturated carbons (sp3) are themselves carried by a carbon, advantageously aliphatic (that is to say sp3 hybridization), itself carrying at least one, advantageously two, hydrogen (s); in other words, it has been found that better results are obtained when the carbon carrying the isocyanate function is not in the so-called "neopentyl" position;

• All of the carbons through which the isocyanate functions are linked to the hydrocarbon skeleton are saturated carbons (sp ^), which are advantageously partly, preferably entirely, carrying one hydrogen, preferably two hydrogens; in addition it is advantageous that said saturated carbons (sp3) are at least in part (advantageously one third, preferably two thirds), preferably entirely, themselves supported by a carbon, advantageously aliphatic (that is to say sp ^) hybridization, itself carrying at least one, advantageously two, hydrogen (s); in other words, it has been found that better results are obtained when the carbon carrying the isocyanate function is not in the so-called "neopentyl"position; 14

• Particularly well suited are those which at least partially have an isocyanuric or biuret skeleton (whether this skeleton is derived from one or more monomers, see below) and more specifically isocyanurate type structures, also called trimer , structures uretidinedione, also called dimer, structures biuret or allophanate or a combination of this type of structures on a single molecule or in mixture. When the polyisocyanates are relatively heavy, that is to say that they contain at least 4 isocyanate functions, the first two conditions become: "At least one third, advantageously two thirds, of the NCO functions are linked to a hydrocarbon backbone, by the intermediate of a saturated carbon (sp ³ ); .

• At least one third, advantageously two thirds, of said saturated carbons (sp ³ ) carries at least one, advantageously two, hydrogen (s) (in other words it has been found that better results are obtained results when the carbon carrying the isocyanate function was carrying a hydrogen, preferably two hydrogens; In addition it is advantageous that said saturated carbons (sp ³ ) are at least in part (advantageously one third, preferably two thirds ), preferably entirely, themselves carried by a carbon, advantageously aliphatic (that is to say sp ³ hybridization), itself carrying at least one, advantageously two, hydrogen (s); in other words, it has been found that better results are obtained when the carbon carrying the isocyanate function is not in the so-called "neopentyl"position;

Isocyanates, in particular aliphatic isocyanates, react with some of the anionic compounds targeted. They react with the hydroxyl of the acid functions which are not or badly neutralized. These compounds are also targeted by the present invention. Another object of the present invention is to provide a method of applying the isocyanate-based composition to form a coating.

These aims and others which will appear subsequently are achieved by means of a process comprising the application of a preparation layer (that is to say of a composition according to the invention comprising the aqueous phase and the constituents layer) whose thickness before drying will vary between 0.01 to 15 mm, depending on whether it is an impregnating resin, a paint, a self-leveling coating, or a resin screed. In the case of paints, the thickness before drying is at least 10 μm (micrometer), advantageously 50 μm 15

(micrometer), preferably 100 μm (micrometer) and at most equal to 1000 μm (micrometer), advantageously 400 micrometers, preferably 200 micrometers, corresponding after drying to a thickness of between 20 and 80, or even 200 micrometers. According to an advantageous implementation, this process comprises drying from 20 ° C to 60 ° C for a period which can range from 1/4 to 24 hours.

Advantageously, this drying takes place in the presence of a solvent to aid in the removal of the water.

According to a particularly advantageous implementation of the present invention, the application is carried out by spraying.

Surface preparation is well known to those skilled in the art (for example phosphating for ferrous steel compounds or chromating for aluminum-based surfaces), (for example, reference may be made to the following works: "organic coating technology" volume II of HF PAYNE and "Paint Handbook" Edited by GEWEISMANTEL).

For the specific case of concrete and stone substrates, a treatment will be carried out aimed at eliminating deposits or residues liable to reduce adhesion (milt, dust, waxes, curing products, organic soiling) by mechanical treatment (brushing, grinding, sandblasting, ...). According to the present invention, it is thus possible to obtain coatings

(in particular paints or varnishes) having the following technical characteristics (these values depend mainly on the polyols used):

99/45052

16

implementation and characteristics of the lso2178 dry coating thickness: 45 μm support and treatment of this: steel treated by phosphating: R46I plates from the supplier Q Pannel

usual minimal properties obtained

test din 67530 (these values are only useful when you want a glossy paint but not when you want matt or satin paint)

Gloss 20 ° 0.5 80

60 ° 0.5 90 hardness Kônig iso 1522 10s 150s

Adhesion test din 53151 GT-5 GT-1

Test shock resistance 10 cm> 100 cm ISO no 6272 direct reverse 5 cm> 100 cm

Resistance to methyl- 20> 200 ethyl ketone (butanone)

(Double pass)

Outdoor wear QUV 50 h 800 h Din 53384

Rhodafac® RE610 is a mixture of mono- and phosphoric diesters according to formula II, the average formula of its hydrocarbon radical is a polyethoxylated nonylphenol (~ ten times). The molar ratio between mono ester and diester is approximately 1 (mathematical rounding). 17

Example 1 - preparation of mixture 1

165 g of tolonate® HDT (trimer-based isocyanurate oligomer) are mixed with 24 g of butyl acetate and 13 g of Rhodafac® RE610 (mixture of phosphoric mono- and di-esters according to formula II) and 3 g triethylamine. This mixture is stirred using a paddle or deflocculator for 5 minutes at 100 revolutions / minute. This mixture has a viscosity of 0.84 Pa.s. At 20 ° C and a coloration less than 100 APHA.

Example 2 - Preparation of the mixture 2 79 g of tolonate® HDT (isocyanurate oligomer based on trimer) are mixed with 10 g of butyl acetate and 9 g of Rhodafac® RE610 (mixture of mono- and phosphoric diesters according to the formula II) and 1.4 g of triethylamine. This mixture is stirred using a paddle or deflocculator for 5 minutes at 100 revolutions / minute.

Example 3 - nanolatex 1

The nanolatex used is an experimental product produced according to the process described in the French patent application filed April 28, 1995 No. 95/05123 and in the European patent reflex application No. EP 0.739.961 with the following characteristics: diameter means evaluated by photometric counting (high resolution transmission electron microscopy): between 25 and 30 nm carboxylate function: 2.5% by weight on the dry polymer ol function: 2.5% by weight on the dry polymer Molecular mass greater than 100,000

Dry extract by weight: 29% pH about 8

Minimum Film Formation Temperature about 20 ° to 25 ° C Glass transition temperature about 40 ° C (between 40 ° C and 50 ° C)

Example 4 Preparation of a coating from mixture 1 and Nanolatex 1

The varnish is prepared by incorporating with manual mixing of 4.6 g of the mixture 1 into 45.6 g of nanolatex. This ratio corresponds to a ratio of the NCO / OH functions of 1.2.

The mixture thus prepared has a shelf life of 4 hours, this means that for 4 hours the viscosity and the appearance of the mixture is unchanged but also that the films formed from this mixture during these 4 hours have 18 properties like solvent resistance, hardness and gloss unchanged.

The drying time of the film is remarkably short: 20 minutes for the "dust-free" time and 30 minutes for the "dry to touch" time according to the NFT 30037 standard. These measurements were made on glass plates for a dry thickness of 40 μm film and drying at 23 ^C C with 55% relative humidity.

Achieving a short drying time and a relatively long lifetime of the mixture is an advantage much sought after by paint experts.

The values of use of the coating are also generally very good, we can cite:

- the Persoz hardness of the dry 50 μm film measured on a steel plate after drying for 24 hours at 23 ° C and 55% relative humidity is equal to 275 seconds,

- The gloss at an angle of 20 ° C of the film applied to the steel plate is equal to 90,

- the resistance to methyl ethyl ketone of the film dried for 7 days at 23 ° C and 55% relative humidity is greater than 200 round trips with a cotton pad,

- resistance to acids (sulfuric 20%, nitric 10%, hydrochloric 10%) is very good,

- the resistance to alcohols (ethanol) and to hydrocarbons (diesel) is also good, - the resistance to medium bases (ammonia 20%) is satisfactory.

These excellent performances of this Nanolatex-polyisocyanate association according to the invention are certainly attributable to the very specific physico-chemistry of these products, in particular to the very large specific surface area of the nanolatex which promotes great crosslinking homogeneity in the final polymer.

Example 5 - application on concrete support

The mixture prepared in Example 4 is applied by brush with a deposit of 200 g / m2 on a concrete-type support. After drying for 1 hour at room temperature, the coating offers water-repellency of the support, which results in a pearling effect, and less absorption of water. In addition, the coating has good abrasion resistance. 19

Example 6 - nanolatex 2

Nanolatex is an experimental product described in the French patent application filed on April 28, 1995 No. 95/05123 and in the reflex European patent application No. EP 0.739.961 with the following characteristic: d5Q about 35 nm carboxylate function : 1% by weight on the dry polymer ol function: 2.6% by weight on the dry polymer Molecular mass greater than 100,000 Dry extract by weight: 30% pH approximately 8 Glass transition temperature approximately -30 ° C

Example 7 Preparation of a coating from mixture 1 and nanolatex 2

The coating is applied to concrete with a brush at the rate of 2 layers of 300 g / m2. Its great flexibility, mainly generated by the low Tg of nanolatex, gives it an ability to mask the cracks that may appear during aging of the support (notably due to the expansion of concrete due to large temperature variations).

In addition, crosslinking with the polyisocyanate according to the invention gives the coating excellent resistance to chemical agents and to water.

The elongation at break of the film obtained is 4 times greater (40% against 10%) than in the case of latex 1 [cf. example N ° 4].

In addition, the coating has good or even excellent thaw-freeze cycle resistance, namely: <=> two hours at 60 ° C. with UV radiation and relative humidity less than 50%; ^" => Two hours at -20 ° C; two hours at 20 ° C with liquid water over the entire coated surface; ≈> two hours at -20 ° C; = two hours at 60 ° C with UV radiation and relative humidity below 50%; <=> two hours at 23 ° C with relative humidity above 95%. 20 the behavior is also good when submitting to the NF XPP18420 cycle

Example 8 - nanolatex 3 Nanolatex is an experimental product described in the French patent application filed April 28, 1995 No. 95/05123 and in the European patent reflex application No. EP 0.739.961 with the following characteristics: diameter means evaluated by photometric counting (high resolution transmission electron microscopy): between 25 and 40 nm carboxylate function: 2.5% by weight on the dry polymer ol function: 0.4% by weight on the dry polymer Molecular mass greater than 100,000 Dry extract by weight: 30% pH approximately 8 Minimum Film Formation Temperature approximately 0 ° C

Glass transition temperature around 16 ° C

EXAMPLE 9 Mixture of Nanolatex

75 g of nanolatex 1 (described in Example 3) are mixed with 25 g of nanolatex 3 (described in Example 8), with moderate stirring (three-blade agitator) for 5 min.

Example No. 10 - nanolatex mixture

50 g of nanolatex 1 (described in example 3) are mixed with 50 g of nanolatex 3 (described in example 8), with moderate stirring (three-blade agitator) for 5 min.

Example 11 - preparation and application of a coating from mixture 2 and nanolatex 1 The resin is prepared by incorporating 13 g of mixture 2 into 100 g of nanolatex 1 with moderate stirring (three-blade agitator) for 10 min. The ratio 13 g per 100 g corresponds to a ratio of NCO / OH functions of 1.2.

The mixture thus prepared has a pot life of at least 4 hours. The coating is applied to a fiber cement support using a pneumatic gun at the rate of approximately 200 g / m ² . 21

Example 12 - Preparation and Application of a Coating from Mixture 2 and the Nanolatex Mixture of Example 9

The resin is prepared by incorporating 9.75 g of the mixture 2 into 100 g of the nanolatex mixture of Example 13 with moderate stirring (three-blade agitator) for 10 min.

The mixture thus prepared has a pot life of at least 4 hours.

The coating is applied to a fiber cement support using a pneumatic gun at the rate of approximately 200 g / m ² .

Example 13 - Preparation and Application of a Coating from Mix 2 and the Nanolatex Mix from Example 10 The resin is prepared by incorporating 6.5 g of mixture 2 into 100 g of the nanolatex mixture of Example 14 with moderate agitation (three-bladed agitator) for 10 min.

The mixture thus prepared has a pot life of at least 4 hours.

Comparison of results: Adhesion of the coating to the Fibrocement support (support with closed pores)

The adhesion of the coating to the Fibrocement support was characterized by a grid test in accordance with ISO 2409. Two tests were performed on each coating:

- adhesion after air conditioning for 7 days at room temperature,

- adhesion after air conditioning for 7 days at room temperature then immersion for 7 days in water at room temperature.

The results are reported in the following table: 22

example 11 example 12 example 13 polyol with a high content of 100% -75% -50% alcohol and t _π ~ 40 ° C polyol with a low content of 0% -25% -50% alcohol function and t _n ~ 15 ° C

Dry adhesion Gt- 3 Gt- 1 Gt-1

Adhesion after immersion Gt- 5 Gt- 2 Gt-4-5

Comments the covering is torn off from torn off as soon as the wide strip is made during the incisions rapid peeling off of the adhesive tape

The coatings are all good when dry.

However those containing a bimodal mixture of polyols (two levels of content of ol functions) are better in dry adhesion.

In wet adhesion, the compound based on a single latex is particularly poor, for the others there is an optimum depending on the level of weakly hydroxylated latex. the mechanical properties are not affected by soaking and has good reversibility on drying.

Claims

23 CLAIMS

1. Composition useful in particular for exterior coverings, characterized in that it comprises, for successive or simultaneous addition:

"=> An aqueous phase comprising a solution or dispersion of polyol (s) whose glass transition temperature (t _g ) is at most equal to 100 ° C., • = An isocyanate sub-composition already or to be emulsified in the same aqueous phase and by the fact that said polyol has at least two components.

2. Composition according to claim 1, characterized in that said polyol is in the form of dispersions in a several m ^Λ me continuous phase constituting several latex (particle population of the same composition).

3. Composition according to Claims 1 and 2, characterized in that the said polyol is in the form of several latexes (population of particles of the same composition) of which at least one has a glass transition temperature (t _g ) at most equal to the application temperature.

4. Composition according to Claims 1 to 3, characterized in that the said polyol is in the form of several latexes (population of particles of the same composition) of which at least one has a glass transition temperature (t _g ) at most equal to room temperature (about 20 ° C), preferably 10 ° C.

5. Composition according to claims 1 to 4, characterized in that said polyol is in the form of several latexes of which one (or more) at least has a glass transition temperature (t _g ) at most equal to the temperature of application and represents (s) a mass fraction at least equal to 1/4, advantageously 1/3, preferably 2/5.

6. Composition for withstanding severe colds according to claims 1 to 5, characterized in that the said polyol is in the form of several latexes of which one (or more) at least has a glass transition temperature (tg) at more equal to 0 ° C, advantageously to -10 ° C, preferably 24 at -20 ° C, or even at -30 ° C and represents (s) a mass fraction at least equal to 1/4, advantageously 1/3, preferably 2/5.

7. Composition for withstanding severe colds according to claims 1 to 6, characterized in that the components of said polyol have a glass transition temperature (t _g ) at most equal to 0 ° C, advantageously at -10 ° C, preferably at -20 ° C, even at -30 ° C.

8. Composition according to Claims 1 to 7, characterized in that the said polyol is formed from at least two latexes, at least one of which has a low hydroxyl content, the percentage by mass of latex with low hydroxyl content being between (closed interval) 10 and 90% and advantageously between 10 and 50%, preferably between 10 and 40%.

9. Composition according to Claims 1 to 8, characterized in that the said polyol formed from at least two latexes, at least one of which has a glass transition temperature (t _g ) at least equal to 20 ° C, advantageously at -10 ° C, preferably at -20 ° C ,, or even at -30 ° C the percentage by mass of latex at low t _g being between (closed range) 10 and 90% and advantageously between 10 and 50%, preference between

10 and 40%.

10. Composition according to Claims 1 to 9, characterized in that the said isocyanate sub-composition is self-emulsifying (that is to say that it forms an emulsion under moderate agitation, for example agitation from Example 1).

11. Use of the composition according to claims 1 to 10 for the formation of a coating on a support of variable porosity.

12. Use according to claim 11, characterized in that said support is chosen from, non-metallic surfaces, facade coatings, lesmortier and plaster and so-called phosphomagnesium materials.

13. Use according to claim 12, characterized in that said support has closed porosity. 25

14. Use according to claim 13, characterized in that said support is of variable inclination.

15. A method of preparing a coating according to claim 14, characterized in that it comprises the application of a layer of a composition according to claims 1 to 10, between 20 and 200 micrometers (measured on dry )

16. The method of claim 15, characterized in that it comprises drying from 10 ° C to 50 ° C for 1/4 and 3 hours.

17. Method according to claims 15 and 16, characterized in that it comprises drying in the presence of a solvent to aid in the removal of water.

18. A coating capable of being obtained by a process according to claims 15 to 17.