FR2775482A1 - COATING WITH TWO POLYOLS, COMPOSITION USEFUL FOR THESE COATINGS AND PROCESS FOR OBTAINING THESE COATINGS - Google Patents

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

COATING WITH TWO POLYOLS, COMPOSITION USEFUL FOR THESE

  COATINGS AND METHOD FOR OBTAINING THESE COATINGS

  The present invention relates to a coating for outdoor or industrial floor, a composition useful for such coatings and process for obtaining

of these coatings.

  It relates more particularly to the combination of certain polyols with

  some isocyanate shaping.

  The coatings described in the invention are particularly interesting for application on metal support but it solves a problem especially for non-metallic supports among which may be mentioned plant supports such as wood and mainly mineral supports, of variable porosity,

  concrete type, plaster, stone, phosphomagnesium support.

  It is thus possible to obtain controlled permeability coatings (watertight [liquid impervious] while allowing the support to breathe [gas permeability]) whose depth of penetration into the support and the flexibility can be adjusted, while playing especially 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 wet substrates. These coatings can be used indoors or outdoors, on horizontal or vertical walls with success in particular: as a topcoat of industrial floors (in general, mineral support or wood): it improves the resistance to abrasion, and the the permeability to water is reduced, which makes it possible to obtain durable soils that are easy to maintain; * as a waterproofing coating: it is possible to impregnate a flexible waterproof coating that can be applied outdoors at low temperatures

  temperature in the presence of moisture, without causing cracking problem.

  By the term "coating" is meant in particular: 1) The "resins" of impregnation These products are intended to penetrate and fill the pores, to a depth varying from 0.1 to 3 mm and more depending on the porosity of the support,

generally from 0.5 to 3 mm.

  They are usually applied by spraying or brushing to help penetrate the support. Their function is to reduce porosity, reduce soiling, facilitate cleaning, and improve wear resistance

  and enhance the mechanical properties.

  The impregnating resins known in the art are based on epoxides,

  polyurethanes, polymethyl methacrylate, or polyester.

  2) Paints, coatings (stricto sensu) These are thin films of at least about 10-2 mm, usually 0.1 to 1 mm based on synthetic epoxy resins, polyurethanes, methacrylates, used alone or in combination, and usually contain

fine fillers and pigments.

  They are applied on horizontal or vertical supports, with a brush,

  roll, squeegee or spray.

  In the case of application on horizontal support, it will be possible to obtain

  sprinkling of fillers on a fresh layer, semiepais coatings.

  These floor coverings are intended, like the impregnating resins, to reduce the porosity of the support, thereby reducing the formation of dust, facilitating cleaning, improving the abrasion resistance, the

  resistance to aggressive chemical agents: acids, bases, solvents, oils ...

  3) Synthetic resin screeds (including self-leveling coatings) Self-leveling floors can be composed of mixtures of resins and fillers applied in thicknesses of 1 to 3 mm and floated, which give the floor a smooth appearance (removal of macro roughness) and / or who can

  be made anti-slip by dusting loads (silica, corundum ...).

  The synthetic resin screeds are applied on thicker

important (4 mm to 1.5 cm).

  It is necessary to obtain a coating having very good characteristics

  mechanical and chemical and a beautiful aesthetic appearance.

  In particular, it is necessary to obtain compressive and flexural strengths

  high (Compression: 60 to 120 MPa - Reflection: 28 to 45 MPa).

  The screeds must be particularly resistant to abrasion and indicated in the case of heavy traffic and also have good

  chemical resistance to aggression.

  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 of the support and which make it possible to resist

  cracking induced by the support.

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

  In the remainder of the present description, the term "dispersion" will be used.

  for polymers with hydroxyl functional groups and in particular polyols,

  that the expression "emulsions" for isocyanates, blocked or not, will be used.

  The use of organic solvents is increasingly criticized by the authorities in charge of safety at work, because these solvents, or at least some of them, are considered toxic or chronotoxic. This is the reason why we are trying to develop more and more techniques that replace the techniques in a solvent medium or that make it possible to reduce the

  amount to overcome the disadvantages associated with solvents.

  One of the most commonly used solutions is the use of

  emulsions or dispersions in water.

  To produce paint or varnish films, two dispersions are mixed, an emulsion containing the isocyanate which can be blocked and a

polyol dispersion.

  The mixture of dispersions may also contain pigments and fillers is then deposited on a support in the form of a film using the

  conventional techniques for using resins or industrial paints.

  When the preparation contains blocked isocyanates, the film plus support assembly is fired at a temperature sufficient to ensure the deblocking of the isocyanate functional groups 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 make

  often referred to notation of the type dn where n is a number from 1 to 99, this notation is well known in many technical fields, but is a little rarer in chemistry, so it may be useful to recall its meaning. This notation represents the particle size such that n% (in weight, or more exactly in mass, since the weight is not a quantity of matter but

  a force) of the particles is less than or equal to said size.

  In the remainder of the description, use will be made of the polydispersity index, which

  is defined as: I = (d90-d1 0) / d50 Typically, the ratios of the average sizes, or the d50) 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 31.03.1993 under No. 93 03795 and published under No. 2703358 on 07.10.94, have average sizes between 0 , 1 and 10 micrometers and more generally between 0.3 and 2 micrometers. The polyol dispersions used in combination with these emulsions have mean sizes measured by quasi-elastic light scattering of 20 to 200 nanometers or more.

  generally between 50 and 150 nanometers.

  When dispersions of different sizes are mixed, which is generally the case, so as to obtain molar ratios between the NCO and OH groups of between 0.3 and 10 and more preferably between

  0.8 and 1.5, instability of the mixtures of the two dispersions is observed.

  By way of example, this instability results in a rapid macroscopic separation, generally in a few minutes, to give a

  part of a fluid phase and secondly a very viscous phase.

  It follows not only an impossibility to keep (store) these mixtures, but also an extreme difficulty to apply this mixture on the surface that it is desired to cover or impregnate according to the usual techniques of application of paints and varnishes. If one makes 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 insoluble, dispersed polyols.

in water.

  In addition, in the case of coatings intended for outdoor use, the coating must be resistant to the weather and in particular to large temperature variations which may be of the order of 30 to 50 ° C., or even 80 ° C.

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 coatings or external paints.

  quality that withstands bad weather.

  Another object of the invention is to provide a composition which makes it possible to produce industrial floor coatings as described above (impregnating resin, self-leveling coatings, resin coatings, etc.) making it possible in particular to: reduce the porosity from the support to the water, while letting the steam pass; to increase dust resistance and ease of cleaning; to increase resistance to chemical attack (acids, solvents, ...); to improve the mechanical properties of the support and to reinforce its

abrasion resistance.

  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 of varnish, capable of protecting architectural concretes. Another object of the present invention is to provide a composition,

  especially varnish, likely to stick well even in a humid environment.

  Another object of the present invention is to provide a composition of the type

  previous that is quickly (at most two hours,) off dust.

  These and other objects which will appear later are achieved by means of a composition useful in particular for external 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 1 00 C. An isocyanate sub-composition already or to be emulsified in the same aqueous phase and in that said polyol has

minus two components.

  It is desirable for said polyol to be in the form of several dispersions in a continuous phase thus constituting several latices (particle population of the same composition). Let us 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 case of mixing, this constraint applies to at least one of the latexes, preferably

all.

  In the case of using high Tg latex, coatings are obtained

  rigid with high hardness, particularly suitable for industrial floors.

  For a better flexibility (in particular elongation at break) and a better resistance to the bad weather (rapid variation of the outside temperature in particular during a single nycthémère [cycle jouruit]), it is desirable that the polyol, or at least l one of the polyols, when there are several of them, has a tg of less than 0 ° C., advantageously of -10 ° C., preferably of -20 ° C., see -30 ° C. in very harsh countries; For a good adhesion to the support a tg (in case of mixing latex of at least one latex) at most equal to the application temperature (of the

  precursor composition of the coating on the support) .is advised.

  In order to produce paint or varnish films, a mixture of two dispersions is used in one (the same) continuous phase. These dispersions form two particle populations; One, the emulsion containing the isocyanate which can be blocked, and the other, a polyol dispersion. This mixture can be made by mixing a suspension and a dispersion, but more generally by dispersing a second component in the continuous phase of a first component. Most often the isocyanate is emulsified in the aqueous phase of the dispersion of the polyols. It is desirable that the polyol dispersions used in combination with these emulsions have average sizes measured by quasi-elastic light scattering of at least about 10 nm, preferably about 20 nm, preferably about 50 nm, and at most equal to about nanometers, preferably 150 nanometers and preferably at most nm. Obtaining polyol and in particular polyol latex with a variable glass transition temperature (high or low) can be achieved 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 with butyl acrylate makes it possible to significantly lower the

  glass transition temperature and to reach the values above.

  Advantageously, the polyol may comprise carboxylic or sulphonic ionic groups, but it may also contain no ionic group. In the context of the present invention, it has been shown that the presence of anionic carboxylate function (-CO2-) significantly increases the kinetics of drying, which is particularly advantageous for obtaining a fast "dust-free", especially when operates outside. A significant effect can be noted for a ratio of at least one carboxylic function to about 20 reactive hydrogen functions [alcohol or phenol function], preferably at a ratio of one to about 10, preferably at a ratio of one for about 5; however, it is desirable for this ratio to be (for the case of several polyols, on average and / or for the polyol which is the richest in terms of alcohol) at most equal to a function for a function, preferably of a carboxylic function for two ol functions. Countercations of carboxylates advantageously correspond to the same preferences as those

  expressed for countercation of the compound according to the present invention.

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

  in water or a latex-type dispersion.

  Thus one can consider various implementation of the present invention.

  According to a particularly advantageous embodiment of the present invention, said polyol is in the form of several latices (particle population of the same composition) of which at least one has a temperature

  vitreous transition (tg) at most equal to the application temperature.

  Thus, most often, it is desirable that said polyol is in the form of several latices (particle population of the same composition), at least one of which has a glass transition temperature (tg) at most equal to

  ambient temperature (approximately 20 C), advantageously at 1 0 C.

  According to an advantageous variant of the present invention, said polyol is in the form of several latices 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

  1/4, advantageously at 1/3, preferably at 2/5.

  To resist rigorous cold, according to an advantageous option of the present invention, the components of said polyol have a glass transition temperature (tg) at most equal to 0 C, advantageously to -10 C, of

  preferably at -20 ° C. or even -30 ° C.

  More precisely, it is recommended that said polyol be in the form of several latices of which at least one (or more) has a glass transition temperature (tg) at most equal to 0.degree. C., advantageously at -10.degree. -20 C, or at -30 C and represents (s) a mass fraction at

  less than 1/4, advantageously 1/3, preferably 2/5.

  According to an advantageous embodiment of the present invention, said polyol is formed of at least two latexes, at least one of which has a low hydroxyl content, the percentage by mass of low-hydroxyl latex being between closed) 10 and 90% and advantageously between 10 and 50%,

preferably between 10 and 40%.

  Advantageously, said polyol formed from at least two latexes, at least one of which has a glass transition temperature (tg) at least equal to C, advantageously at -10 ° C., preferably at -20 ° C. or even at -30 ° C. mass percentage of latex at low tg being between (closed range)

  and 90% and advantageously between 10 and 50%, preferably between 10 and 40%.

  The concepts above are detailed below.

  However, the preferred polyols for the invention are latices as described below. It seems possible to disperse a standard polyisocyanate in a water-soluble polyol under certain formulation conditions (in particular with a pigment-to-binder ratio of the suitable paint). However, the use of standard polyisocyanates with hydrodisperse 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 has been found through the use values of the coatings (in particular chemical resistance and hardness) that the crosslinking of

  films was much more important when the polyol used was carboxylated.

  In particular, latexes can advantageously be used, in particular nanolatex (that is to say latex whose particle size is nanometric [more precisely whose d50 is at most equal to about 100 nanometers]). In a particularly advantageous embodiment of the present invention, the polyol is advantageously a latex of nanometric size having the following characteristics: C> d50 (or more often average diameter) of between 15 and 60 nm, advantageously between 20 and 40 nm> solid content ( polyol, that is to say excluding isocyanate, filler [For example pigment] and adjuvant): between 10 and 50, advantageously between 25 and 40%

  C> a d80 less than 1 micrometer.

  as regards the following values, they relate to the case of the use of a polyol alone, otherwise they are average values:> carboxylate function of 0.5 to 5% in mass (COO- = 44): 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, the latices, especially when their glass transition point is below 0.degree. C., advantageously at -10.degree. C., preferably at -20.degree. C., make it possible to obtain, even with aromatic isocyanates of good quality, weather resistance and in particular temperature variations, particularly suitable for external coatings or coatings deposited on substrates already having cracks or likely to crack. It may be particularly interesting to adjust the flexibility of

  coatings playing on the Tg of the latex.

  Also a latex of high Tg, can make it possible to obtain coatings

  rigid having improved mechanical properties ...

  According to a particularly advantageous embodiment of the present invention, a mixture of polyol dispersions (latex mixture) comprising at least two polyols (two latices) or classes of polyols is used.

associated two by two.

  It is thus possible to associate with a latex (or several latexes) having a content (in percent by weight) in an OH function of at least 1% (about 0.3 miliq equivalent per gram), advantageously at 1 , 5%, preferably 2%, a latex (or more latex) B poor alcohol function (less than 1%,

  preferably 0.8%, preferably 0.5%).

  It is possible to associate a latex of greater than room temperature (approximately 20 ° C.) with a latex (which may advantageously be one of the above-mentioned latexes B) of less than room temperature, advantageously at 10 ° C., preferably at 0 ° C., more

  preferably with a tg between -1 0 C and -40 C.

  It is also possible to mix latexes of different particle sizes to

  improve the filling factor.

  These latices can be used simultaneously or successively. Thus, it is advantageous to form a precoat of latex of type B before using the composition formed of latex A and emulsified isocyanate according to the invention. The ratio between the latices can vary between 90/10 and 10/90, but it is preferable that the average OH content (mass = 17) is at least equal to a value of between 1 and 5, advantageously between 1.5. and 4, of

preferably between 2 and 3%.

  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 [particle-continuous phase interface (the

  more often aqueous) for latex].

  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 latices (not functionalized in isocyanate masked) described in the French patent application filed on April 28, 1995 n 95/05123 and in the reflex European patent application EP 0.739.961 give very good results for a better understanding from this passage we can refer to this text. Thus, advantageously, the latex particles have, on average, an acidic (advantageously carboxylic) content, accessible between 0.2 and 1.5, advantageously between 0.2 and 1.2 milliequivalents / gram of solid, and they exhibit on average, an accessible primary alcohol content of between 0.3 and 2 milliequivalents / gram,

advantageously between 0.3 and 1.5.

  Thus, as indicated in this document, the latexes consisting of particles carrying function (s) according to the invention are preferably hydrophobic and advantageously have a size (dgo90) generally of between 0.01 micrometer and 10 micrometers and preferably at most equal to 5 micrometers, or even 2 micrometers. They are calibrated, monodisperse and present in the latex in a quantity varying

  between 0.2 to 65% by weight of the total weight of the latex.

  The weight average molecular weight (Mw preferably determined by gel permeation chromatography, known by the acronym "GPC") of the polymers constituting the particles of the latex is advantageously

  between 5.104 and 5.106, greater than 1.105 and not more than 2.106.

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

  anhydride, acid chloride, amide, nitrile, etc.).

  The distribution between the different types of units advantageously corresponds to the following rules: The content of the unit derived from the monomer consisting of said free alcohol having an activated ethylenic function, and referred 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 unit is derived from an ester, an alpha ethylenic acid, with a diol whose alcohol function remains unesterified. Said diol is advantageously an omega / omega prime diol,

  advantageously chosen from butanediol-1,4, propane-1,3-diol and glycol.

  It is desirable that said alpha ethylenic acid is an acrylic acid

optionally substituted.

  According to a preferred embodiment of the present invention, the content of a unit derived from a free carboxylic acid (or in the form of a salt thereof), and referred to

  all the patterns of any kind, 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 a salt thereof. The particles resulting from the present invention may 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 [o a latex seed is covered by surface polymerization (epipolymerization, sometimes referred to as overpolymerization)] of a separate polymer. The heart is sometimes called germ by analogy to the phenomenon of crystallization. In this case, only the second polymer, that is to say the superficial polymer, meets the concentration constraints at different levels.

  functions according to the present invention.

  It is desirable that said isocyanate sub-composition is self-emulsifying (i.e., forms an emulsion under agitation).

  moderate eg agitation of Example 1).

  This character can be provided by the grafting of polyethylene oxide chain or preferably can be provided in the form of the compositions referred to in the international patent application published under the French patent.

WO97 / 31960.

  With respect to isocyanates proper, the following may 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 embodiment of the present invention, after dispersion or emulsion, the sum of the constituents of the binder (that is to say, the mass contents of the or isocyanates, emulsifiers and polyols), in water varies from 10, preferably from 30 to 70% by

  relative to the totality of the composition.

  The isocyanates targeted by the invention include, in particular, the compounds

detailed below.

  These compounds may 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 isocyanurate type, also called trimer, structures uretidine dione, also called dimer, biuret or allophanate structures or a combination of this type of structures on a single molecule or in mixture. If it is desired to strongly lower the solvent content of the composition, especially when it is in the form of an emulsion, it is preferable to use mixtures of this type naturally (that is to say without the addition of a solvent). low viscosity. The compounds having this property are especially the derivatives (isocyanurate type, also called trimer, structures uridine dione, also called dimer, biuret or allophanate structures or a combination of this type of structures on a single molecule or in mixture) in part and or all of the aliphatic isocyanates whose isocyanate functional groups are linked to the backbone via ethylene moieties (for example polymethylene diisocyanates, especially hexamethylene diisocyanate and those of arylenedialkoylediediisocyanates whose isocyanate function is distant from the

  aromatic rings of at least two carbons such as (OCN- [CH2] t-r- [CH2] u-

  NCO) with t and u greater than 1). These compounds or mixtures preferably have a viscosity of at most about 3000 centipoise (or millipascal.second), preferably about 1500 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 amount of appropriate solvent (s). As already mentioned above, the isocyanates

  concerned may be mono-, di- or even polyisocyanates.

  Advantageously, these derivatives may contain structures of the isocyanurate type, also called trimer, structures uridine dione, also called dimer, biuret or allophanate structures or a combination thereof.

  type of structures on a single molecule or in a mixture.

  The monomeric isocyanates may be: aliphatic, including cycloaliphatic and arylaliphatic, such as: * as simple aliphatic, polymethylene diisocyanates and especially hexamethylene diisocyanate; as partially "neopentyl" partially cyclic aliphatic (cycloaliphatic) isophorone diisocyanate (IPDI); as cyclic aliphatic (cycloaliphatic) diisocyanate those derived from norbornane;

  arylenedialkylidenediisocyanates (such as OCN-CH2-4-CH2-

  NCO, a part of which does not have an essential difference with aliphatics, namely those whose isocyanate function is distant from the aromatic rings of at least two carbons such as (OCN- [CH 2] t - ') [CH 2] u- NCO) with t and u greater than 1;

  or else aromatic such as toluylene diisocyanate.

  The preferred polyisocyanates contemplated 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, of the NCO functions are connected to a skeleton hydrocarbon, via a saturated carbon (sp 3), preferably with at least one, more preferably at

  at least two of the conditions below.

  At least one, advantageously two, 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 when the carbon carrier of the isocyanate function carried a hydrogen, preferably two hydrogens); at least one, advantageously two, of said saturated carbons (sp 3) are themselves borne by a carbon, advantageously aliphatic (that is to say hybridization sp3), itself carrying at least one, advantageously two, hydrogen (s); in other words, it was found that better results were obtained when the carbon carrying the isocyanate function was in the "neopentyl" position; All the carbons through which the isocyanate functions are connected to the hydrocarbon backbone, are saturated carbons (sp 3), which are advantageously partly, preferably entirely, carrying a hydrogen, preferably two hydrogens; in addition, it is advantageous for said saturated carbons (sp3) to be at least partly (advantageously one-third, preferably two-thirds), preferably in their entirety, themselves borne by a carbon, advantageously aliphatic (that is to say hybridization sp3), itself carrying at least one, advantageously two, hydrogen (s); in other words, it was found that better results were obtained when the carbon carrying the isocyanate function was in the "neopentyl" position; Particularly well suited are those which have at least partly an isocyanuric or biuret skeleton (whether this skeleton is derived from one or more monomers, see below) and more specifically from structures of the isocyanurate type, also called trimer, uretidinedione structures, also called dimer, biuret or allophanate structures or a

  combination of this type of structures on a single molecule or in a 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, NCO functions are connected to a hydrocarbon backbone, via saturated carbon (sp3); 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 when the carrier carbon of the isocyanate functional group carries a hydrogen, preferably two hydrogens; furthermore, it is advantageous for said saturated carbons (sp3) to be at least partly (advantageously one-third, preferably two-thirds), preferably in their entirety, themselves carried by a carbon, advantageously aliphatic (that is to say of hybridization sp3), itself carrying at least one, advantageously two, hydrogen (s), in other words it was found that better results were obtained when the carrier carbon of the isocyanate function was in the so-called "neopentyl" position. The isocyanates, especially aliphatic ones, react with some of the anionic compounds referred to.11 react with the hydroxyl of the fon Acidic acids not or badly neutralized. These compounds are also covered by this

invention.

  in the polyol (s) before the addition of the isocyanate.

  Another object of the present invention is to provide a method of application

  of the isocyanate-based composition to form a coating.

  These and other objects which will appear later are achieved by means of a process comprising the application of a preparation layer (that is to say of composition according to the invention comprising the aqueous phase and the constituents of the 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 at 50 μm (micrometer), preferably 100 μm (micrometer) and at most 1000 μm (micrometer), advantageously at 400 microns, preferably micrometers, corresponding after drying to a thickness between

and 80, even 200 micrometers.

  According to one advantageous embodiment, this process involves drying

  from 20 C to 60 C for a duration ranging from 1/4 to 24 hours.

  Advantageously, this drying takes place in the presence of a solvent to help

the elimination of water.

  According to a particularly advantageous implementation of the present

  the invention is carried out by spraying.

  Surface preparation is well known to those skilled in the art (eg, phosphating for ferrous steel compounds or chromating for aluminum-based surfaces). (We can for example refer to the following works: "organic coating technology" volume II of H. F. PAYNE and "Paint

  Handbook "Edited by G.E.WEISMANTEL).

  In the particular case of concrete and stone substrates, treatment will be carried out to remove deposits or residues likely to reduce adhesion (laitance, dust, waxes, curing compounds, organic soils).

  by mechanical treatment (brushing, grinding, sanding, ...).

  According to the present invention, it is thus possible to obtain coatings (in particular paints or varnishes) having the technical characteristics (these values depend mainly on the polyols used): implementation and characteristics of the coating dry thickness Iso2178: 45 prm support and Treatment of the latter: phosphated-treated steel: R461 plates from supplier Q Pannel minimum properties usual obtained test din 67530 (these values are only of interest when it is desired to paint glossy but not when one wants to the matt or satin paint) Brillance 200 0,5 80

  0.5 90

  hardness Konig iso 1522 l10s 150s Adhesion test din 53151 GT-5 GT-1 Shock resistance test 10 cm> 100 cm N iso 6272 direct reverse 5cm> 100 cm Resistance to methyl-20> 200 ethyl ketone (butanone) (Double pass) Outdoor resistance QUV 50 h 800 h Din 53384 Rhodafac RE610 is a mixture of mono- and phosphoric diesters according to formula ll, the average formula of its hydrocarbon radical is a polyethoxylated nonylphenol (-dix laws). The molar ratio

  between mono ester and diester is about 1 (mathematical rounding).

  Example 1 - preparation of the 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

  mono- and phosphoric di-esters according to formula 11) and 3 g of triethylamine.

  This mixture is stirred using a frame or deflocculating blade for minutes at 100 revolutions / minute. This mixture has a viscosity of 0.84 Pa.s. At 20 0C

  and a coloring less than 100 APHA.

  EXAMPLE 2 Preparation of the mixture 2 79 g of tolonate HDT (trimer-based isocyanurate oligomer) are mixed with 10 g of butyl acetate and 9 g of Rhodafac RE610 (mixture of

  mono- and phosphoric diester according to formula 11) and 1.4 g of triethylamine.

  This mixture is stirred with a paddle or deflocculating blade for 5 minutes.

minutes at 100 rpm.

  EXAMPLE 3 - Nanolatex 1 The nanolatex used is an experimental product produced according to the process described in the French patent application filed on April 28, 1995 No. 95/05123 and in the European Patent Ref N EP 0,739,961 following: average diameter 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 Mass molecular weight 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. (40 ° C. to 50 ° C.) Example 4 - Pre-treatment of a coating From the mixture 1 and the Nanolatex 1 The varnish is prepared by incorporation with manual mixing of 4. 6 g of the mixture 1 in 45.6 g of nanolatex. This ratio corresponds to a ratio of

NCO / OH functions of 1.2.

  The mixture thus prepared has a 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 properties such as the resistance solvent, 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 the 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 with 55% relative humidity. Achieving a short drying time and a relatively long shelf life of the mixture is a much sought after advantage by

painting.

  The use values of the coating are also generally of a very good level, which may be mentioned: the Persoz hardness of the film of 50 μm dry measured on a steel plate after drying for 24 hours at 23 ° C. and 55% relative humidity is 275 seconds, - the gloss at a 20 C angle of the film applied to a 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 soaked cotton, - acid resistance (sulfuric 20%, nitric 10%, hydrochloric acid 10%) is very good, - resistance to alcohols (ethanol) and hydrocarbons ( diesel) is also good,

  - The average base resistance (ammonia 20%) is satisfactory.

  These excellent performances of this Nanolatex-

  polyisocyanate according to the invention are certainly attributable to the physicochemistry very particular of these products in particular the very large surface area of the nanolatex which promotes a high homogeneity crosslinking

in the final polymer.

  Example 5 - Application on a 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 provides a water repellency of the support which results in a beading effect, and less water absorption. In addition, the coating has good abrasion resistance. Exemole 6 - Nanolatex 2 Nanolatex is an experimental product described in the French patent application filed on April 28, 1995 n 95/05123 and in European Patent Ref N EP 0,739,961 with the following characteristic: ds0 about 35 Carboxyl function: 1% by weight on the dry functional polymer ol: 2.6% by weight on the dry polymer Molecular weight greater than 100% Dry extract by weight: 30% pH about 8 Glass transition temperature about -30 C Example 7 - Preparation of a coating from mixture 1 and nanolatex 2 The varnish is prepared by incorporation with manual mixing of 4.6 g of mixture 1 in 45.6 g of nanolatex. This ratio corresponds to a ratio of

NCO / OH functions of 1.2.

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

  cause of large temperature variation).

  Moreover, the crosslinking with the polyisocyanate according to the invention gives the

  coating excellent resistance to chemicals and 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 freeze-thaw cycle resistance, namely: two hours at 60 ° C. with UV radiation and lower relative humidity

at 50%;

  two hours at -200C; two hours at 20 C with liquid water over the entire coated surface; two hours at -20 ° C; c two hours at 60 ° C with UV radiation and lower relative humidity

at 50%;

  two hours at 23 C with relative humidity greater than 95%.

  the behavior is also good when submitting to the NF cycle:

XPP1 8420

  EXAMPLE 8 Nanolatex 3 Nanolatex is an experimental product described in the French patent application filed on April 28, 1995 No. 95/05123 and in the European Patent Ref N EP 0 0 739 961 of the following characteristics: average diameter 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 weight greater than 100,000 Dry extract by weight: 30% pH about 8 Minimum temperature of film formation about 0 C Glass transition temperature about 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-phase stirrer)

for 5 minutes.

  EXAMPLE N 10 - Mixture of Nanolatex 50 g of nanolatex 1 (described in Example 3) are mixed with 50 g of nanolatex 3 (described in Example 8), with gentle stirring (three-phase stirrer)

for 5 minutes.

  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-phase stirrer) for 10 minutes. 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 on a Fibrocement support using a spray gun

  pneumatic at a rate of about 200 g / m2.

  Example 12 - Preparation and Application of a Coating from Mixture 2 and the Nanolatex Mixture of Example 9 The resin was prepared by incorporating 9.75 g of the mixture 2 into g of the nanolatex mixture of Example 13 with moderate stirring (three-phase stirrer) for 10 minutes. The mixture thus prepared has a pot life of at least

4 hours.

  The coating is applied on a Fibrocement support using a spray gun

  pneumatic at a rate of about 200 g / m2.

  Example 13 - Preparation and Application of a Coating from Mixture 2 and the Nanolatex Mixture of the Example 10 The resin was prepared by incorporating 6.5 g of the mixture 2 into 100 g of the nanolatex mixture of the example 14 with moderate agitation (stirrer

tripale) for 10 minutes.

  The mixture thus prepared has a pot life of at least

4 hours.

  The coating is applied on a Fibrocement support using a spray gun

  pneumatic at a rate of about 200 g / m2.

  Comparison of the results: Adhesion of the coating on the support Fibrocement (support with closed pores) The adhesion of the coating on the support Fibrociment was characterized by

  a grid test according to ISO 2409.

  Two tests were carried out on each coating: - adhesion after air conditioning for 7 days at room temperature, - adhesion after conditioning in air for 7 days at room temperature then

  immersion 7 days in water at room temperature.

  The results are reported in the following table: Example 11 Example 12 Example 13 polyol with a high content of 100% -75% -50%

% 75% -50%

  alcohol function and tn-40 C low poly content 0% 25% -50% alcohol function and tn- 15 C dry adhesion Gt-3 Gt-1 Gt-1 Adhesion after immersion Gt-5 Gt-2 Gt-4 -5 Comments the coating is tearing off of tearing off the broadband realization of during the incisions fast peeling off the adhesive tape

  The coatings are all good dry.

  However, those containing a bimodal mixture of polyols (two levels of

  ol function content) are better in dry adhesion.

  In wet adhesion, the compound based on a single latex is particularly poor, for the others an optimum is observed as a function of

low hydroxyl latex level.

  the mechanical properties are not affected by soaking and

  exhibits good reversibility by drying.

Claims (17)

  1. Composition useful in particular for external 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 in that said polyol has at least two components.   2. Composition according to Claim 1, characterized in that the said polyol is in the form of several dispersions in the same continuous phase.   constituting several latices (particle population of the same composition).   3. Composition according to claims 1 and 2, characterized in that said   polyol is in the form of several latices (particle population of the same composition) of which at least one has a temperature of   vitreous transition (tg) at most equal to the application temperature.   4. Composition according to claims 1 to 3, characterized in that said   polyol is in the form of several latexes (particle population of the same composition) of which at least one has a glass transition temperature (tg) at most equal to the ambient temperature (about  C), advantageously at 10 C.   5. Composition according to claims 1 to 4, characterized in that said   polyol is in the form of several latices 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 (s) a mass fraction at least equal to 1/4, advantageously at 1/3, preferably at 2/5.   6. Composition for resisting rigorous cold according to claims 1 to   , characterized in that said polyol is in the form of several latices of which at least one (or more) has a glass transition temperature (tg) at most equal to 0 ° C., advantageously at -10 ° C., preferably at -10 ° C. 20 ° C., 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 resisting rigorous cold according to claims 1 to   6, characterized in that the components of said polyol have a glass transition temperature (tg) at most equal to 0 C,   advantageously at -10 ° C., preferably at -20 ° C., or even at -30 ° C.   8. Composition according to claims 1 to 7, characterized in that said   polyol is formed from at least two latexes, at least one of which has a low hydroxyl content, the mass percentage of low-hydroxyl latex being between (closed range) 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 said   polyol formed from at least two latexes, at least one of which has a glass transition temperature (tg) of at least 20 ° C., advantageously at -10 ° C., preferably at -20 ° C. or even at -30 ° C. mass of latex at low tg is between (closed range) 10 and 90% and preferably between 10 and 50%, preferably between and 40%.   10. Composition according to claims 1 to 9, characterized in that   said isocyanate sub-composition is self-emulsifying (i.e., it forms an emulsion with moderate agitation, for example agitation of Example 1).   11. Use of the composition according to claims 1 to 10, characterized   in that for the formation of a coating on a support of variable porosity. 12. Use according to claim 11, characterized in that said support is selected from, non-metallic surfaces, facade coatings,   mortar and plaster and so-called phosphomagnesian materials.   13. Use according to claim 12, characterized in that said support is closed porosity.   14. Use according to claim 13, characterized in that said support is of variable inclination.   15. Process for preparing a coating according to claim 14, characterized in that it comprises the application of a layer of   Composition according to Claims 1 to 10, between 20 and 200   micrometers (measured on a dry basis) 16. The method of claim 15, characterized in that it comprises a   drying from 10 ° C. to 50 ° C. for 1/4 and 3 hours.   17. Process according to claims 15 and 16, characterized in that   comprises drying in the presence of a solvent to assist in the removal of Water.   i18. Coating obtainable by a process according to claims 15 to 17.