MXPA06009965A - Polymer aqueous dispersion for a barrier coating - Google Patents

Abstract

The invention relates to a polymer aqueous dispersion obtainable from a monomer mixture comprising by weight a) 100 parts of at least one type of ethylenically unsaturated monomer devoid of an ionic group, b) from 0.5 to 15 parts at least one type of ethylenically unsaturated monomer carrier of at least one carboxylic and/or carboxylic anhydride function, c) at least one type of ethylenically unsaturated monomer carrier of at least one second functionality selected from:phosphate, phosphonate, phosphinate in a such quantity that a ratio c/(b+c) ranges from 0,05 to 0,4, d) from 0 to 2 parts of at least one type of ethylenically unsaturated monomer carrier of at least one alcoxysilane function, e) from 0 to 5 parts of at least one type of ethylenically unsaturated monomer carrier of at least one active carbonyl function or other reactive function with an aldehyde function such as ureido or morpholine, imidazoline, oxazolodine and aziridine derivative or an amine function and f) from 0 to 10 parts, preferably from 2 to 8, of at least one type of ethylenically unsaturated monomer carrier of at least one function selected from hydroxy and primary or secondary amine. A preparation method, a coating composition comprising said dispersion and the use thereof in the form of coatings for metal or plastic substrates, in particular anticorrosive coatings for metal substrate are also disclosed.

Description

AQUEOUS POLYMER DISPERSION FOR BARRIER COATING DESCRIPTION Background and field of the invention The present invention relates to aqueous dispersions of polymer, the polymer preferably is of the styrene-acrylic type, for the preparation of hydrophobic coatings for metal substrates or plastics that protect by a barrier effect; the coating, whose formulation exhibits satisfactory stability, forms a barrier against the diffusion of corrosive agents and for protection against chemical and / or mechanical attacks, characterized by a long-lasting adhesion. The increasingly restrictive regulations regarding the use of volatile organic solvents and the concern to produce coating that do not affect the general environment are resulting in the largest use of coating compositions based on aqueous dispersions of polymers. Furthermore, the protection of substrates as varied as metals or plastics requires the use of coatings based on dispersions which show in particular an excellent compromise between performance in terms of adhesion, chemical and mechanical resistance and, more particularly in the case of metal coatings, of a high resistance to corrosion. Several solutions are already known in the state of the art and more particularly in the field of aqueous polymer dispersions for aqueous coatings for the protection of metal substrates. However, these coatings do not achieve the desired performance and achieved by the present invention. EP 221 498 discloses the use of corrosion inhibitor coatings of aqueous dispersions of polymers with or without a reduced level of surfactants through the introduction of a copolymerizable alkyl phosphate comonomer. Such a dispersion does not contain specific functional monomers, such as those of the present invention necessary to achieve a satisfactory compromise in operation, in particular in terms of the quality of dispersion or adhesion of the pigment. Finally, EP 1 193 298 discloses aqueous dispersions of polymers for glossy corrosion inhibitor coatings in the presence of strong acid monomers, the strong acid represents more than 45% by weight of the total acids. However, the coatings obtained are inadequate in particular as regards the salt spray resistance and the stability of the coating formulation.

However, none of these state of the art documents provides a satisfactory solution to the problem of protection by pigmented or colorless coatings of substrates as varied as metals and plastics while exhibiting an excellent compromise in operation in terms of the stability of the formulation of the coating, in particular, the stability of the pigment dispersion, the barrier effect for mechanical and / or chemical protection and adhesion. The present invention overcomes the inadequacies and disadvantages of the coatings of the state of the art by providing, as the core of the present invention, a specific aqueous dispersion of polymer for coatings for mechanical and / or chemical protection for substrates as varied as metals and plastics with A better compromise in operation during use. Thus, the specific aqueous polymer dispersion according to the present invention is particularly suitable for the preparation of pigmented or colorless coatings of a hydrophobic nature for mechanical and / or chemical protection which satisfactorily solves the following needs and requirements: - a good barrier effect against water and corrosive agents, - good chemical resistance to agents such as acids and bases, mineral oils, vegetables and fats, including fuels and organic solvents, a good profile of mechanical properties, characterized by a good compromise of hardness / flexibility, good adhesion to various substrates, more particularly to metals, after exposure to severe conditions, in particular exposure to moisture and corrosive environments, adhesion gives them long-lasting protection, - in the case of application to metal substrates an inhibitory effect of the oxidation, and, finally, good stability of the coating formulation as formulated for the application. The first principal subject of the present invention is a specific aqueous dispersion of polymer in the composition and proportions of the monomers and other components involved. This dispersion can be crosslinkable according to its composition during the smoke stage. A second main subject of the invention is a process for the preparation of the dispersion. Another principal material according to the invention is a coating composition comprising at least one aqueous polymer dispersion according to the invention.

An additional material according to the invention is the use of dispersions in coating compositions for the protection of metal and / or plastic substrates. Finally, the final subject of the invention is such substrates coated by at least one coating composition as defined according to the invention. The first subject of the invention is an aqueous dispersion of polymer obtainable from a mixture of monomers comprising, by weight: a) 100 parts of at least one ethylenically unsaturated monomer not comprising an ionic group; b) from 0.5 to 15, preferably 1 to 10, preferably 2 to 8 and preferably still 2 to 7 parts of at least one ethylenically unsaturated monomer bearing at least one carboxylic anhydride and / or carboxyl functional group; c) at least one ethylenically unsaturated monomer carrying at least one second functionality selected from: phosphate, phosphonate or phosphinate, in an amount such that the quotient c / (b + c) ranges from 0.05 to 0.4, preferably from 0.1 to 0.4 and preferably from 0.1 to 0.25; d) from 0 to 2, preferably 0.05 to 1.5 parts, of at least one ethylenically unsaturated monomer bearing at least one alkoxysilane functional group; e) from 0 to 5 parts of at least one ethylenically unsaturated monomer carrying at least one active carbonyl functional group or any other functional group which reacts with an aldehyde functional group, such as a ureido, morpholine, imidazoline derivative, oxazolidine, aziridine or an amine functional group; f) from 0 to 10, preferably 2 to 8 parts, of at least one ethylenically unsaturated monomer carrying at least one functional group selected from hydroxyl and primary or secondary amine or carrying a precursor group of such a functional group. The ethylenically unsaturated monomer type a) does not comprise an ionic group, it is generally possible to choose monomers having a hydrophobic nature and more particularly: styrene and its derivatives comprising vinyltoluenes (ortho-, meta- or para-), -methylstyrene, tert-butylstyrene, para-butylstyrene, para-decylstyrene, (meth) acrylic esters of alcohol of 1 to 18 carbon atoms, acrylonitrile and vinyl esters, such as those of versatic acid. They are preferably selected from: styrene and its derivatives, methyl (meth) acrylate, butyl methacrylate, more particularly n-iso-tert-butyl (meth) acrylate, 2-ethylhexyl acrylate and acrylonitrile. As examples of ethylenically unsaturated monomers type b) carrying at least one carboxyl and / or carboxylic anhydride functional group, there may be mentioned: (meth) acrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, isocrotonic acid and acid vinylbenzoic acid and preferably (meth) acrylic acid, maleic acid, fumaric acid or itaconic acid and their anhydrides. The ethylenically unsaturated monomer type c) carrying at least one second functionality can be a carrier of a functional group of the phosphate type, according to the general formula below: or phosphonate type Kl O 'i II R-C-P (0") 2 nKX, mKX- or phosphinate type in which - R is an organic radical comprising an ethylenically unsaturated organic group, which may be a group (meth) ) acrylic, vinyl or allyl The organic radical R can also comprise in its structure a polyalkoxylated chain comprising alkoxy units selected from oxyethylene (OE) and / or oxypropylene (OP), preferably oxyethylene (OE) and with a number of alkoxy units ranging from 1 to 30, preferably from 1 to 10, - Ri and R2 can be H or alkyl of 1 to 2 carbon atoms, and K1 + and K2 + are an H + or an alkaline earth metal cation and ym are each equal to 0 , 1 or 2, such that n + m = 2. More particular monomers of type c) can be selected from alkyl and alkoxylated alkyl (meth) acrylates bearing a terminal phosphate group, which is preferably a monoester / diester mixture with a predominance of monoester, with the nature and number of alkoxy units as defined above for the case of the radical R, a mono-ester of alkyl phosphate (meth) acrylate, preferably ethyl methacrylate phosphate, polyoxyalkylene (meth) acrylates, preferably the phosphoric monoester 2- (methacryloxy) ethyl and (methacryloxy) polyoxyethylene phosphoric monoester with 1 to 10 ethoxy units. The aqueous dispersion composition may comprise up to 2, preferably 0.1 to 1.5 parts, per 100 parts of a) of at least one ethylenically unsaturated monomer d) carrying at least one hydrolysable alkoxysilane functional group. This monomer is added during the polymerization and is selected from methacryloxy-silanated derivatives, such as α-methacryloxypropyltrimethoxysilane or triisopropoxysilane or -triethoxysilane. The aqueous dispersion according to the invention can be crosslinkable by means of favored selective reactions during the passage of film formation. In such a case, it may also comprise 0 to 5 parts by weight of at least one polyfunctional compound bearing at least 2 functional groups hydrazide or amine or aldehyde or a precursor group of such functional group, these are added after the dispersion is has prepared by emulsion polymerization. Such a hydrazide-type compound can be obtained by reaction of a polycarboxylic acid with hydrazine and is preferably of the bishydrachid type of adipic acid. Also, the aqueous dispersion composition may optionally further comprise at least one compound e) carrying at least one active carbonyl functional group or any other reactive aldehyde functional group, such as a ureido derivative, morpholine, imidazoline, oxazolidine, aziridine or an amine functional group. The active carbonyl functional group is defined as a non-enolyl or aldehyde type ketone carbonyl functional group, such as is present in (meth) acrolein, methylvinylketone and diacetone acrylamide, or of the enolic type as in acetoacetoxyalkyl (meth) acrylates or (meth) ) acrylamides or acetoacetamidoalkyl (meth) acrylates or (meth) acrylamides, such as for example acetoacetoxyethyl (meth) acrylate and acetoacetoxyamidoethyl methacrylate. The compound of type e) carries an active carbonyl functional group or other functional group which reacts with a functional group aldehyde preferably chosen from diacetone acrylamide (DAAM) and acetoacetoxyethyl methacrylate (AAEMA). Functional groups that react with an aldehyde functional group are defined in US 2004/0198 0A1 in paragraph 11. Compounds of type e) comprise, in addition to the AAEMA-type compounds, derivatives of the ureido type, such as methacrylate 2. ethylene or 2-ureidoethyl (meth) acrylate, or other morpholine derivatives, such as N- [2- (meth) acryloxy) ethyl] morpholin-2-one, imidazoline derivatives, such as 2-methyl-l -vinyl-2-imidazoline, oxazolidine derivatives, such as 2-3-oxazolidinyl ethyl (meth) acrylate, aziridine or an amine functional group, such as dimethylaminoethyl methacrylate (DAMAME). The presence of the compound e) carrying at least one active carbonyl functional group or another functional group which reacts with an aldehyde functional group, in a composition already comprising the polyfunctional compound mentioned above, may contribute to the adhesion properties of the film on some substrates. This can also lead to a reaction with a polyfunctional compound soluble or dispersible in water: carrying at least two hydrazide or amine or aldehyde functional groups or a precursor group of such functional group, which can react with an active carbonyl functional group if the The latter is defined as a ketone or non-enol carbonyl functional group; or carrying at least two hydrazide or amine functional groups or a precursor group of such functional group, which can react with. an active carbonyl functional group if the latter is defined as an enolic type carbonyl functional group; or carrying at least two aldehyde functional groups or a precursor group of such functional group, which may react with an optional reactive functional group, such as a ureido derivative or a morpholine derivative, imidazoline, oxazolidine or aziridine or an amine functional group, whose water soluble or dispersible compound will be added to the polymer dispersion during or after the polymerization. This favored reaction during the smoke step, will produce polymers of the crosslinking dispersion, thus improving the mechanical and guímica resistance and the protective properties of the coating. The hydrazide type compound can be obtained by reacting a polycarboxylic acid with hydrazine and is preferably of the adipic acid bishidrazide type. Also, the presence in the monomer mixture of the dispersion of an ethylenically unsaturated monomer f) carrying a hydroxyl functional group or a primary or secondary amine functional group or a precursor group of such a functional group makes it possible to cross-link the coating film during drying by addition of other functional reactive compounds of polyisocyanate, melamine-formaldehyde resin, (poly) epoxy or polyfunctional alkoxysilane type, such as an epoxyalkoxysilane. The external crosslinking can also be introduced by a polyaziridine or a carbodiimide which also reacts with the carboxyl groups present in the polymer in dispersion. These coreactive compounds are generally introduced into the coating composition during their preparation or immediately before use. Among the preferred ethylenically unsaturated monomers, there may be mentioned tert-butylaminoethyl methacrylate (TBAEMA) and hydroxyalkyl (meth) aerials, preferably with alkyl of 2 to 4 carbon atoms, such as 2-hydroxyethyl methacrylate (HEMA). The alkoxylan additives comprise at least one hydrolyzable group Si-O-C and a group Si-O-X, wherein X carries an organic group which reacts with a functional group present in the dispersion polymer, preferably an epoxy or amino group. Among the epoxysilanes, there must be mentioned α-glycidoxypropyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and, among the aminosilanes, bis [γ- (trimethoxysilyl) propyl] amine, [N- (ß-aminoethyl) -α-aminopropyl] methyldimethoxysilane , [N-phenyl-α-aminopropyl] trimethoxysilane, (α-aminopropyl) trimethoxysilane, aqueous solutions of 'aminoalkylsilicone, (α-aminopropyl) trimethoxysilane, trimethoxysilane of [N- (β-aminoethyl) -α-aminopropyl] or organofunctional triaminosilane . These additives can be added either after the polymerization and cooling of the dispersion or during the preparation of the coating composition. The polymerization of the aqueous dispersion can be carried out according to a semi-continuous emulsion process known to those of ordinary skill in the art. The different raw materials present in the composition, such as at least one standard radical polymerization initiator and at least one surfactant, are also involved during the reaction. The surfactant may be of the anionic or nonionic type or of a combination of at least one anionic surfactant and at least one nonionic surfactant. It is preferably present at a total level ranging from 0.5 to 5 and preferably from 1 to 3 parts per 100 parts of a). The surfactant may include α, β-ethylenic unsaturation which makes it copolymerizable with monomers a), b), c), d), e) and f). The anionic surfactants are selected from sulfates, ether sulfates, sulfonates or phosphates of alkoxylated fatty alcohols. Also, nonionic surfactants are selected from ethoxylated fatty alcohols, ethoxylated derivatives of alkylphenols and ethylene oxide / propylene oxide copolymers. The surfactants may also be a combination of at least one anionic surfactant and at least one nonionic surfactant as described above. The preferred anionic surfactants are chosen from alkoxylated alkyl phosphates wherein the alkoxy units are of the ethoxy and / or propoxy type with the following typical structure: the group R 'may be the alkyl residue of a fatty alcohol which may include α, β-ethylenic unsaturation with a chain which may be linear or branched. It comprises a hydrocarbon chain distribution for which the number of coals can vary from 8 to 18. R 'is preferably the residue of a saturated fatty alcohol having a number of coals ranging from 12 to 14. Preferred surfactants are of the type alkylpolyether ester phosphate alkoxylated with R 'as 12, 13 or 14 carbon atoms, the alkoxy being an oxyethylene. The R 'group may also be a derivative of the ethoxylated alkylphenol type, generally nonylphenol or octylphenol ethoxylated. The group consisting of alkoxy units can be either polyoxyethylene type (x units), polyoxypropylene type (y units) or a copolymer comprising a polyoxyethylene block and a polyoxypropylene block, such as Pluronic two-block surfactants or three blocks sold by BASF, where: x is between 0 and 50; and it is between 0 and 50; y / (x + y) is between 0 and 1.

The level of the surfactant in the composition of the dispersion can vary from 0.5 to 5 parts by weight per 100 parts of a) and preferably from 1 to 3 parts by weight. The particle size of the dispersion is determined, inter alia. Within this range of levels, the particle size ranges from 50 to 200 nm, preferably from 70 to 200 nm and more preferably from 80 to 120 nm. The degree of neutralization of the two acid functional groups of the phosphate group of the surfactants is adjusted before and during the synthesis by controlling the pH. The polymerizations are preferably carried out between pH = 2.5 and, so that at least one of the acid functional groups of the phosphate group is partially neutralized. The agent for neutralizing the phosphate functional groups is a base chosen from potassium hydroxide, sodium hydroxide, ammonium hydroxide, potassium carbonate, sodium carbonate, ammonium carbonate, potassium hydrogen carbonate, sodium hydrogencarbonate, ammonium hydrogencarbonate, amines or amines of alcohol. Preferred bases are volatile amines, such as ammonia or neutralizing agents that decompose without leaving inorganic residues that are sensitive to water after the drying step of the paint film, such as ammonium carbonate. Polymerization initiators are radical polymerization initiators that are preferably water soluble, such as sodium persulfate, potassium persulfate or ammonium persulfate, used singly or in the presence of reducing agents, such as sodium metabisulfite, sodium dithionite, sodium thiosulfate, sodium formaldehyde sulfoxylate, a mixture of disodium salt of 2-hydroxy-2-sulfinacetic acid, sodium sulfite and disodium salt of 2-hydroxy-2-sulfoacetic acid or of a mixture of disodium salt of hydroxysulfinacetic acid and of disodium salt of hydroxysulfoacetic acid, sold respectively under the trade names of golite® FF6 and golite® FF7 by Brüggemann. The soluble or partially fat soluble radical polymerization initiators can also be used. These initiators will include peroxides or hydroperoxides and azobisisobutyronitrile derivatives. The peroxides or hydroperoxides are used in conjunction with the reducing agents described above, to lower their activation temperature. According to an alternative form of the invention, the dispersion comprises at least 2 different polymers with various glass transition temperatures Tg: - either in the form of mixtures of particles of different polymers, - or in the form of composite structured particles of at least 2 phases of different polymers. According to another preferred alternating form of the dispersion, still according to the invention, the particles of the polymer dispersion are structured according to a core / shell structure and with at least one of the monomers b) or c) or d) or e) or f) is present predominantly in one of the phases. A) Yes, can be found predominantly in the shell or in the core of the particle, depending on the function and the final applications desired. Another specific possibility according to the invention is a dispersion that can be obtained: either by mixing at least 2 polymer dispersions with different functionalities and a different Tg, - or in the case of structured particles, by means of a polymerization process comprising at least two successive stages with different monomer compositions. The second main object of the invention relates to a specific preparation process for the aqueous dispersion according to the invention as defined above. In general, this dispersion can be obtained according to a semicontinuous emulsion polymerization process at temperatures that can vary between 60 and 90 ° C, and preferably between 65 ° C and 85 ° C. More particularly, the dispersion according to the invention can be obtained by a specific process which can comprise at least the following steps: i) polymerization of at least one monomer composition as defined according to the invention, ii) optionally, mixing At least two aqueous dispersions obtained according to step i), each of these dispersions comprises polymers with a different Tg. Another alternative form of the specific preparation process comprises at least the following steps: i) polymerization in at least one step of a monomer composition as defined according to the invention, ii) polymerization in at least one step of at least one second monomer composition as defined according to the invention, it being possible for this second composition to give a polymer with a different Tg value from that of step i) and / or to comprise at least one of the monomers b) or c) or d) or e) or f) in a predominant proportion in one of the monomer compositions. During a first step, the nucleation of the polymer particles can be carried out in situ carrying out the batch introduction of a small proportion of the monomers used for the entire process and of a sufficient quantity of a radical initiator or of a seed prepared in advance. . It is also possible to directly initiate the second stage without going through a nucleation step. The second step consists in running a monomer solution or a preemulsion of monomers and a radical initiator solution in a semicontinuous manner. This second stage can also be subdivided into several sub-stages while the reaction medium is fed with a monomer mixture. The composition of the latter may vary depending on whether the aim is to vary the glass transition temperature of the final composition, optimize the distribution of the functional monomers, such as the monomers of strong and weak acids already described and the crosslinking monomers, such as the ethylenically unsaturated monomers bearing alkoxysilane groups, the unsaturated monomers possessing an active carbonyl such as diacetone acrylamide, or the unsaturated hydroxylated or amine monomers, or to obtain a low smoke temperature of the latex to reduce the level of the coalescent agent in the formulation. Thus, during the polymerization of the emulsion, a fume-generating temperature of the latex of less than 20 ° C can be obtained by successively feeding at least two mixtures of monomers A and B having different values of Tg specifically TgA and TgB corresponding to the following characteristics: -50 ° C <; TgA < 30 ° C. -40 ° C < TgB < 130 ° C. where A represents between 45 and 90% of the total monomer composition and B represents between 10 and 55% of the total monomer composition. A can be fed before B or vice versa, depending on the desired particle structure. Also, to obtain the best compromise between hydrophobicity or water resistance and the ability to formulate typical formulations for corrosion inhibition applications, it may be advantageous to optimize the efficiency of the functional monomers. Thus, it is possible to choose to introduce the crosslinking monomers, such as diacetone acrylamide or the silanes at the beginning of the run of the monomers to concentrate them in the core of the particles. On the other hand, to ensure good dispersion of the pigment, it may be advantageous to introduce these monomers at the end of the monomer feed, to concentrate them on the surface of the particles. The third stage of the process is related to the reduction of residual monomers in the final composition. This is achieved by semicontinuously feeding in several solutions of radical initiators in the presence or absence of the activator which are reducing agents as described above. The reaction mixture is subsequently cooled during the final stage of the process. When it reaches a temperature below 40 ° C, it is neutralized at pH > 7 using a neutralization agent. The neutralizing agent is a chosen base of potassium hydroxide, sodium hydroxide, ammonium hydroxide, amines or alcoholic amines. Preferred bases are volatile amines, such as monoethylamine, triethylamine and, preferably, ammonia. After cooling, the hydrazide, amine, aldehyde or alkoxysilane type additives are also added, if appropriate. These additives are introduced according to a specific process: this is because they are emulsified beforehand in water by virtue of a surfactant system analogous to that used during the polymerization.

Another object of the invention is a coating composition comprising at least one aqueous dispersion according to the invention. This composition can be pigmented or non-pigmented of primer and / or surface finish, comprising the dispersion of the invention. This coating is a protective coating for metal or plastic substrates or an adhesion primer (or primer) or a corrosion inhibitor or primer (or primer) or a corrosion-inhibiting paint coating. More particularly, the coating is a coating that can be applied to at least one coating and preferably a pigmented coating. The coating can be formulated from a single component dispersion as defined by the invention. Thus, in some cases, ethylenically unsaturated monomers bearing at least one active carbonyl functional group and more particularly diacetone acrylamide or acetoacetoxyethyl methacrylate monomers can crosslink with compounds of the bishidracide and / or diamine type and / or bisaldehyde of adipic acid that are also present in the latex. Also, during its preparation, the coating composition can also form the object of the addition of polyisocyanate, melamine, epoxysilane, aminosilane, epoxy, polyaziridine or carbodiimide-type compounds capable of crosslinking with the functional monomer groups of type f) introduced in advance during the synthesis of the dispersion and chosen from ethylenically unsaturated hydroxylated or aminated monomers, such as hydroxyalkyl (meth) acrylates of 2 to 4 carbon atoms, preferably 2-hydroxyethyl methacrylate (HEMA) and tert-butylaminoethyl methacrylate (TBAEMA), or with the carboxyl groups of the monomers of type b), the residual carboxyl groups according to b) are, in this case, in proportions such that the. essential conditions of the invention relating to components b), c) and the relationship c / b + c continues to be respected. The reactions are then preferably of the unsaturated aminated / carbodiimide monomer type, hydroxylated / melamine unsaturated monomer or polyisocyanate. A further object of the invention is the use of the dispersion of the invention, as a protective coating for metal or plastic substrates or adhesion primer or corrosion inhibitor primer or corrosion inhibitor paint primer and preferably as a coating for corrosion inhibitor protection of metal substrates. The coating on metal or plastic substrates can be applied in one or more layers and can be pigmented or non-pigmented. The thickness of a coating layer can generally vary from 10 to 150 microns and preferably from 20 to 120 microns, when dry. According to another specific possibility of the invention, the coating composition comprises the dispersion which is obtained from a mixture of monomers as defined according to the invention and which further comprises up to 10 parts by weight of at least one ethylenically unsaturated monomer. functional saturated as defined in accordance with f) and so that it further comprises a compound that reacts with the functional groups of functional monomer f). A particular case of a non-pigmented coating is a lacquer for protecting plastics, with good adhesion and gloss properties. A final object of the present invention is a metallic or plastic substrate coated with at least one layer of at least one coating composition as defined according to the invention. This is because, with the prospect of ever more restrictive regulations in the field of VOC emissions, the development of aqueous technology is experiencing increasing success in the coating of metal and plastics. Thus, the dispersions, in particular of the styrene-acrylic type, according to the invention are used in pigmented or non-pigmented coating compositions which can be applied in at least one layer, preferably either two or three or even up to four layers of 10 to 150 μm per layer, when dry, as a primer and / or as a finish, for a substrate exposed to moderate operating conditions. The use of these coating compositions relates in particular to the market for the coating of components in the electromechanical engineering, transport and building materials industry, or construction site or agricultural machines, where components of various natures have to be painted, and with the protection in metal structures construction sites or workshops of metal structures. By way of illustration of the invention, the following examples demonstrate, without any limitation, the performances of the dispersions and coatings obtained. 1 / Raw materials a) Raw materials participating in the composition of the latex: b) Raw materials that participate in the formulation of the primer Il / Composition and use of networks: Example the A container containing 79 parts of water and 1.30 parts of Rhodafac® RS 610 (Rhodia), with a solids content of 25%, neutralized in advance at pH = 9-10 with 28% aqueous ammonia, is heated to 85 ° C. Seeding was carried out at 85 ° C using 5% of a neutralized pre-emulsion at pH = 4.5 with aqueous ammonia consisting of 33 parts of water, 1.5 parts of Rhodafac® RS 610 (SC: 25%), 25 parts of butyl methacrylate (BMA) ), 52 parts of styrene (ST), 19 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid and 1 part of PAM 100 (phosphoethoxyethyl methacrylate), and 20% of an initiator solution containing 7 parts of water and 0.40 parts of sodium persulfate Na2S208. The reaction medium is left stirring and heated for 5 minutes and then the rest of the pre-emulsion (95%) and the rest of the sodium persulfate solution are run in parallel for 4 h and 4 h 30 respectively. The medium is subsequently cooled to 65 ° C. Subsequently, a step of reducing the residual monomers running in a solution, in parallel and for 30 minutes, containing 1 part of water and 0.05 parts of (CH3) 3COOH (SC: 70%) and a solution containing 1 part was carried out. of water per 0.04 parts of SFS activator (SC: 76.6%). Subsequent additions: gradual addition, with agitation, of an aqueous solution of Disponil A3065 (l / l in water) in an amount of 1% of Disponil A3065 active to dry polymer, rinse and keep stirring at the reaction temperature, for 30 a 45 minutes. Neutralization with NH40H after cooling to 30 ° C.

Addition of biocide at room temperature.

Example Ib: (Counterexample) The same process as in example 1, the amounts of acrylic acid and PAM 100 are respectively adjusted to 2 parts by weight.

Examples lia to IVc: The same process as in the example, however, with variation in the amounts and nature of the monomers and comonomers, in the amounts of acrylic acid and PAM 100 or PEM (phosphoethyl methacrylate), and possible subsequent modifications (see Table I) . Also, the addition of bishidracide of adipic acid in the examples lia and lid was carried out at the end of the process, after neutralization with NH 4 OH. In contrast, the diacetone acrylamide of example lia is introduced after the feeding of the monomers has been completed.

Examples lie, Ule, IVb and IVc are outside the invention.

Example V: Test carried out in accordance with: Example 3: Sample polymer 7 of EP 1 193 298 A1, pages 7 and 8 (see Table I).

Ill / Implementation and tests of the films: 1 / Formulations for metal primers, final finishes and DTM lacquers: Below are formulations for: a) metal primers; b) Final DTM finishes (direct to metal) and c) Lacquers on which the tests were carried out. 2 / Application and testing of coatings: 2 / a Metal primers Coating capacity (RY): the quality of the pigment dispersion is determined based on the opacity or coating capacity of the film applied to a Lenata 2A white / black chart. The coating capacity RY is the contrast ratio RY calculated from the Y values measured respectively in the paint film, applied as a wet layer of 150 μm, to the black parts and to the white parts of the Lenata chart (% And of the film applied to the black part / Y% of the film applied to the white part). Resistance to continuous salt spray: the primers were applied as a film with a thickness of approximately 75 μm (dry film) to cold-rolled steel panels without luster, with reference Q-Panel S36 (Labomat). After drying at room temperature for 4 days and at 50 ° C for 72 hours, the test samples were stored for 24 hours at 23 ° C and 50% relative humidity for 24 hours and then subjected to accelerated aging for 240 hours with salt spray in accordance with NF ISO 9227 standard.

The blistering and oxidation are determined using two methods: - in a part without notch; - evaluation of the degree of blistering according to ISO 4628/2 and evaluation of the degree of oxidation according to ISO 4628/3; - In a transverse grooved part, the progress of corrosion is evaluated using two methods: thickness of the oxidation line: measurement of the width (in mm) of the blistering oxidation strip: measurement of the width (in mm) of the area raised by the blister After 2 hours of conditioning at 23 ° C and a relative humidity of 50%, the adhesion of the film to the substrate was approved according to ISO 2409 in the region without notch, by cross-section of the region and removing a tape adhesive 3M 610. The adhesion to the cross notched portion was evaluated simply by removing the adhesive tape applied directly to the notched region. All the results obtained in the primers are given in table Il / a. 2 / b Finished finishes DTM brightness The nets used as glossy paint with PVC = 19 in accordance with the formulation l / b were evaluated as follows: Gloss: the gloss of the films applied with a wet thickness of 200 μm on glass was measured after one week of drying under conditions controlled (25 ° C / 50% relative humidity) using a micro-tri brightness meter (micro-tri-gloss-meter) by Byk-Gardner.

Resistance to continuous salt spray: the paintings are evaluated in 2 different systems: - either a DTM finishing system (direct to metal): the paints are applied directly to the metal with a thickness of approximately 50 μm on panels with the reference panels Q-panel S36 (see 2 / a) - or the PR system / TC (primer plus final finish): after 24 hours of drying, the final finishing paints are applied at approximately 30 μm, on a primer formulated with the composition latex of Table I, the primer itself is applied with a thickness of approximately 50 μm to panels Q- panel S36. The test panels were conditioned, aged and evaluated as described above in the case of the primers. The results obtained in the final finishes are presented in table Il / b. 2 / c Lacquers The lacquer formulated with the latex of Example Illd of Table I is diluted with water at a viscosity of 31 seconds Ford Cup CF4 and a solids content (SC) of 39% by weight. The varnish is applied using a bar applicator as a 50 μm thick wet film on a PP sheet (polypropylene) transparent corona treatment of 80 μm and on HIPS (high impact polystyrene). After 15 minutes of drying under ambient conditions, the film was placed in an oven for 30 minutes at 50 ° C. The film was then conditioned for 60 h at 23 ° C and 50% relative humidity before testing. The film was clear and uniform, with the HB pencil hardness grade. The film is flexible and resistant to bending inwards from the height of the PP without fracturing or delaminating in the bend of the fold. It also adheres to HIPS using the cross-sectional test with the detachment of 3M 610 tape.

Blocking test: two films were pressed together, face to face, at a temperature and pressure given for a certain time and, then, the two films were separated and their damage was evaluated. The result is expressed on a scale of 1 to 5, where 1 means that the films adhered to each other to such an extent that they are severely damaged when they are separated and 5 means no union. - blocking after 16 h at 23 ° C at relative humidity (RH) of 50% and under a load of P = l kg / cm2: the result is 5, which means no union, - blocking after 72 h at 60 ° C with relative humidity of 70% and under load of P = 0.5 kg / cm2: the result is 1 which means that the 2 films adhered to each other to such a degree that they deteriorate seriously when separated. The film resists the following chemical agents: 100% ethanol on the PP: the film resists 30 minutes, but stains after a longer contact time; 100% ethanol in HIPS: after 10 double rubs with a felt, the film was attacked on the surface, concentrated industrial detergent solution (Teepol and window cleaner): the film remained without stain after 24 h; and - hand cream: the film resists 7 hours but was stained after prolonged contact. 3 / Comments regarding the results: 3 / a Metal Primer The results presented in table IA illustrate the need for the polymer to have a high enough level of acid, predominantly carboxylic acid, to achieve a satisfactory compromise in performance, in particular pigment dispersion and stability of the formulation. This level is determined by the hydrophobicity of the comonomers and by the PVC of the coating. By introducing a covalent crosslinking system into the composition, the protective effect of the coating is improved. 3 / b DTM final finish The networks of the invention, used in a glossy finish finish formulation, applied in both a DTM system and a PR / TC system, exhibited better corrosion resistance than a commercial standard latex for metal, intended for the use of the metal and designated BM (reference mark) in table Ilb, but also networks of similar composition, with a strong relative strong acid ratio (c / b + c) greater than 0.4. 3 / c Lacquers Composition latex IIId presents a good level of performance when applied to both metal and plastic.

Table I: SC = solids content; o = size of the particles; pH = pH of the latex after neutralization MFT = minimum film formation temperature; Tg = vitreous state transition temperature Synthesis and pigment stability: VG = Very good, G = good, FG = Almost good, M Mediocre, VM = Very mediocre Adhesion according to ISO 2409: 0 = No detachment 5 = More than 65% of film is released Blister ratio according to ISO 4628/2; Blister density according to ISO 4628/2; Oxidation according to ISO 4628/3 standard.

Table IIB; Performance of networks as formulations of final finishes (DTM and PR / TC)

Claims (26)

1. An aqueous dispersion of polymer, characterized in that the polymer can be obtained from a mixture of monomers comprising, in parts by weight: a) 100 parts of at least one ethylenically unsaturated monomer not comprising an ionic group, b) 0.5 a 15 parts of at least one ethylenically unsaturated monomer carrying at least one carboxyl group and / or a carboxylic anhydride functional group; c) at least one ethylenically unsaturated monomer carrying at least one second functionality selected from: phosphate, phosphonate or phosphinate, in an amount such that the ratio c / (b + c) varies from 0.05 to 0.4, d) 0 to 2 parts of at least one ethylenically unsaturated monomer bearing at least one alkoxysilane functional group , e) 0 to 5 parts of at least one ethylenically unsaturated monomer carrying at least one active carbonyl functional group or other functional group that reacts with an aldehyde functional group, such as a derivative ureidode, morpholine, imidazoline; oxazolidine, aziridine, or an amine functional group; f) 0 to 10, preferably 2 to 8 parts, of at least one ethylenically unsaturated monomer bearing at least one functional group selected from hydroxyl and primary or secondary amine to carry a precursor group of such functional group.

2. The dispersion according to claim 1, characterized in that it also comprises 0 to 5 parts by weight of at least one polyfunctional compound bearing at least 2 functional groups hydrazide or amine or aldehyde or a precursor of such functional group gregado after that the dispersion has been prepared by emulsion polymerization.

3. The dispersion according to claim 1 or claim 2, characterized in that monomer a) is selected from: styrene and its derivatives, ethers of (meth) acrylic alcohol of 1 to 18 carbon atoms, acrylonitrile and vinylesters, like those of versatic acid.

4. The dispersion according to any of claims 1 to 3, characterized in that the monomer b) is selected from the acids (meth) acrylic, maleic, itaconic, fumaric, vinylbenzoic, crotonic or isocrotonic and / or its anhydrides.

The dispersion according to any of claims 1 to 4, characterized in that the ethylenically unsaturated monomer c) carries at least one second phosphate-type functionality, according to one of the following general formulas: OR-O-P - (0") 2 nKi mKa * or phosphonate type R - C P (Q ".}. 2 t? K? Y + ¿or type phosphinate in which - R is an organic radical comprising an ethylenically unsaturated organic group, which may be a (meth) acrylic, vinyl or allyl group, the organic radical R may also comprise in its structure a polyalkoxylated chain comprising selected alkoxy units of oxyethylene (OE) and / or oxypropylene (OP), preferably oxyethylene (OE) and with a number of alkoxy units ranging from 1 to 30, preferably from 1 to 10; - Ri and 2 can be H or alkyl of 1 to 2 carbon atoms; and Ki1"and K2 + are an H + or an alkaline earth metal cation and ym are each equal to 0, 1 or 2, such that n + m = 2.

6. The dispersion according to any of claims 1 to 5. , characterized in that the dispersion comprises 0.5 to 5 parts of at least one surfactant per 100 parts of a) 7.

The dispersion according to any of claims 1 to 6, characterized in that it comprises at least one anionic or non-ionic surfactant. or a combination of at least one anionic surfactant and at least one nonionic surfactant 8.

The dispersion according to any of claims 6 or 7, characterized in that at least one surfactant comprises an α, β-ethylenic unsaturation. copolymerizable with monomers a), b), c), d), e) and f) 9.

The dispersion according to any of claims 1 to 8, characterized in that it contains at least one alkoxylated phosphate anionic surfactant.

The dispersion according to claim 9, characterized in that the surfactant is an alkoxylated alkyl polyether ester phosphate, the alkyl being 12, 13 or 14 carbon atoms, and the alkoxy being an oxyethylene.

11. The dispersion according to any of claims 1 to 10, characterized in that the dispersion comprises at least 2 different polymers with various glass transition temperature Tg values: - either in the form of mixtures of particles of different polymers, - or in the form of structured particles composed of at least 2 different polymer phases.

The dispersion according to claim 11, characterized in that the particles are structured according to a core / shell structure and that at least one of the monomers b) or c) or d) or e) or f) is present predominantly in one of the phases.

The dispersion according to any of claims 11 and 12, characterized in that it can be obtained: either by mixing at least 2 dispersions of polymers with different functionalities and a different Tg, or, in the case of structured particles, by a polymerization process comprising at least two successive stages with different monomer compositions.

14. A process for the preparation of the aqueous dispersion as defined according to any of claims 1 to 13, characterized in that it comprises at least the following steps: i) polymerization of at least one monomer composition as defined in accordance with any of claims 1 to 10, ii) optionally, mixing at least two aqueous dispersions obtained according to step i), each of these dispersions comprises polymers with various Tg values.

15. The process according to claim 14, characterized in that it comprises at least the following steps: i) polymerization in at least one step of a monomer composition as defined by one of claims 1 to 10, ii) polymerization in at least one step of at least a second monomer composition as defined according to any one of claims 1 to 10, it being possible for this second composition to give a polymer with a value different from Tg of that of step i) and / or it being possible for at least one of the monomers b) or c) or d) or e) or f) to be in a predominant proportion in one of the monomer compositions.

16. A coating composition, characterized in that it comprises at least one dispersion as defined according to any one of claims 1 to 13 or obtained by a process as defined in any of claims 14 and 15.

17. The coating composition of according to claim 16, characterized in that the dispersion is obtained from a monomer mixture as defined according to any of claims 1 to 10 and further comprises up to 10 parts by weight of at least one ethylenically unsaturated monomer functional as defined in claim 1 in part f) and wherein the coating composition further comprises a compound that reacts with the functional groups of the functional monomer.

18. The coating composition according to any of claims 16 and 17, characterized in that the coating is a protective coating for metal or plastic substrates.

19. The coating composition according to claim 18, characterized in that the coating is a corrosion inhibiting primer or primer or a corrosion inhibiting paint.

20. The coating composition according to any of claims 16 to 19, characterized in that the coating is a pigmented layer applied in at least one layer.

21. The use of the dispersion as defined in one of claims 1 to 13, or obtained by the process as defined in any of claims 14 and 15 for coating compositions for the protection of metal or plastic substrates.

22. The use of the dispersion as defined in one of claims 1 to 13 for coating compositions for the corrosion inhibiting protection of metal substrates.

23. Use according to any of claims 21 and 22, characterized in that the coating of the metallic or plastic substrate is applied in one or more layers and in which it is pigmented.

24. The use according to any of claims 21 and 22, characterized in that the coating of the metallic or plastic substrate is applied in one or more layers and in that it is not pigmented.

25. The use according to any of claims 21 to 24, characterized in that the thickness of a coating layer varies from 10 to 150 microns, when dry.

26. A metallic or plastic substrate coated with at least one layer of at least one coating composition as defined according to any of claims 16 to 20 or obtained in accordance with the use as defined in one of claims 21 to 25