FR2892123A1 - PROCESS FOR PREPARING A GRAFT COPOLYMER, GRAFT COPOLYMER WHICH CAN BE OBTAINED BY THIS PROCESS AND USES THEREOF - Google Patents

Abstract

The subject of the present invention is a process for preparing a graft copolymer with an unsaturated fatty chain comprising at least one terminal -OH functional group in the aqueous phase. The invention also relates to a graft copolymer obtainable by this process and its uses as a binder in coating compositions and in particular in decorative or industrial paint compositions, in adhesive compositions or in mineral binder compositions.

Description

PROCESS FOR PREPARING A GRAFT COPOLYMER, COPOLYMER GRAFFE SUSCEPTIBLE

  The present invention relates to a process for preparing a graft copolymer with an unsaturated fatty chain comprising at least one terminal -OH function in the aqueous phase. SUMMARY OF THE INVENTION The invention also relates to a graft copolymer obtainable by this method and its uses as a binder in coating compositions and in particular in decorative or industrial paint compositions, in adhesive compositions or in mineral binder. In the field of coating compositions and in particular in decorative or industrial paint compositions, it is advantageous to have one-component binders stable in storage and capable of crosslinking during application. This makes it possible to have good characteristics of films acquired during the application, such as, for example, brightness associated with mechanical strength acquired during crosslinking. Binders for alkyd-based paints fulfill this dual requirement. However, these alkyd binders have the disadvantage of having low chemical resistance to solvents such as methyl ethyl ketone or aromatics such as xylene and acids and are sensitive to UV. It is therefore interesting to improve the durability of the coating compositions to associate acrylic polymers which are more resistant to solvents such as methyl ethyl ketone or aromatics such as xylene and to acids such as acetic acid and more stable to UV to alkyd binders. It has thus been proposed to carry out mixtures of aqueous dispersions of acrylic (co) polymers (latex) with alkyd resins. The disadvantage of these mixtures is that the performance of the mixtures are not very good. This is certainly related to the absence of covalent bonds between the (co) polymers (latex) acrylics and the alkyd resins therefore of crosslinking which is therefore not particularly favorable to the resistance to solvents. It has also been proposed to graft (co) polymers with alkyd resins.

  Heretofore, in order to graft a copolymer with an alkyd resin during the synthesis of the copolymer by the radical route in the aqueous phase, it has been known to add acrylic monomers to the alkyd resin and to carry out grafting via the available double bonds present in the the alkyd resin. The polymerization is then carried out by a mini-emulsion technique. However, the available double bonds of the alkyd resin are present in the polyunsaturated fatty acid type parts of the alkyd resin. These polyunsaturated fatty acid-type parts represent only about 15% by weight of the alkyd resin, for alkyd resins whose oil length is such that they have a dust-free time and a tack-free time required for applications in decorative painting. The addition of the acrylic monomers therefore has the effect of diluting the fraction of polyunsaturated fatty acids, which leads to poorer performance of the graft copolymer obtained when it is used as a binder in coating compositions. Especially when using this graft copolymer as a binder in a paint it is sensitive to solvents, it is not scratch resistant and the mechanical properties are degraded. It has also been described in WO 92/14763 by Lankwitzer Lackfabrik the possibility of grafting a copolymer with a polyunsaturated fatty acid methacrylate. However, these polyunsaturated methacrylate fatty acids are poorly soluble in water. It has therefore been described in this document to carry out a process in several steps: a first step in the solvent phase in which the polyunsaturated fatty acid methacrylate is copolymerized with at least one copolymerizable acid such as methacrylic acid, this first step to compatibilize polymethacrylate fatty acid with water; A second stage in which the product resulting from stage 1 is put into the aqueous phase after neutralization; And then polymerizes the monomer mixture in the presence of a neutralized copolymer. However, in the first step of this process, it is necessary to previously form soluble alkali compounds, which limits the chemical nature of the copolymer on which the polyunsaturated fatty acid can be grafted. On the other hand, this process requires the realization of 2 steps before starting the polymerization: one in the solvent phase and one in the aqueous phase. Due to the solvent phase stage, there is necessarily residual solvent at the end of the process which presents ecological problems.

  Finally, part of the copolymer obtained by this process remains sensitive to water. Indeed, the fatty acid groups are in a hydrophilic environment because they are associated with methacrylic acid. The soluble alkali compound is located on the surface of the graft copolymer particles. After drying, this interstitial zone rich in acid promotes the penetration of water into the film. The need existed to find a means of grafting a copolymer by an unsaturated fatty chain which does not have the drawbacks described above. That is to say that is easy to implement, which is achievable in the aqueous phase, with copolymers of a very varied nature and chemical structure, and which leads to good properties of this graft copolymer when it is used as a binder in coating compositions and in particular in decorative or industrial paint compositions, or in adhesive or inorganic binder compositions such as a mortar.

  One of the aims of the invention is also to prepare a graft copolymer which, when used as a binder in coating compositions, has good water and solvent resistance properties, good mechanical strength of the coating and in particular vis-à-vis scratches, and therefore generally a higher durability.

  Another object of the invention is also to prepare a graft copolymer which is present when it is used as a binder in adhesive or inorganic binder compositions such as a mortar with good water and solvent resistance properties. a good mechanical strength of the adhesive or inorganic binder composition with respect to the stresses, and therefore generally a higher durability.

  These and other objects are achieved by the present invention which firstly relates to a method for grafting a copolymer by an unsaturated fatty chain comprising at least one terminal alcohol function comprising the following steps: 1) A modified monomer is prepared (A) by reacting at least one linear anhydride comprising at least one C = C double bond on each side of the anhydride functional group or a cyclic anhydride comprising at least one C = C double bond in the ring comprising the anhydride functional group with at least one an unsaturated fatty chain comprising at least one terminal alcohol function, 2) dissolving this modified monomer (A) obtained in the first step in at least one monoethylenically unsaturated monomer (B), 3) the modified monomer solution (A) / monoethylenically monomer unsaturated (B) obtained in step 2 is then pre-emulsified by adding a surfactant and water with stirring, so that a emulsion with a continuous water phase, that is to say an oil-in-water emulsion, 4) the emulsion obtained in step 3 is polymerized by addition of an initiator.

  The subject of the invention is also the graft copolymer obtainable by the above process.

  The invention also relates to the use of this graft copolymer as a binder in coating compositions, in particular decorative or industrial paint compositions. We will first detail the process for preparing the graft copolymer.

  In the first step of the process, a modified monomer (A) is prepared by reacting at least one linear anhydride comprising at least one C doubleC double bond on each side of the anhydride functional group or a cyclic anhydride comprising at least one C double double bond. C in the ring comprising the anhydride function with at least one unsaturated fatty chain comprising at least one terminal alcohol function.

  Among the linear anhydrides comprising at least one C = C double bond on each side of the anhydride functional group, mention may be made in particular of acrylic anhydride or methacrylic anhydride.

  Among the cyclic anhydrides comprising at least one C = C double bond in the ring comprising the anhydride functional group, mention may in particular be made of maleic anhydride.

  When the process of the invention is carried out with a linear anhydride comprising at least one C = C double bond on each side of the anhydride functional group, one mole of an unsaturated fatty chain comprising at least one alcohol function is reacted. terminal with from 0.8 to 1.2 moles of a linear anhydride comprising at least one C = C double bond on each side of the anhydride function.

  When the process of the invention is carried out with a cyclic anhydride comprising at least one C = C double bond in the ring comprising the anhydride functional group, one mole of an unsaturated fatty chain comprising at least one alcohol function is reacted. terminal with from 0.8 to 1.2 moles of a cyclic anhydride comprising at least one C = C double bond in the ring comprising the anhydride functional group. In this case, a monoester is obtained.

  It is also possible to react two moles of an unsaturated fatty chain comprising at least one terminal alcohol function with from 0.8 to 1.2 moles of a cyclic anhydride comprising at least one C = C double bond in the cycle comprising the anhydride function. In this case we obtain a diester.

  Preferably, the diester is prepared.

  By unsaturated fatty chain comprising at least one terminal alcohol function is meant a fatty alcohol comprising at least one ethoxylated and / or propoxylated ethylene functional group or an ethoxylated and / or propoxylated drying or drying oil fatty acid comprising an OH functional group. terminal.

  By fatty alcohol comprising at least one ethylene functional group, optionally ethoxylated and / or propoxylated, is meant an optionally ethoxylated and / or propoxylated fatty alcohol having a number of carbon atoms of between 4 and 26 carbon atoms and preferably of between 10 and 26. carbon atoms.

  The fatty alcohol can be ethoxylated and / or propoxylated. One possible method for obtaining an ethoxylated and / or propoxylated fatty acid or fatty alcohol having a terminal OH function is described in the introduction to Example A.

  The fatty alcohol when it is ethoxylated and / or propoxylated has a number of moles of ethoxy and / or propoxy functions of between 1 and 25 moles and preferably of between 4 and 10 moles for one mole of fatty alcohol.

  Among the fatty alcohols comprising at least one ethylene functional group which may be ethoxylated and / or propoxylated, mention may be made in particular of oleic alcohol, linoleic alcohol or linalool.

  The ethoxylated and / or propoxylated drying or semi-drying oil fatty acids comprising terminal OH may be prepared from various semi-drying oil fatty acids having from 4 to 26 carbon atoms.

  The ethoxylated and / or propoxylated fatty acid has a number of moles of ethoxy and / or propoxy functional groups of between 1 and 25 moles and preferably of between 4 and 10 moles for one mole of fatty acid. For the record, one possible method for obtaining an ethoxylated and / or propoxylated fatty acid or fatty alcohol having a terminal OH function is described in the introduction to Example A.

  Examples of the fatty acids of semi-drying oils having from 4 to 26 carbon atoms include safflower oil fatty acid, linseed oil fatty acid, soybean oil, sesame oil fatty acid, poppy oil fatty acid, perilla oil 10 30 fatty acid, chenei oil fatty acid, fatty acid grape seed oil, corn oil fatty acid, tall oil oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, whale oil fatty acid, hevea oil fatty acid, sugar cane oil fatty acid, etc.

  Among these fatty acids, the fatty acid of safflower oil, the fatty acid of linseed oil, the fatty acid of soya oil, the perilla oil fatty acid and the like are particularly preferred. fatty acid of goat oil, tall oil fatty acid, and sunflower oil fatty acid. Unsaturated fatty acids having conjugated double bonds may also be used as part of the drying oil fatty acid and the semisiccative oil fatty acid. Examples of conjugated double bond fatty acids are Canton oil fatty acid, oiticica oil fatty acid, dehydrated castor oil fatty acid, and dicarboxylic acid fatty acid. Hidiene (trade name of conjugated double bond fatty acid, produced by Soken Kagaku Co, Ltd in Japan). The amount of conjugated double bond fatty acid is less than 30% by weight, based on the total fatty acid. The modified monomer (A) is usually prepared by reacting the two above constituents, ie a linear anhydride comprising at least one C = C double bond on each side of the anhydride functional group or a cyclic anhydride comprising at least one C = C double bond in the ring comprising the anhydride functional group with at least one unsaturated fatty chain comprising at least one terminal alcohol function at a temperature of between 40 ° C. and 220 ° C., preferably between 60 ° C. and 100 ° C., for about half an hour to 40 hours, preferably 3 to 10 hours, in the absence or in the presence of a reaction catalyst such as sodium hydroxide, although these conditions vary with the type of fatty acid used. In order to prevent the prepolymerization of the modified monomer (A), it is possible to add a polymerization inhibitor such as hydroquinone, p-benzoquinone, or hydroquinone methylether (MEHQ).

  In the second step of the process, the modified monomer (A) obtained in the first step is dissolved in at least one monoethylenically unsaturated monomer (B). The monoethylenically unsaturated monomer (B) may be chosen from the monomers usually used for the synthesis of latex. The monomers are chosen such that the graft copolymer obtained has a glass transition temperature (Tg) of between -40.degree. C. and +100.degree.

  The monoethylenically unsaturated monomer (B) may be chosen from: vinyl esters and more particularly vinyl acetate; alkyl acrylates and methacrylates in which the alkyl group contains from 1 to 10 carbon atoms, for example the methyl, ethyl, n-butyl and 2-ethylhexyl acrylates and methacrylates; vinylaromatic monomers, in particular styrene. These monomers can be used alone or in mixtures with other ethylenically unsaturated monomers with which they are copolymerizable. Mention may in particular be made of mixtures of vinylaromatic monomers and in particular styrene and of alkyl acrylates or methacrylates in which the alkyl group contains from 1 to 10 carbon atoms, for example the methyl, ethyl and n-butyl acrylates and methacrylates. 2-ethylhexyl. As non-limiting examples of monomers copolymerizable with vinyl acetate and / or acrylic esters and / or styrene, mention may also be made of ethylene and olefins such as isobutene; vinyl esters of saturated monocarboxylic acids, branched or unbranched, having from 1 to 12 carbon atoms, such as propionate, "versatate" (vinyl neodecanoate), pivalate, vinyl laurate; unsaturated mono- or di-carboxylic acid esters having 3 to 6 carbon atoms with alkanols having 1 to 10 carbon atoms, such as maleates, fumarates of methyl, ethyl, butyl, ethylhexyl; vinylaromatic monomers such as methylstyrenes, vinyltoluenes; vinyl halides such as vinyl chloride, vinylidene chloride, diolefins especially butadiene; the (meth) allylic esters of (meth) acrylic acid, the (meth) allylic esters of the mono and diesters of maleic, fumaric and itaconic acids, and the alkenic derivatives of the amides of acrylic and methacrylic acids, such as N -méthallylmaléimide. It is also possible to use copolymerizable monomers with vinyl acetate and / or acrylic esters and / or styrene which comprise a function making it possible to give the graft copolymer good adhesion properties. Phosphated monomers which make it possible to obtain a good adhesion on metal surfaces, such as vinylphosphonic acid, 2- (methacryloyloxy) ethylphosphonic acid (RN 80730-17-2), or acid. 2- (acryloyloxy) ethylphosphonic acid; 2- (methacryloyloxy) ethylphosphate of formula CH2 = C (CH3) (O00) C2H4OPO3H, or 2- (acryloyloxy) ethylphosphate of formula CH2 = CH (COO) C2H4OPO3H; or the ammonium sulfatoethyl methacrylate SEM sold by the company Laporte, or their mixture.

  The monoethylenically unsaturated monomer (B) may further comprise functional monomers capable of providing good properties of resistance to water and solvents, or to give the latex specific adhesion properties. By way of example, mention may be made of 1-methacrylamido, 2-imidazolidinone ethane sold under the trade name Sipomer WAM II by the company Rhodia, glycidyl methacrylate, vinyltriethoxysilane or vinyl monomers bearing cyclodextrin groups. 1-methacrylamido, 2-imidazolidinone ethane sold under the trade name Sipomer WAM II by the company Rhodia makes it possible to improve the adhesion of the latex composition to supports having carbonyl groups, for example supports made of polyesters, or layers of old alkyd type paintings. Vinyltriethoxysilane makes it possible to improve the adhesion of the latex composition to glass or other mineral substrates of the metal oxide type. The glycidyl methacrylate provides the possibility of crosslinking after application of the paint film through the presence of epoxy groups. The monomers copolymerizable with vinyl acetate and / or acrylic esters and / or styrene are generally used in proportions such that the glass transition temperature (Tg) of the graft copolymer obtained is between -50 ° C. and +110 ° C. .

  Preferably, the monomers copolymerizable with vinyl acetate and / or acrylic esters and / or styrene are used in proportions such that the glass transition temperature (Tg) of the graft copolymer obtained is between -40 ° C. and + C. The proportions of monomers (A) which are dissolved in at least one monoethylenically unsaturated monomer (B) are such that the amount of (A) is from 5 to 80% by weight of the modified monomer (A) relative to total weight of monomers (A) + (B). Preferably, the amount of (A) is between 5 and 50% by weight of modified monomer (A) relative to the total weight of monomers (A) + (B).

  In the third step of the process for preparing the graft copolymer, the modified monomer solution (A) / monoethylenically unsaturated monomer (B) obtained in step 2 is then pre-emulsified by adding a surfactant and stirring water. such that an emulsion with a continuous water phase is obtained, that is to say an oil-in-water emulsion. The organic phase which is the dispersed phase comprises the monomers (A) and (B). It is generally from 10% to 70% by weight relative to the total weight of the emulsion.

  The amount of (A) in the organic phase of the emulsion is between 5 and 80% by weight of modified monomer (A) relative to the total weight of monomers (A) + (B). Preferably, the amount of (A) in the organic phase of the emulsion is between 5 and 50% by weight of modified monomer (A) relative to the total weight of monomers (A) + (B). The stirring is carried out in such a way that the dispersed phase is in the form of droplets having a mean diameter of between 1 to 100 microns. Preferably, the average diameter of the droplets is between 5 and 50 microns. The surfactant which is used in this third step may be any surfactant conventionally used for emulsion polymerization processes. The surfactants that can be used are anionic, cationic or nonionic emulsifiers. A surfactant alone or a mixture of several surfactants can be used. As surfactant, the conventional anionic surfactants represented in particular by alkyl sulphates, such as sodium lauryl sulphate, alkyl sulphonates, alkyl aryl sulphates, alkyl aryl sulphonates such as sodium dodecyl benzene sulphonate, aryl sulphates, aryl sulphonates and alkyl ethoxylates, are generally used. , alkylarylethoxylated, alkylethoxylated or alkylarylethoxylated sulfated or phosphated or their salts, sulfosuccinates, alkylphosphates of alkali metals, hydrogenated or non-hydrogenated abietic acid salts, or fatty acid salts such as sodium stearate. It is preferred to use anionic or nonionic emulsifiers. They are generally employed in a proportion of 0.01 to 5% by weight relative to the total weight of the monomers.

  The use of one of the anionic surfactants mentioned above can also be coupled with a water-soluble non-ionic polymer, such as, for example, polyvinyl alcohol or polyvinylpyrrolidone (PVP). The use of one of the anionic surfactants mentioned above can also be coupled with a stabilizing system based on synthetic anionic polymers, for example poly (meth) acrylic acid, poly (meth) acrylamide, polyvinylsulphonic acids. and water-soluble copolymers thereof, or condensates such as melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, styrene / maleic acid copolymers, and maleic acid vinyl ether copolymers.

  In the fourth step of the process for preparing the graft copolymer, the emulsion obtained in step 3 is polymerized by addition of an initiator.

  It is a radical polymerization, so it can be initiated by a free radical initiator. Suitable free radical initiators are known to those skilled in the art. Any system generating free radicals that is effective at the polymerization temperature can be used. It is possible to use a water-soluble or oil-soluble polymerization initiator. Systems generating free radicals include, for example: organic peroxides, such as benzoyl peroxide, lauroyl peroxide and dicumyl peroxide, inorganic persulfates such as sodium persulfate, potassium persulfate, ammonium persulfate Azobis (isobutyronitrile) (AIBN), redox pairs such as Fe2 + / H2O2, ROH / Ce4 + (where R represents an organic group such as a C1-C6 alkyl group, or a C5-C8 aryl group) ) or K2S2O8 / Fe2 +.

  It is employed in an amount of between 0.05 and 2% by weight relative to the total of the monomers. The reaction temperature, depending on the initiator used, is generally between 0 and 100 C, and preferably between 30 and 90 C. The preferred polymerization temperature depends on the choice of the initiator.

  The size of the graft copolymer particles which is formed in the emulsion is between 60 nm and 300 nm. In general, the polymerization is carried out in a reactor in which water, a surfactant chosen from the list of surfactants used for the production of the emulsion in step 3 of the preparation process, is first introduced. above, and an initiator. This mixture is heated to the polymerization temperature, and the preemulsion prepared in step 4 is added continuously so as to better control the exothermicity of the polymerization. It is also possible to use a transfer agent in proportions ranging from 0 to 3% by weight relative to the monomer (s), generally chosen from mercaptans such as N-dodecylmercaptan or tert-dodecylmercaptan, cyclohexene, halogenated hydrocarbons such as chloroform, bromoform, carbon tetrachloride. It adjusts the length of the molecular chains. It is added to the reaction medium either before the polymerization or during polymerization.

  The subject of the invention is also the graft copolymer obtainable by the process described above.

  The aqueous graft copolymer dispersion can be used as is, or can be dried to obtain a powder. Depending on the uses of the graft copolymer, suitable drying processes will be used. Thus, if it is a use of the graft copolymer as a binder in a coating composition such as a paint composition, it is possible to use the drying methods usually used to produce powder coatings. Powder coatings can be described as "solid paints" that can be melted to form a continuous film on the substrate (often metal, but wood, some substitute wood, ceramics, glass and some plastics can also be painted). The powders may be "thermoplastic" or "thermosetting". Thermosetting powders crosslink and polymerize with heat, while thermoplastic powders remain heat sensitive. It is for this reason that the term "powder coatings" used in industry generally refers to thermosetting powder coatings.

  These paints are easily sprayed electrostatically or tribostatically onto the substrate: as the thickness increases, the paint "self-polishes" to produce a relatively homogeneous film thickness. The object painted with the powder is then dried in the oven. The powder melts and forms a continuous film, before chemically reacting and becoming a solid and inert coating. They have a number of advantages over traditional liquid paints, especially with regard to the environment since they are 100% solid, they contain virtually no volatile organic compounds. Emissions to the environment are negligible. The process of manufacture of powder paints and their mode of application is described in the following paragraphs: 1) Pre-mixing After a precise weighing, all the dry raw material (polymer, pigment, additives) is mixed in a large mixer in order to to obtain as homogeneous a mixture as possible. In a way, the procedure resembles the mixing of the liquid paint, with the difference that lateint, as well as all other properties of the finished powder are fixed at that time. The mixture must be perfect. 2) Extrusion The premix is then passed through an extruder comprising a heated tube in which (generally) two screws pivot. The mixture of heat and friction, caused by the shearing of the screws, melts the resin and thoroughly mixes all the other ingredients (mainly pigments and fillers), dispersing them in the molten resin. The ingredients stay only about 15 seconds in the extrusion zone. It is therefore essential to have a homogeneous premix to obtain a homogeneous powder paint. The mixture exits the extruder as a hot, extremely viscous (C.sub.130 C.) liquid. Since the resin is thermosetting, it is imperative to cool the mixture as fast as possible to avoid any hardening reaction. The extruded product immediately passes into a system of water-cooled nip rollers which flatten it until a thin strip (about 2mm thick and 1m wide) of wide surface is obtained. The ribbon is still a little warm at this time (about 70-80 C), but its temperature is reduced to room temperature during its passage on a metal conveyor also cooled by water. At the end of the conveyor, the ribbon is at room temperature and brittle, ready to be granulated in storage containers 3) Grinding The granulated "chip" is then conveyed to a mill. The latter has a rotor with pins pivoting at about 6000 rpm inside a chamber with serrated walls. The chips are thrown violently against the pins, the wall and the other chips until they are transformed into a fine powder. 4) Applying the powder There are two main types of electrostatic gun: the corona discharge gun and the tribostatic guns. The subject of the invention is also the graft copolymer powder that can be obtained by the powder-paint preparation process. In the same way, if it is a use of the graft copolymer as a binder in a mineral binder composition such as a mortar, it is possible to use the drying processes usually used to produce polymer powders. redispersible. The redispersible powder is preferably prepared by spray drying the aqueous graft copolymer dispersion optionally under nitrogen to prevent oxidation of the double bonds of the graft copolymer. This drying is carried out in conventional spray drying systems, using atomization by means of single, double or multiple liquid nozzles or a rotating disk. The discharge temperature selected is generally in the range of 50 to 100 ° C, preferably 60 to 90 ° C, depending on the system, the glass transition temperature of the graft copolymer, and the desired degree of drying. In order to increase the storage stability and flowability of the redispersible graft copolymer powder, it is preferable to introduce an anti-caking agent into the spray column together with the aqueous graft copolymer dispersion. which results in a preferable deposition of the anti-caking agent on the particles of the dispersion. The preferred anti-caking agents are aluminum silicates, calcium or magnesium carbonates, or mixtures thereof, silicas, hydrated alumina, bentonite, talc, or mixtures of dolomite. and talc, or calcite and talc, kaolin, barium sulfate, titanium oxide, or calcium sulfoaluminate (satin white). The particle size of the anti-caking agents is preferably in the range of 0.001 to 0.5 mm.

  It is also possible to introduce, before drying, a conventional redispersion agent such as, for example, polyvinyl alcohol, N-vinylpyrrolidone, formaldehyde / naphthalenesulfonic acid condensates, formaldehyde / phenylsulfonic acid condensates, or homopolymers of 2-acrylamido acid. -2-methylpropanesulfonic acid.

  The invention also relates to the redispersible graft copolymer powder obtainable by the method described above. In most cases, the pulverulent compositions according to the invention are completely redispersible in water at ambient temperature by simple stirring. By totally redispersible is meant a pulverulent composition according to the invention which, after addition of a suitable amount of water, makes it possible to obtain a reconstituted graft copolymer whose particle size of the particles is substantially identical to the particle size of the copolymer particles. grafted present in the starting emulsion before drying. Following this redispersion, the particle size of the reconstituted graft copolymer obtained is measured by laser granulometry. The more the particle size of the reconstituted graft copolymer is close to that of the graft copolymer used in the synthesis of the pulverulent composition, the better is the redispersibility. The invention also relates to the reconstituted graft copolymer obtained by redispersion in water of a powdery composition as defined above.

  Finally, the invention relates to the use of the graft copolymers of the invention as a binder in coating compositions, and in particular in decorative or industrial paint compositions, or as a binder in adhesive compositions, or even as a binder in inorganic binder compositions such as mortars. The graft copolymer binder compositions of the invention have improved solvent and mechanical strength.

  If it is binders used in coating compositions, this better resistance to solvents and better mechanical strength will increase their life or the duration of their presence on the substrate they protect. Their resistance to aging can also be increased. Their resistance to dimensional variations of the support can also be increased.

  In the present description the term "paint" is used in the broad sense to denote any coating of polymeric nature deposited on a substrate and possibly having a protective function thereof, and more particularly to designate the actual aqueous paints, varnishes and lasures. The terms stain and varnish have the usual meaning in the technical field concerned here. It will be specified for the glaze that it is generally a formulation or transparent or semi-transparent composition applied to the wood or on the substrate and intended to protect it and whose solids content may be of the order of 10. % by weight or of the order of 40 to 50% by weight depending on whether it is a primary or finishing varnish. For the varnish it is a formulation or composition more concentrated than the stain.

  The invention is generally applicable to any type of aqueous paints, especially any type of stain or varnish, used on any substrate. This substrate may be in particular wood or metals, or a mineral substrate not covered with paint or a substrate covered with a primer or an old paint layer to be renovated.

  In the case where the substrate is a metal, the invention can be applied to automotive paints. When the graft copolymer of the invention is used as a binder in a coating composition the amount of graft copolymer present in a coating composition is between 10 to 95% by volume fraction.

  Preferably, when the graft copolymer of the invention is used as a binder in a coating composition the amount of graft copolymer present in a coating composition is between 20 to 85% by volume fraction. When the graft copolymer of the invention is used as a binder in a mineral binder composition the amount of graft copolymer present in a mineral binder composition is between 0.5 to 30% by mass fraction.

  Preferably, when the graft copolymer of the invention is used as a binder in a mineral binder composition, the amount of graft copolymer present in a mineral binder composition is between 1 and 10% by mass fraction. By inorganic binder is meant aerial binders or hydraulic binders.

  Among the aerial binders may be mentioned plasters. Among the hydraulic binders include cements that can be Portland type, aluminous or blast furnaces, fly ash, calcined schists or pozzolans. Preferably the hydraulic binders are cements.

  The inorganic binders have the property of crystallizing in the presence of water, and thus of "setting". They make with water a gradually hardening paste, even in the absence of air and especially under water. Mixed with sand and gravel, and depending on their nature, they can make concrete, mortars, or serious road. When the graft copolymer of the invention is used as a binder in an adhesive composition the amount of graft copolymer present in an adhesive composition is between 70 to 100% by volume fraction. Preferably, when the graft copolymer of the invention is used as a binder in an adhesive composition, the amount of graft copolymer present in an adhesive composition is from 80 to 100% by volume fraction.

  The invention also applies to varnishes used in cosmetics. Depending on the intended application and the desired level of performance, it may be appropriate to use the graft copolymers of the invention in compositions comprising a drying agent. This is the case for coating compositions or adhesive compositions.

  The siccative agent is a catalyst promoting the oxidation of double bonds corresponding to unsaturations of the fatty acid. The use of a drying agent makes it possible to accelerate the crosslinking of the binder and to reach a good level of mechanical strength and solvent resistance more quickly. However, the graft copolymer according to the invention achieves good mechanical properties and solvent resistance without adding drying agent. This implementation can be interesting in the case where the user wants to be free from the presence of heavy metals (cobalt salts for example) to meet requirements of respect for the environment. The drying of the coating composition, paint or varnish, comprising the graft copolymer of the invention after its application on a support can be carried out at room temperature. This drying can also be carried out at high temperature if the application conditions allow it, that is to say between 30 C and 300 C, and preferably between 30 C and 100 C, which has the consequence of increasing still the level of crosslinking.

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

  EXAMPLES Example A Preparation of graft copolymers with unsaturated fatty chains comprising a terminal OH-function and preparation of comparative examples

  Introduction: Description of a possible method for obtaining a fatty acid or an ethoxylated and / or propoxylated fatty alcohol having terminal OH function: 1 mol of fatty alcohol or fatty acid is mixed in a 2 liter autoclave. 0.0286 moles of potassium hydroxide are added as a 45% solution in water. The mixture is maintained under a nitrogen atmosphere and is drawn under vacuum at 120 ° C to remove a maximum of water. The temperature of the autoclave is raised to 150 ° C. Propylene oxide and / or ethylene oxide are introduced in the desired proportions. The introduction of these oxides can also be carried out continuously while maintaining the temperature at 150 ° C. At the end of this introduction, the temperature is maintained at 150 ° C. for one hour. The residual propylene oxide and / or ethylene oxide is then removed by drawing under vacuum at 120 ° C. for 15 minutes, after which the product is cooled and recovered. The amount of propylene oxide and / or ethylene oxide introduced during the reaction determines the number of propoxy and / or ethoxy units present in the fatty alcohol or the ethoxylated and / or propoxylated fatty acid.

  Comparative Example 1 Synthesis of a Resinless Latex Having a Tg of 50 ° C. (Tg is the Glass Transition Temperature) 173 g of purified water, 5.26 g of Sipomer COPS1 sold by the company Rhodia, and 5g of Simulsol 546 SN anionic surfactant marketed by the company SEPPIC. A solution of 0.2 g of ammonium persulfate in 10 g of purified water is prepared separately. A pre-emulsion having the following composition is also prepared: 200 g of purified water 3.8 g of Simulsol 546 SN 385 g of methyl methacrylate 13 g of acrylic acid 100 g of 2-ethylhexyl acrylate This mixture is stirred in order to obtain a pre-emulsion. emulsion having droplet sizes around 0 microns. The reactor solution is heated to 80 ° C. and stirred. The ammonium persulfate solution is poured in one go. Then the preemulsion is added at a constant rate over 4 hours while maintaining the temperature at 80 ° C. In parallel over 5 hours, a second solution of ammonium persulfate in water comprising 1.5 g of water is introduced into the reactor. ammonium persulfate and 300g of purified water. The temperature of the mixture is then maintained in the reactor at 80 ° C. for 1 hour. It is cooled to 20 ° C. and the latex is then neutralized with a 10% sodium hydroxide solution. A latex having a solids content of 40%, a viscosity of 100 cp and a pH of 7.5 is obtained.

  Comparative Example 2 Synthesis of a latex without resin having a Tg of 17 C. 173 g of purified water, 5.26 g of Sipomer COPS1 marketed by Rhodia, and 5 g of Simulsol 546 SN surfactant are placed in a polymerization reactor. anionic marketed by the company SEPPIC. A solution of 0.2 g of ammonium persulfate in 10 g of purified water is prepared separately. A pre-emulsion having the following composition is also prepared: 200 g of purified water 3.8 g of Simulsol 546 SN 280 g of methyl methacrylate 13 g of acrylic acid 200 g of 2-ethylhexyl acrylate This mixture is stirred to obtain a pre-emulsion having droplet sizes around 0 microns. The reactor solution is heated to 80 ° C. and stirred. The ammonium persulfate solution is poured in one go. Then the preemulsion is added at a constant rate over 4 hours while maintaining the temperature at 80 ° C. In parallel over 5 hours, a second solution of ammonium persulfate in water comprising 1.5 g of water is introduced into the reactor. ammonium persulfate and 300g of purified water.

  The temperature of the mixture is then maintained in the reactor at 80 ° C. for 1 hour. It is cooled to 20 ° C. and the latex is then neutralized with a 10% sodium hydroxide solution. A latex having a solids content of 42%, a viscosity of 200 cp and a pH of 7.5 is obtained. Example 1 According to the Invention - Synthesis of the Grafted Monomer Copolymer Hybrid (Al) and the Latex of Comparative Example 1

  a) synthesis of the monomer (Al) 10 -synthesis of the ethoxylated fatty alcohol the starting product is a linoleic alcohol HD-ocenol 110/130 sold by the company Cognis. This is ethoxylated with 5 moles of ethylene oxide according to the method described in the introduction to Example A.

  Synthesis of the monomer (Al) 0.1 mol of ethoxylate is placed in a reactor heated to 65 ° C., a free radical polymerization methylether of hydroquinone (MEHQ) is added in a quantity of 2000 ppm relative to the total weight of the mixed. Purge is carried out with previously dried air. 0.2 moles of methacrylic anhydride are added. From the moment when the exothermicity of the reaction is noted (approximately 10 minutes), the temperature of the reaction is readjusted at 72 ° C. 30 minutes after the introduction of the anhydride, a catalyst is added which is sodium hydroxide. (50% sodium hydroxide solution) in a propotion of 0.05 moles. It is allowed to react at 72 ° C. for 3 hours. In order to keep the monomer (Al) thus obtained in liquid form, it is cooled to 60 ° C. and a premix of methacrylic acid and water is added to the monomer (Al) to obtain a final composition of 20% of water, 20% of methacrylic acid and 60% of monomer (Al b) Synthesis of the hybrid graft copolymer monomer (Al) and latex of Comparative Example 1 is prepared a solution of Simulsol 3.8g in 200g of purified water. This mixture is stirred with a magnetic stirrer. In parallel, a mixture of 35 35 g of methyl methacrylate 69 g of monomer (Al) as prepared in point a) 13 g of acrylic acid and 64 g of 2-ethylhexyl acrylate are prepared. This mixture is stirred at ambient temperature until a homogeneous and clear solution is obtained. The above mixture is poured with stirring into the Simulsol solution to obtain a stable pre-emulsion having a droplet size of about 10 microns.

  Then the polymerization is started as indicated in Comparative Example 1: 173 g of purified water, 5.26 g of Sipomer COPS1 marketed by Rhodia, and 5 g of Simulsol 546 SN anionic surfactant sold by the company SEPPIC. A solution of 0.2 g of ammonium persulfate in 10 g of purified water is prepared separately. The reactor solution is heated to 80 ° C. and stirred. The ammonium persulfate solution is poured in one go. Then the preemulsion is added at a constant rate over 4 hours while maintaining the temperature at 80 ° C. In parallel over 5 hours, a second solution of ammonium persulfate in water comprising 1.5 g of water is introduced into the reactor. ammonium persulfate and 300g of purified water. The temperature of the mixture is then maintained in the reactor at 80 ° C. for 1 hour. It is cooled to 20 ° C. and the latex is then neutralized with a 10% sodium hydroxide solution. A latex having a solids content of 39.5%, a pH of 7.5, a low grain content (<400 ppm) and a size of about 150 nm to 200 nm is obtained.

  Example 2 According to the Invention - Synthesis of the Grafted Monomer Copolymer Hybrid (Al) and the Latex of Comparative Example 2

  a) synthesis of the monomer (Al) is the same synthesis as that described in Example 1 according to the invention above. b) Synthesis of the hybrid graft copolymer monomer (Al) and latex of Comparative Example 2 is prepared a solution of Simulsol 3.8g in 200g of purified water. This mixture is stirred with a magnetic stirrer. In parralel there is prepared a mixture of: 247g of methyl methacrylate 69g of monomer (Al) as prepared in point a) 13g of acrylic acid 168g of 2-ethylhexyl acrylate. This mixture is stirred at ambient temperature until a homogeneous and clear solution is obtained. The above mixture is poured with stirring into the Simulsol solution to obtain a stable pre-emulsion having a droplet size of about 10 microns.

  Then the polymerization is started as indicated in Comparative Example 1: 173 g of purified water, 5.26 g of Sipomer COPS1 marketed by Rhodia, and 5 g of Simulsol 546 SN anionic surfactant sold by the company SEPPIC. A solution of 0.2 g of ammonium persulfate in 10 g of purified water is prepared separately. The reactor solution is heated to 80 ° C. and stirred. The ammonium persulfate solution is poured in one go. Then the preemulsion is added at a constant rate over 4 hours while maintaining the temperature at 80 ° C. In parallel over 5 hours, a second solution of ammonium persulfate in water comprising 1.5 g of water is introduced into the reactor. ammonium persulfate and 300g of purified water. The temperature of the mixture is then maintained in the reactor at 80 ° C. for 1 hour. It is cooled to 20 ° C. and the latex is then neutralized with a 10% sodium hydroxide solution. A latex having a solids content of 42.3%, a pH of 7.5 and a size of about 150 nm to 200 nm is obtained.

  Example 3 According to the Invention - Synthesis of the Grafted Monomer Copolymer Hybrid (A2) and the Latex of Comparative Example 2

  a) synthesis of the monomer (A2) -synthesis of the ethoxylated fatty acid the starting material is a fatty acid, ethoxylated oleic acid having 4 moles of ethoxylation per mole of fatty acid marketed by the company Rhodia under the name Alkamuls A2. -synthesis of the monomer (A2) is the same synthesis as that of the monomer (Al) described in Example 1 according to the invention above. 0.1 mol of ethoxylate is placed in a reactor heated to 65 ° C., a methylether hydroquinone radical polymerization inhibitor (MEHQ) is added in a quantity of 2000 ppm relative to the total weight of the mixture.

  Purge is carried out with previously dried air. 0.2 moles of methacrylic anhydride are added. From the moment when the exothermicity of the reaction is noted (approximately 10 minutes), the temperature of the reaction is readjusted at 72 ° C. 30 minutes after the introduction of the anhydride, a catalyst is added which is sodium hydroxide. (50% sodium hydroxide solution) in a propotion of 0.05 moles. Allowed to react at 72 C for 3 hours. In order to keep the monomer (A2) thus obtained in liquid form, it is cooled to 60 ° C. and a premix of methacrylic acid and water is added to the monomer (A2) to obtain a final composition of 20% of water, 20% methacrylic acid and 60% monomer (A2). b) Synthesis of the hybrid graft copolymer monomer (A2) and latex of Comparative Example 2 is prepared a solution of Simulsol 3.8g in 200g of purified water. This mixture is stirred with a magnetic stirrer. In parralel there is prepared a mixture of: 247g of methyl methacrylate 72g of monomer (A2) as prepared in point a) 13g of acrylic acid 168g of 2-ethylhexyl acrylate. This mixture is stirred at ambient temperature until a homogeneous and clear solution is obtained. The above mixture is poured with stirring into the Simulsol solution to obtain a stable pre-emulsion having a droplet size of about 10 microns.

  Then the polymerization is started as indicated in Comparative Example 1: 173 g of purified water, 5.26 g of Sipomer COPS1 marketed by Rhodia, and 5 g of Simulsol 546 SN anionic surfactant sold by the company SEPPIC.

  A solution of 0.2 g of ammonium persulfate in 10 g of purified water is prepared separately.

  The reactor solution is heated to 80 ° C. and stirred. The ammonium persulfate solution is poured in one go. Then the preemulsion is added at a constant rate over 4 hours while maintaining the temperature at 80 ° C. In parallel over 5 hours, a second solution of ammonium persulfate in water comprising 1.5 g of water is introduced into the reactor. ammonium persulfate and 300g of purified water. The temperature of the mixture is then maintained in the reactor at 80 ° C. for 1 hour. It is cooled to 20 ° C. and the latex is then neutralized with a 10% sodium hydroxide solution. A latex having a solids content of 42%, a pH of 7.5 and a size of about 150 nm to 200 nm is obtained.

  Example B - description of the tests used We will first describe the different tests that were used and then present the results obtained for the examples of the invention and the comparative examples.

  I- rub test methyl ethyl ketone test 1. principle This test involves subjecting the paint or varnish film to the repeated rubbing of a cotton soaked in methyl ethyl ketone (MEK) and examine the part tested. The result of this test is relatively dependent on the operator, it is recommended to test a reference product in parallel or to consider this test as a comparative method. 2. bibliographical references The present procedure is based on the ASTM D4752 standard of 1987. 3. materials and products The test is carried out on aluminum support AL36 (chromated aluminum) of the Q-PANEL supplier. It also uses hydrophilic cotton and methyl ethyl ketone (no special specification). 4. Procedure The support is a binder film applied at 150 microns wet on a metal plate. The cotton is imbibed with methyl ethyl ketone. We rub the test film with this cotton with a pressure of about 2 kg by making it back and forth.

  We stop the test when the cotton begins to stick to the film or after 20 double rubs if nothing happens. We examine the surface.

  Methyl ethyl ketone is put back on the cotton if it seems dry and we start again. We stop the test when the media appears. If it does not appear, we go to maximum up to 200 double rubs. NB: A double rub is a round-trip friction performed on the plate.

  II- Chemical resistance test: drop test 1. principle The binder film is exposed to a drop of chemical for a period of 30 min. After this exposure, the condition of the film is evaluated. It is recommended to place a reference product among those tested in order to use this test as a comparative method. 2. materials and products The binder to be tested is applied at 150 microns wet on a chromated aluminum type metal plate (ref AL36 at supplier Q-PANEL) The following chemical agents are used: - about 10% sulfuric acid (in weight), - about 25% (by weight) acetic acid, - about 20% (by weight) ammonia, - ethanol 96, - xylene, methyl ethyl ketone. 8. Procedure A drop of the reagent is deposited on the binder. The set is covered with a watch glass or a plastic stopper. After 30 minutes, the reagent is removed from the film by wiping with a paper towel. In some cases, a new notation is made half an hour after removing the watch glass (noted aspect after 30 min).

  9. Expressions of the results The state of the binder film is evaluated by giving a score of 0 to 5 according to the following rating: 0: The film is not attacked, the reagent leaves no trace. 1: There is a mark corresponding to the perimeter of the drop. The inner part is identical to the rest of the film in appearance and touch. 2: There is a loss of gloss, or the film is snapping (very softened), or staining. 3: The film has 2 or 3 defects of the note 2. 4: The film is pleated or sticky without much cohesion. We can also observe a bead on the periphery of the drop. : The film was completely destroyed, the support is bare.

  5 III- Hardness Persoz 1. Principle The test consists of measuring the damping time of a pendulum resting, by means of two steel balls, on the film to be studied. 2. Bibliographical references The present procedure was drafted following the NFT 30-016 standard of December 1991. 3. Procedure Unless otherwise specified, the dimensions of the specimens are: * length: 150 mm minimum * width: 75 mm minimum. Their thickness in micrometers must be determined according to the method for measuring thicknesses of non-magnetic coatings on ferro magnetic and non-conductive bases on non-magnetic conductive bases according to the ISO 2360 standards of 1972 and 2808 of 1974.

  Before the test, the specimens are allowed to stand for at least 12 hours in a room where the temperature is (23 3 C) and the relative humidity is (55 10%). The experiment is then carried out in this same room. The specimen is fixed on the platform. The horizontality of the device is checked using the spirit level.

  We ensure the good condition of the balls, possibly with a magnifying glass. If necessary, a degreasing is carried out and then the pendulum is placed on the sheet to be studied. It is verified that the mirror or the photocell is parallel to the plane of movement of the pendulum and that the zero of the mirror or the cell and the rest position of the pendulum coincide. Adjustment is necessary if necessary. The pendulum is moved to the graduation 12, it is released and the stopwatch is triggered simultaneously. Stop the stopwatch when the amplitude reaches 4. In the case of devices with an automatic counting system, these operations are carried out automatically, but the type of device must be taken into account. To avoid a parallax error, the experimenter's eye must be placed in order to see his own image behind the 0 graduation. 4. Expression of the results The hardness result is the number of seconds obtained by calculating the average of 2 successive determinations carried out in 2 different places of the same test-tube.

  IV- Resistance to scratching Taber 1. Principle The test consists in measuring the minimum load necessary for the appearance of a regular scratch on a rotating specimen. An arm with a weight makes it possible to vary the load applied to the scratch tool (a diamond point) on the sheet to be studied. 2. Bibliographical references This operating procedure has been drafted following the standard EN 438 and ISO 4585-2. 3. Apparatus The Taber Scratch Resistance Meter is referenced as Model 203. 4. Test tubes Measurements are made on binders applied to glass plates to a thickness of 150 microns wet.

  Before the test, the specimens are allowed to stand for at least 12 hours in a room where the temperature is (23 3 C) and the relative humidity is (55 10%). 5. Procedure It operates in a room where the atmosphere is maintained at a temperature of (23 3 C) and the relative humidity at (55 10%).

  The specimen is attached to the platform for rotating the specimen. The horizontality of the device is checked using the spirit level. The oscillating arm equipped with a diamond point is applied to the film of varnish, the weight being adjusted so as to have the lowest pressure. The specimen is rotated.

  We check the presence or absence of scratches. If there is no scratch, increase the swingarm pressure by adjusting the weight. The measurement is repeated until the appearance of a regular and continuous streak. We note the applied pressure. 6. Expression of results The scratch resistance result is the minimum gram pressure for the appearance of a continuous and regular streak obtained by calculating the average of 2 successive determinations made at 2 different places of the same test piece. Examples C - results obtained with the examples of the invention and the comparative examples

  EXAMPLE C-1 This example concerns the evaluation of Example 1 according to the invention and the comparison of its properties with Comparative Example 1 (same composition but without resin). 150 μm films are applied to steel or aluminum plates according to the tests carried out. They are maintained at 30 ° C. to 23 ° C. and 55% relative humidity before being placed in an oven at the temperature and for the time indicated in the baking conditions column of Table 1. coalescence of the polymer particles, a coalescence agent (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate marketed by Eastman as Texanol) is added so as to obtain a film formation temperature (TMFF) of C. A drying agent (marketed by Elementis Specialties Netherlands BV under the name Nuodex Web Cobalt 8%) is added to the latexes according to the invention at a level of 0.28% relative to the dry mass of binder in order to catalyze the reaction. oxidation with air. TABLE 1 Resistance Nature of the binder Chemical conditions Hardness Persoz Steam Reaction MEC EtOH test Xylene (30 ') (30') (30 ') Example 1 according to the invention 30' to 80 C 2 2 1 135 40 Example 1 according to the invention 30 'to 30 ° C Comparative Example 1 30' to 80 ° C Comparative Example 1 30 'to 140 ° C The results obtained show that the graft copolymers according to the invention have a better chemical resistance to the three solvents considered, for the two baking temperatures (80 C and 140 C). Steaming at a higher temperature increased the hardness of the binders (including comparative examples), in part because of better removal of the coalescing agent. The advantage obtained by crosslinking after oxidation of the double bonds of the binders according to the invention appears in the rub-test results which are substantially improved, in particular after steaming at 140 ° C.

  EXAMPLE C-2 This example relates to the evaluation of Example 2 according to the invention and the comparison of its properties with Comparative Example 2 (same composition but without resin).

  150 μm films are applied to steel or aluminum plates according to the tests carried out. They are maintained at 30 ° to 23 ° C. and 55% relative humidity before being placed in an oven at the temperature and for the time indicated in the column baking conditions of Table 2. The latexes are added according to US Pat. a drying agent (marketed by Elementis Specialties Netherlands BV under the name Nuodex Web Cobalt 8%) at a level of 0.28% relative to the dry mass of binder in order to catalyze the oxidation reaction with air. Table 2 Resistance Nature of the binder Chemical conditions Hardness Persoz Steam Reaction MEC EtOH test Xylene (30 ') (30') (30 ') Example 2 according to the invention 30' to 80 C 2 1 1 117 190 Example 2 The results obtained show that the graft copolymers according to the invention have a better chemical resistance to the three solvents in question. Steaming at higher temperature increases the hardness of the binder according to the invention, which can not be attributed to better removal of the coalescing agent as in the previous example (there is no coalescing agent ) but which shows the oxidation crosslinking of the double bonds of the binder according to the invention. The rub-test results are significantly improved over the comparative example for the same reason.

  EXAMPLE C-3 This example concerns the evaluation of Example 3 according to the invention and the comparison of its properties with Comparative Example 2 (same composition but without resin). 150 μm films are applied to steel or aluminum plates according to the tests carried out. They are kept at 30 ° to 23 ° C. and 55% relative humidity before being placed in an oven at 140 ° C. for 30 minutes. A drying agent (marketed by Elementis Specialties Netherlands BV under the name Nuodex Web Cobalt 8%) is added to the latexes according to the invention at a level of 0.28% relative to the dry mass of binder in order to catalyze the oxidation reaction. with the air. The results are shown in Table 3. Table 3 Nature of the binder Chemical resistance Hardness Rub test MEC (60 ') Persoz Aspect Appearance after initial 30 Example 3 according to the invention 2-3 1-2 131 200 Example 2 comparative 4 2 The results obtained show that the graft copolymer according to the invention has a better chemical resistance to methyl ethyl ketone than the comparative copolymer. This advantage is retained if we consider the appearance of the film after evaporation of the solvent (appearance after 30 minutes). The rub-test results are also significantly improved over the comparative example.

Claims (40)

claims   A method for grafting a copolymer with an unsaturated fatty chain comprising at least one terminal alcohol functional group comprising the following steps: 1) A modified monomer (A) is prepared by reacting at least one linear anhydride comprising at least one double bond C = C on each side of the anhydride function or a cyclic anhydride comprising at least one C = C double bond in the ring comprising the anhydride functional group with at least one unsaturated fatty chain comprising at least one terminal alcohol function,   2) dissolving this modified monomer (A) obtained in the first step in at least one monoethylenically unsaturated monomer (B),   3) the modified monomer solution (A) / monoethylenically unsaturated monomer (B) obtained in step 2 is then pre-emulsified by adding a surfactant and water with stirring, so that an emulsion is obtained; with a continuous water phase, that is to say an oil-in-water emulsion,   4) the emulsion obtained in step 3 is polymerized by addition of an initiator. 2. Method according to claim 1, characterized in that in step 1, the unsaturated fatty chain comprising at least one terminal alcohol function is a fatty alcohol comprising at least one ethylenic function optionally ethoxylated and / or propoxylated. 3. Method according to claim 1, characterized in that in step 1, the unsaturated fatty chain comprising at least one terminal alcohol function is an ethoxylated and / or propoxylated siccative or semi-drying oil fatty acid comprising an OH function. terminal. 4. Method according to claim 1, characterized in that in step 1, the linear anhydride is selected from acrylic anhydride or methacrylic anhydride.   5. Method according to claim 1, characterized in that in step 1, the cyclic anhydride is maleic anhydride.   6. Process according to claim 1, characterized in that in step 1, one mole of an unsaturated fatty chain comprising at least one terminal alcohol function is reacted with from 0.8 to 1.2 moles of a linear anhydride. comprising at least one C = C double bond on each side of the anhydride function.   7. Process according to claim 1, characterized in that in step 1, one mole of an unsaturated fatty chain comprising at least one terminal alcohol functional group is reacted with from 0.8 to 1.2 moles of an anhydride. cyclic composition comprising at least one C = C double bond in the ring comprising the anhydride function.   8. Process according to claim 1, characterized in that in step 1, two moles of an unsaturated fatty chain comprising at least one terminal alcohol function are reacted with from 0.8 to 1.2 moles of an anhydride. cyclic composition comprising at least one C = C double bond in the ring comprising the anhydride function.   9. Process according to any one of claims 1 or 2, characterized in that the fatty alcohol optionally ethoxylated and / or propoxylated has a carbon number of between 4 to 26 carbon atoms and preferably between 10 and 10 carbon atoms. at 26 carbon atoms.   10. Process according to any one of claims 1 or 2, characterized in that the fatty alcohol when it is ethoxylated and / or propoxylated has a number of moles of ethoxy and / or propoxy functions of between 1 to 25 moles and preferably between 4 to 10 moles per 1 mole of fatty alcohol.   11. Process according to any one of claims 1 or 3, characterized in that the fatty acid of ethoxylated and / or propoxylated drying or semi-drying oils has a carbon number of between 4 and 26 carbon atoms. carbon carbon and preferably between 12 to 26 carbon atoms.   12. Process according to claim 1, characterized in that the fatty acid of ethoxylated and / or propoxylated drying or semi-drying oils comprising a terminal OHOH function has a number of moles of ethoxy functions and / or or propoxy of between 1 to 25 moles and preferably of between 4 to 10 moles per one mole of fatty acid.   13. The method of claim 2, characterized in that the fatty alcohol optionally ethoxylated and / or propoxylated is selected from oleic alcohol, linoleic alcohol, or linalool.   14. Process according to claim 3, characterized in that the fatty acid of ethoxylated and / or propoxylated drying or semi-drying oils comprising a terminal OHOH function is chosen from the fatty acid of safflower oil, the acid flaxseed oil, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, perilla oil fatty acid, acid fat oil of goat oil, grape seed oil fatty acid, corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, l cottonseed oil fatty acid, whale oil fatty acid, hevea oil fatty acid, sugarcane oil fatty acid, or their mixture.   15. Process according to claim 14, characterized in that the fatty acid of ethoxylated and / or propoxylated drying or semi-drying oils comprising a terminal OHOH function is chosen from safflower oil fatty acid, flaxseed oil, soybean oil fatty acid, perilla oil fatty acid, chenei oil fatty acid, tall oil fatty acid, acid fat of sunflower oil, or their mixture.   16. A process according to any one of the preceding claims, characterized in that the ethoxylated and / or propoxylated drying or drying siccative or semi-drying oil fatty acid comprising a terminal OH group comprises a part of unsaturated fatty acids having double bonds. conjugated as a portion of the fatty acid of ethoxylated and / or propoxylated drying or semi-drying oils comprising a terminal OHOH function.   17. Process according to claim 16, characterized in that the unsaturated fatty acid having conjugated double bonds is chosen from Canton oil fatty acid, oiticica oil fatty acid and fatty acid. dehydrated castor oil and Hidiene fatty acid (trade name of conjugated double bond fatty acid, produced by Soken Kagaku Co, Ltd in Japan).   18. Process according to any one of claims 16 or 17, characterized in that the amount of conjugated double bond fatty acid is less than 30% by weight, based on the total fatty acid.   19. Method according to any one of the preceding claims, characterized in that the modified monomer (A) is prepared in step 1 by reacting the two constituents at a temperature between 40 C and 220 C, preferably between 60 and 100 C, for about half an hour to 40 hours, preferably between 3 to 10 hours in the absence or in the presence of a reaction catalyst such as sodium hydroxide.   20. Process according to any one of the preceding claims, characterized in that the monoethylenically unsaturated monomer (B) is chosen such that the graft copolymer obtained has a glass transition temperature (Tg) of between 40 C and 100 C vs.   21. Process according to any one of the preceding claims, characterized in that the monoethylenically unsaturated monomer (B) is chosen from: - vinyl esters and more particularly vinyl acetate; alkyl acrylates and methacrylates in which the alkyl group contains from 1 to 10 carbon atoms, for example methyl, ethyl, n-butyl and 2-ethylhexyl acrylates and methacrylates; or - vinylaromatic monomers, in particular styrene, these monomers may be used alone or in mixtures with other ethylenically unsaturated monomers with which they are copolymerizable.   22. Process according to claim 21, characterized in that the monomethylenically unsaturated monomer (B) is chosen from mixtures of vinylaromatic monomers and in particular styrene and of alkyl acrylates or methacrylates in which the alkyl group contains from 1 to 10 carbon atoms. carbon atoms, for example, methyl, ethyl, n-butyl and 2-ethylhexyl acrylates and methacrylates.   23. The method of claim 21, characterized in that the copolymerizable monomers with vinyl acetate and / or acrylic esters and / or styrene, are selected from ethylene and olefins such as isobutene; vinyl esters of saturated monocarboxylic acids, branched or unbranched, having from 1 to 12 carbon atoms, such as propionate, "versatate" (vinyl neodecanoate), pivalate, vinyl laurate; unsaturated mono- or di-carboxylic acid esters having 3 to 6 carbon atoms with alkanols having 1 to 10 carbon atoms, such as maleates, methyl, ethyl, butyl, ethylhexyl fumarates; vinylaromatic monomers such as methylstyrenes, vinyltoluenes; vinyl halides such as vinyl chloride, vinylidene chloride, diolefins especially butadiene; the (meth) allylic esters of (meth) acrylic acid, the (meth) allylic esters of the mono and diesters of maleic, fumaric and itaconic acids, and the alkenic derivatives of the amides of acrylic and methacrylic acids, such as N -méthallylmaléimide.   24. Process according to claim 21, characterized in that the monomers copolymerizable with vinyl acetate and / or acrylic esters and / or styrene, are chosen from: phosphate monomers, such as vinylphosphonic acid, 2- (methacryloyloxy) ethylphosphonic acid (RN 80730-17-2), or 2- (acryloyloxy) ethylphosphonic acid; 2- (methacryloyloxy) ethylphosphate of formula CH2 = C (CH3) (O00) C2H4OPO3H, or 2- (acryloyloxy) ethylphosphate of formula CH2 = CH (C00) C2H40P03H; or the ammonium sulfatoethyl methacrylate SEM sold by Laporte or their mixture; 1-methacrylamido, 2-imidazolidinone ethane, glycidyl methacrylate, vinyltriethoxysilane or vinyl monomers bearing a cyclodextrin group.   25. Process according to any one of the preceding claims, characterized in that in step 2 the proportions of monomers (A) which are dissolved in at least one monoethylenically unsaturated monomer (B) are such that the amount of (A) is between 5% to 80% by weight of modified monomer (A) relative to the total weight of monomers (A) + (B), and preferably, the amount of (A) is between 5% to 50% by weight. weight of modified monomer (A) relative to the total weight of monomers (A) + (B).   26. A process according to any one of the preceding claims, characterized in that in the third step the organic phase comprising the monomers (A) and (B) constitutes from 5% to 50% by weight relative to the total weight of the product. 'emulsion.   27. Method according to any one of the preceding claims, characterized in that in the third step the stirring is carried out in such a way that the dispersed phase is in the form of droplets having a mean diameter of between 1 micron and 100 microns. microns, and preferably, the average diameter of the droplets is between 10 microns to 50 microns.   28. Process according to any one of the preceding claims, characterized in that in the third step the surfactant used is chosen from conventional anionic surfactants represented in particular by alkyl sulphates, such as sodium lauryl sulphate, alkyl sulphonates and alkylarylsulphates. alkylarylsulfonates such as sodium dodecylbenzenesulfonates, arylsulfates, arylsulfonates, alkyl ethoxylates, alkylarylethoxylates, alkyl ethoxylates or sulfated or phosphated alkylarylethoxylates or their salts, sulfosuccinates, alkylphosphates of alkali metals, hydrogenated abietic acid salts or no, or fatty acid salts such as sodium stearate.   29. Method according to any one of the preceding claims, characterized in that in the third step the amount of surfactant used is between 0.01 to 5% by weight relative to the total weight of the monomers.   30. Method according to any one of the preceding claims, characterized in that in the third step the surfactant used is coupled with a water-soluble non-ionic polymer, such as for example polyvinyl alcohol or polyvinylpyrrolidone (PVP), or with a system stabilizer based on synthetic anionic polymers, for example poly (meth) acrylic acid, poly (meth) acrylamide, polyvinylsulphonic acids, and water-soluble copolymers thereof, or condensates such as melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, styrene / maleic acid copolymers, or vinyl ether-maleic acid copolymers.   31. Process according to any one of the preceding claims, characterized in that in the fourth step the free radical initiator is chosen from organic peroxides, such as benzoyl peroxide, lauroyl peroxide and dicumyl peroxide, inorganic persulfates. such as sodium persulfate, potassium persulfate, ammonium persulfate, - azobis (isobutyronitrile) (AIBN), or - redox pairs such as Fe2 + / H2O2, ROH / Ce4 + (where R represents a organic group such as C1-C6 alkyl, or C5-C8 aryl) or K2S2O8 / Fe2 +.   32. Process according to any one of the preceding claims, characterized in that in the fourth step the free radical initiator is used in an amount of between 0.05 and 2% by weight relative to the total of the monomers.   33. Method according to any one of the preceding claims, characterized in that in the fourth step the polymerization temperature is between 0 and 100 C, and preferably between 30 and 90 C.   34. Graft copolymer obtainable by the method according to any one of claims 1 to 33.   35. Graft copolymer obtainable by the method according to any one of claims 1 to 33, characterized in that it is in powder form.   36. Graft copolymer obtainable by the method according to any one of claims 1 to 33, characterized in that it is in the form of redispersible powder.   37. Reconstituted graft copolymer obtained by redispersion in water of a powdery composition according to claim 36.   38. Use of the graft copolymer according to any one of claims 34 to 37 as a binder in coating compositions, adhesive compositions or mineral binder compositions.   39. A coating or adhesive or inorganic binder composition comprising a graft copolymer according to any one of claims 34 to 37.   40. A coating or adhesive composition according to claim 39, characterized in that said composition further comprises a drying agent.