FR2969157A1 - POLYMER COMPRISING A HYDROLYZABLE FUNCTION USEFUL AS FLUIDIFIER - Google Patents

Abstract

The present invention relates to a polymer comprising the following units: and side chains comprising R groups, its method of preparation and its uses as a fluidizer in hydraulic compositions.

Description

The present invention relates to a polymer, its method of preparation and its uses as a fluidizer in hydraulic compositions. [Prior art]

The hydraulic compositions are compositions comprising a hydraulic binder. A hydraulic binder is a binder that forms and hardens by chemical reaction with water. As hydraulic binders may be mentioned the compositions of plasters, sulphates and calcium aluminates, lime and cement. Mortars and concretes, especially prefabricated concretes and ready-mix concretes, are of particular importance. These materials may be intended in particular for building, civil engineering works or prefabrication. It is known to add to the hydraulic binders fluidifiers (also called plasticizers or superplasticizers) which make it possible to fluidify the hydraulic composition and thus to reduce the water content of the hydraulic binder paste. Thus, the hydraulic binder paste has, after hardening, a denser structure. This results in a higher mechanical strength. Particularly known are polyoxyalkylene polycarboxylates (PCP) particularly effective for fluidifying hydraulic compositions and also called superplasticizers. Recently, fluidizers have been developed to maintain an improved fluidity of hydraulic compositions over time. Fluidifiers having a structure evolving over time in fresh concrete have been developed. These fluidifiers are comb polymers whose side chains contain ester functions, which are hydrolysed under the basic conditions prevailing in the hydraulic compositions, releasing carboxylate functions over time. These carboxylate functions are capable of being adsorbed on the grains of hydraulic binder, in particular of cement, which induces a repulsion between the grains and thus makes it possible to maintain a good fluidity of the composition over time. Such fluidifiers are in particular described in US 2002/0007019 (Schober et al.), WO 2004/099099 (Nippon Shokubai) and EP 0 846 090 (Kao Corporation). [One technical problem] One of the objects of the invention is to provide compounds useful as fluidizers for improving the fluidity maintenance of hydraulic compositions over time more effectively than the prior art fluidifiers. According to a first aspect, the invention relates to a polymer comprising a main chain comprising units of formulas (A): R 3 R 4 -, 'CH2) p O- (N R6 (A) and side chains comprising R2 groups, where:

X represents O or NH,

R2 represents a group (R, O) ZR8, with:

R 2 represents a C 2 -C 3 alkylene group, R 8 represents H, an optionally substituted C 1 -C 12 alkyl, cycloalkyl or aryl, and

z represents an integer from 1 to 250

R3 and R4 independently represent H or methyl,

R6 represents H or a group R10i 2 R5 represents a hydrocarbon chain of 1 to 10 carbon atoms, a group (CH2) p-1 -CnH2n-NON-R6 (M) 11, a Rio group or a group O n represents a integer from 1 to 8, p represents 1 or 2, Rio represents a group - (CgH2q-O), - R11, or a group - (CgH2q-O), - (C = O) -R12, where: q represents an integer from 1 to 4, m represents an integer from 1 to 4, R11 represents H or a hydrocarbon chain of 1 to 10 carbon atoms, and R12 represents a hydrocarbon chain of 1 to 10 carbon atoms, and M represents a cation and c is an integer representing the valence of the cation M.

The polymer according to the invention comprises side chains comprising R2 groups. Each R2 group may be linked to the main chain of the polymer by: a single bond (the polymer may for example comprise vinyl groups bearing R2 group), a methylene group (the polymer may for example comprise R2 group-bearing allylic groups ), an amide function, an ester function (the polymer may for example comprise (alkyl) acrylate group R2 groups).

Generally, R2 groups are linked to the polymer backbone by ester functions, and the polymer typically comprises the following units of formulas (A) and (B): ## STR2 ## R4 + cc ± 0 = CC = 0 IOXI R5 CnH2n

JC H2) p in which:

X is O or NH, R3 and R4 are independently H or methyl,

R2 represents a group (R, O) ZR8, with:

R, represents a C2-C3 alkylene group,

R8 is H, optionally substituted C1-C12 alkyl, cycloalkyl or aryl, and z is an integer of 1 to 250,

R6 is H or R10,

R5 represents a hydrocarbon chain of 1 to 10 carbon atoms, a group (CH2) p-1 -CnH2n-N NR (M) 11, a group R10 or a group n represents an integer of 1 to 8, 15 represents 1 or 2, R10 represents a group - (CgH2q-O), - R11, or a - (CgH2q-O) group, r, - (C = O) -R12, where: q represents an integer of 1 to 4 m represents an integer from 1 to 4, R11 represents H or a hydrocarbon chain of 1 to 10 carbon atoms, and R12 represents a hydrocarbon chain of 1 to 10 carbon atoms, R110, R111 and R112 independently represent a group selected from H, alkyl, - COO-alkyl, COOR2 and COO (M) 1, c, and M represents a cation and c is an integer representing the valence of the cation M.

Advantageously, the hydraulic compositions comprising the abovementioned polymers have a good maintenance of fluidity over time, generally up to one hour, or even more than two hours, after mixing the components of the hydraulic composition. It is considered that the fluidity is maintained when the spreading value of the composition has decreased by less than 50%, especially less than 30%, preferably less than 10% from its initial value, just after preparation of the hydraulic composition. .

The polymer according to the invention has a structure evolving over time when it is added in the hydraulic compositions. Indeed, the units of formula (A) are hydrolyzed slowly under the basic conditions prevailing in the hydraulic compositions, thus releasing carboxylate functions. These carboxylate functions are capable of being adsorbed on the grains of hydraulic binder, which is supposed to contribute to maintaining a good fluidity of the hydraulic composition over time. It is called "hydrolysable pattern" from a "hydrolyzable monomer".

In addition to the units of formula (A) and side chains comprising R 2 groups of formula (R, O) ZR 8, the polymer may contain one or more units derived from monomers chosen from the following monomers: phosphonic ionic or ionizable monomer , sulfonic or carboxylic. Examples of phosphonic monomers are phosphoethyl methacrylate or monomethacrylates of polyethylene glycol phosphate esters, such as the monomers of the Sipomer PAM range marketed by Rhodia. Vinyl sulphonic acid and its salts, styrene sulphonic acid and its salts, 2-acrylamido-2-methylpropanesulphonic acid and its salts, allyoxyhydroxypropylsulphonic acid and its salts and methallylsulphonic acid and its salts may be used as sulfonic monomers. Examples of carboxylic monomers are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and crotonic acid. monomer comprising a polyalkylene glycol group, in particular polyethylene glycol (PEG), for example: polyalkylene glycol (meth) acrylate, in particular polyethylene glycol (PEG), the PEG acrylate monomers being advantageously used because of their hydrolysable nature in hydraulic compositions; polyalkylene glycol maleate, especially polyethylene glycol, polyalkylene glycol vinyl ether, especially polyethylene glycol, or polyalkylene glycol allyl, especially polyethylene glycol, in particular polyethylene glycol methyl ether allyl (of formula CH = CH-CH 2 - (OCH 2 -CH 2), - OMe), the molecular weight of which is for example between 100 and 10,000, preferably between 350 and 7000 and advantageously between 350 and 5000; and / or hydrolysable monomer, such as PEG acrylate or alkyl-PEG ether acrylates, acrylamide and its derivatives, acrylonitrile and its derivatives, alkyl acrylates such as acrylate ethylene, hydroxyalkyl acrylates such as hydroxyethyl acrylate, vinyl esters of carboxylic acids such as vinyl acetate, copolymerizable carboxylic anhydrides such as maleic anhydride or methacrylic anhydride, monomers with imide functions such as the maleimide and its derivatives. non-hydrolyzable monomer, such as styrene, alkyl methacrylates such as methyl methacrylate.

The aforementioned monomers are introduced into the polymer by copolymerization (incorporation in the main chain) or by postfunctionalization, in particular postesterification (incorporation into the side chains). The methods of preparation are described below.

The hydrolysable monomers (including the monomers corresponding to the units of formula (A)) generally represent from 5% to 95% by mole of all the monomers employed, preferably from 10% to 60% by mole of all the monomers used. monomers used.

Preferably, X represents O. In fact, when X represents O, the group-carrying O-chain (CH2) p-1 -CnH2n-NN-R6 is linked to the main chain by an ester function, which hydrolyzes generally. more easily than an amide function (when X represents NH) to form carboxylate functions, which make it possible to maintain a good fluidity of the hydraulic composition (as explained below).

Typically, R11o, R111 and R112 represent H or alkyl. Preferably, R110 and R111 are H and R12 is methyl.

In a preferred embodiment, the polymer comprises the following units of formulas (A), (B) and (C): R1 CH3 R3 R4 H1 CC ± + cc ± 2 C = 0 2 C = 0 0 = CC = 0 OOOX (M) 1 / c R2 R5 cl n1-12n N jCH2) p O ~ N R6 (C) (B) (A) in which:

X is O or NH, R1, R3 and R4 are independently H or methyl,

R2 represents a group (R, O) ZR8, with:

R, represents a C2-C3 alkylene group,

R8 is H, optionally substituted C1-C12 alkyl or cycloalkyl, or aryl, and z is an integer from 1 to 250,

R6 is H or R10,

R5 represents a hydrocarbon chain of 1 to 10 carbon atoms, a group (CH2) p-1 -CnH2n-N NR (M) 11, a group Rio or a group n represents an integer from 1 to 8, 15 represents 1 or 2, R10 represents a group - (CgH2q-O), - R11, or a group - (CgH2q-O), - (C = O) -R12, where: q represents an integer of 1 to 4, m represents an integer from 1 to 4, R11 represents H or a hydrocarbon chain of 1 to 10 carbon atoms, and R12 represents a hydrocarbon chain of 1 to 10 carbon atoms, M represents H or a cation and c is a number integer representing the valence of the cation M.

Preferably, the polymer consists of a sequence of the three aforementioned units without incorporation of other units, and therefore has the following formula (I): R 3 R 4 + CC 1+ 0 = CC = 0 1 0 X Ik 'R 5 CnH 2n in which : i, j and k independently represent an integer from 1 to 1000, k 'is an integer ranging from 1 to k, for each value of k', each of R5k 'independently represents a hydrocarbon chain of 1 to 10 atoms of carbon, a group (M) 1, c, a group R10 or a (CH2) p-1 -CnH2n-NON-R6 group 0 - M, c, R1, R2, R3, R4, R6, R10, X , n and p are as defined above.

In the context of this disclosure, "polymer" is understood to mean a compound comprising the covalent linking of monomeric units (or units) identical to or different from each other, generally of more than 10 monomeric units, typically of more than 100 monomer units. A copolymer comprises a covalent linking of at least two different types of patterns. As part of this disclosure, "side chain" or "pendant chain" means a chain covalently linked to the main chain of the polymer. For example, the COOR 2 and side groups of the polymer of the formula (I) are (CO 2) -1 COX -C n H 2 n -N-R 6. O are chains In the context of this disclosure, and unless otherwise stated, "hydrocarbon chain" means a chain comprising one or more carbon atoms and one or more hydrogen atoms, this chain being functionalized or non-functionalized, straight, branched or cyclic, saturated or unsaturated. The hydrocarbon chains present in a polymer according to the invention preferably comprise from 1 to 12 carbon atoms, preferably less than 6 carbon atoms. In the context of this disclosure, and unless otherwise stated, the alkyl groups represent monovalent saturated hydrocarbon chains, straight or branched chain or cyclic (for example a cyclohexyl radical), from 1 to 12 carbon atoms, preferably from 1 to 12 carbon atoms. 6 carbon atoms. Examples of alkyl radicals which may be mentioned include: when they are linear, the methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl radicals, when they are branched isopropyl, s-butyl, isobutyl and t-butyl groups.

In the context of this disclosure, and unless otherwise indicated, the alkylene radicals represent divalent saturated hydrocarbon radicals, straight or branched chain, of 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Methylene, ethylene and propylene radicals are particularly preferred. In the context of this disclosure, and unless otherwise stated, aryl radicals represent hydrocarbon aromatic systems, mono or bicyclic of 6 to 10 carbon atoms. Among the aryl radicals, there may be mentioned the phenyl or naphthyl radical. The alkyl, cycloalkyl and / or aryl groups are optionally substituted by one or more halogen groups, in particular fluorine, chlorine or bromine, in particular alkyl alkyl or alkoxy, in particular methoxy. A cation is an ion carrying a positive charge. Ammonium or metal cations, especially of alkali metal or alkaline earth metal, are preferred. The alkali metal cations are preferably Li +, Na +, K + and Cs +. The alkaline earth metal cations are preferably Cal + and Mg 2 +. An ammonium cation is a cation having a nitrogen atom carrying a positive charge. The ammonium cation corresponds to either the protonated form of an amine function, which may be primary, secondary, tertiary or aromatic, or to a quaternary ammonium cation, for example a tetraalkylammonium. The index "co" means that the arrangement of the consecutive units of the polymer is not specified. The arrangement of the units in the polymer may for example be block, alternating, statistical or composition gradient.

By "*" we mean that the different units can be assembled together

to others in any order, each unit being generally assembled from head to tail. The following preferred embodiments can be implemented in a combined or independent way:

X is O,

R3 and R4 represent H,

R7 represents an ethylene group,

R8 represents H, or a C1-C12i alkyl, especially a methyl or an ethyl, z represents an integer between 8 and 230, in particular between 15 and 115, typically 108,

R2 is a - (CH2-CH2-O) 108-Me group, obtainable by esterification with a poly (ethylene glycol) methyl ether of molecular weight of 4750 g / mol (MPEG 4750), i, j and k independently represent an integer from 1 to 100, R6 represents H, R5 or each of R5k 'independently of one another is an alkyl of 1 (CH2) p7-CnH2n-N1 / N-R6 to 10 carbon atoms, (M) 1, c or a group where n is 2, p is 1,

q represents 2,

R11 is H, methyl or ethyl, typically methyl,

R12 represents a methyl or an ethyl, typically a methyl,

The ratio i / (i + j + k) is from 0.01 to 0.8, in particular from 0.01 to 0.2, in particular from 0.02 to 0.05,

the ratio j / (i + j + k) is from 0.01 to 0.65, in particular from 0.2 to 0.5,

the ratio k / (i + j + k) is from 0.05 to 0.90, in particular from 0.3 to 0.7. Generally, the polymer comprises from 2 to 20% by weight, typically from 2 to 10% by weight of unit of formula (A). Preferably, the weight-average molecular weight of the polymer is 5,000 to 500,000 g / mol.

Preferably, the polymer according to the invention has the following formula (I '): ## STR2 ## in which: R 1, R 2, M, X, c, i, j, k and k 'are as defined above,

for each value of k ', Rk'15 represents an alkyl of 1 to 10 carbon atoms, C2H4 N ~ NH (M) 11 or a group O [Preparation method] According to a second aspect, the invention relates to a process for preparation of a polymer as defined above comprising a step a1) of copolymerization of a monomer of formula (XI '): 8110 8112 C = C 1 1 R111 C = 0

Wherein R 2, R 10, R 11, and R 11 are as defined above, with a monomer of the following formula (XII): R 5 R 4 C = C 10 = CC = O 1 OX 1 R 5 Wherein X, R3, R4, R5, R6, n and p are as defined above. The alkene functions of the two monomers react with one another to form the main chain of the polymer. The side chains of the formed polymer include (CH 2) pi COX-CnH 2n-N. N-R6 especially groups of formulas O and COO (R, O) ZR6. Other monomers may be added during step a1) of copolymerization, in particular those mentioned above, such as ionic or ionizable monomers of the phosphonic, sulfonic or carboxylic type, the monomers comprising a group

polyalkylene glycol, hydrolysable monomers and / or non-hydrolyzable monomers. The polymers are prepared according to the conditions known to those skilled in the art, in particular by following the procedures described in patent FR 2 892 420. The preparation process makes it possible in particular to prepare the polymer comprising the following units of formulas: CH3 H-± 2C = 0 0 = C Ç = 0

## STR2 ## using a polymerization of the monomers corresponding to the desired units or their precursors, if appropriate.

The process for the preparation of this polymer preferably comprises a step a1) of copolymerization of monomers of formulas (X), (XI) and (XII) as follows: R 1 H 2 C = CC = O (M) in which R 1, M 2 c are as defined above, 1 / c (X) wherein R 2 is as defined above, R 3 R 4 C = C 1 O = CC = O 1 OO 1 1 R 5 CnH 2n N-CH 2) p 0 NR wherein R3i R4, R5, R6, n and p are as defined above. The monomer (XII) used in step a1) can in particular be Cylink C4 from CYTEC, which is advantageously available commercially. Preferably, the monomer (XII) used in step a1) has the following formula (XII '):

H H 1 C = C 1 0 = C C = 0 1 0 0 -N

> 0 N (XII '). In another embodiment, the process for preparing the polymer 10 comprises the steps of: a2) copolymerizing a monomer of the following formula (XXII): ## STR2 ## (M 3) 1 / c 3 (M 3) 1 / c XXII) in which M3 is H, a metal cation or an ammonium cation and c3 is a

an integer representing the valence of the cation M3, and R3 and R4 are as defined above,

with a monomer of the following formula (XXI '): ## STR2 ## in which R116, R111 and R112 are as defined above and M2 represents H, a metal cation or an ammonium cation and c2 is an integer representing the valence of the cation M2,

b) esterifying the polymer obtained in step a2) with (CH2) p-1 GP2-CnH2n-NN-R6 compounds of formulas GP1- (R7O) ZR8i O and optionally GP3-R5 when R5 is different from ( M) 11, wherein R7, R8, z, n, p, R6 and R5 are as defined above and GP1, GP2 and GP3 are leaving groups, especially independently selected from -OH, -OTs, -OMs, In particular, the process comprises the steps of:

a2) copolymerizing monomers of the following formulas (X), (XXI) and (XXII): R1H2C = CC = O1O1 (M) 1 / c (X) in which R1i M and c are as defined above; above, 5 / c2 (XXI) wherein M2 is H, a metal cation or an ammonium cation and c2 is an integer representing the valency of the cation M2, R3 R4 CC OH ffO O (M3) 1 / c3 (M3) 1 in which M3 is H, a metal cation or an ammonium cation and c3 is an integer representing the valence of the cation M3, and R3 and R4 are as defined above, to obtain a polymer (XXV) comprising units of the following formulas: R 3 R 4 -CO 2 O 3 (M 3) 1 / c 3 (M 3) 1 / c 3 b) esterification of the polymer (XXV) with compounds of formulas GP1- (R7O) ZR8i ( Wherein R5 is other than (M) 11, wherein R7, R8, z, n, p, R6 and R5 are as defined above and GP1, GP2 and GP3 15 are departing groups, including independently cho isis among -OH, -OTs, -OMs, -Cl and -Br. In step b), compounds of formula R2-GP1 (or GP1- (R, O) ZR8), (CH2) p1 GP2-CnH2n-N1. N-R6 O and optionally GP3-R5 react from non-regioselective way with the carboxylic or carboxylate functions, which leads to the grafting (CH2) p1 -CnH2n-N .. N-R6 statistics of groups R2, R5 and O on the carboxylate or carboxylic functions of the polymer obtained at the end of the step a2), in particular of formula (XXV). Therefore, the polymer blend obtained at the end of step b) comprises the polymer as defined above. Thus, the first embodiment of the method (comprising step a1)) is preferred because it makes it possible to obtain the polymer with an improved purity compared to the second embodiment.

Preferably, the copolymerization step is carried out by radical polymerization, typically in the presence of an initiator and a transfer agent.

The initiator is, for example, hydrogen peroxide, a redox pair, the oxidizing agent being in particular ammonium persulfate and the reducing agent being in particular alkali metal metabisulfite, for example sodium, or a water-soluble azo initiator. for example, 2,2'-azobis (2-amidinopropane) dihydrochloride or 2,2'-azobis (2-methylpropionamide) dihydrate.

The transfer agent may especially be sodium methallyl sulfonate, 2-mercaptoethanol, mercaptoacetic acid, mercaptosuccinic acid or an alkyl mercaptan. The process can be performed batchwise or semi-continuously, and is preferably semi-continuous.

During the polymerization, the pH is generally adjusted between 1 and 3, preferably of the order of 2, according to methods known to those skilled in the art.

The temperature during the polymerization is generally 40 to 80 ° C, preferably 60 to 70 ° C.

Preferably, the preparation methods described above do not use lower alkyl acrylate monomers (especially methyl or ethyl acrylate) or lower hydroxyalkyl acrylates (especially 2-hydroxyethyl acrylate). , unlike the processes for the preparation of certain fluidifiers of the prior art. These monomers are difficult to use because of their low flash point (close to 2 ° C. and 15 ° C. for methyl and ethyl acrylate) or their toxicity in the case of 2-hydroxyethyl acrylate. In addition, the corresponding released alcohols are volatile (VOC) in the case of methanol and ethanol and / or toxic in the case of ethylene glycol and methanol. The monomers used in the preparation processes according to the invention are advantageously low in toxicity and have high flash points, which is advantageous in terms of safety. [Uses] According to a third aspect, the invention relates to the use of the polymer as defined above as a plasticizer (or plasticizer) for hydraulic compositions, in particular to improve the maintenance of fluidity of hydraulic compositions over time, usually up to one hour, or even more than two hours, after mixing the components of the hydraulic composition.

Without being bound by a particular theory, the good maintenance of fluidity can be explained by the specific structure of the polymers according to the invention, which changes over time in the hydraulic composition, which is an alkaline medium, generally pH inclusive between 11 and 13.

In fact, under these conditions, a gradual hydrolysis of the ester and / or side amide functions of the unit of formula (A) is observed: IR 3 R 4 O = CC = O 1 OX 1 R 5 CnH 2n R 6 (A) in the hydraulic composition, which generates over time: carboxylate functions on the polymer, capable of adsorbing on the grains of hydraulic binder, thereby creating a repulsion between the grains and thus maintaining a good fluidity of the hydraulic composition, (CH2) p-1 HO-CnH2n-N-R6 an alcohol of formula R5-OH and an alcohol of formula O when X represents 0, or an amine of formula (CH2) -1H2N-CnH2n-NON-R6O when X represents NH , which advantageously have high vapor pressures and therefore do not generate volatile organic compounds (VOCs) harmful to the environment and health, according to scheme 1 below. R 1 R 3 R 4 1+ 2 i = 0 2 i = 0 O 1 O-OOO 0 (M) R iic 2 R 5 C n H 2 n I-N-CH 2) p O N-1 R 6 R 1 CH 3 R 3 R 4 2 On the other hand, the ester function of the unit of formula (B): CH 3 + CC + H + 2 C = O 1 R.sub.2 alkaline medium, C.sub.2 = 0. Co O + R6 -N XH + R-OH (CH2) p (B) is stable in alkaline medium. It is therefore possible to modulate the hydrolysis of the polymer by varying the respective content of the different units in the polymer. It has been demonstrated that the maintenance of fluidity of a hydraulic composition comprising as adjuvant a polymer according to the invention is improved with respect to that of a hydraulic composition comprising as adjuvant a polymer free of hydrolysable lateral ester functions, in particular of formula ( W): ## STR2 ## wherein R 1, R 2, M, c, i and j are as defined above.

In addition, it has been demonstrated that the maintenance of fluidity of a hydraulic composition comprising as adjuvant a polymer according to the invention is improved with respect to that of a hydraulic composition comprising as adjuvant a polymer comprising ester-bearing functional units ester hydrolysable alkyl poly (ethylene glycol) ether ester of the following formula: + H2C-CH + O (CH2O) n Alkyl According to a fourth aspect, the invention relates to the use of a polymer as defined above for the preparation of a hydraulic composition comprising: a polymer as defined above, a hydraulic binder, - at least one granulate, and - water. co (W) 25

The hydraulic compositions may in particular be concrete, mortar or plaster.

The hydraulic compositions are prepared in a conventional manner by mixing the aforementioned constituents. The invention also relates to the process for preparing a hydraulic composition comprising the step of mixing: a polymer as defined above, a hydraulic binder, at least one granulate, water, the components being added in any order. The polymer according to the invention may be added to the other components of the dry hydraulic composition (generally in powder form) or in solution, preferably in aqueous solution. Thus, according to another aspect, the invention relates to a plasticizer (or plasticizer) for hydraulic compositions comprising the polymer as defined above in solution in a solvent, especially in aqueous solution, preferably from 5 to 50% by weight of polymer, especially from 10 to 30% by weight, in particular of the order of 20% by weight relative to the total weight of the solution. The water of said aqueous solution can in particular be the prewetting water. By "pre-wetting water" is meant a part of the total water, which is used to moisten the aggregates before mixing to simulate the hygrometric state of the aggregates, often wet, in a concrete plant or on site. Said aqueous solution comprising the polymer may optionally comprise other additives, for example an anti-foaming agent, an anti-entrainment additive, an accelerator or set retarder, a rheology modifying agent, another plasticizer (plasticizer or superplasticizer) and or any other additive conventionally used in hydraulic compositions. In a preferred embodiment, said aqueous solution comprising the polymer comprises a plasticizer, in particular a superplasticizer, for example a CHRYSO®Fluid Premia 180 or CHRYSO®Fluid Premia 196 superplasticizer.

By "aggregates" is meant a set of mineral grains with a mean diameter of between 0 and 125 mm. Depending on their diameter, aggregates are classified into one of six families: fillers, sand, sand, gravel, chippings and ballast (standard XP P 18-545). The most used aggregates are:

22 fillers, which have a diameter of less than 2 mm and for which at least 85% of aggregates have a diameter of less than 1.25 mm and at least 70% of aggregates have a diameter of less than 0,063 mm, sands of diameter included between 0 and 4 mm (in the standard 13-242, the diameter up to 6 mm), the bass of diameter greater than 6.3 mm, chippings of diameter between 2 mm and 63 mm. Sand is therefore included in the definition of granulate according to the invention. The fillers can in particular be of calcareous or dolomitic origin.

During the mixing step, other additives may be added, for example a mineral addition and / or additives, for example an anti-air entrainment additive an antifoaming agent, an accelerator or retarding agent, an agent rheology modifier, another plasticizer (plasticizer or superplasticizer), especially a superplasticizer, for example a CHRYSO®Fluid Premia 180 or CHRYSO®Fluid Premia 196 superplasticizer. "Mineral addition" means a finely divided mineral material used in concrete to improve certain properties or to confer particular properties. The NF EN 206-1 standard distinguishes two types of mineral additions: almost inert additions (type I) and additions of a pozzolanic or latent hydraulic nature (type II). The additions of type I are: calcareous fillers, in accordance with EN 12620: 2000 pigments, in accordance with EN 12878 limestone additions, in accordance with standard NF P 18-508, siliceous additions, in accordance with the NF standard P 18-509 Additions of type II include: fly ash, compliant with standard NF EN 450 silica fumes, in accordance with EN 13263-1

Generally, 0.1 to 3%, especially between 1.0 and 2.0%, by weight of dry extract, of polymer according to the invention are used in the hydraulic composition.

According to a fifth aspect, the invention relates to a hydraulic composition comprising: a polymer according to the invention as defined above,

23 a hydraulic binder, a granulate, water. The hydraulic composition may further comprise the aforementioned additives.

The invention also relates to a method of improving the maintenance of fluidity over time of a hydraulic composition comprising a step of bringing into contact a hydraulic composition or a component of a hydraulic composition with a polymer as defined above . The constituents of a hydraulic composition are in particular those mentioned above.

[Figure] The attached figure shows the spread in mm versus time in minutes of mortar compositions of Example 2 comprising: either the polymer (A) of the comparative example (diamonds) or the polymers (Cl) and (C2) of Comparative Example 2 (respectively triangles and circles), ie the polymer (B) according to the invention of Example 1 (squares). [Example]

Comparative Example: Synthesis of a polymer of formula (A) free of hydrolysable side chain O 108 Me (A) H25 In a glass reactor, equipped with a mechanical stirrer and a condenser, was introduced at the bottom of tank an aqueous solution (231 g) containing a mixture of sodium methallyl sulfonate (1.4 g) (ALTICHEM) and sodium metabisulphite (3.1 g) (ALTICHEM). The pH of the mixture was adjusted to 2 by moderate addition of 96% sulfuric acid (0.4 g) (ALTICHEM). The mixture was kept under vigorous stirring and under strong nitrogen bubbling for 1 h and brought to a temperature of 65 ° C. Aqueous solution (100 g) containing ammonium persulfate (3.7 g) (ALTICHEM) and a solution containing MPEG 4750 methacrylate (642.1 g) (CHRYSO) and a solution containing methacrylic acid (18.5 g) (EVONIK). The addition times were 3 h for the monomer mixture and 4 h for the ammonium persulfate solution. After stirring for one hour at 65 ° C., the reaction mixture was cooled to 20 ° C. and diluted with water to a level of 20% solids.

Comparative Example 2 Synthesis of Polymers of Formulas (Cl) and (C2) Comprising a Hydrolyzable Side Chain of Alkyl Polyethylene Glycol Ether Ester Type

Polymer (C1) comprising a hydrolysable side chain of the MPEG350 acrylate type; After stirring and a condenser, an aqueous solution (350 g) containing a mixture of sodium methallyl sulfonate (1.14 g) (ALTICHEM) and sodium metabisulphite (1.72 g) was introduced at the bottom of the tank. ) (ALTICHEM). The pH of the mixture was adjusted to 2 by moderate addition of 96% sulfuric acid (0.9 g). The mixture was kept under vigorous stirring and under strong nitrogen bubbling for 1 h and brought to a temperature of 65 ° C. Then, in parallel, an H co (Cl) was added

Aqueous solution (100 g) containing ammonium persulfate (1.3 g) (ALTICHEM) and a solution containing MPEG 4750 methacrylate (506 g), methacrylic acid (1.6 g) (EVONIK) and MPEG 350 acrylate (47.4g) (Sartomer CD551). The addition times were 3 h for the monomer mixture and 4 h for the ammonium persulfate solution. After stirring for one hour at 65 ° C., the reaction mixture was cooled to 20 ° C. and diluted with water to a level of 20% solids.

Polymer (C2) comprising a hydrolysable side chain of the MPEG550 acrylate type (C2) In a glass reactor, equipped with a mechanical stirrer and a condenser, was introduced at the bottom of the tank an aqueous solution (290 g) containing a mixture of sodium methallyl sulfonate (0.99 g) (ALTICHEM) and sodium metabisulfite (1.49 g) (ALTICHEM). The pH of the mixture was adjusted to 2 by moderate addition of 96% sulfuric acid (0.9 g). The mixture was kept under vigorous stirring and under strong nitrogen bubbling for 1 h and brought to a temperature of 65 ° C. An aqueous solution (100 g) containing ammonium persulfate (1.79 g) (ALTICHEM) and a solution containing methacrylate of MPEG 4750 (438 g) (CHRYSO), which was then added, was then added in parallel. methacrylic acid (0.7 g) (EVONIK) and MPEG 550 acrylate (66.3 g) (Sartomer CD278). The addition times were 3 h for the monomer mixture and 4 h for the ammonium persulfate solution. After stirring for one hour at 65 ° C., the reaction mixture was cooled to 20 ° C. and diluted with water to a level of 20% solids.

EXAMPLE 1 Synthesis of a Polymer According to the Invention Comprising Hydrolyzable Side Chains of Formula (B): ## STR2 ## in which R '5 represents H or O according to the units. In a glass reactor, equipped with mechanical stirring and a condenser, was introduced at the bottom of the tank an aqueous solution (326.3 g) containing a mixture of sodium methallyl sulfonate (0.9 g) ( ALTICHEM) and sodium metabisulfite (1.3 g) (ALTICHEM). The pH of the mixture was adjusted to 2 by moderate addition of 96% sulfuric acid (0.5 g). The mixture was maintained under vigorous stirring and under strong nitrogen bubbling for 1 h and brought to a temperature of 65 ° C. An aqueous solution (100 g) containing ammonium persulfate (1.6 g) (ALTICHEM) and a solution containing methacrylate of MPEG 4750 (531 g) (CHRYSO), which was then added, was then added in parallel. methacrylic acid (0.5 g) (EVONIK) and Cylink C4 (54.2 g) (CYTEC), which is a mixture of the following two monomers: HHHHC = C 0 = CC = 0 CCC = 0 0 = C 1 1 O 0 0 OH C2H4 C2H4 C2H4 26 HHI + -] 2C = 0 0 = CC = 0 II 01 OO 1 R'5 C2H4 CH2

CH2 N

The addition times were 3 hours for the monomer mixture and 4 hours for the ammonium persulfate solution After stirring for 1 hour at 65 ° C. C, the reaction mixture was cooled to 20 ° C and diluted in water to 20% solids.

Example 2: Use of Polymers (A), (B), (Cl) and (C2) as Fluidifiers Dispersants at 20% solids (consisting of a mixture of polymers (A), (B), (Cl) or (C2) at 20% in water) were evaluated by a measure of workability on mortar . The composition of the mortar was that of Table 1: Component mass (g) EMC 152.5 N LE HAVRE 624.9 Filler limestone ERBRAY 412.1 Sand AFNOR 1350 Fulchiron (corrector sand) 587 Total water 375 Table 1: Composition of the mortar

Workability was evaluated by measuring the slump flow diameter (diameter of the formed puddle after flow) as follows. A frustoconical, 0.5-scale reproduction mold of the Abrams cone (see standard NF 18-451, 1981) was filled with the following dimensions: diameter of the top base circle 5 cm diameter After mixing the mortar containing the polymer, the mold was filled, the upper surface of the cone was then leveled, then the cone was lifted vertically and the spreading was measured. 90 ° with a tape measure. The result of the spread measurement is the average of the 2 values at + 1-10 mm. The tests were repeated at different times at 5, 30, 60, 90 and 120 minutes in 2 diameters. The tests were carried out at 25 ° C.

The percentages by weight of polymer (A), (B), (Cl) or (C2) dry were adjusted to obtain an initial spreading value of 250 ± 20 mm. Thus, respectively 0.5%, 2.2%, 2.2% and 2.5% of polymer (A), (B), (Cl) or (C2) by dry weight were used in the mortar. The dose of polymer (B), (Cl) or (C2) to be used is therefore greater than the polymer dose (A), which can be explained by the fact that initially (before hydrolysis of the ester functions) the polymers (B), (C1) and (C2), comprising hydrolysable monomers, comprise in less proportion carboxylate functions capable of binding to the grains of hydraulic binder than the polymer (A). The percentages by weight of polymers (C1) and (C2) by dry extract are of the same order of magnitude, which is explained by the chemical structures are close to these two polymers.

The evolution of the spread over time is illustrated in the attached figure.

These results show that the maintenance of fluidity over time is significantly improved when the polymer (B) according to the invention is used. The fluidity is maintained at least two hours after mixing the constituents of the mortar, while it drops significantly with the other three polymers during the first hour.

EXAMPLE 3 Formulation of the Polymer (B) with the Superplasticizer CHRYSO®Fluid Premia 196

Example 2 was reproduced by adding a CHRYSO®Fluid Premia 196 superplasticizer to the composition in addition to the polymer (B) according to the invention. The percentages by weight of polymer (B) and CHRYSO®Fluid Premia 180 were adjusted so as to obtain an initial spreading value of 250 mm ± 20 mm. Thus 1% of the polymer mixture (B) and CHRYSO®Fluid Premia 180 in dry weight were used in the mortar. The dose of the mixture of the two polymers is lower than that of the polymer (B) used alone (cf. Example 2), which can be explained by a greater water-reducing nature of CHRYSO®Fluid Premia 196 making it possible to lower the overall dosage. The evolution of the spread over time is described in Table 2 below: Ta 29 Spread (mm) Time Blend Polymer (B) + (min) CHRYSO®Fluid Premia 196 (1%) 235 30 180 60 165 90 150 120 110 bleau 2: Evolution of the spreading during terr ps

Claims (18)

CLAIMS A polymer comprising a main chain comprising units of the formula R 3 R 4 + C-C 0 = CC = O IIOX 1 R 5 CnH 2 n N CHCH 2) PO ~ where: X represents O or NH, R2 represents a group (R, O) ZR8, where R, is C 2 -C 3 alkylene, R 8 is H, optionally substituted C 1 -C 12 alkyl, cycloalkyl or aryl, and z is an integer of 1 to 250, R 3 and R4 are independently H or methyl, R6 is H or R10, R5 is a hydrocarbon chain of 1 to 10 carbon atoms, a group (CH2) p-1 -CnH2n-NON-R6 (M) 11, a group R10 or a group O n represents an integer from 1 to 8, p represents 1 or 2, R10 represents a group - (CgH2q-O), - R11, or a group - (CgH2q-O), - (C = 0) -R12, where: q represents an integer of 1 to 4, m represents an integer of 1 to 4, R11 represents H or a hydrocarbon chain of 1 to 10 carbon atoms, and N R6 (A) and side chains comprising R2, - R12 represents a hydrocarbon chain of 1 to 10 carbon atoms, and M represents a cation and c is an integer representing the valence of the cation M. 2. The polymer according to claim 1, comprising units of the following formulas (A) and (B): (B) R 3 R 4 + CC + O = CC = O 10 OX R 5 CnH 2 n N-CH 2) p in which: X, R2, R3, R4, R5, R6, n, p and M are as defined in claim 1, R11o, R111 and R112 independently represent a group selected from H, alkyl, - COO-alkyl, COOR2 and COO (M )1 C. 3. Polymer according to claim 2, comprising units of the following formulas (A), (B) and (C): R1 CH3 R3 R4 + -] + ft] + ft] 2 C = 0 2 C = 0 0 = In which: X, R2, R3, R4, R5, R6, n and p are as defined in claim 1, 5R, (C) wherein is H or methyl, M is H or a cation and c is an integer representing the valence of the cation M. 4. Polymer according to claim 3, of formula (I) below: R 3 R 4 + C-C 1 + 0 = C C = O 1 O X 1. In which: i, j and k independently represent an integer from 1 to 1000, k 'is an integer ranging from 1 to k, for each value of k', each of R5k 'independently represents a hydrocarbon chain of 1 to 10 carbon atoms, a group (M), a group R, o or a (CH2) p1 -CnH2n -NN-R6 group OM, c, R1, R2, R3, R4, R6, R, o, X, n and p are as defined in claim 3. Polymer according to any one of claims 1 to 4, wherein R5 or each of R5k 'independently of one another is an alkyl of 1 to 10 carbon atoms, (M)' c as defined in the claim Or a (CH 2) -1 -C n H 2 n -N / N-R 6 O group, wherein n, p and R 6 are as defined in claim 2. 6. Polymer according to any one of claims 1 to 5, wherein R6 represents H. Polymer according to any one of claims 4 to 6, wherein: the ratio i / (i + j + k) is from 0.01 to 0.8, and / or the ratio j / (i + j + k) is from 0.01 to 0.65, and / or the ratio k / (i + j + k) is from 0.05 to 0.90. 8. Polymer according to any one of claims 1 to 7, comprising from 2 to 10% by weight of unit of formula (A). 9. Polymer according to any one of claims 1 to 8, with a molecular weight of 5000 to 500 000 g / mol. 10. The polymer according to any one of claims 1 to 9, wherein the polymer has the following formula (1 '): co (1') in which: R1i R2, M, X, c, i, j, k and k 'are as defined in claim 4, for each value of k', Rk'15 represents an alkyl of 1 to 10 carbon atoms, C2H4 N ~ NH (M) 11 or a group O R2 HH 1 CC ~ Jk 0 = CC = 0 OX Ik 'R15 C2H4 11. A process for preparing a polymer according to any one of claims 2 to 10 comprising a step a1) copolymerization of a monomer of formula (XI '): 110 1112 C = C 1 1 R111 C = 0 In which R2, R110i R111 and R112 are as defined in claim 2, with a monomer of the following formula (XII): C = C 0 = CC = O 1 OX R5 CnH2n O Wherein X, R3, R4, R5, R6, n and p are as defined in claim 2. 12. Preparation process according to claim 11 comprising a step a1) 10 of copolymerization of monomers of formulas (X), (XI) and (XII) as follows: R 1 H 2 C = CC = 0 1 O 1 (M) 1 / c ( X) wherein R1i M and c are as defined in claim 3, wherein R 2 is as defined in claim 3, O- (N R6) (XII) wherein R3, R4, R5, R6, n and p are as defined in claim 3. 13. A process for the preparation of a polymer according to any one of claims 2 to 10, comprising the steps of: a2) copolymerizing a monomer of the following formula (XXII): R 4 CC OH ffO O (M 3) 1 / c 3 (M3) 1 / c3 (XXII) wherein M3 is H, a metal cation or an ammonium cation and c3 is an integer representing the valence of the cation M3, and R3 and R4 are as defined in claim 2, with a monomer of the following formula (XXI '): ## STR5 ## wherein R116, R111 and R112 are as defined in claim 2. and M2 represents H, a metal cation or an ammonium cation and c2 is an integer representing the valence of the cation M2, b) esterification of the polymer obtained in step a2) by compounds of (CH2) -1 GP2-CnH2n -N \ / N-R6 formulas GP1- (R7O) ZR8i O and optionally GP3-R5 when R5 is other than (M) 11, wherein R7, R8, z, n, p, R6 and R5 are such that defined in claim 2 and GP1, GP2 and GP3 are leaving groups, especially independently selected from -OH, -OTs, -OMs, -Cl and Br. 14. Preparation process according to claim 13, comprising the steps of: a2) copolymerizing monomers of the following formulas (X), (XXI) and (XXII): R1H2C = CC = O1O (M) - / c (X) in which R1, c and M are as defined in claim 3, wherein CH3 H2C = CC = OO (M2) R110 R112 CC1 1 R111 C = O (M2) 1 / c2 1 / c2 ( XXI) in which M2 is H, a metal cation or an ammonium cation and c2 is an integer representing the valence of the M2 cation, R3 R4 CC OH ffo OO (M3) 1 / c3 (M3) 1 / c3 (XXII) in wherein M3 is H, a metal cation or an ammonium cation and c3 is an integer representing the valence of the cation M3, and R3 and R4 are as defined in claim 3, to obtain a polymer (XXV) comprising following formulas: (M2) 1 / c2 R3 74 + C-C + OH ffO 01 (M3) 1 / c M3) / c2 (XXV) b) esterification of the polymer (XXV) with compounds of formulas GP1- (R7O) ZR8i (CH2) p GP2-CnH2n-NN-R6 O and optionally t GP3-R5 when R5 is different from (M) 11, wherein R7, R8, z, n, p, R6 and R5 are as defined in claim 3 and GP1, GP2 and GP3 are leaving groups, especially independently selected from -OH, -OTs, -OMs, -Cl and -Br. 15.- Use of the polymer as defined in any one of claims 1 to 10 to improve the maintenance of fluidity of hydraulic compositions. 16. A fluidizer for hydraulic compositions comprising the polymer as defined in any one of claims 1 to 10 in solution in a solvent, especially in aqueous solution, preferably comprising from 5 to 50% by weight of said polymer, relative to to the total weight of the solution. 17. A hydraulic composition comprising: a polymer as defined in any one of claims 1 to 10, a hydraulic binder, a granulate, water. 18.- hydraulic composition according to claim 17, wherein the hydraulic composition is concrete, mortar or plaster.