FR3033787A1 - USE OF COPOLYMERS FOR IMPROVING MECHANICAL RESISTANCE TO YOUNG PEOPLE OF A HYDRAULIC COMPOSITION - Google Patents

Abstract

The invention relates to the use, for increasing the mechanical strength at young ages of a hydraulic composition, of at least one copolymer obtained by polymerization from a monomer mixture comprising: at least one anionic monomer (a) comprising a polymerizable unsaturated functional group and a carboxylic group and - at least one monomer (b) of the following formula (I): H 2 C = C (- R 1) - (CH 2) p - O - [(EO) n - (PO) m ] - H (I) in which: R1 represents a hydrogen atom or a CH3 group, p is 1 or 2, [(EO) n - (PO) m] represents a polyalkoxylated chain consisting of ethoxylated units EO and d propoxylated units PO, divided into blocks, alternating or statistic and m and n represent integers varying between 1 and 250, the sum of m and n being greater than or equal to 10, provided that the molar proportion of the ethoxylated units in the chain polyalkoxylated (n) / (m + n) is strictly less than 90%.

Description

TECHNICAL FIELD The present invention relates to the field of hydraulic compositions, such as concrete and mortar compositions. More particularly, it relates to the use of specific copolymers for improving the mechanical strength properties at young ages of hydraulic compositions. Such hydraulic compositions are intended for all construction markets.

The hydraulic compositions generally comprise various chemical additives for modulating their properties. Among these, the so-called "water-reducing agents", also known as "dispersing agents", "fluidizing agents", "plasticizing agents" or "superplasticizers", are well known and have been used for many years. These dispersants lead to a decrease in the water content of the hydraulic compositions, which makes it possible to improve the performance of these compositions and in particular their mechanical strength. For example, comb-type carboxylic polymers have been developed as dispersants. In general, these polymers have a skeleton generally of (meth) acrylic nature and side chains terminated by hydrophilic groups, for example polyoxyalkylated side groups. CN 1148329C thus proposes, as dispersing agents for cements, copolymers obtained by polymerization from a monomer of the monocarboxylic acid type, such as (meth) acrylic acid, and an ether-type monomer. polyalkylene glycol in which the proportion in ethoxylated units is at least 90 mol% of all the alkoxylated units, preferably a polyethylene glycol ether. On the other hand, the workability of the compositions, for example concrete compositions, increases with their water content. However, it is essential to have good maneuverability or initial fluidity of the hydraulic composition, for example concrete, insofar as this property conditions its implementation, for example for filling a formwork. The maneuverability can be evaluated by measuring the slump (or "slump" in English) according to EN 12350-2.

Therefore, it is generally sought, when formulating a hydraulic composition, to achieve a compromise between the mechanical properties and the workability of the hydraulic composition. Better mechanical strength is one of the properties particularly sought after in the evaluation of hydraulic compositions. The measurement of the mechanical strength of the hydraulic compositions can be carried out at different times, for example at 1 day, 7 days or 28 days, the time TO corresponding to the preparation of the hydraulic composition. In the context of the present invention, particular attention is given to the mechanical strength at young ages. High mechanical strength at young ages is particularly desirable in the case of concreting to be carried out in cold weather or for quick stripping on site. This property of "early age strength," also referred to as "1 day compressive strength," is defined as the change in compressive strength as a function of the age of preparation of the hydraulic composition, in 15 zone TO at T = 1 day following the preparation of the hydraulic composition. The present invention aims precisely to improve the resistance to young ages, including 1 day, hydraulic compositions without altering their fluidity or initial handling. It thus relates, according to a first of its aspects, the use to increase the mechanical strength at young ages, especially to 1 day, of a hydraulic composition, of at least one copolymer obtained by polymerization from a mixture monomer composition comprising: at least one anionic monomer (a) comprising a polymerizable unsaturated functional group and a carboxylic group and at least one monomer (b) of the following formula (I): H 2 C = C (-R 1) - (CH 2) p - 0 - [(E0) .- (P0) .1 - H (I) wherein: R1 represents a hydrogen atom or a CH3 group, p is 1 or 2, [(E0). - (P0) .1 represents a polyalkoxylated chain consisting of ethoxylated units EO and propoxylated units PO, divided into blocks, alternating or statistical and m and n represent integers varying between 1 and 250, the sum of m and n being greater than or equal to 10, provided that the molar proportion of the ethoxylated units in the polyalkoxylated (n) / (m + n) chain is strictly less than 90%. The copolymers used according to the invention, as defined above, comprising at least units derived from the anionic monomers (a) and units derived from the monomers (b) of the formula (I), are designated more simply in the rest of the text under the name "copolymers according to the invention". In the context of the present invention, the "early age" mechanical resistance refers more particularly to the compressive strength at 24 hours (± 15 minutes) after the preparation of the hydraulic composition. The compressive strength at 1 day can be measured according to EN 12390-3. By "improving" or "increasing" the mechanical strength at young ages, is meant more particularly, in the context of the invention, the fact of accessing by the implementation of the copolymer according to the invention as an adjuvant in a hydraulic composition an increase in compressive strength to 1 day (measured according to EN 15 12390-3) of at least 4%, in particular of at least 4.5%, in particular by at least 10%, preferably at least 15% and more preferably at least 20%, in comparison with the resistance value obtained with the use as adjuvant in the same hydraulic composition of a copolymer, not according to the invention, of similar composition with the exception that the polyalkoxylated chain of monomeric units of type (b) is a polyethylene glycol chain (100 mol% in ethoxylated units EO). The use of copolymers according to the invention allows the faster development of the mechanical strength at young ages of the hydraulic compositions that incorporate them. In other words, such copolymers make it possible to improve the short-term mechanical strength ("at young ages"), particularly at 1 day, of the hydraulic compositions in which they are used. As illustrated in the examples which follow, the copolymers according to the invention advantageously make it possible to obtain strengths at young ages, particularly at 1 day, elevated.

More particularly, the use of a copolymer according to the invention in a hydraulic composition, for example a concrete composition, makes it possible to obtain a compressive strength at 1 day (measured according to the EN 12390-3 standard). the adjuvanted hydraulic composition according to the invention greater than or equal to 155% of the value of the resistance of the hydraulic composition lacking copolymer according to the invention. In particular, the compressive strength at 1 day may be greater than or equal to 160%, in particular greater than or equal to 170%, or even greater than or equal to 180% of the value of the resistance of the copolymer-free hydraulic composition according to US Pat. 'invention.

The use of the copolymers according to the invention proves, for example, particularly advantageous for concreting. The increase in the short-term mechanical strengths of the hydraulic composition, for example concrete, also allows faster demolding and stripping. Furthermore, advantageously, this increase in mechanical strength at young ages is not at the expense of other performance of the hydraulic composition, including its fluidity or initial handling. Other characteristics, advantages and modes of application of the implementation of the copolymers according to the invention will emerge more clearly on reading the description and the example which will follow, given by way of illustration and not limitation. In the remainder of the text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and mean to mean that terminals are included unless otherwise stated. Unless otherwise indicated, the phrase "comprising / including a" must be understood as "comprising / comprising at least one". COPOLYMERES ACCORDING TO THE INVENTION As indicated above, the present invention uses copolymers obtained by polymerization from at least one or more anionic monomer (s) comprising a polymerizable unsaturated functional group and a carboxylic group. noted (s) "monomer (s) (a)" in the following text and - one or more monomer (s) of formula (I) below, noted (s) "monomer (s) (b)" in the following of the text, wherein: R 1 represents a hydrogen atom or a CH 3 group, p is 1 or 2, 3033787 RE0). - (P0) .1 represents a polyalkoxylated chain consisting of ethoxylated units E0 and propoxylated units PO, divided into blocks, alternating or statistical and m and n represent integers varying between 1 and 250, the sum of m and n being Greater than or equal to 10, provided that the molar proportion of the ethoxylated units in the polyalkoxylated (n) / (m + n) chain is strictly less than 90%. The copolymers used according to the invention may optionally comprise other polymerizable monomers. The optional monomers possibly entering into the composition of a copolymer according to the invention may be of various natures, as detailed in the rest of the text. In particular, said anionic monomers (a) and said monomers (b) of formula (I) may represent more than 80 mol%, in particular more than 90 mol%, and more particularly more than 95 mol% of the total number of mol of monomers constituting the copolymer. According to an alternative embodiment, the copolymer used according to the invention consists solely of units derived from the monomers (a) and (b). In other words, the copolymer can be obtained by polymerization from a monomer mixture of one or more anionic monomer (s) (a) and one or more monomer (s) (b) of formula (I). The distribution of the units deriving from the monomers (a) and those deriving from the monomers (b) in the copolymer according to the invention can be of block, alternating or statistical type. According to one embodiment, it is a statistical or alternating distribution. According to another embodiment, it is a block-type distribution.

Anionic monomer (a) having a polymerizable unsaturated functional group and a carboxylic group. The anionic monomers (a) used in the composition of the copolymer used according to the invention may be more particularly chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and mixtures of these monomers. The monomer or monomers (a) may be in acid form, for example carboxylic acid and / or salt form, for example carboxylate. It is understood that a single or a mixture of several different monomers (a) can enter into the composition of the copolymer according to the invention. For example, it may be a mixture of acrylic acid monomers and methacrylic acid monomers or a mixture of monomers of maleic acid, acrylic acid and methacrylic acid. According to one particular embodiment, the copolymer used according to the invention is formed from at least acrylic acid and / or methacrylic acid, in particular at least acrylic acid (AA). . According to an alternative embodiment, the at least one anionic monomer (s) (a) used in the composition of the copolymer used according to the invention are chosen from acrylic acid, methacrylic acid and their mixture.

According to one particular embodiment, said anionic monomer (s) (a) may represent from 50% to 99% by mole, in particular from 60% to 95% by mole, in particular from 70% to 95% by mole. and more particularly from 80% to 90% molar of the total number of moles of constituent monomers of the copolymer according to the invention.

Monomer (b) of formula (I) As indicated above, the monomers (b) used in the composition of the copolymer used according to the invention correspond to the following formula (I): H 2 C = C (-R 1) - ( CH2) p - 0 - [(E0). - (PO) m] - H (I) in which: R1 represents a hydrogen atom or a group CH3, p is 1 or 2, [(E0). - (PO) m] represents a polyalkoxylated chain consisting of ethoxylated units EO and propoxylated units PO and m and n represent integers varying between 1 and 250, the sum of m and n being greater than or equal to 10, under reserve that the molar proportion of the ethoxylated units in the polyalkoxylated chain (n) / (m + n) is strictly less than 90%. By "polyalkoxylated" chain is meant a chain of poly (alkylene glycol) type. By "poly (alkylene glycol)" is meant a polymer of an alkylene glycol derived from an olefinic oxide. The poly (alkylene glycol) chain of the monomer (b) is formed of ethoxylated units (or "ethylene-oxy"), denoted "E0", of formula -CH2-CH2-O- and propoxylated units (or "propylene"). -oxy "), denoted" P0 ", of formula -CH2-CH (CH3) -O-.

The schematic representation "[(E0) - (PO) m]" in no way assumes the order of the ethoxylated and propoxylated units of the polyalkoxylated chain. In fact, the polyalkoxylated chain may have a distribution of units E0 and PO block type, statistical or alternating.

According to a particular embodiment, the units E0 and PO are divided into blocks. In particular, the polyalkoxylated chain of the monomer (b) may be of diblock type and be formed of a polyoxyethylene block and a polyoxypropylene block. According to one embodiment variant, p in formula (I) above is 1. In other words, according to this variant embodiment, the monomer (s) (b) used in the composition of the copolymer according to the invention correspond to the following formula (I '): H2C = C (- Ri) - CH2 - 0 - RE0). - (PO) m] - H (I ') in which R 1, n and m are as defined above. According to a particular embodiment, the copolymer used according to the invention is formed from at least one monomer (b) of formula (I) or (I ') above, in which R 1 represents a methyl group. In particular, according to a particular embodiment, the copolymer used according to the invention is obtained from at least one monomer (b) of the following formula (II): H 2 C = C (-CH 3) -CH 2 0 - RE0). Where m and n are as defined above. As indicated above, the schematic representation "[(E0). - (PO) m] "in no way presumes the order of the ethoxylated and propoxylated units of the polyalkoxylated chain. The polyalkoxylated chain may have a distribution of units E0 and 25 PO block type, statistical or alternating, in particular blocks. According to a particular embodiment, the copolymer used according to the invention is obtained from at least one monomer (b) of the following formula (III): CH m and n being as defined previously.

In the aforementioned formula (III), the polyalkoxylated chain is formed of a first polyoxyethylene block and a second polyoxypropylene block. According to another embodiment variant, p in formula (I) above is equal to 2. In other words, according to this variant embodiment, the monomer (s) (b) used in the composition of the copolymer according to the invention correspond to the following formula (I "): H2C = C (-R1) -CH2-CH2 -O-RE0). (PO) m1-H (I") in which R1, n and m are as defined above. According to one particular embodiment, the copolymer used according to the invention is formed from at least one monomer (b) of formula (I ") above, in which R 1 represents a methyl group. a particular embodiment, the copolymer used according to the invention is formed from at least one monomer (b) of formula (IV): H 2 C = C (-CH 3) -CH 2 -CH 2 -O- RE0) .- (PO) m] - H (IV) in which n and m are as defined above As previously indicated, the schematic representation "[(E0) .- (PO) m]" does not assume that the order of the ethoxylated and propoxylated units of the polyalkoxylated chain The polyalkoxylated chain may have a distribution of units E0 and 20 PO of the block type, random or alternating, in particular of the block type According to a particular embodiment, the copolymer according to the invention is obtained from at least one monomer (b ) of formula (V) below: H2C = C (-CH3) -CH2-CH2-O- (E0) .- (PO) m -H (V) m and n being as defined previously.

In the aforementioned formula (V), the polyalkoxylated chain is formed of a first polyoxyethylene block and a second polyoxypropylene block. As for the anionic monomers (a), it is understood that a single or a mixture of several different monomers (b) can enter into the composition of the copolymer used according to the invention.

Thus, according to a particular embodiment, the copolymer according to the invention is obtained from at least one mixture of at least one monomer (bi) of formula (I) in which R 1 represents a hydrogen atom and at least one monomer (b2) of formula (I) in which R1 represents a methyl group.

In particular, the copolymer according to the invention can be obtained from at least one mixture of at least one monomer (bi ') of formula (I') above, in which R 1 represents a hydrogen atom and at least one monomer (b2 ') of formula (I') above, in which R1 represents a methyl group (in other words, a monomer 5 (b2 ') of formula (II) above). In the context of this particular embodiment, the monomer (s) (bi ') and the monomer (s) (b2') used in the composition of the copolymer according to the invention can be used in a molar ratio monomer (s) (bi ') / monomer (s) (b2') ranging from 10 to 0.01, in particular from 1 to 0.1.

According to yet another particular embodiment, the copolymer according to the invention can be obtained from at least one mixture of at least one monomer (bi ') of formula (I') above and at least one monomer (b2 ") of formula (I") above. In particular, the copolymer according to the invention can be obtained from at least one mixture of at least one monomer (bi ') of formula (I') above wherein R 1 represents a methyl group (in other words, a monomer (bi ') of formula (II) above) and at least one monomer (b2 ") of formula (I") above in which R1 represents a methyl group (in other words, a monomer (b2 ") of formula ( According to an essential characteristic of said monomer (s) (b) used in the composition of the copolymer according to the invention, the molar proportion of the ethoxylated units EO in the polyalkoxylated chain (that is to say (n) / (m + n) in formula (I), (I '), (II) or (III) above) is strictly less than 90%, according to a particular embodiment, the molar proportion of the ethoxylated units. EO in the polyalkoxylated chain is greater than or equal to 70%, in particular the molar proportion of EO ethoxylated units in the polyalkoxylated chain may be between 70% and 88%, in particular be greater than or equal to 72%, and more particularly greater than or equal to 75%. According to a particular embodiment, the molar proportion of ethoxylated units EO in the polyalkoxylated chain may be less than or equal to 85%, in particular less than or equal to 80%.

According to another particular embodiment, the molar proportion of ethoxylated units EO in the polyalkoxylated chain may be greater than or equal to 80%, in particular greater than or equal to 85%. It can be for example about 88%.

The molar ratio between the ethoxylated units and the propoxylated units of the polyalkoxylated chain may more particularly be between 2.5 and 8, in particular between 2.8 and 7.5, especially between 6 and 7.5. As indicated previously, the total number of ethoxylated and propoxylated units of the polyalkoxylated chain (that is, the sum of m and n) of the monomer (b) is greater than or equal to 10. According to a particular embodiment, it can be between 10 and 150, in particular between 18 and 110 and more particularly between 20 and 70. The polyalkoxylated chain of the monomer (b) according to the invention can thus have a number-average molar mass of between 450 g / mol and 7500 g / mol. g / mol, in particular between 900 g / mol and 5500 g / mol and more particularly between 1000 g / mol and 3500 g / mol. It is understood that the various variants and particular embodiments given above may be combined, as far as possible, to define other particular variants or embodiments. The monomers (b) can be prepared by techniques known to those skilled in the art, by growing the desired polyalkoxylated chain by polymerization from ethylene oxide and propylene oxide monomers to an allyl or methallyl alcohol .

According to one particular embodiment, the monomer or monomers (b) may represent from 1% to 50% by mole, in particular from 5% to 40% by mole, in particular from 5% to 30% by mole and more particularly from 10% to 20% by mole. mol% of the total number of moles of constituent monomers of the copolymer used according to the invention. The monomer (s) (b) may be in various forms, especially in solid form, in particular in the form of powder or flakes, or in liquid form (liquid formed monomers (b) or aqueous monomer solution (b)). In particular, the monomers (b) are water-soluble. Preferably, said monomer (s) (b) are used in liquid form, in particular in aqueous solution, this form being particularly suitable for the synthesis of the copolymer used according to the invention. The molar ratio between the anionic monomer (s) (s) (a) and the monomer (s) (b) used in the composition of the copolymer according to the invention may be more particularly between 1 and 99, in particularly between 2.3 and 19 and more particularly between 4 and 9.

Optional Monomers As indicated above, the copolymer used according to the invention can be obtained by polymerization from a monomer mixture comprising, besides said monomer (s) (a) and said monomer (s). ) (b), one or more additional monomer (s), different from the monomers (a) and (b) noted (s) "monomer (s) (c)" in the following text. The additional monomers (c) may be more particularly chosen from: 2-acrylamino-2-methylpropanesulphonic acid (AMPS), vinylsulphonates, in particular sodium styrene sulphonate, amines, esters having a hydroxyl group, for example hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl methacrylate and hydroxypropyl acrylate, phosphates of alkylene glycol acrylate or methacrylate, in particular methacrylate phosphate, ethylene glycol or else ethylene glycol acrylate phosphate, acrylamide or methacrylamide, phosphonic monomers, such as vinylphosphonates and alkyl phosphonates, macromonomers of formula (VI) below: Ra - REO) q- (PO) r - (B 0) s] - Ra '(VI) wherein: REO) q - (PO) r - (B0),] represents a polyalkoxylated chain consisting of alkoxylated units, divided into blocks, alternate or statistics, chosen Among the ethoxylated units EO, the propoxylated units PO and the butoxylated units BO, q, r and s represent, independently of one another, 0 or an integer ranging between 1 and 250, the sum of m, n and p. being between 10 and 250, Ra represents a radical selected from the group consisting of acrylic esters, methacrylic esters and a mixture of these esters and Ra 'represents hydrogen or an alkyl group having from 1 to 4 carbon atoms the hydrophobic monomers of formula (VII) below: Rb - REO) t - (PO), - (B0)] - Rb '(VII) in which: - REO) t - (P0), - (B0) ),] represents a polyalkoxylated chain consisting of alkoxylated units, divided into blocks, alternating or random, chosen from ethoxylated units EO, propoxylated units PO and butoxylated units BO, t, u and v represent, independently of each other , 0 or an integer 5 varying between 1 and 250, the sum of m, n and p being between 10 and 250, Rb represents a radical selected from the group consisting of acrylic esters, methacrylic esters and a mixture of these esters and Rb 'represents an alkyl group having from 8 to 40 carbon atoms and - the crosslinking monomers .

According to a particular embodiment, in the aforementioned formula (VI), s is equal to 0 and q and r represent an integer ranging between 1 and 250, for example between 10 and 150 or between 10 and 100. According to one embodiment, in particular, in formula (VII) above, v is equal to 0 and t and u represent an integer ranging between 1 and 250, for example between 10 and 150 or between 10 and 100. The monomer or monomers (s) ) additional (s) (c) may be further selected from the crosslinking monomers. The copolymer according to the invention may, for example, comprise a single crosslinking monomer. According to another embodiment, it comprises two different crosslinking monomers. The crosslinking monomer may have a hydrophilic, hydrophobic or amphiphilic character. Examples of these compounds include di (meth) acrylate compounds such as polyalkylene glycol di (meth) acrylate, especially polypropylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, di (meth) polyethylene glycol acrylate, triethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-butylene glycol di (meth) acrylate, di (meth) 1,6-hexanediol acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, but also 2,2'-bis (4- (acryloxypropyloxyphenyl) propane, 2,2'-bis (4- (acryloxydiethoxyphenyl) propane and zinc acrylate, tri (meth) acrylate compounds such as trimethylolpropane tri (meth) acrylate, tri (meth) acrylate trimethylolethane, pentaerythritol tri (meth) acrylate and tetramethylolmethane tri (meth) acrylate, tetra (meth) acrylate compounds such as ditrimethylolpropane tetra (meth) acrylate, tetra ( tetramethylolmethane meth) acrylate and pentaerythritol tetra (meth) acrylate, hexa (meth) acrylate compounds such as dipentaerythritol hexa (meth) acrylate, penta (meth) acrylate compounds such as penta (meth) dipentaerythritol acrylate, allyls such as Fall) / (meth) acrylate, diallylphthalate, diallyl itaconate, diallyl fumarate and diallyl maleate, polyallyl sucrose ethers having from 2 to 8 groups per molecule, Polyallyl ethers of pentaerythritol such as pentaerythritol diallyl ether, pentaerythritol triallyl ether and pentaerythritol tetraallyl ether, polyallyl ethers of trimethylolpropane such as diallyl trimethylolpropane ether and triallyl trimethylolpropane ether. Other polyunsaturated compounds include divinyl glycol, divinyl benzene, divinylcyclohexyl and methylenebisacrylamide.

In another aspect, the crosslinking monomers may be prepared by an esterification reaction of a polyol with an unsaturated anhydride such as maleic anhydride, itaconic anhydride or (meth) acrylic anhydride or by a reaction of addition with an isocyanate such as 3-isopropenyl-dimethylbenzene isocyanate. The following compounds can also be used to obtain crosslinking monomers: polyhaloalkanols such as 1,3-dichloroisopropanol and 1,3-dibromoisopropanol, haloepoxyalkanes such as epichlorohydrin, epibromohydrin, 2-methyl epichlorohydrin and epiiodohydrin, polyglycidyl ethers such as 1,4-butanediol diglycidyl ether, glycerin-1,3-diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, bisphenol A-epichlorohydrin epoxy resin and mixtures. According to a particular embodiment, the crosslinking monomer is chosen from (meth) acrylates having at least two polymerizable ethylenically unsaturated double bonds (for example prepared by esterification of (meth) acrylic acid with a linear or branched polyol having 2 to 12 carbon atoms and at least two hydroxyl groups), polyalkenyl polyethers having at least two polymerizable ethylenically unsaturated double bonds (for example prepared by etherification of alkenyl halide with a linear or branched polyol having from 2 to 12 carbon atoms and at least two hydroxyl groups) and mixtures of these cross-linking monomers. According to one embodiment of the present invention, the copolymer comprises two crosslinking monomers: said first crosslinking monomer being a (meth) acrylate having at least two polymerizable ethylenically unsaturated double bonds (for example prepared by esterification of acid ( meth) acrylic with a linear or branched polyol having 2 to 12 carbon atoms and at least two hydroxyl groups) and - said second crosslinking monomer being a polyalkenyl polyether having at least two polymerizable ethylenically unsaturated double bonds (eg prepared by etherification of alkenyl halide with a linear or branched polyol having 2 to 12 carbon atoms and at least two hydroxyl groups). According to another embodiment, the copolymer comprises two crosslinking monomers of different natures, for example trimethylolpropane tri (meth) acrylate (TMPTA 10 or TMPTMA) and trimethylolpropane diallyl ether (TMPDAE). It is understood that the content of additional monomer (s) used, for example monomer (s) crosslinking (s), is adjusted not to alter the desired properties of the copolymer. In a general manner, the additional monomer (s) (s) (c) may represent less than 20 mol%, in particular less than 15 mol%, especially less than 10 mol% and more particularly less than 5% mol%. molar of the total number of moles of constituent monomers of the copolymer according to the invention. The various particular modes described for each of the monomers used in the composition of the copolymer used according to the invention can be combined.

According to a particular embodiment, the copolymer used according to the invention can thus be obtained by polymerization from a monomer mixture comprising or even consisting of: one or more anionic monomer (s) (a) chosen from acrylic acid, methacrylic acid and mixtures thereof, in particular acrylic acid and one or more monomers (b) of formula (I ') above, in particular of formula ( II), in which the ethoxylated and propoxylated units are more particularly divided into blocks. According to a particular embodiment, the copolymer according to the invention comprises at least units derived from acrylic acid and units deriving from a monomer of formula (II), in particular of formula (III) as described above. . According to a first particular embodiment, the copolymer used according to the invention is obtained by polymerization of at least: - 50% to 99% molar of at least one anionic monomer (a), in particular as defined above and 30 - 1% to 50% molar of at least one monomer (b) of formula (I), in particular as defined above, the molar percentages of each monomer being expressed relative to the total number of moles of constituent monomers of the copolymer.

According to a second particular embodiment, the copolymer used according to the invention is obtained by polymerization of at least: 70% to 95% molar of at least one anionic monomer (a), in particular as defined previously and 5% to 30 mol% of at least one monomer (b) of formula (I), in particular 10 as defined above, the molar percentages of each monomer being expressed relative to the total number of moles of constituent monomers of the copolymer. According to a third particular embodiment, the copolymer used according to the invention is obtained by polymerization of at least: 15 - 80% to 90 mol% of at least one anionic monomer (a), in particular as defined previously and - 10% to 20% molar of at least one monomer (b) of formula (I), in particular as defined above, the molar percentages of each monomer being expressed relative to the total number of moles of constituent monomers of the copolymer. According to these three particular embodiments, the sum of the molar percentages of the monomers (a) and of the monomers (b) is equal to 100%. In other words, according to these three embodiments of the invention, the copolymer consists solely of units derived from the monomers (a) and (b) in the molar proportions indicated.

The copolymer according to the invention may have a weight average molecular weight M w of between 15 000 g / mol and 250 000 g / mol, in particular between 20 000 g / mol and 200 000 g / mol and more particularly between 25 000 g / mol and 175,000 g / mol. The weight average molecular weight or Mw can be determined by Steric Exclusion Chromatography (CES), as more specifically described in the following example. The copolymer used according to the invention may be in the form of salts, stoichiometric or otherwise, mixed or not, and consisting of alkali metals, alkaline earth metals, amines or quaternary ammoniums.

According to one particular embodiment, the copolymer according to the invention is in acid form. According to another embodiment, the copolymer according to the invention is in neutralized form.

According to yet another embodiment, the copolymer according to the invention is in partially or totally neutralized form. According to a particular embodiment, the copolymer is neutralized with an ion selected from the group consisting of potassium ion, sodium ion, lithium ion, calcium ion, magnesium ion, ammonium ion, the diethanolammonium ion and a mixture of these ions.

The copolymer according to the invention can be prepared by conventional polymerization techniques from monomers (a), (b) and optionally (c). According to an alternative embodiment, the copolymer according to the invention can be obtained by radical polymerization, in particular by controlled radical polymerization. According to another of its aspects, the invention relates to a copolymer as defined above, in particular obtained by polymerization from a monomer mixture comprising: at least one anionic monomer (a) as described above and at least one monomer (b) of formula (I) as described above, for which the polyalkoxylated chain has a molar proportion in ethoxylated units of greater than or equal to 70% and strictly less than 90%. UTILIZATION FOR INCREASING RESISTANCE TO YOUNG AGES HYDRAULIC COMPOSITIONS As mentioned above, the copolymers according to the invention are particularly effective in increasing the mechanical strength at young ages of hydraulic compositions. The invention thus relates to a method for increasing the mechanical strength at young ages, and particularly at 1 day, of a hydraulic composition comprising adding to said hydraulic composition at least one copolymer as described above.

The adjuvanted hydraulic composition according to the invention has a faster development of the mechanical strength at young ages, especially at 1 day. Advantageously, the resistance at 1 day (measured according to the EN 12390-3 standard) of the hydraulic composition added according to the invention may be greater than or equal to 155% of the value of the strength of the hydraulic composition devoid of carbon dioxide. copolymer according to the invention. In particular, it may be greater than or equal to 160%, in particular greater than or equal to 170% and more particularly greater than or equal to 180%, of the value of the strength of the hydraulic composition devoid of copolymer according to the invention.

The invention thus relates to the use of at least one copolymer as described above as an adjuvant in a hydraulic composition, for example a concrete composition, for increasing the rate of development of the mechanical resistance at young ages. especially at 1 day. The adjuvant according to the invention can be used in various forms, in particular in liquid form. It may in particular be in the form of an aqueous solution of one or more copolymers according to the invention, the dry extract of which may more particularly be between 25% and 65%, for example between 30% and 60%. According to another of its aspects, the invention relates to the use of a copolymer as defined above as a water-reducing agent in a hydraulic composition.

It also relates to a water-reducing agent for hydraulic compositions comprising, or even consisting of, one or more copolymer (s) as defined above. The water-reducing agent according to the invention, in addition to allowing a reduction in the amount of water of the hydraulic composition in which it is used, advantageously allows a faster development of the mechanical resistance at young ages. , especially at 1 day. According to yet another of its aspects, the invention relates to a hydraulic composition comprising at least one copolymer as described above. The hydraulic compositions can be of various kinds. They may be for the manufacture of a grout, a plaster, a glue, a concrete or a mortar. They may include impurities, for example clays. These compositions may in particular comprise latices, fibers, organic granulates, inorganic granulates, fillers or fillers and / or CaCO3. Hydraulic compositions, for example concrete and mortar compositions, may comprise as hydraulic binder various types of cements, such as, for example, CEM I, CEM II, CEM III, CEM IV and CEM V cements as described. in the standard EN 197-1. Of these, CEM I cements do not have additions. It is possible, however, to add to these cements slags, fly ash, fillers or fillers of limestone, fillers or siliceous fillers. The concrete compositions may be concrete of classes of different strengths, such as C20 / 25 to C100 / 115. The hydraulic composition may more particularly be an aqueous formulation comprising, in addition to said copolymer (s) according to the invention, water and at least one hydraulic binder. It may furthermore include one or more additive (s) annex (s). The hydraulic binder may comprise at least one cement, for example a Portland cement. Mention may also be made, by way of examples, of hydraulic binders of aluminous cement type and sulpho-alumino-calcium cement.

The hydraulic composition according to the invention may, for example, comprise from 8% to 75%, for example from 10% to 50% or from 10% to 40% by weight of hydraulic binder with respect to the total weight of the hydraulic composition. . The at least one copolymer (s) according to the invention may be added to the other constituents of the hydraulic composition during its manufacture.

The at least one copolymer (s) may be used according to the invention in a proportion of from 0.05% to 3% by weight, in particular from 0.25% to 2.5% by weight relative to the total weight of the hydraulic composition. According to a particular embodiment, the hydraulic composition according to the invention thus comprises, with respect to the total weight of the composition: from 2% to 15% by weight of water, from 10% to 30% by weight of hydraulic binder comprising a cement and - from 0.05% to 3% by weight of one or more copolymer (s) according to the invention. According to this embodiment, the hydraulic composition according to the invention can also comprise, in addition, from 10% to 60% by weight of sand.

According to one particular embodiment, the hydraulic composition according to the invention may comprise, relative to the total weight of the composition: from 2% to 15% by weight of water, from 10% to 30% by weight of hydraulic binder comprising a cement, from 0.05% to 3% by weight of one or more copolymer (s) according to the invention, from 10% to 60% by weight of sand and from 10% to 60% by weight. % by weight of one or more gravel (s). Of course, the invention is in no way limited to these particular embodiments.

A hydraulic composition according to the invention may comprise various ingredients, conventionally used in the field of hydraulic compositions, in particular chosen from sand, gravel, aggregates, fillers or fine or ultra-fine fillers, for example calcium carbonate or silica, defoamers, thickeners, stabilizers, biocides or antibacterials, and accelerators or setters. The present invention also relates to the use of one or more copolymer (s) as described above for the preparation of a hydraulic composition advantageously having a mechanical strength at young ages, especially at 1 day, high. The invention will now be described by means of the following example, given by way of illustration and not limitation of the invention.

EXAMPLE 1. Preparation of hydraulic compositions 1.1. Preparation of the Copolymers Measurement of the Molecular Weight of the Copolymers The molecular weight of the copolymers is determined by Steric Exclusion Chromatography (CES). Such a technique employs a WATERSTm brand liquid chromatography apparatus with two detectors. One of these detectors combines the static dynamic scattering of light at a 90 ° angle with the viscometry measured by a VISCOTEK ™ MALVERN ™ viscometer. The other of these detectors is a WATERS refractometric concentration detector. This liquid chromatography apparatus is provided with steric exclusion columns 30 suitably selected by those skilled in the art in order to separate the different molecular weights of the polymers studied. The liquid phase of elution is an aqueous phase containing 1% of KNO3. In a detailed manner, in a first step, the polymerization solution in the eluent of the CES, which is a 1% solution of KNO3, is diluted to 0.9% dry. Then, it is filtered at 0.2 .mu.m. 100 μl are then injected into the chromatography apparatus (eluent: a 1% solution of KNO3). The liquid chromatography apparatus contains an isocratic pump (WATERS TM 515) with a flow rate of 0.8 ml / min. The chromatography apparatus also comprises a furnace which itself comprises in series the following system of columns: a precolumn of GUARD COLUMN ULTRAHYDROGEL WATERS Tm type 6 cm long and 40 mm inside diameter, a linear column of ULTRAHYDROGEL type WATERSTm 30 cm long and 7.8 mm inner diameter and two columns ULTRAHYDROGEL 120 ANGSTROM WATERSTm 30 cm long and 7.8 mm 10 inside diameter. The detection system, on the other hand, consists of a RI WATERSTm 410 type refractometric detector and the other side of a dual viscometer detector and light scattering at a 90 ° angle 270 DUAL DETECTOR MALVERNTm. The oven is heated to 55 ° C and the refractometer is heated to 45 ° C. The chromatography apparatus is calibrated with a single PEO 19k standard of the Po1yCALTM MALVERNTm type. Copolymer A (not according to the invention) Copolymer A is obtained by polymerization from a monomer mixture of: - 85.9 mol% of acrylic acid and - 14.1 mol% of methallyl polyethylene glycol (Mw = 2400 g / mol).

Copolymer Synthesis Protocol A The chemicals used are: -0.11 g iron sulfate (Fe504.7H20), 2.0 g DMDO (1,8-dimercapto-3,6-dioxaoctane, No. CAS: 14970-87-7), - 297 g of 60% methallyl polyethylene glycol (Mw = 2400 g / mol), 30 - 32.5 g of acrylic acid, - 5.6 g of hydrogen peroxide at 35% and - 5.6 g of 40% sodium bisulfite. In the reactor containing 50 g of water, iron sulfate, 20% of the DMDO and 90% of the 60% methallyl polyethylene glycol are introduced. The reactor is heated to 55-60 ° C. Acrylic acid is injected in parallel into the reactor, a solution containing the remainder of 60% DMDO and 60% methallyl polyethylene glycol, hydrogen peroxide and a solution of sodium bisulfite for 1 hour 40 minutes. The injection pipes are rinsed with 120 g of water and the reactor is maintained in temperature at 58-62 ° C for 1:30.

The product is cooled and then neutralized by the addition of 34.1 g of 50% NaOH. The copolymer A obtained has a molecular mass, measured as described above, of 128,200 g / mol. Copolymer B (in accordance with the invention) Copolymer B is obtained by polymerization from a monomer mixture of: - 83.4 mol% of acrylic acid and - 16.6 mol% of monomers (b ) of formula (I ') in which R 1 represents CH 3 and having a polyalkoxylated chain of average molar mass of 1990 15 g / mol, formed at 75 mol% of ethoxylated units and 25 mol% of propoxylated units, the ethoxylated units and propoxylated being divided into blocks. Synthesis Protocol for Copolymer B The chemicals used are: -0.11 g of iron sulphate (FeSO4.7H2O), 2.3 g of DMDO, 297.3 g of monomers (b), -32, 5 g of acrylic acid, 5.6 g of 35% hydrogen peroxide and 25 - 5.6 g of 40% sodium bisulfite. In the reactor containing 50 g of water, iron sulfate, 15% of the DMDO and 89% of the methallyl polyethylene glycol at 60% are introduced. The reactor is heated to 55-60 ° C. Acrylic acid is injected in parallel into the reactor, a solution containing the remainder of DMDO and 60% methanol / polyethylene glycol, hydrogen peroxide and a solution of sodium bisulfite for 1 hour 40 minutes. The injection pipes are rinsed with 120 g of water and the reactor is maintained in temperature at 58-62 ° C for 1:30. The product is cooled and then neutralized by adding 35.8 g of 50% NaOH. The copolymer B obtained has a molecular mass, measured as described above, of 86 100 g / mol. Copolymer C (in accordance with the invention) Copolymer C is obtained by polymerization from a mixture of: - 87.2 mol% of acrylic acid and - 12.8 mol% of monomers (b) of formula (I ') wherein R 1 is CH 3 and having a polyalkoxylated chain of average molar mass of 2700 g / mol, formed at 88 mol% of ethoxylated units and 12 mol% of propoxylated units, the ethoxylated and propoxylated units being divided into blocks. Synthesis Protocol for Copolymer C Copolymer C is prepared according to a procedure similar to that described above for copolymer B. The copolymer C obtained has a molecular mass, measured as described above, of 147,200 g / mol. 1.2. Preparation of hydraulic compositions In each of the tests, a concrete (660 kg / m3) was prepared according to EN 480-1 standard by shaking with standardized sand (0/4), cement (CEM I 52.5N Holcim), 4/11 gravel, water and an antifoam agent. No adjuvant is added to composition 1 (control).

Formulations 2 to 4 of concrete are supplemented respectively by the solutions of copolymers A, B and C prepared as previously described. For the preparation of the concrete formulations 2 to 4 respectively incorporating the copolymers A, B and C, the amount of added water is imposed so that the three adjuvanted hydraulic compositions have the same reduction in water (30%) by compared to the control concrete. The proportions of each of the constituents of the hydraulic compositions thus prepared are shown in Table 1 below. 2. Evaluation of Hydraulic Compositions The compositions are evaluated for their properties of initial fluidity (TO handleability), air capture, water reduction and compressive strength at 1 day, according to the following protocols.

3033787 23 Measurement of the maneuverability to TO The measurement of the initial fluidity (or maneuverability at TO) is carried out, at ambient temperature, by means of a frustoconical bottomless cone of galvanized steel, called Abrams cone, according to the EN 12350-2 standard. This cone has the following characteristics: Upper diameter: 100 ± 2 mm Lower diameter: 200 ± 2 mm Height: 300 ± 2 mm. The cone is placed on a plate moistened with a sponge.

The cone is then filled with a determined amount of each of the preparations. The filling lasts 2 minutes. The contents of the cone are packed with a metal rod. As soon as the filling is completed, the cone is lifted vertically, which leads to the collapse of its contents on the plate. The diameter of the slab thus formed is measured after 30 seconds.

Concretes can be classified according to their workability according to EN 206-1. In particular, it may be considered that concretes having a spread of less than or equal to 60 mm have equivalent consistencies. Measurement of the air capture The measurement of the air capture is in accordance with the EN 12350-7 standard, paragraph 3.3. Measurement of water reduction It is measured according to the standard ADJUVANT NF EN 934-2.

Measurement of the compressive strength The measurements of compressive strength at 1 day are made according to the standard EN 12390-3, paragraph 3. The compressive strength is expressed in MPa. The tests were performed on a Class 1 test machine according to EN 12390-4.

The results obtained for the different hydraulic compositions are shown in the following Table 1.

3033787 24 Test Composition 1 Composition 2 Composition 3 Composition 4 (negative control) (non-compliant) (compliant) (compliant) Sand (kg) 24.4 24.4 24.4 24.4 Gravel 4/11 (kg) 35, 6 35.6 35.6 35.6 Cement (kg) 25 25 25 Water (g) 12411 8687 8687 8687 Weight ratio 0.50 0.34 0.34 0.34 water / cement Water reduction 0% 30% 30% 30% Adjuvant (g) Copolymer A Copolymer B Copolymer C (189) (187) (189) Material content 39.7% 40.1% 39.7% dry adjuvant% dry adjuvant / cement 0.3 0.3 0.3 Antifoaming agent 0.5 0.5 0.5 (% / adjuvant) Handling TO (mm) 580 580 520 560 TO air capture 1.0% 3.2% 2.9% 2.9% Sample Weight 4.82 4.92 4.92 4.96 Resistance to the 16.0 24.4 25.5 30.3 compression at 1 day (MPa)% of the value of 100% - 153% - 159% - 189% resistance of the control TABLE 1 All the hydraulic compositions have a homogeneous appearance, without segregation of the constituents. The use of the copolymers B and C according to the invention makes it possible to obtain high compressive strengths at 1 day, while maintaining an initial consistency (maneuverability TO) satisfactory. In particular, it is demonstrated that the copolymers B and C according to the invention make it possible, for the same water reduction of the hydraulic composition, to obtain improved strengths (about 5% and 24% respectively). ), compared to the implementation of the copolymer A not according to the invention, while maintaining a good maneuverability of the hydraulic composition.

Claims (11)

REVENDICATIONS1. Use for increasing the mechanical strength at young ages of a hydraulic composition of at least one copolymer obtained by polymerization from a monomer mixture comprising: at least one anionic monomer (a) comprising a polymerizable unsaturated functional group and a grouping and at least one monomer (b) of the following formula (I): ## STR2 ## which: R 1 represents a hydrogen atom or a group CH 3, p is 1 or 2, [(E 0). - (P0) ,,, [represents a polyalkoxylated chain consisting of ethoxylated units EO and propoxylated units PO, divided into blocks, alternating or statistical and m and n represent integers varying between 1 and 250, the sum of m and n being greater than or equal to 10, provided that the molar proportion of the ethoxylated units in the polyalkoxylated (n) / (m + n) chain is strictly less than 90%. 2. Use according to claim 1, to obtain a resistance of the hydraulic compression composition to 1 day, measured according to the EN 12390-3 standard, greater than or equal to 155%, in particular greater than or equal to 160%, especially greater or equal to 170% and more particularly greater than or equal to 180% of the value of the strength of the hydraulic composition free of said copolymer (s). 3. Use according to any one of the preceding claims, wherein said copolymer (s) is used in a proportion of from 0.05% to 3% by weight, in particular from 0.25% to 2.5% by weight. relative to the total weight of the hydraulic composition. 4. Use according to any one of the preceding claims, characterized in that the monomer (s) (s) (b) have the following formula (I '): H2C = C (-R1) -CH2 -O-RE0). Wherein R 1, n and m are as defined in claim 1. 5. Use according to any one of the preceding claims, characterized in that said copolymer is obtained from at least one monomer (b) of formula (II) below: H2C = C (-CH3) - CH2 - O - Wherein m and n are as defined in claim 1. 6. Use according to any one of the preceding claims, characterized in that said copolymer is obtained from at least one monomer (b) of the following formula (III): ## STR3 ## where n is such that defined in claim 1. 7. Use according to any one of the preceding claims, characterized in that the molar proportion of ethoxylated units EO in the polyalkoxylated chain of said monomer (s) (b) is greater than or equal to 70%, in particular between 70% and 88%, preferably greater than or equal to 75%. 8. Use according to any one of the preceding claims, characterized in that the total number of ethoxylated and propoxylated units (m + n) of the polyalkoxylated chain of the monomer (b) is between 10 and 150, in particular between 18 and 110 and more particularly between 20 and 70. 9. Use according to any one of the preceding claims, characterized in that the said monomer (s) (b) represent from 1% to 50% by mole, in particular from 5% to 40% by mole, in particular by 5%. at 30 mol% and more particularly from 10% to 20 mol% of the total number of moles of constituent monomers of said copolymer. 10. Use according to any one of the preceding claims, characterized in that the said anionic monomer (s) (a) are selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and mixtures of these monomers, in particular are selected from acrylic acid, methacrylic acid and mixtures thereof. 5 11. Use according to any one of the preceding claims, characterized in that said copolymer is obtained by polymerization from a monomer mixture comprising, besides the said anionic monomer (s) (a) and the or said monomer (s) (b) of formula (I), one or more monomers (s) (c) chosen from: - 2-acrylamino-2-methylpropanesulphonic acid (AMPS), 10 - vinylsulphonates , in particular sodium styrene sulphonate, - amines, - esters having a hydroxyl group, for example hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl methacrylate and hydroxypropyl acrylate, - phosphates alkylene glycol acrylate or methacrylate, in particular ethylene glycol methacrylate phosphate or ethylene glycol acrylate phosphate, acrylamide or methacrylamide, phosphonic monomers such as vinylphosphonates and 20 alkyl phosphonates the macromonomers of the following formula (VI): Ra - REO) q - (PO) r - (B0), - Ra '(VI) in which: REO) q - (PO) r - (B0), ] represents a polyalkoxylated chain consisting of alternately or randomly distributed alkoxylated units selected from the ethoxylated units EO, the propoxylated units PO and the butoxylated units BO, q, r and s represent, independently of one another, Or an integer ranging from 1 to 250, the sum of m, n and p being from 10 to 250, Ra represents a radical selected from the group consisting of acrylic esters, methacrylic esters and a mixture of these esters. and Ra 'represents hydrogen or an alkyl group having from 1 to 4 carbon atoms, - the hydrophobic monomers of formula (VII) below: Rb - REO) t- (P0)' - (B0) 1 - Rb '( VII) in which: REO) t - (P0), - (B0),] represents a polyalkoxylated chain consisting of alkoxylated units, divided into blocks, alte of the ethoxylated units EO, the propoxylated units PO and the butoxylated units BO, 5 t, u and v represent, independently of one another, 0 or an integer ranging between 1 and 250, the sum of m , n and p being from 10 to 250, Rb represents a radical selected from the group consisting of acrylic esters, methacrylic esters and a mixture of these esters and Rb 'represents an alkyl group having from 8 to 40 carbon atoms and The crosslinking monomers.