EP3230345A1

EP3230345A1 - Continuous esterification and/or amidification method, without organic solvent, of an acid copolymer or homopolymer

Info

Publication number: EP3230345A1
Application number: EP15817484.7A
Authority: EP
Inventors: Jean-Marc Suau; David Platel; Clémentine CHAMPAGNE; Yves MATTER
Original assignee: Coatex SAS
Current assignee: Coatex SAS
Priority date: 2014-12-08
Filing date: 2015-12-07
Publication date: 2017-10-18
Also published as: CA2963864A1; WO2016092190A1; US20170297255A1; CN106795367A; CN106795367B; US10207446B2; FR3029524B1; FR3029524A1; JP2018500397A; MY191556A; KR20170092531A; MX2017007439A

Abstract

The invention relates to a continuous method for producing a comb polymer, without organic solvent, by esterification and/or amidification of an acid copolymer or homopolymer, consisting in esterifying and/or amidifying said copolymer/homopolymer by hot reaction in the zone for mixture and transport of a tube reactor, optionally provided with a water elimination system, in the presence of at least one poly(alkylene glycol) in a solid form or in a melted form and an antioxidant, said esterification and/or amidification being carried out at a temperature higher than or equal to 170°C.

Description

CONTINUOUS METHOD OF ESTERIFYING AND / OR ORGANIC SOLVENT-FREE AMIDIFICATION WITH AN ACIDIC HOMOPOLYMER OR COPOLYMER

Field of the invention

The present invention relates to the technical field of continuous esterification and / or amidation processes for polymers, making it possible to provide acidic acrylic polymers comprising at least one poly (alkylene glycol) side chain.

Background of the invention

Acidic acrylic copolymers having at least one poly (alkylene glycol) side chain are sometimes referred to as comb structure polymers. These are copolymers having a skeleton essentially of carboxylic nature on which are grafted side chains (also called "hanging chains") of poly (alkylene glycol) type.

There are now two main routes for the preparation of these comb structure copolymers.

The first synthetic route of these copolymers is copolymerization in the presence of acidic acrylic monomers and polymerizable macromonomers comprising poly (alkylene glycol) chains.

The second route of preparation of the comb structure copolymers is the esterification and / or amidation of acrylic acid polymers with polyalkylene glycols. According to this method, an acidic acrylic polymer is prepared by conventional polymerization techniques, for example radical polymerization, and then the esterification and / or amidification of this acidic acrylic polymer is carried out in the presence of poly (alkylene glycol) compounds. The esterification and amidation processes described in the prior art (for example WO 2007/132322, WO 2009/090471, WO 2013/021029, US 2008/0119602) are of discontinuous type with significant reaction times.

The document US 2013/0274368 describes a process for the esterification of a poly (carboxylic acid) polymer by means of polyether compounds, said process being of continuous type in an organic solvent and by exposing the reactants to microwaves in order to initiate and to speed up the reaction.

The method of the present invention is based on the use of a continuous reactor called tubular reactor, for example an extruder. In a tubular reactor, the material can be subjected for a very short time to high temperatures (for example from 100 to 300 ° C.), with the possibility also of applying high local pressures (50 to 150 bars). The tubular reactor may also be equipped with devices ensuring homogeneity of the melt during its flow. Extruders are generally used in continuous processes of transformation, for example shaped, thermoplastic polymers or thermosetting polymers. During these extrusion and injection processes, the polymers are completely melted to give them the shape and appearance desired to obtain the part to be manufactured. Driven by the screws, the material is subjected for a very short time to high temperatures (for example from 100 to 300 ° C), to high local pressures (50 to 150 bar), and to a very intense shear. Extrusion is particularly suitable for resistant materials having a high melting point.

Tubular reactors, such as extruders, can also be used to chemically modify the molten material. The use of an extruder to perform a chemical reaction is called reactive extrusion (REX). Extrusion offers, because of its intrinsic characteristics (temperature, pressure, shear), a solution adapted to react two polymeric materials, inert or otherwise difficult to react.

Reactive extrusion is, moreover, described in the context of the aqueous radical polymerization. Reference may in particular be made to WO 99/58576 which describes the solution polymerization to obtain an acrylic / acrylamide copolymer in the form of a highly crosslinked gel having the consistency of rubber, enclosing at the heart of its three-dimensional network approximately 50 to 70% by weight of water.

Thus, the use of reactive extrusion is described to prepare polymers from raw materials that are not very susceptible to thermodegradation.

Polymers of the poly (alkylene glycol) type, for example poly (ethylene glycol) or PEG, are sensitive to temperature. The degradation of these polymers, under the effect of temperature, by oxidative decomposition, leads to by-products of water type, CO ₂ , aldehyde, simple alcohols, acids, glycol esters and vinyl by-products.

It is the same for comb-type polymers consisting of pendant chains of poly (alkylene glycol) type. The high temperatures can lead to side reactions, for example release of the pendant chains of the comb polymer and unexpected crosslinking, and thus degrade the quality of the polymer obtained. Substantial crosslinking can also lead to gelation of the assembly, to polymers finally insoluble in water.

Brief description of the invention

An object of the present invention is to provide a process for the preparation of comb-type polymers consisting of poly (alkylene glycol) pendant chains by esterification and / or amidification of an acidic polymer by means of poly (alkylene glycol) compounds, said process being of continuous type and at high temperatures. The use of such high temperatures makes it possible to reduce the residence time in the reactor. In doing so, the cost of producing such polymers is reduced and the regularity of the products. Moreover, the operating conditions of the process are such that the degree of degradation of the side chains and the degree of crosslinking are very low. This makes it possible to obtain polymers having a high homogeneity, a low polymolecularity index, and therefore polymers of better quality.

Such a continuous process is very advantageous from an industrial point of view. It considerably reduces the reaction time, and thus increases the profitability of production. Moreover, such a process is more flexible because the use of a tubular reactor, such as an extruder makes it possible to adjust the operating conditions during the process, much faster than in batch or semi-batch process. . Since the total volume is distributed over the length of the reactor and possibly in reaction zones having different temperatures, the volume of reagents to be brought to the desired temperature (at least 170 ° C. in the case of the present invention) is much smaller than that of a batch or semi-batch type reactor and therefore requires less time to perform regulation and temperature corrections. The continuous system therefore has a greater reactivity than non-continuous type systems. Such a method thus makes it possible, for example, to fix the esterification and / or amidation yield as a function of the desired degree of grafting on the comb-type polymer, much more easily.

Such a method makes it possible today to obtain an excellent productivity-quality ratio. DETAILED DESCRIPTION OF THE INVENTION Esterification and / or Amylation Process

An object of the present invention is a continuous process for preparing a comb polymer, without organic solvent, by esterification and / or amidification of an acidic homopolymer or copolymer, comprising esterifying and / or amide-forming said homopolymer / copolymer by hot reaction in the mixing and conveying zone of a tubular reactor, such as an extruder, optionally equipped with a water removal system, in the presence of at least one poly (alkylene) glycol) in solid or melt form and an antioxidant, said esterification and / or amidification occurring at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification catalyst and / or amidifïcation, optionally under reduced pressure and / or under a stream of inert gas.

In one embodiment, the mixing zone comprises a homogenization of the mixture. In one embodiment, the esterification and / or amidification of said homopolymer / copolymer is carried out by hot kneading in the mixing and transport zone of the extruder, optionally equipped with an elimination system of the extruder. water, said esterification and / or amidification occurring at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification catalyst and / or amidation, optionally at reduced pressure and / or under a flow of inert gas.

Such a method makes it possible to obtain a polymer of comb structure also called "comb polymer". These are polymers or copolymers having a backbone of carboxylic nature on which are grafted side chains (also called "hanging chains") of poly (alkylene glycol) type. These side chains are sometimes referred to as polyoxyalkyl side groups.

Depending on the degree of grafting of the final polymer, the acidic skeleton, for example, of carboxylic nature, may have a more or less anionic charge. If the degree of esterification and / or amidation is close to 100%, it means that a large part of the acid functions of the acid polymer, for example the carboxylic groups of an acrylic acid polymer, have been subjected to an esterification and / or amidation reaction and the skeleton of the final polymer is very lightly anionically charged. The degree of esterification and / or amidation of the comb polymer obtained can, for example, be determined by the titration of the acid functions (for example, acid number in mgKOH / g). These acidic functions, for example carboxylic groups, may be in the free acid or acid anhydride form or in the partially neutralized form. The molar proportion of free acid and acid anhydride functional groups in the final comb polymer may vary from 0 to 99%, for example from 5 to 60%.

An advantage of the process of the present invention is to allow easy adjustment of the rate of esterification and / or amidation as required. To do this, it is possible to adjust the residence time parameters and / or molar ratio of the constituents at the inlet of the reactor. In the context of the present invention, said comb polymer obtained by the process of the present invention advantageously has an acid number of between 35 and 234 mg KOH / g (mass of potassium hydroxide, expressed in mg, necessary to neutralize the acidity one gram of polymer). According to one embodiment, said comb polymer obtained by the process of the present invention has an acid number of between 46 and 156 mg KOH / g.

The process of the present invention is carried out continuously. Thus, the introduction of constituents into the tabular reactor, for example the extruder, is "continuous", that is to say at constant or variable speed, but without stopping the introduction.

According to one embodiment of the process of the present invention, the introduction of the constituents into the synthesis reactor is "simultaneous", that is to say that the various constituents are introduced concomitantly.

According to another embodiment of the process of the present invention, the introduction of the constituents into the synthesis reactor is "proportional", that is to say that the proportion of each component of the mixture introduced into the reactor synthesis remains constant over the reaction time, vis-à-vis the other constituents of the mixture.

According to one embodiment of the process of the present invention, the constituents are introduced into the tubular reactor in the form of a homogeneous mixture.

According to one embodiment of the process of the present invention, the mixture of constituents is homogenized at the inlet of the reactor.

The process of the present invention is carried out without organic solvent. Indeed, processes using solvents generate volatile organic compounds (VOCs or English VOC). On the one hand, it is necessary to eliminate these solvents at the end of the reaction, which has the effect of complicating the industrial process for preparing the polymer. On the other hand, the effects on health and the environment of these solvents are recognized as very harmful, so that we try to avoid producing them. Finally, even after purification (distillation), there are still traces of solvent in the polymers obtained. "Solvent" means any substance which is inert to reactants and reaction products in the liquid phase at its temperature of use, the function of which is to dilute other substances without modifying them chemically and without to modify himself.

In addition, the removal of these solvents generates additional costs.

The process of the invention is carried out at high temperatures, the esterification and / or amidification of the homopolymer / copolymer taking place at a temperature greater than or equal to 170 ° C.

The inventors have in fact realized that this temperature makes it possible to obtain the best process time ratio (residence time in the tubular reactor, for example in the extruder) - cost of the process - quality of the comb polymer thus obtained (rate grafting). According to one embodiment of the present invention, the esterification and / or amidification of the homopolymer / copolymer takes place at a temperature greater than or equal to 180 ° C, for example greater than or equal to 200 ° C, 210 ° C or 220 ° C.

The product obtained at the outlet of the tabular reactor, for example at the extruder outlet, is likely to be in the form of a resin (high temperature at the outlet of the tabular reactor, for example at the extrusion outlet) or wax (temperature at the outlet of the tabular reactor, for example extruder, lower than the melting temperature of the comb polymer obtained). In this case, the product has a very high solids content, for example greater than 90%, or for example greater than 95% by weight. Such a product can then be transformed, for example milled, to be in the form of a solid powder, flakes, pellets, rushes, granules ...

Alternatively, the product obtained at the outlet of a tabular reactor, for example an extruder, may be solubilized at the end of the reaction, by addition of water, and optionally an alkali. The amount of water added to the product of the esterification and / or amidification reaction is adjusted to obtain a solution having a defined active ingredient content. Thus, the process of the present invention makes it possible to obtain a product having a high solids content, for example greater than 60% of its weight, while retaining its liquid nature, that is to say that it is perfectly easy to handle and in particular pumpable by judiciously choosing the composition of poly (alkylene glycol) side chains. In this regard, reference is made for example to the document WO 2011/104590 Al (Coatex) which shows that for a poly (alkylene glycol) of given molecular weight, it is possible to adjust the manipulability of the solutions obtained as a function of the number of propylene oxide units relative to the total number of alkylene glycol units of the poly (alkylene glycol). Depending on the transport constraints in particular, it is advantageous to be able to alternately propose a product in powder form or in the form of a solution which has been adjusted dry extract. The method of the present invention allows such flexibility. As explained above, the product of the reaction can be solubilized and / or neutralized.

The neutralizing agent is chosen so that the counterion present in the polymer solution after neutralization is, for example, selected from the group consisting of calcium ion, sodium ion, potassium ion lithium ion, magnesium ion, barium ion, zinc ion, aluminum ion, ammonium ion and amine (for example, 2-amino-2-methylpropanol, triethanolamine, etc.).

The neutralization of the polymer obtained can be total or partial. The molar percentage of neutralization of the active acid sites of the polymer with a neutralizing agent may, for example, vary between 10% and 90%, for example between 15% and 85%.

The neutralization of the polymer obtained can also be simple (a single neutralization agent) or multiple (several neutralization agents).

For example, it is possible to envisage the following modes of neutralization, alone or in combination:

a molar percentage of neutralization of the active acid sites of the polymer by a neutralization agent containing the calcium ion of between 15% and 40%, for example between 20% and 35%,

a molar percentage of neutralization of the active acid sites of the polymer with one or more mono-functional neutralization agents containing the sodium ion of between 7% and 70%, for example between 20% and 60%,

a molar percentage of neutralization of the active acid sites of the polymer by a neutralization agent containing magnesium, barium, zinc, aluminum or an amine ion or mixtures thereof and in particular by a neutralization agent containing the magnesium ion of between 0 and % and 30%, for example between 5% and 25%. Tubular reactor

The method of the invention is based on the use of a continuous reactor called tubular reactor. Equally, the term "esterification reactor" or the term "amidation reactor" is also used. In the context of the present invention, the term "tubular reactor" defines an enclosure, for example cylindrical, preferably closed, equipped with at least one inlet orifice at one end of the enclosure and at least one orifice of exit at the opposite end of the enclosure. For example, it can be considered that an empty cylindrical tube is a tubular reactor. It should be noted that the enclosure may be straight but it is not necessarily. The terms "tubular reactor" or "piston reactor" may alternatively be used. In this case, it is incorrectly assumed that the flow in said reactor is of the piston type, that is to say that the distribution of the residence times in the reactor is monomodal with a very low dispersion.

Said reactor may or may not be equipped with devices, for example mechanical, guaranteeing a homogenization of the fluid during its flow. When mechanically driven screws are used, the tubular reactor is an extruder as described below. But the mixing within the tubular reactor can also result from the use of non-moving parts, for example static mixers. This kind of Mixing devices is marketed by multiple companies, among which, JLS, Samwha, Mixel, Horus-Environment or Sulzer Ltd. The SMX, SMV, SMI type mixers of this company are, for example, equipment capable of performing mixing functions.

The tabular reactor may consist of one, several or even many segments connected in series. It will thus be easy to vary the length of said reactor.

The tabular reactor is preferably equipped with one or more devices for the introduction or removal of reagents or products. For example, it will be possible to connect pumps to said tabular reactor.

The tabular reactor may also be equipped with adjustment systems to adjust the temperature within it. For example, a double jacket system could be used to circulate a heat transfer fluid to the reactor wall. It will also be possible to circulate a heat transfer fluid in an exchanger system within the reactor itself. There are static mixers whose shape is such that they also act as mixing devices.

The tabular reactor can also be equipped with adjustment systems to adjust the (de) pressure within it. By judiciously equipping the reactor valves, valves, weirs can work either at atmospheric pressure or under negative pressure or under positive pressure.

For example, a tubular reactor composed of metal tubes interconnected by a system of joints and collars which guarantee a perfect seal of the system can be used.

For a reactor composed of 10 316 stainless steel tubes thus assembled, with a unit length of 2 meters, and thus a total length of the entire 20 meters, with "DN15" type tubes having an outside diameter of 21.3 mm and a thickness of 1.6 mm and with a first tube equipped with a combination of SMX type and SMV (Sulzer brand) static mixers which guarantee a good mixing of the reagents after their introduction, the residence time can be approximately 30 minutes with an overall flow rate of 10 Kg / h.

For a reactor composed of 10 assembled tubes of unit length 1 meter, and therefore of length of the whole 10 meters, with tubes of type "DN35" having an external diameter of 42.4 mm and a thickness of 2 mm and with a first tube equipped with a combination of SMX-type and SMV-type (Sulzer brand) static mixers which guarantee a good mixing of the reagents after their introduction, a second tube equipped with helicoidal mixers, generating a rotational circulation and allowing to guarantee a better homogenization of the reagents and products, the residence time can be about 20 minutes with an overall flow rate of 35 Kg / h. In one embodiment, the tabular reactor is an extruder.

extruder

The process of the invention is based on the use of a tabular reactor such as an extruder.

In the context of the present invention, the term "extruder" defines an enclosure, for example cylindrical, preferably closed, equipped with at least one inlet orifice at one end of the enclosure and at least one orifice of outlet at the opposite end of the enclosure, and which comprises a mixing zone, a transport zone, and optionally one or more screws. It should be noted that the enclosure may be straight but it is not necessarily. The term "kneader" is alternately used when said extruder does not comprise a transport screw.

The extruder may consist of one or more tabular segments connected in series. The extruder allows hot kneading in the mixing zone raw materials introduced into the enclosure, and then transport to the outlet port. The extruder is preferably equipped with at least one water removal system. The extruder can be equipped with several water removal systems arranged at multiple locations on the enclosure. These water evacuation systems make it possible to eliminate the water, which also has the effect of displacing the equilibrium of the reaction and thus facilitating the esterification / amidation reaction of the homopolymer / acidic copolymer, for example (meth) acrylic acid polymer.

Using an extruder comprising at least one water removal system may also be advantageous because, in this case, the product obtained at the end of the esterification and / or amidation reaction has a solids content. high, for example greater than 90% by weight. It is conceivable to preserve such a dry extract and to transform, for example, the product in the form of solid powder, granules, etc. (reduction of the temperature below the melting point of the polymer and then grinding / crushing / spraying). Alternatively, the product obtained is solubilized at the end of the esterification / amidation reaction in order to have a product in liquid form. Solubilization can take place in the extruder which is then equipped with a water inlet for example. The solubilization can also be physically separated from the extruder.

The extruder can also be equipped with adjustment systems allowing for example to adjust the temperature, the pressure and the rates of the various reagents. Furthermore, the extruder may also be equipped with one or more cooling systems.

The starting homopolymer and / or acidic copolymer has acid functions, for example carboxylic functions, which are the seat of reactions esterification / amidification during the process according to the invention. The proportion of acidic functions in the polymer can be evaluated by measuring the acid number of the polymer. As the number of acid functions decreases during the process of the invention, the variation of the acid number of the polymer makes it possible to monitor the degree of progress of the reaction. Concretely, the acid number can be determined by acid-base measurement using, for example, an aqueous solution of KOH or NaOH (mass of KOH or NaOH, expressed in mg, necessary to neutralize the acidity of a gram of polymer).

According to one aspect of the present invention, said extruder comprises at least one screw, for example two screws.

According to another aspect of the present invention, said tubular reactor, in particular said extruder, comprises several reaction zones having different temperatures varying between ambient temperature and 250 ° C., of which at least one reaction zone having a temperature greater than or equal to 170 ° C. ° C.

For example, said tubular reactor, in particular said extruder comprises three reaction zones having incremental temperatures varying between room temperature (e.g. 20-25 ° C) and 250 ° C, including a reaction zone having a temperature above 180 ° C. Such a configuration allows the introduction of the reactants into the tubular reactor, for example extruder, without prior heating thereof.

Examples of extruders adapted to the process of the present invention are given in document FR 2 993 887.

The use of a tubular reactor, in particular an extruder, makes it possible to rapidly bring the reactants to the esterification and / or amidation temperature. The preheating and then cooling times, which are generally important in batch processes, are within the scope of the present invention reduced or even negligible. However, these preheating and cooling times generally correspond to uncertainties as to the quality of the polymer obtained. Reducing the warm-up time further reduces the risks associated with these uncertainties.

According to one embodiment of the process of the present invention, the residence time in said tubular reactor, in particular the extruder, is greater than or equal to 4 minutes, for example between 4 to 40 minutes or between 6 to 30 minutes, as a function of the number of conveying screws present in said tubular reactor, in particular the extruder. Homopolymer / acidic copolymer

According to one aspect of the present invention, said acid homopolymer or copolymer to be esterified and / or amidified results from the polymerization or copolymerization of at least one of the monomers selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid and maleic anhydride.

According to another aspect of the present invention, said acid homopolymer or copolymer to be esterified and / or amidified results from the polymerization or copolymerization of a monomer represented by the formula (1):

in which :

Ri, R ₂ and R ₃ independently of one another, a hydrogen atom, methyl or (CH ₂₎ _Z - ₂ COOM,

(CH ₂ ) _Z - COOM ₂ may form an anhydride together with -COOMi or another (CH ₂ ) _Z - COOM ₂ and in this case, Mi and M ₂ are not present and z = 0, 1 or 2, Mi and M ₂ represent, independently of one another, a hydrogen atom, a metal atom, an ammonium group or an organic amino group.

In yet another aspect, said homopolymer or copolymer to be esterified and / or amidified is of acrylic acid type and results from the polymerization or copolymerization of acrylic acid and / or methacrylic acid.

According to one aspect of the present invention, said homopolymer or copolymer to be esterified and / or amidified is substantially linear. In this case, the sequence of monomer units is linear but may have some random or regular branches.

Said homopolymer or acidic copolymer can be obtained by any radical polymerization process, for example in solution, in direct or inverse emulsion, in suspension or precipitation in appropriate solvents, in the presence of catalytic systems and transfer agents. Mono functional or multifunctional chain transfer agents are used. It can be a controlled radical polymerization process, for example by nitroxides (NMP) or cobaloxymes, or a radical atom transfer polymerization (ATRP) process. We also quote the controlled radical polymerization processes with sulfur derivatives, selected from carbamates, dithioesters, trithiocarbonates (RAFT) and xanthates.

For example, hydrogen peroxide or a persulfate which acts as an initiator may be used, as well as, for example, copper sulfate which acts as a catalyst and a chain transfer agent.

Alternatively, thio lactic acid, or another mercaptan having one or more SH functions, is used as an additional chain transfer agent.

Still other processes use sodium hypophosphite, of the chemical formula NaPO ₂ H ₂ , as a chain transfer agent and oxy-reductant, in the presence of hydrogen peroxide or hydrogen peroxide generator. radicals such as persulfate.

In this regard, reference is made in particular to the following documents which describe various processes for the radical polymerization of acrylic acid: WO 02/070571, WO 2005/095466, WO 2006/024706, WO 2014/049252.

Said homopolymer or acidic copolymer may be in the form of an aqueous solution or in dry form.

Said homopolymer or acidic copolymer can be in completely acidic or partially neutralized form. The molar percentage of neutralization of the active acid sites of said acid homopolymer or copolymer to be esterified and / or to be amidified by a neutralization agent may, for example, be less than or equal to 90%, for example less than or equal to 80%, or less or equal to 70%.

If the polymer to be esterified and / or amidified is partially neutralized, it may be by means of a single neutralizing agent or several neutralizing agents.

a molar percentage of neutralization of the active acid sites of the polymer with one or more monofunctional neutralization agents containing the sodium ion and / or the lithium ion of between 7% and 70%, for example between 20% and 60%,

a molar percentage of neutralization of the active acid sites of the polymer with a neutralization agent containing the magnesium, barium, zinc or aluminum ion or a difunctional amine or their mixtures and in particular with a neutralization agent containing the magnesium ion between 0% and 30%, for example between 5% and 25%. The polymers, in particular the acidic polymers of the present invention, may be characterized by two following indices:

the IP polymolecularity index (also referred to as PD equivalent polydispersity); and

the molecular weight by weight.

The polymolecularity index corresponds to the molecular weight distribution of the different macromolecules within the polymer. If all the macromolecules have the same degree of polymerization (and therefore the same molecular weight), this index is close to 1. If on the other hand, the macro molecules have different lengths (and therefore different molecular weights), the IP index is greater than 1.

According to one aspect of the present invention, said acid homopolymer or copolymer to be esterified and / or amidified has a polydispersity index IP (Mw / Mn ratio) of between 1 and 3, for example between 1.5 and 3 or between 2 and 2.5.

The molecular weight Mw of such polymers may for example be determined by size exclusion chromatography (CES) or in English "Gel Permeation Chromatography" (GPC).

According to one aspect of the present invention, said acid homopolymer or copolymer to be esterified and / or amidified is a polymer of acrylic acid and / or methacrylic acid of molecular weight Mw between 1000 and 20 000 g / mol, as determined by GPC, for example between 1,000 and 15,000 g / mol, between 1,000 and 10,000 g / mol or alternatively between 1,500 and 8,000 g / mol.

According to still another aspect of the present invention, said acid homopolymer or copolymer to be esterified and / or amidified has a molecular weight of less than 8000 g / mol and a polydispersibility index IP of between 2 and 3.

Said homopolymer or acid copolymer to be esterified and / or amidified can be characterized by its acid number. This acid number may in particular correspond to the presence of carboxylic groups.

In the context of the present invention, said comb polymer obtained by the process of the present invention has an acid number advantageously between 35 and 234 mg KOH / g (mass of potassium hydroxide, expressed in mg, necessary to neutralize the acidity one gram of polymer). According to one embodiment, said comb polymer obtained by the process of the present invention has an acid number of between 46 and 156 mg KOH / g.

Poly (alkylene glycol) compounds

In the context of the present invention, one or more poly (alkylene glycol) compounds are used.

By "poly (alkylene glycol)" (abbreviated PAG) or, equivalently, "poly (oxyalkylene)" (abbreviated POA), is meant a compound consisting of a polymer chain consisting of units (or units) of oxides alkylene, for example ethylene oxide, propylene oxide, 1-butylene oxide, such compounds are commercially available and obtained by polymerization of the corresponding epoxides.

In the context of the present invention, the poly (alkylene glycol) compounds are advantageously monofunctional, that is to say that they comprise:

at one of their end, a reactive function of the type -OH or -NHR (in which

R represents H or a hydrocarbon chain containing from 1 to 10 carbon atoms), and

at the other end, a hydrocarbon chain having 1 to 100 carbon atoms, for example 1 to 70, 1 to 50, 1 to 30 or 1 to 10 carbon atoms.

In this case, when said monofunctional poly (alkylene glycol) has an -OH terminus, the terms "alkoxy poly (oxyalkylene glycol)" or "monoalkylether poly (alkylene glycol)" can also be used. Such a mono-functional compound is grafted onto the acidic polymer by esterification.

When said mono-functional poly (alkylene glycol) has an -NHR terminus, it is also possible to use the terms "α-amino-alkoxy-poly (oxyalkylene glycol)" or "α-amino-alkyl ether-poly (alkylene glycol)". Such a monofunctional compound is grafted onto the acidic polymer by amidification.

At least one other poly (alkylene glycol) compound may also be used, and it may also be monofunctional or alternatively it may be difunctional, that is to say it may comprise a reactive function of OH or -NHR (wherein R is H or a hydrocarbon chain having from 1 to 10 carbon atoms) at each of its ends.

More generally, the poly (alkylene glycol) compounds used in the context of the present invention may comprise compounds consisting of polymerized epoxides, for example ethylene oxide (-O-CH ₂ -CH ₂ -, abbreviation: OE), propylene oxide (abbreviation: OP) and / or 1-butylene oxide (abbreviation: OB).

According to one aspect of the present invention, the poly (alkylene glycol) compound used in the continuous process of the present invention has a formula (I):

in which :

A represents a polymeric chain consisting of:

m alkylene oxide units of formula -O-CH ₂ -CHR ₄ - with R ₄ representing an alkyl group comprising from 1 to 4 carbon atoms, and m varying from

0 to 150,

p alkylene oxide units of formula -O-CH ₂ -CHRs- with R ₅ representing an alkyl group comprising from 1 to 4 carbon atoms, and p ranging from 0 to 150,

n ethylene oxide units -O-CH ₂ -CH ₂ - with n varying from 1 to 150,

m + n + p> 4 and

the alkylene oxide units of formula -O-CH ₂ -CHR ₄ -, alkylene oxide of formula -O-CH ₂ -CHR ₅ - and the units of ethylene oxide -O-CH ₂ -CH ₂ - are arranged alternately or statistically or in blocks; Ra represents a hydrocarbon chain, linear or branched, comprising from 1 to 100 carbon atoms, for example from 1 to 70, from 1 to 60, from 1 to 50 or from 1 to 30 carbon atoms.

According to another aspect of the present invention, the poly (alkylene glycol) compound used in the continuous process of the present invention has a formula (Γ):

(Γ) R ' _a - A' - OH

in which :

- A 'represents a polymer chain consisting of:

propylene oxide units of formula -O-CH ₂ -CH (-CH ₃ ) - and m 'varying from 0 to 150, for example from 1 to 100, from 1 to 50 or from 1 to 30; ,

ethylene oxide units -O-CH ₂ -CH ₂ - with n varying from 1 to 150, for example from 1 to 100, from 1 to 50 or from 1 to 30,

- m '+ n'> 4 and

the propylene oxide units -O-CH ₂ -CH (-CH ₃ ) - and the ethylene oxide units -O-CH ₂ -CH ₂ - are arranged alternately or randomly or in blocks;

- R'a represents a hydrocarbon chain, linear or branched having 1 to 100 carbon atoms, for example 1 to 50 or 1 to 10 carbon atoms. According to another aspect of the present invention, the poly (alkylene glycol) compound used in the continuous process of the present invention consists of polyethylene oxide units and / or polypropylene oxide units and have at their free end. an alkyl group comprising from 1 to 4 carbon atoms, which is a linear or branched chain.

According to the other embodiment, the poly (alkylene glycol) compound as represented in formulas (I) and (Γ) includes at least 80 mol%, for example at least 85 mol% of ethylene oxide groups. This gives a very good balance between hydrophobicity and hydrophilicity in the comb polymer obtained.

According to one aspect of the present invention, the esterification is carried out in the presence, besides the poly (alkylene glycol) compound of formula (I) or (Γ), of a poly (alkylene glycol) having a formula (II): (II) HO - [(CHR ₆ -CH ₂ -O) _r - (CHR ₇ -CH ₂ -O) _s - (CH ₂ -CH ₂ -O) _t ] - H

in which :

R _O and R _7i independently of one another represent an alkyl group comprising from 1 to 4 carbon atoms,

r and s, independently of one another, vary from 0 to 150,

t varies from 1 to 150,

- r + s + t> 4 and

the alkylene oxide units of the formula -CHR ₆ -CH ₂ -O-, the alkylene oxide of the formula -CHR ₇ -CH ₂ -O- and the ethylene oxide units -CH ₂ - CH ₂ -0- are arranged alternately or statistically or in blocks. According to one embodiment, the poly (alkylene glycol) having a formula (II) is present at a content of less than 5% by weight, relative to the total of the copolymer obtained at the end of the process, for example at a lower content or equal to 4% by weight or 3% by weight. According to another aspect of the present invention, the esterification is carried out in the presence, in addition to the poly (alkylene glycol) compound of formula (I) or (Γ), of a poly (alkylene glycol) having a formula (III) :

(III) HO - [(CH (-CH ₃ ) -CH ₂ -O) _u - (CH ₂ -CH ₂ -O) _v ] - H

in which :

u varies from 0 to 150,

- v varies from 1 to 150,

- u + v> 2 and - The propylene oxide units -O-CH ₂ -CH (-CH ₃ ) - and the ethylene oxide units -O-CH ₂ -CH ₂ - are arranged alternately or randomly or in blocks. Thus, according to this aspect of the present invention, the poly (alkylene glycol) compounds comprise polyethylene oxide units and / or polypropylene oxide units and have at their free end a hydroxide group.

Regardless of their free end (H or alkyl), the poly (alkylene glycol) compounds used in the context of the present invention may, for example, comprise a dominant proportion of ethylene-oxy group in combination with a secondary proportion of propylene group. oxy. Specific examples of the alkylene glycol polymer include: polyalkylene glycols having an average molecular weight of 1,000, 4,000, 6,000 and 10,000 g / mol; polyethylene polypropylenes glycols having a percentage of ethylene oxide of between 20 and 80% by weight and a percentage of propylene oxide of between 20 and 80% by weight. Such compounds are commercially available.

In yet another aspect of the present invention, the poly (alkylene glycol) compounds comprise a mixture:

poly (alkylene glycol) compounds comprising polyethylene oxide units and / or polypropylene oxide units and having at their free end an alkyl group comprising from 1 to 4 carbon atoms, which is a chain or branched, and

poly (alkylene glycol) compounds comprising polyethylene oxide units and / or polypropylene oxide units and having at their free end H.

Furthermore, the esterification process of the present invention takes place in the presence of at least one poly (alkylene glycol) introduced in powder form or in the molten state, for example using a hopper.

Antioxidant agent

In the context of the present invention, the use of an antioxidant agent, also called simply "antioxidant" or "thermal stabilizer", has solved one of the technical problems related to high temperatures used in continuous processes, in particular reactive extrusion, namely the degradation of the poly (alkylene glycol) raw materials and the cleavage of the pendant chains of the synthesized comb polymer. The use of an antioxidant agent maintains the expected quality of the polymer. Moreover, despite the reluctance related to the high temperatures and to the thermodegradability of the polyalkylene glycols, the minimum temperature of esterification and / or amidification existing in said tubular reactor, in particular the extruder, has been fixed at 170 ° C, which allows to significantly reduce the residence time in the reactor and thus improve the profitability of the polymer obtained.

The mode of action of antioxidants in polymer preparation processes varies with the structure and chemical composition of antioxidants. They are intended to slow down or prevent the oxidation of reagents or reaction products during the process. Generally, the antioxidants include heteroatoms, for example nitrogen atoms, which can lead to changes in the behavior of the polymers obtained in the applications. In the context of the present invention, the antioxidants are not intended to be incorporated into the comb structure polymer. Nevertheless, it is possible that some of these agents remain grafted onto the polymer, exceptionally and unexpectedly. In this case, the amounts of said agents are very small.

According to one aspect of the present invention, the antioxidant used in said esterification and / or amidification process comprises an aromatic amine, a phosphine group, an organophosphate group and / or a piperidine ring.

According to another aspect of the invention, the antioxidant is an amine having at least one aromatic group substituted by an alkyl chain. For example, the antioxidant comprises two aromatic groups, at least one of which is substituted with an alkyl chain having from 3 to 9 carbon atoms. For example, this is the compound with CAS number 68411-46-1. Irganox ™ 5057 sold by CIBA ™ is a commercial example of such a compound.

According to yet another aspect of the invention, the antioxidant is an organophosphate compound. For example, the antioxidant is an aromatic and / or aliphatic phosphite. For example, this is the compound whose CAS number is 25550-98-5 or 101-02-0. Doverphos ™ 7 and Doverphos ™ 10 marketed by the company DOVER ™ are commercial examples of such compounds.

According to another aspect of the invention, the antioxidant is selected from the group consisting of trimethyl dihydroquinoline polymer, diphenylamine derivatives, phenothiazine, phenyl-alpha-naphthylamine, 4,4'-methylene-bis-2, 6-di-tert-butylphenol, butylated hydroxyanisole (BHA), methoxyphenol (hydroxyanisole), dihydrobenzene (DHB), a compound of the family of hydroxyphenols (for example hydroquinone or pyrocatechol) or a mixture of these agents. Such agents are commercially available. Different Embodiments of the Esterification and / or Amidation Process

According to one embodiment of the present invention, the molar ratio between said poly (alkylene glycol) and said acid homopolymer or copolymer varies between 100: 1 and 1: 1, for example 50: 1 and 5: 1 or between 25: 1 and 10: 1.

According to another embodiment of the present invention, the esterification and / or amidification process uses from 1% to 30% by weight of (meth) acrylic acid polymer, for example from 2% to 20% of the polymer of the (meth) acrylic acid, and from 70% to 99% by weight of at least one poly (alkylene glycol) compound, for example from 80% to 98% of at least one poly ( alkylene glycol).

It is quite possible to use an esterification and / or amidation catalyst in the context of the present invention. For example, as an esterification and / or amidification catalyst, an alkaline or alkaline-earth salt of a strong protic acid, that is to say capable of releasing protons and having a pKa of less than 0, is used. .

For example, the catalyst is a salt of a strong protic acid having a hydrocarbon group. Alkyl sulphonic, aryl sulphonic or aryl alkyl sulphonic acid salts, such as the sodium, potassium, lithium, calcium and magnesium salts of para-toluene sulphonic acid, are more particularly mentioned.

The use of a strong neutralized protic acid makes it possible to improve the conversion rate of the poly (alkylenes glycols) without chain cleavage, while having a catalytic activity sufficient to promote the esterification / amidation reaction. Thus, it may, for example, be para toluene sulfonic acid, methanesulfonic acid, sulfuric acid, Lewis acid. Pentavalent phosphorus catalysts such as phosphoric acid (H ₃ PO ₄ ), phosphorous acid (H ₃ PO ₃ ), hypophosphorous acid (H ₃ PO ₂ ), phenylphosphinic acid (H ₂ PO ₃ ) are also mentioned. ₃ PI1), polyphosphoric acids such as phosphoric anhydride, tetrapolyphosphoric acid, pyrophosphoric acid (H ₄ P ₂ O ₇ ), trimetaphosphoric acid, phosphoric pentachloride, a phosphorous ester such as triphenyl phosphite ( P (OPh) ₃ ), a hypophosphite such as ammonium hypophosphite, sodium hypophosphite, boric acid and its derivatives such as boric anhydride (B ₂ O ₃ ), phosphoric anhydride (P ₂ O ₅ ) and pyrophosphoric acid (H4P2O7).

The esterification and / or amidation catalyst can be used in an amount of from 0.04% to 10% molar, based on the number of acid functions, for example carboxylic acid, of the acidic polymer. According to one aspect of the present invention, the continuous process comprises at least the following steps:

a) mixing said homopolymer or acidic copolymer and said at least one poly (alkylene glycol) in the molten state before introduction into said tubular reactor, in particular the extruder,

b) introducing the mixture of step a) into said tubular reactor, in particular the extruder,

c) the antioxidant is introduced during step a) and / or into said tubular reactor, in particular the extruder in one or more times, and

d) the esterification and / or amidation of said homopolymer / copolymer is carried out by hot reaction in the tubular reactor, for example in the mixing and transport zone of the extruder, optionally equipped with a system of removal of water, said esterification and / or amidification taking place at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification and / or amidation catalyst, optionally at reduced pressure and / or under a flow of inert gas.

In one embodiment, during step d), the mixing zone comprises a homogenization of the mixture.

In one embodiment, during step d), the esterification and / or amidation of said homopolymer / copolymer is carried out by hot kneading in the mixing and transport zone of the extruder, optionally equipped with a water removal system, said esterification and / or amidification taking place at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification and / or amidation catalyst, optionally under reduced pressure and / or under a flow of inert gas.

According to another aspect of the present invention, the continuous process comprises at least the following steps:

a) introducing the homopolymer or acid copolymer into the extruder, in dry form or in solution in water, one or more times during the process, b) introducing the poly (alkylene glycol) compound in solid form or in the molten state in said tubular reactor, in particular the extruder, in one or more times during the process,

c) introducing the antioxidant into said tubular reactor, in particular the extruder, one or more times during the process, and

d) the esterification and / or amidation of said homopolymer / copolymer is carried out by hot reaction in the tubular reactor, for example in the mixing and transport zone of the extruder, possibly equipped with an elimination system water, said esterification and / or amidification taking place at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification and / or amidation catalyst, optionally at reduced pressure and / or under a stream of inert gas. In one embodiment, during step d), the mixing zone comprises a homogenization of the mixture.

In one embodiment, during step d), the esterification and / or amidification of said homopolymer / copolymer is carried out by hot kneading in the mixing and transport zone of the extruder, optionally equipped with a water removal system, said esterification and / or amidification occurring at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification and / or amidation catalyst, optionally at pressure reduced and / or under a stream of inert gas. Comb polymer obtained by the process of continuous esterification and / or amidification

Another object of the present invention relates to the polymer, having a hydrocarbon chain and poly (oxyalkylated) side groups, also called comb polymer, obtainable by the continuous process described above. According to one aspect of the present invention, said polymer having a hydrocarbon chain and poly (oxyalkylated) side groups obtained by the continuous esterification and / or amidation process has a molecular weight Mw of between 15,000 and 400,000 g. / mol, for example between 20 000 and 200 000 g / mol, between 25 000 and 150 000 g / mol or between 30 000 and 125 000 g / mol.

According to one aspect of the present invention, this polymer has an IP polydispersity index of less than 2.5, for example less than 2.

According to one aspect of the present invention, this polymer has an IP polydispersity index of less than 2.5, for example less than 2 or 1.6.

Despite the high temperatures used, the process of the present invention makes it possible to obtain a comb polymer having a low IP polydispersity index. The technical characteristics of the process are such that the rate of degradation of the side chains and the degree of crosslinking are indeed very low. The method of the present invention thus makes it possible to obtain a polymer of better quality, while improving the production yield. Thus, according to one embodiment of the present invention, the comb polymer thus obtained is characterized in that it has a degree of polymeric purity such that the content of free poly (alkylene glycol) is less than 15% by weight (by relative to the total weight introduced into the reactor), as measured by CES (see details below).

According to another embodiment of the present invention, the comb polymer thus obtained is characterized in that it has a degree of polymeric purity such that the content of free poly (alkylene glycol) is less than 13% by weight (relative to to the total weight introduced into the reactor), as measured by HPLC.

Steric exclusion chromatography (CES) or in English "Gel Permeation Chromatography" (GPC) also makes it possible to measure the molecular mass at the highest peak Mp (in English "molecular weight of the highest peak" or "peak molecular weight Mp ").

The molecular weights Mp are expressed in g / mol.

In the context of the present invention, the measured molecular weight ratio Mp / theoretical molecular weight Mp can be calculated. The calculation of such a ratio makes it possible in particular to evaluate the efficiency of the process of the present invention.

The molecular weight Mp of the comb polymer (PP) obtained by the process of the present invention is measured by CES. This quantity is called MPM _PP in the context of the present invention.

The theoretical molecular weight Mp of the comb polymer (PP) is calculated according to the following formula. This quantity is called Mpt _PP in the context of the present invention.

The theoretical molecular weight Mp of the comb polymer (PP) is calculated according to the following formula:

Mptpp ~ "P

in which :

Mpt _PP is the theoretical molecular weight Mp of the comb polymer (PP),

Mp _PAL is the molecular weight Mp of the acidic polymer (PAL),

Mp _PAG is the molecular weight Mp of polyalkylene glycols (PAG),

N _PAL is the number of moles of acidic polymers introduced into the reactor,

N _PAG is the number of moles of poly (alkylene glycol) introduced into the reactor, N _res is the number of moles of residual poly (alkylene glycol) measured by CES at the reactor outlet.

According to one embodiment, the comb polymer obtained is such that the ratio Mp measured / Mp theoretical is between 0.3 and 3, for example between 0.5 and 2.

According to another embodiment, the comb polymer obtained is such that the ratio Mp measured / theoretical Mp is between 0.8 and 1.2, for example between 0.85 and 1.15 or between 0.9 and 1 1.

According to another embodiment, the comb polymer obtained is such that the Mpmpp / Mptpp ratio is between 0.8 and 1.2.

The inventors have indeed realized that, according to these embodiments, the process conditions are such that it tends to a rate of use of polyalkylene glycols introduced into the extruder close to 100%. In addition, it is ensured that the degradation rate of these polyalkylene glycols, as well as pendant chains grafted onto the acidic polymer, tends to 0%. In addition, thermal crosslinking inducing crosslinking is limited, so that the measured Mp tends to the theoretical Mp when the grafting rate of polyalkylene glycols tends to 100%.

The comb polymer thus obtained can be used as an adjunct for hydraulic composition.

In order to facilitate its implementation and the assay, the adjuvant can be presented as a solution in a suitable solvent. Preferably, the appropriate solvent comprises or consists of water. In some cases, the addition of another solvent, such as an alcohol or a glycol may be considered in addition or alternatively, for example to facilitate solubilization. The concentration of the adjuvant polymer depends mainly on the intended application. Generally, the formulation of the adjuvant comprises 1 to 50% by weight, preferably 10 to 40% by weight of polymer relative to the total weight. Process for the preparation of the comb polymer by polymerization then esterification / amidification

Another subject of the present invention relates to a process for preparing a comb polymer, said process comprising the following steps:

a) preparation of an acid homopolymer or copolymer, for example a homopolymer or copolymer of (meth) acrylic acid, by controlled radical polymerization,

b) esterification / continuous amidation of said homopolymer or acidic copolymer obtained according to step a), as described above, in the presence of at least one poly (alkylene glycol) in solid or melt form and an antioxidant, to obtain said comb polymer,

c) optionally, solubilization of the comb polymer obtained according to step b), d) optionally, complete or partial neutralization of the comb polymer obtained according to step b) and / or c),

e) optionally, powdering the comb polymer obtained according to step b) and / or c) and / or d).

Thus, according to step a) of this process, said homopolymer or acidic copolymer is prepared by controlled radical polymerization, as described above.

According to one embodiment of the present invention, in said process for preparing a comb polymer, the steps c) of solubilization and d) of neutralization are combined. Thus said process comprises the following steps:

b) esterification / continuous amidation of said homopolymer or acidic copolymer obtained according to step a), as described above, in the presence of at least one poly (alkylene glycol) in solid form or in the molten state, and an antioxidant, to obtain said comb polymer,

c ') solubilization and neutralization of the comb polymer obtained according to step b), d) optionally powdering the comb polymer obtained according to step c'). Comb polymer obtained by the continuous polymerization and esterification / amidation process

Another subject of the present invention relates to a polymer having a hydrocarbon chain and poly (oxyalkylated) side groups, also called comb polymer, obtainable by the polymerization and esterification and / or amidification process described above. .

The present invention also relates to the dispersant additive for hydraulic composition comprising the comb polymer, as described above, obtainable by the polymerization and esterification / amidation process described above.

Finally, the subject of the present invention is the use of a polymer also called comb polymer, obtainable by the polymerization process and esterification / amidation described above, to reduce the water content of the hydraulic compositions.

The examples which follow make it possible to better understand the present invention without limiting its scope.

EXAMPLES

Molecular weight homopolymer or acid copolymer Mw and Mp

Such a technique implements a WATERS ™ brand liquid chromatography apparatus equipped with a detector. This detector is a WATERS ™ refractometric concentration detector.

This liquid chromatography apparatus is provided with a steric exclusion column appropriately chosen by those skilled in the art in order to separate the different molecular weights of the polymers studied. The liquid elution phase is an aqueous phase adjusted to pH 9 with 1N sodium hydroxide containing 0.05M NaHCO ₃ , 0.1M NaNO ₃ , 0.02M trietanolamine and 0.03% NaN ₃ .

In a detailed manner, according to a first step, the polymerization solution is diluted to 0.9% dry in the solubilization solvent of the CES, which corresponds to the liquid phase of elution of the CES to which 0.04% is added. of dimethylformamide which acts as a flow marker or internal standard. Then filtered at 0.2 μιη. 100% are then injected into the chromatography apparatus (eluent: an aqueous phase adjusted to pH 9.00 with 1N sodium hydroxide containing 0.05M NaHCO ₃ , 0.1M NaNO ₃ , 0.02M trietanolamine and 0 , 03% NaN ₃ ).

The liquid chromatography apparatus contains an isocratic pump (WATERS ™ 515) with a flow rate of 0.8 ml / min. The chromatography apparatus also comprises an oven which itself comprises in series the following column system: a precolumn of the GUARD COLUMN ULTRAH type YDRO GEL WATERS ™ of 6 cm long and 40 mm inside diameter, and a column of type ULTRAHYDROGEL WATERS ™ 30 cm long and 7.8 mm inside diameter. The detection system consists of a RI WATERS ™ 410 type refractometric detector. The oven is heated to a temperature of 60 ° C and the refractometer is heated to a temperature of 45 ° C.

The chromatography apparatus is calibrated by standards of powdered polyacrylate of various molecular weights certified by the supplier: POLYMER STANDARD SERVICE or AMERICAN POLYMER STANDARDS CORPORATION. Polymer molecular weight comb Mw and Mp

In each of the following examples, the molecular weight of the comb polymers according to the invention is determined by CES.

One such technique uses a WATERS ™ brand liquid chromatograph with two detectors, one of which combines the static scattering of light at 90 ° C to the viscometry measured by one MALVER ™ detector and the other. being a WATERS ™ refractometric concentration detector.

This liquid chromatography apparatus is provided with steric exclusion columns appropriately chosen 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 K 0 ₃ .

In a detailed manner, the polymerization solution is diluted to 0.9% in the eluent of the CES, and then filtered at 0.2 μιη. 100 are then injected into the CES apparatus. The eluent of the CES is a 1% solution of KN0 ₃ . The liquid chromatography apparatus contains an isocratic pump (Waters 515) with a flow rate of 0.8 ml / min, a furnace containing the following column system as standard: a 6 cm GUARD COLUMN ULTRAHYDROGEL WATERS ™ precolumn long and 40 mm internal diameter, one column ULTRAHYDROGEL WATERS ™ type 30 cm long and 7.8 mm inside diameter and two columns ULTRAHYDROGEL 120 ANGSTROM WATERS ™ 30 cm long and 7.8 mm inside diameter and then comes in parallel the detection system: on one side a refractometric detector type RI WATERSTM 410 and on the other side a dual detector viscometer and light scattering at a 90 ° angle of 270 type DUAL DETECTOR MALVERN ™ . The oven is heated to 55 ° C, and the refractometer is heated to 45 ° C.

The CES device is calibrated by a universal / multidetector type calibration by a single standard of PEV 19k type PolyCAL ™ MALVERN ™ with the following characteristics are known: concentration, IV, Mw, Mn, PI, thus allowing to calibrate each detector. Acid number of a polymer

The acid number of the polymer is determined by acid-base measurement by dissolving 1 g of polymer in 100 g of methanol and then titrating the solution with 1 N of aqueous KOH solution using an automatic titrator.

The acid number is measured in mg KOH / g, that is to say, mass of KOH necessary to neutralize the acidity of the polymer.

Free Polyalkylene Glycol Content)

Determined by CES as described above. Example 1

This example illustrates the reactive extrusion condensation of a homopolymer of methacrylic acid with a methoxy poly (ethylene glycol) (MPEG) of molecular weight 5,000 g / mol (commercially available).

A TSA® corotative twin-screw extruder is used, the geometric parameters of which are as follows:

Diameter = 26 mm and Length / Diameter = 80, equipped with a gas evacuation device.

The rates of introduction of the reagents into the extruder are adjusted so that the masses introduced are proportional to the following values:

1.063 kg of a homopolymer of methacrylic acid (Mw = 7 700 g / mol, Mw = 10 000 g / mol, IP = 3) in powder form,

4.899 kg of methoxy poly (ethylene glycol) with a molecular weight of 5000 g / mol in the molten liquid state at 80 ° C.,

14.8 g of lithium hydroxide (esterification catalyst), and

- 12 g Irganox® 5057 antioxidant.

The flow rates are then proportionally modified to adjust the residence time in the extruder. Said residence time is measured by adding a colored tracer. Thus, the molar ratio between MPEG and the acidic homopolymer is 7.1: 1.

The extruder has a reaction zone whose temperature is set at 220 ° C. The flow rate is set so that the residence time of the reagents and products in the extruder is 25 minutes ± 1.

The product obtained at the extruder outlet is in the form of a molten resin. The product is then solubilized by adding water and then neutralized by adding NaoH (50%) to pH = 8.5.

Characterization of the polymer obtained

Acid number = 89 mg KOH / g.

MPr pp = 40,300 g / mol.

Mpt pp = 35,617 g / mol.

Ratio Mpm pp / Mpt pp = 1.13.

IP = 1.6.

Mw = 190,300 g / mol.

Free MPEG content at the reactor outlet = 13.4%. Example 2

This example illustrates the reactive extrusion condensation of a homopolymer of methacrylic acid with a methoxy poly (ethylene glycol) (MPEG) of molecular weight 2,000 g / mol (commercially available).

The ingredients are continuously fed into a TSA® corotative twin-screw extruder (Diameter = 26 mm and Length / Diameter = 80, equipped with a gas evacuation device).

1.33 kg of a homopolymer of methacrylic acid (Mw = 7 700 g / mol, Mw = 10 000 g / mol, IP = 3) in powder form,

4.64 kg of methoxy poly (ethylene glycol) with a molecular weight of 2,000 g / mol in the molten liquid state at 80 ° C.

21 g of lithium hydroxide, and

- 18 g Irganox® 5057 antioxidant.

The flow rates are then proportionally modified to adjust the residence time in the extruder. Said residence time is measured by adding a colored tracer. Thus, the molar ratio between MPEG and the acidic homopolymer is 13.4: 1.

The extruder has a reaction zone whose temperature is set at 220 ° C. The flow rate is set so that the residence time of the reagents and products in the extruder is 24 minutes ± 1.

The product obtained at the extruder outlet is in the form of a molten resin. The product is then solubilized by adding water and neutralized with sodium hydroxide (50%) until a solids content of 41.1% by weight is obtained.

Characterization of the polymer obtained

MPa pp = 45,000 g / mol.

Mpt pp = 29,300 g / mol.

Ratio Mpm pp / Mpt pp = 1.5.

IP = 1.9.

Mw = 88,000 g / mol.

Acid number = 126 mg KOH / g.

Free MPEG content at reactor outlet = 3.2%. Example 3

This example illustrates the reactive extrusion condensation of a homopolymer of methacrylic acid with a methoxy poly (ethylene glycol) (MPEG) of molecular weight 2,000 g / mol (commercially available). The ingredients are continuously fed into a TSA® corotative twin-screw extruder (Diameter = 26 mm and Length / Diameter = 80, equipped with a gas evacuation device).

1.82 kg of a homopolymer of methacrylic acid (Mw = 7 700 g / mol, Mw = 10 000 g / mol, IP = 3) in powder form,

4.186 kg of methoxy poly (ethylene glycol) with a molecular weight of 2,000 g / mol in the molten liquid state at 80 ° C.,

- 10 g Irganox® 5057 antioxidant.

The flow rates are then proportionally modified to adjust the residence time in the extruder. Said residence time is measured by adding a colored tracer. Thus, the mole ratio between MPEG and acidic rhomopolymer is 8.8: 1. The extruder has a reaction zone whose temperature is set at 220 ° C. The flow rate is set so that the residence time of the reagents and products in the extruder is 30 minutes ± 1.

The product obtained at the extruder outlet is in the form of a molten resin. The product is then solubilized by adding water and neutralized with sodium hydroxide (50%) until a solids content of 40.4% by weight is obtained. Characterization of the polymer obtained

MPa pp = 41,000 g / mol.

Mpt pp = 23,662 g / mol.

Ratio Mpm pp / Mpt pp = 1.7.

IP = 1.8.

Free MPEG content at the reactor outlet = 13%.

Acid number = 165 mg KOH / g.

Example 4

0.42 kg of a homopolymer of methacrylic acid (Mw = 7 700 g / mol, Mw = 10 000 g / mol, IP = 3) in powder form, 5.54 kg of methoxy poly (ethylene glycol) with a molecular weight of 5000 g / mol in the molten liquid state at 80 ° C.,

14 g of lithium hydroxide, and

- 12 g Irganox® 5057 antioxidant.

The flow rates are then proportionally modified to adjust the residence time in the extruder. Said residence time is measured by adding a colored tracer. Thus, the molar ratio between MPEG and acidic rhomopolymer is 20: 1. The extruder has a reaction zone whose temperature is set at 220 ° C. The flow rate is set so that the residence time of the reagents and products in the extruder is 30 minutes ± 1.

The product obtained at the extruder outlet is in the form of a molten resin. The product is then solubilized by adding water and neutralized with sodium hydroxide (50%) until a solids content of 40.3% by weight is obtained.

Characterization of the polymer obtained

MPa pp = 147,000 g / mol.

Mpt pp = 86,070 g / mol.

Ratio Mpm pp / Mpt pp = 1.7.

IP = 1.7.

Mw = 103,000 g / mol.

Free MPEG content at the reactor outlet = 15%.

Acid number = 39 mg KOH / g.

Example 5

This example illustrates the reactive extrusion condensation of a homopolymer of acrylic acid with a methoxy poly (ethylene glycol) (MPEG) of molecular weight 2,000 g / mol (commercially available).

1.23 kg of a homopolymer of acrylic acid (Mw = 12000 g / mol, IP = 2.8) in powder form,

4.72 kg of methoxy poly (ethylene glycol) with a molecular weight of 2,000 g / mol in the molten liquid state at 80 ° C.

26 g of lithium hydroxide, and

- 21 g Irganox® 5057 antioxidant. The flow rates are then proportionally modified to adjust the residence time in the extruder. Said residence time is measured by adding a colored tracer. The extruder has a reaction zone whose temperature is set at 220 ° C. The flow rate is set so that the residence time of the reagents and products in the extruder is 30 minutes ± 1.

The product obtained at the extruder outlet is in the form of a molten resin. The product is then solubilized by adding water and neutralized with sodium hydroxide (50%) until a solids content of 39.3% by weight is obtained. Characterization of the polymer obtained

MPa pp = 55,000 g / mol

Mpt pp = 63,000 g / mol

Ratio Mpm pp / Mpt pp = 0.9

IP = 1.5

Free MPEG content at the outlet of the reactor = 9%

Acid number = 136 mg KOH / g.

Example 6

This example illustrates the use of the polymers obtained according to Examples 1 to 5 in a mortar composition whose constitution is given in Table 1 below. The workability of the composition is measured at T0. It is demonstrated that the polymers prepared according to the process of the present invention can be qualified as water reducers.

Measurement of the handling of the mortar (slump)

Maneuverability measurements, also known as sag measurements, are performed at room temperature using a frustoconical, frustoconical, galvanized steel cone called a mini Abrams cone. This cone has the following characteristics:

Upper diameter: 50 ± 2 mm.

Lower diameter: 100 ± 2 mm.

Height: 150 ± 2 mm.

The cone is placed on a plate moistened with a sponge.

The cone is then filled with a determined quantity of each of the preparations. The filling lasts 2 minutes. The contents of the cone are packed with a metal rod.

Measuring air capture

The measurement of air capture is in accordance with EN 12350-7, paragraph 3.3. Mortar tests

Examples 1 to 5 are tested on a mortar formulation according to EN 196-1 by mixing with stirring, standardized sand (EN 196-1), cement (CEM I 52.5 N), water and a dispersant additive according to the invention. The proportions are given in Table 1 below.

Table 1

The workability is measured at T0 using the test described in the preamble adapted to the mortar (mini-cone of Abrams) and the air capture of each of the mortar preparations. The results obtained are shown in Table 2 below.

Table 2

Test 1-1 is a negative control. It illustrates a reference mortar composition without adjuvant, that is to say without dispersant additive according to the invention.

In the tests 1-2 to 1-6 according to the invention, the use of a dispersant additive reduces the amount of water in the hydraulic composition while maintaining initial handling similar to that of the negative control. The dispersant additive may be described as a high water reducer in accordance with the standard ADJUVANT NF EN 934-2 according to which is qualified as "high water reducer" or "superplasticizer" an adjuvant that allows a reduction of water for the water. additive concrete> 12% over control concrete. It should be noted that the air capture percentages measured for tests 1-2 to 1-6, although greater than 1-1, are quite acceptable given the presence of the polymer in formulations.

Claims

1. A continuous process for preparing a comb polymer, without an organic solvent, by esterification and / or amidification of an acidic homopolymer or copolymer, comprising performing the esterification and / or amidation of said homopolymer / copolymer by reaction with in the mixing and conveying zone of a tubular reactor, for example in the mixing and transport zone of an extruder, possibly equipped with a water elimination system, in the presence of at least one a poly (alkylene glycol) in solid or melt form and an antioxidant, said esterification and / or amidification occurring at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification catalyst and / or amidifïcation, optionally under reduced pressure and / or under a flow of inert gas.

The continuous process according to claim 1, wherein said acid homopolymer or copolymer results from the polymerization or copolymerization of at least one of the monomers selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid , crotonic acid, fumaric acid and maleic anhydride.

3. Continuous process according to any one of the preceding claims, wherein said poly (alkylene glycol) has a formula (I):

in which :

A represents a polymeric chain consisting of:

m alkylene oxide units of formula -O-CH ₂ -CHR ₄ - with R ₄ representing an alkyl group comprising from 1 to 4 carbon atoms, and m ranging from 0 to 150,

p alkylene oxide units of formula -O-CH ₂ -CHR ₅ - with R ₅ representing an alkyl group comprising from 1 to 4 carbon atoms, and p ranging from 0 to 150, n oxide units; ethylene -O-CH ₂ -CH ₂ - with n ranging from 1 to 150,

m + n + p> 4 and

the alkylene oxide units of formula -O-CH ₂ -CHR ₄ -, alkylene oxide of formula -O-CH ₂ -CHR ₅ - and the units of ethylene oxide -O-CH ₂ -CH ₂ - are arranged alternately or statistically or in blocks;

Ra represents a hydrocarbon chain, linear or branched having from 1 to 100 carbon atoms.

4. The continuous process according to claim 3, wherein the esterification and / or amidification is carried out in the presence, in addition, of a poly (alkylene glycol) having a formula (II):

(II) HO - [(CHR6-CH ₂ -O) _r - (CHR ₇ -CH ₂ -O) _s - (CH ₂ -CH ₂ -O) _t ] - H

in which :

r and s, independently of one another, vary from 0 to 150,

t varies from 1 to 150,

- r + s + t> 4 and

the alkylene oxide units of the formula -CHR6-CH ₂ -O-, the alkylene oxide of the formula -CHR ₇ -CH ₂ -O- and the ethylene oxide units -CH ₂ -CH ₂ -0- are arranged alternately or statistically or in blocks.

5. Continuous process according to claim 4, wherein the poly (alkylene glycol) having a formula (II) is present at a content of less than 5% by weight, relative to the total of the copolymer obtained at the end of the process.

6. Continuous process according to any one of the preceding claims, wherein said homopolymer or acid copolymer to be esterified and / or amidified is in the form of an aqueous solution.

7. Continuous process according to any one of claims 1 to 5, wherein said acid homopolymer or copolymer to be esterified and / or amidified is in dry form.

8. A continuous process according to any one of the preceding claims, wherein said acid homopolymer or copolymer to be esterified and / or amidified is a polymer of acrylic acid and / or methacrylic acid of molecular weight Mw between 1 000 and 20,000 g / mol, as determined by GPC.

9. Continuous process according to any one of the preceding claims, wherein said homopolymer or acidic copolymer has a polydispersity index IP (Mw / Mn ratio) of between 1.5 and 3.

The continuous process according to any one of the preceding claims, wherein the antioxidant comprises an aromatic amine, a phosphine group, an organophosphate group and / or a piperidine ring.

11. The continuous process as claimed in any one of the preceding claims, in which the molar ratio between said poly (alkylene glycol) and said acid homopolymer or copolymer varies between 100: 1 and 1: 1, for example 50: 1 and 5: 1. or between 25: 1 and 10: 1.

12. Continuous process according to any one of the preceding claims, wherein the tubular reactor comprises a plurality of reaction zones having different temperatures ranging between ambient temperature and 250 ° C, of which at least one reaction zone having a temperature greater than or equal to 170 ° C. ° C.

13. Continuous process according to any one of the preceding claims, comprising at least the following steps:

a) mixing said homopolymer or acid copolymer and said at least one poly (alkylene glycol) in the molten state before introduction into the tubular reactor, b) introducing the mixture of step a) into the tubular reactor,

c) the antioxidant is introduced during step a) and / or into the tubular reactor in one or more times, and

d) the esterification and / or the amidation of said homopolymer / copolymer is carried out by hot kneading in the mixing and transport zone of the tubular reactor, possibly equipped with a water elimination system, said esterification and / or or amidification occurring at a temperature greater than or equal to 170 ° C, optionally in the presence of an esterification catalyst and / or amidifïcation, optionally under reduced pressure and / or under a flow of inert gas.

14. The continuous process according to any one of the preceding claims, wherein the tubular reactor is an extruder.

15. Polymer having a hydrocarbon chain and polyoxyalkyl side groups, obtainable by the continuous esterification and / or amidification process according to any one of claims 1 to 14, having an IP polydispersity index of less than 2. For example less than 2 or 1.6 '.

16. A process for preparing a comb polymer, said method comprising the following steps:

a) preparation of an acid homopolymer or copolymer by controlled radical polymerization,

b) esterification / continuous amidation of said homopolymer / copolymer obtained according to step a), in the presence of at least one poly (alkylene glycol) in solid or melt form and an antioxidant, according to one of any of claims 1 to 14,

c) optionally, solubilization of the polymer obtained according to step b),

d) optionally, total or partial neutralization of the polymer obtained according to step b) and / or c),

e) optionally, powdering the polymer obtained according to step b) and / or c) and / or d).

17. A comb polymer obtainable by the process of claim 16 having an IP polydispersity index of less than 2.5, for example less than 2 or 1.6.

18. Dispersing additive for hydraulic composition comprising the comb polymer, according to claim 15 or 17.

19. Use of a comb polymer, according to claim 15 or 17, for reducing the water content of the hydraulic compositions.