EP3544937A1

EP3544937A1 - Production of dispersants by nitroxide-mediated solution polymerization

Info

Publication number: EP3544937A1
Application number: EP17807800.2A
Authority: EP
Inventors: Jürg WEIDMANN; Fabia ULBER; Jörg ZIMMERMANN
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2016-11-22
Filing date: 2017-11-21
Publication date: 2019-10-02
Also published as: US11028213B2; CN110023265B; CN110023265A; US20200071444A1; US20210261711A1; WO2018095926A1

Abstract

The present invention relates to methods for producing a copolymer, in particular a dispersant for solid particles, especially a dispersant for mineral binder compositions, wherein ionizable monomers m1 and sidechain-carrying monomers m2 are polymerized by nitroxide-mediated solution polymerization to a copolymer, the polymerization being carried out in the presence of an agent comprising a carboxy group-carrying and phosphorized alkoxyamine.

Description

Preparation of dispersants by nitroxide-mediated solution polymerization

Technical Field This invention relates to a process for preparing a solid particle dispersant, in particular a mineral binder dispersant, wherein ionizable monomers m1 and side chain-carrying monomers m2 are polymerized to a copolymer and to correspondingly available copolymers. Furthermore, the invention relates to the use of copolymers and mineral binder composition and formed therefrom molded articles comprising copolymers.

State of the art

Dispersing agents or flow agents are used, in particular in the construction industry, as liquefiers or as water-reducing agents for mineral binder compositions, such as e.g. Concrete, mortar, cements, plaster and lime, used. The dispersants are generally organic polymers which are added to the make-up water or added as a solid to the binder compositions. As a result, both the consistency of the binder composition during processing and the properties in the cured state can be advantageously changed.

Polycarboxylate-based comb polymers (PCE), for example, are known as particularly effective dispersants. Such comb polymers have a polymer backbone and side chains attached thereto. Corresponding polymers are described, for example, in EP 1 138 697 A1 (Sika AG). In order to produce comb polymers with a defined structure, in particular, the preparation via free radical polymerization reactions is suitable. Different and reactive monomers (side-chain monomers and anchor group monomers) are synthesized by means of an initiator and a regulator in one ner polymerization reaction implemented. As a result, for example, copolymers with block and / or gradient structures can be produced in a simple manner, which enables a targeted adaptation to different purposes. A corresponding method is described, for example, in Patent Application No. 15 186 756 (Sika Technology AG).

Depending on the polymerization used in free radical polymerization but under certain circumstances environmentally hazardous chemicals (Cu salts, halides, bipyridines) can be used (often used in RAFT or atom transfer radical polymerizations) or relatively expensive or difficult to obtain polymerization aids are required (eg in ATPR or reversible addition fragmentation chain transfer polymerization).

There is therefore still a need for improved production processes and dispersants obtainable therefrom which do not have the stated disadvantages.

Presentation of the invention

The object of the invention is therefore to overcome the disadvantages mentioned above. In particular, improved processes and dispersants, in particular for solid particles, and in particular for mineral binder compositions, are to be provided. The process should allow the most flexible and controlled production of the dispersants, so that a targeted adaptation to different fields of application or purposes is made possible. At the same time the production processes should be feasible as far as possible without polluting or expensive substances but still allow the most efficient production of dispersants. In particular, the dispersants obtainable in this way should enable effective liquefaction and good processing of mineral binder compositions. In particular, the effect of the dispersant should be maintained over as long as possible. Surprisingly, it has been found that this object can be achieved by the features of independent claim 1.

The core of the invention is accordingly a process for the preparation of a copolymer, in particular a dispersant for solid particles, in particular a dispersant for mineral binder compositions, wherein ionizable monomers m1 and side chain-carrying monomers m2 are polymerized to a copolymer by nitroxide-mediated solution polymerization. The polymerization is carried out in the presence of an agent comprising a carboxy group-carrying and phosphated alkoxyamine.

It has been found that by nitroxide-mediated solution polymerization with an agent comprising a carboxy group-carrying and phosphorous alkoxyamine, the polymer structure as well as the sequence of the polymer building blocks can be effectively calculated, changed and / or controlled. As a result, for example, copolymers with block and / or gradient structures can be produced in a simple manner. In addition, copolymers which have a relatively narrow molecular weight distribution or polydispersity result. The production process according to the invention permits production directly in an aqueous solution without significant amounts of environmentally problematic substances having to be added. Since a solution polymerization according to the invention is carried out, emulsifiers or stabilizers can be largely dispensed with. It has also been found that the agents used according to the invention are obtainable relatively inexpensively and in sufficient quantities. Dispersants and copolymers can thus be produced in an efficient process in a variety of modifications in a reliable and flexible manner cost-effective and environmentally friendly.

In comparison with known dispersants, dispersants prepared according to the invention have very good liquefaction effects in mineral binder compositions. This also remains relatively long maintained. Although the production of polymers by NMP technology in other contexts is known, it is surprising that when using the relatively inexpensive inventive agent in a Lösungspolymerisationsverfahren also sterically demanding copolymers can be prepared which as a dispersant for solid particles and in particular for mineral binder compositions are suitable.

Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of the dependent claims. Ways to carry out the invention

A first aspect of the present invention relates to a process for producing a copolymer, in particular a solid particle dispersant, in particular a mineral binder dispersant, wherein ionizable monomers m1 and side chain-carrying monomers m2 are polymerized to a copolymer by nitroxide-mediated solution polymerization, wherein the polymerization is carried out in the presence of an agent comprising a carboxy group-carrying and phosphorous alkoxyamine.

Another aspect of the present invention relates to a copolymer which is obtainable by the process according to the invention.

The structure of the copolymers can be analyzed and determined, for example, by nuclear magnetic resonance spectroscopy (NMR spectroscopy). In particular, by ¹ H and ¹³ C NMR spectroscopy can be determined in a conventional manner due to neighboring group effects in the copolymer and based on statistical evaluations see the sequence of the monomer units in the copolymer.

By the terms "ionizable monomers" and "ionizable monomer units" is meant in particular monomers or polymerized monomers which are present at a pH> 10, in particular at a pH> 12, in anionic form or negatively charged. These are especially H- Donor groups or acid groups. The ionizable groups are particularly preferably acid groups, such as, for example, carboxylic acid, sulfonic acid, phosphoric acid and / or phosphonic acid groups. Preferred are carboxylic acid groups. The acid groups may also be present as anions in deprotonated form or as a salt with a counterion or cation.

Inventive Production Method

The polymerization takes place in the present case by nitroxide-mediated solution polymerization.

The nitroxide-mediated polymerization (NMP) is known per se to the person skilled in the art in other contexts and represents a variant of the "living free radical polymerization" or the "controlled free radical polymerization".

Radical polymerization can basically be divided into three steps: initiation, growth, and termination. "Living Free Radical Polymerization" or "Controlled Free Radical Polymerization" refers to chain growth processes in which essentially no chain termination reactions (transfer and termination) occur. The living free radical polymerization thus takes place essentially in the absence of irreversible transfer or termination reactions. These criteria can be met, for example, when the polymerization initiator is consumed very early in the polymerization and there is an exchange between the different reactive species which proceeds at least as fast as the chain propagation itself. The number of active chain ends remains particularly during the polymerization essentially constant. This allows a substantially simultaneous growth of the chains throughout the polymerization process. This results in a corresponding narrow molecular weight distribution or polydispersity.

In other words, controlled radical polymerization or living-radical polymerization is characterized in particular by reversible or even absent termination or transfer reactions. After the initiation Accordingly, the active centers are maintained throughout the reaction. All polymer chains are formed (initiated) simultaneously and grow continuously over the entire time. The radical functionality of the active center is ideally retained even after complete conversion of the monomers to be polymerized. This special property of controlled polymerizations makes it possible to produce well-defined structures such as gradient or block copolymers by the sequential addition of different monomers.

In contrast, in traditional free radical polymerization, all three steps (initiation, growth, and termination) occur in parallel. The lifetime of the active, growing chains is very low and the monomer concentration during the chain growth of a chain remains essentially constant. The polymer chains thus formed have no active centers which are suitable for addition of further monomers. Thus, this mechanism does not allow control over the structure of the polymers. The preparation of gradient or block structures by means of conventional free-radical polymerization is therefore usually not possible (see, for example, "Polymers: Synthesis, Synthesis and Properties"; authors: Koltzenburg, Maskos, Nuyken; publisher: Springer Spektrum; ISBN: 97-3 - 642-34772-6 and "Fundamentals of Controlled / Living Radical Polymerization", publisher: Royal Society of Chemistry editors: Tsarevsky, Sumerlin, ISBN: 978- 1 -84973-425-7).

Thus, the "living free radical polymerization" clearly differs from the conventional "free radical polymerization" or the non-living or uncontrolled carried out free polymerization.

In nitroxide-mediated polymerization (NMP), nitroxides react reversibly with the active chain end to form a so-called dormant species. The equilibrium between active and inactive chain ends is strongly on the side of the dormant species, whereby the concentration of active species is very low. The probability that two active chains meet and cancel is thus minimized. For example, 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO) is known as an NMP agent. According to the invention, a nitroxide-mediated polymerization is carried out as a nitroxide-mediated solution polymerization. This means that all monomers and the copolymers formed are present dissolved in the solvent or the reaction solution during the nitroxide-mediated polymerization. In particular, therefore, no disperse phases, emulsions and / or suspensions are present during the polymerization reaction. The addition of stabilizers, phase stabilizers and / or emulsifiers is preferably dispensed with.

The side-chain-carrying monomers m2 include in particular polyalkylene oxide side chains, preferably polyethylene oxide and / or polypropylene oxide side chains.

The ionizable monomers m1 preferably comprise acid groups, in particular carboxylic acid, sulfonic acid, phosphoric acid and / or phosphonic acid groups. In particular, the ionizable monomers m1 have a structure according to the formula I:

The side chain-carrying monomers m2 preferably have a structure according to the formula II:

in which

R ¹ , each independently of one another, is -COOM, -SO 2 -OM, -O-PO (OM) ₂ and / or -PO (OM) ₂ ,

R ² , R ³ , R ⁵ and R ⁶ , each independently of one another, are H or an alkyl group having 1 to 5 carbon atoms,

R ⁴ and R ⁷ , each independently of one another, are H, -COOM or an alkyl group having 1 to 5 carbon atoms, or where R ¹ forms a ring with R ⁴ to -CO-O-CO-,

M independently represents H ⁺ , an alkali metal ion, an alkaline earth metal ion, a divalent or trivalent metal ion, an ammonium ion or an organic ammonium group; m = 0, 1 or 2, p = 0 or 1,

X, each independently of one another, is -O- or -NH-, R ^{8 is} a group of the formula - [AO] _n -R ^a , where A = C 2 - to C 4 -alkylene, R ^{a is} H, a C 1 - to C2o-alkyl group, - cycloalkyl group or -Alkylarylgruppe, and n = 2 - 250, in particular 10 - 200 is. After polymerization or in polymerized form, the monomers m1 are each covalently bonded via the carbon atom which carries the groups R ¹ and R ² , and via the carbon atom which carries the groups R ³ and R ⁴ , with further monomers. Accordingly, after polymerization or in polymerized form, the monomers m2 are each covalently bonded via the carbon atom which carries the group R ⁵ and via the carbon atom which carries the groups R ⁶ and R ⁷ with other monomers.

A molar ratio of the monomers m1 used to the monomers m.sup.2 used is advantageously in the range from 0.5 to 6, in particular 0.7 to 4, preferably 0.9 to 3.8, more preferably 1 .0 to 3.7 or 2 to 3.5.

In particular, R ¹ = COOM, R ² = H or CH ₃ , R ³ = R ⁴ = H Thus, the copolymer can be prepared on the basis of acrylic or methacrylic acid monomers, which is interesting from an economic point of view. In addition, such copolymers have a particularly good dispersing effect in the present context.

Also advantageous may be monomers with R ¹ = COOM, R ² = H, R ³ = H and R ⁴ = COOM. Corresponding copolymers can be prepared on the basis of maleic acid monomers. The group X of the ionizable monomers m2 is advantageously at least 75 mol%, in particular at least 90 mol%, especially at least 95 mol% or at least 99 mol% of all monomers m2 for -O- (= oxygen atom).

Advantageously, R ⁵ = H or CH ₃ , R ⁶ = R ⁷ = H and X = -O-. Thus, the copolymers can be prepared, for example, starting from (meth) acrylic acid esters, vinyl, (meth) allyl or isoprenol ethers.

In a particularly advantageous embodiment, R ² and R ^{5 are} each mixtures of 40-60 mol% H and 40-60 mol% CH 3.

According to a further advantageous embodiment, R ¹ = COOM, R ² = H, R ⁵ = -CH ³ and R ³ = R ⁴ = R ⁶ = R ⁷ = H. In another advantageous embodiment, R ¹ = COOM, R ² = R ⁵ = H or -CH ₃ and R ³ = R ⁴ = R ⁶ = R ⁷ = H.

Particularly preferred are R ⁵ = CH ₃ , R ⁶ = R ⁷ = H, X = -O-, p = 1 and m = 0. Thus, copolymers can be prepared with methacrylic ester-based side chains, which has proved to be particularly advantageous in the present case ,

Especially suitable are monomers in which R ¹ = COOM; R ² and R ⁵ each independently represent H, -CH 3 or mixtures thereof; R ³ and R ^{6 are} each independently H or -CH 3, preferably H; R ⁴ and R ^{7 are} each independently H or -COOM, preferably H.

The radical R ⁸ in the side chain-carrying monomers m2, based on all radicals R ^{8 of} the monomers, in particular to at least 50 mol%, in particular at least 75 mol%, preferably at least 95 mol% or at least 99 mol%, from a polyethylene oxide. A proportion of ethylene oxide units based on all alkylene oxide units in the copolymer is in particular more than 75 mol%, in particular more than 90 mol%, preferably more than 95 mol% and in particular 100 mol%.

In particular, R ^{8 has} substantially no hydrophobic groups, in particular no alkylene oxides having three or more carbon atoms. This means in particular that a proportion of alkylene oxides having three or more carbon atoms, based on all alkylene oxides, is less than 5 mol%, in particular less than 2 mol%, preferably less than 1 mol% or less than 0.1 mol%. In particular, there are no alkylene oxides having three or more carbon atoms or their proportion is 0 mol%. R ^a is advantageously H and / or a methyl group. Particularly advantageous is A = C2-alkylene and R ^a is H or a methyl group.

In particular, the parameter n = 10-150, in particular n = 15-100, preferably n = 17-70, in particular n = 19-45 or n = 20-25. In particular in the preferred ranges mentioned, this leads to excellent dispersing effects achieved. Particularly preferably, R ^{1 is} COOM; R ² and R ⁵ , independently of one another, are H, -CH 3 or mixtures thereof; R ³ and R ⁶ , independently of one another, are H or -CH 3, preferably H; R ⁴ and R ⁷ , independently of one another, are H or -COOM, preferably H; and wherein X is at least 75 mole%, especially at least 90 mole%, especially at least 99 mole% of all monomers m2 is -O-.

According to a further advantageous embodiment, at least one further monomer ms is present during the polymerization, which is polymerized, in particular a monomer of the formula III:

wherein R ^{5 '} , R ^6' , R ^{7 '} , m' and p 'such as R ⁵ , R ⁶ , R ⁷ , m and p are as defined above;

Y, each independently, is a chemical bond or -O-;

Z, each independently, is a chemical bond, -O- or -NH-;

R ⁹ , in each case independently of one another, represents an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or an acetoxyalkyl group, each having 1 to 20 C atoms.

After polymerization or in polymerized form, the monomers are in each case via the carbon atom which carries the group R ^{5 '} , and via the carbon atom, which carries the groups R ^{6 '} and R ^7' , covalently bonded to other monomers.

For example, further monomers ms are advantageous where m '= 0, p' = 0, Z and Y represent a chemical bond and R ^{9 is} an alkylaryl group having 6 - 10 C atoms.

Also particularly suitable are other monomers ms in which m '= 0, p' = 1, Y is -O-, Z represents a chemical bond and R ^{9 is} an alkyl group having 1-4 C-atoms.

Furthermore, further monomers ms are suitable where m '= 0, p' = 1, Y is a chemical bond, Z is -O- and R ^{9 is} an alkyl group and / or a hydroxyalkyl group having 1-6 C atoms ,

When m '= 0, p' = 1, Y is a chemical bond, Z is -O-, preferably R ^{5 '} = R ^6' = R ^{7 '} = H. Thus, the further monomer ms may be present Base of an acrylate ester, which is particularly advantageous. The further monomer ms is particularly advantageously vinyl acetate, styrene and / or hydroxyalkyl (meth) acrylate, in particular a hydroxyalkyl acrylate, very particularly a hydroxyethyl acrylate.

The solution polymerization according to the invention is carried out in particular in a polar solvent, preferably in an aqueous solvent, more preferably in water. It is therefore possible to dispense with environmentally problematic solvents. Surprisingly, however, the polymerization reactions still proceed efficiently and controllably.

In particular, the polar solvent has a relative permittivity ε _Γ > 5, preferably> 20, in particular> 50, more preferably> 70, the permittivity being measured in particular at a temperature of 25 ° C. to a pressure of 1 bar. The relative permittivity He we also referred to as the dielectric constant and represents the ratio of permittivity ε to the permittivity εο of the vacuum. Such solvents have been found to be particularly suitable in the present case. Most preferably, the solvent contains or consists of water and / or alcohol. Especially preferably, the solution contains or consists of medium from water. Suitable alcohols are, for example, methanol, ethanol, propanol, butanol, diethylene glycol and / or triethylene glycol.

Especially preferably, the solution polymerization takes place in a homogeneous phase. In other words, this means that preferably no disperse phases are present.

With particular preference the monomers to be polymerized, based on the total weight of monomers and solvent to be polymerized, have a weight fraction of 25-75% by weight, in particular 30-50% by weight, in particular 35-45% by weight , According to a particularly preferred embodiment, the agent is a carboxy group-bearing β-phosphonitroxide. In particular, this is a compound of the formula X:

wherein R ^{11 is} a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 3 to 4, carbon atoms;

R ¹² and R ¹³ , each independently of one another, are hydrogen or a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 3 to 4, carbon atoms; R ¹⁴ and R ¹⁵ , each independently of one another, are a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 2 to 3, carbon atoms;

R ¹⁶ and R ¹⁷ , each independently of one another, are a linear or branched alkyl radical having 1 to 6, in particular 1 to 4, preferably 1 to 2, carbon atoms; T, independently of one another, represents H ⁺ , an alkali metal ion, an alkaline earth metal ion, a divalent or trivalent metal ion, an ammonium ion or an organic ammonium group.

Very particular preference is given to compounds in which: i) R ¹¹ and R ^{13 are} each an alkyl group having 4 carbon atoms, in particular a tert-butyl group; ii) R ^{12 is} hydrogen; iii) R ¹⁴ and R ^{15 are} each an alkyl group having 2 carbon atoms, especially an ethyl group; iv) R ¹⁶ and R ¹⁷ each represent an alkyl group having 1 carbon atom, in particular a methyl group; and v) T represents an alkali metal ion, in particular a Li and / or Na ion.

In particular, the agent has a ratio of carboxy groups to nitroxide groups of 2: 1-1: 2, preferably 1: 1. Most preferably, the agent has exactly one carboxy group and exactly one nitroxide group.

Such agents have proven to be optimal in order to ensure an efficient production process and to obtain a defined structure of the copolymers or dispersants.

A molar ratio of agent to the total molar amount of the monomers to be polymerized is in particular 1:10 to 1: 100, preferably 1:20 to 1:90, in particular 1: 25 to 1:75, very particular 1:30 to 1:70.

The nitroxide-mediated solution polymerization is advantageously carried out at a pH in the range of 3 to 13, in particular 4 to 12 or 6 to 11, in particular 7 to 10, in very particular 7.5 to 10 or 7.5 to 8.5. If a block copolymer is prepared, blocks comprising side-chain-carrying monomers m2 are polymerized according to an advantageous embodiment at a pH of 6 to 13, in particular 7 to 12, particularly preferably 8 to 11. Blocks containing ionizable monomers m1 are preferably polymerized at a pH of 3-7, in particular 4-6. In the preparation of a copolymer with random (= random) monomer distribution and / or a copolymer with a gradient structure, the polymerization in an advantageous embodiment takes place in the range from 5 to 9, in particular 6 to 8 or 6.5 to 7.5. In a further particular embodiment, the polymerization takes place at a pH greater than 7, in particular at a pH of 7.5-13, in particular 8-12, in particular 8-10, preferably 9-1.1. This is especially independent of the structure of the copolymers.

The polymerization preferably takes place at a pH of less than 1 l, in particular at a pH greater than 7 and less than 1 l, particularly preferably at a pH of 7.5-10, in particular at a pH of 7.5-9 or 7.5-8.5. This is especially independent of the structure of the copolymers.

According to a particularly preferred embodiment, the nitroxide-mediated solution polymerization takes place in the presence of a base, preferably in the presence of an alkali metal hydroxide and / or an alkali metal bicarbonate, in particular in the presence of sodium hydroxide and / or sodium bicarbonate. As a result, a particularly uniform distribution of the agent in the reaction mixture is achieved, which benefits the overall efficiency of the process. In addition, the pH of the reaction mixture can be increased by the addition of the base, which has proved to be additionally advantageous in the present case.

Most preferably, the agent is at least partially premixed with the base. This especially at room temperature or 25 ° C.

The molar ratio of base to agent is in particular 1: 1 to 10: 1, preferably 2: 1 to 5: 1.

Preferably, the at least partially premixed agent is then added to the monomers to be polymerized and any solvent. Preferably, the monomers to be polymerized and any solvent are already present at the temperature at which the polymerization reaction takes place. In particular, the nitroxide-mediated solution polymerization takes place at a temperature of 40-120 ° C., in particular 60-1 10 ° C., preferably 70-100 ° C. Such temperatures allow a rapid and easily controllable reaction of the monomers. In principle, it is also possible to work in other temperature ranges.

In particular, a copolymer having a polydispersity (= weight-average molecular weight Mw / number-average molecular weight M _n ) of the copolymer is ≦ 1.5, in particular in the range of 0.1-0.1, especially 1.2-1.3 , produced.

A weight-average molecular weight Mw of the entire copolymer is in particular in the range of 10Ό00 - 150Ό00 g / mol, advantageously 12Ό00 - 80Ό00 g / mol, especially 12Ό00 - 50Ό00 g / mol. In the present context, molecular weights such as weight average molecular weight Mw or number average molecular weight Mn are determined by gel permeation chromatography (GPC) with polyethylene glycol (PEG) as a standard. This technique is known per se to the person skilled in the art.

In particular, during the polymerization, a molar ratio of free ionizable monomers m1 to free sidechain-bearing monomers m2 is changed at least temporarily.

Specifically, the change in the molar ratio includes stepwise and / or continuous change. In this way, a block structure and / or a concentration gradient or a gradient structure can be formed in a manner which is easy to control. Optionally, during the polymerization both a continuous change and a stepwise change in the molar ratio of the free ionizable monomers m1 to the free side chain-carrying monomers m2 occurs. This stepwise change takes place in particular in time before the continuous change is carried out. As a result, for example, a copolymer comprising two or more sections of different structure are available. To form copolymers with block and / or gradient structures, the ionizable monomers m1 and the side chain-carrying monomers m2 are preferably added at least partially offset in time.

According to a further preferred embodiment, during the polymerization in a first step a) a portion of the ionizable monomers m1 are reacted or polymerized and after reaching a predetermined conversion in a second step b) the unreacted ionizable monomers m1 together with the side chain bearing monomers m2 polymerized. Step a) takes place, in particular, essentially in the absence of side chain-carrying monomers m2.

As a result, a copolymer having a section which consists essentially of polymerized ionizable monomers m1 and a subsequent section having a gradient structure can be produced in a simple and cost-effective manner. According to a very particularly preferred embodiment, in the polymerization in a first step a) a part of the side chain-carrying monomers m2 reacted or polymerized and after reaching a predetermined conversion in a second step b) the unreacted side chain-bearing monomers m2 together with the ionizable monomers m1 polymerized. Step a) is carried out in particular substantially in the absence of ionizable monomers m1.

Thereby, e.g. in a simple and cost-effective manner, a copolymer having a section which consists essentially of polymerized side-chain-carrying monomer monomers m2 and a subsequent section with gradient structure can be produced.

It is advantageous to carry out steps a) and b) directly following one another. As a result, the polymerization reaction in steps a) and b) can be maintained as best as possible.

The polymerization in step a) is carried out in particular until 0.1 to 100 mol%, in particular 1 to 95 mol%, preferably 10 to 90 mol%, im Specific 25-85 mole percent of the ionizable monomers m1 or side chain bearing monomers m2 are reacted or polymerized.

The conversion of the monomers m1 and m2 or the progress of the polymerization can e.g. be controlled by means of liquid chromatography, in particular high-performance liquid chromatography (HPLC), in a conventional manner.

In particular, the copolymer is at least 50 mole%, especially at least 75 mole%, especially at least 90 mole% or 95 mole%, of ionizable monomers m1 and side chain bearing monomers m2. The copolymer can be prepared in liquid or solid form. The copolymer is particularly preferably present as a constituent of a solution or dispersion, with a proportion of the copolymer being in particular 10 to 90% by weight, preferably 25 to 65% by weight. As a result, for example, the copolymer can be added very well to binder compositions. If the copolymer is prepared in solution, in particular in aqueous solution, it is also possible to dispense with further preparation.

According to another advantageous embodiment, a copolymer is prepared in a solid state, in particular in the form of a powder, in the form of pellets and / or plates. This simplifies in particular the transport of the coplymers. Solutions or dispersions of the copolymers may e.g. be converted by spray drying in the solid state.

Depending on the reaction procedure, polymers of predetermined or well-defined structure can be prepared in a controlled manner with the process according to the invention. In particular, e.g. Random (= random) monomer distribution copolymers, block structure copolymers, and / or gradient structure copolymers are available.

In particular, the copolymer is a polymer of substantially linear structure. This means in particular that all monomer units of the copolymer are arranged in a single and / or unbranched polymer chain. In particular, the copolymer does not have a star-shaped structure and / or the copolymer is not part of a branched polymer. In particular, the copolymer is not part of a polymer in which a plurality of, in particular three or more, extending in different directions polymer chains are attached to a central molecule.

Copolymers with random monomer distribution

For example, it is possible to polymerize the ionizable monomers m1 and the side chain-carrying monomers m2 such that a random or random monomer distribution is formed in the copolymer. For the preparation of a copolymer having a statistical monomer distribution, a mixture of ionizable monomers m1 and side chain-carrying monomers m2 is preferably prepared and these are reacted together to form the copolymer by the nitroxide-mediated solution polymerization according to the invention. The reaction may e.g. are terminated when the conversion of the monomers> 90 mol%.

Copolymers with block structure

According to another advantageous embodiment, the ionizable monomers m1 and the side-chain-carrying monomers m2 are converted into a block-structured copolymer, the side-chain-carrying monomers m2 substantially in at least one first block A and ionizable monomers m1 substantially in at least one second block B, to be installed.

In this case, a possibly present proportion of monomers m1 in the first block A is advantageously less than 25 mol%, in particular less than or equal to 10 mol%, based on all monomers m2 in the first block A. In addition, a possibly present proportion of monomers m2 is second block B is in particular less than 25 mol%, in particular less than or equal to 10 mol%, based on all the monomers m1 in the second block B. The following procedure has proven to be particularly preferred for the preparation of copolymers comprising a block structure: In a first step a) at least a portion of the side chain-carrying monomers m2 are reacted or polymerized and after reaching a predetermined conversion in a second step b) the ionizable monomers m1, optionally together with possibly not yet reacted side chain-bearing monomers m2, polymerized. Step a) takes place in particular in the absence of ionizable monomers m1.

The polymerization in step a) is carried out in particular until 75-95 mol%, preferably 85-95 mol%, in particular 86-92 mol%, of the initially charged monomers m2 have been reacted or polymerized.

In particular, the polymerization in step b) is carried out correspondingly until 75 to 95 mol%, in particular 80 to 92 mol%, of the originally introduced monomers m1 are reacted or polymerized. The sequence of steps a) and b) can, however, in principle also be exchanged.

As has been shown, it is advantageous to react the monomers m1 or m2 in steps a) and b) up to the above-mentioned conversions. In addition, it is advantageous to carry out steps a) and b) directly one after the other regardless of the selected sequence. As a result, the polymerization reaction in steps a) and b) can be maintained as best as possible.

The process can be carried out, for example, by introducing monomers m2 in a solvent, for example water, in step a) and then polymerizing to form a first block A. As soon as the desired conversion of monomer m2 has been reached (for example 75-95 mol%, in particular 80-92 mol%, see above), monomers m1 are added without any delay in step b) and the polymerization is continued. In this case, the monomers m1 are added in particular to the already formed block A, whereby a second block B is formed. The polymerization is advantageously continued until the desired conversion of monomer m1 (eg 75-95 Mole%, especially 80-92 mole%; see above). As a result, for example, a diblock copolymer comprising a first block A and a second block B connected thereto is obtained.

In principle, however, it is also possible in the first step to first convert the ionizable monomers m1 and only in the second step b) the side chain-carrying monomers m2 in an analogous manner.

The monomers m2 and any further monomers are present in the first block A of the copolymer, in particular randomly or randomly distributed. Likewise, the monomers m1 and any further monomers are present in the second block B of the copolymer, in particular randomly or randomly.

In other words, the at least one block A and / or the at least one block B is preferably present in each case as a partial polymer with random monomer distribution.

The at least one first block A advantageously comprises 5 to 70, in particular 7 to 40, preferably 10 to 25, monomers m2 and / or the at least one second block B comprises 5 to 70, in particular 7 to 50, preferably 20. 40, monomers m1.

A possibly present proportion of monomers m1 in the first block A is preferably less than 15 mol%, in particular less than 10 mol%, especially less than 5 mol% or less than 1 mol%, based on all monomers m2 in the first block A. In addition, a possibly existing proportion of monomers m2 in the second block B is advantageously less than 15 mol%, in particular less than 10 mol%, especially less than 5 mol% or less than 1 mol%, based on all monomers m1 in the second block B. Advantageously, both conditions are met at the same time.

Thus, the monomers m1 and m2 are substantially spatially separated, which benefits the dispersing effect of the copolymer and is advantageous in view of the delay problem.

The first block A is based on all monomers in the first block A in particular at least 20 mol%, in particular at least 50 mol%, especially at least 75 mol% or at least 90 mol% of monomers m2 of the formula II. The second block B is based on all monomers in the second block B advantageously at least 20 mol%, in particular at least 50 mol%, especially at least 75 mol% or at least 90 mol% of monomers m1 of the formula I. According to a further advantageous embodiment, at least one further polymerizable monomer ms is present in step a) and / or in step b). The at least one further polymerizable monomer ms is polymerized in this case, in particular together with the monomer m1 and / or the monomer m2. However, it is also possible, in addition to step a) and step b), to provide a further step c) of the polymerization of the at least one further polymerizable monomer ms. Thereby, a copolymer with an additional block C can be produced. In particular, step c) is performed temporally between step a) and step b). In this way, the additional block C is arranged spatially between the blocks A and B.

If present in the first block A, the at least one further monomer ms in the first block A advantageously has a proportion of 0.001-80 mol%, preferably 20-75 mol%, especially 30-70 mol%, based on all monomers in the first block A, up. If present in the second block B, the at least one further monomer ms in the second block B has in particular a proportion of 0.001-80 mol%, preferably 20-75 mol%, especially 30-70 mol% or 50-70 mol% , based on all monomers in the second block B, on.

According to an advantageous embodiment, in the first block A and / or in the second block B, the at least one further monomer ms having a proportion of 20-75 mol%, especially 30-70 mol%, based on all monomers in the respective block , available.

A particularly advantageous copolymer having a block structure has at least one or more of the following features: (i) Block A has 7 to 40, in particular 10 to 25, monomers m2 and block B has 7 to 50, in particular 20 to 40, monomers m1 , (ii) The first block A is based on all monomers in the first block A to at least 75 mol%, preferably at least 90 mol%, of monomers m2 of the formula II;

(iii) Based on all the monomers in the second block B, the second block B comprises at least 75 mol%, preferably at least 90 mol%, of monomers m1 of the formula I;

(iv) A molar ratio of the monomers m1 to the monomers m2 in the copolymer is in the range from 0.5 to 6, preferably 0.8 to 3.5;

(v) R ¹ is COOM; (vi) R ² and R ⁵ are H or CH 3, preferably CH 3;

(vii) R ³ = R ⁴ = R ⁶ = R ⁷ = H;

(viii) m = 0 and p = 1;

(ix) X = -O-

(x) A = C 2 -alkylene and n = 10-150, preferably 15-50; (xi) R ^a = H or -CH ₃ , preferably CH ₃ ;

Especially preferred is a diblock copolymer, consisting of blocks A and B, which has at least all features (i) - (iv). Further preferred is a diblock copolymer which has all the features (i) - (xi). Even more preferred is a diblock copolymer which realizes all features (i) - (xi) in the respectively preferred embodiments.

Also advantageous is a triblock copolymer consisting of the blocks A, B and C, in particular in the sequence ACB, wherein the triblock copolymer at least all features (i) - (iv). Further preferred is a triblock copolymer which has all the features (i) - (xi). Even more preferred is a triblock copolymer which realizes all the features (i) - (xi) in the respectively preferred embodiments. Block C advantageously comprises monomer ms as described above or block C consists thereof. In a specific embodiment, in these diblock copolymers or triblock copolymers, additionally in block A and B there is additionally contained a further monomer ms as described above.

Gradient-Structure Copolymers According to another advantageous embodiment, the ionizable monomers m1 and the side-chain-carrying monomers m2 are polymerized together at least in a portion of the copolymer to form a concentration gradient and / or a gradient structure.

The term "gradient structure" or "concentration gradient" herein means, in particular, a continuous change in the local concentration of a monomer in at least one portion in a direction along the backbone of the copolymer. Another term for "concentration gradient" is "concentration gradient".

The concentration gradient may e.g. be essentially constant. This corresponds to a linear decrease or increase in the local concentration of the respective monomers in at least a portion along the direction of the backbone of the copolymer. However, it is possible that the concentration gradient changes along the direction of the backbone of the copolymer. In this case, there is a nonlinear decrease or increase in the local concentration of the respective monomers. The concentration gradient extends in particular over at least 10, in particular at least 14, preferably at least 20 or at least 40, monomers of the copolymer.

In contrast, abrupt changes in the concentration of monomers, e.g. occur in block copolymers, not referred to as concentration gradient.

The term "local concentration" as used herein refers to the concentration of a particular monomer at a given site of the polymer backbone. In practice, the local concentration or the mean value of the local concentration can be determined, for example, by determining the monomer conversions during the production of the copolymer. In this case, the monomers reacted in a certain period can be determined become. In this case, the average local concentration corresponds in particular to the ratio of the molar fraction of a specific monomer converted in the period considered to the total molar amount of monomers reacted in the period under consideration. The conversions of the monomers can be determined, for example, by means of liquid chromatography, in particular high-performance liquid chromatography (HPLC), and taking into account the amounts of monomers used, in a manner known per se.

The copolymer produced may also have more than one segment with a gradient structure, in particular two, three, four or even more segments, which may be e.g. arranged one behind the other. If present, different gradient structures or concentration gradients may exist in each of the different sections.

Preferably, in the at least one portion having a gradient structure, a local concentration of the at least one ionizable monomer m1 continuously increases along the polymer backbone while a local concentration of the at least one sidechain-carrying monomer m2 continuously decreases along the polymer backbone or vice versa.

Specifically, a local concentration of the ionizable monomer m1 at the first end of the at least one gradient structure portion is less than at the second end of the gradient structure portion, while a local concentration of side chain bearing monomer m2 at the first end of the gradient structure portion is greater than at second end of the section with gradient structure, or vice versa. In particular, when dividing the at least one gradient structure section into 10 equally long subsections, the average local concentration of the at least one ionizable monomer m1 in the respective subsections along the polymer backbone is at least 3, in particular at least 5 or 8, successive subsections As the average local concentration of the at least one side-chain-bearing monomer m2 in the respective subsections increases of the polymer backbone decreases in at least 3, in particular in at least 5 or 8, successive subsections, or vice versa.

Specifically, an increase or decrease in the averaged local concentration of the at least one ionizable monomer m1 in the successive subsections is substantially constant while, advantageously, a decrease or increase in the averaged local concentration of the at least one sidechain bearing monomer unit m2 in the successive Subsections is also essentially constant.

In a first step a), at least part of the side-chain-carrying monomers m2 are reacted or polymerized and after reaching a predetermined conversion in a second step b) the ionizable monomers m1 together with unreacted side chain-carrying monomers m2, polymerized. Step a) takes place in particular in the absence of ionizable monomers m1.

It is also possible in a first step a) to react or polymerize at least a portion of the ionizable monomers m1 and after reaching a predetermined conversion in a second step b) the side chain-bearing monomers m2, optionally together with possibly not yet reacted ionizable monomers m1, to polymerize. Step a) takes place in particular in the absence of ionizable monomers m2.

In particular, according to the former process, copolymers having a gate consisting essentially of polymerized side-chain-carrying monomer monomers m2 and having a subsequent gradient-type section can be prepared in an efficient and cost-effective manner.

In this case, the polymerization in step a) is carried out in particular until 1-74 mol%, preferably 10-70 mol%, in particular 25-70 mol%, especially 28-50 mol% or 30-45 mol% % of the side chain carrying mono- m2 or the ionizable monomers m1 are reacted or polymerized.

According to a further advantageous embodiment, at least one further polymerisable monomer ms of the formula III is present in step a) and / or in step b). The at least one further polymerizable monomer ms is polymerized in this case, in particular together with the monomer m1 and / or the monomer m2.

According to an advantageous embodiment, the at least one section with the gradient structure, based on a total length of the polymer backbone, has a length of at least 30%, in particular at least 50%, preferably at least 75% or 90%.

Advantageously, the at least one section with the gradient structure, based on a total number of monomers in the polymer backbone, has a proportion of at least 30%, in particular at least 50%, preferably at least 75% or 90%, of monomers.

In particular, the at least one section having a gradient structure, based on the weight-average molecular weight of the entire copolymer, has a weight fraction of at least 30%, in particular at least 50%, preferably at least 75% or 90%. Thus, the section with gradient structure with the concentration gradient or the gradient structure in particular mass comes into play.

The at least one section having a gradient structure advantageously comprises at least 5, in particular at least 7, preferably at least 10 monomer units m1 and / or at least 5, in particular at least 7, preferably at least 10, monomer units m2.

The at least one section with gradient structure advantageously comprises at least 5, in particular at least 7, preferably at least 10 monomer units m1 and at least 5, in particular at least 7, preferably at least 10, monomer units m2. The at least one section having a gradient structure advantageously comprises 5 to 70, in particular 7 to 40, preferably 10 to 25 monomers m1 and 5 to 70, in particular 7 to 40, preferably 10 to 25, monomers m2.

It is advantageous if at least 30 mol%, in particular at least 50 mol%, preferably at least 75 mol%, in particular at least 90 mol% or at least 95 mol%, of the ionizable monomers m1 in at least one section which a Gradient structure, are present.

Also advantageously at least 30 mol%, in particular at least 50 mol%, preferably at least 75 mol%, in particular at least 90 mol% or at least 95 mol%, of the side chain-carrying monomers m2 in the at least one section, which is a Gradient structure, are present.

Especially preferably, the last two aforementioned conditions apply simultaneously.

In another advantageous embodiment, the copolymer additionally lent to at least one section which has a gradient structure, over a further section, wherein over the entire section substantially a constant local concentration of the monomers and / or a random or random distribution of the monomers is present , This section may e.g. consist of monomers of a single variety or of several different monomers, which are randomly distributed. In particular, however, there is no gradient structure or concentration gradient along the polymer backbone in this section.

The copolymer may also have more than one other portion, e.g. two, three, four or even more sections, which may differ chemically and / or structurally.

The section with the gradient structure preferably directly adjoins the further section with the statistical monomer distribution.

It has surprisingly been found that such copolymers may be even more advantageous over time with respect to the liquefaction effect and maintenance thereof. In particular, the further statistical distribution section comprises ionizable monomers m1 and / or side-chain-carrying monomers m2.

With regard to all the monomers contained therein, the further section with the random monomer distribution in one embodiment of the invention comprises e.g. advantageously at least 30 mol%, in particular at least 50 mol%, preferably at least 75 mol%, in particular at least 90 mol% or at least 95 mol%, of ionizable monomers m1. A possibly existing proportion of side-chain-carrying monomers m2 in the further section with random monomer distribution is in particular less than 25 mol%, especially less than 10 mol% or less than 5 mol%, based on all monomers m1 in the further section , In particular, no side chain-bearing monomers m2 are present in the further statistical monomer distribution section.

According to a further and particularly advantageous implementation of the invention, the further section with statistical monomer distribution, based on all monomers contained therein, at least 30 mol%, especially at least 50 mol%, preferably at least 75 mol% in particular at least 90 mol. % or at least 95 mole% side chain-bearing monomers m2. In this case, a possibly present proportion of ionizable monomers m1 in the further section is in particular less than 25 mol%, in particular less than 10 mol% or less than 5 mol%, based on all monomers m2 in the further section with statistical monomer distribution. In particular, no ionizable monomers m1 are present in the further section with statistical monomer distribution. It has proven to be expedient that the further section comprises a total of 5 to 70, in particular 7 to 40, preferably 10 to 25 monomers. These are in particular monomers m1 and / or m2.

A ratio of the number of monomer units in the at least one section having a gradient structure to the number of monomers in the at least one further section having a statistical monomer distribution is advantageously in the range from 99: 1 to 1:99, in particular 10:90 to 90:10, preferably 80:20. 20:80, especially 70:30 - 30:70. A particularly advantageous gradient-structure copolymer has at least one or more of the following features:

(i) The copolymer is at least 75 mole%, especially at least 90 mole% or 95 mole%, of ionizable monomers m1 and side chain carrying monomers m2;

(ii) the copolymer comprises or consists of the at least one gradient structure section and another monomer distribution section;

(iii) The further section with random monomer distribution comprises side chain-carrying monomers m2, in particular at least 50 mol%, preferably at least 75 mol%, in particular at least 90 mol% or at least 95 mol%, based on all of additional monomeric monomer distribution section. A possibly present proportion of ionizable monomers m1 in the further section is less than 25 mol%, in particular less than 10 mol% or less than 5 mol%, based on all monomers m2 in the further section with statistical monomer distribution.

(iv) A molar ratio of the monomers m1 to the monomers m2 in the copolymer is in the range of 0.5-6, preferably 0.8-3.5; (v) R ¹ is COOM;

(vi) R ² and R ⁵ are H or Chta, preferably Chta;

(vii) R ³ = R ⁴ = R ⁶ = R ⁷ = H;

(viii) m = 0 and p = 1;

(ix) X = -O- (x) A = C 2 -alkylene and n = 10-150, preferably 15-50; (xi) R ^a = H or -CH ₃ , preferably CH ₃ ;

Especially preferred is a copoly-mer consisting of a gradient structure section and a random monomer distribution section having at least all features (i) - (iv). Further preferred a copolymer which has all the features (i) - (xi). Even more preferred is a copolymer which realizes all features (i) - (xi) in the respectively preferred embodiments.

Use of the Copolymers Further, the present invention relates to the use of a copolymer as described above as a dispersant for solid particles.

The term "solid particles" stands for particles of inorganic and / or organic materials. In particular, it is inorganic and / or mineral particles. The copolymer is particularly advantageously used as a dispersant for mineral binder compositions. The copolymer can be used in particular for liquefaction, for water reduction and / or for improving the processability of a mineral binder composition. In particular, the copolymer can be used to extend the processability of a mineral binder composition.

Further, the present invention further relates to a mineral binder composition containing at least one copolymer as described above. The mineral binder composition contains at least one mineral binder. By the term "mineral binder" is meant in particular a binder which reacts in the presence of water in a hydration reaction to solid hydrates or hydrate phases. This may be, for example, a hydraulic binder (e.g., cement or hydrated lime), a latent hydraulic binder (e.g., slag), a pozzolanic binder (e.g., fly ash), or a nonhydraulic binder (gypsum or lime).

In particular, the mineral binder or binder composition contains a hydraulic binder, preferably cement. Particularly preferred is a cement having a cement clinker content of> 35 wt .-%. In particular, the cement is of the type CEM I, CEM II, CEM III, CEM IV or CEM V (according to standard EN 197-1). A proportion of the hydraulic binder in the total mineral binder is advantageously at least 5 wt .-%, in particular at least 20 wt .-%, preferably at least 35 wt .-%, in particular at least 65 wt .-%. According to a further advantageous embodiment, the mineral binder consists of> 95% by weight of hydraulic binder, in particular of cement or cement clinker.

However, it may also be advantageous if the mineral binder or the mineral binder composition contains or consists of other binders. These are in particular latent hydraulic binders and / or pozzolanic binders. Suitable latent hydraulic and / or pozzolanic binders are e.g. Slag, fly ash and / or silica fume. Likewise, the binder composition may include inert substances such as e.g. Limestone, quartz flour and / or pigments. In an advantageous embodiment, the mineral binder contains 5 to 95% by weight, in particular 5 to 65% by weight, particularly preferably 15 to 35% by weight, of latently hydraulic and / or pozzolanic binders. Advantageous latent hydraulic and / or pozzolanic binders are slag and / or fly ash.

In a particularly preferred embodiment, the mineral binder contains a hydraulic binder, in particular cement or cement clinker, and a latent hydraulic and / or pozzolanic binder, preferably slag and / or fly ash. The proportion of latent hydraulic and / or pozzolanic binder is particularly preferably 5 to 65 wt .-%, particularly preferably 15 to 35 wt .-%, while at least 35 wt .-%, in particular at least 65 wt .-%, of the hydraulic Binder present.

The mineral binder composition is preferably a mortar or concrete composition.

The mineral binder composition is, in particular, a processable and / or water-mixed mineral binder composition. A weight ratio of water to binder in the mineral binder composition is preferably in the range from 0.25 to 0.7, in particular 0.26 to 0.65, preferably 0.27 to 0.60, in particular 0.28 to 0.55.

The copolymer is advantageously used in a proportion of 0.01-10% by weight, in particular 0.1-7% by weight or 0.2-5% by weight, based on the binder content. The proportion of the copolymer refers to the copolymer itself. In the case of a copolymer in the form of a solution, the solids content is correspondingly decisive.

An additional aspect of the present invention relates to a molded article, in particular a component of a building, obtainable by curing a mineral binder composition as described above comprising a copolymer after the addition of water. A building can e.g. a bridge, a building, a tunnel, a lane, or a runway. From the following embodiments, further advantageous embodiments of the invention result.

embodiments

1 . Preparation Examples for Polymers 1 .1 Statistical Polymer R1 For comparison purposes, a polymer R1 with random or random monomer distribution was prepared. Polymer R1 was prepared by polymer-analogous esterification (PAE). In this case, the procedure was essentially as described in EP 1 138 697 B1 on page 7, line 20 to page 8, line 50, as well as in the examples mentioned therein. Specifically, a poly (methacrylic acid) was esterified with methoxy-polyethylene glycol (mono-methoxy-terminated polyethylene glycol having an average molecular weight of 1 × 100 g / mol, -20 ethylene oxide units / molecule) to give a molar ratio of methacylic acid units to ester groups equal to 2 (m1 / m2 = 2). The solids content of the polymer R1 is about 40 wt .-%. 1 .2 diblock copolymer P1

To prepare a diblock copolymer P1 by means of nitroxide-mediated solution polymerization, in a round bottom flask equipped with a reflux condenser, stirrer, thermometer and an inert gas inlet tube, 1 .6 g of 50% methoxy-polyethylene glycol homo-methacrylate (average molecular weight: 1 × 100 g / mol; -20 ethylene oxide units / molecule) 53.2 mg of styrene and 5 g of deionized water submitted. The reaction mixture was heated to 90 ° C with vigorous stirring. A slight stream of inert gas (N2) was passed through the solution during the warm-up and the entire remaining reaction time.

Thereafter, a solution of 10 g of 0.1 N sodium bicarbonate and 85 mg of "BlocBuilder MA" (Agens, CAS No.: 654636-62-1, available from Arkema, France) was added. Now, the conversion of the methoxy-Polyethylenglykohooo-methacrylate was monitored by HPLC. As soon as it was over 85%, 1 .0 g of methacrylic acid was added. As soon as the conversion of the methacrylic acid exceeded 80%, the reaction was stopped.

The molar ratio of methacrylic acid units to methoxy-polyethylene glycol methacrylate was 2 (m1 / m2 = 2) and the solids content of polymer P1 was about 40% by weight. 1 .3 Statistical polymer P2

A second polymer P2 with random or random monomer distribution was produced. In this case, the procedure was analogous to the preparation of polymer P1 (previous chapter), but the methacrylic acid initially presented together with the methoxy-Polyethylenglykohooo-methacrylate. The solids content of the polymer P2 was again about 40 wt .-%.

1 .4 Statistical polymer P3

A third polymer P3 with random or random monomer distribution was prepared. This procedure was analogous to the preparation of polymer P2 (Chapter 1 .3), wherein a mixture of methacrylic acid, methoxy-Polyethylenglykohooo-methacrylate and 2-hydroxy-ethyl-acrylate (HEA, as another monomer ms) at a temperature of 80 ° C. was presented together. The solution polymerization was then carried out at a pH of 8. This was adjusted by the added amount of base in the solution containing BlocBuilder MA. The conversion of the monomers increased substantially linearly over a period of about 50 minutes. Accordingly, the reaction can be well controlled.

The molar ratio of methacrylic acid units: methoxy-polyethylene glycol methacrylate: 2-hydroxyethyl acrylate was 4: 2: 1 and the solids content of the polymer P3 about 40 wt .-%. The polymers P3 have also been found to be stable. In particular, no appreciable hydrolysis of the acrylate or methacrylate monomers could be detected during and after the preparation of the polymers in the HPLC measurements.

1 .5 Statistical polymer P4

A fourth polymer P4 with random or random monomer distribution was prepared. The procedure was as in the preparation of polymer P3 (Chapter 1 .4) (temperature also 80 ° C), instead of the pH of 8 but adjusted to a pH of 4 by the addition of a base was omitted. In this case, in contrast to the preparation of the polymer P3 initially no solution but a heterogeneous reaction mixture was obtained. As verified by HPLC measurements, the conversion of monomers into the polymer P4 has grown very rapidly. After about 10 minutes, all monomers were already reacted.

Although polymers can be produced in this way, controlled production of polymers is difficult in practice. The polymers P4 were therefore not considered further. 1 .6 Statistical polymer P5

A fifth polymer P5 with random or random monomer distribution was in turn prepared like polymer P3 (Chapter 1 .4) (temperature also 80 ° C). However, instead of the pH of 8, a pH of 1 was set (by the added amount of base). HPLC measurements have shown that, under these conditions, some of the acrylate or methacrylate monomers are already in the polymerization reaction and then hydro- lysed. This means that methoxy-polyethylene glycol groups or hydroxyethyl groups are split off, which then can no longer be bound to the polymer or are. However, as with polymer P3, the conversion of the monomers increased essentially linearly over a period of about 50 minutes. Accordingly, even under these conditions, the reaction can be well controlled.

The molar ratio of methacrylic acid units: methoxy-polyethylene glycol methacrylate: 2-hydroxyethyl acrylate was 4: 2: 1 and the solids content of the polymer P5 about 40 wt .-%. 2. polydispersity

The polydispersity of the polymers according to the invention is about 1 .2 throughout. In contrast, the comparative polymer R1 prepared by polymer-analogous esterification has a polydispersity of about 1.5.

3. Mortar Tests In order to determine the dispersing effect of the polymers, in each case the slump of prepared cement pastes was measured at different times on the basis of EN 1015-3. Cement (type CEM I) and water (w / c = 0.31) were used to make the mortar.

It has been shown that the novel copolymers show a good and long-lasting liquefaction effect.

A comparison of the polymers P3 and P5 shows the following: Polymer P3 is used to measure a spread in cement pastes immediately after application of 1 60 mm, while polymer P5 gives a yield of 80 mm. This shows that particularly preferred polymers are obtained in particular with a solution polymerization at a pH of about 8.

However, the embodiments described above are to be understood merely as illustrative examples, which may be modified as desired within the scope of the invention.

Claims

claims

Process for the preparation of a copolymer, in particular a dispersant for solid particles, in particular a dispersant for mineral binder compositions, wherein ionizable monomers m1 and side-chain-carrying monomers m2 are polymerized by nitroxide-mediated solution polymerization to a copolymer, wherein the polymerization in the presence of an agent which a carboxy group-carrying and phosphorous alkoxyamine is carried out.

Process according to Claim 1, characterized in that the solution polymerization is carried out in a polar solvent, in particular in an aqueous solvent, preferably in water.

Process according to at least one of Claims 1 - 2, characterized in that the agent represents a compound of the formula X:

in which

R ^{11 is} a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 3 to 4, carbon atoms;

R ¹² and R ¹³ , each independently of one another, are hydrogen or a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 3 to 4, carbon atoms;

R ¹⁴ and R ¹⁵ , each independently of one another, are a linear or branched alkyl radical having 1 to 6, in particular 2 to 4, preferably 2 to 3, carbon atoms; R ¹⁶ and R ¹⁷ , each independently of one another, are a linear or branched alkyl radical having 1 to 6, in particular 1 to 4, preferably 1 to 2, carbon atoms;

T, independently of one another, represents H ⁺ , an alkali metal ion, an alkaline earth metal ion, a divalent or trivalent metal ion, an ammonium ion or an organic ammonium group.

4. The method according to at least one of claims 1-3, characterized in that the agent has exactly one carboxy group and exactly one nitroxide group. 5. The method according to at least one of claims 1 - 4, characterized in that the nitroxide-mediated solution polymerization at a pH in the range of 7.5 - 13, in particular 8 - 12, in particular 8 - 10, preferably 9 - 1 1, is carried out.

6. The method according to at least one of claims 1-5, characterized in that the nitroxide-mediated solution polymerization in the presence of a base, in particular in the presence of an alkali metal hydroxide and / or an alkali metal bicarbonate, in particular in the presence of sodium Hydroxide and / or sodium bicarbonate, takes place. 7. The method according to at least one of claims 1-6, characterized in that the nitroxide-mediated solution polymerization at a temperature of 40 - 120 ° C, in particular 60 - 1 10 ° C, preferably 80 - 100 ° C, is performed.

8. The method according to at least one of claims 1-7, characterized in that the monomers are converted into a copolymer having a block structure, wherein the side chain-carrying monomers m2 substantially in at least a first block A and ionizable monomers m1 substantially in at least a second block B, are present.

9. The method according to at least one of claims 1-8, characterized in that the ionizable monomers m1 and the side chain-bearing monomers m2 are polymerized together to form a portion having a concentration gradient and / or a gradient structure.

10. The method according to at least one of claims 1-9, characterized in that the ionizable monomers m1 have a structure according to formula I:

and the side-chain-bearing monomers m2 have a structure according to formula II:

in which

R ¹ , each independently of one another, for -COOM, -SO 2 -OM,

-0-PO (OM) ₂ and / or -PO (OM) ₂ , R ² , R ³ , R ⁵ and R ⁶ , each independently of one another, are H or an alkyl group having 1 to 5 carbon atoms,

X, in each case independently of one another, represents -O- or -NH-,

R ^{8 is} a group of the formula - [AO] _n -R ^a , where A = C 2 -C 4 -alkylene, R ^{a is} H, a C 1 - to C 20 -alkyl group, -cycloalkyl group or -alkylaryl group, and n = 2-250, especially 10-200.

1 1. Method according to at least one of claims 1 - 10, characterized in that a molar ratio of the ionizable monomers m1 used to the side chain-carrying monomers used m2 in the range of 0.5 - 6, especially 0.7 - 4, preferably 0.9 - 3.8, more preferably 1. 0 - 3.7 or 2 - 3.5.

12. The method according to at least one of claims 10 - 1 1, characterized in that R ¹ = COOM; R ² and R ⁵ , independently of one another, are H, -CH 3 or mixtures thereof; R ³ and R ⁶ , independently of one another, are H or -CH 3, preferably H; R ⁴ and R ⁷ , independently of one another, stand for H or -COOM, preferably for H; and where

X is at least 75 mole%, especially at least 90 mole%, especially at least 99 mole% of all monomers m2 is -O-.

13. The method according to at least one of claims 1-12, characterized in that during the polymerization at least one further Monomer ms is present and is polymerized, which is in particular a monomer of formula III:

wherein R ^{5 '} , R ^6' , R ^{7 '} , m' and p 'are defined as R ⁵ , R ⁶ , R ⁷ , m and p in claim 10;

Y, each independently, is a chemical bond or -O-;

Z, each independently, is a chemical bond, -O- or -NH-;

R ⁹ , in each case independently of one another, represents an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or an acetoxyalkyl group, each having 1-20 C atoms.

14. A copolymer obtainable by a process according to any one of claims 1-13.

15. Use of a copolymer according to claim 14 as a dispersant for solid particles, in particular as a dispersant for a mineral binder composition, in particular for liquefaction, for water reduction and / or for prolonging the processability of a mineral binder composition, preferably a mortar or concrete composition.