EP2102143A1

EP2102143A1 - Method for producing polymerizable carboxylic acid esters having alkoxy groups

Info

Publication number: EP2102143A1
Application number: EP07857240A
Authority: EP
Inventors: Paola Uribe Arocha; Joachim Pakusch; Stefan Becker; Thomas GÖTZ; Sylke Haremza; Rolf Gulden
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2006-12-08
Filing date: 2007-12-03
Publication date: 2009-09-23
Also published as: KR20090096514A; CA2669954A1; US20100069532A1; MX2009005532A; WO2008068213A1; JP2010511760A; CN101553458A; JP5328667B2

Abstract

A method for producing radically polymerizable carboxylic acid esters by reacting ethylenically unsaturated carboxylic acids, carboxylic acid anhydrides, or carboxylic acid halogenides (collectively referred to as carboxylic acid components) with a hydroxyl compound comprising at least 60 weight-% C<SUB>2</SUB>- to C<SUB>4</SUB>-alkoxy groups (referred to in short as a polyalkoxy compound), characterized in that the reaction occurs in the presence of a polymerization inhibitor and a reducing agent.

Description

Process for the preparation of polymerizable carboxylic acid esters with alkoxy groups

description

The present invention relates to a process for the preparation of free-radically polymerizable carboxylic acid esters by reacting ethylenically unsaturated carboxylic acids, carboxylic anhydrides or carboxylic acid halides (collectively referred to as carboxylic acid component) with a hydroxyl compound which consists of at least 60 wt .-% of C2 to C4 alkoxy groups (short referred to as polyalkoxy compound), characterized in that the reaction

in the presence of a polymerization inhibitor and

- A reducing agent takes place.

The invention further relates to copolymers containing the carboxylic acid esters, and the use of the copolymers as a fluidizing additive in cementitious preparations

Free-radically polymerizable carboxylic acid esters, in particular monoesters of poly-C 2 -C 4 -alkylene glycols with acrylic acid or methacrylic acid, hereinafter also referred to as (poly-C 2 -C 4 -alkylene glycol) mono (meth) acrylate, are described, for example. B. for the production of comb polymers with poly-C2-C4-alkylene ether side chains are used. Due to their surface-active properties, the latter are used in a variety of ways, for example as detergent additives such as incrustation inhibitors, grayness inhibitors and soil release agents, and as coating raw materials, as formulation additives for active ingredient preparations in medicine and crop protection.

Anionic comb polymers having poly-C 2 -C 4 -alkylene ether side chains and carboxylate groups on the polymer backbone, in particular those having C 1 -C 10 -alkylpolyethylene glycol side chains, are used, for example, as flow agents for mineral binders, in particular for cementitious binders such as mortars, cement-based plasters and, in particular, concrete ,

The preparation of (poly-C2-C4-alkylene glycol) -mono (meth) acrylic acid esters is usually carried out by esterification of an OH-bearing P0IV-C2-C4-alkylene glycol with acrylic acid or methacrylic acid.

Different methods are described in the literature.

DE-A 1 110866 describes u. A. the reaction of Monoalkylpolyalkylenglykolen with acid chlorides of ethylenically unsaturated carboxylic acids, wherein the acid chloride is used in excess. The resulting crude product of the ester naturally contains not yet reacted excess acid chloride, which interferes with further reactions and must be removed by distillation consuming. The quality of the (poly-C2-C4-alkylene glycol) mono (meth) acrylic esters thus produced is not satisfactory.

No. 4,075,441 describes the preparation of alkylphenoxy (polyethylene glycol) monoesters of olefinically unsaturated carboxylic acids by esterification of polyethylene glycol mono (alkylphenyl) ethers with the corresponding acid in the presence of p-toluenesulfonic acid or by reaction with the acid chloride in the presence of a amine. The conversions achieved and the quality of the alkylphenoxy- (polyethyleneglycol) monoesters thus prepared are unsatisfactory.

WO 01/74736 describes a process for the preparation of copolymers of (poly-C 2 -C 4 -alkylene glycol) mono (meth) acrylic esters with acrylic acid or methacrylic acid by copolymerization of these monomers, wherein the preparation of the (P0IV-C2- C 4 -alkylene glycol) mono (meth) acrylic acid ester by reaction of polyalkylene glycols with (meth) acrylic anhydrides in the presence of amines. For this purpose, the anhydride is used in excess of at least 10 mol .-%, based on the stoichiometry of the reaction. Despite this excess, the rate of esterification is low. Own investigations by the inventors have also shown that the conversions achieved in the esterification are low and the esters thus prepared contain not only free anhydride but also considerable amounts of unreacted polyalkylene glycols, which improve the quality of the subsequently prepared polymers, especially with regard to their use as Concrete flux, adversely affected.

WO 2006/024538 describes a method, in which with an at least one OH group-bearing P0IV-C2-C4-alkylene glycol compound, acrylic anhydride or methacrylic anhydride in the presence of a base, the base being selected from basic compounds at 90 ⁰ C have a solubility of not more than 10 g / l and wherein (meth) acrylic anhydride A and P0IV-C2-C4 alkylene glycol compound P in a molar ratio A: P in the range of 1: 1 to 1, 095: 1 is used. By this method, the quality of the carboxylic acid ester and also the rate of turnover could be improved.

WO 2006/024538 also describes the use of a polymerization inhibitor in the esterification. Suitable polymerization inhibitors often require oxygen for their effectiveness; In addition, oxygen itself can also act as an inhibitor. A disadvantage of the presence of oxygen, however, is a formation of peroxides. Peroxides lead in polyalkylene oxides z. For example, to ether cleavage and by unwanted cross-linking reactions to carboxylic acid esters with more than one polymerizable group. Such polyvalent carboxylic esters lead in the subsequent polymerization to crosslinks and a broad molecular weight distribution. For many applications, especially for use as a fluidizing additive in cementitious formulations uniform copolymers are advantageous.

It is therefore an object of the present invention to provide a process for the preparation of free-radically polymerizable carboxylic acid esters which give copolymers which are copolymerized in the copolymerization and are particularly suitable as a fluidizing additive in cementitious preparations.

Accordingly, the method defined above was found.

to the constituents of the carboxylic acid ester

Suitable carboxylic acid components are all free-radically polymerizable carboxylic acids, carboxylic anhydrides or carboxylic acid halides. It can be z. B. to dicarboxylic acids or their anhydrides, eg. For example, be maleic acid, maleic anhydride, fumaric acid, itaconic acid or itaconic anhydride. Preference is given to monocarboxylic acids, such as acrylic acid or methacrylic acid, very particular preference is given to dimeric anhydrides of the monocarboxylic acids, in particular to acrylic anhydride or methacrylic anhydride.

The polyalkoxy compound preferably has one or two, more preferably two, hydroxyl groups which react with the carboxylic acid components to form esters.

The polyalkoxy compound is preferably at least 80% by weight of C 2 to C 4 alkoxy groups. Ethoxy groups, propoxy groups or mixtures thereof are preferred as C 2 -C 4 alkoxy groups; ethoxy groups are particularly preferred. In a preferred embodiment, at least 70% by weight, particularly preferably at least 90% by weight and in particular 100% by weight, of the alkoxy groups are ethoxy groups.

The polyalkoxy compound usually has at least 3, often at least 5 and especially at least 10 and usually not more than 400, often not more than 300, z. B. 10 to 200 and especially 10 to 150 alkoxy groups. The compounds may be linear or branched and generally have on average at least one, usually terminal, free OH group in the molecule. The remaining end groups may be, for example, OH groups, alkyloxy groups having preferably 1 to 10 C atoms, phenyloxy or benzyloxy groups, acyloxy groups having preferably 1 to 10 C atoms, O-SOsH groups or O-POsH2 groups, the two being the latter groups may also be present as anionic groups. In a preferred embodiment, a polyalkyloxy compound is used in which one end group is an OH group and the other end group (s) alkyloxy group (s) with 1 to 10 and in particular having 1 to 4 carbon atoms such as ethoxy, n-propoxy, isopropoxy, n-butoxy, 2-butoxy or tert-butoxy, and especially methoxy is (are).

Preferred are linear polyalkoxy compounds having about one free OH group per molecule (i.e., about 0.9 to 1, 1 free OH groups on average). Such compounds can be described by the general formula P:

HO- (AO) _n -R ¹ (P)

wherein n denotes the number of repeating units and generally represents a number in the range from 3 to 400, in particular in the range from 5 to 300, particularly preferably in the range from 10 to 200 and very particularly preferably in the range from 10 to 150,

A is C ₂ -C ₄ alkylene, such as 1, 2-ethanediyl, 1, 3-propanediyl, 1, 2-propanediyl, 1, 2-butanediyl or 1, 4-butanediyl, and

R ^{1 is} hydrogen, alkyl having preferably 1 to 10 and in particular 1 to 4 C atoms, phenyl, benzyl, acyl (= C (O) -alkyl) having preferably 1 to 10 C atoms, SO 2 H groups or PO 3 H 2, in particular C 1 -Cio-alkyl and particularly preferably CrC ₄ -AlkVl and especially methyl or ethyl.

Most preferably A is CH 2 -CH 2 or

CH ₂ -CH ™ ₃

Most preferably, A is CH 2 -CH 2

Accordingly, a very particularly preferred embodiment of the invention relates to a process in which the alkoxy compound is a polyethylene glycol mono (C 1 -C 10 -alkyl) ether, ie a mono-C 1 -C 10 -alkyl ether, in particular a mono-C 1 -C ₄ -alkyl ether and specifically, the methyl or ethyl ether of a linear polyethylene glycol.

Preferably, the polyalkoxy compound has a number average molecular weight (determined by GPC) in the range from 250 to 20,000 and in particular in the range from 400 to 10,000.

The free-radically polymerizable carboxylic acid ester is correspondingly preferably the acrylic or methacrylic acid ester of the above polyalkoxy compound. For the production process of the carboxylic acid ester

According to the invention, the polymerizable carboxylic acid ester is prepared in the presence of a polymerization inhibitor.

Preference is given to polymerization inhibitors selected from sterically hindered nitro oxides, cerium (III) compounds and sterically hindered phenols and mixtures thereof and mixtures thereof with oxygen.

Particularly suitable are in particular phenols such as hydroquinone, hydroquinone monomethyl ether, especially sterically hindered phenols such as 2,6-di-tert-butylphenol or 2,6-di-tert-butyl-4-methylphenol, furthermore thiazines such as phenothiazine or methylene blue , Cerium (III) salts such as cerium (III) acetate and nitroxides, especially sterically hindered nitroxides, d. H. Nitroxides of secondary amines which carry 3 alkyl groups each at the carbon atoms which are adjacent to the nitroxide group, each 2 of these alkyl groups, in particular those which are not located on the same carbon atom, with the nitrogen atom of the nitroxide group or the carbon atom to which they are attached form a saturated 5- or 6-membered ring, such as, for example, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) or 4-hydroxy-2,2,6, 6-tetramethylpiperidine-1-oxyl (OH-TEMPO), mixtures of the aforementioned inhibitors, mixtures of the aforementioned inhibitors with oxygen, for. In the form of air, and mixtures of mixtures of the aforementioned inhibitors with oxygen, e.g. B. in the form of air. Preferred inhibitors are the abovementioned sterically hindered nitroxides, cerium (III) compounds and sterically hindered phenols and mixtures thereof and mixtures of such inhibitors with oxygen and mixtures of mixtures of these inhibitors with oxygen, eg. B. in the form of air. Particularly preferred are inhibitor systems comprising at least one sterically hindered nitroxide and another component selected from a hindered phenol and a cerium (III) compound, as well as mixtures thereof with oxygen, e.g. in the form of air.

The amount of the polymerization inhibitor may in particular be up to 2% by weight, based on the total amount of carboxylic acid component and alkoxy compound. The inhibitors are advantageously used in amounts of from 10 ppm to 1000 ppm, based on the total amount of carboxylic acid component and polyalkoxy compound. In the case of inhibitor mixtures, this information refers to the total amount of components except oxygen.

According to the invention, the polymerizable carboxylic acid ester is further prepared in the presence of a reducing agent.

Suitable reducing agents are, in particular, phosphorus- or sulfur-containing compounds. As sulfur-containing compounds are z. B sodium disulfide, sodium thiosulfate or mercaptans, such as butyl mercaptan, mercaptoacetic acid, mercaptopropionic acid or mercaptoethanol called.

The reducing agent is particularly preferably phosphorus-containing compounds which are to be understood as both inorganic and organic phosphorus compounds. The inorganic phosphorus compounds to be used according to the invention preferably comprise the oxo acids of the phosphorus and their salts which are soluble or dispersible in the reaction medium, preferably their alkali metal, alkaline earth metal or ammonium salts.

Examples of suitable inorganic phosphorus compounds are: phosphinic acid (H2PO2) and the salts derived therefrom, such as sodium phosphinate (monohydrate), potassium phosphinate, ammonium phosphinate; Hypodiphosphonic acid (H4P2O4) and the salts derived therefrom; Phosphonic acid (H3PO3) and the salts derived therefrom, such as sodium hydrogenphosphonate, sodium phosphonate, potassium hydrogenphosphonate, ammonium hydrogenphosphonate, ammonium phosphonate; Diphosphonic acid (H4P2O5) and the diphosphonates derived therefrom; Hypodiphosphoric acid (H4P2O6) and the hypodiphosphates derived therefrom; Diphosphoric acid (H4P2O7) and the diphosphates derived therefrom, as well as polyphosphoric acids and their salts, e.g. Sodium triphosphate.

Preferably, the carboxylic acid ester in the presence of phosphinic acid (H3PO2) or the salts derived therefrom z. Sodium hydrogenphosphonate, sodium phosphonate, potassium hydrogenphosphonate, potassium phosphonate, ammonium hydrogenphosphonate, ammonium phosphonate. Particular preference is given to sodium phosphinate monohydrate and / or phosphonic acid.

Phosphorus-containing compounds further include organophosphorus compounds such as urea phosphate, methane diphosphonic acid, propane-1, 2,3-triphosphonic acid, butane-1, 2,3,4-tetraphosphonic acid, polyvinyl phosphonic acid, 1-aminoethane-1, 1-diphosphonic acid, diethyl ( 1-hydroxyethyl) phosphonate, diethylhydroxymethylphosphonate, 1-amino-1-phenyl-1, 1-diphosphonic acid, aminotrimethylenetetriphosphonic acid, ethylenediaminotetramethylenetetra-phosphonic acid, ethylenetriaminopentamethylenepentaphosphonic acid, ethylenediaminotetramethylenetetra-phosphonic acid, ethylenetriaminopentamethylenepentaphosphonic acid, ethylenediaminotetramethylenetetra-phosphonic acid, Ethylentriaminopentamethylenpentaphosphonsäure,

1-hydroxyethane-1, 1-diphosphonic acid, phosphonoacetic and phosphonopropionic acid and its salts, diethyl phosphite, dibutyl phosphite, diphenyl phosphite, triethyl phosphite, tributyl phosphite, triphenyl phosphite and tributyl phosphate. Ethylenically unsaturated phosphorus compounds such as vinyl phosphonate, vinyl phosphonate, Vinylphosphonatethylester, vinyl phosphate, Allylphosphonat or allyl phosphate are suitable.

Preferred organophosphorus compounds are 1-hydroxyethane-1, 1-diphosphonic acid, and their disodium and tetrasodium salts, aminotrimethylene-tri- phosphonic acid and the pentasodium salt and ethylenediaminotetramethylenetetraphosphonic acid and its salt.

Often it is advantageous to combine several phosphorus compounds, such as sodium phosphinate monohydrate with phosphonic acid, phosphonic acid with 1-hydroxyethane-1, 1-diphosphonic acid disodium salt and / or Aminotrimethylentriphosphonsäure and / or 1-hydroxyethane-1, 1-diphosphonic acid. Si can be mixed together in any ratio and used in the polymerization.

The amount of reducing agent, preferably the phosphorus-containing compound is preferably 0.01 to 5 parts by weight, preferably 0.03 to 3 parts by weight, in particular 0.05 to 2 parts by weight per 100 parts by weight of carboxylic acid component and polyalkoxy compound.

The preparation of the polymerizable carboxylic acid ester moreover preferably takes place at a reduced oxygen content.

Preferably, the reaction is carried out in the presence of a gas mixture having an oxygen concentration of 1 to 15% by volume.

The reaction of the anhydride with the compound P can be carried out in all apparatuses customary for such reactions, eg. B. in a stirred tank, in stirred tank cascades, autoclaves, tubular reactors or kneaders. The reaction space available in the apparatuses is preferably not completely filled with the reaction mixture, in general only a maximum of 90% by volume, in particular only a maximum of 80% by volume, is filled with the reaction mixture. The remaining space is occupied by the gas mixture. The gas mixture is preferably passed continuously through the reaction space.

Moreover, the preparation is preferably carried out according to the method described in WO 2006/024538.

Preferably, therefore, the preparation of the polymerizable carboxylic acid ester in the presence of a base.

The base is preferably selected from basic compounds having at 90 ^° C. a solubility in the polyalkoxy compound of not more than 10 g / l, more preferably not more than 5 g / l.

Examples of suitable bases according to the invention include hydroxides, oxides, carbonates and bicarbonates of monovalent or divalent metal cations, in particular of elements of the first and second main group of the periodic table, ie Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ^2+, as well as mono- or divalent transition metal cations such as Ag ⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Cd ²⁺ , Sn ²⁺ , Pb ²⁺ , Ce ²⁺ . The hydroxides, oxides, carbonates and bicarbonates of cations of the alkali and alkaline earth metals and of Zn ²⁺ and in particular of Mg ²⁺ or Ca ²⁺ and particularly preferably of Na ⁺ or K ^{+ are} preferred. Preferred among these are the hydroxides and carbonates of these metal ions, in particular the alkali metal carbonates and alkali metal hydroxides and especially sodium carbonate, potassium carbonate, potassium hydroxide and sodium hydroxide. In particular, lithium hydroxide and lithium carbonate are also suitable. The base is preferably used in an amount of 0.05 to 0.5 base equivalents and in particular in an amount of 0.1 to 0.4 base equivalents, based on the polyalkoxy compound, wherein larger amounts of base z. B. to 1 base equivalent usually not disadvantageous. It should be noted that in the case of hydroxides and bicarbonates, the base equivalents correspond to the molar equivalents used, whereas 1 molar equivalent of a carbonate or oxide corresponds in each case to 2 base equivalents.

Preferably, the carboxylic acid component is used in excess to prepare the radically polymerizable carboxylic acid ester. The molar ratio of the reactive carboxylic acid groups of the carboxylic acid components to the hydroxyl groups of the polyalkyloxy compound may be e.g. B. 1: 0.5 to 5: 1, preferably 1: 1 to 5: 1 and most preferably 1, 2: 1 to 4: 1. The excess carboxylic acid components are copolymerized in the subsequent copolymerization. It should be noted that (meth) acrylic anhydride is a dimer having two carboxylic acid groups per (meth) acrylic anhydride). The term (meth) acrylic anhydride refers here and below to both acrylic anhydride or methacrylic anhydride and mixtures thereof. Preference is given to using (meth) acrylic anhydride in an excess, based on the polyalkylene oxide compound (which corresponds to a much greater excess, based on the reactive carboxylic acid groups). The excess of (meth) acrylic anhydride is in a preferred embodiment 9.5 mol%, preferably 9 mol%, in particular 8.5 mol%, and especially 8 mol%, based on 1 mol of compound P (polyalkylene oxide ), ie the amount of (meth) acrylic anhydride is not more than 1, 095 mol, preferably not more than 1, 09 mol, in particular not more than 1, 085 mol and especially not more than 1, 08 moles per mole of compound P. Preference is given at least 1.005 mol, in particular at least 1.01 mol and more preferably at least 1.02 mol of (meth) acrylic anhydride per mole of compound P.

The reaction of the carboxylic acid components with the polyalkoxy compound is preferably carried out at temperatures in the range from 0 to 150 ^° C., in particular in the range from 20 to 130 ^° C. and more preferably in the range from 50 to 100 ^° C. The pressure prevailing in the reaction is for the Success of the reaction of minor importance and is usually in the range of 800 mbar to 2 bar and often at Ambient pressure. Preferably, the reaction is carried out in an inert gas atmosphere.

The reaction of the carboxylic acid components with the polyalkoxy compound is preferably carried out until a conversion of the compound P used of at least 80%, in particular at least 90% and particularly preferably at least 95% is achieved. The reaction times required for this purpose will generally not exceed 5 hours and often times less than 4 hours. The conversion can be monitored by ¹ H NMR spectroscopy of the reaction mixture, preferably in the presence of a strong acid such as trifluoroacetic acid.

The reaction of the carboxylic acid components with the polyalkoxy compound can be carried out in bulk, i. H. without addition of solvents, or in inert solvents or diluents. Inert solvents are usually aprotic compounds. The inert solvents include optionally halogenated aromatic hydrocarbons such as toluene, o-xylene, p-xylene, cumene, chlorobenzene, ethylbenzene, technical mixtures of alkylaromatics, aliphatic and cycloaliphatic hydrocarbons such as hexane, heptane, octane, isocatn, Cyclohexane, cycloheptene, technical Aliphatenmischungen, ketones such as acetone, methyl ethyl ketone, cyclohexanone, further ethers such as tetrahydrofuran, dioxane, diethyl ether, tert-butyl

Butyl methyl ether, and mixtures of the aforementioned solvents such. For example, toluene / hexane. Preferably, without solvent or only with very small amounts of solvent, usually less than 10 wt .-%, based on the starting materials, d. H. in substance, worked.

The reaction mixture therefore preferably contains less than 5% by weight of solvents such as water or organic solvents.

It has proven to be advantageous to carry out the reaction of the carboxylic acid component with the polyalkoxy compound in a reaction medium which contains less than 0.2% by weight and in particular less than 1000 ppm of water (determined by Karl Fischer titration). , The term "reaction medium" refers to the mixture of the reactants A and P with the base and with optionally used solvent and inhibitor. In the case of moisture-containing feed materials, it has proven useful to remove the water before the reaction, for. Example by distillation and particularly preferably by distillation with addition of an organic solvent that forms a low-boiling azeotrope with water. Examples of such solvents are the aforementioned aromatic solvents such as toluene, o-xylene, p-xylene, cumene, benzene, chlorobenzene, ethylbenzene and technical aromatics mixtures, furthermore aliphatic and cycloaliphatic solvents such as hexane, heptane, cyclohexane and technical Aliphatenmischungen and mixtures the aforementioned solvent. The reaction is usually carried out by reacting the reaction mixture containing the polyalkoxy compound and the carboxylic acid component and the base and optionally solvent, inhibitor and reducing agent in a suitable reaction vessel at the temperatures indicated above. Preference is given to the polyalkoxy compound and the base and optionally the solvent before and are d carboxylic acid component.

If the feedstocks contain water, it is preferable to remove the water prior to adding the carboxylic acid components.

The reaction of the polyalkoxy compound with the carboxylic acid Koponeneten leads to a mixture containing the polymerizable carboxylic acid ester and, depending on the amount of the carboxylic acid components, if appropriate, also polymerizable carboxylic acid Koponenten.

To the copolymers and their use

The resulting radically polymerizable carboxylic acid ester is preferably used for the preparation of homopolymers or copolymers.

In particular, the free-radically polymerizable carboxylic acid esters can be used without prior isolation from the product mixture of the esterification.

In the case of the copolymers, the other required monomers can be simply added to the product mixture.

Preferred copolymers are composed of:

From 10 to 99.9% by weight, particularly preferably from 50 to 99% by weight, and very particularly preferably from 70 to 97% by weight, of the free-radically polymerizable carboxylic ester (A)

0.1 to 50 wt .-% wt:%, more preferably 1 to 30 wt.% And most preferably 2 to 15 wt .-% acrylic acid or methacrylic acid (B) and

0 to 30% by weight, particularly preferably 0 to 20% by weight and very particularly preferably 0 to 10% by weight of further monomers (C)

Examples of monomers C) are:

C1 monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 carbon atoms such as crotonic acid, isocrotonic acid, maleic acid, fumaric acid and itaconic acid, C2 alkyl esters of monoethylenically unsaturated mono- and di-Cs-Cs-carboxylic acids, in particular of acrylic acid and methacrylic acid with Ci-Cio Alkanols or C 3 -C 10 cycloalkanols, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate and the corresponding methacrylic acid esters, C 3 hydroxyalkyl esters monoethylenically unsaturated Mono- and di-Cs-Cs-carboxylic acids, in particular of acrylic acid and of methacrylic acid such as 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate and 4-hydroxybutyl methacrylate, C4 monoethylenically unsaturated nitriles such as acrylonitrile .

C5 vinylaromatic monomers such as styrene and vinyltoluenes,

C6 monoethylenically unsaturated sulfonic acids and phosphonic acids and their

Salts, in particular their alkali metal salts, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acryloxyethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylphosphonic acid, allylphosphonic acid, 2-

Acryloxyethanephosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, and

C7 amino-carrying monomers and their protonation and their quaternization products such as [2- (N, N-dimethylamino) ethyl] acrylate, [2- (N, N-dimethylamino) ethyl] methacrylate, [3- (N , N-dimethylamino) propyl] acrylate, [2- (N, N-dimethylamino) propyl] methacrylate, [2- (N, N, N-trimethylammonium) ethyl] acrylate, [2- (N, N, N trimethylammonium) ethyl] methacrylate, [3- (N, N ₁ NT rimethylammonium) - propyl] acrylate [2- (N, N, N-trimethyl ammonium) propyl] methacrylate in the form of their chlorides, sulfates, and methosulfates.

Preferred monomers C are the monomers C1, C3 and C6. The proportion of monoethylenically unsaturated monomers in the total amount of the monomers to be polymerized will generally not exceed 30% by weight and in particular 10% by weight. In a particularly preferred embodiment, one uses no or less than 1 wt .-%, based on the total amount of the monomers C to be polymerized, based on the total amount of the monomers to be polymerized.

In addition, it may be expedient to increase the molecular weight of the polymers, the copolymerization in the presence of small amounts of multi-ethylenically unsaturated monomers with z. B. 2, 3 or 4 polymerizable double bonds perform (crosslinker). Examples thereof are diesters and triesters of ethylenically unsaturated carboxylic acids, in particular the bis- and trisacrylates of diols or polyols having 3 or more OH groups, eg. As the bisacrylates and the bis methacrylates of ethylene glycol, diethylene glycol, trietylene glycol, neopentyl glycol or polyethylene glycols. Such crosslinkers are used, if desired, in an amount of generally 0.01 to 5 wt .-% based on the total amount of the monomers to be polymerized. Preferably, less than 0.01 wt .-% and in particular no Vernetzermonomere be used. The copolymerization of the carboxylic acid ester with acrylic acid and / or methacrylic acid and optionally other monomers is usually carried out in the presence of free-radical-forming compounds, so-called initiators. Such compounds are usually used in amounts of up to 30 wt .-%, preferably 0.05 to 15 wt .-%, in particular 0.2 to 8 wt .-%, based on the monomers to be polymerized. In the case of initiators consisting of several constituents (initiator systems, for example, in the case of redox initiator systems), the above weights refer to the sum of the components.

Suitable initiators are, for example, organic peroxides and hydroperoxides, furthermore peroxodisulfates, percarbonates, peroxide esters, hydrogen peroxide and azo compounds. Examples of initiators are hydrogen peroxide, dicyclohexyl peroxydicarbonate, diacetyl peroxide, di-tert-butyl peroxide, diamyl peroxide, dioctanoyl peroxide, dicanoanoyl peroxide, dilauroyl peroxide, dibenzoyl peroxide, bis (o-toluyl) peroxide, succinyl peroxide, methyl ethyl ketone peroxide, di-tert. Butyl hydroperoxide, acetylacetone peroxide, butyl peracetate, tert-butyl per- malate, tert-butyl perisobutyrate, tert-butyl perpivalate, tert-butyl peroctoate, tert-butyl pernodecanoate, tert-butyl perbenzoate, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl pernodecanoate tert-butyl perpivalate, tert-butyl perpivalate, tert-butyl perbenzoate, tert-butyl peroxy-2-ethylhexanoate and diisopropyl peroxydicarbamate; furthermore lithium, sodium, potassium and ammonium peroxodisulfate, azo initiators 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis [2-methyl-N- ( 2-hydroxyethyl) propionamide, 1,1'-azobis (1-cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (N, N'-dimethyleneisobutyroamidine) dihydrochloride , and 2,2'-azobis (2-amidinopropane) dihydrochloride. as well as the redox initiator systems explained below.

Redox initiator systems contain at least one peroxide-containing compound in combination with a redox coinitiator, e.g. a reducing sulfur compound, e.g. Bisulfites, sulfites, thiosulfates, dithionites and tetrathionates of alkali metals or of ammonium compounds. So you can use combinations of peroxodisulfates with alkali metal or ammonium hydrogen sulfites, z. For example, ammonium peroxodisulfate and ammonium disulfite. The amount of the peroxide-containing compound to the redox coinitiator is 30: 1 to 0.05: 1.

The initiators can be used alone or mixed with each other, for. B. mixtures of hydrogen peroxide and sodium peroxodisulfate.

The initiators can be either water-soluble or water-insoluble or only slightly soluble. Water-soluble initiators are preferably used for the polymerization in an aqueous medium, ie initiators which are soluble in the aqueous polymerization medium in the concentration customarily used for the polymerization. These include peroxodisulfates, azo initiators with ionic groups, organic Hydroperoxides having up to 6 C atoms, acetone hydroperoxide, methyl ethyl ketone hydroperoxide and hydrogen peroxide, as well as the abovementioned redox initiators.

In combination with the initiators or the Redoxinitiatorsystemen transition metal catalysts may additionally be used, for. Salts of iron, cobalt, nickel, copper, vanadium and manganese. Suitable salts are e.g. Iron (II) sulfate, cobalt (II) chloride, nickel (II) sulfate, or copper (I) chloride. Based on the monomers, the reducing transition metal salt is used in a concentration of 0.1 ppm to 1000 ppm. So you can use combinations of hydrogen peroxide with iron (II) salts, such as 0.5 to 30% hydrogen peroxide and 0.1 to 500 ppm Mohr's salt.

In the copolymerization in organic solvents, redox coinitiators and / or transition metal catalysts can also be used in combination with the abovementioned initiators, eg. As benzoin, dimethylaniline, ascorbic acid and soluble in organic solvents complexes of heavy metals such as copper, cobalt, iron, manganese, nickel and chromium. The amounts of redox coinitiators or transition metal catalysts usually used are about 0.1 to 1000 ppm, based on the amounts of monomers used.

In order to control the average molecular weight of the polymers obtainable according to the invention, it is often expedient to carry out the copolymerization according to the invention in the presence of regulators. Conventional regulators can be used for this purpose, in particular compounds containing organic SH groups, in particular water-soluble compounds containing SH groups, such as 2-mercaptoethanol,

2-mercaptopropanol, 3-mercaptopropionic acid, cysteine, N-acetylcysteine, furthermore phosphorus (III) or phosphorus (I) compounds such as alkali metal or alkaline earth metal hypophosphites, eg. As sodium hypophosphite, and hydrogen sulfites such as sodium hydrogen sulfite. The polymerization regulators are generally used in amounts of from 0.05 to 10% by weight, in particular from 0.1 to 2% by weight, based on the monomers. Preferred regulators are the abovementioned SH-group-carrying compounds, in particular water-soluble compounds bearing SH groups, such as 2-mercaptoethanol, 2-mercaptopropanol, 3-mercaptopropionic acid, cysteine and N-acetylcysteine. In these compounds, it has proven particularly useful to use these in an amount of 0.05 to 2 wt .-%, in particular 0.1 to 1 wt .-%, based on the monomers. The abovementioned phosphorus (III) compounds and phosphorus (I) compounds as well as the hydrogen sulfites are usually obtained in relatively large quantities, eg. B. 0.5 to 10 wt .-% and in particular 1 to 8 wt .-%, based on the monomers to be polymerized monomers. Also by the choice of the appropriate solvent can be influenced on the average molecular weight. Thus, the polymerization in the presence of diluents with benzylic or allylic H atoms to a reduction in the average molecular weight by chain transfer. The copolymerization can be carried out by the customary polymerization processes, including solution, precipitation, suspension or bulk polymerization. Preference is given to the method of solution polymerization, ie the polymerization in solvents or diluents.

Suitable solvents or diluents include both aprotic solvents, e.g. B. the aforementioned aromatics such as toluene, o-xylene, p-xylene, cumene, chlorobenzene, ethylbenzene, technical mixtures of alkylaromatics, aliphatic and cycloaliphatic compounds such as cyclohexane and technical Aliphatenmischungen, ketones such as acetone, cyclohexanone and methyl ethyl ketone, ethers such as tetrahydrofuran, dioxane, Diethyl ether, tert-butyl methyl ether, and C 1 -C 4 -alkyl esters of aliphatic C 1 -C 4 -carboxylic acids such as methyl acetate and ethyl acetate, furthermore protic solvents such as glycols and glycol derivatives, polyalkylene glycols and their derivatives, C 1 -C 4 -alkanols, eg. For example, n-propanol, n-butanol, isopropanol, ethanol or methanol, and water and mixtures of water with Ci-C4-alkanols such. B. isopropanol / water mixtures. Preferably, the copolymerization process is carried out in water or a mixture of water with up to 60 wt .-% of Ci-C4-alkanols or glycols as a solvent or diluent. With particular preference, water is used as the sole solvent.

The copolymerization process is preferred with substantial or complete exclusion of oxygen, preferably in an inert gas stream, e.g. B. a nitrogen Ström performed.

The copolymerization process can be carried out in the usual apparatuses for polymerization. These include stirred tanks, stirred tank cascades, autoclaves, tube reactors and kneaders.

The copolymerization process usually takes place at temperatures in the range from 0 to 300 ^° C., preferably in the range from 40 to 120 ^° C. The polymerization time is usually in the range from 0.5 h to 15 h and in particular in the range from 2 to 6 h. The pressure prevailing in the polymerization is of minor importance for the success of the polymerization and is generally in the range from 800 mbar to 2 bar and often at ambient pressure. When using volatile solvents or volatile monomers, the pressure may be higher.

Depending on the choice of polymerization conditions, the copolymers obtainable generally have weight-average molecular weights (M _w ) in the range from 1000 to 200,000. With regard to the use of the polymers, those having a weight-average molecular weight of 5,000 to 100,000 are preferred. The weight-average molecular weight M _w can be determined in the usual way by gel permeation chromatography, as explained in the examples. The K values of the invention Copolymers obtainable by the method indicated below are preferably in the range from 20 to 45.

When the process is carried out as a solution polymerization in water, removal of the water is not required for many applications. Incidentally, an isolation of the polymer obtainable according to the invention can be carried out in a conventional manner, for. B. by spray drying of the polymerization mixture. If the polymerization is carried out in a steam-volatile solvent or solvent mixture, the solvent can be removed by passing in steam, thereby obtaining an aqueous solution or dispersion of the copolymer.

The resulting polymers or copolymers have a uniform molecular weight distribution. The weight average molecular weight Mw and the number average molecular weight Mn are determined by gel permeation chromatography.

For use

The copolymers are preferably obtained in the form of an aqueous dispersion or solution. The solids content is preferably 10 to 80 wt .-%, in particular 30 to 65 wt .-%.

The copolymers, in particular the copolymers of (meth) acrylic acid with (P0IV-C 2 -C 4 -alkylene glycol) mono (meth) acrylic acid, preferably the copolymers of methacrylic acid with polyethylene glycol mono (C 1 -C 10 -alkyl) monomethacrylates, are outstandingly suitable as additives for cementitious preparations, such as concrete or mortar and are characterized in particular by superior properties in terms of their liquefying effect. The present invention therefore also relates to the copolymers obtainable by the process according to the invention and in particular copolymers of polyethylene glycol mono (C 1 -C 10 -alkyl) monomethacrylate with methacrylic acid, and to their use in cementitious preparations, in particular as concrete flow agents.

By cement is meant, for example, Portland cement, alumina cement or mixed cement, such as pozzolanic cement, slag cement or other types. In particular, the copolymers according to the invention are suitable for cement mixtures containing predominantly and in particular at least 80% by weight, based on the cement constituent, of Portland cement as cement constituents. The copolymers of the invention are used for this purpose generally in an amount of 0.01 to 10 wt .-%, preferably 0.05 to 3 wt .-%, based on the total weight of the cement in the cement preparation. The copolymers may be added in solid form or as an aqueous solution to the ready-to-use cementitious composition. It is also possible to formulate copolymers present in solid form with the cement and to prepare the ready-to-use cement-containing preparations therefrom. The copolymer is preferably used in liquid, that is dissolved, emulsified or suspended form, for example in the form of the polymerization solution, in the preparation of the preparation, ie during mixing.

The copolymers can also be used in combination with the known concrete flow improvers and / or concrete liquefiers based on naphthalene-formaldehyde condensate sulfonate, melamine-formaldehyde condensate sulfonate, phenolsulfonic acid-formaldehyde condensate, lignosulfonates and gluconates. Furthermore, together with celluloses, e.g. As alkyl or hydroxyalkyl celluloses, starches or starch derivatives are used. Also, they may be used in combination with high molecular weight polyethylene oxides (weight-average molecular weight M _w in the range of 100,000 to 8,000,000).

Furthermore, conventional additives such as air-entraining agents, expansion agents, water repellents, setting retarders, setting accelerators, antifreeze agents, sealants, pigments, corrosion inhibitors, flow agents, injection aids, stabilizers or hollow microspheres can be added to the cementitious preparation. Such additives are described for example in EN 934.

In principle, the copolymers can also be used together with film-forming polymers. These are understood as meaning those polymers whose glass transition temperature is <65 ^° C., preferably <50 ^° C., more preferably <25 ^° C., and very particularly preferably <0 ^° C. With reference to the relationship between the glass transition temperature of homopolymers and the glass transition temperature of copolymers established by Fox (TG Fox, Bull. Am. Phys. Soc. (Ser.ll) 1, 1956, 123, one skilled in the art will be able to select suitable polymers suitable polymers are the styrene-butadiene polymers and styrene acrylates which are commercially available for this purpose (see, for example, BH Lutz in D. Distler (publisher), "Wässrige Polymerdispersionen" Wiley-VCH, Weinheim 1999, chapter 10.3 and 10.4, Pp. 230-252).

Furthermore, it is often advantageous if the copolymers are used together with anti-foaming agents. This prevents that when preparing the ready-to-use mineral building materials too much air in the form of air pores are introduced into the concrete, which would reduce the strength of the hardened mineral building material. Suitable antifoaming agents include, in particular, polyalkylene oxide-based antifoams, trialkyl phosphates such as tributyl phosphate, and silicone-based defoamers. Also suitable are the ethoxylation products and the propoxylation products of alcohols having 10 to 20 carbon atoms. men. Also suitable are the diesters of alkylene glycols or polyalkylene glycols and other conventional antifoams. Anti-foaming agents are usually used in amounts of 0.05 wt .-% to 10 wt .-%, and preferably from 0.5 to 5 wt .-%, based on the polymers.

The antifoams can be combined with the polymer in a variety of ways. For example, if the polymer is an aqueous solution, the antifoam agent may be added solid or dissolved to the polymer solution. If the antifoam agent is not soluble in the aqueous polymer solution, then emulsifiers or protective colloids may be added to stabilize it.

If the copolymer is in the form of a solid, as z. B. from a spray-drying or Sprühwirbelschichtgranulierung, so the antifoam agent can be mixed in as a solid or in the spray-drying process or spray granulation together with the polymer be made up.

The following examples are intended to illustrate the invention.

analytics:

a) Determination of the K value:

The K values of the aqueous sodium salt solutions of the copolymers were determined according to H. Fikentscher, Cellulose-Chemie, Volume 13, 58-64 and 71-74 (1932) in aqueous solution at a pH of 7, a temperature of 25 ⁰ C and a polymer concentration of the sodium salt of the copolymer of 1 wt .-% determined.

b) Determination of the solids content:

The determination is carried out by means of the MA30 analyzer from Satorius. For this purpose, a defined amount of the sample (about 0.5 to 1 g) is weighed into an aluminum tray and dried to constant weight at 90 ⁰ C. The percent solids (FG) is calculated as follows: FG = weight x 100 / weigh-in [wt%]

c) Molecular weight determination:

The number-average and weight-average molecular weight was determined by gel permeation chromatography (= GPC) with aqueous eluents. The GPC was performed with a device combination from Agilent (1100 series). This includes:

Begasser Model G 1322 A Isocratic Pump Model G 1310 A

Autosampler model G 1313 A

Column oven Model G 1316 A

Control module model G 1323 B

Differential refractometer model G 1362 A

The eluent used in the case of polymers dissolved in water is a 0.08 mol / l TRIS

Buffer (pH = 7.0) in distilled water + 0.15 mol / L chloride ions of NaCl and

HCl.

The separation took place in a separation column combination. The columns No. 789 and 790 (each 8 x 30 mm) from TosoHAAS with separating material are used

GMPWXL. The flow rate was 0.8 mL / min at a column temperature of 23 ^° C.

The calibration is carried out with polyethylene oxide standards from the company PPS with molecular weights of M = 194-1700000 [mol / g].

NMR analysis (sales determination)

To determine the conversion of the polyalkylene glycol, samples were taken from the reaction mixture at various times and treated with a little trifluoroacetic acid. The samples were analyzed by means of ¹ H-NMR spectroscopy at 20 ⁰ C, with the reference signal signals the end group of the polyalkylene glycol (in the case of a Polyalkylenglykolmethylethers the signal at 3.4 ppm), which coincides for the reactant and the product. For the determination of the conversion, the integral of a signal characteristic of the reaction product, generally the signal of the methylene protons at the oxygen of the ester group (usually at about 4.3 ppm) was determined and compared with the integral of the end group.

Preparation Examples:

Comparative example

In a 1 l glass reactor with anchor stirrer, thermometer, gas inlet, reflux condenser and dropping funnel, 450 g of methyl polyethylene glycol (M = 5000 g / mol), 90 mg of 2,6-di-tert-butyl-4-methylphenol, 9 mg of 4-hydroxy-N, N-2,2,6,6-tetramethylpiperidine-1-oxyl and 1, 59 g sodium carbonate (anhydrous) submitted. The mixture was heated to 90 ^° C. while introducing air. Then was added 17.36 g of methacrylic anhydride and allowed 2 hours at 90 ⁰ C ren react. Subsequently, the conversion was checked by 1 H-NMR spectroscopy

(100%), diluted with 256 g of water and cooled to room temperature. After esterification, polymerization was immediate.

Polymerization: In a 1-1 glass reactor with anchor stirrer, thermometer, nitrogen inlet,

Reflux and several feed vessels 290 g of water were initially charged and heated to 60 ⁰ C. With introduction of nitrogen was then added at 60 ⁰ C internal temperature with stirring, at the same time starting feed 1 within 4 h and feed 2 within 4.5 h continuously. In order to complete the copolymerization, polymerization was allowed to continue for a further 1 hour after completion of the feeds, then the contents of the reactor were cooled and neutralized with 25% strength sodium hydroxide solution.

Feed 1: Mixture of 250 g of the ester solution with 4.57 g of methacrylic acid and 0.41 g of mercaptoethanol. Feed 2: 1, 08 g aqueous sodium peroxodisulfate solution (7 wt .-%), 14 mg

water

The resulting solution had a solids content of 29.6% by weight and a pH of 6.6. The K value of the polymer was 94.8, the number average molecular weight Mn was 19700 and the weight average molecular weight Mw was 760000 daltons (quotient Mw / Mn as a measure of the uniformity: 38.6).

Inventive example. In a 1 l glass reactor with anchor stirrer, thermometer, gas inlet, reflux condenser and dropping funnel, 565 g of methyl polyethylene glycol (M = 5000 g / mol), 110 mg of 2,6-di-tert-butyl-4-methylphenol, 11 mg of 4 -Hydroxy-N, N-2,2,6,6-tetramethylpiperidin-1-oxyl and 1.99 g of sodium carbonate (anhydrous) are presented. The mixture was heated to 90 ° C while introducing air. Then 17.36 g of methacrylic anhydride were added and allowed to react at 90 ° C for 2 hours. Then the conversion was checked by means of 1 H-NMR spectroscopy (100%), diluted with 256 g of water with 2.26 g of hypophosphorous acid as reducing agent and cooled to room temperature. After esterification, polymerization was immediate.

polymerization:

In a 1-1 glass reactor with anchor stirrer, thermometer, nitrogen inlet,

Reflux and several feed vessels 280 g of water were submitted and heated to 60 ⁰ C. With introduction of nitrogen was then added at 60 ⁰ C internal temperature with stirring, at the same time starting feed 1 within 4 h and feed 2 within 4.5 h continuously. To complete the copolymerization was postpolymerized after completion of the feeds for 1 hour, then cooled the reactor contents and neutralized with 25% sodium hydroxide solution.

Feed 1: Mixture of 241 g of the ester solution with 4.44 g of methacrylic acid and 0.49 g of mercaptoethanol.

Feed 2: 1, 05 g aqueous sodium peroxodisulfate solution (7 wt .-%), 14 mg of water

The resulting solution had a solids content of 29.4% by weight and a pH of 6.7. The K value of the polymer was 52.4, the number average molecular weight Mn was 17300, and the weight average molecular weight Mw was 164,000 daltons (Mw / Mn as a measure of uniformity: 9.5).

Claims

claims

1. A process for preparing free-radically polymerizable carboxylic acid esters by reacting ethylenically unsaturated carboxylic acids, carboxylic acid or Carbonsäurehalogeniden (collectively referred to as carboxylic acid component) with a hydroxyl compound which consists of at least 60 wt .-% of C2 to C4 alkoxy groups (abbreviated as Polyalkoxy compound), characterized in that the reaction - takes place in the presence of a polymerization inhibitor and - a reducing agent.

2. Process according to claim 1, characterized in that the carboxylic acid component is maleic acid, itaconic acid, fumaric acid, acrylic acid, methacrylic acid or their anhydrides.

3. The method according to claim 1 or 2, characterized in that the polyalkoxy compound to at least 80 wt .-% of ethoxy groups, propoxy groups or mixtures thereof and one or two hydroxy groups (preferably a hydroxy group) has.

4. The method according to any one of claims 1 to 3, characterized in that it is in the polyalkoxy compound to polyethylene glycol mono (Ci-Cio-alkyl) - ether having a number average molecular weight of 400 to 10,000.

A process according to any one of claims 1 to 4, characterized in that the polymerization inhibitor is selected from polymerization inhibitors which are essential for their effectiveness, i. for radical formation, need oxygen.

6. The method according to any one of claims 1 to 5, characterized in that it is the reducing agent is a phosphorus or sulfur-containing compound, in particular hypophosphorous acid or salts thereof.

7. The method according to any one of claims 1 to 6, characterized in that the reaction takes place in the presence of a gas mixture having an oxygen concentration of 1 to 15% by volume.

8. The method according to any one of claims 1 to 7, characterized in that the reaction is carried out in the presence of a base.

9. The method according to any one of claims 1 to 8, characterized in that the reaction mixture contains less than 5 wt .-% water.

10. The method according to any one of claims 1 to 9, characterized in that the reaction in substance, i. in the presence of less than 5 wt .-% of water and / or organic solvents.

1 1. A process for the preparation of homopolymers or copolymers, characterized in that radically polymerizable carboxylic acid esters according to any one of claims 1 to 10 are used as monomers.

12. A process for the preparation of homopolymers or copolymers, characterized in that radically polymerizable carboxylic acid esters according to one of claims 1 to 10 are used without prior isolation from the product mixture of the esterification, wherein in the case of the copolymers, the monomers used are added to this product mixture.

13. The method according to any one of claims 11 or 12, characterized in that copolymers are prepared, which are composed of:

- 10 to 99.9 wt .-% of radically polymerizable carboxylic acid ester according to any one of claims 1 to 9. - 0.1 to 50 wt: -% acrylic acid or methacrylic acid and

- 0 to 30 wt .-% of other monomers.

14. Copolymers obtainable by a process of claims 11 to 13.

15. Use of the copolymers according to claim 14 as a fluidizing additive in cementitious preparations.