EP1171476A1

EP1171476A1 - Method for radical aqueous emulsion polymerization

Info

Publication number: EP1171476A1
Application number: EP00920548A
Authority: EP
Inventors: David Christie; Jerome Claverie; Saba Kanagasabapathy
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1999-04-01
Filing date: 2000-03-23
Publication date: 2002-01-16
Also published as: US6747102B1; DE19914953A1; WO2000059954A1; CA2365457A1; JP2002541274A

Abstract

The invention relates to a method for radical aqueous emulsion polymerization for producing an aqueous polymerization dispersion. According to the inventive method, ethylenically unsaturated monomers are polymerized by way of a radical polymerization initiator in the presence of controlling organometallic compounds.

Description

Radical initiated aqueous emulsion polymerization process

description

The present invention relates to a process of radically initiated aqueous emulsion polymerization for producing an aqueous polymer dispersion, in which at least one chemical compound (monomer) having at least one ethylenically unsaturated group is dispersed in an aqueous medium and at least in the presence of at least one free radical polymerization initiator an organometallic compound is polymerized.

Controlled polymerization reactions open up the possibility of synthesizing polymers with a certain molecular structure, defined molecular weight and low polydispersity and thus to adjust their property profile in a targeted manner. For this purpose, a large number of methods have been developed over the past 40 years, which are essentially based on anionic and cationic mechanisms (cf. 0.. Webster in Science 1991, 251, pages 887 to 893).

Compared to the ionic polymerization variants, radical polymerization reactions have the basic advantage that they can be carried out with a larger number of commercially important monomers and, moreover, can be carried out both in bulk, in solution, in suspension and in emulsion. Attempts to find suitable catalysts for controlled radical polymerization reactions have failed for a long time.

It has recently become known that N-oxyl radicals can be used to control radical-initiated polymerization reactions of ethylenically unsaturated monomers. In this connection, reference is made, for example, to the documents US-A 4 581 429, EP-A 735 052, WO 94/11412, US-A 5 322 912, US-A 5 412 047 and GB 1 124 009.

Wayland et al. Describe that organic metal complexes can also control radical polymerization processes. in J. Am. Chem. Soc. 1994, 116, pages 7943 to 7944, using the example of controlled radical solution polymerization of acrylates using special cobalt-porphyrin complexes. US Pat. No. 5,312,871 discloses the use of a catalyst system for the controlled polymerization of ethylenically unsaturated monomers, consisting of an alkyl or arylmeta11 compound, an organic ligand and a stable radical.

EP-A 841 346 discloses special cobalt, rhodium and iridium complexes for controlling free-radical polymerization reactions of ethylenically unsaturated monomers.

The application WO 87/03605 discloses the preparation of oligomeric compounds. The oligomers are produced by radical polymerization of ethylenically unsaturated monomers using special transition metal catalysts. However, the preparation of aqueous polymer dispersions by means of free-radically initiated aqueous emulsion polymerization is not disclosed.

Research Disclosure, December 1998, 416, pages 1595 to 1604 describes the controlling effect of special porphyrin, phthalocyanine and salen-iron complexes in the solution and substance polymerization of styrene. In addition to the azobisisobutyronitrile used as radical initiator, substituted alkyl bromides are used as the polymerization initiator. The porphyryne, phthalocyanine or salen-iron complexes are always in molar deficiency to the substituted alkyl bromide used as a radical polymerization initiator. Radical aqueous emulsion polymerizations are not included.

Correspondingly, EP-A 714 416 discloses the use of certain cobalt complexes with 4-toothed nitrogen ligands for controlling free-radical polymerization reactions both in solution and in emulsion. Only substituted aliphatic azo compounds are used as radical initiators.

US-A 5 763 548 also discloses a controlled radical polymerization process in which the controlling action of organometallic compounds is exerted.

WO 98/50436 describes the controlling action of special cobalt-oxime / boron fluoride complexes in the free-radically initiated aqueous emulsion polymerization. A characteristic of the disclosed process is that, in addition to the monomers, there are also hydrophobic solvents, such as, for example, higher alkanes or fatty alcohols are required to absorb the cobalt complex.

Makino et al. in Polymer Preprints Vol. 39, March 5 1998, pages 288 and 289 (Am. Chem. Soc; Polymer Chemistry Division) disclose a process for the controlled free radical aqueous emulsion polymerization of methyl methacrylate. Ethyl 2-bromoisobutanoate is used as the polymerization initiator. Furthermore, the emulsion polymerization takes place in the presence of a readily water-soluble copper (I) bispyridyl complex. The molar ratio of the polymerization initiator used to the water-soluble copper (I) bispyridyl complex is 1: 1. Sodium dodecyl sulfate is used as the dispersant.

5 According to Matyjaszewski et al. , Macromolecules 1998, 31, pages 5951 to 5954 are the Makino et al. results unsatisfactory. On the one hand, this is due to the fact that the copper (I) bispyridyl complex has too high a solubility in water and, moreover, the combination Cu ²⁺ / S0 ^2_ is disadvantageous for a controlling effect. Matyjaszewski et al. therefore recommend using nonionic polyethylene glycol ether as a dispersing agent and water- insoluble copper (I) dialkyl bispyridyl complexes as an organometallic compound.

5 In view of the above prior art, it was the object of the present invention to provide a process of controlled free-radical aqueous emulsion polymerization in which organometallic compounds other than the processes of the prior art exert the controlling effect 0, and in particular also in the presence of of sodium dodecyl sulfate as a dispersing agent requires satisfactory control, furthermore does not require the presence of a hydrophobic organic solvent and does not require any special polymerization initiators. 5

Accordingly, a method of free-radically initiated aqueous emulsion polymerization for the preparation of an aqueous polymer dispersion is provided, in which at least one monomer having at least one ethylenically unsaturated group is dispersed in an aqueous medium and polymerized in the presence of at least one organometallic compound by means of at least one free-radical polymerization initiator , which is characterized in that the at least one metal-organic compound on the one hand has the following structural feature 5 of the general formula I, With:

Me metal ion,

= either a covalent bond or a one to three atom covalent bridging chain, the atoms bound to the links of the chain are not counted and

^■ = a covalent bond to a neighboring atom,

has and on the other hand is such that at a temperature of 20 ° C and a pressure of 1 bar (absolute) their solubility in acidic, basic and / or neutral water is greater than their solubility in styrene.

Carrying out a free-radically initiated aqueous emulsion polymerization of monomers having at least one ethylenically unsaturated group has been described many times and is therefore sufficiently known to the person skilled in the art [cf. e.g. Encyclopedia of Polymer Science and Engineering, Vol. 8, pp. 659 ff. (1987); DC Blackley, in High Polymer Latices, Vol. 1, pp. 35 ff. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, pp. 246 ff., Chapter 5 (1972); D. Diederich, Chemistry in our time 24, pp. 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and dispersions of synthetic high polymers, F. Hölscher, Springer-Verlag, Berlin (1969)]. It is usually carried out in such a way that the at least one monomer, frequently with the use of dispersants, is dispersed in an aqueous medium and polymerized by means of a radical polymerization initiator. The method according to the invention differs from this procedure only in the additional presence of at least one metal organic compound which has the structural feature of the general formula I.

Suitable monomers having at least one ethylenically unsaturated group for the process according to the invention are in particular, in a simple manner, radically polymerizable monomers, such as, for example, ethylene, vinyl-aromatic monomers, such as styrene, α-methylstyrene, o-chlorostyrene or vinyltoluenes, esters of vinyl alcohol and Monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids, preferably 3 to 6 carbon atoms, such as, in particular, acrylic acid , Methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, methyl, ethyl, n-butyl, acrylic acid and methacrylic acid, isobutyl and -2-ethylhexyl ester, maleic acid dimethyl ester or maleic acid di-n-butyl ester, nitriles α, β-monoethylenei sch of unsaturated carboxylic acids such as acrylonitrile, and C_ ₈ conjugated dienes, such as 1,3-butadiene and isoprene. The monomers mentioned generally form the main monomers which, based on the total amount of the monomers to be polymerized by the free-radical aqueous emulsion polymerization process according to the invention, normally comprise a proportion of more than 50% by weight. As a rule, these monomers have only moderate to low solubility in water under normal conditions (25 ° C., 1 bar).

Monomers which have an increased water solubility under the abovementioned conditions are, for example, α, β-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, such as e.g. Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, also vinyl sulfonic acid and its water-soluble salts and N-vinyl pyrrolidone.

In the normal case, the abovementioned monomers are only used as modifying monomers in amounts, based on the total amount of the monomers to be polymerized, of less than 50% by weight, generally 0.5 to 20% by weight, preferably 1 to 10% by weight. -% polymerized.

Monomers which usually increase the internal strength of the films of the aqueous polymer dispersions normally have at least one epoxy, hydroxyl, N-methylol or carbonyl group, or at least two non-conjugated groups ethylenically unsaturated double bonds. Examples of these are N-alkylolamides of α, β-monoethylenically unsaturated carboxylic acids having 3 to 10 C atoms, among which the N-methylolacrylamide and the N-methylolmethacrylamide are very particularly preferred and their esters having 1 to 4 C atoms Alkanols. In addition, two monomers having vinyl radicals, two monomers having vinylidene radicals and two monomers having alkenyl radicals are also suitable. The di-esters of dihydric alcohols with α, β-mono-ethylenically unsaturated monocarboxylic acids, among which acrylic and methacrylic acid are preferred, are particularly advantageous. Examples of such monomers having two non-conjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1, 2-propylene glycol diacrylate, 1, 3-propylene glycol diacrylate, 1, 3-butylene glycol diacrylate and 1, 4-methylene diacrylate -Propylene glycol dimethacrylate, 1, 3-propylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1, 4-butylene glycol dimethacrylate as well as divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allylacrylate, diallymalate, diallyl bis-acrylate, diallyl bis-acrylate, diallyl bis-acrylate or diallyl bis-acrylate. Of particular importance in this context are the methacrylic acid and acrylic acid-Ci-Cg-hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate as well as compounds such as diacetone acrylamide and acetylacet - oxyethyl acrylate and . methacrylate. In the case of aqueous polymer dispersions produced exclusively by the free-radical aqueous emulsion polymerization method, the above-mentioned monomers, based on the total amount of the monomers to be polymerized, are generally copolymerized in amounts of from 0.5 to 10% by weight.

The molar ratio of the ethylenically unsaturated monomers used for the radical aqueous emulsion polymerization according to the invention to the at least one organometallic compound which contains the structural feature of the general formula I is generally> 1, in the normal case> 10, often> 100 and frequently> 1000.

Suitable radical polymerization initiators for the radical aqueous emulsion polymerization according to the invention are all those which are capable of initiating a radical aqueous emulsion polymerization without deactivating the at least one organometallic compound which contains the structural feature I. In principle, these can be both peroxides and azo compounds. Of course, redox initiator systems are also used. dress. In order to conduct the free radical aqueous emulsion polymerization particularly efficiently from the point of view of the desired properties and in terms of high economic efficiency, the use of aliphatic azo compounds, such as, for example, azobisisobutyronitrile, as the radical starter is preferred. The amount of the radical polymerization initiator used is preferably 0.1 to 2% by weight, based on the total amount of the monomers to be polymerized.

The manner in which the free-radical polymerization initiator is added to the polymerization vessel in the course of the free-radical aqueous emulsion polymerization according to the invention is of minor importance. The polymerization initiator can either be completely introduced into the polymerization vessel or, depending on its consumption, can be added continuously or in stages in the course of the free-radical aqueous emulsion polymerization. In particular, this depends in a manner known per se to the person skilled in the art, inter alia on the chemical nature of the polymerization initiator, the monomer system to be polymerized and the polymerization temperature.

A direct consequence of the aforementioned fact is that the reaction temperature for the free radical aqueous emulsion polymerization according to the invention is the entire range from 0 to 150 ° C., temperatures from 70 to 120 ° C., preferably 80 to 100 ° C. and particularly preferably> 85 to 100 ° C, however, are preferably used. The free radical aqueous emulsion polymerization according to the invention can be carried out at a pressure of less than, equal to or greater than 1 bar (absolute), so that the polymerization temperature can exceed 100 ° C. and be up to 150 ° C. Volatile monomers such as ethylene, butadiene or vinyl chloride are preferably polymerized under elevated pressure. The pressure can be 1.2, 1.5, 2, 5, 10, 15 bar or even higher. If emulsion polymerizations are carried out under reduced pressure, pressures of 950 mbar, often 900 mbar and often 850 mbar (absolute) are set. The free radical aqueous emulsion polymerization is advantageously carried out at 1 bar (absolute) under an inert gas atmosphere, such as, for example, under nitrogen or argon.

Instead of or in addition to the radical polymerization initiators mentioned above, at least one compound of the general formula III can advantageously also be used as radical polymerization initiator according to the invention: _R 18 c _χ (III),

R19

With :

X = an element from the group comprising -Cl, -Br, -J, -OR ²⁰ , with R ²⁰ equal to Ci- to C ₂ o -alkyl, in which up to a third of the H atoms independently of one another by -Cl, -Br and -J can be replaced, -SR ²¹ , -SeR ²¹ , -OC (= 0) R ²¹ , -OP (= 0) R ²¹ , -OP (= 0) (ORl) ₂ , -OP (= 0) ORl, -0N (R21) ₂ , -SC (= S) N (R ¹ ) ₂ , -SC (= S) R ²¹ , with R ²¹ equal to -aryl or Ci- to C ₂ o-alkyl and im In the case of -ON (R ²¹ ) _2, the two groups R ²¹ with the N atom carrying them optionally form a 5- or 6-membered heterocyclic ring, and

R ¹⁷ , R ¹⁸ , R ¹⁹ = independently of one another -H, -Cl, -Br, -J, -C0 ₂ H, -CN, -C0 ₂ R ²¹ , Ci to C ₂ o-alkyl, which may be substituted can, C ₃ - to Cβ-cycloalkyl, which may be optionally substituted, -aryl, which may be optionally substituted, -aralkyl, which may optionally be substituted, or heterocyclyl, which may optionally be substituted.

If compounds of the general formula III are used as radical polymerization initiators, compounds with X equal -Cl, -Br and -J are preferred.

The molar ratio of the at least one organometallic compound which contains the structural feature of the general formula I to the at least one radical polymerization initiator depends, inter alia, on the ethylenically unsaturated monomers which are used for aqueous emulsion polymerization, the size and the geometry of the reaction container and whether a partial or the total amount of the ethylenically unsaturated monomers is placed in the aqueous reaction medium and the remaining amount is fed continuously or discontinuously to the aqueous emulsion medium depending on the consumption, which radical polymerization initiator and which metal-organic compound which have the structural feature of the general formula I contains, is used or whether part or all of the at least one organometallic compound in the submitted aqueous reaction medium and the remaining amount is fed continuously or batchwise in the course of the polymerization. A favorable molar ratio of the at least one organometallic compound, which contains the structural feature of the general formula I, to the at least one radical polymerization initiator can be quickly determined by the person skilled in the art for the respective system in easy-to-carry out preliminary tests; it is usually in the range from 0.00001 to 1 to 10 to 1, frequently in the range from 0.001 to 1 to 1 to 1 and often in the range from 0.05 to 1 to 0.5 to 1. Only radical polymerization initiators of the general type are used If formula III is used, the at least one organometallic compound which contains the structural feature of the general formula I can be used in molar deficiency for the free radical aqueous emulsion polymerization.

Usually, in the context of the radical aqueous emulsion polymerization according to the invention, dispersants are used which keep both the monomer droplets and polymer particles dispersed in the aqueous phase and thus ensure the stability of the aqueous polymer dispersion produced. Both the protective colloids usually used to carry out free-radical aqueous emulsion polymerizations and emulsifiers come into consideration as such.

Suitable protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or copolymers containing vinyl pyrrolidone. A detailed description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme-Verlag, Stuttgart, 1961, pages 411 to 420. Of course, mixtures of emulsifiers and / or protective colloids are used. Preferably only emulsifiers are used as dispersants, the relative molecular weights of which, in contrast to the protective colloids, are usually below 1000. They can be anionic, cationic or nonionic in nature. Of course, if mixtures of surface-active substances are used, the individual components must be compatible with one another, which can be checked with a few preliminary tests if in doubt. In general, anionic emulsifiers are compatible with one another and with nonionic emulsifiers. The same applies to cationic emulsifiers, while anionic and cationic emulsifiers are usually not compatible with one another. Common emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 50, alkyl radical: C to Cι), ethoxylated fatty alcohols (EO grade: 3 to 50; Alkyl radical: C ₈ to C ₃₆ ) and alkali metal and ammonium salts of alkyl sulfates (alkyl radical: C ₈ to Cι), of sulfuric acid semiesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl radical: Cι to Ciβ) and ethoxylated alkylphenols (EO degree : 3 to 50, alkyl radical: C ₄ to Cι), of alkyl sulfonic acids (alkyl radical: Cι to Cι ₈ ) and of alkylarylsulfonic acids (alkyl radical: C ₉ to Cι ₈ ). Further suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme-Verlag, Stuttgart, 1961, pages 192 to 208.

Also suitable as surface-active substances are compounds of the general formula IV,

wherein R ²² and R ^{23 are} H atoms or C - to C alkyl and are not simultaneously H atoms, and A and B can be alkali metal ions and / or ammonium ions. In the general formula IV, R ²² and R ^{23 are} preferably linear or branched alkyl radicals having 6 to 18 carbon atoms, in particular having 6, 12 and 16 carbon atoms or -H, where R ²² and R ^{23 are} not both H atoms at the same time are. A and B are preferably sodium, potassium or ammonium, with sodium being particularly preferred. Compounds IV in which A and B are sodium, R ^{22 is} a branched alkyl radical having 12 C atoms and R ^{23 is} an H atom or R ²² are particularly advantageous. Industrial mixtures are used which have a share of 50 to 90 wt .-% of the monoalkylated product, for example Dowfax ^® 2A1 (trademark of Dow Chemical Company). In the process according to the invention, the compounds IV are preferably used on their own and particularly preferably in a mixture with ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl radical: C ₈ to C ₃₆ )

Dispersant used. Compounds IV are well known, e.g. from US-A 4,269,749, and commercially available. As a rule, the amount of dispersant used is 1 to 3% by weight, based on the monomers to be polymerized by free radicals.

Of course, the aforementioned dispersants are generally suitable for carrying out the process according to the invention. However, the process according to the invention also comprises the preparation of aqueous polymer dispersions of self-emulsifying polymers in which monomers which have ionic groups cause stabilization due to the repulsion of charges of the same sign.

Anionic dispersants are preferably used for the process according to the invention.

In the free radical aqueous emulsion polymerization process according to the invention, the controlling effect is achieved in that in the free radical aqueous emulsion polymerization the monomers are polymerized in the presence of at least one organometallic compound which contains the structural feature shown in general formula I. A good controlling effect of the at least one organometallic compound is evident from the fact that, as the degree of polymerization progresses, the number-average molecular weight (M _n ) of the polymer formed from the at least one monomer having at least one ethylenically unsaturated group, linearly with the monomer conversion (U) increases and the straight line shown in a diagram, formed from M _n (ordinate) and given U (abscissa), runs through the coordinate origin (M _n and U equals 0) and the polymer formed also has a small polydispersity value, formed from the quotient of the weight average molecular weight (M _w ) and M _n .

Compounds of the general formula II are used as suitable at least one organometallic compound containing the structural feature of the general formula I,

With:

R ¹ , R ² , R ³ , R ⁴ = independently of one another -H, -CO ₂ M ¹ , with M ¹ equal to -H, alkali metal, ammonium or - (CH ₂ CH ₂ θ-) _m M ² , with M ² equal to -H, alkali metal or ammonium and m is 1 to 1000, -PO- ₃ HM ¹ , -P0 ₃ M ³ M ⁴ , with M ³ and M ⁴ independently of one another the same alkali metal or ammonium, Ci- to Cι ₂ alkyl or substituted alkyl, in which up to four H. Atoms of the alkyl radical are replaced by -OM ¹ , -SM ¹ , -C0M ¹ -NH ₂ , a quartered nitrogen atom, -S0M ** - and / or -OSO- ₃ M ¹ , or -CH ₂ 0 - (CH2CH ₂ θ-) mM ² , also

R ¹ and / or R ^{3 can be} independent of R ² and R ⁴ -CN, and

R ² and R ⁴ together with the C atoms that carry them and are directly connected by a covalent bond, independently of R ¹ and R ^{3, form} an aliphatically saturated, an aliphatically partially unsaturated or an aromatically saturated ring, which can additionally form 1 to 3 Heteroatoms, selected from the group comprising N, 0, S and P, may contain, wherein the number of ring atoms is 5 to 10, and

R ⁵ , R ⁶ , R ⁷ , R ⁸ = independently of one another -H, -F, -Cl, -Br, -J,

-N0 ₂ , -CHO, -SM ¹ , -OM ¹ , -SO-jM ¹ , -CO ₂ M ¹ , -CN, -SCN, -P0 ₃ HMl, -P0 ₃ M ³ M ⁴ , -OSO- ₃ M ¹ , -OP0 ₃ HM ---, -OP0 ₃ M ³ M ⁴ , -NR ¹⁰ R ^{1: L} , with R ¹⁰ and R ¹¹ independently of one another the same -H or Cι ~ to C ₆ alkyl, -SiR ¹² R ¹³ R ¹⁴ , with R ¹² , R ¹³ and R ^14, independently of one another, are the same as Ci- to C ₆ -alkyl or Q -.- to C ₆ -alkoxy, -OR ¹⁵ , -SR ¹⁵ , -C0 ₂ R ¹⁵ , - P0 ₃ HR ¹⁵ , -P0 ₃ R ¹⁵ R ¹⁶ , with R ¹⁵ and R ¹⁶ independently of one another the same as Ci- to C ₃ -alkyl as well

C - to C _δ alkyl, in which up to four H atoms of the alkyl radical by -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -SO-jM ¹ and / or - OS0 ₃ Mi are replaced, -CH ₂ 0- (CH ₂ CH ₂ 0-) _m M ² , Ci- to Cιo ~ alkyl, in which at least half of the C-

Atoms are replaced by at least one substituent from the group comprising -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -SO- ₃ M ¹ and -OS0 ₃ M ** -, C - to Cio-alkenyl, in which up to three H atoms by -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -SO- ₃ M ¹ and / or -OSO- ₃ M ^{1 are} replaced, moreover

two of the radicals R ⁵ , R ⁶ , R ⁷ and R ⁸ , which are carried by neighboring C atoms, together with the C atoms carrying them and, independently of the other radicals, one aliphatically saturated, one aliphatic partially unsaturated or can form an aromatically saturated ring which may additionally contain 1 to 3 heteroatoms selected from the group comprising N, 0, S and P, the number of ring atoms being 5 or 6, and

the two radicals R ⁷ and / or the two radicals R ⁸ , each with the C atoms bearing these radicals, are bridging a 5- or 6-atom covalent

Can form a chain, whereby the atoms bound to the links of the chain are not counted,

R ⁹ = -H,

-.-.- = either a covalent bond or a covalent, bridging chain of up to three atoms, the atoms bound to the links of the chain not being counted,

Me = metal ion,

L = Lewis base and

p = 0, 1 or 2.

Preferred organometallic compounds of the general formula II are those in which the C atoms carrying the radicals R ¹ and R ² and R ³ and R ^{4 are} directly connected to one another via a covalent bond and the radicals R ¹ to R ^{4 are} either H atoms or are part of an optionally substituted benzene ring. Particularly preferred organometallic compounds of the general formula II are those in which at least one of the radicals R ⁵ to R ^{8 is also} an OH group. Particularly preferred organometallic compounds of the general formula II are those in which R ^{7 is} an OH group. In particular, those organometallic compounds of the general formula II are preferred in which the C atoms carrying the radicals R ¹ and R ² and R ³ and R ^{4 are} directly connected to one another via a covalent bond, the radicals R ¹ to R ^{4 are} either H Atoms or with the C atoms carrying them are part of a benzene ring, R ^{7 is} an OH group and the radicals R ⁵ , R ⁶ and R ^{8 are} H atoms. The organometallic compound in which R ¹ to R ^{4 are} H atoms is referred to as the "hydroxysalen complex". If R ¹ to R ^4, on the other hand, are part of a benzene ring with the C atoms carrying them, the organometallic compound is called "hydroxysaloph complex". If R ^{7 is} also an H atom in both cases, one speaks of "Sälen" or "Saloph complexes".

Me is preferably a metal ion that can reversibly occur in at least two oxidation states. Me is advantageous from the group comprising Fe ²⁺ , Fe ³⁺ , Ru ²⁺ , Ru ³⁺ , Cr ²⁺ , Cr ³⁺ , Mo ²⁺ , Mo ³⁺ , W ²⁺ , W ³⁺ , Co ²⁺ , Co ³⁺ , Re ²⁺ , Re ³⁺ , V ²⁺ , V ³⁺ , Mn ²⁺ , Mn ³⁺ , Zr ²⁺ , Zr ³⁺ , Zr ⁴⁺ , Ti ²⁺ , Ti ³⁺ , Ti ⁴⁺ , Ce ²⁺ and Ce ³⁺ selected. The metal ion is often selected from the group comprising Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Cr ²⁺ and Cr ³⁺ . The metal ion with the lower oxidation state is often used.

Suitable Lewis bases L are, for example, water, tetrahydrofuran, dioxane, pyridine, ammonia, primary, secondary or tertiary aliphatic or aromatic amines, the aliphatic or aromatic radicals of which may be optionally substituted, and optionally substituted trialkyl, trialkoxy, triaryl and triaryloxyphosphines. Depending on the metal ion Me, the radicals R ¹ to R ⁸ and the conditions during the free radical aqueous emulsion polymerization, the number p of the coordinated Lewis bases L can be 0, 1 or 2.

The syntheses of the organometallic compounds of the general formula II have been described many times before and are therefore sufficiently known to the person skilled in the art [cf. see the patents EP-A 362 139 and JP 1 090 150 and Yang et al. in Hecheng Huaxue 1995, 3 (1), pages 75 ff., Kasuaga et al. in Inorg. Chem. Acta 1989, 157, pages 267 ff., Spiratos et al. in Rev. Roum. Chim. 1980, 25, pages 1083 ff., Spiratos et al. in Rev. Roum. Chim. 1984, 29, pages 457 ff., Fullerton and Ahern in Tetrahedron Lett. 1976, pages 139 ff., Zelentsov and Somova in Zh. Obshch. Khim. 1974, 44 (6), pages 1309 ff., Vitalini et al. in Macromolecules 1996, 29, pages 4478 ff., Gaber et al. in Egypt. J. Chem. 1992, 34, pages 107 ff., Kanbayashi et al. in J. Chromatogr. 1987, 386, pages 191 ff., Marcu et al. in polym. Bull. 1986, 16 (2-3), pages 103 ff., Dorutiu et al. in Stud. Univ. Babes-Bolyai, [Ser.] Chem. 1980, 25 (2), pages 49 ff., Zelentsov and Somova in Zh. Neorg. Khim. 1973, 18 (8) pages 2128 ff. As well as Mukherjee and Ray in J. Indian Chem. Soc. 1955, pages 604, 606 and 607]. Usually - an aromatic hydroxycarbonyl compound of the general formula V is reacted with a diamine of the general formula VI according to the following reaction scheme to give a Schiff's base reaction product of the general formula VII, which in turn is virtually quantitatively the metal-organic compound of the general formula with the metal ion Formula II forms:

R ⁷ R ⁷

(V) (V)

(VII)

Organometallic compounds of the general formula II are to a certain extent soluble in water and in organic solvents and in olefinically unsaturated monomers for which styrene is a representative representative at a pressure of 1 bar (absolute) and a temperature of 20 ° C. Their solubility in water can be significantly influenced by adding bases or acids. According to the invention, the use of organometallic compounds of the general formula II is claimed, the solubility of which is greater under the above-mentioned conditions either in 1000 g of acidic, basic and / or neutral water than its solubility in 1000 g of styrene. In this document, solubility means the maximum amount of dissolved organometallic compound of the general formula II in grams per 1000 g of solvent. UV / VIS spectroscopic methods are particularly suitable for determining the solubility of these metal-organic compounds.

Organometallic compounds suitable according to the invention which contain the structural feature of the general formula I generally have a solubility of <100 g / at a pressure of 1 bar (absolute) and a temperature of 20 ° C. in acidic, basic and / or neutral water. 1000 g, but often a solubility

> 0.001 g / 1000 g and often> 0.1 g / 1000 g. In styrene, the organometallic compounds mentioned have identical ones Conditions usually a solubility <1 g / 1000 g, often

<0.1 g / 1000 g and often <0.01 g / 1000 g.

The process according to the invention can be carried out, for example, in such a way that either a partial or total amount of the water required, the at least one required, the organometallic compound containing the structural feature of the general formula I, the at least one polymerization initiator, the optionally at least one emulsifier, the optionally ver - submitted at least one protective colloid and / or the at least one monomer having at least one ethylenically unsaturated group and any other usual auxiliaries and additives in a reaction vessel and the contents of the reaction vessel are heated to the reaction temperature. At this temperature, the remaining amounts of water, the at least one organometallic compound containing the structural feature of the general formula I, the at least one polymerization initiator, the optionally at least one emulsifier, the optionally used at least one protective colloid and / or or of the at least one monomer having at least one ethylenically unsaturated group and any further customary auxiliaries and additives which are added continuously or discontinuously and then optionally kept further at the reaction temperature.

However, the process according to the invention can also be carried out in such a way that either part or all of the water required, the optionally at least one emulsifier, the optionally used at least one protective colloid and / or the at least one monomer having at least one ethylenically unsaturated group and the optionally further customary auxiliaries and additives and, if appropriate, a subset of the at least one organometallic compound containing the structural feature of the general formula I and the at least one polymerization initiator are placed in a reaction vessel and the contents of the reaction vessel are heated to the reaction temperature. At this temperature, the total or any remaining amount of the at least one organometallic compound containing the structural feature of the general formula I and the at least one polymerization initiator, and any remaining amounts of water, optionally at least one emulsifier, and optionally used at least one protective colloid and / or the at least one monomer having at least one ethylenically unsaturated group and any other customary auxiliaries and additives added nuously or discontinuously and then optionally kept at the reaction temperature.

It is also possible to use a polymer seed in part or all of the amount of water required, the at least one organometallic compound containing the structural feature of the general formula I, the at least one polymerization initiator, the optionally at least one emulsifier, or the one used where appropriate to present at least one protective colloid and / or any further customary auxiliaries and additives at reaction temperature in a reaction container. The total amount of the at least one monomer having at least one ethylenically unsaturated group and any remaining amounts of water, the at least one organometallic compound containing the structural feature of the general formula I, the at least one polymerization initiator and, if appropriate, at least one emulsifier, the optionally used at least one protective colloid and / or the optionally further customary auxiliaries and additives are added to the reaction mixture present in the reaction vessel at the reaction temperature with stirring continuously or discontinuously and then optionally kept at the reaction temperature.

In this so-called seed procedure, it is also possible, if appropriate, to introduce a partial amount of the at least one organometallic compound containing the structural feature of the general formula I and the at least one polymerization initiator into the reaction vessel and, at the reaction temperature, the total or the remaining amount of the at least one, the structural feature of the general formula I-containing metal-organic compound and the at least one polymerization initiator and the total amount of the at least one monomer having at least one ethylenically unsaturated group and any remaining amounts of water, optionally at least one emulsifier, of the at least one optionally used a protective colloid and / or the further customary auxiliaries and additives, if appropriate, are added continuously or discontinuously with stirring.

In addition to or instead of the at least one organometallic compound containing the structural feature of the general formula I, at least one organometallic compound of the general formula VIII can also be used in the abovementioned procedures.

15 wherein Z is an aryl group or a Ci- to -C ₂ alkyl group and L and p have the meanings given above.

Organometallic compounds of the general formula VIII differ from organometallic compounds of the general

20 Formula II only in that the metal ion is additionally connected to an alkyl or aryl group. The bond between the metal ion and the alkyl or aryl group is thermally labile. At temperatures as are usual in the radical aqueous emulsion polymerization according to the invention (in a typical manner

25 70 to 120 ° C), the bond between the metal ion and the alkyl or aryl group is thermally split and the metal - organic compound of general formula II is formed in situ according to the following reaction scheme:

(VIIi;

45 Organometallic compounds of the general formula VIII can be obtained in a simple manner from the corresponding halides of the general formula IX by reaction with a Grignard reagent or an alkyl or aryllithium compound according to the following reaction scheme:

(IX)

wherein Hai -Cl, -Br or -J and Z is an aryl group or a C ~ to Ci ₂ alkyl group and L and p have the meanings given above.

According to the invention, it is essential that the method according to the invention is advantageously suitable for the production of aqueous polymer dispersions of block polymers. This is possible in a simple manner that first one

Polymerized monomer type and then continues the polymerization with another monomer type. Polyblocks can also be generated by further monomer changes.

Of course, the residual monomers remaining in the aqueous polymer dispersion after completion of the main polymerization reaction can be stripped by steam and / or inert gas and / or by chemical deodorization, as described, for example, in documents DE-A 4 419 518, EP-A 767 180 or DE-A 3 834 734 are removed without the polymer properties of the aqueous polymer dispersion being adversely affected. It is also important that the organometallic compounds according to the invention, which have the structural feature of the general formula I, generally do not reduce the effectiveness of the microbioids to be added to the aqueous polymer dispersions as preservatives. The at least one organometallic compound which has the structural feature of the general formula I can also be removed from the aqueous polymer dispersion obtainable according to the invention if necessary. For example, the disperse polymer can be separated from the aqueous serum by centrifugation, by adding neutral, acidic and / or basic. Redisperse water, centrifuge again, etc., the at least one organometallic compound accumulating in the serum.

Alternatively, the at least one organometallic compound which has the structural feature of the general formula I can also be separated from the aqueous polymer dispersion according to the invention by coagulation and repeated washing of the coagulated polymer with neutral, acidic and / or basic water.

Aqueous polymer dispersions which contain at least one metal-organic compound which has the structural feature of the general formula I or which are prepared by the process according to the invention described are particularly suitable for the production of adhesives, for example pressure-sensitive adhesives, construction adhesives or industrial adhesives, Binders, such as for paper coating, dispersion paints or for printing inks and varnishes for printing on plastic films, for the production of nonwovens and for the production of protective layers and water vapor barriers, such as for example in the primer.

Examples

General determination of the solubility of organometallic compounds of the general formula II by UV / VIS spectroscopy.

At 20.degree. C. and 1 bar (absolute), as much as possible of the organometallic compound of the general formula II was added to water, which contained 0.5% by weight of sodium carbonate [Na ₂ CO ₃ ] and to styrene until it was added the organometallic compound were saturated. The organometallic compound that was not dissolved was filtered off through a 0.2 μm filter.

For each organometallic compound investigated, 4 calibration solutions in water and in styrene were also prepared under the conditions mentioned above, their concentrations (grams of dissolved organometallic compound per 1000 g Water or styrene) were below the respective solubilities and which were exactly known.

The respective UV / VIS absorptions could be measured by UV / VIS absorption measurements of the solutions 5 produced in this way with a UVIKON spectrometer 922, and the respective solubilities could be determined from this using the Beer-Lambert law.

The solubilities of the following organometallic compounds of general formula II were determined by way of example:

Organometallic solvents Solubility Binding of the general 20 ° C, 1 bar (absoin g per 1000 g

Formula II (solvent)

15 Connection 1

R ¹ to R ⁸ are -H, water <0.005, the C atoms carrying the radicals R ¹ to R ⁴ are styrene 0.403 directly via a covalent bond with

20 linked to each other, Me is Co ²⁺ and p is 0 ("Salen-Cobalt")

Connection 2

25

Analogous to compound 1, water 0.630, but R ⁷ is -OH

("Hydroxysalen Cobalt") styrene <0.005

30 connection 3

R ⁵ to R ⁸ are -H, water <0.005, the radicals R ¹ to R ⁴ together with the styrene 0.958 are C atoms

Part of a Ben¬

35 zolrings, Me is Co ²⁺ and p is 0 ("Saloph cobalt")

Connection 4

40 Analog connection 3, water 0.340

^ \ J but R ⁷ is -OH;

("Hydroxysaloph-co-styrene <0.005 balt")

45 Carrying out the controlled radical emulsion polymerizations

1st example

In a 250 ml three-necked flask (analogous to Article No. 614010 from Kimble Glass Inc., 537 Crystal Avenue, Vineland, New Jersey 08360, USA), equipped with a reflux condenser and a mechanical stirrer, were placed under an argon atmosphere at 20 ° C. and 1 bar (absolute) 110 g of deionized and oxygen-free water, 0.5 g of sodium dodecyl sulfate, 0.2 g of sodium carbonate and 44 mg of N, N'-bis (2,4-dihydroxybenzylidene) -1, 2-diaminobenzene (hydroxysalophane; compound of the general formula VII, where the radicals R ¹ to R ⁴ together with the carbon atoms carrying them form part of a benzene ring, R ⁵ , R ⁶ , R ⁸ and R ^{9 are} H atoms and R ^{7 is} an OH group is) submitted with stirring. To this solution was first added, with stirring, a solution prepared from 3 g of deionized, oxygen-free water and 36 mg of cobalt (II) acetate tetrahydrate [Co (OAc) ₂ × 4 H ₂ O] and then a solution prepared from 180 mg iodoform [HCJ ₃ ] and 10.3 g oxygen-free styrene. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. The styrene conversions then determined as a function of time and the number-average molecular weights of the polymers formed are given in Table 1. A graphic representation of the number average molecular weights as a function of the styrene conversion is shown in FIG. 1. The polymers formed after 330 minutes with a styrene conversion of 36.8% by weight had a polydispersity index of 2.7 and a weight-average particle diameter of 618 nm.

Table 1: Dependence of the styrene conversion (U) and the number-average molecular weights (M _n ) of the polymers formed on the time (t) t U in minutes in% by weight in g / mol

60 17.1 730

200 28.3 1650

330 36.8 2300 The monomer conversion was generally determined using the following formula:

Monomer conversion (t) =

Dry residue (t) - Dry residue (t = 0) Dry residue (t = ∞) - Dry residue (t = 0)

With

Dry residue (t equal to the dry residue obtained from an aliquot of the reaction mixture taken at the time when the reaction mixture just reached the reaction temperature, calculated back to the total mixture,

Dry residue (t) is the dry residue obtained from an aliquot of the reaction mixture, which was taken from the reaction mixture at time t, calculated back to the total mixture,

Dry residue (t = ∞): equal to the dry residue that would be obtained if the monomer were 100% polymerized. This dry residue is calculated by adding the total amount of monomers to the dry residue (t = 0).

The dry residue was generally determined by drying the respective aliquot sample at 60 ° C. and 1 mbar to constant weight.

5 The respective number average molecular weight (M _n ) and the polydispersity indices (M _w / M _n ) of the polymers were determined by gel permeation chromatography. For this purpose, the dry residue obtained was taken up in a little tetrahydrofuran, passed at 45 ° C using a Waters 600 high-pressure pump over 10 KF-803L and two KF-805L Shodex columns connected in series and over Waters 410 refractometer or Waters 996 photodiodes Detectors analyzed. The evaluation was carried out using a millennium software.

The weight-average particle diameters were generally determined using the light scattering method using AutoSizer Lo-C from Malvern Instruments Ltd. certainly.

2nd example

20 122 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute) , 1.6 g sodium dodecyl sulfate, 0.3 g sodium carbonate and

25 62 mg of hydroxysalophone are added with stirring. To this solution was first added, with stirring, a solution made from 3 g of deionized, oxygen-free water and 42 mg of cobalt (II) acetate tetrahydrate and then a solution made from 400 mg of iodoform and 19.8 g of oxygen-free styrene . The aqueous emulsion formed

30 sion was heated to the reaction temperature of 95 ° C. in the absence of light within 11 minutes. The styrene conversions then determined as a function of time and the number-average molecular weights of the polymers formed are given in Table 2. A graphical representation of the number average molecular

35 weights of the polymers formed depending on the styrene conversion is shown in Figure 2. The polymers formed after 720 minutes with a styrene conversion of 76.5% by weight had a polydispersity index of 1.6 and a weight-average particle diameter of 102 nm.

40

45 Table 2: Dependence of the styrene conversion (U) and the number average molecular weights (M _n ) of the polymers formed on the time (t)

t UM _n in minutes in wt. -% in g / mol

15 8.8 700 0 55 12.5 900

95 15.2 1000

210 38.5 2850

320 53.8 4250

720 76.5 4800 5

3rd example

121 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from 0 Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute) , 1.7 g of sodium dodecyl sulfate, 0.3 g of sodium carbonate and 62 mg of hydroxysalophone with stirring. To this solution was first added, with stirring, a solution made from 3 g of deionized, oxygen-free water and 42 mg of cobalt (II) acetate tetrahydrate and then a solution made from 400 mg of iodoform and 11.7 g of oxygen-free Methyl methacrylate (MMA). The aqueous emulsion formed was heated to the reaction temperature of 80 ° C. in the absence of light within 11 minutes. The MMA conversions then determined as a function of time and the number-average molecular weights of the polymers formed

5

0

5 given in Table 3. A graphic representation of the number average molecular weights of the polymers formed as a function of the MMA conversion is shown in FIG. 3. The polymers formed after 5 355 minutes with an MMA conversion of 92.8% by weight had a polydispersity index of 2.1 and a weight-average particle diameter of 77 nm.

Table 3: Dependence of the MMA conversion (U) and the number-average molecular weights (M _n ) of the polymers formed on the time (t) t UM _n in minutes in% by weight in g / mol

105 67.2 8500 5 180 83.5 11600 355 92.8 12700

0 4th example

158 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 5 bar (absolute) , 1.0 g of sodium dodecyl sulfate, 0.3 g of sodium carbonate and 52 mg of hydroxysalophone with stirring. A solution, prepared from 3 g of deionized, oxygen-free water and 42 mg of cobalt (II) acetate tetrahydrate, and then a solution, prepared from 270 mg of 1-iodoethyl acetate and 12, were first added to this solution with stirring , 7 g of oxygen-free MMA. The aqueous emulsion formed was heated in the absence of light within 11 minutes.

5

0

5 grooved to a reaction temperature of 80 ° C. The MMA conversions then determined as a function of time and the number-average molecular weights of the polymers formed are given in Table 4. A graphic representation of the number average molecular weights of the polymers formed as a function of the MMA conversion is shown in FIG. 4. The polymers obtained after 60 minutes with an MMA conversion of 25.2% by weight had a polydispersity index of 1.8.

Table 4: Dependence of the MMA conversion (U) and the number average molecular weights (M _n ) of the polymers formed on the time (t) t UM _n in minutes in wt in g / mol

10 14, 3 21100

25 21, 7 26000

60 25, 2 33300

5th example

160 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute). 1.0 g of sodium dodecyl sulfate, 0.1 g of sodium carbonate and 94 mg of hydroxysalophone are introduced with stirring. To this solution was first added, with stirring, a solution prepared from 3 g of deionized, oxygen-free water and 65 mg of trichrome dihydroxyheptacetate [Cr ₃ (OH) ₂ (OAc)] and then a solution prepared from 400 mg of iodoform and 12.0 g Oxygen-free MMA. The educated

aqueous emulsion was heated to the reaction temperature of 80 ° C. in the absence of light within 11 minutes. The MMA conversions determined as a function of time and the number-average molecular weights are given in Table 5. A graphic representation of the number average molecular weights of the polymers formed as a function of the MMA conversion is shown in FIG. 5. The polymers formed after 150 minutes had a polymer dispersity index of 2.4 and a weight-average particle diameter of 150 nm.

Table 5: Dependence of the MMA conversion (U) and the number average molecular weights (M _n ) of the polymers formed on the time (t) t UM _n in minutes in wt. In g / mol

10 22.0 5500

50 40.5 7500

70 44.9 7800

150 52.5 7900

6th example

In a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.), equipped with a reflux condenser and a mechanical stirrer, 128 g of deionized and oxygen-free water were placed under an argon atmosphere at 20 ° C. and 1 bar (absolute). 0.8 sodium dodecyl sulfate, 0.3 g sodium carbonate and 45 mg N, N'-bis (2, 4-dihydroxybenzylidene) -1, 2-diaminoethane (hydroxysalen; compound of the general formula VII, where the radicals R ¹ to R ⁶ as well as R ⁸ and R ^{9 are} H atoms and R ^{7 is} an OH group and the C atoms carrying the radicals R ¹ to R ⁴ directly via a covalent one

Are linked together) submitted with stirring. To this solution was added first a solution made from 3 g of deionized, oxygen-free water and 38 mg of cobalt (II) acetate tetrahydrate, and then a solution made from 300 mg of iodoform and 11.0 g of oxygen-free styrene. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 520 minutes, a monomer conversion of 52% by weight was achieved. The polymers formed had a number average molecular weight of 32000 g / mol, a weight average particle diameter of 267 nm and a polydispersity index of 2.0.

1. Comparative example

15 108 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute) , 1.0 g sodium dodecyl sulfate, 0.3 g sodium carbonate and

20 36 mg of cobalt (II) acetate tetrahydrate are introduced with stirring. To this was added a solution prepared from 12.0 g of oxygen-free styrene, 44 mg of N, N'-bis (2-hydroxybenzylidene) -1, 2-diamine-topzole (Saloph; compound of the general formula VII, the Radicals R ¹ to R ⁴ together with the C atoms carrying them consist

25 are part of a benzene ring and R ⁵ to R ^{9 are} H atoms) and 210 mg iodoform. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 10 minutes the emulsion was completely coagulated. None could be dispersed in the aqueous phase

30 polymer particles can be detected.

2. Comparative example

In a 250 ml three-necked flask (similar to Article No. 614010 from

35 Kimble Glass Inc.), equipped with a reflux condenser and a mechanical stirrer, 110 g of deionized and oxygen-free water, 0.5 g of sodium dodecyl sulfate, 0.2 g of sodium carbonate and 36 mg were added under an argon atmosphere at 20 ° C. and 1 bar (absolute) Cobalt (II) acetate tetrahydrate submitted with stirring.

40 To this was added a solution prepared from 12.5 g of oxygen-free styrene, 44 mg of N, N'-bis (2-hydroxybenzylidene) -1, 2-diaminoethane (columns; compound of the general formula VII, where the radicals R ¹ to R ^{9 are} H atoms and the C atoms carrying the radicals R ¹ to R ^{4 are} directly connected to one another via a covalent bond

45) and 180 mg of 1-bromoethylbenzene. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 10 minutes the emul sion completely coagulated. No dispersed polymer particles could be detected in the aqueous phase.

3. Comparative example

In a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.), equipped with a reflux condenser and a mechanical stirrer, 110 g of deionized and oxygen-free water were placed under an argon atmosphere at 20 ° C. and 1 bar (absolute). 0.5 g of sodium dodecyl sulfate, 0.2 g of sodium carbonate, 36 mg of cobalt (II) acetate tetrahydrate and 44 mg of rooms are introduced with stirring. To this was added a solution made from 12.5 g of oxygen-free styrene and 180 mg of 1-bromoethylbenzene. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 10 minutes the emulsion was completely coagulated. No dispersed polymer particles could be detected in the aqueous phase.

4. Comparative example

122 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute). 0.8 g sodium dodecyl sulfate, 0.6 g sodium carbonate and

36 mg of iron (II) acetate [Fe (OAc) ₂ ] submitted with stirring. To this was added a solution made from 12.0 g of oxygen-free styrene, 46 mg of rooms and 200 mg of iodoform. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 10 minutes the emulsion was completely coagulated. No dispersed polymer particles could be detected in the aqueous phase.

5. Comparative example

144 g of deionized and oxygen-free water were placed in a 250 ml three-necked flask (similar to Article No. 614010 from Kimble Glass Inc.) equipped with a reflux condenser and a mechanical stirrer under an argon atmosphere at 20 ° C. and 1 bar (absolute). 1.2 g of sodium dodecyl sulfate, 0.4 g of sodium carbonate and 35 mg of cobalt (II) acetate tetrahydrate are introduced with stirring. To this was added a solution made from 13.5 g of oxygen-free MMA, 51 mg of columns and 240 mg of 1-bromoethylbenzene. The aqueous emulsion formed was heated to a reaction temperature of 90 ° C. in the absence of light within 11 minutes. After 10 minutes the emulsion was completely coagulated. In the watery Phase, no dispersed polymer particles could be detected.

Claims

claims

Method of free-radically initiated aqueous emulsion polymerization for producing an aqueous polymer dispersion, in which at least one chemical compound (monomer) having at least one ethylenically unsaturated group is dispersed in an aqueous medium and by means of at least one free-radical polymerization initiator in the presence of at least one organometallic compound is polymerized, characterized in that the at least one organometallic compound on the one hand has the following structural feature of the general formula I,

With:

Me • = metal ion,

= a covalent bond to a neighboring atom,

Process according to Claim 1, characterized in that the at least one organometallic compound is a compound of the general formula II,

is with:

R ¹ , R ² , R ³ , R ⁴ = independently of one another -H, -CO ₂ M ¹ , with M ¹ equal to -H, alkali metal, ammonium or - (CH ₂ CH ₂ 0-) _rn M ² , with M ² equal to -H, alkali metal or ammonium and m equal to 1 to 1000, -PO-jHM ¹ , -P0 ₃ M ³ M ⁴ , with M ³ and M ⁴ independently of one another equal to alkali metal or ammonium, Ci to Ci ₂ alkyl or substituted Alkyl in which up to four H atoms of the alkyl radical are replaced by -OM ¹ , -SM ¹ , -C0 ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -SOsM ¹ and / or -OSO- ₃ M ¹ are, or -CH ₂ 0- (CH ₂ CH ₂ 0-) mM ² , furthermore

R ¹ and / or R ^{3 can be} independent of R ² and R ⁴ -CN, and

R ² and R ⁴ together with the carbon atoms carrying them, which are directly connected by a covalent bond, independently of R ¹ and R ^{3, can form} an aliphatically saturated, an aliphatically partially unsaturated or an aromatically saturated ring which additionally contains 1 to 3 heteroatoms, selected from the group comprising N, 0, S and P, where the number of ring atoms is 5 to 10, and

R ⁵ , R ⁶ , R ⁷ , R ⁸ - independently of one another -H, -F, -Cl, -Br, -J, -N0 ₂ , -CHO, -SM ¹ , -OM ¹ , -S0 ₃ M ** -, -CO ₂ M ¹ , -CN, -SCN, -PO- ₃ HM ¹ , -P0 ₃ M ³ M ⁴ , -OS0 ₃ M ** -, -OPOsHM ¹ , -OP0 ₃ M ³ M ⁴ , - NR ^ R ¹¹ , with R ¹⁰ and R ¹¹ independently of one another the same -H or Cι ~ to Cε-alkyl, -SiR ¹² R ¹³ R ¹⁴ , with R ¹² , R ¹³ and R ¹⁴ independently from one another are C ₁ -C ₆ -alkyl or C ₁ -C ₆ -alkoxy, -OR ¹⁵ , -SR ¹⁵ , -C0 ₂ R ¹⁵ , -P0 ₃ HR ¹⁵ , -P0 ₃ R ¹⁵ R ¹⁶ , with R ¹⁵ and R ¹⁶ independently of one another are identical to C ₁ -C ₃ -alkyl and C ₂ - to C ₆ -alkyl, in which up to four H atoms of the

Alkyl radical are replaced by -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -S0 ₃ M ** - and / or -OS0 ₃ M ** -, -CH ₂ 0- ( CH ₂ CH ₂ 0-) _m M ² , Ci- to Cio-alkyl, in which at least half of the C atoms by at least one

Substituents from the group comprising -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -SO- ₃ M ¹ and -OSO- ₃ M ^{1 are} replaced, C ₂ - to Cio-alkenyl , in which up to three H atoms are replaced by -OM ¹ , -SM ¹ , -CO ₂ M ¹ , -NH ₂ , a quaternized nitrogen atom, -S0 ₃ M ** - and / or -OS0M - * -, Moreover

two of the radicals R ⁵ , R ⁶ , R ⁷ and R ⁸ , which are carried by neighboring C atoms, together with the C atoms carrying them and independently of the other radicals, an aliphatically saturated, an aliphatically partially unsaturated or one aromatically saturated ring that can additionally 1 to 3

Heteroatoms, selected from the group comprising N, 0, S and P, may contain, wherein the number of ring atoms is 5 or 6, as well

the two radicals R ⁷ and / or the two radicals

R ⁸ , in each case with the C atoms carrying these residues, can form a 5- or 6-atom covalent, bridging chain, the atoms bound to the links of the chain not being counted,

R ⁹ = -H,

-.-.- = either a covalent bond or an up to three atom covalent, bridging

Chain, whereby the atoms bound to the links of the chain are not counted,

Me = metal ion,

L = Lewis base and p = 0, 1 or

2nd

3. The method according to claim 1 or 2, characterized in that Me can occur reversibly in at least two oxidation levels.

4. The method according to any one of claims 1 to 3, characterized in that Me is selected from the group comprising Fe ²⁺ , Fe ³⁺ , Ru ²⁺ , Ru ³⁺ , Cr ⁺ , Cr ³⁺ , Mo ²⁺ , Mo. ³⁺ , W ⁺ , W ³⁺ , Cθ ²⁺ , Co ³⁺ , Re ⁺ , Re ³⁺ , V ²⁺ , V ⁺ , Mn ²⁺ , Mn ³⁺ , Zr ²⁺ , Zr ³⁺ , Zr ^{4 +} , Ti ²⁺ , Ti ³⁺ , Ti ⁺ , Ce ²⁺ , Ce ³⁺ .

5. The method according to any one of claims 2 to 4, characterized in that L is selected from the group comprising water, tetrahydrofuran, dioxane, pyridine, ammonia, primary

Amines, secondary amines, tertiary amines, trialkyl, trialk oxy, triaryl and triaryloxyphosphine.

6. The method according to any one of claims 1 to 5, characterized in that a part or the total amount of at least one, the structural feature of the general formula I containing organometallic compound is added to the aqueous medium before, with and / or after the monomers .

7. The method according to any one of claims 1 to 5, characterized in that a partial or the total amount of at least one, the structural feature of the general formula I containing organometallic compound in the aqueous medium before, during and / or after the monomer addition in situ- is fathered.

8. The method according to any one of claims 1 to 7, characterized in that as a radical polymerization initiator at least one compound of general formula III,

is used with:

X = an element from the group comprising -Cl, -Br, -J, -OR ²⁰ , with R ²⁰ equal to Cι ~ bis

C ₂ o-alkyl, in which up to one third of the H atoms independently of one another by -Cl, -Br and -J can be replaced, -SR ²¹ , -SeR ²¹ , -OC (= 0) R ²¹ , -OP (= 0) R ²¹ , -OP (= 0) (OR ¹ ) ₂ , -OP (= 0 ) OR ²¹ , -ON (R ²¹ ) ₂ , -SC (= S) N (R2 ¹ ) ₂ -SC (= S) R ²¹ , with R ²¹ equal to aryl or Ci- to C ₂ o-alkyl and im Case of -ON (R ²¹ ) ₂ the two

Groups R ²¹ with the N atom carrying them optionally form a 5- or 6-membered heterocyclic ring, and

R ¹⁷ , R ¹⁸ , R ¹⁹ = independently of one another -H, -Cl, -Br, -J,

-C0 ₂ H, -CN, -C0 ₂ R ²¹ , C _x - to C ₂₀ alkyl, which may optionally be substituted, C ₃ - to C ₈ cycloalkyl, which may optionally be substituted, aryl, which may or may not be substituted - Tuiert, -Aralkyl, which may optionally be substituted or heterocyclyl, which may optionally be substituted.

9. The method according to claim 8, characterized in that X is -Cl, -Br or -J.

10. The method according to any one of claims 1 to 9, characterized in that the molar ratio of the at least one organometallic compound which contains the structural feature of the general formula I to the at least one polymerization initiator is 0.00001 to 1 to 10 to 1.

11. The method according to any one of claims 1 to 10, characterized in that the molar ratio of the monomers to the at least one organometallic compound which the

Structural feature of the general formula I contains> 1.

12. Aqueous polymer dispersion containing at least one organometallic compound which contains the structural feature of the general formula I.

13. Aqueous polymer dispersion obtainable by a process according to one of claims 1 to 11.

14. Use of an aqueous polymer dispersion according to claim 12 or 13 as an adhesive, as a binder or for producing a protective layer.

5. organometallic compound which has the following structural feature of the general formula I,

With

Me = metal ion,

a covalent bond to a neighboring atom.