WO1999001483A1

WO1999001483A1 - Method for producing polyalkyl(meth)acrylates

Info

Publication number: WO1999001483A1
Application number: PCT/EP1998/003835
Authority: WO
Inventors: Stephan JÜNGLING; Hermann Gausepohl; Horst Weiss; Axel H. E. MÜLLER; Helmut Schlaad; Bardo Schmitt
Original assignee: Basf Aktiengesellschaft
Priority date: 1997-07-04
Filing date: 1998-06-23
Publication date: 1999-01-14
Also published as: AU8728498A; DE19728628A1

Abstract

The invention relates to a method for producing homopolymers, copolymers or block copolymers by anionic polymerization of acrylates and/or methacrylates in the presence of an initiator composition containing A) an alkali organic compound, an alkali alkoxide or an alkali amide, B) an organic aluminium compound and C) an alkali or an alkaline earth salt as an alkali cation complexing additive.

Description

Process for the preparation of polyalkyl (meth) acrylates

description

The present invention relates to a process for the preparation of homopolymers, copolymers or block copolymers by anionic Polymeri ^¬ sation of acrylates and / or methacrylates in the presence of an initiator composition comprising

A) an alkali organic compound, an alkali alkoxide or an alkali amide,

B) an organic aluminum compound and

C) an alkali or alkaline earth metal salt as an additive complexing the alkali application.

Furthermore, the present invention relates to the initiator composition and a method for producing the initiator composition and its use.

The anionic and coordinative polymerization of (meth) acrylic acid esters is difficult due to the side reactions associated with the carbonyl group, such as transfer and chain termination reactions, in particular with regard to the control of molecular weight, molecular weight distribution and stereoregularity. Various possibilities for the controlled polymerization of (meth) acrylic acid esters have been described in J.M.S. - Rev. Makromol. Chem. Phys. C34 (2), 243 - 324 (1994) with their advantages and disadvantages discussed in summary.

For example, EP-B-0274318, the anionic Polymeri zation ^¬ described of acrylate monomers with an alkali or Erdalkalialkyl as an initiator in the presence of macrocyclic complexing agents. The process is carried out in tetrahydrofuran at temperatures of -78 ° C. Furthermore, LiCl

(EP-A-0 408 420) or lithium alcoholates are used as complexing additives. However, a narrow molecular weight distribution is only achieved at low temperatures, which causes long polymerization times and technically complex and expensive equipment. In addition, when using tetrahydrofuran as

Due to the formation of peroxides, further safety precautions must be taken.

EP-A-0 434 316 discloses the polymerization of methacrylates by alkali metal alkyls in the presence of organic aluminum compounds with sterically demanding radicals. The However, reaction times are still in the range of several hours, even at higher temperatures.

A widespread problem in the anionic polymerization of acrylates in the presence of alkyl lithium and aluminum alkyl compounds is gel formation, especially in nonpolar solvents. It probably arises from the fact that several molecules (monomers or already formed polymer chains) coordinate to the metal center. This phenomenon means that on the one hand the reaction mixture is difficult to handle, on the other hand the molecular weight distribution of the polyalkylacrylates is broad and frequently complete conversion of the monomers is not achieved.

A metal-free initiation by ammonium salts of resonance-stabilized carbanions is known from EP-A-0 306 714. Tetr - alkylammonium salts tend to Hoffmann elimination in the presence of strong bases, such as uncomplexed carbanions, which leads to chain termination.

The object of the present invention was therefore to develop a new starter composition which allows good control of the polymerization reaction. In particular, a process should be made available which leads to products with a narrow molecular weight distribution even at higher temperatures. It is therefore an object to arrive at "living" anionic polymer chains with increased stability. In addition, sales should be as quantitative as possible and block copolymers should be able to be produced. In addition, the reaction rate should be suitable for technical purposes. In addition, the task was to find a process which is largely insensitive to the impurities present in monomers and technical-grade solvents. Furthermore, a method should be developed in which gel formation is avoided.

Accordingly, a process for the preparation of homo-, co- or block copolymers by anionic polymerization of acrylates and / or methacrylates in the presence of an initiator composition was obtained

A) an alkali organic compound, an alkali alkoxide or an alkali amide,

B) an organic aluminum compound and C) an alkali or alkaline earth salt found as an additive complexing the alkali application. Both homopolymers and copolymers or block copolymers come into consideration as polyalkyl (meth) acrylates. For example, copolymers can be prepared from mixtures of different alkyl acrylates or different alkyl methacrylates or mixtures of alkyl acrylates with alkyl methacrylates. Block copolymers can be obtained, for example, from different alkyl acrylates or different alkyl methacrylates or from alkyl acrylates and alkyl methacrylates. Both two-block copolymers and multi-block copolymers can be prepared by the process according to the invention. Here, the weight reduction of the blocks together ^¬ varied within wide limits.

Under suitable Methacrylatmonomerbausteine fall include alkyl ^¬ methacrylates having 1 to 20 carbon atoms, preferably 1 to 10, in the - particular 1 to 6 carbon atoms in the Esterrest. The ester residue can be either linear or branched. The ester radical can also be a cycloalkyl radical. It is preferably linear. The methacrylates may be stituiert sub ^¬ with one or more halogen atoms. Examples are: methyl methacrylate, ethyl methacrylate, 2, 2, 2, -trifluoroethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, i-pentyl methacrylate acrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, n-decyl methacrylate. It is also possible to use methacrylates with an olefinically unsaturated ester unit, such as dihydrodicyclopentadienyl methacrylate, allyl methacrylate or those with aromatic ester residues, such as phenyl or 2-phenoxyethyl, or with vinylaromatic ester residues, such as 4-vinylphenyl. Methyl methacrylate, 2-ethylhexyl methacrylate and allyl methacrylate are preferred. Methyl methacrylate is particularly preferably used. Methacrylamides are also suitable. For example, N, N-dimethyl methacrylamide, N, N-diethyl methacrylamide, N, N-diisopropyl methacrylamide and N, N-di-n-butyl methacrylamide are suitable.

Suitable Acrylatmonomerbausteine are, for example, Cι ~ to C ₂ o ^_ alkyl acrylates. C 1 to C 1, in particular C 1 to C 3 alkyl acrylates are particularly preferred. The alkyl radicals can be linear, branched or form a ring. For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, i-pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, Octyl acrylate, n-decyl acrylate can be used. Also suitable are acrylates with an olefinically unsaturated ester unit, such as dihydrodicyclopentadienyl acrylate, allyl acrylate or those with aromatic groups, such as phenyl acrylate or 2-phenoxyethyl acrylate or vinyl aroma. table groups, such as 4-vinylphenyl. Acrylamides are also suitable. For example, N, N-dimethyl-acrylamide, N, N-diethylacrylamide, N, N-di-1-propylacrylamide and N, N-di-n-butylacrylamide are suitable.

In principle, all of the monomers mentioned can be used for the production of block copolymers. Preferred block copolymers are those which are composed of methyl methacrylate and n-butyl acrylate blocks, t-butyl acrylate blocks, t-butyl methacrylate or 2-ethylhexyl acrylate blocks, in particular of methyl methacrylate and t-butyl methacrylate.

The initiator composition can e.g. contain an alkali organic compound or a mixture of different such alkali organic compounds. Lithium, sodium or potassium are preferred as the alkali metal. The choice of the alkali metal influences, inter alia, the reaction rate of the polymerization reaction, so that the choice of the metal depends on the monomers to be reacted and the desired reaction rate. Organolithium compounds are generally preferred.

Alkyl or alkylarylalkali compounds are preferably used. Their alkyl radical generally has 1 to 10, preferably 1 to 6, carbon atoms and can be linear, branched or cyclic. The alkylaryl radical generally has 1 to 10, preferably 1 to 6, carbon atoms in the alkyl group. The alkyl group is also substituted by one or more aryl groups. Both monocyclic and polycyclic aryl radicals, which generally have 6 to 18 carbon atoms, are suitable as aryl radicals. The preferred aryl radical is optionally substituted phenyl. Alkylarylalkali compounds are accessible, for example, by reacting styrene or substituted styrenes such as α-methylstyrene or 1,1-diphenylethene or ring-alkylated styrenes with an alkylalkali compound, for example n-butyllithium, s-butyllithium or t-butyllithium. Instead of styrene or its derivatives, oligomers or polymers of these compounds can also be used. Representatives of the alkyl or alkylarylalkali compounds are, for example, n-butyllithium, s-butyllithium, t-butyllithium, diphenylmethyllithium, diphenylmethyl sodium, diphenylmethyl potassium, 1, 1, 4, 4-tetraphenylbutane-l, 4-dilithium, 1, 1, 4, 4-tetraphenylbutane-1, 4-disodium 1,1,4, 4-tetraphenylbutane-l, 4-dipotassium, 1-phenylhexyllithium, 1, 1-diphenylhexyllithium, 3-methyl-l-phenylpentyllithium, 1, 3-dimethyl -1-phenylpentyllithium or 3-methyl -1, 1 -diphenylpentyllithium. As a special organic alkali compound, the initiator composition can contain alkali ester enolate or a mixture of different such enolates.

The alkali metal isolates can be prepared separately and used as such.

The production of alkali enolates is known per se. They can be prepared, for example, by reacting an alkali salt, an alkylalkali compound or an alkali metal with an ester which has at least one acidic proton on the α-carbon atom. It goes without saying that diesters can also be converted into the alkali ester enolates contained according to the invention. The alkali metal isolates thus obtained can then be isolated and purified.

Esters of the general formulas II or III are preferred for the preparation of the alkali metal isolates:

H O

R ¹ CC OR ³ (II)

R ²

O H O

R ⁴ 0 CCC OR ^{6 (III)}

I.

R5 in which the radicals R ¹ to R ^{6 can be} identical or different from one another and independently of one another denote a C ₁ -C 10 -alkyl or C ₆ - C ₁ -C aryl radical. The radicals R ¹ , R ² and R ⁵ can also be hydrogen. The alkyl radicals can be either linear or branched. Preferred esters II or III contain as radicals R ³ , R ⁴ and R ⁶ Ci to C alkyl radicals such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl or t-butyl, including methyl or t-butyl are particularly preferred. The radicals R ¹ , R ² and R ⁵ are preferably Ci to Cs alkyl radicals, of which methyl, ethyl, i-butyl and 2, 2-dimethylpentyl are particularly preferred.

For example, lithium methyl isobutyrate, ethyl-α-lithio-isobutyrate or lithium t-butyl-isobutyrate can be obtained from esters of the general formula II. From the esters of the general formula II can also be prepared, for example, 2-lithium, 2, 4, 4-trimethylpentanoic acid methyl ester enolate. Lithium alkylmalonates such as 2 -Lithium- 2 - (Ci- to Cs-alkyl) -1, 3-propanedicarboxylic acid dialkyl ester enolates, in particular ^¬ 2 -Lithium-2-ethyl -1, 3-propanedicarboxylic acid dimethyl ester enolate, can be obtained from the ester of the general formula ( III) are produced.

Alkaline alcoholates are also preferred as component A). The underlying alcohols are those with a linear or branched aliphatic radical, such as methanol, ethanol, n-propanol, i-propanol, n-butanol, s-butanol or t-butanol. Cycloaliphatic alcohols such as cyclohexanol or 1-methylcyclohexanol are also possible. Sterically demanding alkoxide radicals such as tert are preferred. -Butoxide or i-propoxide. Lithium, sodium or potassium are preferred as alkali metal counterions. The choice of alkali metal can include the reaction rate of the polymerization reactions can be influenced. As a rule, lithium or potassium alkoxides are preferred. It is particularly preferred to use lithium or potassium tert. -Butoxide used. The production of these connections can be found e.g. in J. Organometal. Chem. 1973, 50, p. 9. For the production of potassium tert. -Butoxide can also be prepared according to a specification by Johnson and Schneider, Org. Synth., 1963, Coll. Vol. 4, p. 132. Alkaline alcoholates A) also include compounds which are derived from diols, in particular vicinal diols, and also from polyols. Glycol, glycerol, 2,3-dimethylbutane-2,3-diol or 3,4-diethyl-hexane-3,4-diol may be mentioned as examples. Vicinal diols are, for example, by reductive coupling of ketones (see also Vogel's Textbook of Practical Organic Chemistry, 5th ed., 1989, Longman Scientific & Technical) or by

Dihydroxylation of alkenes obtained (see also Chem. Rev. 1980, 80, p. 187). The preparation of monoalcoholates described above can be used to produce corresponding bisalkali alcoholates.

Also preferred as component A) are alkali amides. Suitable alkali amides can be derived from aliphatic or aromatic amines or from those with an aliphatic and aromatic radical. Aliphatic as well as aromatic amines can have both identical and different substituents. Dimethylamine, diethylamine, di-i-propylamine, di-n-butylamine and di-t-butylamine are suitable as aliphatic amines. Amines with bulky groups such as di-i-propylamine are preferably used. Lithium, sodium or potassium are preferred as alkali metal counterions. Lithium amides such as lithium di-i-propylamide are particularly suitable. Some alkali amides, for example lithium di-i-propylamide, can be purchased commercially or in accordance with the regulations of, for example, House et al. (J. Org. Chem., 1978, 43, p. 700) or Reetz et al. (Liebigs Ann. Chem., 1980, p. 1471).

Different alkali ester enates, alkali alcoholates or alkali amides can also be used, so that different starter enolates, alkali alcoholates or alkali amides are contained in the starter composition.

In addition to an alkali ester enolate, an alkali alcoholate or alkali amide, the starter ^composition according to the invention contains an organic aluminum compound (component B)). Besides, it is also possible according to the invention different aluminum compounds ^¬ use. Aluminum alkyl compounds are preferred. The alkyl radicals on the aluminum can be the same or different and generally contain from 1 to 10, preferably 1 to 6, carbon atoms. They can be linear or branched, but can also be cyclic. As aluminum compounds, trimethyl aluminum, triethyl aluminum, tri-i-propyl aluminum, triisobutyl aluminum, tri (neopentyl) aluminum or tri (norbornyl) aluminum can be mentioned as examples. Aluminum alkyl alcoholates and optionally alkyl- or alkoxy-substituted aluminum alkylphenolates on the phenyl ring, such as, for example, diisobutylaluminum-2, 6 -ditert, are also suitable. -butyl-4-methylphenolate.

According to the invention, the starter composition contains an additive C) complexing alkali cations. This includes at ^¬ play, salts of alkali and alkaline earth metals. Among the cations of the alkali metals, the cesium cation, the potassium and the sodium cation are preferably used, with the cesium cation being particularly preferred. Suitable alkaline earth metal cations are based on magnesium, calcium, strontium and barium. Calcium or magnesium are preferred among the alkaline earth metal cations.

The cations mentioned are usually in the form of their salts of inorganic acids, for example as halides, pseudohalides, chlorates, perchlorates, nitrates, sulfonates, trifluoromethanesulfonates, tetrafluoroborates, tetraphenylborates, hexafluorophosphates, hexafluoroantimonates, hexafluorostilates or organic acids with a smaller _p or organic acid 20, for example used as alcoholates, acetates or benzoates. They are particularly preferably used as halides, in particular fluorides, chlorides, bromides or iodides or in the form of the cyanides or rhodanides. The fluorides, chlorides or bromides of potassium or cesium are preferably used. Cesium fluoride is particularly preferred and cesium chloride. Any mixtures of the alkali metal and alkaline earth metal salts listed can also be used as component C). In general, the salts of cesium are particularly preferred.

Depending on the desired polymerization result or desired polymerization parameters such as the speed of the reaction, the composition of the starter can vary within wide limits. In general, the starter composition contains the aluminum alkyl compound to compound A) in a molar ratio of 0.5: 1 to 50: 1, preferably from 1: 1 to 30: 1, the additive C) to compound A) in a molar ratio of 0.5: 1 to 1000: 1, preferably from 1: 1 to 200: 1, particularly preferably from 1: 1 to 20: 1.

As a rule, the molar ratio of monomer to compound A) is selected in the range from 5: 1 to 10000: 1. Preferred molar ratios of monomer to compound A) are in the range from 10: 1 to 5000: 1, in particular from 50: 1 to 3000: 1.

The polymerization can be carried out either in the absence or in the presence of a solvent. In general, the polymerization is carried out in a solvent. Non-polar solvents are preferably used. These include aromatic hydrocarbons such as toluene, benzene, xylene or ethylbenzene. However, substances, mixtures of different non-polar solvents such as mixtures of toluene with ethylbenzene, or mixtures of aromatic and aliphatic hydrocarbon ^¬ such as cyclohexane, hexane or pentane may be used. The preferred solvent is toluene or ethylbenzene. Solvents are preferably used which have the high purity required for the process.

If polymerization is carried out in the presence of a solvent, the reaction of the monomers can be carried out at different degrees of dilution. For example, the proportion by weight of the monomers in the total batch can be in the range from 0.5 to 80%, preferably from 1 to 50%.

In principle, the components of the starter composition, the solvent and the monomers can be mixed with one another in the most varied of orders. For example, all of the starter components can be introduced and the solvent and monomer can then be added. However, some of the starter components can also be used initially and some other starter components can be added later. It is also possible to add further amounts during the polymerization reaction Add starter composition. For example, a suitable embodiment is presented according to the solvent and next to ^¬ with the aluminum compound is added. The mixture, for example the alkali metal isolate or the alkali metal alcoholate, which was prepared separately, can then be added to this mixture. Alternatively, as already described above, an alkyl or alkylarylalkali compound can be added to the alkali enolate and then converted into the alkali enolate in situ by reaction with a stoichiometric amount of an alkyl methacrylate, preferably the monomer used in the polymerization. Generally, the alkali ion complexing additive and then the monomer are added. In a preferred embodiment, the alkali or alkaline earth metal salt, for example a cesium halide, is introduced and the solvent and the aluminum compound are added, the order in which the latter two components are added is not critical. The separately prepared component A) can then be added to this mixture before the monomer is added. In a further embodiment, be ^¬ vorzugten aluminum compound and solvent are initially introduced medium and then an alkali metal or alkaline earth metal salt added. Subsequently, component A), prepared separately, for example an alkali metal alkoxide, alcoholate or amide, is added to the initiator composition and, in the last step, the monomers to be used in the polymerization are added. The individual components of the starter composition can be used as such. It is also possible to use the components of the starter composition dissolved or dispersed in one of the solvents or solvent mixtures mentioned. The components are preferably used dissolved in pentane, hexane, toluene, ethylbenzene or cyclohexane. It is possible to add the total amount of monomers at once, in stages or continuously.

For methacrylates as monomers, the reaction can be carried out, for example, at a temperature in the range from -78 to + 50.degree. A temperature range from -30 to + 30 ° C., in particular from -20 to 0 ° C., is preferred. If acrylates are used as monomers, a reaction temperature of -78 to -20 ° C has proven to be advantageous. During the reaction, the temperature can either be kept almost constant or the reaction can be subjected to a temperature program.

After the molecular weight has been built up, the polymerization reaction is generally terminated by adding a protic substance, such as, for example, an alcohol such as methanol or ethanol or acetic acid, formic acid, hydrochloric acid or water or a mixture of these compounds. The reaction mixture can then be worked up, for example, by methods known per se. For example, the poly (meth) acrylate obtained can be precipitated using a lower alcohol or water or the solvent can be removed from the reaction mixture.

Polymethacrylates and in particular also acrylates can be easily produced by the process according to the invention. The poly (meth) acrylates obtainable by the process according to the invention generally have molecular weights (number average values M _n ) in the range from 500 to 1,000,000, preferably in the range from 5,000 to 300,000 g / mol. Since gel formation does not occur or only occurs to a minor extent in the process according to the invention, they have a narrow molecular weight distribution, given as the ratio of weight average to number average M _w / M _n . M _w / M _n is generally in the range from 1.05 to 1.6, preferably in the range from 1.05 to 1.4. In addition, poly (meth) acrylates of high syndiotacticity are obtained by the process according to the invention. The proportion of the syndiotactic triads rr is generally from 50 to 85%, preferably from 60 to 80%.

The process according to the invention is distinguished on the one hand by the fact that the process parameters such as reaction rate and temperature can be controlled well. On the other hand, complete or almost complete sales can be achieved. In addition, the "living" polymer chain ends are characterized by increased stability. In addition, the process is much less sensitive to contaminants present in the technical grade solvents and monomers than known processes.

In addition, block copolymers can be produced using the process according to the invention. For this purpose, the polymerization reaction is not terminated with protic substances after the molecular weight has been reduced, but rather other monomers or monomer mixtures different from the first addition are added. In this way, several blocks can be attached.

Examples

The examples were carried out with the exclusion of oxygen and moisture in the customary protective gas technology.

The number and weight average molecular weights Mn and Mw were determined by gel permeation chromatography, unless stated otherwise, using poly-n-butyl acrylate and polymethyl methacrylate standards. The tacticity of the The poly (meth) acrylates obtained were determined by means of ⁱ H-MR spectroscopy.

Preparation and purification of the starting compounds:

Ethyl-α-lithioisobutyrate (EiBLi) was prepared from ethyl isobutyrate and lithium isopropylamide in hexane and recrystallized from diethyl ether.

Potassium tert. -Butoxide was prepared by stirring potassium in t-butanol under a protective gas and was isolated in the form of a powder by filtration and removal of excess alcohol in vacuo.

Triisobutylaluminum (AÜBU ₃ ) was as 25 wt. % solution in toluene obtained from Aldrich.

Cesium fluoride (99.9%) was obtained from Aldrich and used without further purification.

Cesium chloride (99.9%) of the Fa. Aldrich was at 200 ° C in the high ^¬ vacuum dried.

Triethylaluminum (AlEt ₃ ) was obtained from Aldrich as a 1.9 M solution in toluene.

The toluene used was stirred over Na / K alloy and distilled.

The monomeric (meth) acrylates were cleaned using a nitrogen purge, aluminum oxide and calcium hydride and then distilled in vacuo.

General procedural conditions:

Examples 1 and 2

Cesium fluoride was taken up in toluene, triisobutylaluminum was added and the mixture was transferred to the reactor vessel cooled to -78 ° C. Ethyl α-lithioisobutyrate (EiBLi) in toluene and n-butyl acrylate in toluene were added with stirring. The amount of toluene was calculated so that the total volume of the reaction solution was 100 ml. The reaction was stopped by adding 5 ml and a methanol / glacial acetic acid mixture (9: 1) and the solvents were removed in vacuo. The resulting polymer was taken up in benzene, filtered and freeze-dried. Properties of the polymers obtained and reaction parameters are summarized in Table 1. Example 3

Instead of ethyl α-lithioisobutyrate (EiBLi), potassium tert was used as component A). -butoxide used.

Comparative Example VI

In deviation from the instructions in Examples 1 and 2, no cesium fluoride and no triisobutyl aluminum were used. Otherwise, the procedure was analogous to that of Examples 1 and 2 (see also Table 1).

Comparative example V2

In deviation from the instructions in Examples 1 and 2, the addition of cesium fluoride to the reaction mixture was dispensed with.

Table 1

^a) determined by means of gel permeation chromatography using a poly-n-butyl acrylate standard ^b) as initiator component A), potassium tert-butoxide was used instead of ethyl α-lithioisobutyrate

Example 4

Cesium chloride (0.69 mmol) was dissolved with triethyl aluminum (1.5 mmol) in 10 ml of toluene at room temperature while stirring and 65 ml of toluene were added.

With stirring, ethyl α-lithioisobutyrate (EiBLi) (0.344 mmol) was dissolved in 10 ml of toluene at room temperature and added to the cesium chloride / triethyl aluminum mixture. This mixture was heated to -20 ° C. and methyl methacrylate (69 mmol) in 10 ml of toluene was added with stirring. After 2 hours, the reaction was stopped and worked up analogously to Examples 1 and 2.

Table 2

^a > determined by gel permeation chromatography using a polymethyl methacrylate standard

Claims

claims

1. A process for the preparation of homo-, co- or block copolymers by anionic polymerization of acrylates and / or methacrylates in the presence of an initiator composition, characterized in that the initiator composition contains ^¬ composition

A) an alkali organic compound, an alkali alkoxide or an alkali amide,

B) an organic aluminum compound and

2. The method according to claim 1, characterized in that an alkali metal enolate is used as the alkali organic compound A).

3. The method according to claim 1, characterized in that an organic lithium compound is used as the alkali organic compound A).

4. Process according to claims 1 to 3, characterized in that the alkali metal alkoxide A) is lithium or potassium tert. -

Butoxide or used as alkali amide A) lithium diisopropylamide.

5. Process according to claims 1 to 4, characterized in that one as an organic aluminum compound B)

Alkyl aluminum compound used.

6. Process according to claims 1 to 5, characterized in that salts of cesium are used as additive C).

7. Process according to claims 1 to 6, characterized in that one carries out the polymerization reaction in a non-polar solvent.

8. initiator composition containing components A), B) and C) according to claims 1 to 6.

9. A process for the preparation of an initiator composition according to claim 8, characterized in that in a first step an alkyl or alkylarylalkali compound is mixed with an aluminum alkyl compound, in a second step a stoichiometric amount for the alkali compound of an alkyl (meth) acrylate and in a third step adds the complexing additive C) according to claim 1.

10. Use of the initiator composition according to claim 8 for homo-, co- or block copolymerization of acrylates and / or methacrylates.