EP2658880A2

EP2658880A2 - Polymers comprising hydroxyl groups and ester groups and method for the production thereof

Info

Publication number: EP2658880A2
Application number: EP11794410.8A
Authority: EP
Inventors: Matthias Krull; Roman MORSCHHÄUSER; Hans Jürgen SCHOLZ; Jochen Stock
Original assignee: Clariant Finance BVI Ltd
Current assignee: Clariant International Ltd
Priority date: 2010-12-30
Filing date: 2011-12-08
Publication date: 2013-11-06
Also published as: WO2012089300A3; JP2014504656A; KR20140009272A; US20130289206A1; DE102010056578A1; CN103492427A; WO2012089300A2; BR112013016864A2

Abstract

The invention relates to polymers comprising ester/hydroxyl groups, containing repetitive structural units of formulae (I) and (II) in blocks, alternatively or statistically in her Abfolge (I), (II) wherein D represents a direct bond between the polymer backbone and the hydroxyl group, a C-₁-to C₆-alkylene group, a C₅- to C₁₂-arylene group, a oxyalkylene group of formula -O-R²-, an ester group of formula -C(O)-O-R²- or an amide group of formula -C(O)-N(R³)R²-, E represents a hydrocarbon group having 1 to 10 C-atoms, R¹ represents hydrogen, a hydrocarbon group having 1 to 50 C-atoms or an acyl group of formula -C(O)-R⁴, R² represents a C₂- to C₁₀-alkylene group, R³ represents hydrogen or a C₁- to C₁₀-alkyl group, which can have substituents, R4 represents a hydrocarbon group having 1 to 50 C-atoms, A represents a C₂- to C₁₀-alkylene group, k represents a number between 1 and 100, n represents a number from 0 to 4999, m represents a number from 1 to 5000, n+m for a number from 10 to 5000, under the proviso that a) the molar fraction of the structural units (I) on the polymer is between 0 and 99,9 mol-%, and b) the molar fraction of the structural units (II) on the polymers between 0.1 and 100 mol-% of repetitive units. The invention also relates to a method for the production of said polymers by exposing a polymer reaction mixture containing hydroxyl groups and ether carbon esters to microwaves.

Description

description

Hydroxyl groups and ester-bearing polymers and processes for their preparation

The present invention relates to hydroxyl groups and ester group-bearing polymers and to a process for their preparation by polymer analogues

Esterification of aqueous solutions of the polymers in the microwave field. Higher molecular weight synthetic polymers bearing a variety of hydroxyl groups, such as poly (vinyl alcohol), are nonionic, water-soluble, thermoplastics that transition to highly viscous masses above their melting point. The water solubility of the polymers is dependent inter alia on the concentration of hydroxyl groups in the polymer and in the specific case of poly (vinyl alcohol) also a function of the degree of hydrolysis of the poly (vinyl acetate) used for its preparation. For example, poly (vinyl alcohol) of high degree of hydrolysis is highly crystalline and soluble only in hot water. Poly (vinyl alcohol) has interesting physicochemical

Properties such as film and film formation, emulsifying behavior and adhesion make it interesting for a large number of technical applications. Furthermore, it has a high tensile strength, which, however, gives way to increasing elasticity with increasing moisture content, for example with increasing humidity, which is manifested, for example, in a greater extensibility of films. By chemical modification, the properties of hydroxyl-bearing polymers can be influenced within wide limits. So can

For example, by hydrophobic modification their resistance to chemicals and solvents as well as their temperature stability can be improved. On the other hand, in the case of poly (vinyl alcohol), for example, after hydrophobic modification, the tensile strength is maintained even at high atmospheric humidity without losing water solubility. For various applications, for example in the textile industry, especially in cold water more soluble polyvinyl alcohols with increased elasticity and increased Stretching is beneficial as it is less brittle on the fiber and after the

Processing of the fiber would be easier to remove. The should

Solution viscosity of the polymers but not appreciably increase to the

Use with existing techniques to make. About the usual methods for the derivatization of polyvinyl alcohol such as

for example, acetalization with aldehydes is the desired one

Property profile not adjustable.

It would be desirable to modify water-soluble, hydroxyl-bearing and thus nonionic polymers containing side chain polyether groups. A suitable method would be, for example, the alkoxylation of with alkylene oxides. In the case of direct alkoxylation, the low solubility of polymers bearing hydroxyl groups in organic solvents causes considerable preparative difficulties in the reaction and in particular in the preparation of homogeneous products. For polymer-analogous reactions, the polymer to be reacted must be brought into a soluble or at least swollen form to ensure a homogeneous reaction. If the polymer is insoluble in the reaction medium, only

Surface reactions possible; if the polymer is swollen in the reaction medium, the reaction rate depends on the accessibility of the functional groups in the pores of the polymer matrix. Moreover, in partially crystalline polymers, reactions take place practically only in the amorphous regions, since diffusion processes in the crystalline region are very slow. Hydroxyl-bearing polymers such as, for example, polyvinyl alcohol are in solvent-free form solids or highly viscous masses, which must be fluidized for homogeneous chemical reactions either thermally or by means of solvents. Preferred solvent for most hydroxyl-bearing polymers is water. For alkoxylations, however, water is usually less suitable as a solvent because it leads primarily to the formation of glycol and polyglycols and not to the etherification of the alcoholic hydroxyl groups. Although such polymers such as poly (vinyl alcohol) usually in polar aprotic solvents such as Dimethyl sulfoxide, formamide, dimethylformamide and

Dissolve phosphoric acid trisdimethylamide. Upon removal of these high boiling solvents after reaction, the polymer usually suffers

thermal damage, which makes them often unusable for further use.

A polymer-analogous esterification of hydroxyl-bearing polymers with ether carboxylic acids would lead to comparable structures. For

Condensation reactions, however, water is usually less suitable as a solvent because it shifts the reaction equilibrium in favor of the educts.

The preparation of corresponding (co) polymers by (co) polymerization of, for example, vinyl acetate with poly (oxyalkylene) units bearing monomers are also limited, since suitable monomers such as polyoxyalkylene esters of ethylenically unsaturated carboxylic acids technically limited access and very expensive in most cases , In addition, in the subsequent required hydrolysis of the acyl groups to hydroxyl groups and the ester groups of the comonomers are at least partially hydrolyzed. According to the prior art, a polymer-analogous esterification of hydroxyl-bearing polymers with hydrophobic, long-chain carboxylic acids with reactive acid derivatives such as acid anhydrides or acid chlorides is possible. However, at least equimolar amounts of carboxylic acids or salts which are to be separated off and disposed of or worked up and which cause high costs arise. Since hydroxyl-carrying polymers such as poly (vinyl alcohol) are essentially only soluble in water, further undesirable by-products are formed by reaction of the reactive acid derivative with water. Corresponding reactive acid anhydrides or acid chlorides of polyoxyalkylene-bearing carboxylic acids such as

Ethercarboxylic acids are at least technically not available, so that such polymer-analogous modifications are not accessible.

Esterification of hydroxyl-bearing polymers with ether carboxylic acids On the other hand, because of the different viscosities of polymers and acids and the insolubility of the polymers in organic solvents, it is also problematic in a direct way. According to US-2601561 succeeds

Esterification of poly (vinyl alcohol) with, based on the hydroxyl groups, at least equimolar amounts of ethylenically unsaturated carboxylic acids having at least 14 carbon atoms in solvents such as phenol, cresol or xylenol. The esterification requires temperatures between 150 and 250 ° C and takes 2 to 5 hours. The products obtained are intensely tanned in color and on the one hand contain high molecular weight crosslinked components and on the other hand

low molecular weight degradation products. Even after workup, they still contain residual amounts of the low-volatile, toxicologically questionable solvents.

A recent approach to chemical synthesis are reactions in the microwave field. In this case, a significant acceleration of the reactions is often observed, which makes these methods both economically and ecologically very interesting. Thus, various esterifications of carbohydrates are disclosed in the prior art, which were almost without exception with fatty acid esters, which have a higher reactivity than the free fatty acids, and still lead only to very low degrees of acylation. CN-1749279 teaches that when carbohydrates are reacted with acids at elevated temperature, degradation of the polymer occurs at the same time, which, depending on the raw material used and the reaction conditions chosen, leads to highly volatile products

Properties leads. It was therefore an object to provide a method for polymer-analogous modification of hydroxyl-bearing main chain polymers containing polyoxyalkylene groups side chains, with the properties of such nonionic, water-soluble polymers can be modified in a simple and inexpensive manner in industrially interesting amounts. Of particular interest is the esterification of secondary hydroxyl-bearing linear addition polymers and in particular of secondary hydroxyl-bearing linear addition polymers with backbone composed only of C-C bonds. In particular, the elasticity and thus the elongation of the polymers be increased while improving their solubility, especially in cold water. In addition, the solution viscosity of the polymers should not differ significantly from the viscosity of the underlying polymers in order to apply them to existing machines of known technology. To achieve constant product properties both within one

Reaction approach as well as between different reaction mixtures, the modification should be as homogeneous as possible, that is done in statistical distribution over the entire polymer. Furthermore, there should be no reactions on the polymer backbone, in particular polymer degradation, and no appreciable amounts of toxicologically and / or ecologically harmful by-products should arise.

Surprisingly, it has been found that higher molecular weight,

Hydroxyl-carrying polymers in aqueous solution and / or in solutions of water and water-miscible organic solvents with

Ethercarboxylic acids under the influence of microwaves at temperatures above 100 ° C esterify. In this way, the elasticity of hydroxyl-bearing polymers can be significantly increased with comparable tensile strength. At the same time the solubility in cold water is significantly improved. The dissolution behavior of such modified polymers gives no indication of the presence of larger hydrophilic or hydrophobic polymer blocks. Since a large number of different ether carboxylic acids can be obtained inexpensively and in technical quantities, the properties of said polymers can be modified within wide limits in this way. It does not come to the degradation of

Polymer chains.

Accordingly, the invention relates to esters of hydroxyl-bearing polymers containing repeating structural units of the formulas (I) and (II) in blockwise, alternating or random sequence

for a direct bond between polymer backbone and hydroxyl group, a cis-C ₆ alkylene group, a C 5 to C 12 arylene group, a

Oxyalkylene group of the formula -OR ² -, an ester group of the formula -C (O> -O-R ² - or an amide group of the formula -C (O) -N (R ³ ) R ² -,

E for a hydrocarbon radical having 1 to 10 carbon atoms

R ^{1 is} hydrogen, a hydrocarbon radical having 1 to 50 carbon atoms or an acyl radical of the formula -C (0) -R ⁴

R ^{2 is} a C ₂ - to C 10 -alkylene radical,

R ^{3 is} hydrogen or a C ¹ -C 10 -alkyl radical which may carry substituents,

R ^{4 is} a hydrocarbon radical having 1 to 50 C atoms,

A is a C 2 -C 10 -alkylene radical,

k for a number between 1 and 100,

n for a number from 0 to 4999,

m for a number from 1 to 5000,

n + m is a number from 10 to 5,000, with the proviso that a) the molar fraction of the structural units (I) on the polymer is between 0 and 99.9 mol%, and

b) the molar fraction of the structural units (II) on the polymer is between 0.1 and 100 mol% of the repetitive units.

Another object of the invention is a process for the preparation of esters of hydroxyl-bearing polymers containing repetitive

Structural units of the formulas (I) and (II) in blockwise, alternating or statistical sequence

wherein

D for a direct bond between the polymer backbone and the hydroxyl group, a C ₁ - to C ₆ -alkylene group, a C ₅ - to C ₂ -arylene group, a

Oxyalkylene group of the formula -OR ² -, an ester group of the formula -C (O) -O-R ² - or an amide group of the formula -C (O) -N (R ³ ) R ² -,

E for a hydrocarbon radical having 1 to 10 carbon atoms

R ^{2 is} a C ₂ - to Cio-alkylene radical,

R ^{3 is} hydrogen or a C ₁ -C 10 -alkyl radical which may carry substituents,

R ⁴ for a hydrocarbon radical having 1 to 50 carbon atoms

A is a C ₂ - to C 10 -alkylene radical,

k for a number between 1 and 100,

n for a number from 0 to 4999,

m for a number from 1 to 5000,

n + m is a number from 10 to 5,000, with the proviso that a) the molar fraction of the structural units (I) on the polymer is between 0 and

99.9 mol%, and

b) the molar fraction of the structural units (II) on the polymer is between 0.1 and 100 mol% of the repetitive units,

in the hydroxyl group-carrying polymer A), which is the repetitive

Structural unit of the formula (I), with ether carboxylic acids B1) of the formula (III) or ether carboxylic acid esters B2) of the formula (IV)

R ¹ -O [-A-O] _k -E-COOH (III) R - O [-A-O] _k -E -COOR ⁵ (IV) where R ¹ , A, E and k have the meanings given above and R ^{5 is} a Ci-C4-alkyl radical, are irradiated in the presence of water with microwaves, wherein the reaction mixture is heated by the microwave irradiation to temperatures above 100 ° C. Another object of the invention are esters of hydroxyl-bearing polymers containing repetitive structural units of the formulas (I) and (II) in blockwise, alternating or random sequence, prepared by

Reaction of hydroxyl-carrying polymers A), the repetitive

Structural units of the formula (I), in the presence of ether carboxylic acids of the formula (III) or Ethercarbonsäureestern of formula (IV) and in the presence of water under irradiation with microwaves, wherein the reaction mixture is heated by the microwave irradiation to temperatures above 100 ° C.

Preferred hydroxyl-carrying polymers A) are main chain polymers, the polymer backbone is composed only of C-C bonds and the

accordingly contains no heteroatoms. However, preferred hydroxyl-bearing polymers A) may have groups at the chain end

Contain heteroatoms, for example, enter the polymer during the polymerization by the initiator and / or the moderator. Preferably, the polymer A) contains a total of at least 5, more preferably at least 10, especially at least 15 and in particular at least 20 hydroxyl-bearing monomer units, d. H. n is at least 5, 10, 15 or 20. These monomer units may also be combined with or interspersed with structural units derived from other monomers in copolymers.

D is preferably a direct bond between the polymer backbone and the hydroxyl group. The structural unit of the formula (I) is in this case from

Derived from vinyl alcohol. In a further preferred embodiment, D stands for a linear or branched alkylene radical. This preferably has one, two, three or four carbon atoms. These are, for example, structural units derived from allyl alcohol or from 3-buten-1-ol 3-buten-1-ol, 1-penten-3-ol or 4-penten-1-ol. In a further preferred embodiment, D is an oxyalkylene group in which R ^{2 is} preferably an alkylene group having two, three or four C atoms. Such structural units (I) are preferably derived from hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether or

Hydroxybutylvinylether from. In another preferred embodiment, D is an ester group. R ² here preferably stands for an alkylene group having 2 or 3 C atoms. Such structural units (I) are derived, for example, from

Hydroxyalkyl esters of acrylic acid and methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and

Hydroxypropyl methacrylate from. In a further preferred embodiment, D is an amide group which is connected via a group R ² to the hydroxyl group. R ² here preferably stands for an alkyl group having 2 or 3 C atoms. R ³ may, if it is an alkyl radical, carry substituents such as, for example, a hydroxyl group. Preferably, R ^{3 is} hydrogen, methyl, ethyl or hydroxyethyl. Such structural units (I) are derived, for example, from

Hydroxyalkylamiden of acrylic acid and methacrylic acid such as hydroxyethylacrylamide, hydroxyethylmethacrylamide, hydroxypropylacrylamide,

Hydroxypropylmethacrylamid from. Also, several, for example, two, three, four or more different structural units of the formula (I) containing polymers are suitable according to the invention. The inventive method is

particularly suitable for the esterification secondary OH-bearing polymers.

Particularly preferred structural units of the formula (I) are derived from

From ethanol. The inventive method is also suitable for the modification of

Copolymers of hydroxyl-carrying monomers, in addition to the

Hydroxyl-containing units of the formula (I) have structural elements which are derived from one or more further monomers which are not Wear hydroxyl groups. Preferred further monomers are olefins, esters and amides of acrylic acid and methacrylic acid, vinyl esters, vinyl ethers, vinylamines, allylamines, and derivatives thereof. Examples of preferred comonomers are ethene, propene, styrene, methyl acrylate, methyl methacrylate and esters of acrylic acid and methacrylic acid with alcohols having 2 to 24 carbon atoms. Preferably included

Copolymers more than 10 mol%, particularly preferably 15-99.5 mol%,

in particular 20 to 98 mol%, especially 50 to 95 mol%, for example

70-90 mol% of structural units (I) derived from a hydroxyl group-carrying monomer.

Examples of suitable copolymers A) are copolymers of vinyl alcohol with vinyl esters, in particular copolymers of vinyl alcohol with vinyl acetate, as are obtainable, for example, by partial saponification of polyvinyl acetate. Preferred are copolymers which in addition to vinyl alcohol 0.5 to 60 mol% and particularly preferably 1 to 50 mol% such as 1, 5 to 10 mol%

Contain vinyl acetate. Starting from partially hydrolyzed poly (vinyl acetate), terpolymers of vinyl acetate, vinyl alcohol and vinyl alcohol esterified according to the invention with a carboxylic acid of the formula (II) and / or a carboxylic acid ester of the formula (III) can thus also be prepared by the process according to the invention. Furthermore, ester groups present in the copolymer A) can be completely or partially transesterified in the process according to the invention.

Examples of other suitable copolymers A) are copolymers of vinyl alcohol and ethylene, vinyl alcohol and styrene and copolymers

Hydroxyethyl methacrylate and methyl methacrylate.

Preferred copolymers A) are homogeneously soluble or at least swellable in water or solvent mixtures of water and water-miscible organic solvent at temperatures above 40 ° C., for example at 50 ° C., 60 ° C., 70 ° C., 80 ° C. or 90 ° C. , Furthermore, they are preferred with a

Concentration of at least 1 wt .-% and in particular 5 to 90 wt .-% such as 20 to 80 wt .-% at temperatures above 40 ° C as

for example, at 50 ° C, 60 ° C, 70 ° C, 80 ° C or 90 ° C homogeneous in water or Solvent mixtures of water and water-miscible organic solvent soluble or swellable.

Particularly preferred hydroxyl-bearing main chain polymers A) are poly (vinyl alcohols). Under poly (vinyl alcohols) are understood according to the invention both homopolymers of vinyl alcohol and copolymers of vinyl alcohol with other monomers. Particularly preferred copolymers are those which contain 0.5 to 20 mol%, preferably 1 to 15 mol% vinyl ester. These are usually prepared by polymerization or copolymerization of esters of vinyl alcohol with lower carboxylic acids and subsequent hydrolysis of the ester. Preferred ester of the vinyl alcohol is vinyl acetate. The

Hydrolysis of the polymers can be complete or partial.

Further particularly preferred copolymers are copolymers of ethylene and vinyl alcohol. Especially preferred are those which are 15-70 mol% and especially 20-60 mol%, such as 25-50 mol% of ethylene derived

Contain structural units.

The weight-average molecular weight M _{w of} preferred polymers A), determined on acetylated samples by gel permeation chromatography and static light scattering, is preferably between 10,000 and 500,000, especially between 12,000 and 300,000 and in particular between 15,000 and 250,000 g / mol. The molecular weight of the modified polymers is according to their

Increased degree of esterification and the molecular weight of the acyl radical.

Suitable ether carboxylic acids B1 are generally compounds which have at least one carboxyl group and at least one ether group in the acid radical. Thus, the inventive method is also for the implementation of

Ethercarbonsäuren with, for example, two, three, four or more carboxyl groups suitable. Preferred ether carboxylic acids have a carboxyl group.

The preparation according to the invention suitable ether carboxylic acids B1) is known in principle. It succeeds, for example, by reacting polyglycols of Formula (V)

R ¹ -O [-A-0] _k -H (V) wherein R ¹ , A and k have the abovementioned meaning, with

Halocarboxylic acids or their alkali metal salts such as with

Sodium chloroacetate or by direct oxidation of polyglycols. Preferably, E is an alkylene group having one, two, three or four C atoms and in particular a methylene group. Preferred ether carboxylic acids contain polyoxyalkylene groups having 2 to 70, more preferably 5 to 50 and

in particular with 10 to 30 units derived from at least one alkylene oxide - [AO] -, that is k preferably stands for a number from 2 to 70, particularly prefers a number from 5 to 50 and in particular for a number from 0 to 30. Preferred Alkylene oxides for the preparation of the ether carboxylic acids B1) are ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. A is therefore preferably an alkylene radical having two, three or four C atoms.

For the preparation of the ether carboxylic acids B1) suitable polyglycols of

Formula (V) are accessible, for example, by reacting alkylene oxides with water, alcohols or carboxylic acids. In the reaction with water, R ^{1 is} hydrogen. In this embodiment, it may also come in the implementation of the ether carboxylic acid to the formation of double-sided carboxyl-bearing ether carboxylic acids. These ether carboxylic acids correspond to the formulas HOOC-E-O [-A-O] _k -E-COOH (IIIa) R ⁵ OOC-E-O [-A-O] _k -E-COOR ⁵ (IVa)

These are suitable according to the invention as ether carboxylic acid B1), wherein it in the reaction with the hydroxyl-carrying polymers A) to

Crosslinking reactions and an associated strong increase in molecular weight can come. The resulting crosslinked polymers comprise a structure in which two polymer chains through their D-O structural unit of formula I by means of the group derived from the ether carboxylic acid

-OOC-EO [-AO] _k -E-COO- are connected. In the reaction with alcohols arise polyglycols (V) in which R ^{1 is} a hydrocarbon radical having preferably 2 to 36, more preferably 4 to 24 and in particular 6 to 20 carbon atoms. The hydrocarbon radical may be aliphatic, cycloaliphatic, aromatic or araliphatic. It is preferably aliphatic. Particularly preferred alcohols are lower alcohols having 1 to 6 carbon atoms such as methanol and ethanol, fatty alcohols of natural or synthetic origin having 7 to 20 carbon atoms such as oleyl, Cocosfett-, tallow fat and

Behenyl alcohol and phenol and alkylphenols with C 1 -C ₃₆ -alkyl radicals and in particular with C ₄ -C ₁₂ -alkyl radicals. In the reaction with carboxylic acids arise Poylglykole (V) in which R ^{1 is} an acyl radical of the formula -C (0) -R ⁴ , in which R ^{4 is} a hydrocarbon radical having preferably 2 to 36, particularly preferably 4 to 24 and especially with 6 to 20 carbon atoms. The hydrocarbon radical R ⁴ may be aliphatic, cycloaliphatic, aromatic or araliphatic. It is preferably aliphatic. The hydrocarbon radical R ⁴ as well as the acyl radical R ¹ may independently of one another contain one or more, for example two, three, four or more further substituents, for example hydroxyalkyl, alkoxy, for example methoxy, poly (alkoxy) -,

Poly (alkoxy) alkyl, amide, cyano, nitrile, nitro and / or C ₅ -C ₂ o aryl groups, such as phenyl groups, are provided with the proviso that the substituents are stable under the reaction conditions and no side reactions such as elimination reactions received. The hydrocarbon radical R ¹ may also contain heteroatoms such as, for example, oxygen, nitrogen, phosphorus and / or sulfur, but preferably not more than one heteroatom per

2 C atoms.

Mixtures of various ether carboxylic acids are also suitable for use in the process according to the invention.

The ethercarboxylic esters B2) which are suitable according to the invention are esters of the abovementioned ethercarboxylic acids B) with alcohols of the general formula R ⁵ -OH. R ⁵ is preferably an alkyl radical with 1, 2 or

3 C atoms. Particularly preferred alcohols are methanol and ethanol. Hydroxyl-carrying polymers A) and ether carboxylic acids B1) or

Ethercarbonsäureester B2) are preferably used in a ratio of 100: 1 to 1: 1, more preferably in a ratio of 10: 1 to 1, 1: and especially in the ratio 8: 1 to 1, 2: used, in each case based on the molar equivalents of hydroxyl-bearing structures of the formula (I) and the carboxyl groups of the formula (III) or the ester groups of the formula (IV). By the ratio of ether carboxylic acids B1) or Ethercarbonsäureestern B2) to hydroxyl groups of the polymer, the degree of modification and thus the properties of the product can be adjusted. If ether carboxylic acid B1) or Ethercarbonsäureester B2) im

Excess used or are not completely reacted, portions thereof remain unreacted in the polymer, which can remain depending on the purpose in the product or can be separated. The esterification of the free hydroxyl groups of the polymer A) can therefore take place completely or only partially. In the case of partial esterification, preferably 1 to 99%, particularly preferably 2 to 90, in particular 5 to 70% and especially 10 to 50%, for example 20 to 40% of the hydroxyl groups, are esterified.

Particularly preferred is the inventive method for the partial

Esterification of hydroxyl-carrying polymers A) suitable. Ethercarboxylic acid B1) or ether carboxylic acid ester B2) are preferably used substoichiometrically based on the total number of hydroxyl groups, in particular in a ratio of 1: 100 to 1: 2 and especially in a ratio of 1:50 to 1: 5, for example in a ratio of 1: 20 to 1 :8th. Preference is given to

Reaction conditions thereby adjusted so that at least 10 mol%, in particular 20 to 100 mol% and especially 25 to 80 mol%, such as 30 to 70 mol% of the ether carboxylic acid used or the fatty acid ester used are reacted. In these partial esterifications very homogeneous products are formed, which manifests itself in good solubility and a sharp cloud point of aqueous solutions.

Preferably, the reaction mixture contains 5 to 98 wt .-%, particularly preferably 10 to 95 wt .-%, in particular 20 to 90 wt .-%, such as 50 to 80 wt .-% water, or 5 to 98 wt .-%, particularly preferably 10 to 95 wt .-%, in particular 20 to 90 wt .-% such as 50 to 80 wt .-% of a mixture of water and one or more water-miscible, organic solvent. In any case, water is added to the reactants A) and / or B) prior to irradiation with microwaves, so that the reaction product contains an amount of water in excess of the amount of water of reaction liberated during the esterification.

A variety of ether carboxylic acids B1) and ether carboxylic acid esters B1) is readily water-soluble, so that their implementation with hydroxyl-bearing

Polymer A) can be carried out in aqueous solution. The limited

Solubility of Various Ethercarboxylic Acids B1) and Ethercarboxylic Acid Ester B2) in Water often requires the addition of one or more water-miscible organic solvents to the reaction mixture. Preferred water-miscible organic solvents are polar protic and polar aprotic liquids. Preferably, these have a measured at 25 ° C.

Dielectric constant of at least 10 and in particular at least 12 such as at least 5. Preferred organic solvents are soluble in water to at least 100 g / l, more preferably at least 200 g / l, in particular at least 500 g / l and especially they are complete with water miscible. Particularly preferred solvents are heteroaliphatic

Compounds and in particular alcohols, ketones, end-capped polyethers, carboxylic acid amides such as tertiary carboxylic acid amides, nitriles,

Sulfoxides and sulfones. Examples of preferred aprotic solvents are formamide, Ν, Ν-dimethylformamide (DMF), Ν, Ν-dimethylacetamide, acetone, γ-butyrolactone, acetonitrile, sulfolane and dimethyl sulfoxide (DMSO). Preferred protic organic solvents are lower alcohols having 1 to 10 C atoms and in particular having 2 to 5 C atoms. Examples of suitable alcohols are

Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isoamyl alcohol, 2-methyl - 2-butanol, ethylene glycol and glycerin. Secondary and tertiary alcohols are particularly preferably used as lower alcohols, which are inert under the chosen reaction conditions and neither tend to competing esterification nor to side reactions such as dehydration. Particularly preferred secondary and tertiary alcohols having 3 to 5 C atoms such as

Isopropanol, sec-butanol, 2-pentanol and 2-methyl-2-butanol and

Neopentyl. Also mixtures of the solvents mentioned are

suitable according to the invention.

In general, low-boiling liquids are preferred as the water-miscible, organic solvents and in particular those which have a boiling point at atmospheric pressure of below 150 ° C and especially below 120 ° C such as below 100 ° C and thus with little effort again from the

Reaction products can be removed. High-boiling solvents have proven particularly useful if they are for further use of the

modified polymers may remain in the product. If water-miscible organic solvents are used, their share in the

Solvent mixture preferably between 1 and 75 wt .-%, more preferably between 2 and 60 wt .-%, in particular between 5 and 50 wt .-%, such as between 10 and 30 wt .-%. Water is contained in the solvent mixture ad 100 wt .-%.

When using ether carboxylic acids B1) or Ethercarbonsäureestem B2) with limited water solubility, one or more emulsifiers can be added to the reaction mixture in a preferred embodiment. Emulsifiers which are chemically inert towards the educts and the product are preferably used. In a particularly preferred embodiment, the emulsifier is a reaction product of separate ones

Production.

The preparation of the method used for the process according to the invention

A reaction mixture containing a hydroxyl-carrying polymer A), a

Ethercarbonsäure B1) or an Ethercarbonsäureester B2), water and optionally a water-miscible solvent and / or other auxiliaries such as emulsifier and / or catalyst, can be carried out in various ways. The mixing of polymer A) and ether carboxylic acid B1) or ether carboxylic acid ester B2) and optionally the other auxiliaries be carried out continuously, discontinuously or in semi-batch processes. In particular for processes on an industrial scale, it has proven useful to supply the starting materials to the process according to the invention in liquid form.

For this purpose, the hydroxyl-carrying polymer A) is preferably fed to the process according to the invention as a solution in water or as a solution in water and a water-miscible solvent. But it can also be used in swollen form, provided that it is pumpable.

The ether carboxylic acid B1) or the ether carboxylic acid B2), if they are liquid or at low temperatures of preferably below 150 ° C and

be melted below 100 ° C in particular, are used as such. In many cases it has been proven that B1) or B2), possibly in

molten state, mixed with water and / or a water-miscible solvent, for example, as a solution to use dispersion or emulsion.

The mixing of hydroxyl-carrying polymer A) with ether carboxylic acid B1) or ether carboxylic acid ester B2) and optionally the further auxiliaries can be carried out in a (semi) -batch process by sequential charging of the

Components are carried out, for example in a separate

Reactors. In a preferred embodiment, the ether carboxylic acid or the ether carboxylic acid ester is dissolved in a water-miscible organic solvent and then added to the already dissolved or swollen polymer. Preferably, the addition is carried out in small portions over a long time and with stirring, on the one hand to ensure a homogeneous distribution of the ether carboxylic acid or the Ethercarbonsäureesters and on the other hand, a local

Prevent precipitation of the polymer at the metering point.

In particular, for continuously carried out reactions, the starting materials in a preferred embodiment in the desired ratio of separate templates to the vessel in which the irradiation with microwaves is carried out (hereinafter also referred to as a reaction vessel) fed. In a further preferred embodiment, they are prior to entry into the reaction vessel and / or in the reaction vessel itself by means of suitable mixing elements such as static mixer and / or Archimedean screw and / or by flowing through a porous foam further homogenized. If used, a catalyst and further auxiliaries can be added to one of the educts or also to the educt mixture before it enters the reaction vessel. Solid, pulverulent and heterogeneous systems can also be reacted by the process according to the invention, with only corresponding technical devices for conveying the reaction mixture being required.

The reaction takes place according to the invention under the influence of

Microwave radiation, wherein the reaction mixture through the

Microwave radiation is preferably heated to temperatures above 110 ° C, more preferably at temperatures between 120 and 230 ° C, in particular between 130 and 210 ° C and in particular between 140 and 200 ° C such as between 150 and 195 ° C. These temperatures refer to the maximum temperatures reached during microwave irradiation. The temperature can be measured, for example, on the surface of the irradiation vessel. In continuous reactions, it is preferably determined on the reaction mixture directly after leaving the irradiation zone. The pressure in the reaction vessel is preferably set so high that the reaction mixture remains in the liquid state and does not boil. Preference is given to operating at pressures above 1 bar, preferably at pressures between 3 and 300 bar, more preferably between 5 and 200 and in particular between 10 and 100 bar, for example between 15 and 50 bar.

To accelerate or complete the reaction between polymer A) and ether carboxylic acid B1) or ether carboxylic acid ester B2), it has proven useful in many cases to work in the presence of acidic catalysts.

Preferred catalysts according to the invention are acidic inorganic,

organometallic or organic catalysts and mixtures of several these catalysts. Preferred catalysts are liquid and / or im

Reaction medium soluble.

Examples of acidic inorganic catalysts for the purposes of the present invention are sulfuric acid, phosphoric acid, phosphonic acid, hypophosphorous acid, aluminum sulfate hydrate, alum, acidic silica gel and acid

To call aluminum hydroxide. Furthermore, for example

Aluminum compounds of the general formula Al (OR ¹⁵ ) ₃ and titanates of the general formula Ti (OR ¹⁵ ) ₄ can be used as acidic inorganic catalysts, where the radicals R ^{15 can} each be identical or different and are selected independently of one another from C 1 -C 10. Alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, iso-amyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexy, n-nonyl or n-decyl, C3-C12-cycloalkyl radicals, for example cyclopropyl, cyclobutyl, Cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; preferred are cyclopentyl, cyclohexyl and cycloheptyl. The radicals R ¹⁵ in Al (OR ¹⁵ ) ₃ or Ti (OR ⁵ ) 4 are preferably identical and selected from isopropyl, butyl and 2-ethylhexyl.

Preferred acidic organometallic catalysts are, for example, selected from dialkyltin oxides (R ¹⁵ ) ₂ SnO, where R ^{15 is} as defined above. A particularly preferred representative of acidic organometallic catalysts is di-n-butyltin oxide, which is commercially available as so-called oxo-tin or Fascat® grades.

Preferred acidic organic catalysts are acidic organic compounds with, for example, sulfonic acid or phosphonic acid groups. Particularly preferred sulfonic acids contain at least one sulfonic acid group and at least one saturated or unsaturated, linear, branched and / or cyclic hydrocarbon radical having 1 to 40 carbon atoms and preferably having 3 to 24 carbon atoms. Particularly preferred are aromatic sulfonic acids and especially alkylaromatic mono-sulfonic acids with one or more CrC ₂ 8-alkyl radicals and in particular those having C ₃ -C ₂ 2-alkyl radicals. Suitable examples are methanesulfonic acid, butanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, 2-mesitylenesulfonic acid,

4-ethylbenzenesulfonic acid, isopropylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid; dodecylbenzenesulfonic

Didodecylbenzenesulfonic acid, naphthalenesulfonic acid. Also acid

Ion exchangers can be used as acidic organic catalysts, for example, crosslinked poly (styrene) resins carrying sulfonic acid groups. Particularly preferred for carrying out the process according to the invention are sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid,

Dodecylbenzenesulfonic acid, phosphoric acid, polyphosphoric acid and

Polystyrenesulfonic. Especially preferred are titanates of the general formula Ti (OR ¹⁵ ) ₄ and especially titanium tetrabutylate and titanium tetraisopropylate.

If you want acidic inorganic, organometallic or organic

Catalysts are used according to the invention 0.01 to 10 wt .-%, preferably 0.02 to 2 wt .-% catalyst. In a further preferred embodiment, the microwave irradiation is carried out in the presence of acidic, solid and in the reaction medium not or not completely soluble catalysts. Such heterogeneous

Catalysts can be suspended in the reaction mixture and exposed to microwave irradiation together with the reaction mixture. In a particularly preferred continuous embodiment, the

optionally mixed with solvent reaction mixture over an im

Reaction vessel and fixed in particular in the irradiation zone

Passed fixed bed catalyst while exposed to microwave radiation. Suitable solid catalysts are, for example, zeolites, silica gel, montmorillonite and (partially) crosslinked polystyrenesulphonic acid, which may optionally be impregnated with catalytically active metal salts. Suitable acid ion exchangers based on polystyrenesulfonic acids, which are used as solid phase catalysts can be obtained for example from Rohm & Haas under the trade name Amberlyst ^®.

To accelerate or to complete the reaction between polymer A) and ether carboxylic acid ester B2), it has proven useful in many cases

Presence of basic catalysts or mixtures of several of these catalysts work. As basic catalysts are in the context of the present invention quite generally such basic compounds

used, which are suitable to accelerate the transesterification of Ethercarbonsäureestern with alcohols. Examples of suitable catalysts are

inorganic and organic bases such as metal hydroxides, oxides, carbonates or alkoxides. In a preferred embodiment, the basic catalyst is selected from the group of hydroxides, oxides,

Carbonates or alkoxides of alkali or alkaline earth metals. There are

Lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methoxide,

Potassium methoxide, sodium carbonate and potassium carbonate are very particularly preferred. Cyanide ions are also suitable as catalyst. These substances can be used in solid form or as a solution, for example as an aqueous or alcoholic solution. The amount of catalysts used depends on the activity and stability of the catalyst in the selected

Reaction conditions and must be adapted to the particular reaction. The amount of catalyst to be used can vary within wide limits.

Particular preference is given to using catalytic amounts of the abovementioned reaction-accelerating compounds, preferably im

Range between 0.001 and 10 wt .-%, particularly preferably in the range of 0.01 to 5 wt .-%, such as between 0.02 and 2 wt .-%, based on the amount of ether carboxylic acid B2).

After microwave irradiation, the reaction mixture can in many cases be fed directly to another use. In order to obtain solvent-free products, water optionally present organic solvent can be separated from the crude product by conventional separation methods such as phase separation, distillation, freeze-drying or absorption. there can also be used in excess educts and optionally unreacted residual amounts of the reactants are separated with. For special

Demands, the crude products by conventional purification methods such as washing, reprecipitation, filtration or chromatographic

Procedure be further purified. Often, it has also proved to be successful here to neutralize excess or unreacted ether carboxylic acid and remove by washing.

The microwave irradiation is usually carried out in devices which have a reaction vessel (also referred to below as irradiation vessel) made of a material that is largely transparent to microwaves, into which microwave radiation generated in a microwave generator is coupled. Microwave generators, such as the magnetron, the klystron and the gyrotron are known in the art.

The used for carrying out the method according to the invention

Reaction vessels are preferably made of largely microwave-transparent, high-melting material or contain at least parts such as

for example, windows made of these materials. Non-metallic reaction vessels are particularly preferably used. Under largely

Microwave transparent here materials understood that absorb as little microwave energy and convert it into heat. As a measure of the ability of a substance to absorb microwave energy and convert it into heat, the dielectric loss factor tan δ = ε ^' Ίε ^' is often used ^.

used. The dielectric loss factor tan δ is defined as the ratio of dielectric loss ε "and ε dielectric constant ^'. Examples of tan δ values of different materials are, for example, in D. Bogdal,

Microwave-assisted Organic Synthesis, Elsevier 2005. For reaction vessels suitable according to the invention, materials with tan δ values measured at 2.45 GHz and 25 ° C. of less than 0.01, in particular less than 0.005 and especially less than 0.001 are preferred. As a preferred microwave-transparent and temperature-stable materials come primarily materials based on minerals such as quartz, alumina, zirconia, silicon nitride and similar consideration. Also thermally stable plastics such as in particular fluoropolymers such as Teflon, and engineering plastics such

Polypropylene, or polyaryletherketones such as glass fiber reinforced polyetheretherketone (PEEK) are suitable as vessel materials. To the

In order to withstand temperature conditions during the reaction, in particular minerals coated with these plastics, such as quartz or aluminum oxide, have proven to be useful as vessel materials.

Microwaves are electromagnetic waves having a wavelength between about 1 cm and 1 m and frequencies between about 300 MHz and 30 GHz. This frequency range is in principle for the

inventive method suitable. For the inventive method, microwave radiation with frequencies released for industrial, scientific and medical applications is preferably used, such as

for example, at frequencies of 915 MHz, 2.45 GHz, 5.8 GHz or 24.12 GHz. The microwave irradiation of the reaction mixture can be carried out both in

Microwave applicators that operate in mono or quasi-single mode as well as in those working in multimode done. Corresponding devices are known to the person skilled in the art.

The for carrying out the method according to the invention in the

The reaction vessel to be irradiated microwave power is particularly dependent on the desired reaction temperature, the geometry of the reaction vessel and the associated reaction volume as well as in continuously carried out reactions of the flow rate of the

Reaction good through the reaction vessel. It is usually between 100 W and several 100 kW and in particular between 200 W and 100 kW such as between 500 W and 70 kW. It can be applied at one or more points of the reaction vessel. It can be generated by one or more microwave generators.

The duration of the microwave irradiation depends on various factors such as the reaction volume, the geometry of the reaction vessel, the desired Residence time of the reaction mixture at the reaction temperature and the desired degree of conversion. Usually, the microwave irradiation for a period of less than 30 minutes, preferably between

0.01 second and 15 minutes, more preferably between 0.1 second and 10 minutes and in particular between one second and 5 minutes, for example between 5 seconds and 2 minutes. The intensity (power) of the microwave radiation is adjusted so that the

Reactive material in the shortest possible time reaches the desired reaction temperature. In a further preferred embodiment of the process according to the invention, it has proven useful to supply the reaction mixture to the reaction vessel in heated form. This lowers the viscosity of the reaction mixture and improves its homogeneity. To maintain the

Reaction temperature, the reaction mixture with reduced and / or pulsed power can be further irradiated or otherwise maintained at temperature. In a preferred embodiment, the reaction product is cooled as soon as possible after completion of the microwave irradiation to temperatures below 100 ° C, preferably below 80 ° C and especially below 50 ° C. The microwave irradiation can be carried out batchwise or, preferably, continuously, for example in a flow tube serving as a reaction vessel, which is also referred to below as the reaction tube. You can continue in semi-batch processes like

For example, continuously operated stirred reactors or cascade reactors are performed. In a preferred embodiment, the reaction is carried out in a closed, pressure-resistant and chemically inert vessel, wherein the water and optionally the educts lead to a pressure build-up. After completion of the reaction, the excess pressure can be used by venting to volatilize and separate water and optionally excess acid and / or cooling of the reaction product. In a particularly preferred embodiment, the reaction mixture after completion of the microwave irradiation or after leaving the reaction vessel as quickly as possible of water and optionally present catalytically active Species freed to avoid hydrolysis of the ester formed.

In a preferred embodiment, the process according to the invention is carried out in a discontinuous microwave reactor in which a certain amount of the reaction mixture is filled into an irradiation vessel, irradiated with microwaves and subsequently worked up. Here is the

Microwave irradiation is preferably carried out in a pressure-tight, stirred vessel. The coupling of the microwaves in the reaction vessel can, if the reaction vessel is made of a microwave transparent material or has transparent windows for microwave over the

Vascular wall done. The microwaves can also be coupled via antennas, probes or waveguide systems in the reaction vessel. For the irradiation of larger reaction volumes, a multimode microwave applicator is preferably used here. The discontinuous

Embodiment of the method according to the invention allows by varying the microwave power fast as well as slow heating rates and in particular holding the temperature for longer periods such as several hours. In a preferred embodiment, the aqueous

Provided reaction mixture before starting the microwave irradiation in the irradiation vessel. It preferably has temperatures below 100 ° C as

for example between 10 and 50 ° C. In a further preferred

Embodiment, the reactants and water or parts thereof are supplied to the irradiation vessel only during the irradiation with microwaves. In a further preferred embodiment, the discontinuous

Microwave reactor with continuous feeding of educts and

operated simultaneously discharging reaction mixture in the form of a semi-batch or cascade reactor.

In a particularly preferred embodiment, the process according to the invention is carried out in a continuous microwave reactor. The

Reaction mixture is to continuously by a pressure-resistant, inert to the reactants, for microwave largely transparent and built into a microwave applicator, serving as an irradiation vessel Reaction tube out. This reaction tube preferably has a diameter of one millimeter to about 50 cm, especially between 2 mm and 35 cm, for example between 5 mm and 15 cm. Particularly preferred is the

Diameter of the reaction tube smaller than the penetration depth of the microwaves in the reaction mixture to be irradiated. In particular, it is 1 to 70% and especially 5 to 60% such as 10 to 50% of the penetration depth. Under penetration depth is understood here the route on which the irradiated

Microwave energy is attenuated to 1 / e. Reaction or flow tubes are here understood to be irradiation vessels in which the ratio of length to diameter of the

Irradiation zone (this is understood as the proportion of the flow tube in which the reaction mixture is exposed to microwave radiation) greater than 5, preferably between 10 and 100,000, more preferably between 20 and 10,000 such as between 30 and 1,000. For example, they can be straight or bent or shaped as a tube coil. In a specific embodiment, the reaction tube is in the form of a

Double jacket tube designed by the inner and outer space, the reaction mixture can be performed sequentially in countercurrent, for example, to increase the temperature control and energy efficiency of the process. The length of the reaction tube is to be understood as meaning the total distance traveled by the reaction mixture in the microwave field. The reaction tube is at least one, but preferably several, such as two, three, four, five, six, seven, eight or more in length

Surrounded by microwave heaters. The microwave radiation preferably takes place via the tube jacket. In a further preferred embodiment, the microwave irradiation takes place by means of at least one antenna via the tube ends.

The reaction tube is usually at the inlet with a metering pump and a pressure gauge and at the outlet with a pressure holding valve and a

Heat exchanger provided. Preferably, the reaction mixture is the

Reaction tube in liquid form with temperatures below 100 ° C as

for example, supplied between 10 ° C and 90 ° C. In a further preferred Embodiment, a solution of the polymer and carboxylic acid or carboxylic acid ester only shortly before entering the reaction tube, optionally mixed with the aid of suitable mixing elements such as static mixer and / or Archimedean screw and / or by flowing through a porous foam. In a further preferred embodiment, they are in the reaction tube by means of suitable mixing elements such

For example, static mixer and / or Archimedean screw and / or further homogenized by flowing through a porous foam. By varying the tube cross-section, length of the irradiation zone,

Flow rate, geometry of the microwave radiator, the irradiated microwave power and the temperature reached thereby are the

Reaction conditions adjusted so that the maximum reaction temperature is reached as quickly as possible. In a preferred embodiment, the residence time at maximum temperature is chosen so short that as few side or subsequent reactions occur as possible.

The continuous microwave reactor is preferably operated in monomode or quasi-monomode. The residence time of the reaction mixture in the irradiation zone is generally less than 20 minutes, preferably between 0.01 second and 10 minutes, preferably between 0.1 second and 5 minutes

for example, between one second and 3 minutes. The reaction mixture can flow through the irradiation zone several times to complete the reaction, optionally after intermediate cooling.

In a particularly preferred embodiment, the irradiation of the reaction material with microwaves is carried out in a reaction tube whose longitudinal axis is in the direction of propagation of the microwaves in a monomode microwave applicator. Preferably, the length of the

Irradiation zone at least half the wavelength, more preferably at least one and up to 20 times, especially 2 to 15 times, for example, 3 to 10 times the wavelength of the used

Microwave radiation. With this geometry, energy can be made up of several For example, two, three, four, five, six or more successive maxima of the propagating parallel to the longitudinal axis of the tube microwave are transferred to the reaction mixture, which significantly improves the energy efficiency of the process.

The irradiation of the reaction product with microwaves preferably takes place in a substantially microwave-transparent straight reaction tube, which is located within a hollow conductor connected to a microwave generator and functioning as a microwave applicator. Preferably, the reaction tube is aligned axially with a central axis of symmetry of this waveguide. The waveguide is preferably formed as a cavity resonator. Preferably, the length of the

Cavity resonator dimensioned so that it forms a standing wave. Further preferred are those not absorbed in the waveguide

Microwaves reflected at its end. By molding the

Mikrowellenapplikators as a resonator of the reflection type, a local increase in the electric field strength are achieved with the same power supplied by the generator and increased energy utilization.

The cavity resonator is preferably operated in the Eoi _n mode, where n stands for an integer and indicates the number of field maxima of the microwave along the central axis of symmetry of the resonator. In this operation, the electric field is in the direction of the central axis of symmetry of the

Cavity resonator directed. It has a maximum in the area of the central axis of symmetry and decreases to the lateral surface to the value zero. These

Field configuration is rotationally symmetrical about the central axis of symmetry. By using a cavity resonator having a length where n is an integer, the formation of a standing wave is enabled. Depending on the desired flow rate of the reaction mixture through the

Reaction tube, the required temperature and the required residence time in the resonator, the length of the resonator is selected relative to the wavelength of the microwave radiation used. N is preferably an integer from 1 to 200, particularly preferably from 2 to 100, in particular from 3 to 50 specifically from 4 to 20 such as three, four, five, six, seven, eight, nine or ten.

The eoin mode of the cavity resonator is also known in English as

TMoin mode (transversal magnetic), see, for example, K. Lange, K.H. Löcherer, Taschenbuch der Hochfrequenztechnik ", volume 2, page K21 ff.

The irradiation of the microwave energy into the waveguide acting as a microwave applicator can take place via suitably dimensioned holes or slots. In a specific embodiment of the method according to the invention, the irradiation of the reaction material with microwaves in a reaction tube, which is located in a waveguide with coaxial transition of the microwaves. For this method, particularly preferred microwave devices are from a cavity resonator, a coupling device for coupling a

Microwave field in the cavity resonator and constructed with one opening at two opposite end walls for passing the reaction tube through the resonator. The coupling of the microwaves in the

Cavity resonator is preferably via a coupling pin, in the

Cavity resonator protrudes. Preferably, the coupling pin is as a

Forming coupling antenna, preferably formed metallic inner conductor tube. In a particularly preferred embodiment, this protrudes

Coupling pin through one of the frontal openings in the cavity resonator inside. Particularly preferably, the reaction tube connects to the

Inner conductor tube of the coaxial transition and in particular it is guided through the cavity into the cavity resonator. Preferably, this is flushed

Reaction tube axially with a central axis of symmetry of the cavity resonator, to which the cavity resonator preferably each having a central opening on two opposite end walls for passing the reaction tube.

The feeding of the microwaves in the coupling pin or in as

Coupling antenna acting inner conductor tube can be done for example by means of a coaxial connecting cable. In a preferred embodiment the microwave field is supplied via a waveguide to the resonator, wherein the protruding from the cavity resonator end of the coupling pin in a

Opening, which is located in the wall of the waveguide, in the waveguide

is guided in and removes microwave energy from the waveguide and coupled into the resonator.

In a specific embodiment, the irradiation of the reaction mixture with microwaves in a microwave-transparent reaction tube, which takes place

is axially symmetrical in a Eoi _n round waveguide with coaxial transition of the microwaves. In this case, the reaction tube is guided through the cavity of an inner conductor tube acting as a coupling antenna into the cavity resonator. In a further preferred embodiment, the irradiation of the salt with microwaves in a microwave transparent reaction tube which _n cavity resonator with the axial feed of the microwave is passed through a E ₀ i, whereby the length of the cavity resonator is dimensioned in such a way that n = 2 or more Form field maxima of the microwave. In a further preferred embodiment, the irradiation of the reaction mixture with microwaves in a microwave-transparent reaction tube, which is guided by a Eoi _n- cavity resonator with axial feeding of the microwaves, wherein the length of the cavity resonator is dimensioned so that a standing wave with n = 2 or more field maxima of the microwave is formed. In a further preferred embodiment, the irradiation of the Reaktionsgut with microwaves in a microwave-transparent reaction tube, which is axially symmetrical in a circular cylindrical eoin cavity resonator with coaxial transition of the microwaves, wherein the length of the

Cavity resonator is dimensioned so that form n = 2 or more field maxima of the microwave. In a further preferred embodiment, the irradiation of the reaction mixture with microwaves takes place in one

Microwave-transparent reaction tube, which is axially symmetrical in a circular cylindrical eoin cavity resonator with coaxial transition

Microwave is located, wherein the length of the cavity is dimensioned so that forms a standing wave with n = 2 or more field maxima of the microwave. Particularly suitable for the process according to the invention

Eor cavity resonators preferably have a diameter that corresponds to at least half the wavelength of the microwave radiation used.

Preferably, the diameter of the cavity resonator is the 1, 0- to

10 times, more preferably 1, 1 to 5 times and especially 2.1 to 2.6 times the half wavelength of the microwave radiation used.

Preferably, the Eoi cavity resonator has a round cross-section, which is also referred to as EorRundhohlleiter. Particularly preferably it has a cylindrical shape and especially a circular cylindrical shape.

When the process according to the invention is carried out continuously, the reaction mixture is often not yet in chemical equilibrium when leaving the irradiation zone. In a preferred embodiment, therefore, after passing through the irradiation zone, the reaction mixture is transferred directly, that is to say without intermediate cooling, into an isothermal reaction zone in which it is kept at the reaction temperature for a certain time. Only after leaving the isothermal reaction zone, the reaction mixture is optionally relaxed and cooled. The direct transfer from the irradiation zone into the isothermal reaction zone is to be understood as meaning that no active measures are taken between the irradiation zone and the isothermal reaction zone for supplying and in particular for dissipating heat. Preferably, the temperature difference between leaving the

Irradiation zone to the entry into the isothermal reaction path less than ± 30 ° C, preferably less than ± 20 ° C, more preferably less than ± 10 ° C and especially less than ± 5 ° C. In a specific embodiment, the temperature of the reaction product when entering the isothermal reaction path corresponds to the temperature when leaving the irradiation zone. This embodiment allows rapid and targeted heating of the reaction mixture to the desired reaction temperature without partial overheating and then a

Linger at this reaction temperature for a defined period of time. In this embodiment, the reaction mixture is preferably directly after leaving the Isothermal reaction path as soon as possible cooled to temperatures below 120 ° C, preferably below 100 ° C and especially below 60 ° C.

As an isothermal reaction path all chemically inert vessels come in

Consider that a lingering of the reaction mixture in the in the

Allow irradiation zone set temperature. Isothermal reaction zone is understood to mean that the temperature of the reaction mixture in the isothermal reaction zone is kept constant with respect to the inlet temperature at ± 30 ° C., preferably ± 20 ° C., more preferably ± 10 ° C. and in particular ± 5 ° C. Thus, when leaving the isothermal reaction zone, the reaction mixture has a temperature which deviates at most ± 30 ° C., preferably ± 20 ° C., more preferably ± 10 ° C. and in particular ± 5 ° C. from the temperature on entry into the isothermal reaction zone. In addition to continuously operated Rührbehältem and container cascades pipes are particularly suitable as an isothermal reaction zone. These

Reaction paths may consist of various materials such as metals, ceramics, glass, quartz or plastics, provided that they are mechanically stable and chemically inert under the selected temperature and pressure conditions. Thermally insulated vessels have proven to be particularly useful. The residence time of the reaction mixture in the isothermal

Reaction distance can, for example, the volume of the isothermal

Reaction distance are set. When using stirred containers and container cascades, it has proven equally appropriate to adjust the residence time on the degree of filling of the container. In a preferred embodiment, the isothermal reaction zone is with active or passive mixing elements

equipped.

In a preferred embodiment, a tube is used as the isothermal reaction section. This may be an extension of the

Microwave-transparent reaction tube after the irradiation zone or even a separate, related to the reaction tube tube of the same or different material act. About the length of the Pipe and / or its cross-section can be at a given flow rate the

Determine the residence time of the reaction mixture. The tube acting as an isothermal reaction section is thermally insulated in the simplest case, so that the temperature prevailing when the reaction mixture enters the isothermal reaction section is kept within the limits given above. The reaction mixture can in the isothermal reaction zone but also for example by means of a

Heat transfer medium or cooling medium targeted energy to be added or removed. This embodiment has proven particularly suitable for starting the device or the method. Thus, the isothermal reaction path can be configured for example as a tube coil or as a tube bundle, which is located in a heating or cooling bath or acted upon in the form of a double-walled tube with a heating or cooling medium. The isothermal reaction zone can also be located in a further microwave applicator in which the reaction mixture is again treated with microwaves. Both single-mode and multi-mode applicators can be used.

The residence time of the reaction mixture in the isothermal reaction zone is preferably selected such that the thermal equilibrium state defined by the prevailing conditions is achieved. Usually that is

Dwell time between 1 second and 10 hours, preferably between

10 seconds and 2 hours, more preferably between 20 seconds and 60 minutes, such as between 30 seconds and 30 minutes. Further preferably, the ratio between residence time of the reaction mixture in the isothermal reaction zone to the residence time in the irradiation zone between 1: 2 and 100: 1, more preferably 1: 1 to 50: 1 and in particular between 1: 1, 5 and 10: 1.

In order to achieve particularly high degrees of conversion, it has proven useful in many cases to suspend the reaction product obtained again from microwave irradiation, it being possible for the ratio of the reactants used to be supplemented by consumed or deficient starting materials.

The process according to the invention allows polymer-analogous modification Hydroxyl-bearing polymers and in particular of polyvinyl alcohol with ether carboxylic acids or ether carboxylic acid esters in continuous or discontinuous processes and thus in industrially interesting amounts. In addition to water or lower alcohol there are no by-products to be disposed of and polluting the environment. A further advantage of the process according to the invention lies in the surprising observation that the polymer-analogous condensation reactions can be carried out in aqueous solution since water is the most suitable polymer bearing hydroxyl groups

Solvent is and is also beneficial in ecological terms. The addition of certain polar organic solvents can counteract any increase in viscosity occurring during the course of the process and facilitate the reaction with less water-soluble ether carboxylic acids or their esters. In particular, the process according to the invention is suitable for partial esterifications of hydroxyl-carrying polymers, since the reaction mixtures, despite differences in viscosity between

Hydroxyl-carrying polymers A) and ether carboxylic acids B1) or

Ethercarbonsäureestern B2) to a homogeneous distribution of

Ethercarbonsäurereste lead over the entire chain length of the polymer. The process according to the invention permits reproducible production along its chain length of statistically modified products. The variety of available for the process according to the invention in technical quantities

Ether carboxylic acids and ether carboxylic acid esters opens up a wide range of modification possibilities. By the method according to the invention can be selected by suitable choice of the ether carboxylic acid, for example, the swelling behavior, the solubility in water or organic solvents, the adhesion to different polar substrates, the mechanical strength and the

specifically modify the thermal stability of the polymers. Thus, by reaction with ether carboxylic acids or esters thereof, the water solubility of the polymers is further improved, especially in cold water. At the same time the elasticity and thus the ductility of the polymers is significantly increased without their

Solution viscosity appreciably increases and they can thus be applied according to established methods The method according to the invention

Modified polymers are versatile as for example as Fibers, adhesives, emulsifiers, lamination for safety glass and plastics, paper coating, thickeners for latices, binders for fertilizers, as water-soluble as well as water-insoluble films such as

self-dissolving packaging films, as an additive to inks and concrete as well as a temporary, water-removable surface protection suitable.

Examples The discontinuous microwave irradiation was carried out in a single mode

Microwave reactor "initiator ^®" by the company Biotage at a frequency of 2.45 GHz. The temperature was measured with an IR sensor. As

Reaction vessels were closed, pressure-resistant glass cuvettes (pressure vials) with a volume of 20 ml, in which was homogenized with magnetic stirring.

The microwave power was adjusted over the experimental period in each case in such a way that the desired temperature of the reaction mixture was reached as quickly as possible and then kept constant over the period specified in the experiment descriptions. After completion of the

Microwave irradiation, the glass cuvette was cooled with compressed air.

Continuous irradiation of the reaction mixtures with microwaves was carried out in a reaction tube (60 × 1 cm) made of aluminum oxide, which was axially symmetric in a cylindrical cavity resonator (60 × 10 cm). At one of the end faces of the cavity resonator, the reaction tube passed through the

Cavity of a functioning as a coupling antenna inner conductor tube. The microwave field generated by a magnetron with a frequency of 2.45 GHz was coupled by means of the coupling antenna in the cavity resonator (Eoi cavity applicator, single mode), in which a standing wave

trained. When an isothermal reaction section was used, the heated reaction mixtures were conveyed immediately after leaving the reaction tube through a thermally insulated stainless steel tube (3.0 m × 1 cm, unless stated otherwise). After leaving the reaction tube or when using the isothermal reaction path after leaving the same were the

Reaction mixtures relaxed to atmospheric pressure, immediately by means of a

Intensive heat exchanger cooled to the specified temperature. The microwave power was adjusted over the duration of the experiment in each case in such a way that the desired temperature of the reaction mixture was kept constant at the end of the irradiation zone. The microwave powers mentioned in the test descriptions therefore represent the time average of the irradiated microwave power. The temperature measurement of the

Reaction mixture was made directly after leaving the irradiation zone by means of Pt100 temperature sensor. Microwave energy not directly absorbed by the reaction mixture was reflected at the end face of the cavity resonator opposite the coupling antenna; the ones from

Reaction mixture also not absorbed in the return and mirrored back in the direction of the magnetron microwave energy was using a

Prism system (circulator) passed into a water-containing vessel. Using a high-pressure pump and a pressure relief valve, the reaction mixture was placed in the reaction tube under such a working pressure that was sufficient to all educts and products or condensation products always in the liquid state from the difference between radiated energy and heating of this water load to keep. The reaction mixtures were pumped through the device at a constant flow rate and the residence time in the reaction tube was adjusted by modifying the flow rate.

The analysis of the reaction products was carried out by means of ¹ H-NMR spectroscopy at 500 MHz in CDCl ₃ . Example 1: Continuous esterification of poly (vinyl alcohol) Mowiol 4-98 with 3,6,9-trioxodecanoic acid

In a 10 l Büchi stirred autoclave with gas inlet tube, stirrer,

Internal thermometer and pressure compensation became a solution of 1, 5 kg

Polyvinyl alcohol (Mowiol ^® 4-98, molecular weight 27,000 g / mol;

Degree of hydrolysis 98%) in 6 kg of water, treated with 18 g of p-toluenesulfonic acid and heated to 40 ° C. At this temperature, over a period of one hour with stirring, a solution of 0.3 kg of 3,6,9-trioxodecanoic acid (1.6 mol) in 1 kg of isopropanol was added.

The reaction mixture thus obtained was continuously pumped at a working pressure of 35 bar at 5 l / h through the reaction tube and a

2.2 kW of microwave power was expended, of which 92% was absorbed by the reaction mixture. The residence time of the reaction mixture in the

Irradiation zone was about 48 seconds. When leaving the irradiation zone, the reaction mixture had a temperature of 205 ° C and was transferred directly at this temperature in the isothermal reaction zone. At the end of the isothermal reaction zone, the reaction mixture had a temperature of 186 ° C. The reaction mixture was cooled to room temperature immediately after leaving the isothermal reaction section and adjusted to pH 4 with bicarbonate solution.

The reaction product was a homogeneous, slightly yellowish, low viscosity solution. After evaporation of the solvent resulted in a viscous mass, the IR spectrum for esters of polyvinyl alcohol characteristic bands at 1735 cm ^"1 and 1245 cm ^{" 1 shows} with respect to the polyvinyl alcohol significantly increased intensity. Example 2: Continuous esterification of poly (vinyl alcohol) Mowior 8-88 with 3,6,9-trioxodecanoic acid

In a 10 l Büchi stirred autoclave with gas inlet tube, stirrer,

Internal thermometer and pressure equalization became a solution of 0.7. kg

Polyvinyl alcohol (Mowiol ^® 8-88, molecular weight 67,000 g / mol, degree of hydrolysis 88%) presented in 7 kg of water, treated with 10 g of p-toluenesulfonic acid and heated to 60 ° C. At this temperature, over a period of one hour with stirring, a solution of 600 g of 3,6,9-trioxodecanoic acid (3.2 mol) in 500 g of isopropanol was added.

Subjected to microwave power of 2.3 kW, of which 90% were absorbed by the reaction mixture. The residence time of the reaction mixture in the

Irradiation zone was about 48 seconds. When leaving the irradiation zone, the reaction mixture had a temperature of 203 ° C. It was cooled to room temperature immediately after leaving the reaction zone and with

Hydrogen carbonate solution adjusted to pH 4.

The reaction product was a homogeneous, colorless solution with lower

Viscosity. After evaporation of the solvent resulted in a viscous mass whose IR spectrum for esters of polyvinyl alcohol at characteristic bands

1735 cm ^"1 and 1245 cm ^{" 1} with a significantly increased compared to the polyvinyl alcohol used.

Example 3: Continuous esterification of poly (vinyl alcohol Mowiol ^® 4-98 with oleic acid + 8 moles of EO-carboxylic acid

In a 10 1 Büchi stirred autoclave with gas inlet tube, stirrer,

Internal thermometer and pressure equalization became a solution of 1.kg

Polyvinyl alcohol (Mowiol ^® 4-98, molecular weight 27,000 g / mol; degree of hydrolysis 98%) in 5 kg of water, treated with 20 g of p-toluenesulfonic acid and heated to 55 ° C. At this temperature, over a period of one hour with stirring, a solution of 900 g (1, 5 mol) of oleic acid +

8 EO carboxylic acid (prepared by ethoxylation of oleic acid with 8 mol

Ethylene oxide and subsequent reaction with sodium chloroacetate) in 2 kg

Isopropanol added.

The resulting reaction mixture was pumped continuously at 4.5 l / h through the reaction tube at a working pressure of 32 bar and a

Microwave power of 2.0 kW exposed, of which 91% were absorbed by the reaction mixture. The residence time of the reaction mixture in the

Irradiation zone was about 52 seconds. When leaving the irradiation zone, the reaction mixture had a temperature of 205 ° C and was transferred directly at this temperature in the isothermal reaction zone. At the end of the isothermal reaction zone, the reaction mixture had a temperature of 189.degree. The reaction mixture was adjusted to pH 4 directly after leaving the reaction zone to room temperature with bicarbonate solution.

The reaction product was a homogeneous, colorless solution with lower

1735 cm ^"1 and 1245 cm ^{" 1} shows. The hydrophobic character of the polymer due to the alkyl radical of the ether carboxylic acid was manifested by a lower hygroscopicity of the polymer surface. Furthermore, a slight haze of the film indicates the formation of hydrophobic domains in the polymer.

To characterize the properties of the modified polymers, the following methods were used:

Method 1) Preparation of a Polymer Solution:

500 ml of demineralized water are heated to 90 ° C and then slowly the required amount of modified polymer with constant stirring sprinkled so that no lumps form and a clear solution is formed. After cooling, the volume shrunk by evaporation is made up to the nearest 500 ml with demineralised water. Method 2) Preparation of a polymer film:

100 ml of a 6% strength by weight polymer solution (6% strength by weight with respect to solids content) are poured onto a commercial film casting plate and the solution is dried for 2 to 3 days in air at room temperature. Films used to determine film solubility are additionally dyed with Patent Blue V solution (10 ml per 100 ml of polymer solution).

Method 3) Determination of the Film Solubility:

From a polymer film prepared as described above, an approximately 2 x 2 cm piece is cut out and this clamped in a frame. The frame is hung in the solvent to be tested at the temperature to be tested (for example, water at 80 ° C) and the solvent is stirred slowly. The time to complete dissolution of the film is measured. If the film is not completely dissolved after 600 s (= 10 min), the film is referred to as "insoluble", otherwise the time until complete dissolution is noted.

Method 4) Determination of the Mechanical Properties of the Polymer Films: From a polymer film prepared as described above (without the addition of Patent Blue V solution), a piece about 10 × 2 cm in size is cut out and subjected to a tensile elongation experiment using a commercially available apparatus. The tensile strength indicates the maximum force that will withstand the film until it breaks.

Method 5) Determination of the viscosity of polymer solutions:

According to the method for the preparation of polymer solutions described above, a 4 wt .-% polymer solution (in terms of dry content) is prepared and determined its viscosity at 20 ° C with a commercial Brookfield viscometer at 20 revolutions per minute (rpm). The choice of a suitable spindle is made depending on the viscosity of the solution. The following data were determined for these polyvinyl alcohols and the modified polymers using these methods:

The modified polymers show markedly improved solubility in water at 20 ° C as well as at 80 ° C compared to the underlying poly (vinyl alcohols). While the unmodified poly (vinyl alcohols) in

Room temperature (20 ° C) are not soluble at all, the modified polymers dissolve completely within 3 minutes. At both temperatures there is no evidence of the presence of polymer components with dissimilar solubility. The modified films have at one compared to known

Polyvinyl alcohols comparable tensile strength significantly improved

Elasticity (increased breaking strength) and thus increased elasticity with slightly increased tensile strength. However, the solution viscosity of the polymers remains largely unchanged by the modification, so that the modified polymers can be applied as standard products.

Claims

claims:

1. esters of hydroxyl-bearing polymers containing repetitive structural units of the formulas (I) and (II) in block, alternating or random sequence

wherein

D represents a direct bond between the polymer backbone and hydroxyl group, a C to C ₆ alkylene group, a C ₅ - to C ₂ arylene group, an oxyalkylene group of the formula -OR ² -, a Estergruppe of the formula -C (O) -OR ² - or an amide group of the formula -C (O) -N (R ³ ) R ² -, E for a hydrocarbon radical having 1 to 10 C atoms

R ^{1 is} hydrogen, a hydrocarbon radical having 1 to 50 carbon atoms or an acyl radical of the formula -C (O) -R ⁴

R ^{2 is} a C ₂ - to Cio-alkylene radical,

R ^{3 is} hydrogen or a C ¹ -C 10 -alkyl radical which may carry substituents,

R ^{4 is} a hydrocarbon radical having 1 to 50 C atoms,

A is a C ₂ - to C 10 -alkylene radical,

k for a number between 1 and 100,

n for a number from 0 to 4999,

m for a number from 1 to 5000,

n + m is a number from 10 to 5,000, with the proviso that a) the molar fraction of the structural units (I) on the polymer is between 0 and 99.9 mol%, and b) the molar fraction of the structural units (II) on the polymer is between 0.1 and 100 mol% of the repetitive units.

2. esters of hydroxyl-carrying polymers according to claim 1, wherein the polymer in addition to the structural units of the formulas (I) and (II) additionally comprises structural units derived from other ethylenically unsaturated monomers.

3. esters of hydroxyl-carrying polymers according to claim 1 and / or 2, in which derive the structural units of the formula (I) derived from vinyl alcohol.

4. esters of hydroxyl-bearing polymers according to one or more of claims 2 and / or 3, wherein the polymer in addition to the structural units of the formulas (I) and (II) also comprises vinyl acetate derived structural units.

5. Ester of hydroxyl-bearing polymers according to one or more of claims 1 to 4, wherein R ^{1 is} a hydrocarbon radical having 2 to

20 C atoms stands.

6. Ester of hydroxyl-bearing polymers according to one or more of claims 1 to 4, wherein R ^{1 is} an acyl radical of the formula -C (0) -R ⁴ having 2 to 20 carbon atoms.

7. Ester of hydroxyl-carrying polymers according to one or more of claims 1 to 6, wherein E is a methyl group.

8th . Ester of hydroxyl-carrying polymers according to one or more of claims 1 to 7, wherein A is an alkylene radical having 2 or 3 carbon atoms.

9. A process for the preparation of esters of hydroxyl-bearing polymers containing repetitive structural units of the formulas (I) and (II) in block, alternating or random sequence wherein

D for a direct bond between polymer backbone and hydroxyl group, a C to C6 alkylene group, a C ₅ to C ₂ arylene group, a

Oxyalkylene group of the formula -OR ² -, an ester group of the formula

-C (O) -O-R ² - or an amide group of the formula -C (O) -N (R ³ ) R ² -,

E for a hydrocarbon radical having 1 to 10 carbon atoms

R ² is a C ₂ - to C ₀ alkylene radical,

R ^{3 is} hydrogen or a C ¹ to C 10 -alkyl radical which may carry substituents,

R ⁴ for a hydrocarbon radical having 1 to 50 carbon atoms

A is a C ₂ - to C 10 -alkylene radical,

k for a number between 1 and 100,

n for a number from 0 to 4999,

m for a number from 1 to 5000,

99.9 mol%, and

by hydroxyl-carrying polymers A), which are the repetitive

Structural unit of the formula (I) containing, with ether carboxylic acids B1) of the formula (III) or ether carboxylic acid esters B2) of the formula (IV) R ¹ -O [-A-O] _k -E-COOH (III) R ⁱ -O-O [-A-O] _k -E -COOR ⁵ (IV) where R ¹ , A, E and k are as defined above have and R ^{5 is} a C 1 -C ₄ -alkyl radical, are irradiated in the presence of water with microwaves, wherein the reaction mixture is heated by the microwave irradiation to temperatures above 100 ° C.

10. The method of claim 9, wherein the polymer in addition to

Structural units of the formula (I) additionally comprises structural units derived from further ethylenically unsaturated monomers.

11. The method of claim 9 and / or 10, wherein the structural units of the formula (I) derived from vinyl alcohol.

12. The method according to one or more of claims 10 and / or 11, wherein the polymer in addition to the structural units of the formula (I) also comprises vinyl acetate derived structural units.

13. Method according to one or more of claims 9 to 12, wherein R ^{1 is} a hydrocarbon radical having 2 to 20 carbon atoms.

14. Process according to one or more of claims 9 to 13, wherein the ether carboxylic acid B1) or the ether carboxylic acid ester B2) is a mixture of at least one ether carboxylic acid and at least one ether dicarboxylic acid or a mixture of at least one ether carboxylic acid ester and at least one ether dicarboxylic acid ester.

15. The method according to one or more of claims 9 to 14, wherein the reaction mixture used for reaction contains 5 to 98 wt .-% water.

16. The method according to one or more of claims 9 to 14, wherein the reaction mixture used for reaction 5 to 98 wt .-% of a mixture from water and one or more water-miscible organic solvents.

17. The method of claim 16, wherein the proportion of the water-miscible organic solvent in the solvent mixture is between 1 and 75 wt .-%.

18. The method according to one or more of claims 9 to 17, wherein the reaction mixture is heated by means of microwave radiation to temperatures above 100 ° C.

19. The method according to one or more of claims 9 to 18, wherein the comonomer units carrying the ester groups of the polymer A)

Ethercarbonsäuren B1) or Ethercarbonsäureestern B2) are transesterified.

20. The method according to one or more of claims 9 to 19, wherein the microwave irradiation takes place in a flow tube of microwave-transparent, refractory material.

21. The method according to one or more of claims 9 to 20, wherein the longitudinal axis of the reaction tube is in the propagation direction of the microwaves in a single-mode microwave applicator.

22. The method according to one or more of claims 9 to 21, wherein the microwave applicator is formed as a cavity resonator.