EP2658882A1

EP2658882A1 - Continuous method for reacting polymers carrying acid groups, with amines

Info

Publication number: EP2658882A1
Application number: EP11805406.3A
Authority: EP
Inventors: Matthias Krull; Roman MORSCHHÄUSER
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: KR20140000295A; JP2014504653A; DE102010056579A1; BR112013016915A2; EA201300774A1; CN103492429A; US20130296458A1; CN103492429B; WO2012089297A1

Abstract

The invention relates to a method for reacting synthetic poly(carboxylic acids) (A), containing at least 10 repetitive structural units of formula (I), wherein R⁹ represents hydrogen, a C₁ to C₄-alkyl group or a group of formula -CH₂-COOH, R¹⁰ represents hydrogen or a C₁ to C₄-alkyl group, R¹¹ represents hydrogen, a C₁ to C₄ alkyl group or -COOH or with amines (B) of general formula (II) HNR¹R² (II), wherein R¹represents a hydrocarbon group having 3 to 50 C atoms, which can be substituted or can contain heteroatoms, and R² represents hydrogen or a hydrocarbon group having 1 to 50 C atoms, which can be substituted or can contain heteroatoms, or R¹ and R² together form a ring with the nitrogen atom to which they are bound. According to the invention, a reaction mixture containing at least one synthetic poly(carboxylic acid) (A) and at least one amine of formula (II) in a solvent mixture which contains water, and with respect to the weight of the solvent mixture, 0.1 - 75 wt.-% of at least one organic solvent which can be mixed with water.,said organic solvent having a dielectric constant of at least 10 when measured at 25 °C, is introduced into a reaction path and is exposed to microwave radiation when it flows through the reaction path. Said reaction mixture is heated to temperatures over 100 °C by the microwave radiation in the reaction path.

Description

description

Continuous process for reacting acid group-bearing polymers with amines

The present invention relates to a continuous process for reacting acid group-bearing polymers by polymer-analogous amidation of

Solutions of polymers in the microwave field. Hydrophobically modified water-soluble synthetic polymers have gained increasing industrial importance in recent years. These are usually polymers which are composed mainly of monomers carrying hydrophilic groups and a smaller proportion of monomers carrying hydrophobic groups. These water-soluble polymers aggregate in aqueous solutions due to intra- and / or intermolecular interactions of the hydrophobic groups with micelle-like structures. As a result, the hydrophobically modified polymers cause an increase in viscosity compared with conventional water-soluble polymers by the formation of three-dimensional networks at low concentrations, without requiring extremely high molecular weights. Such "associative thickeners" efficiently control the rheological properties of aqueous based fluids in many industrial applications or formulations, such as in paints and coatings, paper, drilling fluids, and oil recovery

In pharmaceutical and cosmetic applications, these polymers are used, for example, as stabilizers for colloidal dispersions, emulsions, liposomes or (nano) particles. Further, they are used as dispersing agents for pigments and dyes wherein the modified polymer acts as a hydrophobic particle dispersant by anchoring the hydrophobic polymer segments to the solid surface and by extending the charged, hydrophilic groups into the bulk phase.

A special case of the hydrophobically modified water-soluble polymers are so-called LCST polymers (Lower Critical Solution Temperature), whose Lose side chains with increasing temperature of water solubility and thus lead to an aggregation or precipitation of the polymer with temperature increase. Such polymers are, for example, in the petroleum production as

Drilling mud additives of great interest.

The rheological properties of hydrophobically modified, water-soluble, synthetic polymers can be adjusted within wide limits, for example, by selecting the hydrophobic group and / or the degree of modification and thus adapting it to a wide variety of applications.

An important group of hydrophobically associating, water-soluble macromolecules are hydrophobically modified synthetic poly (carboxylic acids) and

Poly (carboxamides). These can be, for example, by

Copolymerization of ethylenically unsaturated carboxylic acids and / or

Carboxylic acid amides bearing appropriate hydrophobic groups

Produce monomers. In this case, as hydrophobic comonomers in particular substituted on the nitrogen ethylenically unsaturated

Carboxylic acid amides proven because they have the hydrophilic monomers comparable Copolymerisationsparameter but have a relation to corresponding esters increased hydrolysis stability. However, its technical

Availability is limited both in the variation of the substituents and in terms of quantity and their synthesis is complicated and expensive. It usually takes place via the reaction of reactive carboxylic acid derivatives such as

Anhydrides or acid chlorides with amines, with equimolar amounts to be separated and disposed of by-products. Furthermore, the preparation of random copolymers is often due to different solubilities of hydrophilic and hydrophobic monomers

Difficulties. Alternatively, such polymers are also accessible by polymer-analogous reactions of synthetic higher molecular weight poly (carboxylic acids), which are technically available in large quantities. According to the prior art, such polymer-analogous reactions between poly (carboxylic acids) and amines with Coupling reagents such as A /./ V-dicyclohexylcarbodiimide (DCC) can be performed. The problem is again process-related by-products and the different solubilities of the reactants, which often leads to inhomogeneous products. If the poly (carboxylic acids) are sufficiently oil-soluble, condensation in organic solvents with azeotropic removal of the water of reaction is also possible.

A recent approach to the synthesis of carboxylic acid amides is by

Microwave assisted direct conversion of carboxylic acids and amines to amides. In contrast to classical processes, no activation of the carboxylic acid over, for example, acid chlorides, acid anhydrides, esters or coupling reagents is required, which makes these processes very interesting both economically and ecologically.

Tetrahedron Letters 2005, 46, 3751-3754 discloses a variety of amides synthesized with the aid of microwave radiation.

Macromolecular Chemistry and Physics (2008), 209, 1942-1947 discloses the polymer-analogous amidation of an acid group-bearing poly (ether sulfone) with 4-aminobenzoic acid in apolar solvents under microwave irradiation.

J. Polym. Sei., Part A: Polym. Chem. (2007), 45, 3659-3667 discloses the polymer-analogous amidation of poly (ethylene-co-acrylic acid) with excess 2- (2-aminoethoxy) ethanol in toluene under microwave irradiation to yield amidated, hydroxy-functionalized polymers. After a

Irradiation time of 90 minutes at 240 ° C, a conversion of 87% of

Achieved acid groups. WO 2009/121488 discloses the condensation of carboxylic acids with amines to amides in the microwave field in the presence of superheated water.

However, the teaching of WO 2009/121488 is limited to the implementation monomeric carboxylic acids. On higher molecular weight synthetic poly (carboxylic acids), this process can not be transferred directly. For implementations in the

technical scale required more highly concentrated aqueous solutions of higher molecular weight synthetic poly (carboxylic acids) have a very high viscosity, which impedes both the production of homogeneous reaction mixtures with amines and their handling, for example, during stirring or pumping. In particular, for a partial amidation of the carboxyl groups prepares the preparation of aqueous solutions of ammonium salts with random distribution of the ammonium groups over the entire chain length of the polymer due to viscosity and solubility differences between poly (carboxylic acid) and amine usually considerable difficulties. Thus, in the implementation of high molecular weight synthetic poly (carboxylic acids) with hydrophobic amines with correspondingly low water solubility even under very strong and intense stirring or mixing with special stirring or mixing units often can not achieve satisfactory results. Furthermore, it already requires the

unreacted reaction mixture not negligible and with the onset of formation of hydrophobically modified structural units further strongly increasing viscosity of aqueous solutions of synthetic poly (carboxylic acids) special delivery units for maintaining a necessary in continuous processes flow of the reaction mixture through the irradiation zone. Often, even strong pumps are not enough and it has to be with delivery units like

for example, snails or Archimedean screws are worked. In addition to mechanical strength, such aggregates require special requirements for the material in the case of microwave-assisted reactions

For example, provided microwave transparency, the assurance requires a lot of effort. Furthermore, such mechanical devices limit the geometry of the irradiation zone.

It was therefore the object of a continuous process for

polymer-analogous modification of synthetic poly (carboxylic acids)

in which the properties of synthetic poly (carboxylic acids) can be modified in a simple and inexpensive manner in industrially interesting quantities. In particular, in the reaction mixture should not high Viscosities occur that require the use of special delivery units. The solubility and the aggregation behavior of the polymers produced should be influenced within wide limits. To achieve a constant

Product properties both within a reaction mixture as well as between different reaction mixtures, the modification should be as homogeneous as possible, that is to say in statistical distribution over the entire polymer. Furthermore, no appreciable amounts of toxicologically and / or ecologically harmful by-products should arise. Surprisingly, it was found that synthetic

Poly (carboxylic acids) in solutions in water and certain water-miscible solvents with amines under the influence of microwaves at temperatures above 100 ° C in a continuous process amidated. In the course of the process, the viscosity increases only slightly, if at all. In this way, poly (carboxylic acids) can be modified, for example, hydrophobic as well as thermoassociating. The solubility of such modified polymers gives no indication of the presence of larger hydrophilic or hydrophobic polymer blocks. Since a variety of different amines is inexpensive and accessible in technical quantities, thus the properties of synthetic poly (carboxylic acids) can be modified within wide limits. In addition to reaction water, this process eliminates by-products to be separated and disposed of.

The invention accordingly provides a continuous process for the reaction of synthetic poly (carboxylic acids) (A) containing at least 10 repeatable structural units of the formula (I)

wherein

R ^{9 is} hydrogen, a C 4 to C 4 alkyl group or a group of

formula

-CH2-COOH

R ^{10 is} hydrogen or a C 1 to C ₄ alkyl group

R ^{11 is} hydrogen, a C 1 to C 4 alkyl group or -COOH

mean, with amines (B) of the general formula (II) HNR ¹ R ² (II) wherein

R ^{1 is} a hydrocarbon radical having 3 to 50 carbon atoms, which may be substituted or may contain heteroatoms, and R ^{2 is} hydrogen or a hydrocarbon radical having 1 to

50 C atoms, which may be substituted or may contain heteroatoms, stand or

R ¹ and R ² together with the nitrogen atom to which they are attached, a

Form ring,

in which a reaction mixture containing at least one synthetic

Poly (carboxylic acid) (A) and at least one amine of the formula (II) in one

Solvent mixture, which water and, based on the weight of

Solvent mixture containing 0.1 to 75 wt .-% of at least one water-miscible organic solvent, and wherein the organic solvent has a measured at 25 ° C dielectric constant of at least 10, is placed in a reaction zone, and exposed to microwave radiation as it flows through the reaction section is, and wherein the reaction mixture in the reaction section by the microwave irradiation to temperatures above 100 ° C is heated.

Another object of the invention are prepared by the process according to the invention, polymer-analogue modified synthetic

Poly (carboxylic acids). Preferably, R ^{9 is} hydrogen or a methyl group. Furthermore, R ⁰ is preferably hydrogen. Further preferably, R ^{1 is} hydrogen or -COOH. In a specific embodiment, R ⁹ , R ¹⁰ and R ¹¹ stand for

Hydrogen. In another specific embodiment, R ^{9 is} a methyl group and R ¹⁰ and R ^{1 are} hydrogen. In another special

Embodiment R ⁹ and R ^{10 are} hydrogen and R ^{1 is} -COOH.

Synthetic poly (carboxylic acids) (A) are polymers which can be prepared by addition polymerization of ethylenically unsaturated carboxylic acids. Preferred synthetic poly (carboxylic acids) contain structural units derived from acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid or mixtures thereof. The concept of derived

Structural units means that the polymer contains structural units which are formed in the addition polymerization of said acids. Particularly preferred are homopolymers of said ethylenically unsaturated carboxylic acids such as poly (acrylic acid), and poly (methacrylic acid). Also preferred are copolymers of two or more, for example three or more, ethylenically unsaturated carboxylic acids and in particular the abovementioned ethylenically unsaturated carboxylic acids, for example from acrylic acid and maleic acid or from acrylic acid and itaconic acid.

The inventive method is also for the modification of

Poly (carboxylic acids) suitable, in addition to the derived from the above ethylenically unsaturated carboxylic acid structural units minor amounts of up to 50 mol% of further ethylenically unsaturated

Containing monomer-derived structural units. The proportion of structural units derived from further ethylenically unsaturated monomers is preferably between 0.1 and 40 mol%, particularly preferably between 0.5 and 25 mol% and in particular between 1 and 10 mol%, for example between 2 and 5 mol%. %. Preferred further ethylenically unsaturated monomers are

for example, other monomers carrying acid groups and in particular monoethylenically unsaturated compounds having carboxyl groups such as for example, vinylacetic acid or allylacetic acid, with sulfate or

Sulfonic acid groups such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate,

2-acrylamido-2-methylpropanesulfonic acid (AMPS) or

2-Methacrylamido-2-methylpropanesulfonic acid and monoethylenically

unsaturated compounds having phosphate or phosphonic acid groups such as vinylphosphoric acid, vinylphosphonic acid, allylphosphonic acid, methacrylamidomethanephosphonic acid,

2-Arylamido-2-methylpropane phosphonic acid, 3-phosphonopropyl acrylate or 3-phosphonopropyl methacrylate. Also vinyl esters of CC ₂ o-carboxylic acids and especially C ₂ -C5 carboxylic acids such as vinyl acetate and vinyl propionate, esters of acrylic and methacrylic acid with Ci-C ₂ o-alcohols and especially

C ₂ -C 6 -alcohols such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate and acrylamide and methacrylamide and their nitrogen

Ci-C ₂ o-alkyl radicals substituted derivatives, vinyl ethers such as

Methyl vinyl ethers, N-vinyl compounds such as N-vinyl caprolactam and N-vinyl pyrrolidone and olefins such as ethylene, styrene and butadiene are useful as other comonomers. Preferred copolymers are in

Solvent mixture of water and the water-miscible organic solvent at temperatures above 40 ° C such as at 50 ° C, 60 ° C, 70 ° C, 80 ° C or 90 ° C homogeneously soluble or at least swellable. Furthermore, they are preferably present at a concentration of at least 1% by weight and in particular from 5 to 90% by weight, for example from 20 to 80% by weight

Temperatures above 40 ° C such as 50 ° C, 60 ° C, 70 ° C, 80 ° C or 90 ° C homogeneously soluble or swellable in the solvent mixture. Examples of preferred copolymers are copolymers of

- acrylic acid or methacrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS ^®) -Na-salt,

Acrylic acid and 2-ethylhexyl acrylate,

- acrylic acid and acrylamide,

Acrylic acid and dimethylacrylamide, Methacrylic acid or acrylic acid with tert-butyl methacrylate,

- maleic acid and styrene, as well

- maleic acid and vinyl acetate. In copolymers of various ethylenically unsaturated carboxylic acids as well as in copolymers of ethylenically unsaturated carboxylic acids with other comonomers, the structural units of the formula (I) derived from ethylenically unsaturated carboxylic acids may be distributed in blocks, alternately or randomly.

The synthetic poly (carboxylic acids) (A) contain at least 10 repeating structural units of the formula (I), which is to be understood per polymer chain.

Poly (carboxylic acids) (A) which are preferred according to the invention have number-average molecular weights above 700 g / mol, more preferably between 1,000 and 500,000 g / mol and in particular between 2,000 and 300,000 g / mol, for example between 2,500 and 100,000 g / mol, in each case determined by gel permeation chromatography against poly (styrenesulfonic acid) standards.

Further preferably, the poly (carboxylic acids) contain (A) on average at least 10 and in particular at least 20 such as 50 bis

8,000 carboxyl groups per polymer chain. They preferably contain at least 20, in particular at least 50, structural units of the formula (I) per polymer chain. The process according to the invention is preferably suitable for the preparation of secondary amides, ie for the reaction of poly (carboxylic acids) (A) with amines of the formula (II) in which R ^{1 is} a hydrocarbon radical having 3 to 50 carbon atoms and R ^{2 is} hydrogen. The inventive method is further preferably for the production of tertiary amides, that is, for the reaction of poly (carboxylic acids) (A) with amines of the formula (II), wherein R ^{1 is} a hydrocarbon radical having 3 to

50 carbon atoms and R ² for a hydrocarbon radical with 1 to 100 carbon atoms. The radicals R ¹ and R ² may be the same or different. In a particularly preferred embodiment, R ¹ and R ^{2 are the} same. In a specific embodiment, R ¹ and R ² together with the nitrogen atom to which they are attached form a ring.

In a first preferred embodiment, R ^{1 is} an aliphatic radical. This has preferably 4 to 24, particularly preferably 5 to 18 and especially 6 to 12 C-atoms. The aliphatic radical may be linear, branched or cyclic. It can still be saturated or unsaturated. Preferably, the aliphatic radical is saturated. The aliphatic radical may carry substituents such as, for example, hydroxyl, C 1 -C ₅ -alkoxy, cyano, nitrile, nitro and / or C ₅ -C ₂ 0-aryl groups, for example phenyl radicals. The Cs-C20-aryl radicals may in turn optionally be substituted by halogen atoms, halogenated alkyl radicals, C 1 -C 20 -alkyl, C 2 -C 20 -alkenyl, hydroxyl, C 1 -C 8 -alkoxy, for example methoxy, amide, cyano, , Nitrile, and / or nitro groups. In a particularly preferred embodiment, R ^{1 is} a C 3 -C 6 -alkyl or -cycloalkyl radical. These radicals can carry up to three substituents. Particularly preferred aliphatic radicals R ¹ are n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, n-pentyl, isoamyl, n-hexyl, cyclohexyl, n-octyl, n-decyl, n- Dodecyl, tridecyl, isotridecyl, tetradecyl, hexadecyl, octadecyl and methylphenyl.

R ² is preferably hydrogen. In a further preferred

Embodiment R ^{2 is} an aliphatic radical. This has preferably 1 to 24, more preferably 2 to 18 and especially 3 to 6 C-atoms. The aliphatic radical may be linear, branched or cyclic. It can still be saturated or unsaturated. Preferably, the aliphatic radical is saturated. The aliphatic group may have substituents such as hydroxyl, Ci-C wear ₅ alkoxy, cyano, nitrile, nitro and / or _C5-C2o-aryl groups such as phenyl. The C ₅ -C ₂₀ -aryl radicals may in turn optionally substituted with halogen atoms, halogenated alkyl groups, _{Ci-C2o-alkyl,} C ₂ -C ₂ o-alkenyl, hydroxyl, CC ₅ alkoxy such as methoxy, amide -, cyano, nitrile, and / or nitro groups substituted. In a particularly preferred embodiment, R ^{2 is} hydrogen, a C ¹ -C 6 -alkyl or C ³ -C 6 -cycloalkyl radical and especially one Alkyl radical having 1, 2, or 3 C atoms. These radicals can carry up to three substituents. Particularly preferred aliphatic radicals R ² are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, n-hexyl, cyclohexyl, n-octyl, n-decyl, n-dodecyl, Tridecyl, isotridecyl, tetradecyl, hexadecyl, octadecyl and

Methylphenyl.

In another preferred embodiment, R ¹ and R ² together with the nitrogen atom to which they are attached form a ring. This ring preferably has 4 or more, such as 4, 5, 6 or more ring members.

Preferred further ring members are carbon, nitrogen, oxygen and / or sulfur atoms. The rings in turn may carry substituents such as alkyl radicals. Suitable ring structures are

for example, morpholinyl, pyrrolidinyl, piperidinyl, imidazolyl and

Azepanyl radicals.

In a further preferred embodiment, R ¹ and / or R ²

independently represent an optionally substituted C ₆ -C ₂ aryl group or an optionally substituted heteroaromatic group having 5 to 12 ring members.

In a further preferred embodiment, R ¹ and / or R ²

independently of one another for a heteroatom-interrupted alkyl radical. Particularly preferred heteroatoms are oxygen and nitrogen. Thus, R ¹ and / or R ² independently of one another are preferably radicals of the formula (III)

- (R ³ -O) _n -R ⁴ (III) wherein

R ^{3 is} an alkylene group having 2 to 6 carbon atoms and preferably 2 to

4 C atoms such as ethylene, propylene, butylene or

Mixtures thereof, for hydrogen, a hydrocarbon radical having 1 to 24 carbon atoms, an acyl radical of the formula -C (= O) -R ¹² , wherein R ^{12 is} a

Hydrocarbon radical having 1 to 50 carbon atoms, or a group of the formula -R ³ -NR ⁵ R ⁶ ,

for a number between 2 and 100, preferably between 3 and 50 and in particular between 4 and 25 such as between 5 and 10 and

independently of one another are hydrogen, an aliphatic radical having 1 to 24 C atoms and preferably 2 to 18 C atoms, an aryl group or heteroaryl group having 5 to 12 ring members, one

Poly (oxyalkylene) group having 1 to 50 poly (oxyalkylene) units, wherein the polyoxyalkylene units derived from Alyklenoxideinheiten having 2 to 6 carbon atoms, or R ⁵ and R ⁶ together with the nitrogen atom to which they are attached, a ring with 4, 5, 6 or more ring members form, stand.

According to the invention, particularly suitable polyetheramines (B) in which at least one of the radicals R ¹ and / or R ² corresponds to the formula (III) are, for example, by alkoxylating alcohols of the formula R ⁴ -OH with 2 to 100 mol

Ethylene oxide, propylene oxide or a mixture thereof and subsequent

Transfer of the terminal hydroxyl group into an amino group accessible. Preferred polyetheramines have molecular weights between 500 and

7,000 g / mol and more preferably between 600 and 5,000 g / mol such as between 800 and 2,500 g / mol.

Furthermore, R ¹ and / or R ² independently of one another are preferably radicals of the formula (IV)

- [R ⁷ -N (R ⁸ )] _m - (R ⁸ ) (IV)

represents an alkylene group having 2 to 6 C atoms and preferably having 2 to 4 C atoms, such as, for example, ethylene, propylene or mixtures thereof, each R .8 is independently hydrogen, an alkyl or

Hydroxyalkyl radical having up to 24 carbon atoms such as 2 to 20 carbon atoms, a polyoxyalkylene radical - (R ³ -0) _p -R ⁴ , or a polyiminoalkylene radical - [R ⁷ -N (R ⁸ )] _q - (R ⁸ ), wherein R ³ , R ⁴ , R ⁷ and

R have the meanings given above and q and p independently of one another are from 1 to 50 and

m is a number from 1 to 20, and preferably from 2 to 10, such as three, four, five or six. The radicals of the formula (I) preferably contain 1 to 50, in particular 2 to 20, nitrogen atoms.

Depending on the stoichiometric ratio between poly (carboxylic acid) (A) and

Polyamine of formula (IV) are one or more amino groups, each carrying at least one hydrogen atom, converted into the carboxylic acid amide. In the reaction of poly (carboxylic acids) (A) with polyamines of the formula III, primary amino groups can also be converted into imides.

Examples of suitable amines are n-propylamine, iso-propylamine, propanolamine, butylamine, hexylamine, cyclohexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, dimethylamine, diethylamine, diethanolamine, ethylmethylamine, di-n-propylamine, di-iso propylamine, methyl-n-propylamine, methyl-iso-propylamine, dicyclohexylamine, didecylamine,

Didodecylamine, ditetradecylamine, dihexadecylamine, dioctadedcylamine,

Benzylamine, phenylethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, Ν, Ν-dimethylethylenediamine, N, N-diethylaminopropylamine, Ν, Ν-dimethylaminopropylamine, N, N- (2'-hydroxyethyl) -1, 3-propanediamine,

Polyetheramines with 2 to 50 moles of alkylene oxide such as ethylene and / or propylene oxide and 1- (3-aminopropyl) pyrrolidine and mixtures thereof. Particularly preferred are dimethylamine, diethylamine, diethanolamine, methyl-n-propylamine, methyl-iso-propylamine, di-n-propylamine, di-iso-propylamine, ethylmethylamine, methoxyethoxypropylamine and N, N-dimethylaminopropylamine.

In the process according to the invention, poly (carboxylic acid) (A) and amine (B) can generally be reacted with one another in any desired ratios. The reaction with molar ratios between carboxyl groups of the poly (carboxylic acid) (A) and amino groups of the amine (B) preferably takes place from 100: 1 to 1: 5, preferably from 10: 1 to 1: 1, especially from 5: 1 to 2 : 1, in each case based on the equivalents of carboxyl and amino groups. If the amine is in

Excess is used or is not completely reacted, portions thereof remain unreacted in the polymer, which can remain depending on the purpose in the product or can be separated. This method is particularly advantageous when the amine used is readily volatile or water-soluble. Volatile here means that the amine has a boiling point at atmospheric pressure of preferably below 250 ° C such as below 150 ° C and thus, optionally together with solvent, can be separated from the amide. This can be done for example by means of distillation, phase separation or extraction. By the ratio of amine to carboxyl groups of the polymer, the degree of modification and thus the properties of the product can be adjusted.

Particularly preferred is the inventive method for the partial

Amidation of poly (carboxylic acids) (A) suitable. The amine (B) is substoichiometric based on the total number of carboxyl groups

used, in particular in the ratio 1: 100 to 1: 2 and especially in the ratio 1: 50 to 1: 5 such as in the ratio 1: 20 to 1: 8. The reaction conditions are preferably adjusted so that at least 10 mol%, in particular 20 to 100 mol% and especially 25 to 80 mol%, for example 30 to 70 mol% of the amine (B) used are reacted. In these partial amidations very homogeneous products are formed, which shows in a good solubility and a sharp cloud point of aqueous solutions.

In the event that R ¹ and / or R ^{2 is} one with one or more

Hydroxyl-substituted hydrocarbon radical, the

Reaction between poly (carboxylic acid) (A) and amine (B) preferably with molar ratios of 1: 1 to 1: 5 and especially from 1: 1, 01 to 1: 3 such as from 1: 1, 1 to 1: 2 , in each case based on the molar equivalents of carboxyl groups and Amino groups in the reaction mixture.

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

Reaction mixture containing poly (carboxylic acid) (A), amine (B), water, a water-miscible solvent and optionally other auxiliaries such as emulsifier, catalyst and / or electrolyte can be carried out in various ways. The resulting ammonium salt is preferably generated in situ and not isolated. The mixing of poly (carboxylic acid) (A) and amine (B) can be carried out continuously, batchwise or else 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 poly (carboxylic acid) (A) is preferably fed to the inventive method as a solution in water or as a solution in water and a water-miscible solvent. The poly (carboxylic acid) (A) can also be used in swollen form, provided that it is pumpable.

The amine (B), insofar as it is liquid or meltable at low temperatures of preferably below 150 ° C. and in particular below 100 ° C., can be used as such. In many cases, it has proven useful to use the amine (B) optionally in a molten state, mixed with water and / or the water-miscible solvent, for example as a solution, dispersion or emulsion.

The mixing of poly (carboxylic acid) (A) with amine (B) can be carried out in a (semi) -batch process by sequential charging of the ingredients, for example in a separate stirred tank. In a preferred

Embodiment, the amine (B) is dissolved in the 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 amine and on the other hand to avoid local precipitation of the polymer at the metering. Particularly preferably, the mixing of poly (carboxylic acid) (A) with amine (B) or their solutions or dispersions as described above and optionally further excipients in a mixing section, from which the

Reaction mixture, optionally after intermediate cooling, in the

Reaction path is promoted.

If used, a catalyst and further auxiliaries can be added to one of the educts or else to the educt mixture before it enters the reaction zone. Also heterogeneous systems can after the

inventive methods are implemented, with only appropriate technical devices for conveying the reaction mixture are required.

Preferably, the reaction mixture contains 10 to 99 wt .-%, particularly preferably 20 to 95 wt .-%, in particular 25 to 90 wt .-% such as 50 to 80 wt .-% of a solvent mixture of water and one or more miscible with water , organic solvents. In any case, water is added to reactants A and B prior to microwave irradiation so that the reaction product contains an amount of water in excess of the amount of water of reaction liberated during the amidation.

Preferred water-miscible organic solvents are polar protic and polar aprotic liquids. These preferably have a dielectric constant of at least 12, and in particular at least 15, measured at 25 ° C. Preferred solvents are soluble in water to at least 100 g / l, more preferably to at least 200 g / l, in particular to at least 500 g / l, and especially they are completely miscible with water. 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.

Preferred aprotic solvents are, for example, formamide,

N, N-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 carbon atoms and in particular with 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-butanol, isoamyl alcohol, 2-methyl-2 butanol, ethylene glycol and glycerin. Secondary and tertiary alcohols are particularly preferably used as lower alcohols. Particularly preferred are secondary and tertiary alcohols having 3 to 5 carbon 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. The proportion of the water-miscible organic solvent in the solvent mixture is preferably between 1 and 60% by weight, more preferably between 2 and 50% by weight, in particular between 5 and 40% by weight, for example between 10 and 30% by weight. %, in each case based on the weight of the solvent mixture. Water is contained in the solvent mixture ad 100 wt .-%.

To further reduce the viscosity of the reaction mixture used and / or the solution of the polymer polymer modified polymer formed in the course of the process according to the invention, it has proven itself many times

Reaction mixture to add electrolytes. Preferred are strong electrolytes which are completely dissociated, regardless of the concentration. Preferred strong electrolytes are salts of alkali and alkaline earth metals such as, for example, their chlorides, phosphates, sulfates, carbonates and bicarbonates. Examples of preferred strong electrolytes are NaCl, KCl, Na ₂ C0 ₃ , Na ₂ S0 ₄ and MgS0 ₄ . At the same time, the addition of electrolytes increases the dielectric loss of the reaction medium, so that more energy is consumed per unit of time or volume the reaction mixture can be coupled. For the continuous process according to the invention, this means an increase in the amount that can be converted per unit time, since more of the reaction mixture in the reaction zone can be heated to the desired temperature while increasing the flow rate (and simultaneously the irradiated microwave energy).

When using amines (B) having limited solubility in water or the mixture of water and water-miscible organic solvents, one or more emulsifiers may be added to the reaction mixture in a preferred embodiment. Preference is given to using emulators which are chemically inert to the educts and to the product. In a particularly preferred embodiment, the emulsifier is a reaction product from a separate preparation. In a preferred embodiment, the reactants are fed in the desired ratio of separate templates of the reaction route. In a special embodiment they will be before entering the

Reaction zone and / or further homogenized in the reaction section itself by means of suitable mixing elements such as static mixer and / or Archimedean screw and / or by flowing through a porous foam.

The reaction of poly (carboxylic acid) (A) with amine (B) takes place according to the invention under the influence of microwave radiation in a reaction zone. The reaction zone comprises at least one vessel in which the reaction mixture is exposed to microwave radiation (irradiation zone) and optionally an isothermal reaction zone adjoining it in the flow direction, in which the reaction can be completed. In the simplest case, the reaction zone consists of the irradiation zone. In the irradiation zone, the reaction mixture by microwave radiation is preferably at temperatures above 110 ° C, more preferably at temperatures between 120 and 320 ° C, in particular between 130 and 260 ° C and in particular between 140 and 240 ° C such as between 150 and 220 ° C. heated. 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. It is preferably determined on the reaction mixture directly after leaving the irradiation zone. The pressure in the reaction zone is preferably set so high that the reaction mixture remains in the liquid state and does not boil. Is preferred 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 as

for example, worked between 15 and 50 bar.

To speed up or complete the reaction, it has proven useful in many cases to work in the presence of dehydrating catalysts. Dehydrating catalysts are understood as meaning auxiliaries which accelerate the condensation of amine and carboxylic acid. Preferably, one works in the presence of an acidic inorganic, organometallic or organic catalyst or mixtures of several of these catalysts. Preferred catalysts are liquid and / or soluble in the reaction medium.

Preference is furthermore given to using from 0.01 to 10% by weight, preferably from 0.02 to 2% by weight, of catalyst. In a particularly preferred embodiment, working without a catalyst.

After microwave irradiation, the reaction mixture can in many cases be fed directly to another use. To obtain solvent-free products, water and / or organic solvent can be separated from the crude product by conventional separation techniques such as distillation, freeze-drying or absorption. In this case, amine used in excess and optionally unreacted residual amounts of amine can also be separated off. For special requirements, the crude products can be further purified by conventional purification methods such as, for example, washing, reprecipitation, filtration, dialysis or chromatographic methods. Often, it has also proved to be successful here to neutralize excess or unreacted amine and remove by washing. The microwave irradiation is usually carried out in apparatuses which have an irradiation vessel made of a material which is as far as possible transparent to microwaves, in the microwave generated in a microwave generator

Microwave radiation is coupled. Microwave generators, like

for example, the magnetron, the klystron and the gyrotron are the

Specialist known.

The used for carrying out the method according to the invention

Irradiation vessels are preferably made of largely microwave-transparent, high-melting material or contain at least parts such as windows made of these materials. Non-metallic irradiation 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 ^' Υε ^' 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 irradiation 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 preferred

Microwave-transparent and temperature-stable materials are primarily materials based on minerals such as quartz, aluminum oxide, zirconium oxide, silicon nitride and the like into consideration. Also, temperature-stable plastics such as in particular fluoropolymers such as Teflon, and engineering plastics such as polypropylene, or polyaryletherketones such

For example, glass fiber reinforced polyetheretherketone (PEEK) are as

Vascular materials suitable. In order to withstand the temperature conditions during the reaction, minerals coated with these plastics in particular, such as quartz or aluminum oxide, have proven to be useful as vessel materials. As microwaves are electromagnetic radiation having a wavelength between about 1 cm and 1m 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

Irradiation vessel to be irradiated microwave power is particularly dependent on the desired reaction temperature, the geometry of the

Irradiation vessel and the associated reaction volume and the flow rate of the reaction mixture through the irradiation 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 irradiation 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 irradiation 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 especially between one second and 5 minutes such as between 5 seconds and 2 minutes

performed. The intensity (power) of the microwave radiation is adjusted so that the reaction mixture in the shortest possible time the desired Reaction temperature reached. In a further preferred embodiment of the method according to the invention, it has proven useful to supply the reaction mixture to the irradiation vessel in heated form. To maintain the reaction temperature, the reaction product may be further irradiated with reduced and / or pulsed power 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 is preferably carried out in a flow tube serving as an irradiation vessel, which is also referred to below as the reaction tube. It can also be carried out in semi-batch processes such as continuously operated stirred reactors or cascade reactors. In a preferred embodiment, the reaction is carried out in a closed, pressure-resistant and chemically inert vessel, wherein the water and optionally the amine and the water-miscible solvent lead to a pressure build-up. After completion of the reaction, the pressure can be reduced by venting to volatilize and separate water, organic

Solvent and optionally excess amine and / or used to cool the reaction product. In a particularly preferred embodiment, the reaction mixture is terminated after completion of the

Microwave irradiation or freed as soon as possible after leaving the irradiation vessel of water and optionally present catalytically active species to prevent hydrolysis of the resulting amide. The water and the organic solvent can be separated by conventional separation methods such as freeze-drying, distillation or absorption. Often, it has also proved to be successful in this, to neutralize excess amine and remove by washing.

In a particularly preferred embodiment of the process according to the invention, the reaction mixture is continuously passed through a pressure-resistant, inert to the reactants, for the most part transparent to microwaves and fed into a microwave applicator serving as the irradiation zone reaction tube. 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.

Under flow or reaction tubes are understood here 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 surrounded on its length by at least one, but preferably by several such as, for example, two, three, four, five, six, seven, eight or more microwave radiators. 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 section is usually provided at the inlet with a metering pump and a pressure gauge and at the outlet with a pressure-holding device and a heat exchanger. Preferably, the reaction mixture of

Reaction path in liquid form with temperatures below 100 ° C like for example, supplied between 10 ° C and 90 ° C. In a further preferred embodiment, a solution of the polymer (A) and amine (B) only shortly before entering the reaction zone, optionally with the aid of suitable mixing elements such as static mixer and / or Archimedean screw and / or by flowing through a porous foam mixed. In a further preferred embodiment, they are further homogenized in the reaction zone by means of suitable mixing elements such as static mixers and / or Archimedean screw and / or 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, such as 3 to 0 times the wavelength of the used Microwave radiation. With this geometry, energy from several, such as two, three, four, five, six or more consecutive maxima of the propagating parallel to the longitudinal axis of the tube microwave can be 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 referred to in English as TMoi _n mode (transverse magnetic), see, for example, K. Lange, KH 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, the reaction tube is aligned axially with a central axis of symmetry of the cavity resonator, for which purpose the cavity resonator preferably each has 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 to the resonator via a waveguide, wherein the from the cavity resonator outstanding 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 special embodiment, the irradiation of the

Reaction mixture with microwaves in a microwave transparent

Reaction tube, which is axially symmetrical in a Eoi _n -Rundhohlleiter 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 reaction mixture with microwaves in a microwave-transparent reaction tube, which is passed through a Eoi _n- cavity resonator with axial feeding 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 passed through an Eoi _n- cavity resonator with axial feeding of the microwaves, wherein the length of the

Cavity resonator is dimensioned so that forms a standing wave with n = 2 or more 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 axially symmetric in a circular cylindrical E ₀ i _n cavity resonator with coaxial transition of the microwaves, wherein the length of the cavity resonator is dimensioned so that n = 2 or more microwave field maxima. In a further preferred embodiment, the irradiation of the reaction mixture with microwaves in a microwave-transparent reaction tube, which is axially symmetrical in a circular cylindrical E ₀ i _n cavity resonator with coaxial transition of the microwaves is carried out, the length of the

Cavity resonator 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

Eoi cavity resonators preferably have a diameter which 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 Eor cavity resonator has a round cross section, which is also referred to as Eoi round waveguide. Particularly preferably it has a cylindrical shape and especially a circular cylindrical shape.

The reaction of the reaction mixture is on leaving the

Irradiation zone often not yet in chemical equilibrium. In a preferred embodiment, the reaction mixture is therefore transferred directly after passage of the irradiation zone, that is without intermediate cooling in an isothermal reaction zone, in which it continues for a certain time

Reaction temperature is maintained. Only after leaving the isothermal

Reaction section, 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. The temperature difference between leaving the irradiation zone and entering the isothermal reaction zone is preferably less than ± 30 ° C., preferably less than ± 20 ° C., more preferably less than ± 10 ° C. and in particular 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 stay in this

Reaction temperature for a defined period of time before it is cooled. In this embodiment, the reaction mixture is preferably cooled as quickly as possible directly after leaving the isothermal reaction zone 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, which lingering of the reaction mixtures at 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 maximum temperature of ± 30 ° C, preferably ± 20 ° C, more preferably ± 10 ° C and especially ± 5 ° C of the

Temperature differs when entering the isothermal reaction zone.

In addition to continuously operated stirred tanks and tank cascades pipes are particularly suitable as an isothermal reaction path. 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. Over the length of the tube and / or its cross-section can be determined at a given flow rate, the residence time of the reaction mixture. That as an isothermal reaction path functioning tube is thermally insulated in the simplest case, so that the temperature prevailing upon entry of the reaction mixture into the isothermal reaction zone 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 jacketed 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 inventive method allows the polymer-analogous modification of synthetic poly (carboxylic acids) with amines in a continuous process in industrially interesting amounts. In addition to water, none of them arise Disposal and environmental polluting by-products. Another advantage of the method lies in the fact that the

polymer-analogous condensation reactions can be carried out in aqueous solution, since water is one of the few solvents suitable for poly (carboxylic acids). The addition of certain polar organic solvents may counteract any increase in viscosity occurring during the course of the process and facilitate the reaction with less water-soluble amines. In this way, poly (carboxylic acids) can be modified, for example, hydrophobic as well as thermoassociating. 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 of amines opens a large

Range of modification options. Thus, the properties of synthetic poly (carboxylic acids) can be modified in a wide range in a simple manner.

Examples The irradiation of the reaction mixtures with microwaves was carried out in one

Aluminum oxide reaction tube (60 x 1 cm) axially symmetric in a cylindrical cavity resonator (60 x 10 cm). At one of the end faces of the cavity resonator, the reaction tube passed through the cavity of an inner conductor tube functioning as a coupling antenna. 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 there is 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. From the difference between incident energy and heating of this water load, the microwave energy introduced into the reaction mixture was calculated

By means of a high pressure pump and a pressure relief valve, the reaction mixture was placed in the reaction tube under such a working pressure, which was sufficient to keep all starting materials and products or condensation products always in the liquid state. The reaction mixtures were pumped through the device at a constant flow rate and the residence time in the

Irradiation zone 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: Amidation of poly (methacrylic acid) with octylamine

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

Internal thermometer and pressure equalization became a solution of 1, 4 kg

Poly (methacrylic acid) (molecular weight 5,000 g / mol) in 5.6 kg of water and in the period of one hour while stirring with 0.42 kg of octylamine (20 mol% based on the acid functions of the polymer) dissolved in 1 l of isopropanol. The neutralization reaction of the amine with the acid was manifested by a slight increase in temperature.

The resulting reaction mixture was pumped continuously at 5.0 l / h through the reaction tube at a working pressure of 25 bar and a

Microwave power of 2.4 kW exposed, of which 88% were absorbed by the reaction. The residence time of the reaction mixture in the

Irradiation zone was about 48 seconds. When leaving the reaction tube, the reaction mixture had a temperature of 207 ° 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 198.degree. The reaction mixture was cooled to room temperature immediately after leaving the reaction section.

The reaction product was a homogeneous, colorless solution with a slightly increased viscosity compared to the unreacted polymer solution. After evaporation of the solvent resulted in a hygroscopic, sticky mass whose

IR spectrum for secondary amides characteristic bands at 1665 and

1540 cm ^-1 and a signal in the ¹ H NMR spectrum at 3.15 ppm (-NH-CH ₂ -) for a line broadening characteristic of polymeric amides of this methylene group adjacent to the amide nitrogen atom ω-standing CH ₃ group of the octyl at 0.8 - 0.9 ppm with the (H ₃ N ⁺ -CH ₂ -) grouping of the ammonium salt precursor at 2.9 ppm, a conversion of about 91% based on the amount of amine used determined.

In pure water, the resulting polymer is poorly soluble, but can be brought into solution by addition of small amounts of alkalis. The presence of the N-linked alkyl side groups causes weak association behavior, resulting in shear thinning behavior at low shear rates. Example 2: Amidation of poly (acrylic acid) with methylisopropylamine

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

Internal thermometer and pressure equalization became a solution of 1, 4 kg

Poly (acrylic acid) (molecular weight 5,000 g / mol) in 5.6 kg of water and heated to 40 ° C. At this temperature, over a period of one hour with stirring, a solution of 355 g of methyl isopropylamine (25 mol% based on the acid functions of the polymer) dissolved in 200 g of dimethylformamide was added. Again, the heat of neutralization showed a significant increase in temperature.

The reaction mixture thus obtained was continuously pumped at a working pressure of 33 bar at 4.8 l / h through the reaction tube and a

Exposed to microwave power of 2.3 kW, of which 89% were absorbed by the reaction mixture. The residence time of the reaction mixture in the

Irradiation zone was about 50 seconds. When leaving the reaction tube, the reaction mixture had a temperature of 215 ° 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 199.degree. The reaction mixture was cooled to room temperature immediately after leaving the reaction section.

The reaction product was a slightly yellowish solution of low viscosity. Evaporation of the solvent resulted in a viscous mass whose IR spectrum shows a characteristic of tertiary amides band at 1655 cm ^"1. The conversion determined according to the ¹ H-NMR method described under Experiment 1 was 89% of the amine used the content of methylisopropylamide groups was able to LCST behavior

(Increase in viscosity of a 5% aqueous solution) of the resulting polymer at 33-38 ° C are determined. Example 3: Amidation of poly (acrylic acid) with poly (ether) amine

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

Internal thermometer and pressure equalization became a solution of 4.0 kg

Poly (acrylic acid) (molecular weight 2,000 g / mol as a 50% solution in water) in 3 kg of water and 1 kg of isopropanol and heated to 35 ° C. At this temperature, 2.77 kg of Jeffamine ^® isopropanol (based on 10 mol% of the acid functions of the polymer) M-1000 over a period of one hour under stirring dissolved in 1 kg of added. Jeffamine M-1000 is a monofunctional poly (ether) amine prepared by reaction of methanol with 19 mol of ethylene oxide and 3 mol of propylene oxide and subsequent conversion of the terminal OH groups into amino groups.

The resulting reaction mixture was pumped continuously at 3.5 l / h through the reaction tube at a working pressure of 27 bar and a

Microwave power of 2.4 kW exposed, of which 91% were absorbed by the reaction mixture. The residence time of the reaction mixture in the

Irradiation zone was about 68 seconds. When leaving the reaction tube, the reaction mixture had a temperature of 225 ° C and was cooled directly to room temperature.

The reaction product was yellowish in color and exhibited a significantly increased viscosity (3000 mPas) compared with the unreacted polymer solution.

Brookfiled, 30 ° C). Evaporation of the water resulted in a viscous mass whose IR spectrum for secondary amides shows characteristic bands at 1660 and 1535 cm ^-1 . With the help of the integration of the ¹ H NMR signals of the

Nitrogen atoms adjacent CH ₃ groups of the propylene units in

Ammonium salt (1, 3 ppm) and in the amide (1.22 ppm) (starting material and product), a conversion of 75% of the polyetheramine used was estimated. Example 4: Attempt of amidation of poly (acrylic acid) with octylamine in water (comparative)

The procedure was analogous to experiment 1, but without the addition of an organic solvent. By vigorous stirring of the original, a homogeneous product solution could be prepared only with vigorous stirring and heating of the reaction mixture to 55 ° C.

The resulting reaction product showed after leaving the

Reaction apparatus distinct gel patches on polymer blocks with

indicate a different degree of modification.

Example 5: Attempt of amidation of poly (acrylic acid) with polyetheramine in water (comparative)

The procedure was analogous to experiment 3, but without the addition of an organic solvent. To set a comparable

Concentration of active ingredient in the reaction mixture, the amount of solvent used in Experiment 3 was replaced by water and added to the poly (acrylic acid). Upon addition of the poly (ether) amine to the poly (acrylic acid) solution heated to 35 ° C, the viscosity of the reaction mixture remarkably increased but remained pumpable. When pumping the reaction mixture through the microwave radiation exposed reaction tube, there was another, clear

Viscosity increase, causing the pump to stop and stop the experiment.

Claims

claims:

1. Continuous process for the implementation of synthetic

Poly (carboxylic acids) (A) containing at least 10 repeating structural units of the formula (I)

wherein

R ^{9 is} hydrogen, a C to C 1 alkyl group or a group of

formula

-CH ₂ -COOH

R ^{10 is} hydrogen or a C to C alkyl group

R ^{11 is} hydrogen, a C 1 to C ₄ alkyl group or -COOH

mean with amines (B) of the general formula (II)

HNR ¹ R ² (II) wherein

R ^{1 is} a hydrocarbon radical having 3 to 50 C atoms, which may be substituted or may contain heteroatoms, and

R ^{2 is} hydrogen or a hydrocarbon radical with 1 to

50 C atoms, which may be substituted or may contain heteroatoms, stand or

R ¹ and R ² together with the nitrogen atom to which they are attached, a

Form ring,

by a reaction mixture containing at least one synthetic Poly (carboxylic acid) (A) and at least one amine of the formula (II) in one

Solvent mixture, which water and, based on the weight of

2. The method of claim 1, wherein the poly (carboxylic acid) (A)

Homopolymer of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid, or a copolymer of two or more of these monomers.

3. The method of claim 1, wherein the poly (carboxylic acid) (A)

Copolymer of acrylic acid, methacrylic acid, crotonic acid, maleic acid,

Fumaric acid and / or itaconic acid, and at least one other ethylenically unsaturated monomer.

4. The method according to one or more of claims 1 to 3, wherein the poly (carboxylic acid) has an average molecular weight of at least 700 g / mol.

5. The method according to one or more of claims 1 to 4, wherein the amine is a primary amine.

6. The method according to one or more of claims 1 to 4, wherein the amine is a secondary amine.

7. The method according to one or more of claims 1 to 6, wherein R ^{1 is} an aliphatic radical.

8. The method according to one or more of claims 1 to 7, wherein R ^{2 is} an aliphatic radical.

9. The method according to one or more of claims 1 to 8, wherein the amine is a polyetheramine of the formula (III)

_ (R ³ -O) _n -R ⁴ (MI) wherein

R ^{3 is} an alkylene group having 2 to 6 carbon atoms and preferably 2 to

4 C atoms such as ethylene, propylene, butylene or

Mixtures thereof,

R ^{4 is} hydrogen, a hydrocarbon radical having 1 to 24 C atoms, an acyl radical of the formula -C (= O) -R ¹² , wherein R ^{12 is} a

Hydrocarbon radical having 1 to 50 carbon atoms, or a group of

Formula -R ³ -NR ⁵ R ⁶ ,

n is a number between 2 and 100, preferably between 3 and 50 and

especially between 4 and 25 such as between 5 and 10 and

R ⁵ , R ⁶ independently of one another represent hydrogen, an aliphatic radical having 1 to 24 C atoms and preferably 2 to 18 C atoms, an aryl group or heteroaryl group having 5 to 12 ring members, one

10. The method according to one or more of claims 1 to 9, wherein the amine is a polyamine of the formula (IV)

- [R ⁷ -N (R ⁸ )] _m - (R ⁸ ) (IV) represents an alkylene group having 2 to 6 C atoms and preferably having 2 to 4 C atoms, such as, for example, ethylene, propylene or mixtures thereof,

independently of one another for hydrogen, an alkyl or

Hydroxyalkyl radical having up to 24 carbon atoms such as 2 to 20 carbon atoms, a polyoxyalkylene radical - (R ³ -0) _p -R ⁴ , or a polyiminoalkylene radical - [R ⁷ -N (R ⁸ )] _q - (R ⁸ ), wherein R ³ , R ⁴ , R ⁷ and R ^{8 have} the meanings given above and q and p independently of one another are from 1 to 50 and

is a number from 1 to 20, and preferably from 2 to 10, such as three, four, five or six. The radicals of the formula (I) preferably contain 1 to 50, in particular 2 to 20, nitrogen atoms.

11. The method according to one or more of claims 1 to 10, wherein the reaction mixture used for reaction contains 10 to 99 wt .-% of a mixture of water and a water-miscible organic solvent.

12. The method according to one or more of claims 1 to, wherein the ratio between water and water-miscible organic solvent between 10: 1 and 1: 5.

13. The method according to one or more of claims 1 to 12, wherein the water-miscible solvent is a protic organic liquid.

14. The method of claim 13, wherein the water-miscible

Solvent is an alcohol.

15. The method according to one or more of claims 1 to 12, wherein the water-miscible solvent is an aprotic organic liquid.

16. The method of claim 15, wherein the water-miscible

Solvent is selected from formamide, Ν, Ν-dimethylformamide (DMF), Ν, Ν-dimethylacetamide, acetone, γ-butyrolactone, acetonitrile, sulfolane and

Dimethyl sulfoxide (DMSO).

17. The method according to one or more of claims 1 to 16, wherein the reaction is carried out at temperatures above 100 ° C.

18. The method according to one or more of claims 1 to 17, wherein the reaction mixture contains an acidic catalyst.

19. The method according to one or more of claims 1 to 18, wherein the reaction mixture contains a strong electrolyte.

20. The method according to one or more of claims 1 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 1 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 1 to 21, wherein the microwave applicator is formed as a cavity resonator.

23. The method according to one or more of claims 1 and 3 to 22, wherein the synthetic poly (carboxylic acids) (A) is a copolymer containing the derived from ethylenically unsaturated carboxylic acid structural units of the formula (I) in blockwise, alternating or random sequence ,

24. Hydrophobically modified synthetic poly (carboxylic acids), preparable by the process according to one or more of claims 1 to 23.