WO2010009993A1

WO2010009993A1 - Polyurethane dispersion containing an alkanolamine

Info

Publication number: WO2010009993A1
Application number: PCT/EP2009/058885
Authority: WO
Inventors: Gerd BÜLOW; Manfred Dargatz; Karl Häberle; Maria Teresa Hechavarria Fonseca; Michael Jahn; Darijo Mijolovic
Original assignee: Basf Se
Priority date: 2008-07-22
Filing date: 2009-07-13
Publication date: 2010-01-28

Abstract

The invention relates to an aqueous polyurethane dispersion containing an alkanolamine of the formula (I), where R¹ and R² are a C1 to C4 alkyl group, R³ is a hydrogen atom or a C1 to C4 alkyl group, and R⁴ and R⁵ are a C1 to C4 alkyl group independently of each other.

Description

Polyurethane dispersion containing an alkanolamine

description

The invention relates to an aqueous polyurethane dispersion containing an alkanolamine of the formula I.

wherein R 1 and R 2 are a C 1 to C 4 alkyl group, R 3 is a hydrogen atom or a C 1 to C 4 alkyl group, and R 4 and R 5 are each independently a C 1 to C 4 alkyl group.

Amines, especially tertiary amines, are used in aqueous polyurethane dispersions especially as neutralizing agents and dispersants. Polyurethane dispersions are used in particular as binders for coating compositions, sealants or adhesives.

Encyclopedia of Chemical Technology, Volume 2, 1992, pages 1 to 34 describes a variety of suitable alkanolamines. Of particular importance is 2-amino-2-methyl-1-propanol (AMP) or the corresponding dimethylated compound 2-dimethylamino-2-methyl-1-propanol (DMAMP), which is also described in G. N. Robinson, Proc. 3rd Intern. Congress on Paints, Vol. 1, 212 - 223, Sao Paulo 1993 and, moreover, have special significance as commercial products. Suitable alkanolamines are also described in EP-A-1 362 897. WO 2006/016991 and WO 2005/055720 disclose the use of alkanolamines as a biocide for aqueous systems.

The coatings, seals, impregnating compositions or bonds produced should have the best possible performance properties, in particular very good mechanical properties such as elasticity and hardness, but also the resistance to solvents and in particular water are desired in general. The resistance to water is often problematic especially for aqueous coating compositions, sealants and impregnating compounds or adhesives, since the binders and / or pigments used are generally water-soluble or water-dispersible prior to their use. Insufficient water resistance often leads to turbidity of the resulting coating, bonding or sealing, also called whitening. Furthermore, it is important, especially in the case of coatings and impregnations, that the masses used do not discolor under the influence of elevated temperature.

The object of the present invention, therefore, were coating compositions, sealing and impregnating compositions or adhesives based on polyurethane dispersions which contain alkanolamines having a good neutralizing and / or dispersing action; the performance properties, the solvent and in particular the water resistance of the resulting coatings, seals or bonds should be as good as possible.

Accordingly, the polyurethane dispersions and compositions defined above were found; Coating compositions, sealants, impregnating compounds or adhesives containing the polyurethane dispersions defined at the outset have also been found.

The polyurethane dispersions according to the invention comprise an alkanolamine of the above formula I.

In a preferred embodiment, it is an alkanolamine of the formula II (R3 = hydrogen, R4 = methyl and R5 = methyl):

In a preferred embodiment, R 1 and R 2 are a C 1 to C 4 alkyl group.

Most preferably, the alkyl group is a methyl group, i. R1 and R2 represent a methyl group.

A most preferred compound is therefore N, N-dimethyl-1-amino-2-methyl-2-propanol (R1 and R2 methyl).

The alkanolamines are obtainable in a known manner by reacting amines with epoxides of the formula

The polyurethane dispersions contain the alkanolamine preferably in an amount of 0.05 to 10 wt .-%, based on the dispersed polyurethane.

Particularly preferably, the minimum amount of alkanolamine is at least 0.1 wt .-%, most preferably at least 0.2 wt .-%. The maximum amount is preferably 7% by weight, in particular 5% by weight. All percentages are based on the polyurethane.

The aqueous polyurethane dispersion preferably contains a polyurethane composed of

a) diisocyanates,

b) Diols, of which

bi) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000, and

b2) 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol,

c) monomers which are different from the monomers (a) and (b) and have at least one isocyanate group or at least one isocyanate-reactive group which moreover carry at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water-dispersibility of the polyurethanes,

d) optionally other than the monomers (a) to (c) different polyvalent compounds having reactive groups which are alcoholic see hydroxyl groups, primary or secondary amino groups or isocyanate groups, and

e) optionally monovalent compounds other than the monomers (a) to (d), having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

Particular mention may be made as monomers (a) diisocyanates X (NCO) 2, wherein X is an aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms , Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diiso- cyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,2-bis (4-isocyanatocyclohexyl) propane, trimethylhexane diisocyanate, 1,4-diisocyanatobenzene , 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the isomers of bis- (4- isocyanatocyclohexyl) methane (HMDI) such as the trans / trans, the cis / cis and the cis / trans isomers and mixtures of these compounds.

Such diisocyanates are available commercially.

Particularly suitable mixtures of these isocyanates are the mixtures of the respective structural isomers of diisocyanatotoluene and diisocyanato-diphenylmethane; in particular, the mixture of 80 mol% of 2,4-diisocyanatotoluene and 20 mol% of 2,6-diisocyanatotoluene is suitable. Furthermore, the mixtures of aromatic isocyanates, such as 2,4-diisocyanatotoluene and / or 2,6-diisocyanatotoluene with aliphatic or cycloaliphatic isocyanates, such as hexamethylene diisocyanate or IPDI, are particularly advantageous, the preferred mixing ratio of the aliphatic to aromatic isocyanates being 4: 1 to 1: 4 is.

For the construction of the polyurethanes can be used as compounds in addition to the aforementioned also isocyanates, in addition to the free isocyanate groups further blocked isocyanate groups, e.g. Wear uretdione groups.

With regard to good film formation and elasticity, suitable diols (b) are primarily higher molecular weight diols (b1) which have a molecular weight of about 500 to 5,000, preferably about 1,000 to 3,000, g / mol.

The diols (b1) are, in particular, polyesterpolyols which are known, for example, from Ullmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 19, pages 62 to 65. Preference is given to using polyesterpolyols which are obtained by reacting dihydric alcohols with dibasic carboxylic acids. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and may optionally be substituted, for example by halogen atoms, and / or unsaturated. Examples which may be mentioned are: suberic acid, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids. Preference is given to dicarboxylic acids of the general formula HOOC- (CH 2) _y - COOH, where y is a number from 1 to 20, preferably an even number from 2 to 20, for example succinic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid.

As the polyhydric alcohols, e.g. Ethylene glycol, propane-1, 2-diol, propane-1, 3-diol, butane-1, 3-diol, butene-1, 4-diol, butyne-1, 4-diol, pentane-1, 5-diol, Neopentylglycol, bis (hydroxymethyl) cyclohexanes such as 1,4-bis (hydroxymethyl) cyclohexane, 2-methylpropane-1,3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, Dibutylene glycol and polybutylene glycols into consideration. Alcohols of the general formula HO- (CH 2) x -OH are preferred, where x is a number from 1 to 20, preferably an even number from 2 to 20. Examples of these are ethylene glycol, butane-1, 4-diol, hexane-1, 6-diol, octane-1, 8-diol and dodecane-1, 12-diol. Further preferred is neopentyl glycol.

Also included are polycarbonate diols, e.g. by reaction of phosgene with an excess of the mentioned as synthesis components for the polyester polyols low molecular weight alcohols, into consideration.

Also suitable are lactone-based polyesterdiols, which are homopolymers or copolymers of lactones, preferably hydroxyl-terminated addition products of lactones to suitable difunctional starter molecules. Suitable lactones are preferably those which are derived from compounds of the general formula HO- (CH 2) Σ-COOH, where z is a number from 1 to 20 and an H atom of a methylene unit by a C 1 to C 4 alkyl radical may be substituted. Examples are e-caprolactone, ß-propiolactone, gamma-butyrolactone and / or methyl epsilon-caprolactone and mixtures thereof. Suitable starter components are e.g. the low molecular weight dihydric alcohols mentioned above as the synthesis component for the polyesterpolyols. The corresponding polymers of epsilon-caprolactone are particularly preferred. Lower polyester diols or polyether diols can also be used as starters for the preparation of the lactone polymers. Instead of the polymers of lactones, it is also possible to use the corresponding, chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones.

In addition, suitable monomers (b1) are polyether diols. They are in particular by polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with itself, for example in the presence of BF 3 or by addition of these compounds, optionally in admixture or in succession, to starting components having reactive hydrogen atoms, such as alcohols or amines. For example, water, ethylene glycol, propane-1, 2-diol, propane-1, 3-diol, 1, 2-bis (4-hydroxy-diphenyl) propane or aniline available. Particularly preferred is polytetrahydrofuran having a molecular weight of 240 to 5000, and especially 500 to 4500. Also suitable are polyhydroxyolefins, preferably those having 2 terminal hydroxyl groups, for example a, -w-dihydroxypolybutadiene, a, -w-Dihydroxypolymethacrylester or a, -w-Dihydroxypolyacrylester as monomers (c1). Such compounds are known, for example, from EP-A 0622378. Further suitable polyols are polyacetals, polysiloxanes and alkyd resins.

The polyols can also be used as mixtures in the ratio of 0.1: 1 to 1: 9.

The hardness and modulus of elasticity of the polyurethanes can be increased if, as diols (b), low molecular weight diols (b2) having a molecular weight of from about 60 to 500, preferably from 62 to 200, g / mol are used in addition to the diols (b1).

The monomers (b2) used are in particular the synthesis components of the short-chain alkanediols mentioned for the preparation of polyester polyols, the unbranched diols having 2 to 12 carbon atoms and an even number of carbon atoms and pentane-1, 5-diol and neopentyl glycol to be favoured.

Preferably, the proportion of the diols (b1), based on the total amount of the diols (b) is 10 to 100 mol% and the proportion of the monomers (b2), based on the total amount of the diols (b) 0 to 90 mol%. The ratio of the diols (b1) to the monomers (b2) is particularly preferably 0.1: 1 to 5: 1, particularly preferably 0.2: 1 to 2: 1.

In order to achieve the water-dispersibility of the polyurethanes, the polyurethanes, in addition to the components (a), (b) and, if appropriate, (d) are monomers (c) which are different from components (a), (b) and (d) and which are at least one Isocyanate group or at least one isocyanate-reactive group and, moreover, at least one hydrophilic group or a group which can be converted into a hydrophilic Ie carry constructed. In the following text, the term "hydrophilic groups or potentially hydrophilic groups" is abbreviated to "(potentially) hydrophilic groups". The (potentially) hydrophilic groups react much more slowly with isocyanates than the functional groups of the monomers which serve to build up the polymer main chain.

The proportion of components having (potentially) hydrophilic groups in the total amount of components (a), (b), (c), (d) and (e) is generally such that the molar amount of (potentially) hydrophilic groups, based on the amount by weight of all monomers (a) to (e), 30 to 1000, preferably 50 to 500 and particularly preferably 80 to 300 mmol / kg. The (potentially) hydrophilic groups may be nonionic or, preferably, (potentially) ionic hydrophilic groups.

Suitable nonionic hydrophilic groups are, in particular, polyethylene glycol ethers of preferably 5 to 100, preferably 10 to 80, ethylene oxide repeat units. The content of polyethylene oxide units is generally 0 to 10, preferably 0 to 6 wt .-%, based on the amount by weight of all monomers (a) to (e).

Preferred monomers with nonionic hydrophilic groups are polyethylene oxide diols, polyethylene oxide monools and the reaction products of a polyethylene glycol and a diisocyanate which carry a terminally etherified polyethylene glycol radical. Such diisocyanates and processes for their preparation are given in the patents US-A 3,905,929 and US-A 3,920,598.

Ionic hydrophilic groups are especially anionic groups such as the sulfonate, the carboxylate and the phosphate group in the form of their alkali metal or ammonium salts and cationic groups such as ammonium groups, in particular protonated tertiary amino groups or quaternary ammonium groups.

Potentially ionic hydrophilic groups are, above all, those which can be converted by simple neutralization, hydrolysis or quaternization reactions into the above-mentioned ionic hydrophilic groups, e.g. Carboxylic acid groups or tertiary amino groups.

(Potentially) ionic monomers (c) are e.g. in Ullmann's Encyclopedia of Industrial Chemistry, 4th Edition, Volume 19, pp.311-313 and for example in DE-A 14 95 745 described in detail.

As (potentially) cationic monomers (c), especially monomers having tertiary amino groups are of particular practical importance, for example: tris (hydroxyalkyl) amines, N, N'-bis (hydroxyalkyl) alkylamines, N-hydroxyalkyl-dialkylamines , Tris- (aminoalkyl) -amines, N, N'-bis (aminoalkyl) -alkylamines, N-aminoalkyl-dialkylamines, wherein the alkyl radicals and alkanediyl moieties of these tertiary amines independently of one another consist of 1 to 6 carbon atoms. Furthermore, polyethers having tertiary nitrogen atoms and having preferably two terminal hydroxyl groups, such as those described, for example, are used. by the alkoxylation of two amine-containing hydrogen atoms, e.g. Methylamine, aniline or N, N'-dimethylhydrazine, in a conventional manner are accessible, into consideration. Such polyethers generally have a molecular weight between 500 and 6000 g / mol.

These tertiary amines are either with acids, preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids or strong organic see acids or converted by reaction with suitable quaternizing agents such as d- to Cβ-alkyl halides or benzyl halides, eg bromides or chlorides, in the ammonium salts.

Suitable monomers with (potentially) anionic groups are usually aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids which carry at least one alcoholic hydroxyl group or at least one primary or secondary amino group. Preference is given to dihydroxyalkyls, especially those having 3 to 10 carbon atoms, as are also described in US Pat. No. 3,412,054. In particular, compounds of the general formula (ci)

R ³

Ho-R ^L CR-OH (d)

COOH

in which R ¹ and R ² are a C to C4 alkanediyl unit and R ³ is a C to C ₄ - represents alkyl moiety and especially of dimethylolpropionic acid (DMPA) are preferred.

Also suitable are corresponding dihydroxysulfonic acids and dihydroxyphosphonic acids, such as 2,3-dihydroxypropanephosphonic acid.

Otherwise suitable are dihydroxyl compounds having a molecular weight above

500 to 10,000 g / mol with at least 2 carboxylate groups, which are known from DE-A 39 11 827. They are obtainable by reacting dihydroxyl compounds with tetracarboxylic acid dianhydrides such as pyromellitic dianhydride or cyclopentanetetracarboxylic dianhydride in a molar ratio of 2: 1 to 1:05 in a polyaddition reaction. Particularly suitable dihydroxyl compounds are the monomers (b2) listed as chain extenders and also the diols (b1).

Suitable monomers (c) with isocyanate-reactive amino groups are amino carboxylic acids such as lysine, β-alanine or the adducts of aliphatic diprimary diamines mentioned in DE-A 20 34 479 to α, β-unsaturated carboxylic or sulfonic acids into consideration.

Such compounds obey, for example, the formula (C2)

H ₂ NR ¹ NH-RX ( ^c2 ) in the

R ⁴ and R ⁵ independently represent a C to Cε alkanediyl unit, preferably ethylene, and X represents COOH or SO ₃ H. Particularly preferred compounds of the formula (C2) are N- (2-aminoethyl) -2-aminoethanecarboxylic acid and also N- (2-aminoethyl) -2-aminoethanesulfonic acid or the corresponding alkali metal salts, Na being particularly preferred as the counterion.

Further particularly preferred are the adducts of the abovementioned aliphatic diprimary diamines with 2-acrylamido-2-methylpropanesulfonic acid, as described, for example, in US Pat. in DE Patent 19 54 090 are described.

If monomers having potentially ionic groups are used, their conversion into the ionic form can take place before, during, but preferably after the isocyanate polyaddition, since the ionic monomers are often difficult to dissolve in the reaction mixture. The sulfonate or carboxylate groups are particularly preferably present in the form of their salts with an alkali metal ion or an ammonium ion as the counterion.

In the context of this invention particularly preferred polyurethane dispersions are those in which the polyurethane has a content of carboxylic acid groups, in particular by selecting appropriate compounds (d) according to the above formula, most preferably by the concomitant use of DMPA.

The monomers (d), which are different from the monomers (a) to (c) and which are optionally also constituents of the polyurethane, generally serve for crosslinking or chain extension. They are generally more than dihydric non-phenolic alcohols, amines having 2 or more primary and / or secondary amino groups and compounds which carry one or more primary and / or secondary amino groups in addition to one or more alcoholic hydroxyl groups.

Alcohols of a higher valence than 2, which can serve to set a certain degree of branching or crosslinking, are known, for example. Trimethylolpropane, glycerine or sugar.

Also suitable are monoalcohols which, in addition to the hydroxyl group, carry a further isocyanate-reactive group, such as monoalcohols having one or more primary and / or secondary amino groups, e.g. Monoethanolamine.

Polyamines having 2 or more primary and / or secondary amino groups are used especially when the chain extension or crosslinking is to take place in the presence of water, since amines usually react faster than alcohols or water with isocyanates. This is often necessary when aqueous dispersions of crosslinked polyurethanes or high molecular weight polyurethanes are used. wishes to be. In such cases, the procedure is to prepare prepolymers with isocyanate groups, to rapidly disperse them in water and then to chain extend or crosslink them by adding compounds containing several isocyanate-reactive amino groups.

Amines suitable for this purpose are generally polyfunctional amines of the molecular weight range from 32 to 500 g / mol, preferably from 60 to 300 g / mol, which contain at least two amino groups selected from the group of primary and secondary amino groups. Examples of these are diamines such as diaminoethane, diamino propanes, diaminobutanes, diaminohexanes, piperazine, 2,5-dimethylpiperazine, amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophoronediamine, IPDA), 4,4'-diaminodicyclo - hexylmethane, 1, 4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylenetriamine or 1, 8-diamino-4-aminomethyloctan.

The amines may also be in blocked form, e.g. in the form of the corresponding ketimines (see, for example, CA-A 1 129 128), ketazines (see, for example, US-A 4,269,748) or amine salts (see US-A 4,292,226). Also oxazolidines, as used for example in US Pat. No. 4,192,937, are blocked polyamines which can be used for the preparation of the polyurethanes according to the invention for chain extension of the prepolymers. When using such capped polyamines they are generally mixed with the prepolymers in the absence of water and this mixture is then mixed with the dispersion water or a part of the dispersion water, so that the corresponding polyamines are hydrolytically released.

Preference is given to using mixtures of di- and triamines, particularly preferably mixtures of isophoronediamine (IPDA) and diethylenetriamine (DETA).

The polyurethanes preferably contain from 1 to 30, particularly preferably from 4 to 25, mol%, based on the total amount of components (b) and (d), of a polyamine having at least 2 isocyanate-reactive amino groups as monomers (d).

For the same purpose higher than divalent isocyanates can also be used as monomers (d). Commercially available compounds are, for example, the isocyanurate or the biuret of hexamethylene diisocyanate.

Monomers (e), which are optionally used, are monoisocyanates, monohydric alcohols and monoprimary and secondary amines. In general, their share at most 10 mol%, based on the total molar amount of the monomers. These monofunctional compounds usually carry further functional groups, such as olefinic groups or carbonyl groups, and serve to introduce functional groups into the polyurethane, which make possible the dispersion or crosslinking or further polymer-analogous reaction of the polyurethane. Suitable for this purpose are monomers such as isopropenyl-α, α-dimethylbenzyl isocyanate (TMI) and esters of acrylic or methacrylic acid such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

In the field of polyurethane chemistry, it is generally known how the molecular weight of the polyurethanes can be adjusted by selecting the proportions of the monomers which are reactive with one another and the arithmetic mean of the number of reactive functional groups per molecule.

Normally, the components (a) to (e) and their respective molar amounts are chosen so that the ratio A: B with

A) the molar amount of isocyanate groups and

B) the sum of the molar amount of the hydroxyl groups and the molar amount of the functional groups which can react with isocyanates in an addition reaction

0.5: 1 to 2: 1, preferably 0.8: 1 to 1, 5, more preferably 0.9: 1 to 1, 2: 1. Most preferably, the ratio A: B is as close as possible to 1: 1.

The monomers (a) to (e) used carry on average usually 1.5 to 2.5, preferably 1.9 to 2.1, particularly preferably 2.0 isocyanate groups or functional groups which can react with isocyanates in an addition reaction ,

The polyaddition of components (a) to (e) for the preparation of the polyurethane present in the aqueous dispersions of the invention is carried out at reaction temperatures of 20 to 18O ⁰ C, preferably 50 to 15O ⁰ C under atmospheric pressure or under autogenous pressure.

The required reaction times are in the range of 1 to 20 hours, in particular in the range of 1, 5 to 10 hours. It is known in the field of polyurethane chemistry how the reaction time is affected by a variety of parameters such as temperature, concentration of monomers, reactivity of the monomers.

Rührkessel come into consideration as polymerization, especially when provided by the concomitant use of solvents for a low viscosity and good heat dissipation. Preferred solvents are immiscible with water indefinitely, have a boiling point at atmospheric pressure of 40 to 100 ⁰ C and do not react or only slowly with the monomers.

Most often, the dispersions are prepared by one of the following methods:

After the "acetone process" C ^0-boiling solvent is removed from the components (a) to (c) an ionic ULTRASONIC polyurethane in a solvent miscible with water and at normal pressure under 100th Add enough water to form a dispersion in which water is the coherent phase.

The "prepolymer mixing process" differs from the acetone process in that it does not produce a fully reacted (potentially) ionic polyurethane, but first a prepolymer bearing isocyanate groups. The components are chosen so that the ratio A: B is greater than 1, 0 to 3, preferably 1, 05 to 1, 5. The prepolymer is first dispersed in water and then optionally crosslinked by reaction of the isocyanate groups with amines carrying more than 2 isocyanate-reactive amino groups, or chain-extended with amines bearing 2 isocyanate-reactive amino groups. Chain extension also occurs when no amine is added. In this case, isocyanate groups are hydrolyzed to amino groups, which react with remaining isocyanate groups of the prepolymers with chain extension.

Usually, if a solvent was used in the preparation of the polyurethane, most of the solvent is removed from the dispersion, for example by distillation at reduced pressure. The dispersions preferably have a solvent content of less than 10% by weight and are particularly preferably free from solvents.

The polyurethane dispersions generally have a solids content of 10 to 75, preferably from 20 to 65 wt .-% and a viscosity of 10 to 500 m Pas (measured at a temperature of 2O ⁰ C and a shear rate of 250 S " ¹ ).

The polyurethane in a preferred embodiment contains hydrophilic groups, in particular those selected from carboxyl groups, hydroxyl groups, amino groups and carboxamide groups. The content of these hydrophilic groups is in particular 0.001 to 0.5 mol per 100 g of polymer. The content is preferably at least 0.005 mol, particularly preferably at least 0.008 mol and not more than 0.2 mol, in particular not more than 0.1 mol, very particularly preferably not more than 0.05 or 0.03 mol per 100 g / polymer. Particularly preferably, at least 20 mol%, particularly preferably at least 50 mol% of the total molar amount of these groups are carboxyl groups.

Carboxyl groups are understood as meaning both carboxylic acid groups and their salts.

The polyurethane dispersions according to the invention can be used in particular as a coating composition, sealant, impregnating composition or adhesive.

The coating compositions, sealants, impregnating compounds or adhesives may contain, in addition to the alkanolamine and the polyurethane dispersion, further constituents. However, they can also consist solely of the alkanolamine and the aqueous polyurethane dispersion.

Adhesives, in particular pressure-sensitive adhesives, can e.g. Fillers, colorants, leveling agents, thickeners or tackifiers (tackifying resins) Tackifiers are, for example, natural resins, such as rosin resins and their derivatives resulting from disproportionation or isomerization, polymerization, dimerization, hydrogenation, which can be used in their salt form (with, for example, mono- or polyhydric Alcohols used for esterification may be monohydric or polyhydric, for example, methanol, ethanediol, diethylene glycol, triethylene glycol, 1,2,3-propanethiol, pentaerythritol.

Sealants may in particular contain fillers. Furthermore, they contain aids to increase the stability, e.g. Thickener to increase the viscosity.

Particularly suitable coating compositions are coating materials which contain pigments and / or fillers. Examples of these are in particular plasters and paint compounds, both for the interior and for outdoor applications. Particularly preferred are coating compositions for outdoor applications. In particular, coating compositions or impregnating compositions for textiles and in particular leather are also considered.

As pigments, in particular inorganic, particulate pigments may be mentioned. Consider, for example, White pigments such as titanium dioxide, preferably in the rutile form, barium sulfate or zinc oxide, or color pigments such as iron oxides, carbon black, luminescent pigments, zinc yellow, zinc green or ultramarine.

Fillers which may be mentioned in particular inorganic, particulate fillers. Suitable examples are aluminosilicates, such as feldspars, silicates, such as kaolin, talc, Mica, wollastonite, magnesite, alkaline earth carbonates such as calcium carbonate, for example in the form of calcite or chalk, magnesium carbonate, dolomite, alkaline earth sulfates such as calcium sulfate, silica, Plastorit®, etc. The fillers may be used singly or in admixture.

The coating compositions preferably contain 10 to 1000 parts by weight of pigments, fillers or mixtures of pigments and fillers per 100 parts by weight of binder. When used as (highly filled) interior paint, they particularly preferably contain from 300 to 800 parts by weight and as gloss coating 10 to 100 parts by weight of pigments, fillers or mixtures of pigments and fillers per 100 parts by weight of binder.

Further constituents which may be contained in the coating compositions are e.g. Antifreeze, leveling agent and thickener.

The polyurethane dispersions or coating compositions, sealants, impregnating compositions or adhesives of the invention can be processed by conventional methods, or be used in the usual way as an adhesive sealant, impregnating or coating material. In general, the composition is applied to the desired substrate or surface to be coated, and then the solvent is removed, e.g. by drying at ambient temperature or at elevated temperatures.

The above alkanolamines of the formula I are very suitable as neutralizing and / or dispersing agents in the polyurethane dispersions. They have a similar base strength as AMP (other amines have lower base strength and are therefore needed in larger amounts to adjust the pH). The compositions according to the invention may be completely or partially neutralized with the alkanolamine; The pH of the compositions may be in particular 5 to 9. Furthermore, the performance properties, the solvents, chemicals and in particular the water resistance of the resulting coatings, seals, impregnations or bonds are very good, also in comparison to the AMP or DMAMP. A blushing is not or hardly observed in the compositions of the invention.

In particular, little yellowing is observed at elevated temperatures. Examples:

Abbreviations:

DETA diethylenetriamine

DMEA dimethylethanolamine

DMPA dimethylolpropionic acid

HDI hexamethylene diisocyanate-1, 6

IPDA isophorone diamine

TEA triethylamine

Inventive alkanolamine (abbreviated A1) N, N-dimethyl-1-amino-2-methyl-2-propanol

example 1

In a stirred flask equipped with thermometer and reflux condenser, 400 g (0.20 mol) of a polyester of OH number 56 from hexanediol-1, 6, neopentyl glycol and adipic acid, 20.1 g (0.15 mol) of DMPA and 150 g of acetone Heated to 50 ⁰ C. To this was added 12.6 g (0.67 mol) of HDI and heated to 67 ° C. After 240 minutes, it was diluted with 550 g of acetone and cooled to 25 ° C. The NCO content of the solution became too

2.09% determined (calculated: 2.18%). To the solution was added 11.9 g (0.10 mol) of Al and 34.0 g (0.20 mol) of IPDA. After 5 minutes, it was dispersed with 650 g of water. Immediately afterwards, a mixture of 8.2 g (0.08 mol) of DETA and 50 g of water was added. After the acetone was distilled, a finely divided PUD having a solids content of 44.8% was obtained.

Example 2 In a stirred flask with thermometer and reflux condenser, 500 g (0.25 mol) of a polyester of OH number 56 from hexanediol-1,6-neopentyl glycol and adipic acid, 20.1 g (0.15 mol) DMPA and 120 g Heated acetone to 50 ⁰ C. To this was added 87.4 g (0.52 mol) of HDI and heated to 67 ° C. After 240 minutes, it was diluted with 580 g of acetone and cooled to 32 ° C. The NCO content of the solution was determined to be 0.78% (calculated: 0.77%). To the solution was added 14.75 g (0.126 mol) of Al. After 5 minutes, it was dispersed with 900 g of water. Immediately afterwards, a mixture of 8.2 g (0.08 mol) of DETA and 50 g of water was added. After the acetone was distilled, a finely divided PUD having a solids content of 40.0% was obtained. Example 3

In a stirred flask with thermometer and reflux condenser, 500 g (0.25 mol) of a polyester of OH number 56 from hexanediol-1, 6, neopentyl glycol and adipic acid, 20.1 g (0.15 mol) of DMPA and 120 g of acetone Heated to 50 ⁰ C. To this was added 87.4 g (0.52 mol) of HDI and heated to 67 ° C. After 240 minutes, it was diluted with 580 g of acetone and cooled to 32 ° C. The NCO content of the solution was determined to be 0.86% (calculated: 0.77%). To the solution was added 17.35 g (0.148 mol) of Al. After 5 minutes, it was dispersed with 900 g of water. Immediately afterwards, a mixture of 7.0 g (0.068 mol) of DETA and 50 g of water was added. After the acetone was distilled, a finely divided PUD having a solids content of 40.0% was obtained.

Example 4 In a stirred flask with thermometer and reflux condenser, 400 g (0.20 mol) of a polyester of OH number 56 from hexanediol-1,6-neopentylglycol and adipic acid, 20.1 g (0.15 mol) of DMPA and 150 g acetone heated to 50 ⁰ C. To this was added 12.6 g (0.67 mol) of HDI and heated to 67 ° C. After 240 minutes, it was diluted with 550 g of acetone and cooled to 25 ° C. The NCO content of the solution was determined to be 2.20% (calculated: 2.18%). To the solution was added 11.9 g (0.10 mol) of Al and 34.0 g (0.20 mol) of IPDA. After 5 minutes, it was dispersed with 650 g of water. Immediately afterwards, a mixture of 8.2 g (0.08 mol) of DETA and 50 g of water was added. After distillation of the acetone, a finely divided PUD with 40.6% solids content was obtained.

Comparative Examples

Comparative Example C1

Example 1 was repeated except that 10.1 g (0.10 mol) of TEA were used instead of A1.

Comparative Example C2 Example 2 was repeated except that 11.11 g (0.10 mol) of DMEA were used in place of the A1.

Comparative Example C3

Example 2 was repeated except that 12.7 g (0.126 mol) of TEA were used instead of A1. Comparative Example V4

Example 1 was repeated except that 14.7 g (0.10 mol) of DMEA were used in place of the A1.

Of all the dispersions, films of about 1 mm thickness were cast and stored for 48 hours at room temperature.

Thereafter, the films were stored for 4 hours in a convection oven UNE 200 from Memmert at 120 ⁰ C. The discoloration was assessed by means of an iodine color scale according to DIN 6162 with the following results:

Claims

claims

1. Aqueous polyurethane dispersion containing an alkanolamine of the formula I.

2. Aqueous polyurethane dispersion according to claim 1, characterized in that it is an alkanolamine of the formula II

where R1 and R2 have the above meaning.

3. Aqueous polyurethane dispersion according to claim 1 or 2, characterized in that R1 and R2 represent a C1 to C4 alkyl group.

4. Aqueous polyurethane dispersion according to any one of claims 1 to 3, characterized in that R1 and R2 represent a methyl group.

5. Aqueous polyurethane dispersion according to any one of claims 1 to 4, characterized in that it contains the alkanolamine in amounts of 0.05 to 10 wt.%, Based on the polyurethane.

6. Aqueous polyurethane dispersion according to any one of claims 1 to 4, characterized in that the dispersed polyurethane contains carboxylic acid groups.

7. Use of the aqueous polyurethane dispersions according to one of claims 1 to 6 as or in coating compositions, sealants, impregnating compounds or adhesives.

8. Coatings, seals, impregnations or adhesives obtainable by use according to claim 7.