Aromatic polyurethane-urea dispersions

The invention relates to the production of polyurethane-urea dispersions containing 4,4'-diphenylmethane diisocyanate (4,4'-MDI) and their use in coatings.

Owing to a strengthening of ecological and associated legal requirements, polyurethane-urea dispersions are increasingly being used as coating agents nowadays as a way of reducing solvent emissions. An overview of the various types and production processes can be found for example in Houben-Weyl: "Methoden der Organischen Chemie, Vol. E20, p. 1659-1692" or in "Ullmann's Encyclopaedia of Industrial Chemistry" (1992), Vol. A21, p. 667-682. In the following text dispersions containing urea groups as well as urethane groups are also classed as polyurethane dispersions (PUDs).

By virtue of their greater resistance to environmental influences, polyurethane-urea dispersions based on aliphatic polyisocyanates are most commonly used. However, there are also applications in which binders based largely on aromatic polyisocyanates play an important part, such as for example adhesive applications, textile coatings, etc. The diisocyanates toluylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) available in industry and the corresponding polymeric homologues are mostly used here.

Depending on the process used, however, the production of diisocyanates proceeds in such a non-specific manner that a mixture of several isomers is always obtained, which is optionally purified by distillation or used directly as a mixture of isomers. In the production of TDI, for example, the monomer forms as a mixture of the corresponding 2,4- and 2,6-diisocyanate isomers. In the case of MDI there are 4,4'-, 2,2'- and 2,4'-isomers, which are used either in the form of the mixture of isomers or as pure components. From an economic and ecological perspective it must be borne in mind that if certain isomers are used by preference, the processability of the other isomers should be ensured. Owing to the higher vapour pressure and higher toxicity of TDI, preference in this respect should be given to MDI. Given the symmetrical structure of 4,4'-MDI and the associated more favourable crystallisation properties of - -

the corresponding urethane and urea group, the exclusive use of this polyisocyanate in the production of aqueous polyurethane binders would be desirable.

For many applications a further functionalization of the PU backbone is prerequisite because this opens additional possibilities to increase the final properties of a coating. A rather common process in e.g. textile coatings with polyurethane dispersions is the addition of water dispersible polyisocyanates in the coating formulation. During the drying step the free NCO groups of the polyisocyanate can react with the substrate or with the polyurethane to increase the adhesive or cohesive strength of the final coating layer. A hydroxy- or carboxy functionalized polyurethane dispersion supports the reaction between the polyurethane and the polyisocyanate.

EP 0 581 159 by Munzmay et al. describes polyurethane-urea dispersions based on aromatic diisocyanates and a polyether and having an average molar mass greater than 1500 g-mol ^"1 , the concentration of urea and urethane groups lying within a certain value range. These coating agents can be used as an anchor coat for the coating of leather and also textiles, but are based on TDI.

US 6,524,978 describes aromatic polyurethane-urea dispersions for carpet backing applications which are dispersed using external emulsifiers and contain at least one glycerol monoester as polyol. The disadvantage here is the use of an external emulsifier that is capable of migration and of the glycerol monoester, which creates a moisture barrier. This is not desirable in textile applications, as coated textiles should be permeable to water vapour in the interests of wearing comfort.

US 7,240,371 describes a coated elastic textile wherein a polyurethane-urea dispersion is used for coating which is substantially based on a mixture of 4,4'-MDI and 2,4'-MDI and which contains a dialkylamine as blocking agent. The use of the blocking agent, which is only eliminated at elevated temperature and hence leads to increased emissions, is disadvantageous.

EP 220 000 describes aqueous polyurethane dispersions which are characterised in that they contain at least 5% 2,4'-MDI. The disadvantage of the dispersions according to the invention is the use of NMP as a solvent, which can no longer be _ _

removed by distillation. Embodiment example 3D with pure 4,4'-MDI leads not to a stable dispersion but to the gelation of the reaction batch.

US 6,316,108 and US 20070208133 disclose hydrophilic polyurethane dispersions which are characterised in that they are produced by means of external emulsifiers and are free from ionic groups. Although these publications disclose embodiment examples based on pure 4,4'-MDI, they have the disadvantage of using external emulsifiers, which can reduce adhesion, and of exclusively non-ionic internal hydrophilisation, which causes the resulting dispersions to be less thermally stable.

US 2008/0004395 describes polyurethane dispersions which are ionically hydrophilised internally and which in addition to an external emulsifier also contain an isocyanate-reactive blocking agent, which must first be eliminated at elevated temperature to allow subsequent crosslinking.

US 2009/0215954 discloses aqueous dispersions which are based on a mixture of at least two polyisocyanates, one polyisocyanate being 2,2'-MDI. WO 1981/02894 claims carboxyl-group-containing, aqueous polyurethane systems which are synthesised inter alia from aromatic polyisocyanates, a polyamine and a blocking agent. The use of a blocking agent is disadvantageous as the blocking agent has to be eliminated again, leading to additional emissions.

The object of the present invention is the production of stable carboxy-functionalized 4,4'-MDI-containing polyurethane-urea dispersions (PUDs) which are characterised in that they are free from solvents, blocking agents and external emulsifiers and when used as a coating on textile substrates they achieve outstanding adhesion values.

Surprisingly it has now been found that stable, emulsifier-free 4,4'-MDI-containing PUDs are obtainable which are characterised in that they are simultaneously anionically and non-ionically hydrophilised internally.

The aqueous polyurethane dispersions according to the invention contain a polyurethane polymer consisting of - -

a) 5 to 55 wt.% of 4,4'-diphenylmethane diisocyanate, b) 43.4 to 75 wt.% of one or more polyhydroxy compounds having a molar mass M _n of 400 g/mol to 8000 g/mol and a functionality of 1.5 to 6, c) 1 to 10 wt.% of one or more mono functional isocyanate-reactive non-ionic hydrophilising agents, d) 0.5 to 7 wt.% of one or more ionic or potentially ionic hydrophilising agents containing a carboxy function, e) 0.1 to 3.0 wt.% of one or more polyamine compounds having a molar mass of 32 to 400 g/mol, f) optionally a neutralising amine, g) optionally polyhydroxy compounds having a functionality of 2 to 3 and an average molar mass M _n of 62 to 200 g/mol, wherein the stated amounts relate to all structural components of the polyurethane polymer.

Preferably the aqueous polyurethane dispersions according to the invention contain a polyurethane polymer consisting of h) 5 to 55 wt.%) of 4,4'-diphenylmethane diisocyanate, i) 43.4 to 75 wt.% of one or more polyhydroxy compounds having a molar mass M _n of 400 g/mol to 8000 g/mol and a functionality of 1.5 to 6, j) 1 to 10 wt.% of one or more mono functional isocyanate-reactive non-ionic hydrophilising agents, k) 0.5 to 7 wt.% of one or more ionic or potentially ionic hydrophilising agents containing a carboxy function,

1) 0.1 to 3.0 wt.% of one or more polyamine compounds having a molar mass of 32 to 400 g/mol, m) optionally a neutralising amine, n) optionally polyhydroxy compounds having a functionality of 2 to 3 and an average molar mass M _n of 62 to 200 g/mol, wherein the stated amounts relate to all structural components of the polyurethane polymer.

Component a) is 4,4'-diphenylmethane diisocyanate.

The aqueous polyurethane dispersion preferably has a solids content, i.e. a content of polyurethane polymers, in the range from 20 to 60 wt.%, particularly preferably in the range from 25 to 55 wt.%, most particularly preferably in the range from 30 to 50 wt.%.

The polyurethane dispersion preferably has a viscosity in the range from 10 to 1000 mPa.s, particularly preferably in the range from 20 to 700 mPa.s, most particularly preferably in the range from 50 to 500 mPa.s, measured in accordance with DIN EN ISO 3219/A.3.

The polyurethane polymer preferably has an acid value in the range from 1 to 25, particularly preferably in the range from 4 to 20, most particularly preferably in the range from 6 to 15, measured in accordance with DIN EN ISO 2114.

Component a) is preferably present in amounts from 13.5 to 48 wt.%, particularly preferably 21 to 43 wt.%, relative to all structural components of the polyurethane polymer.

The polyurethane polymer preferably does not consist of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate or mixtures thereof.

Polymeric polyols for use as compounds b) have a molecular weight M _n of 400 to 8000 g/mol, preferably 400 to 6000 g/mol and particularly preferably 400 to 3000 g/mol. Their hydroxyl value is 22 to 400 mg KOH/g, preferably 30 to 300 mg KOH/g and particularly preferably 40 to 250 mg KOH/g, and they have an OH functionality of 1.5 to 6, preferably 1.8 to 3 and particularly preferably 1.9 to 2.1. _ _

Component b) is preferably present in amounts from 48.8 to 70 wt.%, particularly preferably 52.2 to 65 wt.%, relative to all structural components of the polyurethane polymer.

Polyols b) within the meaning of the present invention are the organic polyhydroxyl compounds known in polyurethane paint technology, such as for example the conventional polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester polyacrylate polyols and polyurethane polyacrylate polyols, polyurethane polyester polyols, polyurethane polyether polyols, polyurethane polycarbonate polyols, polyester polycarbonate polyols, phenol/formaldehyde resins, alone or in mixtures. Polyester polyols, polyether polyols or polycarbonate polyols are preferred, with polyether polyols being particularly preferred.

Suitable polyether polyols are for example the polyaddition products of styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and the co-addition and graft products thereof, as well as the polyether polyols obtained by condensation of polyhydric alcohols or mixtures thereof and by alkoxylation of polyhydric alcohols, amines and amino alcohols.

Suitable hydroxy-functional polyethers have OH functionalities of 1 .5 to 6.0, preferably 1.8 to 3.0, OH values of 50 to 700, preferably 100 to 600 mg KOH/g solid, and molecular weights M _n of 106 to 4000 g/mol, preferably 200 to 3500, such as for example alkoxylation products of hydroxy-functional starter molecules such as ethylene glycol, propylene glycol, butanediol, hexanediol, trimethylolpropane, glycerol, pentaerythritol, sorbitol or mixtures thereof and also other hydroxy- functional compounds with propylene oxide or butylene oxide. Polypropylene oxide polyols and polytetramethylene oxide polyols with a molecular weight of 300 to 4000 g/mol are preferred as the polyether component b). With correspondingly high OH contents the particularly low-molecular-weight polyether polyols can be water- soluble. However, water-insoluble polypropylene oxide polyols and polytetramethylene oxide polyols having a molecular weight of 500 to 3000 g/mol and mixtures thereof are particularly preferred. - -

Very suitable examples of polyester polyols b) are the polycondensates of diols and optionally triols and tetraols and dicarboxylic and optionally tricarboxylic and tetracarboxylic acids or hydroxycarboxylic acids or lactones known per se. In place of the free polycarboxylic acids, the corresponding polycarboxylic anhydrides or corresponding polycarboxylic acid esters of low alcohols can also be used to produce the polyesters. Examples of suitable diols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, a l s o 1 , 2-propanediol, 1,3-propanediol, butanediol(l,3), butanediol(l,4), hexanediol(l,6) and isomers, neopentyl glycol or hydro xypivalic acid neopentyl glycol ester, the last three cited compounds being preferred. In order to achieve a functionality of < 2, small amounts of polyols having a functionality of 3 can optionally be used, trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate being cited by way of example.

Suitable dicarboxylic acids are for example phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexane dicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methyl succinic acid, 3,3-diethyl glutaric acid, 2,2-dimethyl succinic acid. Anhydrides of these acids can likewise be used where they exist. For the needs of the present invention the anhydrides are accordingly encompassed by the expression "acid". Monocarboxylic acids, such as benzoic acid and hexane carboxylic acid, can also be used, provided that the average functionality of the polyol is > 2. Saturated aliphatic or aromatic acids are preferred, such as adipic acid or isophthalic acid. Trimellitic acid can be mentioned here as a polycarboxylic acid which can optionally be incorporated in smaller amounts.

Hydroxycarboxylic acids which can be incorporated as reactants in the production of a polyester polyol having terminal hydroxyl groups are for example hydroxycaproic acid, hydroxybutyric acid, hydro xydecanoic acid, hydroxy stearic acid and the like. Possible lactones are inter alia ε-caprolactone, butyrolactone and homologues. Polyester polyols b) based on butanediol and/or neopentyl glycol and/or hexanediol and/or ethylene glycol and/or diethylene glycol with adipic acid and/or phthalic acid and/or isophthalic acid are preferred. Polyester polyols b) based on butanediol and/or neopentyl glycol and/or hexanediol with adipic acid and/or phthalic acid are particularly preferred.

The suitable polycarbonate polyols are obtainable by reacting carbonic acid derivatives, for example diphenyl carbonate, dimethyl carbonate or phosgene, with diols. Examples of such diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butan e dio l , 1 , 6-hexanediol, 1,8-octanediol, neopentyl glycol, 1 ,4-bishydroxymethyl cyclohexane, 2 -methyl- 1,3-propanediol,

2,2,4-trimethylpentanediol-l,3, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, tetrabromobisphenol A but also lactone- modified diols. The diol component preferably contains 40 to 100 wt.% of 1 ,6- hexanediol and/or hexanediol derivatives, preferably those having ether or ester groups in addition to terminal OH groups, for example products obtained by reacting 1 mol of hexanediol with at least 1 mol, preferably 1 to 2 mol, of ε-caprolactone or by etherifying hexanediol with itself to form the dihexylene or trihexylene glycol. Polyether-polycarbonate polyols can also be used.

Polycarbonate polyols b) based on dimethyl carbonate and hexanediol and/or butanediol and/or ε-caprolactone are preferred. Polycarbonate polyols based on dimethyl carbonate and hexanediol and/or ε-caprolactone are most particularly preferred.

Overall, however, polyether polyols are particularly preferred as component b).

Suitable compounds c) having a non-ionically hydrophilising action are for example monohydric polyalkylene oxide polyether alcohols having a statistical mean of 5 to 70, preferably 7 to 55 ethylene oxide units per molecule, such as can be obtained in a manner known per se by alkoxylation of suitable starter molecules (e.g. in Ullmanns Encyclopadie der technischen Chemie, 4th Edition, Volume 19, Verlag Chemie, Weinheim p. 31-38). - -

Suitable starter molecules are for example saturated monoalcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, n-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, cyclohexanol, the isomeric methylcyclohexanols or hydroxymethylcyclohexane, 3-ethyl-3-hydroxymethyloxetane or tetrahydrofurfuryl alcohol, diethylene glycol monoalkyl ethers such as for example diethylene glycol monobutyl ether, unsaturated alcohols such as allyl alcohol, 1,1 -dimethyl allyl alcohol or oleic alcohol, aromatic alcohols such as phenol, the isomeric cresols or methoxyphenols, araliphatic alcohols such as benzyl alcohol, anisic alcohol or cinnamic alcohol, secondary monoamines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, bis-(2-ethylhexyl)amine, N-methyl- and N-ethylcyclohexylamine or dicyclohexylamine and heterocyclic secondary amines such as morpholine, pyrrolidine, piperidine or l H-pyrazole. Preferred starter molecules are saturated monoalcohols. Diethylene glycol monobutyl ether is particularly preferably used as the starter molecule.

Suitable alkylene oxides for the alkoxylation reaction are in particular ethylene oxide and propylene oxide, which can be used in the alkoxylation reaction in any sequence or in a mixture.

The molar mass M _n of these structural units is 300 g/mol to 6000 g/mol, preferably 500 g/mol to 4000 g/mol and particularly preferably 750 g/mol to 3000 g/mol with a functionality of 1.

Component c) is preferably present in amounts from 2 to 8 wt.%, particularly preferably 3 to 7 wt.%, relative to all structural components of the polyurethane polymer. Suitable non-ionically hydrophilising, monofunctional compounds d) of this type are for example monofunctional alkoxypolyethylene glycols such as for example methoxypolyethylene glycols (MPEG Carbowax ^® 2000 or methoxy PEG-40, molecular weight range 1800 to 2200, The Dow Chemical Company), monofunctional polyether monoalkyl ethers such as for example LB 25 synthesised _ _

from butanol and ethylene oxide and propylene oxide, with an average molar mass M _n of 2250 g/mol, from Bayer Material Science, mono functional polyether amines (Jeffamine ^® M 1000, PO/EO molar ratio 3/19, and M 2070, PO/EO molar ratio 10/31, Huntsman Corp.). MPEG Carbowax ^® 2000, LB 25 or Jeffamine ^® M 2070 is preferably used as compound d). MPEG Carbowax ^® 2000 or LB 25 is particularly preferred.

Component d) is preferably present in amounts from 1 to 6 wt.%, particularly preferably 1.5 to 5 wt.%, relative to all structural components of the polyurethane polymer.

Suitable ionic or potentially ionic compounds d) are, for example, mono- and dihydroxycarboxylic acids, mono- and diaminocarboxylic acids and salts thereof such as dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, N-(2- aminoethyl)-B-alanine, malic acid, citric acid, glycolic acid, lactic acid, glycine, alanine, taurine, lysine, 3,5-diaminobenzoic acid, an addition product of IPDI and acrylic acid (EP-A 0 916 647, example 1) and the alkali and/or ammonium salts thereof- Preferred ionic or potential ionic compounds are those having carboxy or carboxylate groups and a functionality of 1.9 to 2.1. Particularly preferred ionic compounds have a hydroxy functionality of 1.9 to 2.1 and contain carboxylate groups as ionic or potentially ionic groups, such as the salts of dimethylol propionic acid or dimethylol butyric acid.

The polyamines e) used for chain extension preferably have a functionality of between 1 and 2 and are for example diamines or polyamines and hydrazides, for example ethyl ene di amine , 1 ,2- a n d 1 , 3-diaminopropane, 1 ,4-diaminobutane, 1,6-diaminohexane, isophorone diamine, mixtures of isomers of 2,2,4- and 2,4,4- trimethyl hexamethylene diamine, 2-methyl pentamethylene diamine, diethylene triamine, 1,3- and 1,4-xylylene diamine, a,a,a',a'-tetramethyl-l,3- and -1,4-xylylene diamine and 4,4-diaminodicyclohexylmethane, dimethylethylene diamine, hydrazine or adipic acid dihydrazide. - -

Compounds containing active hydrogen with varying reactivity to NCO groups can also be used in principle as component e), such as compounds which in addition to a primary amino group also have secondary amino groups or which in addition to an amino group (primary or secondary) also have OH groups. Examples thereof are primary/secondary amines such as 3-amino-l-methylaminopropane, 3-amino-l- e thy l ami no p ro p an e , 3-amino-l-cyclohexylaminopropane, 3-amino-l- methylaminobutane, also alkanol amines such as N-aminoethyl ethanolamine, ethanolamine, 3-aminopropanol or neopentanolamine.

Diethanolamine and/or hydrazine and/or isophorone diamine (IPDA) and/or ethylene diamine are preferred. Hydrazine and/or isophorone diamine and/or ethylene diamine are particularly preferred.

Component e) is preferably present in amounts from 0.2 to 2.5 wt.%, particularly preferably 0.3 to 2 wt.%, relative to all structural components of the polyurethane polymer. Neutralising amines f) which can optionally be used are in the case of anionic groups bases such as ammonia, ammonium carbonate or ammonium hydrogen carbonate, trimethylamine, triethylamine, tributylamine, diisopropyl ethylamine, dimethyl ethanolamine, diethyl ethanolamine, triethanolamine, alkali hydroxides or carbonates, preferably triethylamine, triethanolamine, dimethyl ethanolamine or diisopropyl ethylamine, most particularly preferably triethylamine. The amount of bases is between 30 and 100%, preferably between 40 and 90%, of the amount of anionic groups.

The low-molecular-weight polyols g) which can optionally be used to synthesise the polyurethane resins generally bring about a stiffening and/or a branching of the polymer chain. The molecular weight is preferably between 62 and 200 and their functionality is preferably 2 to 3. Suitable polyols c) can contain aliphatic, alicyclic or aromatic groups. The low-molecular-weight polyols having up to about 20 carbon atoms per molecule, such as for example ethylene glycol, diethylene glycol, triethylene glycol, 1 ,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butylene - -

glycol, cyclohexanediol, 1 ,4-cyclohexanedimethanol, 1,6-hexanediol, hydroquinone dihydroxyethyl ether, bisphenol A (2,2-bis(4-hydroxyphenyl)propane), hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane) and mixtures thereof, and trimethylolpropane, glycerol or pentaerythritol, can be cited here by way of example. Ester diols such as for example 5-hydroxybutyl-s-hydroxyhexanoic acid ester, ro-hydroxyhexyl-y-hydroxybutyric acid ester, adipic acid-( -hydroxyethyl) ester or terephthalic acid-bis( -hydroxyethyl) ester can also be used. Hexanediol and/or trimethylolpropane and/or butanediol are preferred. Trimethylolpropane and/or butanediol are particularly preferred. All methods known from the prior art can be used to produce the PU dispersions according to the invention, such as for example the prepolymer mixing method, acetone method or melt dispersion method. The PU dispersion is preferably produced by means of the acetone method.

To produce the PU dispersion by the acetone method, part or all of constituents b), c), d), optionally g) and the polyisocyanate component a) for producing an isocyanate-functional polyurethane prepolymer are conventionally prepared and optionally diluted with a solvent that is miscible with water but inert with regard to isocyanate groups, such as for example acetone or butanone, and the mixture thus obtained is heated to temperatures in the range from 50 to 120°C. The catalysts known in polyurethane chemistry can be used to accelerate the isocyanate addition reaction. Dibutyl tin dilaurate is preferred.

Suitable solvents are the conventional aliphatic, keto-functional solvents such as for example acetone, butanone, which can be added not only at the start of production but also optionally in portions later. Acetone or butanone is preferred. The constituents of a) to d) and optionally g) optionally not yet added at the start of the reaction are then incorporated. - -

In the production of the polyurethane prepolymer the substance ratio of isocyanate groups to isocyanate-reactive hydroxy groups n [NCO] / n [OH] is 1.0 to 3.5, preferably 1.1 to 3.0, particularly preferably 1.1 to 2.0.

The reaction of components a) to d) and optionally g) to form the prepolymer takes place partially or completely, but preferably completely. In this way polyurethane prepolymers containing free isocyanate groups are obtained in bulk or in solution.

In a further process step, if not already done or only partially done, the prepolymer obtained is then dissolved with the aid of aliphatic ketones such as acetone or butanone. Following complete dissolution, neutralisation of the potentially ionic compound d) with a neutralising amine f) is optionally performed for complete or partial salt formation from d).

Then the NH ₂ - and/or NH-functional components e) n [NH2] are reacted with the remaining isocyanate groups n [NCO] - n [OH]. This chain extension/termination can take place either in solvent before dispersion, during dispersion or in water after dispersion. Chain extension preferably takes place before dispersion in water. Preferably 5 - 80% of the remaining NCO groups are reacted with the polyamines e), more preferably 10 - 50%.

Preferably the total stoichiometry of the inventive polyurethane urea dispersions follows the following relation: n[NCO] (n[NH2]) ^

n[OH] n[NCO] - n[OH] '

If water or organic solvents are additionally used as diluting agents, the diluting agent content is preferably 70 to 95 wt.%.

Production of the polyurethane-urea dispersion according to the invention from the prepolymers takes place following chain extension. To this end the dissolved and chain-extended polyurethane polymer is either introduced into the dispersing water, optionally with intensive shearing, such as for example vigorous stirring, or - -

conversely the dispersing water is stirred into the prepolymer solutions. The water is preferably added to the dissolved prepolymer.

The solvent still contained in the dispersions after the dispersing step is conventionally then removed by distillation. Removal during the dispersion step itself is likewise possible.

The solids content of the polyurethane-polyurea dispersion according to the invention is between 20 and 70 wt.%, preferably between 25 and 60 wt.% and particularly preferably between 30 and 50 wt.%.

The invention also provides the use of the polyurethane-polyurea dispersions according to the invention for producing coating agents for wood, plastic, metal, glass, textiles, leather, paper and fibres such as for example glass fibres, plastic fibres and graphite fibres, preferably as an aqueous anchor coat for producing textile coatings. The dispersions according to the invention can be applied to all possible fabrics, such as woven fabrics, knitted fabrics, non-woven fabrics, filled nonwovens and stitched fabrics.

The aqueous coating agents containing the polyurethane-polyurea dispersions according to the invention can contain auxiliary substances and additives as a further component. These can be co-binders, thickeners, adhesion promoters, lubricants, wetting additives, dyes, light stabilisers, antioxidants, pigments, fillers, flow control agents, antistatics, UV absorbers, film-forming aids, defoamers, flame retardants, biocides, surface-active compounds or plasticisers as well as light stabilisers and antioxidants.

Suitable crosslinkers, such as for example polyisocyanates, blocked polyisocyanates, melamine crosslinkers, carbodiimides and polyaziridines, can also be included in the formulation.

The polyurethane-polyurea dispersions according to the invention can be used as a constituent in water-based paints for the coating of surfaces. To this end the polyurethane-polyurea dispersions according to the invention are mixed with further - -

components such as for example aqueous dispersions based on polyesters, polyurethanes, polyurethane-polyacrylates, polyacrylates, polyethers, polyester- polyacrylates, alkyd resins, polymers, polyamides/polyimides or polyepoxides.

The coating can be produced by the various spraying methods, such as for example compressed air, airless or electrostatic spraying methods, using one-component or optionally two-component spraying lines. The paints and coating agents containing the polyurethane-polyurea dispersions according to the invention can also be applied by other methods, however, such as for example by brushing, rolling, spraying, dipping, spattering, printing or knife application.

If the dispersions according to the invention are used in the coating of textile products, the methods known to the person skilled in the art can be used. These include inter alia direct coating, reverse coating, lamination and dry lamination. The coated textile is then advantageously cured at temperatures of 70 to 160°C, causing an anchor coat to form on the textile fabric. Curing takes place even more preferably in several, preferably three, temperature zones, at 70°C to 90°C (first temperature zone), 90°C to 110°C (second temperature zone) and 140°C to 160°C (third temperature zone).

- -

Examples:

Raw materials used:

Desmodur ^® 44 M Flakes = 4,4 ^* -MDI (CAS 101-68-8, Bayer Materials cience AG, DE) Desmodur ^® LS 2424 = mixture of 2,4'-MDI and 4,4'-MDI, approx. 1 : 1, Bayer MaterialScience AG, DE

Desmodur ^® XP 2410 = aliphatic polyisocyanate, Bayer MaterialScience AG, DE

Desmodur ^® 3100 = aliphatic polyisocyanate, Bayer MaterialScience AG, DE

Impranil ^® DLU = aliphatic polyurethane-urea dispersion, Bayer MaterialScience AG, DE

Impranil ^® DLC-F = aliphatic polyurethane-urea dispersion, Bayer MaterialScience AG, DE

Impranil ^® LP RSC 4002 = aromatic polyurethane-urea dispersion, Bayer MaterialScience AG, DE Borchigel ALA = polyacrylate-based thickener, Borchers, DE

Euderm White = coloured pigment, Bayer AG, DE

Byk 333 = flow control agent, BYK, DE

Ceraflor 920 = polymer-based matting agent, BYK, DE

Desmophen ^® LP 112 = polypropylene oxide diol with an average molar mass M _n of 1000 g/mol, (Bayer MaterialScience AG, DE)

Desmophen ^® LB 25 = mono functional polyether based on ethylene oxide/propylene oxide with an ethylene oxide content of 84%, M _n = 2250 g-mol ^"1 (Bayer MaterialScience AG, DE)

DMPA = dimethylol propionic acid (CAS 4767-03-7, Aldrich, DE) - -

IPDA = isophorone diamine (CAS 4767-03-7, Aldrich, DE) TEA = triethylamine (CAS 121-44-8, Aldrich, DE)

Methods used: The solids contents were determined in accordance with DIN EN ISO 3251.

Unless expressly indicated otherwise, NCO contents were determined volumetrically in accordance with DIN EN ISO 11909.

Particle size: The average particle size (APS) was determined by means of laser correlation spectroscopy (using a Malvern Zetasizer 1000, Malvern Instruments Ltd.); the z averages are given.

Production of dispersions:

Example 1

165 g of 4,4 ^* -MDI are added to 304.6 g of the polyether polyol LP 112, 27.0 g of the monofunctional hydrophilising agent LB25 and 16.1 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 3.76%) is reached. Then 911 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 12.1 g of TEA in 56.5 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 5.2 g of the chain extender IPDA in 18.7 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 1218 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 30.0%, a pH of 8.8 and an average particle size of 145 nm is formed. The dispersion proves to be stable in storage and forms no sediment when stored for four weeks at room temperature.

Example 2 - -

158.1 g of 4,4 ^* -MDI are added to 314.9 g of the polyether polyol LP 112, 25.9 g of the mono functional hydrophilising agent LB25 and 15.4 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 3.22%) is reached. Then 914 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 1 1.6 g of TEA in 54.1 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 1.1 g of the chain extender IPDA in 3.9 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 1226 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 30.0%, a pH of 8.8 and an average particle size of 120 nm is formed. The dispersion proves to be stable in storage and forms no sediment when stored for four weeks at room temperature.

Example 3 151.3 g of 4,4'-MDI are added to 323 g of the polyether polyol LP 1 12, 24.8 g of the monofunctional hydrophilising agent LB25 and 14.7 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 2.72%) is reached. Then 914 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 1 1.1 g of TEA in 51.8 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 4.8 g of the chain extender IPDA in 17.2 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 1219 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 31.0%, a pH of 8.8 and an average particle size of 110 nm is formed. The dispersion proves to be stable in storage and forms no sediment when stored for four weeks at room temperature.

Example 4 - -

140.9 g of 4,4 ^* -MDI are added to 342 g of the polyether polyol LP 112, 23.1 g of the mono functional hydrophilising agent LB25 and 13.7 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 1.84%) is reached. Then 924 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 10.4 g of TEA in 48.2 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 4.5 g of the chain extender IPDA in 16 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 1231 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 30.2%, a pH of 8.9 and an average particle size of 120 nm is formed. The dispersion proves to be stable in storage and forms no sediment when stored for four weeks at room temperature.

Example 5 (not according to the invention) 137.5 g of 4,4'-MDI are added to 253,8 g of the polyether polyol LP 1 12, 22,5 g of the mono functional hydrophilising agent LB25 and 13.4 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 3,76%o) is reached. Then 760 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 10.1 g of TEA in 47.1 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 6,5 g of the chain extender IPDA in 23,3 g of water are added and the mixture is stirred for 30 min. A dispersion with 630 g of water could not be performed as relatively large clumps formed at the stirrer following the addition of water. Example 6 (not according to the invention)

137.5 g of 4,4 ^* -MDI are added to 253,8 g of the polyether polyol LP 112, 22,5 g of the mono functional hydrophilising agent LB25 and 13.4 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 3,76%o) is reached. Then 760 g of acetone are added at 80°C, the mixture - -

is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 10.1 g of TEA in 47.1 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 9,8 g of the chain extender IPDA in 35 g of water are added and the mixture is stirred for 30 min. A dispersion with 630 g of water could not be performed as relatively large clumps formed at the stirrer following the addition of water.

Example 7

144,4 g of 4,4 ^* -MDI are added to 209,4 g of the polyether polyol LP 112, 18,6 g of the mono functional hydrophilising agent LB25 and 11,1 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 6,17%) is reached. Then 682 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 8,3 g of TEA in 38,8 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 6,4 g of the chain extender IPDA in 23 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 716 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 35.9%, a pH of 9,2 and an average particle size of 263 nm is formed. The dispersion proves to be stable in storage and forms no sediment when stored for four weeks at room temperature. Example 8 (not according to the invention)

168,4 g of 4,4 ^* -MDI are added to 203 g of the polyether polyol LP 112, 18 g of the mono functional hydrophilising agent LB25 and 10,7 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 8,11%) is reached. Then 711 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 8,1 g of TEA in 37,6 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 8,8 g of the chain extender IPDA in 31,6 g of water are added and the mixture is stirred for 30 min. A dispersion with 630 - -

g of water could not be performed as relatively large clumps formed at the stirrer following the addition of water.

Example 9 (not according to the invention)

92.8 g of Desmodur LS 2424 are added to 198.3 g of the polyether polyol LP 112, 15.2 g of the mono functional hydrophilising agent LB25 and 9.0 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 2.72%) is reached. Then 561 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 6.8 g of TEA in 31.8 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 2.9 g of the chain extender IPDA in 10.5 g of water are added and the mixture is stirred for 30 min. The product is dispersed in 748 g of water and then the acetone is removed by distillation under 120 mbar and at 40°C. An aqueous dispersion with a solids content of 29.9%, a pH of 8.5 and an average particle size of 350 nm is formed. The dispersion proves not to be stable in storage and forms a slight sediment when stored for four weeks at room temperature.

Example 10 (not according to the invention)

127.2 g of 4,4'-MDI are added to 276 g of the polyether polyol LP 112 and 21.4 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 2.82%) is reached. Then 740 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 9.4 g of TEA in 43.5 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 4 g of the chain extender IPDA in 14.4 g of water are added and the mixture is stirred for 30 min. A dispersion with 630 g of water could not be performed as relatively large clumps formed at the stirrer following the addition of water.

Example 11 (not according to the invention) - -

103.1 g of 4,4 ^* -MDI are added to 293.4 g of the polyether polyol LP 112 and 25.7 g of the mono functional hydrophilising agent LB25 at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 2.26%) is reached. Then 751 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 3.3 g of the chain extender IPDA in 11.7 g of water is added and the mixture is stirred for 30 min. The addition of 627 g of water led to irreversible thickening of the reaction batch and the experiment was stopped.

Example 12 (not according to the invention) 127.2 g of 4,4'-MDI are added to 276 g of the polyether polyol LP 112 and 21.4 g of DMPA at 70°C and the mixture is then reacted to form the prepolymer until the theoretical NCO value (NCO-1 = 2.82%) is reached. Then 740 g of acetone are added at 80°C, the mixture is cooled to 40°C and the prepolymer is dissolved. Following complete dissolution a solution of 9.4 g of TEA in 43.5 g of acetone is added for neutralisation purposes and the mixture is stirred for a further 15 min. Then 4 g of the chain extender IPDA in 14.4 g of water are added and the mixture is stirred for 30 min. A dispersion with 630 g of water could not be performed as relatively large clumps formed at the stirrer following the addition of water.

Example 13 (not according to the invention, procedure based on Macromol. Symp. 2004, 216, page 229-239)

The polypropylene oxide diol LP 112 was used in place of the polyester used in the text, consisting of adipic acid and ethylene glycol with a molar mass M _n of 1000 g/mol. The prepolymer produced in this process was not however completely soluble in acetone under reflux, and thick wall adhesions remained. This method does not appear to be suitable for use as an industrial process.

Table 1 : av. particle viscosity / storage example a b a-b

size / ran mPas stability** - -

It is obvious that only the inventive examples lead to polyurethane urea dispersions with satisfactorily properties.

Application examples 1-6:

The coating experiments on a textile substrate took place by means of the transfer method in an Isotex pilot plant using knife application. A polyester fabric was used as the substrate. Drying took place under hot air in a drying tunnel with three different temperature zones with ascending temperatures (80°C, 100°C, 150°C). - -

a) Finish

Table 1 shows the composition of the finish coats used to produce laminates 1 to 6:

Table 1, * according to the invention

Impranil DLC-F is placed in a container, Desmodur 3100 is added whilst stirring, and all further components are stirred in successively until a homogeneous formulation is produced. Borchigel ALA is stirred in to thicken the mixture to a brushing viscosity. Coating takes place at a travel rate of 2.0 m/min with a knife gap of 0.25 mm and at an application rate of 61 g/m ² . Drying takes place in three temperature zones of 80°C, 100°C and 150°C. - -

b) Undercoat

Table 2 shows the composition of the undercoats used to produce laminates 1 to 6:

Table 2, * according to the invention

To produce the undercoats Impranil DLU is placed in a container, then Euderm White and Bayhydur 3100 are added whilst stirring and the mixture is then thickened to brushing viscosity by the addition of Borchigel ALA. Coating takes place at a travel rate of 2.0 m/min with a knife gap of 0.20 mm and at an application rate of 90 g/m ² . Drying takes place in three temperature zones of 80°C, 100°C and 150°C.

- -

3) Anchor coat

Table 3 shows the composition of the anchor coats used to produce laminates 1 to 6:

Table 3, * according to the invention

To produce the anchor coats the polyurethane-urea dispersions are prepared and homogeneously mixed with the polyisocyanate XP 2410 whilst stirring. Then the mixture is thickened to brushing viscosity with Borchigel ALA. Coating takes place at a travel rate of 2.0 m/min with a knife gap of 0.12 mm (1 and 2) or 0.17 mm (3 to 6) and at an application rate of 55 g/m ² (1 and 2), 42 g/m ² (3 and 4) and 45 g/m ² (5* and 6*). Drying takes place in three temperature zones of 80°C, 100°C and 150°C. The dry adhesion of the laminates prepared in the manner described above is tested using a Zwick Z 1.0/THlS device. Testing is carried out on specimens measuring 200 mm x 15 mm at a tensile testing rate of 100 mm per minute. To this end a cotton strip provided with the coating is ironed evenly onto the test surface at a temperature of - -

180°C until bonding or melting can be detected. Before testing, the specimens are allowed to fully cure for at least 24 h. The results are set out in Table 4, the average of two measurements being given in each case:

The dispersions according to the invention can be seen to lead to a significantly higher dry adhesion.