EP0000029B1 - Process for the preparation of aqueous dispersions or solutions of polyurethanes, their use as coatings forf lexible substrates - Google Patents

Description

Processes for producing stable, aqueous polyurethane-polyurea dispersions are known (e.g. DT-PS 1 184946, DT-PS 1 178 586, DT-AS 1237306, DT-Osen 1 495 745, 1 595 602, 1 770 068, 2 019 324, see also D. Dieterich et al, Angew. Chem. 82, 53 (1970)). The dispersions described are based on the principle of incorporating hydrophilic centers in a macromolecular chain of a polyurethane-polyurea molecule. These hydrophilic centers or so-called internal emulsifiers are ionic groups or ether functions in the known dispersions. The ionic groups are either incorporated into the prepolymer in the form of special diols or used as modified amines for chain extension of the prepolymers, each of which has at least two terminal NCO functions.

High quality polyurethane films, e.g. The value level necessary for textile coating has so far been obtained from dispersions which are produced using organic solvents during polyaddition.

The polyaddition in solution makes it possible to build up a high molecular weight polyurethane in a homogeneous phase before it is dispersed in water. As a result, the solid of the disperse particles is also highly homogeneous.

This very well developed process, which includes both anionic, cationic and nonionic emulsifier segments, has the disadvantage that the organic solvent has to be distilled off and rectified in a complex process. This is associated with a poor space-time yield in the manufacturing process. The organic solvent as the reaction medium increases the risk of explosion and fire during the manufacturing process. When trying to manufacture such products without the use of organic solvents, at best, relatively coarse dispersions are obtained, the film-forming ability and mechanical properties of which are insufficient for a number of areas of application.

On the other hand, processes have also become known for the solvent-free production of polyurethane dispersions, such as e.g. the so-called melt dispersion method (DOS 1 770068, D. Dieterich and H. Reiff, Angew. makromol. Chem. 76, 85 (1972)). With this. The process converts an oligourethane containing terminal acylated amino groups and modified with ionic groups by means of formaldehyde into the corresponding terminal oligourethane containing methylol groups bound to acylated amino groups, which is then chain-extended by heat treatment with a condensation reaction of the terminal reactive methylol groups. This chain extension reaction can take place in the presence of water, so that an aqueous dispersion of a polyurethane is formed immediately. This process is particularly suitable for the production of cationically modified polyurethanes or for the production of polyurethanes containing anionic carboxylate groups. The required combination of the isocyanate polyaddition reaction with the chain extension reaction mentioned via polycondensation-capable methylol groups bonded to terminal acylamino groups represents a comparison to the known isocyanate polyaddition by the prepolymer process, in which prepolymers containing isocyanate groups with the classic chain extenders such as e.g. Water or diamines are implemented, increased effort. This effort could be justified in the process of DOS 1 770068 by the fact that it was possible for the first time to produce polyurethane dispersions without the aid of special stirrers and without the aid of emulsifiers and without the aid of solvents.

DT-OS 2 446 440 describes a further process which relates to the solvent-free production of polyurethanes in aqueous dispersion. A sulfonate and NCO group-containing prepolymer is then reacted without the use of solvents with a compound which is difunctional in the sense of the isocyanate polyaddition reaction and has hydrogen atoms which are reactive toward isocyanate groups.

In this process, the NCO prepolymer is reacted with the NCO group reactive compound during the dispersing process, i.e. after the previous solution of the chain extender in the dispersion water or after the dispersion of the prepolymer in water. The process mentioned enables the production of high-quality, sulfonate-containing polyurethanes in aqueous dispersion. However, it has the disadvantage that it is limited to polyurethanes bearing sulfonate groups and only water or water-soluble polyamines are used as chain extenders; can be.

Another characteristic of this process is that the chain extension. ie the structure of a high molecular weight polyurethane urea takes place in the heterogeneous phase. The chain extender - diamine, water - is in the liquid phase and only reaches the center of the dispersed particle over a certain period of time. It is obvious that the chain extender, ie the diamine dissolved in water, initially in the outer areas of the disper particle reacted. The concentration of the chain extender decreases steadily towards the center of the particle. Dispersions whose solid particles are not homogeneous are therefore obtained by this process. This results in polyurethane ureas which, compared to products made in homogeneous solution, have lower mechanical strength and, in some cases, poorer resistance to hydrolysis.

In addition, it is practically not possible to produce highly concentrated dispersions with a solids content of more than 40% by the process mentioned, since at higher solids concentrations the individual dispersed particles are linked to larger aggregates by the chain extender which is essentially between the particles. This leads to very high viscosities that are unsuitable for processing and even to pasting of the aqueous dispersions. Another disadvantage of the process described is that water-insoluble or poorly soluble polyamines cannot be used as chain extenders. Especially with such polyamines as e.g. with diamino-dicyclohexylmethane, however, polyurethaneureas with excellent mechanical properties can be produced.

The object of the present invention was therefore to provide a solvent-free or low-solvent process which allows the production of polyurethanes in the aqueous phase with improved properties, the improvement being achieved in particular by the high molecular weight solids distributed in the liquid aqueous medium should be obtained by polyaddition in the most homogeneous phase possible.

Surprisingly, it has now been found that high-quality polyurethanes can be produced in aqueous dispersion or solution by pre-dispersing NCO-containing prepolymers which contain a hydrophilic radical and / or an external emulsifier with a polyamine prior to dispersion in water. Chain extenders mixed in at least partially blocked form and then dispersed in water.

The reaction of organic polyisocyanates, in particular NCO prepolymers with blocked polyamines, in particular polyaldimines or polyketimines and water, is already known from GB-PS 1 064 841. According to the teaching of this prior publication, however, this implementation is used exclusively to solve a problem that is completely different from the object of the present invention. The problem underlying the prior publication was namely to produce a mixture which was stable in the absence of water and which, when water, in particular atmospheric humidity, was added, could be reacted to a high molecular weight plastic at any time. According to the teaching of this prior publication, the solution to this problem was to use mixtures of an NCO prepolymer and a blocked chain extender (polyaldimine or polyketimine) as such in the absence of water, mixtures which are stable in storage. Any suggestions as to how the known methods of the prior art for the production of aqueous polyurethane dispersions could be improved cannot be gathered from the aforementioned prior publication, since the water is used only in the amounts required for releasing the chain extender, and also there nowhere is the use of emulsifiers or of hydrophilic NCO prepolymers, as are generally used for the preparation of aqueous polyurethane dispersions, mentioned.

The present invention therefore relates to a process for the preparation of aqueous solutions or dispersions of polyurethane polyureas by reacting chemically incorporated hydrophilic groups and / or external prepolymers containing at least 2 free isocyanate groups and not containing chemically bound emulsifiers and having at least 2 primary and / or Organic compounds containing secondary amino groups in the aqueous phase, characterized in that the prepolymer containing hydrophilically modified and / or an isocyanate group containing an external emulsifier is mixed in the absence of water with compounds which contain at most one free primary or secondary amino group and at least one blocked, under which Influence of water a free primary or secondary amino group forming group and a total of at least two at least partially blocked primary and / or secondary amino groups, and then this mixture with What mixed up.

Finally, the present invention also relates to the use of the dispersions or solutions produced by this process for coating flexible substrates.

Starting materials for the process according to the invention are at least 2 terminal NCO prepolymers containing isocyanate groups. Difunctional NCO prepolymers are preferably used. The NCO prepolymers to be used in the process according to the invention are preferably those which have one or more hydrophilic groups (s) which are responsible for their solubility or dispersibility in water. However, it is also possible to use hydrophobic NCO prepolymers per se in the process according to the invention if their solubility or dispersibility in Water is taken care of by using external emulsifiers. Of course, it is also conceivable to increase the hydrophilicity of built-in hydrophilic group-containing NCO prepolymers by additionally using external emulsifiers.

These explanations already show that the exact chemical structure of the NCO prepolymers is not critical in the process according to the invention. This means, in particular, that all NCO prepolymers which have already been used in the preparation of aqueous polyurethane dispersions or solutions are suitable for carrying out the process according to the invention. They are produced using known methods of the prior art and are described, for example, in DT-OSen 1 495 745, 1 495 847, 2 446 440 2 340 512, US Pat. No. 3,479,310, GB Patents 1,153,088 or 1 076 688.

wobei Q für einen aliphatischen Kohlenwasserstoffrest mit 4 bis 12 Kohlenstoffatomen, einen cycloaliphatischen Kohlenwasserstoffrest mit 6 bis 15 Kohlenstoffatomen, einen aromatischen Kohlenwasserstoffrest mit 6 bis 15 Kohlenstoffatomen oder einen araliphatischen Kohlenwasserstoffrest mit 7 bis 15 Kohlenstoffatomen bedeutet. Beispiele derartiger bevorzugt einzusetzender Diisocyanate sind Hexamethylendiisocyanat, Isophorondiisocyanat, 4,4'-Diisocyanatodicyclohexylmethan, 2,4-Diisocyanatotoluol, 2,6-Diisocyanatotoluol, 4,4'-Diisocyanatodiphenylmethan, p-Xylylen-diisocyanat sowie aus diesen Verbindungen bestehende Gemische.The preparation of the NCO prepolymers with chemically incorporated hydrophilic groups, which are preferably used in the process according to the invention, is carried out in analogy to the methods as mentioned in the literature references mentioned by way of example. Starting materials for the production of these NCO prepolymers are accordingly
1. any organic polyisocyanates, preferably diisocyanates of the formula

wherein Q represents an aliphatic hydrocarbon group having 4 to 12 carbon atoms, a cycloaliphatic hydrocarbon group having 6 to 15 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms or an araliphatic hydrocarbon group having 7 to 15 carbon atoms. Examples of such preferred diisocyanates are hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, p-xylylene diisocyanate and mixtures consisting of these compounds.

It is of course also possible in the process according to the invention to use the polyisocyanates known per se in polyurethane chemistry or modified ones known per se, for example carbodiimide groups, allophanate groups, isocyanurate groups, urethane groups and / or biuret groups.

2. Any organic compounds with at least two groups that are reactive toward isocyanate groups, in particular a total of two amino groups, thiol groups, carboxyl groups and / or hydroxyl-containing organic compounds of the molecular weight range 62-10,000, preferably 1,000 to 6,000. The corresponding dihydroxy compounds are preferably used. The use of tri-functional or higher-functional compounds in the sense of the isocyanate polyaddition reaction in small proportions to achieve a certain degree of branching is possible, as is the possible use of tri- or higher-functional polyisocyanates already mentioned for the same purpose.

Hydroxyl compounds to be preferably used are the hydroxypolyesters, hydroxypolyethers, hydroxypolythioethers, hydroxypolyacetals, hydroxypolycarbonates and / or hydroxypolyesteramides known per se in polyurethane chemistry. The hydroxyl group-containing polyesters are e.g. Reaction products of polyhydric, preferably dihydric and optionally additionally trihydric alcohols with polyhydric, preferably dihydric, carboxylic acids. Instead of the free polycarboxylic acids, the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof can also be used to produce the polyesters. The polycarboxylic acids can be aliphatic, cycloaliphatic, aromatic and / or heterocyclic in nature.

Examples include: adipic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic acid, maleic anhydride. Polyhydric alcohol oils include, for example, ethylene glycol, propylene glycol, (1,2) and - (1,3), butylene glycol 1,4) and - (2,3), hexanediol- (1,6), bis-hydroxymethylcyclohexane), 2-methyl-1,3-propanediol, glycerin, trimethylolpropane, hexanetriol- (1,2,6), further Polyethylene glycols, polypropylene glycols, and polybutylene glycols in question. The polyesters may have a proportion of terminal carboxyl groups. Polyesters of lactones, for example _E- caprolactone or hydroxycarboxylic acids, for example ω-hydroxycaproic acid, can also be used.

The polyethers which are preferred according to the invention and preferably have two hydroxyl groups are those of the type known per se and are, for example, polymerized by themselves with epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin, for example in the presence of BF ₃ , or by adding these epoxides, optionally in a mixture or in succession, to starting components with reactive hydrogen atoms such as alcohols and amines, for example water, ethylene glycol, propylene glycol (1,3) or - (1,2), 4,4'-dihydroxy-diphenylpropane, Aniline.

Polyethers modified by vinyl polymers, such as those produced by polymerizing styrene or acrylonitrile in the presence of polyethers (American Pat. Nos. 3,383,351, 3,304,273, 3,523,093, 3,110,695), German Patent 1 152 536) are also suitable. The proportionally higher-functionality polyethers to be used, if appropriate, are formed in an analogous manner by alkoxylation of higher-functionality starter molecules known per se, for example ammonia, ethanolamine, ethylenediamine or sucrose.

Among the polythioethers, the condensation products of thiodiglycol with itself and / or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or amino alcohols should be mentioned in particular.

As polyacetals e.g. the compounds which can be prepared from glycols, such as diethylene glycol, and formaldehyde.

Suitable polycarbonates containing hydroxyl groups are those of the type known per se.

The polyester amides and polyamides include e.g. the predominantly linear condensates obtained from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated amino alcohols, diamines, polyamines and their mixtures. Polyhydroxyl compounds already containing urethane or urea groups can also be used.

Low molecular weight polyols can also be used, e.g. Ethanediol, 1,2-and 1,3-propanediol, 1,4-and 1,3-butanediol, pentanediols, hexanediols, trimethylolpropane, hexanetriols, glycerol and pentaerythritol.

Representatives of the polyisocyanate and hydroxyl compounds mentioned to be used in the process according to the invention are e.g. in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology", written by Saunders-Frisch, Interscience Publishers, New York, London, Volume I, 1962, pages 32-42 and pages 44-54 and Volume II, 1964, Pages 5-6 and 198-199, as well as in the plastics manual, volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

3. Chemically fixed hydrophilic groups, preferably in the sense of the isocyanate addition reaction, mono- and in particular difunctional structural components of the type described by way of example in the above-mentioned references with regard to the preparation of aqueous polyurethane dispersions or solutions, i.e. For example, diisocyanates, diamines or dihydroxy compounds or diisocyanates or glycols containing ionic or potential ionic groups or polyethylene oxide units. The preferred hydrophilically modified structural components include, in particular, the sulfonate group-containing aliphatic diols according to DT-OS 2 446 440, the cationic or also anionic built-in internal emulsifiers according to German patent application P 26 51 506.0 and also the monofunctional built-in polyether described in this patent application. In the preparation of the NCO prepolymers according to the principles of the prior art known per se, the reactants are generally used in such proportions that a ratio of isocyanate groups to hydrogen atoms reactive toward NCO, preferably from hydroxyl groups, of from 1.05 to 10, preferably from 1.1 to 3 correspond.

The order in which the individual reactants are added is largely arbitrary. You can either mix the hydroxyl compounds and add the polyisocyanate, or you can gradually add the mixture of hydroxyl compounds or the individual hydroxyl compounds to the polyisocyanate component.

The NCO prepolymers are preferably produced in the melt at 30-190 ° C., preferably at 50-120 ° C. The prepolymers could of course also be produced in the presence of organic solvents, although one of the main advantages of the process according to the invention can be seen in the fact that such solvents can be dispensed with. Suitable solvents, e.g. in an amount up to 25% by weight, based on the solid, could be used e.g. Acetone, methyl ethyl ketone, ethyl acetate, dimethylformamide or cyclohexanone.

• a) eine mittlere NCO-Funktionalität von 1,8 bis 2,2, vorzugsweise 2,
• b) einen Gehalt an kationischen oder anionischen eingebauten Gruppen von 0 bis 100, vorzugsweise 0,1 bis 100 und insbesondere 0,5 bis 50 Milli-Äquivalent pro 100 g Feststoff,
• c) einen Gehalt an seitenständig, endständig und/oder innerhalb der Hauptkette eingebauten, inner halb eines Polyäthersegments vorliegenden Äthylenoxid-Einheiten von 0 bis 30, vorzugsweise 0,5 bis 30 und insbesondere 1 bis 20 Gew.-%, bezogen auf das Gesamtgewicht des Präpolymeren und
• d) ein mittleres Molekulargewicht von 500 bis 10.000, vorzugsweise 800 bis 4.000 aufweisen.

The nature and proportions of the starting materials used in the preparation of the NCO prepolymers are preferably chosen so that the NCO prepolymers

• a) an average NCO functionality of 1.8 to 2.2, preferably 2,
• b) a content of cationic or anionic built-in groups of 0 to 100, preferably 0.1 to 100 and in particular 0.5 to 50 milliequivalents per 100 g of solid,
• c) a content of laterally, terminally and / or within the main chain, within a polyether segment present ethylene oxide units of 0 to 30, preferably 0.5 to 30 and in particular 1 to 20 wt .-%, based on the total weight of the Prepolymers and
• d) have an average molecular weight of 500 to 10,000, preferably 800 to 4,000.

As already stated, the preferred NCO prepolymers include those which are either ionic groups of the type mentioned under b), ie in particular -COO-, -S03 or = N ⁺ =, or nonionic groups of the type mentioned under c) or both have ionic as well as nonionic groups of the type mentioned. However, it is also possible to use NCO prepolymers in the process of the invention, in the production of which none of the hydrophilic structural components mentioned under 3 were used, in which the content of those mentioned under b) or c) above Groups is therefore 0. If such NCO prepolymers are used, which also have the properties mentioned under a) and d) above, the use of external emulsifiers is essential when carrying out the process according to the invention. Suitable emulsifiers of this type are described, for example, by R. Heusch in "Emulsions", Ullmann, Volume 10, pages 449-473, Weinheim 1975. Both ionic emulsifiers such as alkali and ammonium salts of long-chain fatty acids or long-chain aryl (alkyl) sulfonic acids are suitable, as well as non-ionic emulsifiers such as ethoxylated alkylbenzenes with an average molecular weight of 500 to 10,000.

These external emulsifiers are thoroughly mixed with the NCO prepolymers before the process according to the invention is carried out. They are generally used in amounts of 1 to 30, preferably 5 to 20% by weight, based on the weight of the NCO prepolymer. It is entirely possible, even when using hydrophilically modified NCO prepolymers, to increase their hydrophilicity by additionally using such external emulsifiers, although this is generally not necessary.

In addition to the NCO prepolymers, at least 2 organic compounds having primary and / or secondary amino groups are used in the process according to the invention. These compounds are preferably aliphatic or cycloaliphatic diamines with only primary and / or secondary amino groups. The term "aliphatic or cycloaliphatic diamine" here refers exclusively to the nature of the carbon atoms linked to the amino groups. In the context of the present invention, araliphatic diamines are also to be regarded as aliphatic diamines. Diprimary diamines are particularly preferably used, with particular preference being given to those diprimary diamines which have at least one cycloaliphatic ring in their molecule with in particular 6 ring carbon atoms, it being irrelevant whether the amino groups are linked directly to this cycloaliphatic ring or to an alkyl Substituents, especially methyl substituents of this aliphatic ring are linked. The diamines to be used in the process according to the invention generally have a molecular weight of 60-500, preferably 100-250. Examples of suitable polyamines to be used in the process according to the invention are ethylene diamine, trimethylene diamine, tetramethylene diamine, hexamethylene diamine, propylene diamine-1,2, the mixture of isomers of 2,2,4- and 2,4,4-trimethylhexamethylene diamine, 1,3- and 1,4-xylylenediamine , Bis (2-aminoethyl) amine and methyl bis (3-aminopropyl) amine.

Besonders bevorzugt ist:

The preferred diamines include, for example:

It is particularly preferred:

An essential characteristic of the process according to the invention is that the polyamines mentioned by way of example are not used as such, but in the form of at least partially blocked amines. In the context of the present invention, “blocked amino groups” are to be understood in particular as those primary or secondary amino groups which have been converted into the corresponding ketimine, aldimine or enamine group by reaction with an aldehyde or ketone. Such ketimine, aldimine or enamine groups are largely inert to isocyanate groups at room temperature in the absence of moisture (cf. for example DT-US 2 125 247, US-PS 3 420 800, US-PS 3 567 692 or DT-OS 1 520 139) and only react with the entry of water with the liberation of the corresponding amino group with isocyanate groups. In the process according to the invention, preference is given to using at least partially blocked polyamines containing at least partially blocked aldimine or ketimine groups obtained from the polyamines with primary amino groups mentioned by way of preference. When carrying out the process according to the invention, however, it is not necessary for all the amino groups to be reacted with a ketone or aldehyde and thus to be blocked be cated. It is only essential that at least 50%, preferably more than 85% of the amino groups present in the amine component are present in blocked form, and that the amines to be used in the process according to the invention are on average at most 1 mol free amino groups, preferably at most 0.15 mol free Have amino groups per mole of polyamine. Thus, in the case of the use of a triamine having a total of 3 primary and / or secondary amino groups, which is not preferred but conceivable, it is also necessary if 2 of the total of 3 amino groups are present in blocked form. In the case of the preferred use of the diamines mentioned by way of example, it is necessary according to the statements made, but in extreme cases it is already sufficient if one of the two amino groups is present in blocked form. The preparation of the at least partially blocked polyamines containing ketimine, aldimine or enamine groups is part of the known prior art and is described, for example, in Houben-Weyl, Methods of Organic Chemistry, Volume XI / 2, pages 73 ff. Or in DT-OS 2 125 247. Since the amino groups of the amine component to be used according to the invention need not be blocked quantitatively, it is also unnecessary to carry out the condensation reaction quantitatively in the production of the partially blocked polyamines.

For the preparation according to invention, at least partially blocked _'polyamines suitable aldehydes or ketones are any at least one ketone or aldehyde group and having, otherwise inert under the reaction conditions, organic compounds. However, aliphatic or cycloaliphatic aldehydes or ketones with a total of 2 to 18, or in the case of the cycloaliphatic compounds 5 to 18, preferably 3 to 6, or in the case of the cycloaliphatic compounds 5 to 6 carbon atoms are preferably used. Examples of suitable aldehydes or ketones are acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclohexanone or cyclopentanone. Aromatic aldehydes or ketones such as benzaldehyde, acetophenone or benzophenone are also suitable, but less preferred.

To carry out the process according to the invention, the NCO prepolymers which may contain external emulsifiers are mixed with the at least partially blocked polyamines mentioned. The quantitative ratio between NCO prepolymer and at least partially blocked polyamine is generally chosen so that the equivalent ratio (NCO groups of the prepolymer): (free + blocked amino groups of the amine component) is between 4: 1 and 1: 1, 5, preferably between 2: 1 and 1: 1.25 and in particular between 1.2: 1 and 1: 1.2. The two components are mixed in a temperature range from -20 to 100 ° C., preferably from 20 to 60 ° C. Since not all amino groups have to be blocked in the process according to the invention, when the two components are mixed, a reaction may occur between NCO groups and non-blocked amino groups, which can lead to a slight increase in viscosity. It is often advantageous to mix the NCO propolymer with the blocked polyamine just before it is dispersed in water.

The subsequent step of the process according to the invention consists in mixing the mixture with water to produce the aqueous dispersion with simultaneous hydrolysis of the blocked polyamine. So much water is used for this step that the dispersion has as high a solids content as possible. Dispersions with 40 to 70% solids can preferably be prepared very well. Further dilution with water is easily possible. The water is preferably added in one pour or gradually as desired. The mixing of the prepolymer with capped polyamine with water can also be carried out by introducing the mixture into the aqueous phase or by first mixing the prepolymer and capped polyamine and then water using a continuous process in suitable mixing units. Water from 0 to 90 ° C., preferably from 20 to 60 ° C., is used.

The resulting dispersions are very fine, the particles preferably have a size of 20-200 nm, can of course also be larger.

In a last step, the dispersions produced by the process according to the invention can of course be further modified in a known manner. You can e.g. add another water-soluble polyamine such as hydrazine after the dispersion, if the equivalent ratio of NCO to (blocked) amino groups has been selected so that free NCO groups are still present.

If the equivalent ratio of NCO groups to (blocked) amino groups has been selected in the range from 1: 1 to 1: 1.5, subsequent modification of the polyurethane provided with terminal amino groups is also possible in the aqueous phase. As modifiers, e.g. Mono- and polyisocyanates, which can also be present in capped form, and chemical compounds containing epoxy groups. The subsequent modification of the aqueous polyurethane ureas can achieve desired properties, such as a hydrophobization by reaction with stearyl isocyanate.

The question of whether the ver drive solutions or dispersions of the polyurethanes are obtained in water, is mainly dependent on the molecular weight and the hydrophilicity of the dissolved or dispersed particles, which in turn by suitable choice of type and ratio of the starting materials, especially in the preparation of the NCO prepolymers according to the known Principles of polyurethane chemistry can be set. For example, the use of an NCO prepolymer with a mean NCO functionality slightly below 2 leads to the polyaddition reaction being terminated before excessively high molecular weights are reached. The polyurethanes produced by the process according to the invention and present in aqueous dispersion or solution are on a par with the known polyurethanes produced in organic solvents. Films made from them have excellent mechanical strength and hydrolysis resistance and can be used for a wide variety of applications.

A particularly preferred area of use of the dispersions or solutions according to the invention is the coating of flexible substrates. The dispersions are particularly suitable for textile finishing, for glass fiber sizing or as adhesives.

example 1

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus Polyester und Bisulfit-Addukt gibt man bei 70°C das Isophorondiisocyanat und rührt bei 100°C, bis ein NCO-Wert von 5,3% erreicht ist. Dann kühlt man das Präpolymer auf 60°C ab, gibt das Bis-Ketimin zu und läßt in _'das gut gerührte Gemisch das Wasser einlaufen.

Execution:

• The isophorone diisocyanate is added to the mixture of polyester and bisulfite adduct dewatered at 120 ° C. in vacuo and the mixture is stirred at 100 ° C. until an NCO value of 5.3% is reached. It is then cooled, the prepolymer at 60 ° C., are the bis-ketimine added and allowed to _'the well-stirred mixture enter the water.

A dispersion is formed with a solids content of 40% and a Ford cup viscosity (4 mm nozzle) of 14 seconds. The dispersion shows a Tyndall effect in the translucent light.

The dispersion dries to clear, elastic films and is suitable for textile coating.

Example 2

A prepolymer according to Example 1 is produced. After cooling to 60 ° C., 250.2 g of a ketimine composed of isophoronediamine and methyl ethyl ketone (amino groups blocked to 87%) are stirred in and then dispersed as described in Example 1. The resulting dispersion is thin and shows a Tyndall effect.

Example 3

A prepolymer according to Example 1 is produced. After cooling to 60 ° C., 225 g of a ketimine composed of isophoronediamine and acetone (amino groups blocked to 80%) are stirred in and then dispersed as described in Example 1. The resulting dispersion is thin and shows a Tyndall effect.

Example 4

A prepolymer according to Example 1 is produced. After cooling to 60 ° C., 250.2 g of an aldimine composed of isophoronediamine and isobutyraldehyde (99% blocked amino groups) are stirred in and then dispersed as described in Example 1. The resulting dispersion is thin and shows a Tyndall. Effect.

Example 5

A prepolymer according to Example 1 is produced. After cooling to 60 ° C., 297 g of a ketimine composed of isophoronediamine and cyclohexanone (99% blocked amino groups) are stirred in and then dispersed as described in Example 1. The resulting dispersion is thin and shows a Tyndall effect.

Example 6

zu, worauf ein Temperaturanstieg um 10°C erfolgt. Die eingesetzte Menge an freien NH-Gruppen entspricht einem Umsatz von 5% der verfügbaren NCO-Gruppen. Anschließend werden 200,1 g eines Ketimins aus Isophorondiamin (Aminobruppen zu 90% blockiert) und Methyläthylketon eingerührt und man dispergiert wie in Beispiel 1 beschrieben. Die entstandene Dispersion ist dünnflüssig und zeigt einen Tyndall-Effect.A prepolymer according to Example 1 is produced. After cooling to 50 ° C., 25.3 g of a condensation product of diethylene triamine and methyl ethyl ketone of the formula are added

to, whereupon a temperature rise of 10 ° C occurs. The amount of free NH groups used corresponds to a conversion of 5% of the available NCO groups. 200.1 g of a ketimine composed of isophoronediamine (90% blocked amino groups) and methyl ethyl ketone are then stirred in and the mixture is dispersed as described in Example 1. The resulting dispersion is thin and shows a Tyndall effect.

Example 7

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus den beiden Polyestern und dem Bisulfit-Addukt gibt man bei 70°C das Hexamethylen-(1,6)-diisocyanat und rührt bei 100°C, bis ein NCO-Wert von 4,1% erreicht ist. Dann kühlt man das Präpolymer auf 80°C ab, gibt das Bis-Ketimin zu und läßt in das gut gerührte Gemisch das Wasser einlaufen.

Execution:

• The hexamethylene (1,6) diisocyanate is added to the mixture of the two polyesters and the bisulfite adduct, which has been dewatered in vacuo at 120 ° C., and stirred at 100 ° C. until an NCO value of 4. 1% is reached. Then the prepolymer is cooled to 80 ° C., the bis-ketimine is added and the water is run into the well-stirred mixture.

A dispersion with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 15 seconds is formed. The dispersion shows a Tyndall effect in the translucent light. The dispersion dries to clear, colorless, elastic films. It is suitable for coating paper and leather.

Example 8

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus den beiden Polyestern, dem Trimethylolpropan und dem Bisulfit-Addukt gibt man bei 70°C das Hexamethy!en(1,6)-diiso-- cyanat und rührt bei 100°C, bis ein NCO-Wert von 4,3% erreicht ist. Dann kühlt man das Präpolymer auf 80°C ab, gibt das Bis-Ketimin zu und läßt in das gut gerührte Gemisch das Wasser einlaufen.

Execution:

• To the mixture of the two polyesters, the trimethylolpropane and the bisulfite adduct, dewatered at 120 ° C in a vacuum, the hexamethylene (1,6) -diiso-- cyanate is added at 70 ° C and the mixture is stirred at 100 ° C until an NCO value of 4.3% has been reached. Then the prepolymer is cooled to 80 ° C., the bis-ketimine is added and the water is run into the well-stirred mixture.

A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 15 seconds. The dispersion shows a Tyndall effect in the translucent light. The dispersion is suitable as a binder in leather finishing. It dries to clear, colorless, elastic films.

Example 9

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus den beiden Polyestern und dem Bisulfit-Addukt gibt man bei 70°C das Hexamethylen(1,6)-diisocyanat und rührt bei 100°C, bis ein NCO-Wert von 3,4% erreicht ist. Man kühlt das Präpolymer auf 80°C ab, gibt das Bis-Ketimin zu und läßt dann in das gut gerührte Gemisch Wasser einlaufen.

Execution:

• The hexamethylene (1,6) diisocyanate is added to the mixture of the two polyesters and the bisulfite adduct, which has been dewatered in vacuo at 120 ° C., and stirred at 100 ° C. until an NCO value of 3.4 % is reached. The prepolymer is cooled to 80 ° C., the bis-ketimine is added and water is then run into the well-stirred mixture.

A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 13 seconds. The dispersion shows a Tydall effect in the translucent light.

Example 10

Durchführung:

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus dem Polyester und dem Poly- ätherdiol gibt man bei 70°C das Hexamethylen(1,6)-diisocyanat und rührt bei 100°C, bis ein NCO-Wert von 4,1% erreicht ist. Dann kühlt man das Präpolymer auf 40°C ab, gibt das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen.

Execution:

• The hexamethylene (1,6) diisocyanate is added to the mixture of the polyester and the polyetherdiol dewatered at 120 ° C. in vacuo and the mixture is stirred at 100 ° C. until an NCO value of 4.1% is reached. Then the prepolymer is cooled to 40 ° C., the bis-ketimine is added and water is run into the well-stirred mixture.

A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 17 seconds. The dispersion shows a strong Tyndall effect in the translucent light.

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus Polyester, Polyäther und Bisulfitaddukt gibt man bei 70°C das Isophorondiisocyanat und rührt bei 100°C, bis ein NCO-Wert von 4,0% erreicht ist. Dann kühlt man das Präpolymer auf 60°C ab, gibt das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen.

Execution:

• The isophorone diisocyanate is added to the mixture of polyester, polyether and bisulfite adduct dewatered at 120 ° C. in vacuo and the mixture is stirred at 100 ° C. until an NCO value of 4.0% is reached. Then the prepolymer is cooled to 60 ° C., the bis-ketimine is added and water is run into the well-stirred mixture.

• Zugfestigkeit: 494 kp/cm²
• Bruchdehnung: 580%

A dispersion is formed with a solids content of 60% and a Ford cup viscosity (4 mm nozzle) of 85 seconds. The dispersion shows a Tyndall effect in the translucent light. The dispersion is suitable for textile coating. It dries to clear, colorless, elastic films with the following properties:

• Tensile strength: 494 kp / cm ²
• Elongation at break: 580%

Example 11

Example 12

Execution:

A mixture of the isophorone diisocyanate and the hexamethylene (1,6) diisocyanate is added to the mixture of the polyester, the two polyethers and the bisulfite adduct, which has been dewatered in vacuo at 120 ° C., and stirred at 100 ° C., until an NCO value of 6.2% is reached. The prepolymer is cooled to 60 ° C., the bis-ketimine is added and water is then run into the well-stirred mixture. After 5 minutes, the hydrazine hydrate is added and stirring is continued for 2 hours. A dispersion is formed with a solids content of 40% and a Ford cup viscosity (4 mm nozzle) of 13 seconds. The dispersion shows a Tyndall effect in the translucent light. The dispersion is suitable for textile coating. It dries to a clear, colorless, elastic film, - which is characterized by hydrolysis resistance and resistance to UV radiation.

Example 13

Durchführung:

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus dem Polyester und dem Polyäther gibt man bei 70°C das Isophorondiisocyanat und rührt bei 100°C, bis ein NCO-Wert von 10,1% erreicht ist. Dann kühlt man wieder auf 70°C ab, rührt die Dimethylolpropionsäure ein und läßt das Präpolymer bei der gleichen Temperatur ausreagieren. Nach Erreichen des theoretischen NCO-Gehaltes von 4,7% gibt man nacheinander das Triäthylamin und das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen. Es entsteht eine Dispersion mit einem Feststoffgehalt von 30% und einer Fordbecherviskosität von 14 Sekunden. Die Dispersion zeigt im durchscheinenden Licht einen Tyndall-Effekt.

Execution:

• The isophorone diisocyanate is added to the mixture of polyester and polyether dewatered at 120 ° C. in vacuo and the mixture is stirred at 100 ° C. until an NCO value of 10.1% is reached. Then it is cooled again to 70 ° C., the dimethylolpropionic acid is stirred in and the prepolymer is allowed to react at the same temperature. After the theoretical NCO content of 4.7% has been reached, the triethylamine and the bis-ketimine are added in succession and water is run into the well-stirred mixture. A dispersion arises with a solids content of 30% and a Ford cup viscosity of 14 seconds. The dispersion shows a Tyndall effect in the translucent light.

Example 14

Durchführung:

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus dem Polyester und den beiden Polyäthern gibt man bei 70°C das Isophorondiisocyanat und rührt bei 100°C, bis ein NCO-Wert von 7,4% erreicht ist. Dann kühlt man weider auf 70% ab, rührt die Dimethylolpro- . pionsäure ein und läßt das Präpolymer bei der gleichen Temperatur ausreagieren. Nach Erreichen des theoretischen NCO-Gehaltes von 4,2% gibt man nacheinander das Triäthylamin und das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen. Es entsteht eine Dispersion mit einem Feststoffgehalt von 30% und einer Fordbecherviskosität (4 mm Düse) von 12 Sekunden. Die Dispersion zeigt im durchscheinenden Licht einen Tyndall-Effekt.

Execution:

• The isophorone diisocyanate is added to the mixture of the polyester and the two polyethers dewatered at 120 ° C. in vacuo and the mixture is stirred at 100 ° C. until an NCO value of 7.4% is reached. Then you cool down again to 70%, the dimethylolpro- is stirred. pionic acid and allows the prepolymer to react at the same temperature. After the theoretical NCO content of 4.2% has been reached, the triethylamine and the bis-ketimine are added in succession and water is run into the well-stirred mixture. A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 12 seconds. The dispersion shows a Tyndall effect in the translucent light.

Example 15

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus dem Polyester und dem Polyäther gibt man bei 60°C das Isophorondlisocyanat und tropft dann das N-Methyl-di- äthanolamin zu. Anschließend wird bei 100°C gerührt, bis ein NCO-Wert von 4,4% erreicht ist. Man kühlt das Präpolymer auf 60°C ab, gibt das Dimethylsulfat zu und rührt zur Vervollständigung der Quaternierungsreaktion 30 Minuten bei der gleichen Temperatur nach. Dann gibt man das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen.

Execution:

• The isophorone diisocyanate is added to the mixture of polyester and polyether dewatered in vacuo at 120 ° C. at 60 ° C. and the N-methyldiethanolamine is then added dropwise. The mixture is then stirred at 100 ° C until an NCO value of 4.4% is reached. The prepolymer is cooled to 60 ° C., the dimethyl sulfate is added and the mixture is stirred at the same temperature for 30 minutes to complete the quaternization reaction. Then the bis-ketimine is added and water is run into the well-stirred mixture.

A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 13 seconds. The dispersion shows a Tyndall effect in the translucent light.

Example 16

Durchführung:

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus dem Polyester und den beiden Polyäthern gibt man bei 60°C das Isophorondiisocyanat und tropft dann das N-Methyl-di- äthanolamin zu. Anschließend wird bei 100°C gerührt, bis ein NCO-Wert von 4,7% erreicht ist. Man kühlt das Präpolymer auf 60°C ab, gibt das Dimethylsulfat zu und rührt zur Vervollständigung der Quaternierungsreaktion 30 Minuten bei der gleichen Temperatur nach. Dann gibt man das Bis-Ketimin zu und läßt in das gut gerührte Gemisch Wasser einlaufen. Es entsteht eine Dispersion mit einem Feststoffgehalt von 30% und einer Fordbecherviskosität (4 mm Düse) von 16 Sekunden. Die Dispersion zeigt im durchscheinenden Licht einen Tyndall-Effekt..

Execution:

• The isophorone diisocyanate is added to the mixture of polyester and the two polyethers dewatered in vacuo at 120 ° C. at 60 ° C. and the N-methyl-diethanolamine is then added dropwise. The mixture is then stirred at 100 ° C until an NCO value of 4.7% is reached. The prepolymer is cooled to 60 ° C., the dimethyl sulfate is added and the mixture is stirred at the same temperature for 30 minutes to complete the quaternization reaction. Then the bis-ketimine is added and water is run into the well-stirred mixture. A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 16 seconds. The dispersion shows a Tyndall effect in the translucent light.

Example 17

Durchführung:

• Zu dem bei 120°C im Vakuum entwässerten Gemisch aus Polyester, Polyäther und Bisulfitaddukt gibt man bei 70°C das Hexa- ' methylen(1,6)-diisocyanat und rührt bei 100°C, bis ein NCO-Wert von 4,8% erreicht ist. Dann kühlt man das Präpolymer auf 40°C ab und gibt das Bis-Ketimin zu. Das homogene Gemisch wird anschließend unter gutem Rühren in das vorgelegte entionisierte Wasser eingegossen.

Execution:

• To the mixture of polyester, polyether and bisulfite adduct dewatered at 120 ° C. in a vacuum, the hexamethylene (1,6) diisocyanate is added at 70 ° C. and the mixture is stirred at 100 ° C. until an NCO value of 4.8 % is reached. Then the prepolymer is cooled to 40 ° C. and the bis-ketimine is added. The homogeneous mixture is then poured into the deionized water provided with thorough stirring.

A dispersion is formed with a solids content of 30% and a Ford cup viscosity (4 mm nozzle) of 14 seconds. The dispersion shows a Tyndall effect in the translucent light.

Claims (3)

1. Process for the preparation of aqueous solutions or dispersions of polyurethane poly- ureas by the reaction of prepolymers which have at least two free isocyanate groups and contain chemically fixed hydrophilic groups and/or external emulsifiers which are not chemically fixed, with organic compounds containing at least two primary and/or secondary amino groups, in the aqueous phase, characterised in that the prepolymer containing isocyanate groups, which prepolymer is hydro- philically modified and/or contains an external emulsifier, is mixed, in the absence of water, with compounds which have at the most one free primary or secondary amino group and at least one blocked group from which a free primary or secondary amino group is formed by the action of water, and a total of at least two at least partially blocked primary and/or secondary amino groups, and the mixture obtained is subsequently admixed with water.

2. Process according to claim 1, characterised in that the nature and proportions of the reactants are chosen so that from 0.25 to 1.5 at least partially blocked amino groups which are reactive with isocyanate groups are present for each isocyanate group of the prepolymer containing isocyanate groups.

3. The use of the dispersions or solutions obtained according to claims 1 and 2 for coating flexible substrates.