EP0000568B1 - Process for the preparation of aqueous dispersions or solutions of isocyanate polyaddition products; use of these dispersions or solutions in the preparation of coatings and films - Google Patents

Description

The present invention relates to a new process for the production of aqueous dispersions or solutions of isocyanate polyaddition products, and to their use for the production of coatings and coatings.

Processes for the preparation of stable, aqueous polyurethane-polyurea dispersions are known (for example DE-C 1 184 946, DE-C 1 178 586, DE-B 1 237 306, DE-A 1 495 745, DE-A 1 595 602 , DE-A 1 770 068, DE-A 2 019 324, DE-A 2 314 512, 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. In the known dispersions, these hydrophilic centers or so-called internal emulsifiers are polyether segments which have ionic groups or ethylene oxide groups. These hydrophilic centers 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.

Various processes can be used to prepare the dispersions known hitherto, e.g. in D. Dieterich and H. Reiff, Angew. macromol. Chemistry 26, 85 (1972). In general, either the solution of a polyurethane in an organic solvent is converted into an aqueous dispersion or a prepolymer stage with or without solvent is dispersed in water in liquid form. For example, a liquid prepolymer ionomer containing NCO groups can be introduced into water with vigorous stirring, initially creating an emulsion of the prepolymer which, by chain extension, reacts further with, for example, a di- or polyamine dissolved in water to give the high molecular weight polyurethane urea. Because of the hydrophilicity of the NCO prepolymer and its resulting good compatibility with water, an undesired reaction of isocyanate groups with water always occurs in different orders of magnitude, which leads to an uncontrolled molecular structure.

The present invention now presents a new principle for the production of aqueous dispersions or solutions of isocyanate polyaddition products, in which such side reactions are largely excluded. The new principle according to the invention is that hydrophilic, i.e. water-soluble or dispersible urethane prepolymers with terminal amino or semicarbazide groups in the aqueous phase with a hydrophobic chain extender, preferably a hydrophobic diisocyanate, extended, due to the hydrophobicity of the isocyanate hardly a side reaction with the water forming the continuous phase.

• a) ein durchschnittliches Molekulargewicht von weniger als 15 000 aufweisen,
• b) 0-120 Milliäquivalente pro 100 g Feststoff an eingebauten ionischen Gruppen und/oder 0-25 Gew.-% an eingebauten, innerhalb einer Polyätherkette vorliegenden Äthylenoxideinheiten -CHZ-CHZ-0- und/oder 0-30 Gew.-% an externen, nicht chemisch fixierten Emulgatoren aufweisen, wobei die Gesamtmenge der genannten hydrophilen Gruppen bzw. Hilfsmittel in einer die Dispergierbarkeit bzw. Löslichkeit der Oligourethane in Wasser gewährleistenden Menge vorliegt,
• c) endständige primäre oder sekundäre aminische Aminogruppen oder endständige Semicarbazidgruppen mit mindestens einer endständigen -NH-Gruppierung aufweisen;

in wäßriger Phase mit einem mindestens difunktionellen mit den endständigen Amino- bzw. Semicarbazidgruppen im Sinne einer Additionsreaktion oder Kondensationsreaktion reagierenden Kettenverlängerungsmittel unter Kettenverlängerung der Oligourethane zur Reaktion bringt.The present invention thus relates to a process for the preparation of aqueous dispersions or solutions of isocyanate polyaddition products, characterized in that oligourethanes which

• a) have an average molecular weight of less than 15,000,
• b) 0-120 milliequivalents per 100 g of solid of built-in ionic groups and / or 0-25% by weight of built-in ethylene oxide units -CHZ-CHZ-0 and / or 0-30% by weight present within a polyether chain have external, not chemically fixed emulsifiers, the total amount of said hydrophilic groups or auxiliaries being present in an amount ensuring the dispersibility or solubility of the oligourethanes in water,
• c) have terminal primary or secondary amino amino groups or terminal semicarbazide groups with at least one terminal -NH group;

in the aqueous phase with a chain extender which reacts at least difunctionally with the terminal amino or semicarbazide groups in the sense of an addition reaction or condensation reaction with chain extension of the oligourethanes.

The present invention also relates to the use of the dispersions or solutions obtainable by this process for the production of coatings and coatings.

• a) ein mittleres Molekulargewicht von weniger als 15 000, vorzugsweise von 1000-10 000,
• b) einen Gesamtgehalt an die Dispergierbarkeit bzw. Löslichkeit in Wasser gewährleistenden Gruppen und/oder Emulgator, d.h. einen Gehalt an kationischen bzw. anionischen eingebauten Gruppen von 0 bis 120, vorzugsweise 0,5 bis 50 Milliäquivalenten pro 100 g Feststoff und/oder einen Gehalt an seitenständig, endständig und/oder innerhalb der Hauptkette eingebauten, innerhalb eines Polyäthersegmentes vorliegenden Äthylenoxid-Einheiten -CH_2-CH_2-0- von 0-25, vorzugsweise 3 bis 18 Gew.-%, bezogen auf das Gesamtgewicht des Oligourethans und/oder einen Gehalt von 0 bis 30, vorzugsweise 5 bis 20, Gew.-%, bezogen auf das Gesamtgewicht des Oligourethans an externen, chemisch nicht eingebauten Emulgatoren,
• c) endständige primäre bzw. sekundäre Aminogruppen oder endständige Semicarbazidgruppen mit mindestens einer endständigen -NH-Gruppe, wie sie durch Umsetzung von Isocyanatgruppen mit mindestens 2 -NH-Gruppen aufweisenden Hydrazinen entstehen.

The oligourethanes to be used in the process according to the invention are characterized by

• a) an average molecular weight of less than 15,000, preferably 1000-10,000,
• b) a total content of the dispersibility or solubility in water-ensuring groups and / or emulsifier, ie a content of cationic or anionic built-in groups of 0 to 120, preferably 0.5 to 50 milliequivalents per 100 g of solid and / or a content of ethylene oxide units -CH _2- CH _2- 0-, incorporated laterally, terminally and / or within the main chain and present within a polyether segment, of 0-25, preferably 3 to 18% by weight, based on the total weight of the oligourethane and / or a content of 0 to 30, preferably 5 to 20,% by weight, based on the total weight of the oligourethane, of external, chemically unincorporated emulsifiers,
• c) terminal primary or secondary amino groups or terminal semicarbazide groups with at least one terminal -NH group, as are formed by reacting isocyanate groups with at least 2 -NH groups having hydrazines.

The molecular weight of the oligourethanes is essential here. It should preferably be between 1000 and 10000 are. In principle, prepolymers with average molecular weights between 10,000 and 15,000 can also be dispersed, although considerable difficulties arise. The molecular weight of the oligourethane can be adjusted in a simple and known manner by the type and proportions of the structural components. For example, by using an excess of NCO in the preparation of the NCO prepolymers, it is prevented that high molecular weight polyurethanes build up in the isocyanate polyaddition reaction.

The average molecular weight can be calculated as follows from the stoichiometry of the reaction.

If, for example, 2 mol of a dihydroxy compound of molecular weight 2000, 1 mol of a basic chain extender of molecular weight 119, 4.75 mol of diisocyanate (molecular weight hydrazine 32) are converted into an oligourethane with 2 terminal semicarbazide groups, the molecular weight is calculated

To ensure the dispersibility or solubility of the oligourethanes, the hydrophilic groups mentioned are preferably incorporated into the oligourethane. In contrast, the use of external emulsifiers is less preferred.

The oligourethanes to be used in the process according to the invention are prepared via the intermediate stage of the corresponding prepolymers containing terminal isocyanate groups, which otherwise correspond to the statements made above with regard to their molecular weight and with regard to their content of hydrophilic groups, since the terminal isocyanate groups are converted into terminal semicarbazide or Amino groups no significant increase in molecular weight occurs. This means that if oligourethanes with ionic groups or with nonionic hydrophilic groups of the type mentioned are used, these are already present in the NCO prepolymers used as intermediates for the preparation of the starting materials according to the invention, with the only exception that when using ionically modified oligourethanes when The inventive method is also conceivable that a potential ionic groups, ie in particular NCO prepolymer containing carboxyl or sulfonic acid groups is produced, the potential ionic groups of which are only converted into ionic groups, in particular by neutralization, after the NCO prepolymers have been converted into terminal amino groups or oligourethanes containing semicarbazide groups.

Oligourethanes are preferably used in the process according to the invention which have a terminal average of 1.8-2.2, preferably 2, amino or semicarbazide groups.

It is evident from the above statements that difunctional NCO prepolymers are preferably used to prepare the oligourethanes to be used according to the invention.

These are preferably those which have one or more hydrophilic groups which determine their solubility or dispersibility in water. According to the statements made above, it is also possible to use inherently hydrophobic NCO prepolymers if, before or after their conversion into terminal amino groups or semicarbazide groups, oligourethanes for their solubility or dispersibility in water are 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 or oligourethanes produced from them by additionally using external emulsifiers.

As far as the chemical nature of the NCO prepolymers corresponds to the above statements, their exact chemical structure is not critical. This means, in particular, that in principle all NCO prepolymers which have been used to date in the production of aqueous polyurethane dispersions or solutions are suitable. They are produced by known methods of the prior art and are described, for example, in DE-A 1 495 745, 1 495 847, 2 446 440, 2 340 512, US-A 3 479 310, 3 756 992, GB-A 1 158088 or 1 076 688.

• 1. beliebige organische Polyisocyanate, vorzugsweise Diisocyanate der Formel
  
  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 Tetramethylendiisocyanat, Hexamethylendiisocyanat, Dodecamethylendiisocyanat, 1,4-Diisocyanatocyclohexan, 1-lsocyanato-3,3,5-trimethylisocyanatomethylcyclohexan, isophorondiisocyanat, 4,4'-Diisocyanatodicyclohexylmethan, 4,4'-Diisocyanatodicyc)ohexyipropan-(2,2), 1,4-Diisocyanatobenzo), 2,4-Diisocyanatotoluol, 2,6-Diisocyanatotoluol, 4,4'-Diisocyanatodiphenylmethan, 4,4'-Diisocyanatodiphenylpropan-(2,2), p-Xylylen-diisocyanat oder a,a,a',a'-Tetramethyl-m- oder p-xylylen-diisocyanat, sowie aus diesen Verbindungen bestehende Gemische.

The preparation of the preferred NCO prepolymers with chemically incorporated hydrophilic groups 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
  
  where Q is 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 Means 7 to 15 carbon atoms. Examples of such preferred diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethylisocyanatomethylcyclohexane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, 4,4'-diisocyanate, 4,4'-diisocyanate , 2), 1,4-diisocyanatobenzo), 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 4,4'-diisocyanatodiphenylpropane- (2,2), p-xylylene diisocyanate or a , a, a ', a'-tetramethyl-m- or p-xylylene diisocyanate, and mixtures consisting of these compounds.

It is of course also possible to use the polyisocyanates known per se in polyurethane chemistry, or else modified polyisocyanates (for example) containing carbodiimide groups, allophanate groups, isocyanurate groups, urethane groups and / or biuret groups.

2. Any organic compounds with at least two groups which are reactive towards isocyanate groups, in particular a total of two amino groups, thiol groups, carboxyl groups and / or hydroxyl groups, having 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 refusal is possible, as is the possible use of tri- or higher-functional polyisocyanates already mentioned for the same purpose.

• Bernsteinsäure, Adipinsäure, Korksäure, Azelainsäure, Sebacinsäure, Phthalsäure, Isophthalsäure, Trimellitsäure, Phthalsäureanhydrid, Tetrahydrophthalsäureanhydrid, Hexahydrophthalsäureanhydrid, Tetrachlorphthalsäureanhydrid, Endomethylentetrahydrophthalsäureanhydrid, Glütarsäureanhydrid, Maleinsäure, Maleinsäureanhydrid, Fumarsäure, dimere und trimere Fettsäuren wie Ölsäure, gegebenenfalls in Mischung mit monomeren Fettsäuren, Terephthalsäuredimethylester, Terephthalsäurebis-glykolester. Als mehrwertige Alkohole kommen z.B. Äthylenglykol, Propylenglykol-(1,2) und -(1,3), mit Butylenglykol-(1,4) und -(2,3), Hexandiol-(1,6), Octandiol-(1,8), Neopentylglykol-Cyclohexandimethanol-(1,4-bis-hydroxymethylcyclohexan), 2-Methyl-1,3-propandiol, Glycerin, Trimethylolpropan, Hexantriol-(1,2,6), Butantriol-(1,2,4), Trimethyloläthan, Pentaerythrit, Chinit, Mannit und Sorbit, Methylglykosid, ferner Diäthylenglykol, Triäthylenglykol, Tetraäthylenglykol, Polyäthylenglykole, Dipropylenglykol, Polypropylenglykole, Dibutylenglykol und Polybutylenglykole in Frage. Die Polyester können anteilig endständige Carboxylgruppen aufweisen. Auch Polyester aus Lactonen, z.B. _E-Caprolacton oder Hydroxycarbonsäuren, z.B. w-Hydroxycapronsäure, sind einsetzbar.

Hydroxyl compounds which are preferably used are the hydroxypolyesters, hydroxypolyethers, hydroxypolythioethers, hydroxypolyacetals, hydroxypolycarbonates and / or hydroxypolyesteramides known per se in polyurethane chemistry. The hydroxyl group-containing polyesters are, for example, 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 anhydrides or corresponding polycarboxylic 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 and optionally substituted, for example by halogen atoms, and / or unsaturated. Examples include:

• Succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, Glütarsäureanhydrid, maleic acid, maleic anhydride, fumaric acid, dimeric and trimeric fatty acids such as oleic acid, optionally mixed with monomeric fatty acids, terephthalic acid dimethyl ester, Terephthalic acid bis-glycol ester. Examples of polyhydric alcohols include ethylene glycol, propylene glycol (1,2) and - (1,3), with butylene glycol- (1,4) and - (2,3), hexanediol- (1,6), octanediol- (1 , 8), neopentylglycol-cyclohexanedimethanol- (1,4-bis-hydroxymethylcyclohexane), 2-methyl-1,3-propanediol, glycerin, trimethylolpropane, hexanetriol- (1,2,6), butanetriol- (1,2,4 ), Trimethylolethane, pentaerythritol, quinite, mannitol and sorbitol, methylglycoside, also diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycols. The polyesters may have a proportion of terminal carboxyl groups. Polyesters of lactones, for example _E- caprolactone or hydroxycarboxylic acids, for example w-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 with themselves, for example in the presence of BF ₃ , by polymerization of epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin prepared by anal storage of these epoxides, optionally in a mixture or successively on starting components with reactive hydrogen atoms such as alcohols and amines, for example water, ethylene glycol, (1,3) or - (1,2), 4,4'-dihydroxydiphenylpropane, aniline .

Polyethers modified by vinyl polymers, e.g. by polymerization of styrene or acrylonitrile in the presence of polyethers (American patents 3383351, 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 known alkoxylation of higher-functionality starter molecules, e.g. Ammonia, ethanolamine, ethylenediamine or sucrose.

Among polythioethers, the condensation products of thiodiglycol with themselves and / or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or amino alcohols should be mentioned in particular. Depending on the co-components, the products are polythio ether, polythio ether ester, polythio ether ester amide.

As polyacetals e.g. the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-diethoxy-diphenyldimethylmethane, hexanediol and formaldehyde. Polyacetals suitable according to the invention can also be prepared by polymerizing cyclic acetals.

Suitable polycarbonates containing hydroxyl groups are those of the type known per se, for example by reacting diols such as propanediol (1,3), butanediol (1,4) and / or Hexanediol (1,6), diethylene glycol, triethylene glycol, tetraethylene glycol with diaryl carbonates, for example diphenyl carbonate or phosgene, can be prepared.

The polyester amides and polyamides include e.g. the predominantly lienear condensates obtained from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated amino alcohols, diamines, polyamides 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 or diamines such as e.g. Hexamethylenediamine or 1-amino-3,3,5-trimethyl-5-amino-cyclohexane.

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 urea manual, volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

If oligourethanes which have chemically fixed ionic or nonionic hydrophilic groups are used in the process according to the invention, they are prepared via the appropriately modified NCO prepolymers. These hydrophilically modified prepolymers are produced by known processes of the prior art, for example in accordance with DE-ASen 1 495 745, 1 495847, 2 446 440, 2 340 512, US-A 3 479 310, 3756992, GB-A 1 158 088 or 1 076 688 methods described. This means that in the preparation of the prepolymers, in addition to the starting materials already mentioned by way of example, chemically fixed hydrophilic groups, preferably in the sense of the isocyanate addition reaction, having mono- and in particular difunctional structural components of those exemplified in the abovementioned. Literature related 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 can also be used.

The preferred hydrophilically modified structural components include, in particular, the sulfonate group-containing aliphatic diols according to DE ― A 2 446 440, the cationic or also anionic internal emulsifiers according to DE-A 26 51 506 and also the monofunctional integrable polyethers described in this patent application.

wobei

• A und B für gleiche oder verschiedene zweiwertige aliphatische Kohlenwasserstoffreste mit 1 bis 6 Kohlenstoffatomen stehen,
• R für Wasserstoff, einen aliphatischen Kohlenwasserstoffrest mit 1 bis 4 Kohlenstoffatomen oder einen Phenylrest steht,
• X^* für ein Alkalimetallkation oder eine gegebenenfalls substituierte Ammoniumgruppe steht,
• n und m für gleiche oder verschiedene Zahlen von 0 bis 30 stehen,
• o und p für jeweils 0 oder 1 stehen und
• q für eine ganze Zahl von 0 bis 2 steht.

The preferred (potential) ionic structural components include, in particular, N-alkyldialkanolamines, such as, for example, N-methyldiethanolamine, N-ethyldiethanolamine or N-propyldipropanolamine, diaminosulfonates of the type described in CA-A 928 323, such as, for example, the sodium salt of N- (2-aminoethyl) - 2-aminoethanesulfonic acid, dimethylolpropionic acid and sulfonate diols of the general formula

in which

• A and B represent identical or different divalent aliphatic hydrocarbon radicals having 1 to 6 carbon atoms,
• R represents hydrogen, an aliphatic hydrocarbon radical having 1 to 4 carbon atoms or a phenyl radical,
• X ^{* represents} an alkali metal cation or an optionally substituted ammonium group,
• n and m represent the same or different numbers from 0 to 30,
• o and p each represent 0 or 1 and
• q represents an integer from 0 to 2.

The conversion of the potential ionic groups, which may have been initially incorporated into the polyaddition product, into ionic groups is carried out in a manner known per se by neutralizing the potential anionic and cationic groups, by quaternizing tertiary, aminic nitrogen atoms or of tertiary phosphinic phosphorus atoms which are present in the polyaddition products according to the invention can, if instead of the exemplified tertiary amines with hydrogen atoms reactive towards isocyanate groups, these tertiary amines analogous tertiary phosphines have been incorporated, or by converting any thioether groups present into the corresponding sulfonium salts with quaternizing agents. Suitable neutralizing and quaternizing agents are described in US Pat. No. 3,479,310, column 6. The conversion of the potential ionic groups into ionic groups can take place both before the conversion of the NCO prepolymers into the starting materials according to the invention and afterwards. In particular when carboxyl or sulfonic acid groups are present as potential ionic groups, neutralization of these groups after conversion of the NCO prepolymers into the oligourethanes to be used as starting material is conceivable.

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 2.5.

The order in which the individual reactants are added is largely arbitrary. You can either mix the hydroxy 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 to 190 ° C., preferably at 50 to 120 ° C. The prepolymers could of course also be produced in the presence of organic solvents.

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.

• Gemäß einer ersten Methode werden die NCO-Präpolymeren mit Hydrazinen der nachstehend beispielhaft genannten Art oder mit Diaminen zur Reaktion gebracht, deren Aminogruppen sich bezüglich ihrer Reaktivität gegenüber Isocyanatgruppen stark unterscheiden.

To prepare the oligourethanes to be used as starting materials in the process according to the invention, the NCO prepolymers mentioned by way of example are preferably modified by one of the following two methods:

• According to a first method, the NCO prepolymers are reacted with hydrazines of the type exemplified below or with diamines whose amino groups differ greatly in their reactivity towards isocyanate groups.

Suitable hydrazines are any hydrazines which have 2-NH groups, ie both hydrazine or hydrazine hydrate itself and any mono- or N, N'-disubstituted hydrazines. C _{1 -C 4} -alkyl radicals are particularly _suitable as substituents for the hydrazines. Accordingly, examples of suitable hydrazines are hydrazine, hydrazine hydrate, N-methylhydrazine, N, N'-dimethylhydrazine, N-butylhydrazine or N, N'-dibutylhydrazine.

Suitable diamines with amino groups of different reactivity are any diamines having primary and / or secondary amino groups corresponding to these conditions. The different reactivity of the amino groups of the diamines can be caused by steric and / or mesomeric effects and / or by different types of binding of the amino groups. The first-mentioned type of suitable diamines included 2,4-diaminotoluene, 1-methyl-2,4-diamino-cyclohexane or 2,4'-diaminodiphenylmethane. Diamines with amino groups of different reactivity, in which this different reactivity is due to a different type of binding of the amino groups, or in which steric effects can also play a role, are e.g. 2- (2-aminoethyl) aniline, 2- (3-aminopropyl) aniline, N- (3-aminopropyl) aniline, N- (6-aminohexyl) aniline, 2- (2-aminoethyl) naphthalene, N- (2-aminoethyl) aniline, 2- (2-aminoethylamino) naphthalene, 2-aminophenyl- (3-aminopropyl) thioether or 2-aminomethylaniline.

Simple aromatic diamines such as, for example, 1,4-diaminobenzene are also suitable, since the second amino group, owing to mesomeric effects after the first amino group has reacted, is less ready to react to isocyanate groups. In general, diamines are suitable whose pKb values for the two amino groups in an aqueous medium at 25 ° C. differ by at least a factor of 10 ³ , preferably by a factor of 10 ⁶ .

In general, the diamines or hydrazines have a molecular weight of 32 to 400.

The reaction of the NCO prepolymers with the hydrazines or diamines is generally carried out in the melt or in the presence of inert solvents of the type already mentioned by way of example at 10 to 120 ° C., the reactants being used preferably in amounts such that for every mole of NCO -Groups of the NCO prepolymer 0.8-1.2, preferably 1 mol of the hydrazine or diamine is omitted.

Solvents containing keto groups, such as e.g. Acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone are suitable.

wobei

• R, und R₂ für gleiche oder verschiedene Reste stehen und Wasserstoff, aliphatische Kohlenwasserstoffreste mit 1-4 Kohlenstoffatomen, cycloaliphatische Kohlenwasserstoffreste mit 5-7 Kohlenstoffatomen oder aromatische Kohlenwasserstoffreste mit 6-10 Kohlenstoffatomen bedeuten bzw. zusammen mit dem Ring-Kohlenstoffatom gemeinsam einen 5- oder 6-gliedrigen cycloaliphatischen Kohlenwasserstoff-Ring bilden können,
• X für einen Rest der Formel
  
  steht, wobei R₃ und R₄ für gleiche oder verschiedene Reste stehen und C,-C₄ Alkylreste, vorzugsweise jedoch Wasserstoff bedeuten und m 2 oder 3 bedeuten,
• Y für einen Rest der Formel
  
  steht, in welcher R₃ und R₄ die bereits genannte Bedeutung haben und n für eine ganze Zahl von 2 bis 6 steht.

According to a further method of converting the NCO prepolymers into starting materials suitable according to the invention, the NCO prepolymers are reacted with compounds which have a group which is reactive toward isocyanate groups, preferably a hydroxyl group, and also a blocked amino group which is inert towards isocyanate groups and which, under the influence of water forms a free amino group. Suitable such compounds are in particular those of the formula

in which

• R and R _{2 represent} identical or different radicals and represent hydrogen, aliphatic hydrocarbon radicals with 1-4 carbon atoms, cycloaliphatic hydrocarbon radicals with 5-7 carbon atoms or aromatic hydrocarbon radicals with 6-10 carbon atoms or together with the ring carbon atom together represent a 5- or can form 6-membered cycloaliphatic hydrocarbon ring,
• X for a residue of the formula
  
  where R ₃ and R _{4 are the} same or different radicals and are C, -C ₄ alkyl radicals, but preferably hydrogen and m are 2 or 3,
• Y for a residue of the formula
  
  stands in which R ₃ and R _{4 have} the meaning already mentioned and n stands for an integer from 2 to 6.

The N-hydroxyalkyl-oxazolidines are prepared by methods known from the literature, a ketone or an aldehyde being condensed with a bis- (hydroxyalkyl) amine with cyclizing dehydration and the water of reaction usually being removed azeotropically by an inert entrainer or by the excess carbonyl compound becomes.

eignen sich insbesondere nachstehend aufgeführte Aldehyde und Ketone:

• Formaldehyd, Acetaldehyd, Propionaldehyd, Butyraldehyd, Isobutyraldehyd, Benzaldehyd, Tetrahydrobenzaldehyd, Aceton, Methyläthylketon, Methylpropylketon, Methylisopropylketon, Diäthylketon, Methylbutylketon, Methylisobutylketon, Methyl-t-butylketon, Diisobutylketon, Cyclopentanon und Cyclohexanon Bevorzugt einzusetzende Carbonylverbindungen sind entsprechend der vorstehenden Definiton der bevorzugten Reste R₂ und R₃ Formaldehyd sowie die genannten aliphatischen Aldehyde bzw. Ketone.

As carbonyl compounds

Aldehydes and ketones listed below are particularly suitable:

• Formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, benzaldehyde, tetrahydrobenzaldehyde, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, diethyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl t-butyl ketone, cyclosefinonone ketone, cyclosefinonyl butyl, and cyclodefinonyl ketone are preferred, corresponding to the preferred R ₂ and R ₃ formaldehyde and the aliphatic aldehydes or ketones mentioned.

eignen sich besonders Bis-(2-hydroxyäthyl)-amin und Bis-(2-hydroxypropyl)-amin. Im Prinzip ebenso geeignet sind jedoch auch beispielsweise Bis-(2-hydroxybutyl)-amin, Bis-(2-hydroxyhexyl)-amin, Bis-(3-hydroxyhexyl)-amin, oder N-(2-hydroxypropyl)-N-(6-hydroxyhexyl)-amin.As bis (hydroxyalkyl) amines

Bis- (2-hydroxyethyl) amine and bis- (2-hydroxypropyl) amine are particularly suitable. In principle, however, bis- (2-hydroxybutyl) amine, bis (2-hydroxyhexyl) amine, bis (3-hydroxyhexyl) amine, or N- (2-hydroxypropyl) -N- ( 6-hydroxyhexyl) amine.

To convert the NCO prepolymers into the starting materials to be used according to the invention by this method, the hydroxyalkyloxazolidines are reacted with the NCO prepolymers at 20 to 120 ° C. in the presence or in the absence of solvents, the quantitative ratios of the reactants being chosen so that for each Mol isocyanate groups of the NCO prepolymer in the reaction mixture 0.8-1.2, preferably 1 mol of the oxazolidine derivative is present.

Another conceivable but less preferred method of converting the NCO prepolymers into starting materials suitable according to the invention consists in reacting the NCO prepolymers with a large excess of any organic diamine, for example with ethylenediamine or hexamethylenediamine, and then removing the unreacted excess. for example by vacuum distillation. By using a large excess, as with the first two methods mentioned, it is ensured that a significant molecular enlargement by chain extension does not occur. The use of continuously running, high-speed machines would be an advantage.

To carry out the process according to the invention, the modified NCO prepolymer with terminal semicarbazide groups, amino groups or oxazolidine groups is dispersed or dissolved in water, and when compounds containing oxazolidine groups are used, hydrolysis occurs immediately, releasing the corresponding amino groups from the oxazolidine residue. The amount of water in this dispersing or dissolving process is generally such that the weight ratio of prepolymer to water is between 65:35 and 5:95, preferably 55:45 and 20:80.

The temperature of the dispersing process should be above the softening point of the prepolymer, to the extent that above the softening point that stirring of the melt is ensured. In the case of purely non-ionic dispersions or solutions, the dispersion temperature should not be substantially above 60 ° C.

If necessary, the dispersing process can also be supported by adding external emulsifiers. If appropriate, these external emulsifiers are already added to the NCO prepolymers or to the starting materials to be used according to the invention and prepared from them. If at all, they are generally used in amounts of 1 to 30, preferably 5 to 20,% by weight, based on the NCO prepolymer or oligourethane. 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 e.g. Alkali and ammonium salts of long chain fatty acids or long chain aryl (alkyl) sulfonic acids, as well as nonionic emulsifiers such as e.g. ethoxylated alkylphenols with an average molecular weight of 400 to 10,000.

The actual process according to the invention now consists in chain extension of the oligourethanes present in aqueous solution or dispersion with suitable chain extenders.

Suitable chain extenders are any, preferably difunctional organic compounds which react largely selectively with the amino or semicarbazide groups of the oligourethane in the presence of water with these groups in the sense of an addition reaction or a condensation reaction. Suitable chain extenders are accordingly hydrophobic bis-epoxides such as the reaction products of bisphenol A with 2 moles of epichlorohydrin or higher molecular weight bis-epoxides with a maximum molecular weight of 3000 and in particular hydrophobic diisocyanates of the formula Q (NCO) _{2 of} the type already mentioned above as examples.

Particularly preferred chain extenders are hexamethylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane or any mixture of these diisocyanates. Also preferably difunctional NCO prepolymers with a maximum molecular weight of 3000, as can be obtained in a manner known per se by reacting the exemplified low molecular weight diisocyanates with suitable dihydroxy compounds, are suitable according to the invention as chain extenders.

In the chain extension reaction according to the invention, the chain extenders are generally used in amounts such that 0.4 to 1.0 mol, preferably 0.5 mol, of the difunctional chain extender are available for each mole of amino groups or semicarbazide groups of the oligourethane. The chain extension reaction according to the invention is generally carried out by stirring the chain extension agent, dissolved in an inert solvent, into the dispersion or solution provided. Liquid chain extenders without solvents are preferably used. The chain extension reaction according to the invention generally takes place in the temperature range from 0 to 100, preferably 10 to 70 ° C. In principle, it is also possible to use masked di- or polyisocyanates which, if appropriate, only have a prolonging or crosslinking effect after the dispersion has been applied during heating by splitting off the masking agent.

The dispersions or solutions accessible according to the invention are suitable for the known fields of application of the aqueous polyurethane dispersions. They can e.g. for leather finishing or wool finishing or can be used to coat a wide variety of materials, such as Textiles, plastics, glass, metals, paper or wood are used. can be used as paints or adhesives. Other uses include e.g. in the fields of glass fiber sizing or dispersing aids. These products can also be used as additives for plastic dispersions or as binders for e.g. Cork or wood flour, glass fibers, asbestos, paper-like materials, plastic or rubber waste and ceramic materials.

The dispersions or solutions according to the invention can be provided with any additives before their application. These include in particular crosslinking agents such as Formaldehyde, formaldehyde releasing compounds or melamine resins; Polymer latices of various origins, e.g. those based on polyacrylonitrile, butadiene-acrylonitrile copolymers or else based on grafted copolymers based on acrylonitrile, butadiene and styrene, and those based on poly (meth) acrylates. Aftertreatment of the dispersions or solutions according to the invention in accordance with the process of DE-A 27 08 442 is also possible.

Approach: Example 1 Approach:

Execution:

The polyester (PE) and the adduct (AD) are dewatered at 110 ° C. in a water jet vacuum with stirring for 45 minutes, cooled to 80 ° C. and reacted with the diisocyanate (H) at 80 ° C. After about 40 minutes, an NCO value of 2.75% is reached. The melt is cooled to 45 to 50 ° C. and stirred with hydrazine hydrate until no more isocyanate is found. With rapid stirring, the melt is dispersed with water at 50 ° C.

A finely divided dispersion with a Ford cup viscosity (4 mm nozzle) of 21 seconds at 29.8% solids is obtained. The average molecular weight of the oligourethane is 3080. The solid contains 1.9% SO ₃ ^⊖ groups. IPDI is stirred into the semicarbazide-terminal dispersion at room temperature. After stirring for 5 to 10 minutes, no isocyanate is found. There is a finely divided dispersion with a pH of 6.3, which dries out on heating to form non-tacky films.

The tensile strength of the film is 14.7 MPa with an elongation at break of 340%.

Example 2 Approach:

Execution:

The polyester (PE) and the adduct (AD) are dewatered at 110 ° C. with stirring in a water jet vacuum. It is cooled to 80 ° C. and butanediol is stirred in. After 10 _- minutes of stirring, the diisocyanate (H) is added and stirred at 80 ° C until an NCO-value of 5% is reached (about 30 minutes). The IPDA in acetone is then added and the mixture is stirred at 80 ° C. for 30 minutes. An NCO value of 3.0% is found. The melt is then stirred with the oxazolidine at 80 ° C. until no more isocyanate is found (about 1 hour). The small amount of acetone is removed in vacuo. The mixture is then dispersed at 80 ° C. with vigorous stirring with water.

The extremely finely divided dispersion has a Ford cup viscosity (4 mm nozzle) of 18 seconds with a solid of 28.75%. The average molecular weight of the oligourethane is 2350. The solid contains 21.5 milliequivalents per 100 g (1.72%) of SO _. ^9- groups.

16.3 g of isophorone diisocyanate are initially added to 600 g of the dispersion at room temperature and the mixture is stirred at this temperature for 1 hour. No more NCO groups are found. The dispersion is finely divided and shows a Tyndall effect in the translucent light. Their Ford cup viscosity (4 mm nozzle) with a solids content of 29.8% is 20 seconds. The pH is 7.1. The films from this dispersion are transparent and hard and are suitable for leather finishing.

Approach: Example 3 Approach:

Execution:

The polyester (PE) and the adduct (AD) are dewatered at 110 ° C. with stirring in a water jet vacuum. It is cooled to 80 ° C. and butanediol is stirred in. After stirring for 10 minutes, the diisocyanate (H) is added and the mixture is stirred at 80 ° C. until an NCO value of 2.8% is reached (about 2 hours). Then the NPDA is added at 60 ° C. and the mixture is stirred at 60 ° C. until the melt is free of NCO (approx. 30 minutes). The solid is dissolved very well with water at 60 ° C. to give a finely divided dispersion which, with a solid of 30.4%, has a Ford cup viscosity (4 mm nozzle) of 12 seconds. The average molecular weight of the solid is 3280. The solid contains 23.6 milliequivalents per 100 g (1.89%) of SO ₃ ^⊖ groups.

The amine-terminated oligourethane dispersion is stirred at room temperature with 38.6 g IPDI for 2 hours. Another 30.5 g of IPDI are then added in order to coat the dispersion particles with a urea shell in accordance with DE-A 2708442. The dispersion is then baked at 80 ° C. for 1 hour.

The Ford cup viscosity (4 mm nozzle) of the dispersion with a solids content of 32.5% is 12.7 seconds. The dispersion is centrifuge stable (3600 rpm for 15 minutes without sedimentation) and has a Tyndall effect in the translucent light. The pH is 5.4.

The films from this dispersion become clear and transparent; they do not stick, but have a pleasantly dry grip. The dispersion is suitable for coating textiles.

The tensile strength of the film is 23.1 MPa with an elongation at break of 916%.

Example 4 Approach:

Implementation: (see example 3)

A finely divided amine-terminal dispersion is obtained which has a Tyndall effect in the translucent light. The Ford cup viscosity (4 mm nozzle) for a solid of 30% is 38 seconds. The average molecular weight of the solid is 3320. The solid contains 23.4 milliequivalents per 100 g (1.87%) of SO ₃ ^⊖ groups.

Example 4a

In 607 g of the above 30% dispersion, 9.6 g of an 80:20 mixture of the 2,4- or. Added 2,6-diisocyanatotoluenes and stirred for 10 minutes. For further isocyanate modification analogous to DE-A 27 08 442, a further 9.6 g of the above isocyanate mixture are added at 25 ° C. and stirred until no more isocyanate is found, the temperature towards the end of the reaction (after approx. 3 Hours) is increased to 90 ° C.

A sediment-stable dispersion is obtained which shows a Tyndall effect in the translucent light. With a solid of 32.8%, the dispersion has a Ford cup viscosity (4 mm nozzle) of 12.7 seconds. Your pH is 4.5. The film from this dispersion is very hard and does not stick.

Example 4b

18.4 g of a bis-epoxide (started on bisphenol A, MW 338) dissolved in 50 g of acetone are added to 601 g of the dispersion from Example 4 at room temperature. The mixture is then heated to 80 ° C. and stirred at this temperature for 4 hours. The small amount of acetone is drawn off in a water jet vacuum. A centrifuge-stable dispersion (15 minutes, 3500 rpm) with a Ford cup run-out time (4 mm nozzle) of 14.4 seconds with a solids content of 39.5% is obtained. The pH is 4.5. When the dispersion is applied, a largely tack-free film is formed which can be used as an adhesive coating on a wide variety of materials such as Textile or leather can be used.

Example 4c

11.4 g of melted, warm 4,4'-diisocyanatodiphenylmethane are added to 500 g of the dispersion from Example 4, and the mixture is slowly heated to 80 ° C. with stirring. At this temperature, stirring is continued for 4 hours. The dispersion is free of isocyanates.

A finely divided dispersion is obtained which has a Tyndall effect in the translucent light. The dispersion has a pH of 7.5. The Ford cup run-out time (4 mm nozzle) is 35.3 seconds with a solids content of 35.3%.

The film from the dispersion is tack-free and hard.

Example 5 Approach:

Execution:

Compare Example 4; but instead of the o-aniline aminoethyl thioether, a mixture of hydrazine hydrate and acetone is added, which was previously stirred for about 1 hour on a magnetic stirrer. After 15 minutes, the NCO-free melt is dispersed with water. The acetone is then stripped off in a water jet vacuum at approx. 30-35 ° C. The semicarbazide-terminated oligourethane dispersion is implemented in two stages with IPDI. In the first stage, the semicarbazide is reacted with 38.6 g IPDI at 25 ° C, in the second stage the dispersion is modified with IPDI analogously to DE-A 2708442, the IPDI being added at 25 ° C and 3 hours at 25 -30 ^o C is stirred.

Then the dispersion is baked out at 80 ° C.

A finely divided dispersion with a Tyndall effect in translucent light is obtained, which has a Ford cup viscosity (4 mm nozzle) of 11.5 seconds at a solids content of 31.4%. The pH is 5.4. The films do not stick and have a pleasant dry grip.

Claims (3)

1. Process for the preparation of aqueous dispersions or solutions of isocyanate polyaddition products, characterised in that oligourethanes which

a) have an average molecular weight of less than 15,000,

b) contain from 0-120 milliequivalents, per 100 g of solid content of built-in ionic groups and/or from 0 to 25% by weight of built-in ethylene oxide units ―CH₂―CH₂―O- present within a polyether chain and/or from 0-30% by weight of external emulsifiers which are not chemically fixed, the total quantity of the above mentioned hydrophilic groups or auxiliary agents being sufficient to ensure the dispersibility or solubility of the oligourethanes in water, and

c) contain primary or secondary aminic amino end groups or semicarbazide end groups with at least one NH group in the end position

are reacted in the aqueous phase with a chain lengthening agent which is at least difunctional and which undergoes an addition reaction or condensation reaction with the amino or semicarbazide end groups to effect chain lengthening of the oligourethans.

2. Process according to Claim 1, characterised in that the chain lengthening agents used are hydrophobic diisocyanates.

3. Use of the dispersions or solutions prepared according to Claims 1 and 2 for the production of films and coatings.