EP0000347A1 - Aqueous solutions of polyurethane ionomers with electrolytic stability and process for the preparation of these ionomers. - Google Patents

Abstract

Electrolyte-stable aqueous solutions of polyurethane ionomers having an essentially linear molecular structure and containing both hydrophilic polyalkylene oxide/polyether chains and ionic groups, and a process for the preparation of the novel compounds by reacting diisocyanates with the conventional components used for the synthesis of polyurethanes containing groups which are reactive to isocyanate groups, in the presence of components which contain nonionic hydrophilic groups and components which contain ionic groups or groups which can be converted into ionic groups.

Description

Aqueous solutions of polyurethanes or polyurethane ureas have been known for a long time (see, for example, Angewandte Chemie, 82, (197 ₀ ) pages 53 to 55, there ref. Cit. 4-8, 10a).

The hydrophilic centers built into the known water-soluble polyurethanes or polyurethane ureas can be both salt-like, i.e. represent ionic groups as well as hydrophilic nonionic groups.

The former "polyurethane ionomers" include both chemically fixed cations, i.e. in particular chemically incorporated polyurethanes containing ammonium ions as well as chemically fixed anions, i.e. in particular chemically incorporated polyurethanes containing sulfonate or carboxylate groups. The latter non-ionic, water-soluble polyurethanes or polyurethane ureas in particular include chains of polyethylene oxide.

The solutions of these polyurethanes have different, characteristic properties depending on the type of the hydrophilic center. So are polyurethane ionomer solutions because the the salt groups contained in them are practically not temperature-dependent in their solubility, stable against heating to boiling, non-ionic solutions, on the other hand, coagulate when heated (at approx. 60 ° C), since the polyethylene oxide chains gradually lose their solubility in water at higher temperatures. In contrast to ionomers, these solutions are resistant to the addition of practically unlimited amounts of electrolytes and are stable even after freezing and thawing.

The sensitivity to electrolytes is particularly high in solutions of cationic polyurethanes, but solutions of polyurethane polycarboxylates are also sensitive. Small amounts of aqueous electrolyte solutions cause turbidity, larger amounts lead to slimy or cheesy deposits. Even if flocculation does not occur, the colloidal chemical state changes, which is noticeable, for example, in the changed viscosity and rheology.

In many cases, this electrolyte instability is extremely disadvantageous and makes it difficult or even inhibits the practical use of the products. For example, For the use of polyurethane ionomer solutions for the production of pigment pastes, for the surface coating of inorganic substrates such as fillers and fibers, as a dyeing aid a certain resistance to electrolytes is required.

The present invention now provides new water-soluble polyurethanes, which are in the form their aqueous solution have both the advantage of excellent frost and electrolyte resistance and the advantage of very good temperature resistance. As has surprisingly been found, it is possible to produce such water-soluble polyurethanes if both hydrophilic segments containing ethylene oxide units and ionic groups are incorporated into the polyurethane. This is quite surprising since it turned out that mixtures of aqueous solutions of ionic and nonionic polyurethanes in no way have such a combination of desirable properties. Rather, such mixtures primarily have the disadvantages of the individual components.

oder COO^G-Gruppen aufweisen, gegenüber der Einwirkung von Elektrolyten erzielt. Selbst bei hohem Gehalt an kationischen Zentren, z.B. mehr als 20 Milliäquivalenten pro 100 g Polyurethan an

werden die Lösungen durch verdünnte Natriumchloridlösung nicht mehr gefällt.The incorporation of hydrophilic polyether segments, either within the polymer main chain or at its ends or in the form of side chains, provides surprisingly effective protection for polyurethanes

or have COO ^G groups, achieved with respect to the action of electrolytes. Even with a high content of cationic centers, for example more than 20 milliequivalents per 100 g of polyurethane

the solutions are no longer precipitated by dilute sodium chloride solution.

• a) hydrophile Polyalkylenoxid-Polyätherketten mit einem Gehalt an Äthylenoxid-Einheiten von 2 bis 50 Gew.-%, bezogen auf das gesamte Polyurethan und
• b) einen Gehalt an =N^⊕=,
  
  oder -COO e Gruppen von 16 bis 250 Milliäquivalenten pro 100 g.

The present invention thus relates to electrolyte-stable aqueous solutions of polyurethane ionomers with an essentially linear molecular structure, characterized by

• a) hydrophilic polyalkylene oxide polyether chains with a content of ethylene oxide units of 2 to 50 wt .-%, based on the entire polyurethane and
• b) a content of = N ^⊕ =,
  
  or -COO e groups of 16 to 250 milliequivalents per 100 g.

• a) Mono- oder Diisocyanate und/oder im Sinne der Isocyanatpolyadditionsreaktion mono- oder difunktionelle Verbindungen mit gegenüber Isocyantgruppen reaktionsfähigen Wasserstoffatomen mit Äthylenoxid-Einheiten aufweisenden hydrophilen Ketten als auch
• b) Mono- oder Diisocyanate und/oder im Sinne der IsocyanatPolyadditionsreaktion mono- oder difunktionelle Verbindungen mit gegenüber Isocyanatgruppen reaktionsfähigen Wasserstoffatomen mit ionischen Gruppen oder in ionische Gruppen überführbaren Gruppen

mitverwendet werden, wobei die Art und Menge bzw. Neutralisierungs- oder Quaternierungsgrad der Komponenten a) und b) so bemessen wird, daß im letztlich erhaltenen Polyurethan 2 bis 50 Gew.-% an Äthylenoxid-Einheiten und 16 bis 250 Milliäquivalent pro 100 g an ionischen Gruppen vorliegen.The present invention finally also relates to the preferred process for the preparation of the water-soluble polyurethanes according to the invention with an essentially linear molecular structure by reacting organic diisocyanates with organic compounds of the molecular weight range 300 to 6000 having difunctional terminal hydrogen atoms that are reactive toward isocyanate groups, with the use of the solubility of the polyurethane-guaranteeing structural components with hydrophilic groups or groups which can be converted into such hydrophilic groups, the at least partial conversion of the latter groups into hydrophilic groups taking place during or after the polyaddition reaction, and optionally also using the chain extenders known per se in polyurethane chemistry less than 300 molecular weight and optionally also with the use of in Auxiliaries and additives customary in polyurethane chemistry, characterized in that both as structural components with hydrophilic groups or with groups which can be converted into hydrophilic groups

• a) mono- or diisocyanates and / or in the sense of the isocyanate polyaddition reaction mono- or difunctional compounds with reactive towards isocyanate groups Hydrogen atoms with hydrophilic chains containing ethylene oxide units as well
• b) mono- or diisocyanates and / or in the sense of the isocyanate polyaddition reaction, mono- or difunctional compounds having hydrogen atoms which are reactive toward isocyanate groups and having ionic groups or groups which can be converted into ionic groups

are used, the type and amount or degree of neutralization or degree of quaternization of components a) and b) being such that in the ultimately obtained polyurethane 2 to 50% by weight of ethylene oxide units and 16 to 250 milliequivalents per 100 g ionic groups.

Organic diisocyanates suitable for the preferred process mentioned above for the preparation of the polyurethane elastomers according to the invention are those of the general formula R (NCO) _{2 '} where R is an organic radical, as is preferred by removing the isocyanate groups from an organic diisocyanate of the molecular weight range 112-1000 140-400. Particularly preferred diisocyanates suitable for the process according to the invention are those of the general formula given, in which R represents a divalent aliphatic hydrocarbon radical having 4-18 carbon atoms, a divalent cycloaliphatic hydrocarbon radical having 5-15 carbon atoms, a divalent aromatic hydrocarbon radical having 6-15 carbon atoms or one araliphatic hydrocarbon radical having 7-15 carbon atoms. Typical representatives of organic diisocyanates which are preferably suitable for the process according to the invention are, for example, tetramethylene diisocyanate, hexamethylene diisocyanate and dodeca methylene diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane, 4,4'-diisocyanatodicyclohexylmethane or also aromatic diisocyanates, such as 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, mixtures consisting of these isomers, 4,4'-diisocyanatodiphenylmethane, 1,5-diisocyanatonaphthalene, etc.

• 1. die in der Polyurethan-Chemie an sich bekannten Dihydroxypolyester aus Dicarbonsäuren, wie Bernsteinsäure, Adipinsäure, Korksäure, Azelainsäure, Sebacinsäure, Phthalsäure, Isophthalsäure, Terephthalsäure, Tetrahydrophthalsäure usw. und Diolen, wie z.B. Äthylenglykol, Propylenglykol-1,2, Propylenglykol-1,3, Diäthylenglykol, Butandiol-1,4, Hexandiol-1,6, Octandiol-1,8, Neopentylglykol, 2-Methypropandiol-1,3, oder die verschiedenen isomeren Bishydroxymethylcyclohexane;
• 2. die in der Polyurethan-Chemie an sich bekannten Polylactone, wie z.B. die auf den oben genannten zweiwertigen Alkoholen gestartete Polymerisate des F-Caprolactons;
• 3. die in der Polyurethan-Chemie an sich bekannten Polycarbonate, wie sie durch Umsetzung beispielsweise der oben genannten Diole mit Diarylcarbonaten oder Phosgen zugänglich sind;
• 4. die in der Polyurethan-Chemie an sich bekannten Polyäther, wie z.B. die unter Verwendung von zweiwertigen Startermolekülen, wie Wasser, den oben genannten Diolen oder 2 N-H-Bindungen aufweisende Amine hergestellten Polymerisate bzw. Mischpolymerisate des Styroloxids, Propylenoxids, Tetrahydrofurans, Butylenoxids oder Epichlorhydrins. Auch Äthylenoxid kann anteilmäßig mitverwendet werden mit der Maßgabe, daß der verwendete Polyäther maximal ca. 10 Gewichtsprozente an Äthylenoxid enthält. Im allgemeinen werden jedoch solche Polyäther eingesetzt, die ohne Mitverwendung von Äthylenoxid erhalten wurden;
• 5. die in der Polyurethan-Chemie an sich bekannten Polythioäther, Polythiomischäther, Polythioätherester;
• 6. die in der Polyurethan-Chemie an sich bekannten Polyacetale, beispielsweise aus den oben genannten Diolen und Formaldehyd; sowie
• 7. difunktionelle endständige, gegenüber Isocyanatgruppen reaktionsfähige Gruppen aufweisende Polyätherester.

Terminal compounds of the molecular weight range 300-6000, preferably 500-3000, which are difunctional in the sense of the isocyanate polyaddition and have groups which are reactive toward isocyanate, are particularly suitable for the process according to the invention

• 1. the dihydroxy polyesters known per se in polyurethane chemistry from dicarboxylic acids, such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid etc. and diols, such as, for example, ethylene glycol, 1,2-propylene glycol, propylene glycol 1,3, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentylglycol, 1,3-2-methypropanediol, or the various isomeric bishydroxymethylcyclohexanes;
• 2. the polylactones known per se in polyurethane chemistry, such as, for example, the polymers of F-caprolactone started on the above-mentioned dihydric alcohols;
• 3. the polycarbonates known per se in polyurethane chemistry, as can be obtained by reacting, for example, the abovementioned diols with diaryl carbonates or phosgene;
• 4. the polyethers known per se in polyurethane chemistry, such as, for example, the polymers or copolymers of styrene oxide, propylene oxide, tetrahydrofuran, butylene oxide or prepared using amine dihydric molecules such as water, the above-mentioned diols or 2 NH bonds Epichlorohydrins. Ethylene oxide can also be used proportionally, provided that the polyether used contains a maximum of about 10 percent by weight of ethylene oxide. In general, however, such polyethers are used which were obtained without the use of ethylene oxide;
• 5. the polythioethers, polythio mixed ethers, polythioether esters known per se in polyurethane chemistry;
• 6. the polyacetals known per se in polyurethane chemistry, for example from the diols and formaldehyde mentioned above; such as
• 7. difunctional terminal polyether esters which are reactive toward isocyanate groups.

In the novel process dihydroxy polyesters, dihydroxy polylactones, Dihydroxypolyäther and _D are preferably used ihydroxypolycarbonate.

In principle, however, the compounds according to the invention could also be used without the use of higher molecular weight polyhydroxyl compounds, i.e. can only be produced using diisocyanates and low molecular weight reactants (molecular weight <300).

The chain extenders of a molecular weight below 300 which are to be also used in the process according to the invention for the preparation of the water-soluble polyurethanes are, for example, the low molecular weight diols described in the preparation of the dihydroxy polyesters, or else diamines, such as diaminoethane, 1,6-diaminohexane, piperazine, 2,5-dimethylpiperazine, 1- Amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, 1,2-propylenediamine or hydrazine, amino acid hydrazides, hydrazides of semicarbazidocarboxylic acids, bis-hydrazides and bis-semicarbazides in Consider.

Suitable structural components are also e.g. Oleyl diethanolamine, stearyl diethanolamine, adducts of long-chain alkyl isocyanates with diethanolamine or other amino alcohols, esterification products of long-chain fatty acids with glycerol or trimethylolpropane, adducts of amines having 6-24 C atoms or phenols with glycide or 3-ethyl-3-hydroxymethyl-ox.

In addition to the structural components which are difunctional in the sense of the isocyanate polyaddition reaction, in special cases in which little branching of the polyurethanes is desired, the tri-functional and higher functional structural components known per se in polyurethane chemistry can also be used in small proportions. However, the starting components are preferably selected so that the functionality does not exceed an average of 2.1.

• a) beliebige Mono- oder Diisocyanate und/oder im Sinne der Isocyanatpolyadditionsreaktion mono- oder difunktionelle Verbindungen mit gegenüber Isocyanatgruppen reaktionsfähigen Wasserstoffatomen mit Äthylenoxid-Einheiten aufweisenden hydrophilen Ketten und
• b) beliebige Mono- oder Diisocyanate und/oder im Sinne der Isocyanatpolyadditonsreaktion mono- oder difunktionelle Verbindungen mit gegenüber Isocyanatgruppen reaktionsfähigen Wasserstoffatomen mit ionischen Gruppen oder in ionische Gruppen überführbaren Gruppen mitverwendet werden.

In the method according to the invention:

• a) any mono- or diisocyanates and / or in the sense of the isocyanate polyaddition reaction mono- or difunctional compounds with hydrogen atoms which are reactive towards isocyanate groups and have hydrophilic chains and ethylene oxide units
• b) any mono- or diisocyanates and / or in the sense of the isocyanate polyadditone reaction, mono- or difunctional compounds with hydrogen atoms which are reactive towards isocyanate groups and with ionic groups or groups which can be converted into ionic groups are also used.

und/oder Verbindungen der Formel

The preferred hydrophilic structural components with hydrophilic chains having pendant ethylene oxide units include both compounds of the formula

and / or compounds of the formula

Particularly preferred structural components a) are those of the first-mentioned formula (I).

• R für einen zweiwertigen Rest, wie er durch Entfernung der Isocyanatgruppen aus einem Diisocyanat der Formel R(NCO)₂ der vorstehend genannten Art erhalten wird,
• R' für Wasserstoff oder einen einwertigen Kohlenwasserstoffrest mit 1 bis 8 Kohlenstoffatomen, vorzugsweise für Wasserstoff oder eine Methylgruppe,
• R" für einen einwertigen Kohlenwasserstoffrest mit 1 bis 12 Kohlenstoffatomen, vorzugsweise einen unsubstituierten Alkylrest mit 1 bis 4 Kohlenstoffatomen,
• X für den Rest, wie er durch Enfernen des endständigen Sauerstoffatoms aus einer Polyalkylenoxidkette mit 5 bis 90, vorzugsweise 20 bis 70 Kettengliedern erhalten wird, welche Kettenglieder zumindest zu 40 %, vorzugsweise zumindest zu 65 % aus Äthylenoxid-Einheiten bestehen und die neben Äthylenoxid-Einheiten auch Propylenoxid-, Butylenoxid- oder Styroloxid-Einheiten darstellen können, wobei unter den letztgenannten Einheiten Propylenoxid-Einheiten bevorzugt sind,
• M Y für Sauerstoff oder -NR -, wobei R" bezüglich seiner Definition R" entspricht,
• Z für einen Rest, der in seiner Bedeutung der Definition von Y entspricht.

In formulas (I) and (II) above

• R represents a divalent radical as obtained by removing the isocyanate groups from a diisocyanate of the formula R (NCO) _{2 of} the type mentioned above,
• R 'represents hydrogen or a monovalent hydrocarbon radical having 1 to 8 carbon atoms, preferably hydrogen or a methyl group,
• R "for a monovalent hydrocarbon radical having 1 to 12 carbon atoms, preferably an unsubstituted alkyl radical having 1 to 4 carbon atoms,
• X for the rest, as is obtained by removing the terminal oxygen atom from a polyalkylene oxide chain with 5 to 90, preferably 20 to 70, chain links, which chain links consist of at least 40%, preferably at least 65%, of ethylene oxide units and which, in addition to ethylene oxide units Units can also be propylene oxide, butylene oxide or styrene oxide units, propylene oxide units being preferred among the latter units,
• MY for oxygen or -NR -, where R "corresponds to R by definition",
• Z for a residue whose meaning corresponds to the definition of Y.

The compounds of the formulas (I) and (II) mentioned above can be prepared in accordance with the procedures of DT-OS 2 314 512 or 2 314 513, the addition of Disclosure made there is pointed out that, instead of the polyether alcohols mentioned there as starting material, it is also possible to use those whose polyether segment, in addition to ethylene oxide units, is also preferably up to 60% by weight, based on polyether segment, of propylene oxide, butylene oxide or styrene oxide Have propylene oxide units. The proportion of such "mixed polyether segments" can bring specific advantages in special cases.

Dihydroxy polyethers having a molecular weight of 300-6000, preferably 500-3000, also containing ethylene oxide units can also be used as a hydrophilic structural component in the process according to the invention. Also hydrophilic ether groups, i.e. Dihydroxypolycarbonates containing polyethylene oxide units are suitable as a hydrophilic structural component.

und/oder Verbindungen der Formel

wobei

• x, Y, Z, R, R" die oben erläuterte Bedeutung haben.

Further particularly preferred hydrophilic structural components for the incorporation of terminal or pendant hydrophilic chains of ethylene oxide units are compounds of the formula

and / or compounds of the formula

in which

• x, Y, Z, R, R "have the meaning explained above.

Structural components b) essential to the invention are, for example in the sense of the isocyanate polyaddition reaction, monofunctional or difunctional representatives of the compounds mentioned by way of example in US Pat. No. 3,479,310, column 4, line 11 to column 5, line 46, or the corresponding compounds accessible by simple neutralization or quaternization with salt-like groups. Suitable neutralizing or quaternizing agents are, for example, the compounds mentioned in the US patent mentioned in column 6, lines 14 to 39.

For the incorporation of tertiary sulfonium groups in the polyurethane, for example, the compounds listed in US Pat. No. 3,419,533, column 3, line 75 to column 4, line 51 are used as synthesis components.

In principle, it does not matter how the cationic centers were built into the polyurethane. So you can e.g. In addition to the methods listed in the two mentioned patents, also produce a polyurethane or NCO prepolymer bearing epoxy groups and introduce the basic center by reaction of the epoxy group with a primary or secondary amine, which is then converted into the salt form by an inorganic or organic acid or an alkylating agent becomes.

In the process according to the invention, the type and amount of components a) are chosen such that 2 to 50, preferably 11 to 20,% by weight of -CH ₂ -CH ₂ -O- ethylene oxide units built into the ether segments are present in the polyurethanes according to the invention. The type and quantity or the neutralization or The degree of quaternization of components b) is chosen in the process according to the invention such that 16 to 250 milliequivalents per 100 g, preferably 20 to 100 milliequivalents per 100 g of = N ^⊕ =, -COO ⁶ or -S - groups are present in the polyurethanes according to the invention. The sum of the number of milliequivalents of incorporated ionic groups per 100 g of polyurethane and the number of “pseudomillie equivalents” of incorporated ethylene oxide units per 100 g of polyurethane is 40 to 300 and particularly preferably between 60 and 200.

A “pseudomilli equivalent” of built-in ethylene oxide units is to be understood here as the amount of ethylene oxide units built into a polyalkylene oxide chain, which makes the same contribution to the solubility of the polyurethane in water as one milliequivalent of built-in ionic groups. (The effectiveness of the above-mentioned ionic groups with regard to their contribution to the solubility of the polyurethane depends exclusively on the number of milliequivalents of ionic groups and not on the type of the ionic groups.) In the case of aqueous polyurethane solutions, the solubility depends on the concentration of the hydrophilic centers built into the polyurethane from. As it turned out on the basis of detailed studies by the applicant, in any water-soluble, exclusively ionically modified polyurethane with an otherwise completely analogous molecular structure, the ionic groups can always be replaced by a certain amount of ethylene oxide arranged within a polyether chain, so that a corresponding one is exclusively non-ionic modified polyurethane is obtained, which has the same solubility in water, (with an analogous preparation of the polyurethane solutions is assumed) if the milliequivalents of ionic groups present in the ionically modified polyurethane are replaced by the same number of "pseudomilliequivalents" of nonionic groups. One milliequivalent of built-in ionic groups corresponds to 0.5 g of ethylene oxide units built into a polyether chain. A “pseudomilli equivalent” of nonionic groups is therefore to be understood as meaning 0.5 g of ethylene oxide units incorporated within a polyether chain. Accordingly, an exclusively ionically modified polyurethane with a content of 40 milliequivalents per 100 g of one of the above-mentioned ionic groups has the same water solubility as an analogue constructed and produced exclusively nonionically modified polyurethane with a content of 20 g per 100 g of that incorporated within a polyether chain Ethylene oxide.

The process according to the invention for the preparation of the water-soluble polyurethanes can be carried out according to the methods of polyurethane chemistry known per se, both according to the one-step and the two-step process (prepolymer process).

In the production of the water-soluble polyurethanes, the reactants are used in an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 0.8: 1 to 2.5: 1, preferably 0.95: 1 to 1.5: 1. When an excess of NCO is used, this naturally results in compounds having NCO groups which, when converted into an aqueous solution, react further with the water with chain extension to the end product. Accordingly, the above equivalent- ratio of all components involved in the construction of the polyurethanes according to the invention, including the chain extender containing amino groups, which may be used in the form of aqueous solutions, but not the proportion of the water used to dissolve the polyurethanes, which reacts with compounds which may contain NCO groups to give a chain extension reaction. In the context of the present invention, any carboxyl groups (component b)) which may be present in the reaction mixture are not regarded as groups which are reactive towards isocyanate groups, which is justified in view of the inertness of these groups towards isocyanate groups.

Both the one-step and two-step processes can be carried out in the presence or absence of solvents. Suitable solvents, in particular if, as described below - during or after the polyurethane production is intended to convert the polyurethanes into an aqueous solution, are, for example, water-miscible solvents which are indifferent to isocyanate groups and have a boiling point below 100 ° C, e.g. Acetone or methyl ethyl ketone.

When carrying out the one-step process, preference is given to the difunctional terminal compounds of molecular weight range 500 to 6000 mentioned above under 1 to 7 and having groups which are reactive toward isocyanate groups, with the hydrophilic chain extenders a) and b) and the chain extender which may also be used a molecular weight below 500 mixed. The diisocyanate component is then added to the mixture thus obtained in the absence of solvents, after which the reaction mixture is preferably brought to reaction at temperatures of from 50 to 150 ^° C., optionally after addition of the catalysts known per se in polyurethane chemistry. The amount of the diisocyanate components is chosen so that there is an NCO / OH ratio of 0.8 to 1.05. During the reaction, the viscosity of the reaction mixture increases, so that one of the solvents mentioned is gradually added to the mixture. Finally, an organic solution of the aureacted polyurethane is obtained, the concentration of which is preferably adjusted to 10 to 70, in particular 15 to 55,% by weight of solids. In this one-step process, the use of tertiary amines with 2 alcoholic hydroxyl groups as component b) is particularly recommended. If compounds are used as component b) which have groups which can be converted into ionic groups, this conversion by neutralization or quaternization known per se following the polyaddition reaction is recommended either in organic solution or in such a way that the polyurethane present in organic solution during its conversion is neutralized in an aqueous solution by neutralizing agents present in the water.

The polyurethanes are advantageously converted into an aqueous solution by adding water to the stirred solution or melt. After removal of any solvent present by distillation, a purely aqueous solution remains.

When carrying out the two-stage process, the first step is preferably in the melt of excess diisocyanate, higher molecular weight compound with groups of the type mentioned above under 1 to 7 which are reactive towards isocyanate groups, and hydrophilic chain extender a) and optionally b) while maintaining an NCO / OH ratio from 1.1: 1 to 3.5: 1, preferably 1.2: 1 to 2.5: 1, in the absence of solvents or even in the presence of solvents, an NCO prepolymer is prepared, which is then used in the absence of solvents, for example, is taken up in a suitable solvent. The solution of the prepolymer thus obtained can then be reacted in a manner known per se with the chain extender of the type exemplified above having a molecular weight below 300. For the preparation of the polyurethane solutions according to the invention, a special variant of the two-stage process is recommended, in which the described solution of the NCO prepolymer with the solution of the chain extender - here the diamines or hydrazine derivatives mentioned are preferably used as chain extenders - in small amounts of water or a water / solvent mixture so offset that the NCO / NH ratio is between 2.5 and 1.05. This reaction can take place at room temperature or preferably at 25-60 ° C. By subsequently adding the remaining water and then removing the solvent, the aqueous polyurethane solution is finally obtained. However, in this process variant it is also possible to add the chain extender in the total amount of water finally present in the solution (50-200% by weight, based on solid polyurethane) to solve. When carrying out the two-stage process, it is entirely possible and often also preferred not to incorporate component b) into the prepolymer, but rather to use aqueous solutions of diaminocarboxylates in the chain extension reaction described instead of or in combination with the diamines or hydrazine derivatives mentioned above.

However, the two-stage process described is preferably carried out without solvent without major difficulties, namely in such a way that the NCO prepolymer described is prepared solvent-free and stirred into the water as a melt, the ionic or nonionic chain extenders containing amino groups mentioned here also being able to be present in water-soluble form .

Of course, it is also possible, as is usual with solid thermoplastics, to build up the melt from the components, e.g. in a form, on a steel belt or in a screw, to crush the solid product and then to dissolve it in water.

• i) der Formel
  
  oder
• ii)der Formel
  
  verbunden, wobei
  • R, R", R'", X, Y und Z die oben genannte Bedeutung haben.

The water-soluble polyurethanes according to the invention have a predominantly linear molecular structure and are from 2 to 50% by weight, preferably from 11 to 20% by weight, of ethylene oxide incorporated within a polyether chain and from = N =, -COO or -S - - Groups of 16 to 250, preferably 20 to 100 milliequivalents per 100 g characterized. The lateral polyalkylene oxide chain, which has the ethylene oxide units essential to the invention, is preferred via groupings

• i) the formula
  
  or
• ii) of the formula
  
  connected, being
  • R, R ", R '", X, Y and Z have the meaning given above.

in welcher

• R, X, Y, R" und R''' die vorstehend genannte Bedeutung haben.

The variant of the method according to the invention described above represents only a preferred, but not the only, route to the polyurethanes according to the invention. Another route to the polyurethanes according to the invention is, for example, the introduction of the nonionic pendant hydrophilic groups into an already ionic group or one which can be converted into ionic groups Group-containing, preferably linear polyurethane elastomer by reacting this elastomer with hydrophilic monoisocyanates of the formula

in which

• R, X, Y, R "and R""have the meaning given above.

Such hydrophilic monoisocyanates are produced in analogy to the procedure described in German Offenlegungsschrift No. 2,314,512, but here too in addition to those made there Disclosure is pointed out that instead of the monofunctional polyether alcohols mentioned there as the starting material, it is also possible to use those whose polyether segment in addition to ethyl hydroxide units also contains up to 60, preferably up to 35% by weight, based on polyether segment, of propylene oxide, butyl oxide or styrene oxide , preferably have propylene oxide units.

In the production of the polyurethanes according to the invention using these hydrophilic monoisocyanates, a linear polyurethane is preferably produced from the starting materials mentioned using an equivalent ratio of isocyanate groups: preferably 1: 1 groups which are reactive towards isocyanate groups, but which still contain ionic groups or groups which can be converted into ionic groups has no hydrophilic polyether segments. This linear polyurethane elastomer is then reacted in the melt or in a suitable solvent, for example of the type mentioned above, at 50 to 150 ° C. with the hydrophilic monoisocyanates, in particular an addition of the isocyanate group of the hydrophilic monoisocyanate to the active hydrogen atoms of the urethane present in the linear polyurethane. and / or urea groups occurs. Any groups that can be converted into ionic groups are then at least partially converted into the corresponding ionic groups by neutinelization or quaternization known per se. In this embodiment of the production of the polyurethanes according to the invention, when using structural components containing carboxyl groups, the carboxyl groups of which are subsequently to be converted into carboxylate groups by neutralization, care should be taken to ensure that only compounds containing carboxyl groups are used whose carboxyl groups are less reactive towards isocyanate groups than isocyanate groups as urethane or urea groups.

umsetzen. Hierbei haben R, X, Y, R" die vorstehend genannte Bedeutung.Furthermore, a procedure is particularly preferred according to which a prepolymer with terminal NCO groups is reacted with a monofunctional hydrophilic polyether, so that a polymeric polyurethane with terminal hydrophilic polyether segments is formed. Of course, such a product can also be obtained by a one-step process in that a corresponding hydrophilic monofunctional polyether is also used as a structural component in the construction of the polyurethane. Finally, it is of course also possible to use a prepolymer with terminal OH, SH, NH ₂ , NHR or COOH groups with a hydrophilic monoisocyanate of the formula

implement. Here R, X, Y, R "have the meaning given above.

gekennzeichnet, wobei

• U für -O-CO-NH-, -NH-CO-NH-, -NH-CO-, -S-CO-NH- steht und
• R, X, Y, R" die vorstehend genannte Bedeutung haben.

This group of polyurethanes according to the invention is by the grouping

featured, where

• U stands for -O-CO-NH-, -NH-CO-NH-, -NH-CO-, -S-CO-NH- and
• R, X, Y, R "have the meaning given above.

If polyurethanes with terminal monofunctional hydrophilic polyethers are produced, preference is given to at least little branching of these products, e.g. through partial use of trifunctional or polyfunctional structural components or through partial allophanatization, trimerization or biuretization.

The polyurethane according to the invention obtained in this way as a melt or as a solution can then be converted into an aqueous solution by mixing with water and, if appropriate, then distilling off the auxiliary solvent.

The aqueous polyurethane solutions according to the invention are clear and also show a solids content of e.g. 5-10% no Tyndall effect. At room temperature, layers that have dried out of the solutions dissolve smoothly and sparingly in water.

Despite their relatively high ionic group content, the solutions are largely insensitive to electrolytes; this allows, for example, acid-catalyzed crosslinking with formaldehyde or formaldehyde derivatives; their pigmentation with electrolyte-active pigments or dyes is also possible. Another characteristic of fiction, contemporary ⁼ dispersions is their compatibility with alum solutions in paper sizing.

The solutions of the polyurethane masses in water are stable, can be stored and shipped and can be used at any later time, e.g. B. proactive, processed. They generally dry directly to form stable plastic coatings, but the process products can also be shaped in the presence of crosslinking agents known per se. Depending on the chosen chemical composition and the content of urethane groups, polyurethanes with different properties are obtained. This means that soft, sticky tills, thermoplastic and rubber-elastic products from the various degrees of hardness up to glass-hard thermosets can be obtained. The hydrophilicity of the products can also fluctuate within certain limits. The elastic products can be used at higher temperatures, e.g. 1 ₀₀ - 180 ° C. process thermoplastic, provided that they are not chemically cross-linked.

The process products are used for coating or for covering and impregnating woven and non-woven textiles, leather, paper, wood, metals, ceramics, stone, concrete, bitumen, hard fiber, straw, glass, porcelain, all kinds of plastics, glass fibers antistatic and wrinkle-free finish, as a binder for nonwovens, adhesives, adhesion promoters, laminating agents, water repellents, plasticizers, binders, e.g. B. for cork or wood flour. Glass fibers, asbestos, paper-like materials, plastic or rubber wastes, ceramic materials, as aids ic stuff printing and in the paper industry, as an additive to polymers, as sizing agents, for example for glass fibers. and suitable for leather finishing.

By using vinyl polymers or active or inactive fillers, you can modify the properties of the process products. For example, polyethylene, polypropylene, polyvinyl acetate, ethylene-virylacetate copolymers, which can optionally be (partially) saponified / or grafted with vinyl chloride, styrene-butadiene copolymers, ethylene- (graft) -copolynerizates, polyacylates, carbon black, silica, can be used , Asbestos, talc, kaolin, titanium dioxide, glass as powder or in the form of fibers, cellulose. Depending on the desired property profile and intended use of the end products, up to 70%, based on the total amount of cesamite, of such fillers can be present in the end product.

Of course, dyes, fillers, pigments, plasticizers or additives influencing the rheological properties can also be added, likewise e.g. Polymer dispersions, soot and cresolic acid brines.

The products obtained by various application techniques can be dried at room temperature or at elevated temperature.

The following examples are intended to explain the composition, manufacture and some physical properties.

example 1

• i) eines Polyäthermonoalkohols aus n-Butanol, Äthylenoxid und Propylenoxid (im Gewichtsverhältnis 83:17) der OHZ 30;
• ii) Hexandiisocyanat-1,6 und
• iii) Diäthanolamin

hergestellt wird und ein mittleres Molekulargewicht von 2140 aufweist, 1 Stunde bei 120°C und 15 Torr im Wasserstrahlpumpen- Vakuum entwässert. Man läßt auf 80°C abkühlen, fügt 102,3 g Hexandiisocyanat-1,6 zu und rührt 2 Stunden bei 120°C nach. Das erhaltene Prepolymer weist einen NCO-Gehalt von 2,07 % auf, es wird unter Kühlung mit 100 ml Aceton verdünnt, dann werden bei 60°C (Badtemperatur) 9,5 g (0,08 Mol) N-Methyldiäthanolamin zugegeben und 1 Stunde bei 60°C Außentemperatur verrührt. Man verdünnt bei konstanten Temperaturbedingungen mit weiteren 200 ml Aceton, fügt 1,6 g (0,022 Mol) 1,2-Diaminopropan in 50 ml Aceton gelöst zu, rührt eine Stunde nach und quaterniert dann eine Stunde mit 9,5 g (0,075 Mol) Dimethylsulfat. Die Ammoniumsalzbildung wird durch Zugabe von 8 g H₃P0₄ (85 %ig) gelöst in 50 ml Wasser vervollständigt, man rührt weiter bei 60°C Außentemperatur bis sich IR-spektroskopisch kein NCO mehr nachweisen läßt (was im allgemeinen nach 1 Stunde der Fall ist) und verdünnt bei 50°C mit 750 ml Wasser. Nach Abdestillation des Acetons bei 50°C im Wasserstrahlpumpenvakuum verbleibt eine kationische Polyurethanlösung mit einem Feststoffgehalt von 37,5 Gew.-%, einer Viskosität von 700 cP bei 22°C, einem pH von 2,4 sowie bezogen auf 100 g Polyurethan 20 Milliäquivalenten an quatärem Stickstoff und 100 PseudoMilliäquivalenten an Äthylenoxid-Einheiten. 50 g dieser auf 10 % Feststoff eingestellten Polyurethanlösung können mit 10 g einer 10 %igen Kochsalzlösung vermischt werden, ohne daß Koagulation eintritt (s. allgemeine Vorschrift zur Bestimmung der Elektrolytstabilität ionischer PU-Lösungen).262 g (0.444 mol) of a polyethylene oxide / polypropylene oxide diol started on propylene glycol with a proportion of polyethylene oxide of 70% by weight, OHZ 190 together with 50 g (0.023 mol) of a nonionic-hydrophilic chain extender, which is analogous to the procedure described in U.S. Patent 3,905,929 by converting equivalent parts

• i) a polyether monoalcohol from n-butanol, ethylene oxide and propylene oxide (in a weight ratio of 83:17) of the OHZ 30;
• ii) 1,6-hexane diisocyanate and
• iii) Diethanolamine

is produced and has an average molecular weight of 2140, dewatered for 1 hour at 120 ° C. and 15 torr in a water-jet pump vacuum. The mixture is allowed to cool to 80 ° C., 102.3 g of 1,6-hexane diisocyanate are added and the mixture is stirred at 120 ° C. for 2 hours. The prepolymer obtained has an NCO content of 2.07%, it is diluted with 100 ml of acetone while cooling, then 9.5 g (0.08 mol) of N-methyldiethanolamine are added at 60 ° C. (bath temperature) and 1 Hour at 60 ° C outside temperature. The mixture is diluted with a further 200 ml of acetone at constant temperature conditions, 1.6 g (0.022 mol) of 1,2-diaminopropane dissolved in 50 ml of acetone are added, the mixture is stirred for one hour and then quaternized with 9.5 g (0.075 mol) for one hour Dimethyl sulfate. The ammonium salt formation is completed by adding 8 g of H ₃ PO ₄ (85%) dissolved in 50 ml of water, stirring is continued at an external temperature of 60 ° C. until no more NCO can be detected by IR spectroscopy (which generally occurs after 1 hour Case) and diluted at 50 ° C with 750 ml of water. After distilling off the Acetone at 50 ° C in a water pump vacuum remains a cationic polyurethane solution with a solids content of 37.5% by weight, a viscosity of 700 cP at 22 ° C, a pH of 2.4 and, based on 100 g of polyurethane, 20 milliequivalents of quaternary nitrogen and 100 pseudo-milliequivalents of ethylene oxide units. 50 g of this polyurethane solution adjusted to 10% solids can be mixed with 10 g of a 10% saline solution without coagulation occurring (see general regulation for determining the electrolyte stability of ionic PU solutions).

General regulation for determining the electrolyte stability of ionic PU solutions

50 ml of an ionic PU solution adjusted to 10% solids are placed in an Erlenmeyer flask and 10% aqueous NaCl solution is added dropwise from a supply burette with vigorous stirring using a magnetic stirrer at room temperature. After increasing turbidity, sudden coagulation of the solution usually occurs, at least when saline solution is <20 ml. With even higher electrolyte stability, the end point determination can sometimes be difficult, since coagulation occurs only slowly with partial flocculation. In this case, the end point determination is made easier by adding the saline solution in 5 ml portions, stirring for 5 minutes after each addition and then making the assessment.

Example 2

177 g (0.300 mol) of a polyether diol started on propylene glycol according to Example 1 and 175 g (0. 100 mol) of a polyester diol consisting of adipic acid, phthalic anhydride and ethylene glycol and 107.5 g (0.050 mol) of the nonionically hydrophilic chain extender according to Example 1 were dewatered for one hour at 120 ° C., 15 torr, cooled to 80 ° C. and mixed with 109 g (0.650 mol) of hexane diisocyanate. The mixture is stirred at 120 ° C. for 2 hours, resulting in a prepolymer with an NCO content of 2.19%. Dilute with 200 ml of acetone while cooling. At a bath temperature of 60 ° C., 11.9 g (0, 100 mol) of N-methyldiethanolamine are added and the mixture is stirred at 60 ° C. for 60 minutes. At the same temperature, 3.6 g (0.050 mol) of 2-diaminopropane are added, the mixture is diluted with a further 200 ml of acetone and stirred for 60 minutes, and then quaternized with 11.9 g (0.094 mol) of dimethyl sulfate. One hour later, to remove NCO groups still detectable in the IR spectrum, 80 g of water are added and a total of a further 1200 ml of acetone are diluted, and 8 g of phosphoric acid (85% strength) are added to the acetone polyurethane solution which is free of NCO after 3 hours. At 50 ° C is diluted with 1.4 l of water preheated to 50 ° C and the acetone is distilled off in a water jet pump vacuum. A cationic, aqueous polyurethane solution is obtained which has a viscosity of 4500 cP and a solids content of 20.5% and a pH of 2.3 at 22 ° C. ¹⁾ . 50 ml of the solution adjusted to 10% solids can be mixed with 25 ml of a 10% saline solution before the first visible precipitation occurs.

1) Based on 100 g of solid, the solution contains 17 milliequivalents of N ⁺ and 68 pseudo milliequivalents of ethylene oxide units.

Example 3 (comparative example)

As a comparative example to Example 2, a similar polyurethane solution was prepared without hydrophilic ethylene oxide units, the proportion of quaternary nitrogen being increased so that it corresponded to the sum of milliequivalents of quaternary nitrogen and pseudomilliequivalents of ethylene oxide according to Example 2.

Composition:

The aqueous polyurethane solution was prepared according to Example 2. The resulting cationic polyurethane solution has a solids content of 31% by weight, a viscosity of 600 cP at 22 ° C. and a pH of 1.8. Based on 100 g of solid, the solution contains 85 milliequivalents of quaternary nitrogen. 50 ml of the solution adjusted to 10% solids coagulate when less than 1 ml of a 10% saline solution is added.

Example 4

133 g (0.074 mol) of a polyester diol from adipic acid and tetraethylene glycol with an average molecular weight of 1800 and 125 g (0.058 mol) of the nonionic-hydrophilic chain extenders according to Example 1 are dewatered at 15 Rorr and 120 ° C. for 30 minutes, cooled to 80 ° C. and 61.3 g of 1,6-hexane diisocyanate are added. After stirring for 2 hours at 120 ° C., a prepolymer with an NCO content of 5.35% by weight is obtained. With cooling, the mixture is diluted with 100 ml of acetone, at 60 ° C (bath temperature), 23.8 g (0, 200 mol) of N-methyldiethanolamine are diluted with 50 ml of acetone, stirred for one hour at 60 ° C, 0.25 g ( 0, 003 mol) 1,2-diaminoproo pan added and quaternized one hour later at the same temperature with 23, 8 g (0, 189 mol) of dimethyl sulfate. 30 minutes after the dimethyl sulfate. 20 ml of water are added, the mixture is then stirred at a bath temperature of 60 ° C. until NCO can no longer be detected by IR spectroscopy. 6 g of 85% phosphoric acid and then 900 ml of water are added and the acetone is removed at 50 ° C. in a water jet vacuum. The resulting aqueous polyurethane solution has a solids content of 30% by weight, a viscosity of 67 cP at 22 ° C. and a pH of 2.3. 100 g of solid contain 53 milliequivalents of quaternary nitrogen and 50 pseudomilliequivalents of ethylene oxide units. 50 ml of a sample of this solution adjusted to 10% solids tolerate the addition of 100 ml of a 10% saline solution without coagulation occurring.

Example 5:

230 g of a technical polyethylene glycol mixture with an average molecular weight of 230 (as is the case in the distillation of tetraethylene glycol as a residue) and 119 g of N-methyldiethanolamine mixed together and at 80 ° C 262 g of a technical polyisocyanate mixture as it is obtained as a distillation residue in the production of hexane diisocyanate 1,6 (NCO content approx. 32% by weight) are slowly added dropwise. 30 minutes after the end of the dropping, NCO can no longer be detected by IR spectroscopy. 173 g of phosphoric acid (85% strength) and 1769 g of water are now added simultaneously with cooling. The resulting thin-bodied polyurethane solution has a pH of 1.6 at a solids content of 30% by weight. 50 ml of a sample of this dispersion adjusted to 10% solids tolerate 100 ml of a 10% saline solution without coagulation.

Claims (2)

1) Electrolyte-stable aqueous solutions of polyurethane ionomers with an essentially linear molecular structure, characterized by a) hydrophilic polyalkylene oxide-polyether chains with a content of bound ethylene oxide units of 2 to 50 wt .-%, based on the entire polyurethane, and b) a content of -N ^⊕ =,

or -C00 ^⊖ groups from 16 to 250 milliequivalents per 100 g. 2) Process for the production of water-soluble polyurethanes with an essentially linear molecular structure by reacting organic diisocyanates with organic compounds of the molecular weight range 300 to 6000 which have difunctional hydrogen atoms which are reactive toward isocyanate groups, in the sense of the isocyanate polyaddition reaction, using structural components which ensure the solubility of the polyurethanes with hydrophilic components Groups or groups which can be converted into such hydrophilic groups, the at least partial conversion of the latter groups into hydrophilic groups taking place during or after the polyaddition reaction, and optionally also using the chain extenders known per se in polyurethane chemistry and having a molecular weight below 300 and optionally also using them the auxiliaries and additives customary in polyurethane chemistry, characterized in that as Au construction components with hydrophilic groups or with groups which can be converted into hydrophilic groups a) mono- or diisocyanates and / or in the sense of the isocyanate polyadditone reaction mono- or difunctional compounds with hydrogen atoms reactive towards isocyanate groups with hydrophilic chains having ethylene oxide units as well b) mono- or diisocyanates and / or in the sense of the isocyanate polyaddition reaction, mono- or difunctional compounds having hydrogen atoms which are reactive toward isocyanate groups and having ionic groups or groups which can be converted into ionic groups
be used, the type and amount or degree of neutralization or degree of quaternization of components a) and b) being such that in the ultimately obtained polyurethane 2 to 50 wt .-% of built-in ethylene oxide units and 16 to 250 milliequivalents per 100 g present on ionic groups.