CA2219835A1 - Dispersions containing polyurethanes having carbonyl groups in keto function - Google Patents

Abstract

Aqueous dispersions containing a polyurethane(A) having structural units derivedfrom compounds of the formula (I) (see fig. I) in which the substituents have the following meanings:
R1, R2, R3 independently denote hydrogen, C1-C24 alkyl or C6-C24 alkenyl R4 denotes hydrogen R5, R6 (a) together denote C4-C10 alkanediyl, (b) each denotes C2-C10 alkyl, C5-C8 cycloalkyl or C7-C20 aralkyl, (c) each denotes a hydroxyl-terminated poly(C2-C4 alkylene oxide), or (d) one radical R5 or R6 has the meaning stated under (a) to (c) and the other is hydrogen or a radical of the formula II

(see fig. II) in which X denotes C2-C6 alkanediyl and R7 has the same meaning as R5 or R6 except that R7 does not denote a radical of the formula II, where .
- the radicals R5 and R6 in each of the cases (a) and (d) carry a total of one (1 ) hydroxyl group attached to an aliphatic carbon atom, - optionally the radical R5 and/or R6 carries 1 or 2 hydroxyl groups bonded to an aromatic carbon atom or one nitrile, tertiary amino, carboxylic acid or sulfonic acid group which are optionally present in the form of their salts, and- the average functionality (F) of all structural components of the polyurethane (A) is from 1.5 to 2.2, based on the functionalities which interreact during thesynthesis of the polyurethane (A) in an addition reaction.

Description

~ CA 0221983~ 1997-11-20 : ~ASFA~ eCHAFT o.z.~oso/47497 Dispersions Containing Polyurethanes Having Carbonyl Groups In Keto Function Description The present invention relates to aqueous dispersions containing a polyurethane(A) having structural units derived from compounds of the formula (I) s R1R2CH - Cl - CR3R4 - C - NR5R6 (1), O O
in which the substituents have the following meanings:
,0 R1,R2,R3 independently denote hydrogen, C1_C24 alkyl or CB_C24 alkenyl R4 denotes hydrogen R5R6 a) together denote C4-C10 alkanediyl, b) each denotes C2-C10 alkyl, C5-C8 cycloalkyl or C7-C20 aralkyl, C) each denotes a hydroxyl- terminated poly(C2-C4 alkylene oxide), or d) one radical R5 or R6 has the meaning stated under (a) to (c) and the other is hydrogen or a radical of the formula 11 R1R2CH - C - CR3R4 - C - N - X (Il), Il 11 O O

in which X denotes C2-C6 alkanediyl and R7 has the same meaning as R5 or R6 except that R7 . does not denote a radical of the formula 11, where CA 0221983~ 1997-11-20 BASFAKTIENaEsE~LscHA~ o.z.ooso/47497 - the radicals R5 and R~ in each of the cases (a) and (d) carry a total of one (1) hydroxyl group attached to an aliphatic carbon atom, - optionally the radical R5 and/or R6 carries 1 or 2 hydroxyl groups bonded to s an aromatic carbon atom or one nitrile, tertiary amino, carboxylic acid or suifonic acid group which are optionally present in the form of their salts, and - the average functionality (F) of all structural components of the polyurethane(A) is from 1.5 to 2.2, based on the functionalities which interreact during thesylllhesis of the polyurethane (A) in an addition reaction.

Aqueous dispersions containing polyurethanes are well known (cf D. G. Oertel ~Kullslslorr Handbuch 7", 2nd Edition 1983, Carl Hanser Verlag Munich Vienna,pp 24 to 25 and pp 571 to 574). It is also known that it is possible to use the 15 polyurethane dispersions as coating compositions, eg as coating compositions or printing inks.

From a processing and economical point of view and with regard to the desirable properties of the coatings produced from the coating compositions the poly-20 urethane dispersions must in this case comply with a number of requirements nothitherto satisfied to the required extent.

Coating compositions are frequently required to satisfy the following conditionswith reference to their performance characteristics:

The coating compositions should be storable for a lengthly period of time without the properties thereof (eg rheological properties) or the properties of the coatings produced thererlom changing and without generating gas, since the formation of gas makes storage in tightly sealed containers virtually impossible.

- The coating compositions should contain minimal amounts of solvents, levellingagents or other readily volatile organic components, in order to minimize the emissions of organic compounds when applying and drying the coating com-positions.

- Following application to the workpiece the coating composition should dry or cure rapidly so that it is ready for use or can be further processed after only a short period of time.

40 - During processing of the coating compositions they should show a minimum tendency to foam.

CA 0221983~ 1997-11-20 SFAKTI~NGEsELLscHAF~ o.z.oo50/47497 High-quality coatings and surfaces of polyurethane coating compositions are required to satisfy a combination of the following conditions:

- Smooth surface and high gloss - Resistance to moisture, steam and chemicals such as dilute alkalis and acids and also organic solvents or surfactants - Insensitivity to mechanical stresses such as impact, shock or friction - No intrinsic color or defects such as bubbles or cracks - In the case of wood as substrate the coating compositions should cause the visible structure of the wood to become more evident (inflammation).

The development of coatings having such a combination of properties is hampered by the fact that the individual processing properties appear to be based on diverging structural properties. Whilst the abrasion resistance demands a certain degree of hardness, the impact strength requires a certain degree of elasticity.20 Furthermore a glossy surface requires good levelling characteristics of the coating composition, which generally demands use of volatile organic compounds as levelling agents.

In particular the coating compositions should be capable of being processed by a25 maximum number of conventional processes. The various processes involving various expenditure, where the expenditure correlates with the quality the produced therewith, are required, to make it possible to prepare coatings as economically as possible which satisfy a very specific quality level; for an increase in expenditure is often justified only when there is a corresponding increase in the 30 quality level. On the other hand the user is conrro,lled by considerable logistic problems if he is to have at hand a different coating composition starting material for each processing method. A particularly important part is played by the following processing methods:

35 The cold-curing process (final curing of the coating at room temperature) using a single-component coating system is the least elaborate and should satisfy moderate quality requirements.

The cold-curing process using a two-component coating system, which compli-cates the process for the user on account of the fact that he has to blend the CA 0221983~ 1997-11-20 BAsFAr I 1.... ' _ I ~CHAFT ~ o.z.ooSo/47497 coating system and the restricted processing time he has to complete blending, should satisfy more stringent quality requirements.

The baking method (final curing at temperatures usually of from 100~ to 1 60~C) is 5 suitable for the preparation of coatings meeting the highest quality standards.

Printing inks should usually satisfy the same criteria as regards their performance characteristics, as have already been mentioned with regard to the coating composilions (varnishes). On the other hand, the fulfilment of further demands that are specific to printing inks is important:

- High concentration of solid materials and particularly pigments so that the drying times are minimal and - good levelling characteristics on polar and non-polar substrates such as polyethylene and polypropylene Requirements to be met by articles printed with the printing inks, particularly those comprising non-polar plastics materials, are:

- Good-adhesion of the inks to the substrate especially under the action of water - Resistance of the inks to conventional solvents, fats, surfactants, aqueous 25 solutions, acids and alkalis - Good fastness properties.

Even in the case of this set of criteria conflicts of aims result in some instances, 30 which are only insufficiently solved using the printing inks of the prior art. It is known, for example, that the levelling characteristics of the printing inks can be improved by the addition of surfactant; however, the applied inks exhibit a lack of resistance to water. The wettability can also be improved by the addition of solvent, which, however restricts the ecological advantages of the water-based 35 inks.

Polyurethane dispersions which are suitable for use as single-component systems for coating various sul~lrates are described in EP-B 0,332,326. They contain notonly a water-dispersible polyurethane having a molecular weight of more than 40 2000 and carrying carbonyl groups in keto or aldehyde function, but also a further component carrying hydrazine or hydrazone groups or the polyurethane carries ~ CA 0221983~ 1997-11-20 BASFAKTIEN~3ESE~LSCHAFT o.Z,oo50/47497 hydrazine or hydrazone groups in addition to the carbonyl groups in keto or aldehyde function. In order to insert the structural element of the carbonyl groups into the polyurethane, it is recommended to use, in the preparation thereof, monomers such as dihydroxy acetone, the Michael adduct of diacetone acrylamide with diamine or alkanolamine or the Michael adduct of 2 mol of diacetone acrylamide with 2 mol of diamine.

A disadvantage of the dispersions that are prepared using dihydroxy acetone is however that the films that are prepared therewith are colored brown.

Another proposal made in this reference is to incorporate keto groups into the polyurethane by using monomers such as the Michael adduct of diacetone acrylamide with diethanolamine. These can be processed by the cold-curing process in a single-component system to form coatings having satisfactory 15 properties but are not suitable for use as one-component of two-component systems for the preparation of coatings having superior properties. Neither doesprocessing by the baking method yield coatings of high quality.

Furthermore, aqueous dispersions containing a water-dispersible polyurethane 20 containing carbonyl groups and a polyhydrazide are revealed in DE-A 3,837,519.
According- to this teaching, the carbonyl function is incorporated in the polyurethane by using, during preparation thereof, mono- or poly-alcohols containing carbonyl groups, eg monohydroxy alkyl ketones such as hydroxy-acetone, hydroxybenzaldehyde, acetoin, benzoin, adducts of diepoxides with 25 ketocarboxylic acid and also ketocarboxylate containing at least one hydroxylgroup. Another recommendation made in this paper is to use these dispersions as varnishes or printing inks.

These monomers cannot be used automatically, since problems relating to, say, 30 low reactivity, intrinsic color of the polymer or stability of the dispersion occur.

The two aforementioned classes of compounds suffer from another drawback, ie they are only useful for a very restricted number of cross-linking possibilities.

35 Furthermore, esters of pyruvic, acetacetic or levulinic acid with polyols areincluded under the keto monomers containing one or more alcoholic hydroxyl groups described in DE 3,837,519. An important drawback resulting from the use of these ester derivatives is their tendency to become hydrolyzed in the dispersion prepared therefrom. During storage, the free acid is gradually eliminated, as a 40 result of which the cross-linking efficiency declines. During the hydrolytic degradation of dispersions containing acetoacetic ester alcohol, gas formation CA 0221983~ 1997-11-20 BASFAKT1~16~FI I SCHAFT o.zooso/47497 takes place. Storage of these dispersions in sealed containers is consequently associated with a considerable potential hazard. The levulinate exhibits, in addition, reduced reactivity, since the ketocarbonyl group possesses no activating group in the immediate vicinity. The use of the pyruvate produces colored s polymers.

DE-A 4,406,547 describes cross-linkable polyurethanes that are functionalized with olefinic double bonds and CH-acidic groups and are present dispersed in water. For the preparation thereof, a hydroxyl-terminated, substantially linear and solvent-free polyurethane is caused to react with a low molecular weight ester.
Esterification produces polyurethanes containing terminal ~-functional ester groupings.

This process is not generally useful, since for example "harder" or branched-chain 15 polyurethanes exhibiting a high viscosity cannot be modified without the use of a solvent for viscosity reduction. Low-boiling solvents which would be capable of being removed from the dispersion by distillation, cannot be used, since the temperature that is required for the transesterification stage cannot be achieved. If the solvent is boils at a higher temperature, it is then no longer possible for it to be 20 removed from the dispersion.

Even when use is made of temperatures which are so high that a direct result is thermal damage to the polyurethane, the total reaction of all hydroxyl groups of the polyurethane cannot be guaranteed, as is also evident from the article "Novel 25 synthesis of low VOC polymeric dispersion and their application in waterbornecoatings" in the 21st Int. Conf. Organ. Coat. Sci. Technol. Athens, pp 55-68 (1995), particularly page 60, by B. Vogt-Birnbrich.

The dispersions produced by this process likewise have a high tendency to 30 become hydrolyzed and develop gas during storage.

Coatings comprising dispersions containing a polyurethane which is composed of the said hydroxycarbonyl compounds can still not give complete satisfaction as regards their mechanical properties and resistance to solvents. In addition, these 35 dispersions show a tendency toward coagulation.

The non-prepublished German patent application bearing the file number 19618675.7 describes aqueous dispersions containing a polyurethane which is likewise composed of alcohols having carbonyl groups in keto function. These alcohols ploposed therein differ from those used in the present invention in thenumber of alcohol groups present. Said reference concerns polyfunctional SFA~ I IE~. ;E ~ I ~CHAFT O.Z. ooso/47497 alcohols.

It is thus an object of the present invention to provide aqueous coating compositions having a high overall level of application properties, which do notexhibit the deficiencies of the prior art, and in the processing of which to form glossy heavy-duty coatings no or only relatively small amounts of volatile levelling auxiliaries need to be used. In particular, the coating compositions should be usable in as wide a range as possible, that is to say, the property level of thecoatings that is attainable therewith should not fall short of that of the prior art when using various processing methods.

Another object of the invention is to provide printing inks which do not exhibit the deficiencies of the prior art and which make it possible to produce, in particular, printed non-polar substrates to which the ink adheres permanently.

Accordingly, we have found the dispersions described above.

The dispersions contain a polyurethane (A), which is composed of compounds of the formula (I) - R1R2CH - ICl - CR3R4 - ICl - NR5R5 (I), O O
in which the substituents generally have the following meanings:

R1, R2, R3 independently denote hydrogen, C1-C24 alkyl or C8-C24 alkenyl R4 denotes hydrogen, 30 R5, R~ a) together form C4-C10 alkanediyl, preferably butane-1,4-diyl and pentane-1 ,5-diyl, b) each denotes C2-C10 alkyl, nnore preferably C2 and C3 alkyl or C5-C8 cycloalkyl, preferably cyclopentyl or cyclohexyl or C7-C20 aralkyl, preferably benzyl, c) each denotes a hydroxyl-terminated poly(C2-Ci alkylene oxide), preferably a radical of the formula lll - CH2 - CH - O-- (Ill), ~ n CA 0221983~ 1997-11-20 BASFAKTI~NGEsELL5cHA~ o.~.ooso/47497 in which R8 denotes hydrogen, methyl and/or ethyl and s n is an integer from 1 to 10 or d) one of the radicals R5 and R~ has the meaning stated under (a) to (c) and the other radical is hydrogen or a radical of the formula ll R1R2CH - C - CR3R4 - C - N - X (Il), ~s O O
in which X denotes C2-C8 alkanediyl and R7 has the same meaning as R~ or R8 with the exception of the radical of formula ll.

where 25 - the radicals Rs und R6 together carry one hydroxyl group attached to an aliphatic carbon atom and, optionally, - the radical R5 and/or R~ carries one or two hydroxyl groups bonded to an aromatic carbon atom or one nitrile, tertiary amino, carboxylic acid or sulfonic acid group optionally present in the form of their salts - the average functionality (F) of all structural components, based on the functionalities which occur during synthesis of the polyurethane, being from 1.5 to 2.2, preferably from 1.7 to 2.0, and more preferably from 1.8 to 1.95.

The person skilled in the polyurethane art is well aware of the fact that the molecular weight can be controlled by the choice of the average functionality ofthe starting materials which interreact in an addition reaction to form urethane or 40 urea groups, ie those containing isocyanate, alcohol, primary amine and secondary CA 0221983~ 1997-11-20 BASFAKTIENGEsELLscHAFT o.z.oo50/47497 amine groups. Since the compounds of the formula (I) are monofunctional with respect to the synthesis of the polymer chain of the polyurethane, it will generally be necessary to use not only the difunctional starting materials usually employed but also trifunctional compounds and compounds of higher functionality.
s The average functionality (F) is defined by the quotients F number of moles of all isocyanate groups and isocyanate-reactive groups number of moles of all structural components The functional groups taken into consideration for the calculation of F are not only isocyanate groups and alcohol groups attached to aliphatic carbon atoms but alsoother groups which react with isocyanates in an addition reaction and which react at a similar rate or even more rapidly than said alcohols, that is to say, for 15 example, primary amine and secondary amine groups. On account of their greater inertness, hydroxycarbonyl groups and hydroxyl groups bonded to an aromatic carbon atom are not taken into account however.

With regard to the desired density of cross linkage and the mechanical properties zO dependent thereon, the concentration of the carbonyl groups of the structuralelements in the polyurethane which are derived from the compounds of the formula (I) is made to be such that generally from 3 to 140, preferably from 6 to 100, more preferably from 10 to 90 mmol of these groups are present per 100 g ofpolyurethane.

The preparation of the aqueous dispersions of the invention usually takes place by 1. Preparation of a polyurethane by causing the reaction of a) polyvalent isocyanates containing from 4 to 30 carbon atoms, b) polyols, of which b1 ) from 10 to 100 mol, based on the total weight of the polyols(b), have a molecular weight of from 500 to 5000 and b2) from 0 to 90 mol, based on the total amount of the polyols (b), are difunctional and have a molecular weight of from 62 to 500 g/mol, c) compounds of the formula 1, .. CA 0221983S 1997-11-20 BASFAKTIENGEsE~Lsc~AFT o~oo50147497 d) optionally other polyvalent compounds containing reactive groups and differing from the monomers (b) and (c), said groups being alcoholic hydroxyl ~roups or primary or secondary amino groups and 6 e) monomers differing from monomers (a), (b), (c) and (d) and con-taining at least one isocyanate group or at least one isocyanate-reactive group and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, by which means the polyurethanes are rendered water-dispersible.
,0 Il. Dispersion of the polyurethane obtained in step I in water.

Suitable monomers (a) are the polyisocyanates usually employed in polyurethane chemistry.

Examples of particularly suitable monomers are diisocyanates X(NC0)2, where X
stands for an aliphatic hydrocarbon radical containing from 4 to 12 carbon atoms, a cycloaliphatic or aromatic hydrocarbon ra~ical containing from 6 to 15 carbon atoms or an araliphatic hydrocarbon radical containing from 7 to 15 carbon atoms.
20 Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylenediisocyanate, dodecamethylene diisocyanate, 1 ,4-diisocyanatocyclohexane, 1- iso-cyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane ( IPDI ), 2,2-bis-( 4-iso-cyanatocyclohexyl)propane, trimethylhexane diisocyanate, 1,4-diisocyanatoben-zene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenyl-25 methane, tetramethylxylylene diisocyanate (TMXDI), 2,4'-diisocyanatodiphenyl-methane, p-xylylene diisocyanate, the isomers of bis(4-isocyanatocyclohexyl)-methane such as the trans/trans, the cis/cis and the cis/trans isomers and also mixtures of these compounds.

30 Important mixtures of these isocyanates are particularly the mixtures of the respective structural isomers of diisocyanatotoluene and diisocyanatodiphenyl-methane; particularly suitable is a mixture of 80mol of 2,4'-diisocyanatotolueneand 20mol of 2,6-diisocyanatotoluene. Furthermore mixtures of aromatic iso-cyanates such as 2,4'-diisocyanatotoluene and/or 2,6-diisocyanatotoluene with 35 aliphatic or cycloaliphatic isocyanates such as hexamethylene diisocyanate or IPDI
are particularly advantageous, the prefer,ed component ratio of the aliphatic toaromatic isocyanates being from 4:1 to 1:4.

The compounds (a) used may also be isocyanates which carry not only free 40 isocyanate groups but also other hidden isocyanate groups, eg uretdione or CA 0221983~ 1997-11-20 BASFAKTIEN~EsEL~scHAFT o.z.oo50/47497 carbodilmide groups.

Optionally, isocyanates may be included which carry only one isocyanate group.
The concentration thereof is generally not more than 10 mol%, based on the totals molar content of the monomers. The monoisocyanates usually carry other functional groups such as olefinic group~ or carbonyl groups and serve to introduce functional groups into the polyurethane which enable dispersion or cross linkage or other polymer-like reactions of the polyurethane to take place. Suitable monomers for this purpose are monomers such as isopropenyl-a,o~-dimethylbenzyl isocyanate (TMi).

To increase the average functionality (F), use may be made of, eg, trivalent andtetravalent isocyanates. Such isocyanates are obtained, for example, by effecting interreaction of divalent isocyanates by converting a portion of their isocyanate 16 groups to allophanate, biuret or isocyanurate groups. Commercially available compounds are for example the isocyanurate or biuret of hexamethylene diisocyanate .

Other suitable polyisocyanates of higher functionality are eg polyisocyanates 21~ exhibiting urethane groups and based on ~,4- and/or ~,6-diisocyanatotoluene,isophorone diisocyanate or tetramethylene diisocyanate on the one hand and low molecular weight polyhydroxy compounds such as trimethylol propane on the other hand.

25 Suitable polyols as regards good film formation and elasticity are (b) mainly polyols of higher molecular weight, preferably diols (b1 ) having molecular weights of from approximately 500 to 5000, preferably from approximately 1000 to 3000 g/mole.

The polyols (b1 ) concerned are, in particular, polyester polyols described in, eg, 30 Ullmanns Encyklopaedie der technischen Chemie, 4th Edition, Vol. 19, pp 62 to65. Preferably use is made of polyester polyols obtained by the reaction of divalent alcohols with divalent carboxylic acids. Instead of the free poly(carboxylic acid)s, the corresponding poly(carboxylic anhydride)s or corresponding polycarboxylates of lower alcohols or mixtures thereof may be used for the preparation of the 35 polyester polyols. The poly(carboxylic acid)s can be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and be optionally substituted by, eg, halogen atoms and/or be unsaturated. I~xamples of sultable compounds are: suberlc acld, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endo-4t) methylene tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleicanhydride, fumaric acid, and dimeric fatty acids. Preferred are dicarboxylic acids of CA 0221983~ 1997-11-20 o.z.oo5~/47497 the general formula HOOC-(CH2)y-COOHI in which Y is an integer from 1 to 20, preferably an even number from 2 to 20, eg succinic acid, adipic acid, dodecanoic acid and sebacic acid.

s Suitable polyvalent alcohols are eg ethylene glycol, propane-1 ,2-diol, propane-1,3-diol, butane-1,3-diol, butene-1,4-diol, butyne-1,4-diol, pentane-1,5-diol, neo-pentyl glycol, bis(hydroxymethyl)cyclohexanes such as 1,4-bis(hydroxymethyl)-cyclohexane, 2-methylpropane-1,3-diol, methylpentane diols, also diethylene glycol, triethylene glycol, tetraethylene glycol, poly(ethylene glycol), dipropylene glycol, poly(propylene glycol), dibutylene glycol and poly(butylene glycol)s.
Preferred are neopentyl glycol and alcohols of the general formula HO-(CH2)X, inwhich x is an in integer from 1 to 20, preferably an even number from 2 to 20.
Examples of these are ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1 ,8-diol and dodecane-1,1 2-diol.

Furthermore, polycarbonate diols are also suitable, such as can be prepared by, say, the reaction of phosgene with an excess of the low molecular weight alcohols specified as structural components for the polyester polyols.

20 Also suitable are polyester diols based on lactones, these being homopolymers or mixed polymers of lactones, preferably addition products of lactones with suitable difunctional starting molecules, said addition products having terminal hydroxylgroups. Suitable lactones are preferably those derived from compounds of the general formula HO-(CH2)z~ in which z is an integer from 1 to 20. Examples are ~-25 caprolactone, ~-propiolactone, r-butyrolactone and/or methyl-~-caprolactone and mixtures thereof. Suitable starting components are eg the dihydric alcohols of low molecular weight specified above as structural com,oonen~s for the polyesterpolyols.The corresponding polymers of ~-caprolactone are particularly preferred. It is also possible to use lower polyester diols or polyether diols as starters for the 30 preparation of the lactone polymers. Instead of the polymers of lactones use may be made of the corresponding chemically equivalent polycondensates of hydroxy-carboxylic acids corresponding to the lactones.

The polyesterols can also be composed of minor amounts of mono- and/or poly-functional monomers.

Other suitable monomers (b1 ) are polyether diols. They can be obtained, in particular, by polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with itself, eg in the presence of 40 BF3, or by the addition of these compounds, optionally in admixture or successively, to starting components containing reactive hydrogen atoms, such as alcohols or . ~ CA 0221983S 1997-11-20 SFA~IIL,; .E IscHA~ o.z.oo50/47497 amines, eg water, ethylene glycol, propane-1,2-diol, propane-1,3-diol, 1,2-bis(4-hydroxydiphenyl)propane or aniline. Particularly preferred is polytetrahydrofuran having a molecular weight of from 240 to 5000, and preferably from 500 to 4500.

5 Also suitable are polyhydroxy olefins, preferably those containing 2 terminal hydroxyl groups, eg o~,~-dihydroxypolybutadiene, ol,~-dihydroxypolymethacrylate or o(,c.)-dihydroxypolyacrylate, as monomers (bl ). Such compounds are disclosed, for example, in EP-A 0,622,378. Other suitable polyols are polyacetals, polysiloxanes and alkyd resins.

The polyols can also be used as mixtures in any desired proportions.

The hardness and the modulus of elasticity of the polyurethanes can be raised when the polyols (b) used are not only the polyols (b1 ) but also diols (b2) of even lower molecular weight, ie having a molecular weight of from approximately 62 to500, preferably from 62 to 200 g/mole.

The monomers (b2) used are primarily the structural components of the short-chain alkane diols specified for the preparation of polyester polyols, where 20 neopentyl glycol and the unbranched diols having from 2 to 12 carbon atoms and an even namber of carbon atoms are preferred.

The concer,l,alion of of the polyols (b1), based on the total amount of polyols (b) is preferably from 10 to 100mol% and the concentration of the monomers (b2), 25 based on the total amount of the polyols (b) is preferably from 0 to 90mol%.
Particularly preferred is a ratio of the polyols (b1 ) to the monomers (b2) of from 0.2:1 to 5:1, and more preferably from 0.5:1 to 4:1.

Suitable components (c) are primarily compounds of the formula (I).
3~
The compounds of formula (I) can be obtained by causing a diketene of the formula ( IV) ~1~ R3 ( IV) 35R1~ ~R4 to react with an alkanolamine of the formula (V) R5 (V) 4tl H - N~

~ CA 0221983~ 1997-11-20 - BASFAKTIEN~EsE~Lsc~AFT o.z.o~so/47497 in an addition reaction.

In the diketenes of formula (IV) or the amines of formula (V) the radicals R1, R2, R3 and R4 or the radicals R5, R~ and R7, respectively, have the same meanings as 5 specified for the compound of formula (I).

It is particularly pre~elled to use a diketene in which the radicals R1, R2 and R3 denote hydrogen or one of the radicals R' or R2 denotes hydrogen and the other radical R1 or R2 and the radical R3 denote a linear, saturated, unsubstituted ,0 hexadecyl radical.

Particularly preferred alkanolamines are ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-cyclohexylethanolamine, N-tert-butyl-ethanolamine, leucinol, isoleucinol, valinol, prolinol, hydroxyethylaniline, 2-(hydroxy-methyl)piperidine, 3-(hydroxymethyl)piperidine, 2-(2-hydroxyethyl)piperidine, 2-amino-2-phenylethanol, 2-amino-1-phenylethanol, ephedrine, p-hydroxyephe-drine, norephedrine, adrenaline, noradrenaline, serine, isoserine, phenylserine, 1,2-diphenyl-2-aminoethanol, 3-amino-1 -propanol, 2-amino-1 -propanol, 2-amino-2-methyl-1 -propanol, isopr~panolamine,N-ethylisopropanolamine, 2-amino-3-phen-20 ylpropanol, 4-amino-1-butanol, 2-amino-1-butanol, 2-aminoisobutanol, neopent-anolamine, 2-amino-1-pentanol, 5-amino-1-pentanol, 2-ethyl-2-butyl-5-amino-pentanol, 6-amino-1-hexanol, 2-amino-1-hexanol, 2-(2-aminoethoxy)ethanol, 3-(aminomethyl)-3,5,5-trimethylcyclohexanol, 2-aminobenzylalcohol, 3-aminoben-zylalcohol, 2-amino-5-methylbenzylalcohol, 2-amino-3-methylbenzylalcohol, 3-25 amino-2-methylbenzylalcohol, 3-amino-4-methylbenzylalcohol,3-amino-6-meth-ylbenzylalcohol, 1-aminoethyl-4-hydroxybenzylalcohol, 2-(4-aminophenyl)ethan-ol, 2-(2-aminophenyl)ethanol, 1-(3-aminophenyl)ethanol, serine, homoserine, threonine, ethanolaminoacetic acid, 4-amino-3-hydroxybutyric acid, N-( 2-hydroxy-ethyl)-glycinnitrile, 4-(2-hydroxyethyl)piperazineand 1 -amino-4-(2-hydroxyethyl)-30 piperazine, 2-hydrazinoethanol or diaminomonools, such as N-(2-aminoethyl)-ethanolamine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, 1,3-diamino-2-propanol may also be used~

P~efel,ed adducts of formula I are those containing the diketene in which the 35 radicals R1, R2 and R3 each denote hydrogen~ Particularly preferred is CH3C( = O)-CH2-C(C = O)-NH-CH2-CH2-OH~

The preparation of the compounds of formula (I) can be carried out, for example,in the manner described for the acetoacetamide derivatives in the patent 40 specifications DE 1,142,859 and GB 715,896.

CA 0221983~ 1997-11-20 BASFAKTIENoEsELLscHAFT o.z.~oso/47497 The monomers (d) which differ from the components (b) and diols (c) generally serve to increase the average functionality (F). They are generally more than dihydric non-aromatic alcohols, amines containing two or more primary and/or secondary amino groups and also compounds which carry in addition to one or 5 more alcoholic hydroxyl groups one or more primary and/or secondary amino groups.

Alcohols which are more than dihydric are eg trimethylol propane, pentaerythritol glycerol or sugar and their ethoxylation products.

Polyamines containing 2 or more primary and/or secondary amino groups are primarily used when the chain growth or cross linkage should take place in the presence of water, since amines usually react more quickly than alcohols or water with isocyanates. This is frequently necessary when aqueous dispersions of branched-chain polyurethanes or polyurethanes of high molecular weight are desired. In such cases the procedure adopted is to prepare prepolymers containing isocyanate groups and then to rapidly disperse the same in water and subsequently increase the chain length or effect cross linkage by the addition of compounds containing a plurality of amino groups reactive with isocyanate.

Suitable amines for this purpose are generally polyfunctional amines in the molecular weight range of from 32 to 500 g/mole, preferably from 60 to 300 g/mole, which contain at least two primary, two secondary or one primary andone secondary amino group. Examples thereof are diamines such as diamino-25 ethane, diaminopropanes, diaminobutanes, diaminohexanes, piperazine, 2,~-dimethylpiperazine, amino-3-aminomethyl-3,5,5-trimethylcyclohexane ( isophor-onediamine, IPDA), 4,4-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylene triamine, triethylene tetramine or 1,8-diamino-4-aminomethyloctane.

The amines can also be used in blocked form, ~g in the form of the correspondingketimines (cf eg CA 1,1 2g,1 28), ketazines (cf eg the US-A 4,269,748) or amine salts (cf US-A 4,292,226). Oxazolidines such as are used, for example, in US-A
4,1 92,937 are also hidden polyamines which can be used for the preparation of 35 the polyurethanes of the invention to effect chain growth of the prepolymers.When using such hidden polyamines they are generally mixed with the prepolymers in the absence of water and this mixture is subsequently mixed with the dispersant water or a portion of the dispersant water so that the co~esponding polyamines are liberated hydrolytically.

CA 022l983~ l997-ll-20 BASFA~ I e~AFT oz.~o50/47497 The polyurethanes preferably contain no polyamine or from 1 to 10, more preferably from 1.5 to 5 mol%, based on the total amount of the components (b), (c) and (d), of a polyamine having at least 2 amino groups which are reactive with isocyanates, as monomers (d).
s Furthermore, minor amounts of monoalcohols can be used to effect chain stoppage, ie preferably in amounts of less as 10mol%, based on components (b) and (d) The function thereof is generally similar to that of the monoisocyanate, ie they mainly serve to effect functionalization of the polyurethane having free-radically polymerizable C =C double bonds.

In order to make the polyurethanes water-dispersible, the polyurethanes are not only composed of the components (a), (b), (c) and (d) but also of monomers (e) differing from the components (a), (b?, (c) and (d) and carrying at least one 15 isocyanate group or at least one isocyanate-reactive group and in addition at least one hydrophilic group or a group capable of being converted to hydrophilic groups.
Below, the term "hydrophilic groups or potentially hydrophilic groups" is abbreviated to "(potel~lially) hydrophilic groups". The (potentially) hydrophilic groups react with isocyanates much more slowly than the functional groups of the20 monomers which are used for the synthesis of the main polymer chain.

The concentration of the components containing (potentially) hydrophilic groups based on the total amount of the components (a), (b), (c), (d) and (e) is generally such that the molar magnitude of the (potentially) hydrophilic groups, based on the 25 weight of all monomers (a) to (e), is from 30 to 1000, preferably from 50 to 500 and more preferably from 80 to 400 mmol/kg.

The (potentially) hydrophilic groups can be non-ionic or preferably (potentially) ionic hydrophilic groups.

Particularly suitable non-ionic hydrophilic groups are poly(ethylene glycol ether)s comprising preferably from 5 to 100, more preferably from 10 to 80, recurring ethylene oxide units. The concentration of polyethylene oxide units is generallyfrom 0 to 10, preferably from 0 to 6wt%, based on the weight of all monomers (a)35 to(e).

Preferred monomers containing non-ionic hydrophilic groups are the reaction products of a poly(ethylene glycol) and a diisocyanate carrying a terminal etherified poly(ethylene glycol) radical. Such diisocyanates and processes for the 40 preparation thereof are described in the patent specifications US 3,905,929 and 1ff CA 0221983~ 1997-11-20 BASFAK~IE~EsELLscHAFT o.zooso/47497 '' US 3,920,598.

Ionic hydrophilic groups are primarily anionic groups such as the sulfonate, carboxylate and phosphate groups in the form of their alkali metal or ammonium s salts and also cationic groups such as ammonium groups, particularly protonized tertiary amino groups or quaternary ammonium groups.

Potentially ionic hydrophilic groups are primarily those which can be converted by simple neutralisation, hydrolysis or quaternizing reactions to the aforementioned .0 ionic hydrophilic groups, that is to say, for example, carboxylic acid groups, anhydride groups or tertiary amino groups.

(Potentially) ionic monomers (e) are described in detail in, eg, Ullmanns Encyklopaedie der technischen Chemie, 4th Edition, Vol. 19, pp 31 1-313 and for 15 example in DE-A 1,495,745.

(Potentially) cationic monomers (e) are primarily monomers containing tertiary amino groups of special practical significance, for example: tris(hydroxyalkyl)-amines, N,N-bis(hydroxyalkyl)alkylamine, N-hydroxyalkyldialkylamine, Tris(amino-20 alkyl)amines, N,N-bis(aminoalkyl)alkylamines, N-aminoalkyldialkylamines, where the alkyl radicals and alkanediyl units in these tertiary amines independently contain from 2 to 6 carbon atoms. Also suitable are polyethers containing tertiary nitrogen atoms and preferably containing two terminal hydroxyl groups, such as can be prepared, eg, by alkoxylation of two amines having hydrogen atoms 25 attached to amine nitrogen, eg methylamine, aniline, or N,N-dimethylhydrazine, in conventional manner. Such polyethers generally have a molecular weight between 500 and 6000 g/mole.

These tertiary amines are converted to the ammonium salts either with acids, 30 preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids or strong organic acids or by reaction with suitable quaternizing agents such as C1 to C~ alkyl halides, eg bromides or chlorides.

Suitable monomers containing (potentially) anionic groups are usually aliphatic,35 cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids carrying at least one alcoholic hydroxyl group or at least one primary or secondary aminogroup. Preferred are dihydroxyalkylcarboxylic acids, primarily containing from 3 to 10 carbon atoms, such as are also described in US-A 3,412,054. We particularly prefer compounds of the general formula Vl CA 0221983~ 1997-11-20 BASFAKTIENoEsEL-scHAFT o.z.ooso/47497 COOH
HO - R~- C - R~- OH (Vl) RC

5 in which Ra and Rb stand for a C1 to C4 alkanediyl unit and Rc stands for a C1 to C4 alkyl unit, especially dimethylolpropionic acid (DMPA).

Also suitable are corresponding dihydroxysulfonic acids and dihydroxyphosphonic acids such as 2,3-dihydroxypropanephosphonic acid.
.0 Also suitable are dihydroxyl compounds having a molecular weight of more than 500 to 10000g/mole and containing at least 2 carboxylate groups, which are disclosed in DE-A 3,911,827. They can be prepared by the reaction of dihydroxyl compounds with tetraoic dianhydrides such as pyromellitic dianhydride or cyclopentanetetroic dianhydride in a molar ratio of from 2:1 to 1 05:1, in a polyaddition reaction. Particularly suitable dihydroxyl compounds are the mono-mers (b2) mentioned as chain extenders and also the polyols (b1).

Suitable monomers (e) containing isocyanate-reactive amino groups are amino-20 carboxylic- acids such as Iysine, ~-alanine, the adducts, mentioned in DE-A

2,034,479, of aliphatic diprimary diamines with ~ unsaturated carboxylic acids such as N-(2-aminoethyl)-2-aminoethanecarboxylic acid and also the correspond-ing N-aminoalkylaminoalkylcarboxylic acids, where the alkanediyl units contain from 2 to 6 carbon atoms.

If monomers containing potentially ionic groups are used, they can be converted to the ionic form before or during, but preferably after, the isocyanate polyaddition reaction, since the ionic monomers in the reaction mixture frequently dissolve only with difficulty. We particularly prefer that the carboxylate groups be present in the 30 form of their salts with an alkali ion or an ammonium ion as counterion.

Effective amounts of compounds which are structurally related to those of the formula (I) and which differ from those of formula (I) only in that the radicals R
carry not just 1 but from 2 to 5 hydroxyl groups attached to aliphatic carbon atoms, 35 are used for the preparation of the polyurethanes (A) of the invention not ineffective amounts and are preferably not used at all. These compounds structurally related to those of formula (I) are described in the non-prepublished German application bearing the file number 19618675.7.

40 Normally are the components (a), (b), (c), (d) and (e) and also the respective CA 0221983~ 1997-11-20 FAKTIENGEsELLscHAFT o.z.oo50/47497 molar amounts thereof are selected such that the ratio of A to B where A) is the molar concentration of isocyanate groups and B) is the sum of the molar concentration of the hydroxyl groups and the molar concentration of the functional groups which can react with isocyanate in an addition reaction.

is from 0.5:1 to 2:1, preferably from 0.8:1 to 1.5:1, and more preferably from 0.9:1 to 1.2:1. Most preferably the ratio A:B is as near to 1:1 as possible.

Not only the components (a), (b), (c), (d) and (e) but also monomers containing only one reactive group are generally used in amounts of up to 15 mol%, preferably up to 8 mol%, based on the total amount the components (a), (b), (c), (d) and (e).

The polyaddition of the components (a) to (e) generally takes place at reaction temperatures of from 20 to 180 ~C preferably from 50 to 150~C under standard pressure or under autogenous pressure.

20 The necessary reaction times may range from a few minutes to some hours. It is known in the art of polyurethane chemistry that the reaction time is influenced by a number of parameters such as temperature, concentration of the monomers and reactivity of the monomers.

25 In order to accelerate the reaction of the diisocyanates, conventional catalysts, such as dibutyltin dilaurate, tin(ll) octoate or diazabicyclo-(2,2,2)-octane, can be used.

Suitable polymerizing equipment comprises stirred boilers, particularly when 30 solvents are used to lower the viscosity and provisions are made for good heat dissipation.

If the reaction is to be carried out in substance, extruders are particularly suitable by reason of the high viscosities usually encountered and the usually very brief3s reaction times, especially self-cleaning multiscrew extruders.

The dispersions are usually prepared by one of the following processes:

Using the "acetone process", an anionic polyurethane is prepared from the 40 components (a) to (e) in a water-miscible solvent boiling under standard pressure below 100~C. Water is added until a dispersion forms in which water is the - CA 0221983~ 1997-11-20 SFAKTIEN~EsEL~scHAFT o.z.ooso/474~7 coherent phase.

The "prepolymers mix process" differs from the acetone process in that there is first of all formed, instead of a completely reacted (potentially) anionic s polyurethane, a prepolymer carrying isocyanate groups. The components (a) to (d) used are in this case dimensioned such that the defined ratio A:B is greater than 1.0 to 3 and is preferably from 1.05 to 1.5. The prepolymer is first of all dispersed in water and subsequently cross-linked by reaction of the isocyanate groups withamines carrying more than 2 isocyanate-reactive amino groups or chain-extended with amines carrying 2 isocyanate-reactive amino groups. Chain growth takes place even when no amine is added. In this case isocyanate groups are hydrolyzedto amine groups which react with those isocyanate groups which still remain in the prepolymers to cause chain growth.

15 If a solvent has been used in the preparation of the polyurethane, the major portion of the solvent is removed from the dispersion, for example by distillation underreduced pressure. Preferably, the dispersions show a solvent concentration of less than 10 wt% and are more preferably free from solvents.

20 The dispersions generally have a solids concentration of from 10 to 75, preferably from 20 to 65wt% and a viscosity of from 10 to 500 m-Pas (measured at a temperature of 20 ~C and a shearing rate of 250 s~

The aqueous dispersions of the invention are usually virtually free from polyvalent 25 metal ions.

Hydrophobic auxiliaries which are possibly difficult to distribute homogeneously in the finished dispersion, such as phenol condensation resins of aldehydes and phenol or phenol derivatives or epoxy resins and other polymers specified, eg, in 30 DE-A 3,903,538, 4,309,079 and 4,024,567, and which are used in polyurethane dispersions for example as adhesion promotors, may be added to the polyurethane or the prepolymers before dispersion takes place by the methods that are described in the two specifications mentioned above. Suitable hydrophobic auxiliaries are specified, for example, in DE-A 3,903,538, 4,024,567 and 35 4,309,079.

In one variant of the present invention the polyurethane dispersions of the invention are modified with free-radically polymerizable monomers containing a C=C double bond and not exhibiting any isocyanate groups or isocyanate-reactive groups (monomers f). In this case said monomers are primarily those usually employed in the preparation of emulsion polymers.

CA 022l983~ l997-ll-20 BASFAKTIENoEsE~LscHAFT o.z.ooso/47497 Suitable monomers tf) are, eg, the C1 to C~ alkyl esters of (meth)acrylic acid and also lauryl acrylate and butane diol diacrylate or compounds containing carbonylgroups, such as eg methylvinyl ketone, (meth)acrolein, crotonaldehyde, diacetone(meth)acrylamide, diacetone (meth)acrylate.
s Other monomers are eg vinyl esters of carboxylic acids containing up to 20 carbon atoms such as vinyl laurate, vinyl stearate, vinyl acetate and vinyl propionate, vinyl aromatic compounds containing up to 20 carbon atoms such as styrene and viny toluene, ethylenically unsaturated nitriles such as acrylonitrile and methacrylo-nitrile, ethylenically unsaturated amides such as acrylamide and methacrylamide,vinyl halides such as vinyl chloride and vinylidene chloride and aliphatic hydrocarbons containing from 2 to 8 carbon atoms and having 1 or 2 C=C double bonds, such as butadiene and ethylene.

5 The monomer (f) may be added during the synthesis of the polyurethane (A), prior to dispersion of the polyurethane (A), or it can be added to the aqueous dispersion containing the polyurethane (A), and subjected to free radical polymerization byconventional methods.For this purpose radical forming polymerization initiators are added to the mixture of the polyurethane dispersion and the monomer (f). Further-20 more, the monomer (f) can be metered as a feed to a polyurethane dispersioncontaining initiator.

If it is desired to cause grafting of the polymer formed from the monomer (f) to the polyurethane, it is recommendable to additionally use, during synthesis of the 25 polyurethane, monomers containing a free-radically polymerizable C=C double bond.

In order to cause cross linkage of the polyurethane (A), there is usually added to the aqueous dispersion a cross-linking agent (b) which exhibits functional 30 substituents which react with the structural units derived from compounds of the formula (I), in an addition or condensation reaction. Such cross-linking agents (b) are for example compounds containing at least one aldehyde group or at least 2 functional substituents, selected from the group consisting of: primary amino group, secondary amino group, hydrazine group, hydrazide group, aminooxy group, 35 isocyanate group or blocked isocyanate group.

Suitable polyamines are eg non-polymeric amines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, propylenediamine, butylenediamine, 1,6-hexanediamine, 1,1 2-dodecanediamine, cyclohexylenediamine, piperazine, 2-40 methylpiperazine, isophoronediamine, phenylenediamine, tolylenediamine, xylylene-CA 0221983~ 1997-11-20 BASFAKTIEN~EsELLscHAFT o.z.ooso/47497 diamine, 4,4-diaminodiphenylmethane, menthanediamine and m-xylenediamine.
The reactive amino compound can also be a polymer such as an acrylic resin, a polyester resin or a polyurethane resin containing amino groups, a poly(propylene oxide) containing amino groups (jeffamines), or a polyethyleneimine.
s These amines can be used in blocked form if desired, that is to say in the form of their aldimines or ketimines. These blocked amines are well known and are described, for example, by K. J. Kim and R. C. Williams in "Proceedings of the annual Waterborne and Higher Solids Symposium, New Orleans, 57, (1993)" and by B. Vogt-Birnbrich in "Proceedings of the 21 st International Conference in Organic Coatings, Athens, 55, (1995)" and also in EP-A 552,469 and EP-A
584,818. Use is preferably made of amines blocked with aromatic aldehydes such as benzaldehyde.

Suitable polyhydrazides are eg dicarboxylic dihydrazides as described, for example, in EP-A 442,652, page 11, line 52 to page 12, line 1. These are preferably derived from dicarboxylic acids, of which the polyesterdiols which can be used as component (b1) are also composed. Furthermore use can also be made of the corresponding polyhydrazone derivatives, eg those derived from acetone or ZO butanone.

Other suitable polyhydrazides having improved water solubility are described, eg, in EP-A 629,657.

25 Furthermore, suitable cross-linking agents (b) are polyisocyanates having a cross-linking action caused by transimination. Such compounds are described, for example, in DE-A 4,121,946.

Cross-linking agents containing aminooxy groups, which may also be used in the 30 form of their salts, are disclosed, ~g, in EP-A 516,074 or DE-A 4,219,384.

Another cross-linking method consists in the addition of aldehydes containing one or more aldehyde groups, which may be protected if desired, to the dispersion ofthe invention.

Suitable monoaldehydes are eg compounds of the formula X-R9-CHO, in which R9 denotes a C1 to C~ alkanediyl radical and X is a hydrogen atom or a hydroxy-carbonyl radical. Preferred aldehydes are formaldehyde, acetaldehyde and benzaldehyde.

Suitable polyfunctional aldehydes are low molecular weight compounds, particular-CA 0221983~ 1997-11-20 ~SFAKTIENGEsE~LscHAFT o.z~o50/47497 Iy aliphatic aldehydes of the formula OCH-(CH2)n-CHO, in which n is an integer from 0 to 8, preferably from 0 to 4, such as glyoxal or glutaric dialdehyde.

It is also possible to use oligomers, polymers or copolymers of ethylenically s unsaturated, free-radically polymerizable aldehydes as cross-linking component.
Suitable ethylenically unsaturated, free-radically polymerizable aldehydes are eg acrolein, methacrolein, formylstyrene and hydroxymethylfurfuryl (meth)acrylate.
Such cross-linking components can, if they are not sufficiently soluble, be dispersed in the aqueous phase of the dispersion and take part in film formationwhen the dispersion is used as binding agent. Oligomers or polymeric cross-linking compone,lls of this kind having a molecular weight of from 1000 to 500,000 (weight average) are preferred.

By protected aldehyde groups we mean corresponding derivatives having a 5 comparable reactivity to that of the free aldehyde groups themselves. Acetals,mercaptals and mercaptols, dioxolanes and dithiolanes are for example suitable.
Acetal or dioxolane groups which have been formed in the reaction of aldehyde groups with alkanols having from 1 to 4 carbon atoms in the alkyl radical or with alkanediols containing 2 or 3 carbon atoms in the alkylene are preferred.

Examples - of unsaturated monomers having protected aldehyde functions are diethoxypropyl acrylate and diethoxypropyl methacrylate and (meth)acryloyloxy-propyl-1 ,3-dioxolan .

2s Other suitable aldehyde derivatives are aldimine compounds which have been prepared by the reaction of an optionally substituted aromatic or heteroaromaticaldehyde with an optionally polyfunctional primary amine. These compounds are well known and are described, eg, in EP 552,469 A3 or in US-P 5,451,653.

30 Cross linkage can also take place via Michael acceptors. Suitable Michael acceptors are well known compounds described in DE-A 4,237,492.

Generally the cross linkage is carried out by Michael addition in the presence of a catalyst. Suitable catalysts are Lewis bases or Broenstedt bases, such as are 35 described in DE-A 4,237,492.

The amounts of components (A) and (B) are preferably such that the molar ratio of the carbonyl groups of the structural elements derived from the compounds of theformula (I) to the functional substituents of the compounds (B) is from 0.1:1 to1 0 :1, preferably from 1 .5 :1 to 0 .5 :1 .

CA 0221983~ 1997-11-20 BASFAKTIENoEsEL~scHAFT o.z.o~so/47497 Other suitable cross-linking agents (B) are aminoplastic resins, eg melamine/form-aldehyde condensates such as are described by D.H. Solomon in The Chemistry of Organic Filmpolymers, pp 235 et seq, John Wiley & Sons, New York, 1967. These are preferably melamine/formaldehyde condensation resins having a molecular 5 weight of from 20 to 1000 and more preferably they are the partially or completely etherified derivatives thereof. The degree of etherification is preferably at least 45 % based on the maximum possible etherification. The melamine/formaldehyde condensates are etherified with monoalcohols of from 1 to 4 carbon atoms, such as methanol, ethanol, propanol and preferably butanol, and/or monoethers of diols containing a total of from 2 to 7 carbon atoms.

The melamine/formaldehyde condensates can however be partially replaced, if desired, by other cross-linking aminoplastics, such as are descrtibed in eg '~ethoden der organischen Chemie" (Houben-Weyl), Vol. 14/2, Part 2, 4th Edition,15 Georg Thieme Verlag, Stuttgart 1963, pp 319 et seq.

Other cross-linking possibilities are achievable using polyisocyanates. Suitableisocyanate compounds are particularly the well known commercially available "highsolid isocyanates", hydrophilized and/or blocked isocyanates (cf DE-A
20 4216536?.

Suitable isocyanates are the isocyanates used for the synthesis of the polyurethane and specified above as monomers (a). Of these, particularly the polyvalent iso-cyanates containing more than 2 isocyanate groups are preferred.

Suitable blocking agents for the isocyanates are for example alcohols and oximes, eg acetone oxime or methylethylketone oxime.

Cross-linking agents (B) can furthermore be polymeric resins carrying oxime-30 blocked isocyanate groups as described in DE-A 4,237,030, DE-A 3,345,448, WO
93/01245 and in US Patent 5,358,997.

Cross linkage of the polyurethanes (A) which are present in the aqueous dispersion of the invention, with a polyisocyanate usually takes place in the presence of a35 basic catalyst, eg a tertiary alkylamine.

With the exception of the non-blocked isocyanates and the aldimines, the dispersions of the invention are generally blended at any desired time prior to treatment with the cross-linking agent. It is equally possible to add the cross-40 linking agents to the polyurethane (A) prior to dispersion thereof in water, if CA 0221983~ 1997-11-20 BASFA~".,: ,E l~:cHAFT oz.oQ50/47497 desired.

The dispersions of the invention may also contain other resins that are emulsifiabie or dispersible in water, such as polymer resins, polyurethane resins, polyester s resins, epoxide resins or alkyd resins and also commercially available auxiliaries and additives such as foaming agents, defoaming agents, emulsifiers, thickeners,levelling agents and thixotropic agents, and colorants such as dyes and pigments.

Dispersions of the invention which contain, as cross-linking agents (B), a 10 compound containing isocyanate groups blocked with aldehyde, primary or secondary amino, hydrazine, aminoxy, hydrazide or ketoxime groups are referred to as single-component systems, since they can be processed within an arbitrary period of time following the preparation thereof.

Dispersions of the invention, to which cross-linkings agent (B) have been added which comprise a compound containing non-blocked isocyanate groups, are referred to as two-component systems, since on account of the restricted period of time in which the prepared mixture may be processed (ca 8 hours), mixing is usually carried out by the user of the dispersions.

The coating compositions prepared in this way are generally applied to the workpiece to be coated, by any of the methods conventionally used in the paints and coating compositions industry, that is to say, for example, by roller-coating, spraying, brush-coating, pouring or dip-coating.

Subsequent drying or final curing of the coating composition can take place bothby cold curing (ie by drying at temperatures of from 0 to 80 ~C, preferably at room temperature) or by the so-called baking methods (ie by drying at temperatures usually of from 80 to 280 ~C).

Suitable for cold curing are primarily cross-linking agents containing aldehyde,aldimine, primary or secondary amino, hydrazine, aminoxy or hydrazide groups.

It is suspected that the polyaddition or polycondensation reaction which causes 35 cross linkage does not take place in these systems until a large portion of the water has evaporated. The coating compositions involve therefore a single-component system comprising binding agent and cross-linking agent.

Cold curing may also be carried out in the presence of cross-linking agents (B) 40 containing free isocyanate groups. When using this processing method the dispersion of the invention should be applied to the workpiece not later than about CA 0221983~ 1997-11-20 SFAKTIENGEsELLscHAFT o.z.ooso/47497 8 hours foliowing mixing with the cross-iinking agent.

When use is made of (hetero)aromatic cross-linking agents (B) containing aldimine groups it is also possible to carry out cold curing. The shelf life of the dispersions of the invention ranges in such cases from one hour to several weeks depending on their composition.

When it is desired to process the coating composition following baking, suitablecross-linkings agent are particularly the aforementioned aminoplastic resins, blocked and non-blocked polyisocyanates and the Michael acceptors.

A certain degree of cross linkage of the polyurethane takes place under the conditions of the stove enamelling process even when no cross-linking agent is present. This is particularly the case when the cross linkage takes place in thepresence of the Lewis or Broenstedt bases described in DE-A 4,237,492, such as tertiary amines, eg 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

The coating compositions of the invention are particularly suitable for painting onto wood, metal, plastics materials, for coating paper, leather, textiles, and for the preparation of shaped articles and printing inks and for use as adhesives.

The dispersions of the invention are distinguished by the fact that even when no or only relatively small amounts of levelling agents are contained therein, they can be processed to give high-grade coatings.

Furthermore, the dispersions of the invention can be processed either as single-component or two-component systems by the cold-curing method or the baking method. This is advantageous for users who work with different methods selected from these 4 processing variants, because they will only need to stock up a small 30 number of polyurethane dispersions for the various processing methods.

On the other hand aqueous dispersions which contain the polyurethane (A) are highly suitable for the preparation of printing inks.

These printing inks preferably have the following composition:

( I ) from 1 5 to 30 wt-% of a binding agent, substantially consi~ling of the polyurethane (A) and the cross-linking agent (B) 40 (Il) from 7 to 15wt% of a pigment CA 0221983~ 1997-11-20 SFAKTIENGEsELLscHA~ o2.ooso/47497 ., (Ill) from 2 to 5wt% of an alcohol suitable for use as solvent ( IV) from 4.5 to 10 wt% of conventional additives s (V) from 45 to 70 wt% of water.

The cross-linking agents (B) are preferably the polyhydrazides described in detail above, which are used in the proportions specified above.

The conventional additives are auxiliaries and additives, such as are generally used in printing inks, that is to sayl for example, waxes, foam depressants, dispersing and wetting agents and also microcides.

Otherwise the components (ii) to (v) used in the printing inks are those generally 15 used in printing inks as disclosed, for example, in Ullmanns Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A22; 1993 VCH Publishers, Inc.; pp. 143 to 155.

These printing inks are particularly suitable for printing plastics films such as 20 polyethylene or polypropylene ~ilms which have a surface tension of from 30 to 50, preferably from 35 to 40, more preferably of from 37 to 39 mNtm (measured with water at a temperature of 23 ~C). Printing can be effected by conventional processes (cf loc cit. pp 1 45 and 1 46 ) .

25 Plastics films having such surface tensions are commercially available films which have been corona-treated.

These printing inks have, in association with said recommended substrates, an advantageous wetting action. The printed films are resistant to normal mechanical 30 stresses and solvents.

Abbreviations:

ADDH adipic dihydrazide IPDI Vestanat (~) IPDI sold by Huels / isophorone diisocyanate MHAA N-(2-hydroxyethyl)acetoacetamide.

40 MEK methyl ethyl ketone CA 0221983~ 1997-11-20 BASFAKTIENGEsELLscHAFT oz.o~so/47497 , .
TMP trimethylol propane parts parts by weight s mw molecular weight ok in order Examples Dispersion 1 400 Parts of a polyester of adipic acid, isophthalic acid and hexane-1,6-diol ofmw 1000 (molar ratio of the acids 1:1), 116.2 parts of MHAA (sold by LONZA), 40.2 parts of DMPA, 36 parts of butane-1,4-diol and 452.4 parts of IPDI were caused to react at g0 ~C in 250 parts of MEK. After 1 h, 33.6 parts of TMP were added and the reaction was continued for 3 h at 90 ~C. Following the addition of500 parts of acetone the isocyanate concentration was 0.92 % (theory 0.76 ). 30.4 parts of triethylamine, 1900 parts of water and 8.8 parts of diethylenetriamine 20 were successively added to the pale yellow, transparent prepolymer solution to form a milky dispersion. The solvents were removed. The solids concentration was34.9%. pH 7.6. Following storage of the dispersion for three months at room temperature the properties ~ere virtually unchanged.

25 Dispersion 1 a A mixture of 100 parts of dispersion 1, 2.77 parts of adipic dihydrazide and 20.8 parts of water; stable dispersion.

30 Comparison Dispersion 1 Comparison Dispersion 1 was prepared in a similar manner to Dispersion 1 except that instead of MHAA, 92.9 parts of diacetone/alcohol were used. 3 hours after the addition of TMP the NCO value was 2.65% (theory 1.03 %); after a further two 35 hours the NCO value was still 2.43 %.

Comparison Dispersion 1 a Comparison Dispersion 1a was prepared by a variation of the process for the preparation of Comparison Dispersion 1. Diacetone/alcohol and IPDI were first o~

- CA 0221983~ 1997-11-20 BASF~,~". E 15cHAFT o.z.oo50/47497 all caused to react alone at 90~C. After 2h there were added the polyester, hexane-1,6-diol, DMPA and MEK. After a further hour there was added TMP. 3 h after the addition of TMP the NCO concentration was 1.11 %. The batch was diluted with acetone and to the solution there were successively added s triethylamine, water and diethylenetriamine to form a milky dispersion. The solvents were removed. The solids concentration was 30.8 %. pH 8.3.

After about one week's storage at room temperature the dispersion had separated into solid material and serum. In the plastics container in which the dispersion had been stored there was superatmospheric pressure.

Dispersion 2 Dispersion 2 was prepared in a similar manner to dispersion 1 using the following constituents: 400 parts of polyester, 53.7 parts of DMPA,22.5 parts of butane-1,4-diol, 116.1 parts of MHAA, 441.3 parts of IPDI, 33.6 parts of TMP, 40.5 parts oftriethylamine and 8.8 parts of diethylenetriamine. There was formed a clear, slightly yellow dispersion. The solids concentration was 33.4 %. pH 8.3.

20 Comparison Dispersion 2 Comparisol1 Dispersion 2 was prepared in a similar manner to Dispersion 2 exceptthat instead of MHAA, 70.5 parts of 4-hydroxy-2-butanone were used. During the course of prepolymer synthesis the solution turned to an intense brown to black 25 color.

Dispersion 3 Dispersion 3 was prepared in a similar manner to dispersion 1 using the following 30 constituents: 400 parts of a polyester of adipic acid, isophthalic acid and hexane-1,6-diol having a mw of 1000 (molar ratio of the acids 1 :1), 58.1 parts of MHAA(sold by Lonza), 46.44 parts of hydroxyethyl acrylate, 40.24 parts of DMPA, 36.1parts of butane-1,4-diol, 42.4 parts of IPDI, 33.6 parts of TMP, 30.4 parts of triethylamine and 8.8 parts of diethylenetriamine. There was formed an opaque 35 dispersion. The solids concentration was 3.4 %. pH 7.9.

Test results Solvent required for disper~ion 1 a: 0 ~0 BASFA~ ... q~ 'CCHAFT o.z.ooso/47497 Pendulum Impact Test Example 0.5h 1 h 7h 1 d 7d Dispersion 1a 34 45 67 71 110 Alcohol Plasticizer and Water Vapor Tests (0 to 5; 0 = best mark) Example Alcohol Plastici~er Watervapor ~çd visually) (assçssed visually) i" ", l~liate!y/ 1 h/ 1 d il "" ,e.l;ately/ 1 h/ 1 dil "" ~e~l;dlely/ 1 h/ 1 d Dispersion la4/2-3/0-1 2-3/2-3/0-1 2-3/2-3/1 Gloss Test Dispersion 1 a: 79 %
~5 Tests on coatings prepared using Dispersion 3 BakingGloss Squ~re-cut Pendulum Acetone 28% H S04 385- H SO4 Temp. Adlesion ImrJact Test Tçs2t ~ es~
(~sessPd ~est rest 4h/60~C 24h/RT
(~C)vlsually) (C -5~) (seconds) (rs) (0-5*) ( ~-5*) 30-60 ok 2-3 102 4 4 0 30-80 ok 2 1 15 3 4 0 30-100 ok 2-3 112 3 4 0 30--120 ok 0--1 122 5 4 0 30--140 ok 0--1 134 10 2 0 30-160 ok 0--1 153 45 0 0 * school m~lhill!J system, (0 to 5; 0=best mark) The tests were carried out in the following manner.

Solvent required The dispersions were placed on glass plates so as to have a dry layer thickness of about 25~1m, and solvent was added in an amount such as is necessary is to 3s obtain a faultless film surface on drying. The necessary minimum amount to achieve this end is given in wt%.

CA 0221983~ 1997-11-20 BASFA~ ICCHAFT o.z.ooso/47497 Surface Hardness The surface hardness (pendulum impact hardness) was determined as specified in DIN 53157 using a king tool. The number of impacts is given in the tables. In 5 the case of Dispersion 1a, the tests were carried out at various times following application of the dispersion, as specified in the table, whilst in the case of Dispersion 3 the test was carried out immediately after baking.

Water vapor, alcohol and plasticizer tests .0 These tests were carried out according to DIN 68860B on double-layer coats of varnish on wood. The visual assessment took place immediately,1 h and 1 d after termination of application. The results were assessed according to a school-mark-ing system where 0 is the top mark and 5 is the bottom mark.

Degree of gloss Determination of the degree of gloss was carried out according to DIN 67530 on double-layer coats of varnish on wood using a standard refractometer Laborsond 20 sold by Byk at an angle of 60 ~.

Film formation on metal sheeting The dispersion was applied to metal plates grade St 1405 by means of a film 25 spreader so as to produce a coating having a wet thickness of 1 50 to 200,um,which was then predried at room temperature for 1 0 minutes prior to baking.

Square-cut Adhesion Test 30 This test was carried out in accordance with DIN 53,151.

Surface Hardness The hardness (pendulum impact hardness) of the film was determined in 35 accordance with DIN 53,157 using a king tool. The table gives the time in seconds.

CA 0221983~ 1997-11-20 sELLscHA~ ozoo5~/47497 Acetone Test A swab of cotton wool impregnated with the solvent was stroked forwards and backwards over a selected area of the coated metal whilst exerting slight pressure. One stroke forwards followed by one stroke backwards equals one reciprocal stroke (rs) This test was carried out over a range up to 50-100 recipro-cal strokes. If no film is removed over this range, it is regarded as being cross-linked or cured.

28% Sulfuric Acid Test This test was carried out according to instructions provided by the company DKH (Dr. Kurt Herberts), Wuppertal, as follows:

A small swab of cotton-wool impregnated with 28% strength sulfuric acid was placed on the test piece. Following a period of 4 hours in a circulating drier at 60~C, the sample was assessed in accordance with DIN 53,230 Tab. 1.

38% Sulfuric Acid Test This test was carried out in a similar manner to the 28% sulfuric acid test except that the sample was left to stand for 24 hours at room temperature.

Claims (12)

1. Aqueous dispersions, containing a polyurethane (A), mit structural units derived from compounds of formula (I) in which the substituents have the following meanings:

R1,R2,R3 independently denote hydrogen, C1-C24 alkyl or C6-C24 alkenyl R4 denotes hydrogen R5,R6 a) together denote C4-C10 alkanediyl, b) each denotes C2-C10 alkyl, C5-C8 cycloalkyl or C7-C20 aralkyl, C) each denotes a hydroxyl- terminated poly(C2-C4 alkylene oxide), or d) one radical R5 or R6 has the meaning stated under (a) to (c) and the other is hydrogen or a radical of the formula II

in which X denotes C2-C6 alkanediyl and R7 has the same meaning as R5 or R6 except that R7 does not denote a radical of the formula II, where - the radicals R5 and R6 in each of the cases (a) and (d) carry a total of one (1) hydroxyl group attached to an aliphatic carbon atom, - optionally the radical R5 and/or R6 carries 1 or 2 hydroxyl groups bonded to an aromatic carbon atom or one nitrile, tertiary amino, carboxylic acid or sulfonic acid group which are optionally present in the form of their salts, and- the average functionality (F) of all structural components of the polyurethane(A) is from 1.5 to 2.2, based on the functionalities which interreact during thesynthesis of the polyurethane (A) in an addition reaction.

2. Polyurethane dispersions as defined in claim 1 wherein the average functionality (F) is from 1.7 to 2Ø

3. Polyurethane dispersions as defined in claim 1 or claim 2, wherein the concentration of the carbonyl groups of the structural elements derived from the compounds of formula (I) in the polyurethane is from 3 to 140 mmol per 100g of polyurethane (A).

4. A process for the preparation of polyurethane dispersions as defined in any of claims 1 to 3, comprising the process steps 1. Preparation of a polyurethane by causing the reaction of a) polyvalent isocyanates containing from 4 to 30 carbon atoms, b) polyols, of which b1) from 10 to 100 mol, based on the total weight of the polyols (b), have a molecular weight of from 500 to 5000 and b2) from 0 to 90 mol, based on the total amount of the polyols (b), are difunctional and have a molecular weight of from 62 to 500 g/mol, c) compounds of the formula I, d) optionally other polyvalent compounds containing reactive groups and differing from the monomers (b) and (c), said groups being alcoholic hydroxyl groups or primary or secondary amino groups and e) monomers differing from the monomers (a), (b), (c) and (d) and containing at least one isocyanate group or at least one isocyanate-reactive group and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, by which means the polyurethanes are rendered water-dispersible.

II. Dispersion of the polyurethane obtained in step I in water.

5. Aqueous dispersions as defined in any of claims 1 to 3, containing, in addition to polyurethane (A) a cross-linking agent (B) containing at least one aldehyde group or at least 2 functional substituents selected from thegroup consisting of primary amino group, secondary amino group, hydrazine group,hydrazide group, isocyanate group, blocked isocyanate group and aminooxy group.

6. Aqueous dispersions as defined in claim 5, wherein the amounts of component (A) and (B) are such that the molar ratio of the carbonyl groups of the structural elements derived from the compounds of formula (I) to the functional substituents of the cross-linking agent (B) is from 0.5:1 to 5:1.

7. Aqueous containing dispersions as defined in any of claims 1to 6, containing:

(I) from 15 to 30 wt% of a binding agent, essentially consisting of polyurethane (A) and the cross-linking agent (B) (II) from 7 to 15 wt% of a pigment (III) from 2 to 5 wt% of an alcohol that is suitable for use as solvent (IV) from 4.5 to 10 wt% of conventional additives (V) from 45 to 70 wt% of water.

8. Aqueous dispersions as defined in claim 7, containing polyhydrazides as across-linking agents (B).

9. A process for coating wood, glass, plastics material, leather, paper or metal, wherein an aqueous dispersion as defined in any of claims 5 to 8 is applied to any of said substrates and dried.

10. A process for printing paper or metal foils or plastics films, wherein said media are printed with a dispersion as defined in claim 7 or claim 8.

11. A process as defined in claim 10, wherein the medium printed is a plastics film having a surface tension of from 30 to 50 mN/m.

12. Objects whenever produced by the process defined in any of claims 9 to 11.