DE3903804A1 - Aqueous coating dispersions and their use - Google Patents

Abstract

Aqueous coating dispersions are disclosed which consist of a polyurethane resin, pigments and other conventional auxiliaries and additives; also disclosed is the use of these coating dispersions as a basecoat for the production of multicoat systems in the paint-processing industry, in particular for the coating of hard surfaces, and preferably for original finishes (OEM finishes). These coating dispersions are characterised by a specific polyester, which contains hydroxyl and carboxyl groups and which is used to prepare the polyurethane resin. Furthermore, this polyurethane resin is obtained as an aqueous dispersion by reacting said specific polyester with at least one diol and at least one diisocyanate, to give an intermediate product which contains terminal hydroxyl groups, then reacting this product with at least one polyisocyanate, and finally transferring the polyurethane resin to a predominantly aqueous phase.

Description

The present invention relates to aqueous paint dispersions Polyurethane base, especially as a basecoat for the manufacture development of multilayer coatings in the lacquer-processing Industry, in particular for painting hard surfaces, can be used.

Advantageously, the aqueous Lackdisper invention tions in the initial coating of automobile bodies ver be used.

In the paint processing industry Mehrschichtlackie ments preferred according to the so-called "Base Coat Clear Coat" - Method applied, d. h., it becomes a pigmented base varnish pre-varnished and after a short drying time without baking step (wet-on-wet process) overcoated with clear lacquer. to Finally basecoat and clearcoat are baked together.

Especially with the metallic effect paints leads the Zweischichtver drive both visually and technologically to very high paint finishes.  

However, the basecoat has to ge a number of se merge with different properties. Especially this is true to a large extent for aqueous basecoats, because of the particular physical properties of the solvent water Consideration must be taken.

In US-A-45 58 090 are coating compositions for the preparation of Base layer of multilayer coatings described that an aqueous dispersion of a polyurethane resin with the Acid number 5 to 70 exist. These aqueous polyurethane dispersants sion, in addition to the binder pigments and conventional additives substances and optionally further binder components may be produced by reaction

• A. a linear polyether and / or polyester diol with terminal hydroxyl groups and a molecular weight from 400 to 3000 with
• B. a diisocyanate and
• C. a compound containing two towards isocyanate groups reactive groups and at least one for anion formation having enabled group, wherein the anion formation qualified group before implementation with a tertiary Amine has been neutralized

to an intermediate with terminal isocyanate groups, Transfer of the obtained from A, B and C intermediate in a predominantly aqueous phase and

• D. Reaction of the remaining isocyanate groups with a Di- and / or polyamine with primary and / or secondary Amino groups.

DE-OS 35 45 618 describes base Beschichtungszusammenset tongues containing a polyurethane resin as film-forming material an acid number of 5 to 70, which produced has been out by

• A. linear polyether and / or polyester diols having a Molecular weight from 400 to 3000,  
• B. diisocyanates and
• C. Compounds which have two opposite isocyanate groups contain active groups, wherein at least part of the compounds used as component C at least a group capable of forming anions, which preferably before the reaction with a tertiary amine has been neutralized,

a terminal isocyanate group-containing intermediate has been prepared, whose free isocyanate groups subsequently with

• D. further, isocyanate-reactive groups, namely one containing at least three hydroxyl groups the polyol

have been implemented.

The polyurethane resin prepared as described above Dispersions are very good film formers. They are, however unable to stand up for the metal effect and state safety necessary to produce rheological properties, without those used in the examples of US-A-4,558,090 Thickener based on alkali metal phyllosilicates be set. However, these have the disadvantage that due their strong basic character, the aluminum particles in part be decomposed, which can lead to evolution of hydrogen.

In addition, the condensation resistance of repair Coatings strongly influenced at low stoving temperatures adversely.

Other disadvantages of these prior art polyurethane resins nik are to be seen in their manufacturing process.

First, the compounds C to be used are next to two isocyanate-reactive groups at least one  have the group capable of anion binding, for example Dihydroxyalkyl (di) carboxylic acids, because of their chemical structure very sparingly soluble in the organic solvents used. Consequently, one must deal with inhomogeneous reaction mixtures, which become homogeneous only as the reaction progresses. more towards the chain extension takes place with the at least three Hydroxyl-containing polyols, as in the above-mentioned DE-OS described, only very slowly and is therefore with associated with a great deal of time.

The present invention was therefore based on the object, a new aqueous coating dispersion with respect to the prior art to provide improved properties.

The present invention relates to aqueous paint dispersions, consisting of

• A. a polyurethane resin having an acid number of 5 to 40 as a film former obtained by reacting a poly esters, at least one diol and a diisocyanate,
• As pigments and
• C. other customary auxiliaries and additives,

which are characterized in that

• - The polyester used for polyurethane resin production a hydroxyl group and carboxyl group-containing Polyester is,
• - And this polyurethane resin is obtained as an aqueous dispersion th by
  reacting this polyester (a) together with at least one diol (b) and at least one diisocyanate (c), optionally dissolved in a solvent, to form a hydroxyl end-group-bearing intermediate,
  then this product with at least one polyisocyanate cyanate (d) is reacted
  and converting the polyurethane resin into the predominantly aqueous phase.

The component (a) in the film-forming poly according to the invention urethane resin A used Hydroxylgrupppen- and Carboxylgrup Pen-containing polyester are basically after the Expert made known rules of polyester production. In this context, Wagner, Sarx, Lackkunstharze, Karl Hanser-Verlag, 5th edition, pages 86-99 referenced.

However, it is necessary that partially trifunctional compo be used.

As trifunctional components, triols, tricarboxylic acids, Dihydroxycarboxylic acids, hydroxycarboxylic acids and dihydroxysulfone acids are used. Preference is given to tricarboxylic acids and Dihydroxymonocarboxylic.

In the production of polyester, care must be taken that a final acid number ( SC ) is achieved, which can be calculated by the following formula:

M _t = mol trifunctional component
E _COOH = Equivalent COOH
E = weight (g)

As trifunctional esterification components, for example trimethylolpropane, glycerin, trimellitic acid, malic acid, Aconitic acid, bishydroxyethyltaurine and dimethylolpropionic acid be used.

Otherwise, all customary for the production of polyester Raw materials are used, such as:  

Ethylene glycol, propylene glycol, butanediol, pentanediol, hexane diol, neopentyl glycol, dimethylol cyclohexane, hydroxypivaline acid monopentyl glycol ester, adipic acid, succinic acid, Glutaric acid, maleic acid, fumaric acid, itaconic acid, azelaine acid, sebacic acid, dimer fatty acid, phthalic acid, iso- and Terephthalic acid and tetra- and hexahydrophthalic acid. It The anhydrides can also be used as far as they are concerned exist.

These polyesters preferably have a molecular weight of 300 to 2000, a hydroxyl number of 56 to 374, and an acid number from 28 to 187.

As component b, for the preparation of the polyurethane resin used in the paint according to the invention, all diols come in Consider how well known from polyurethane chemistry are. An overview can be found in the book by K. Weigel, Poly urethane lacquers 1966, Holz-Verlag, pp. 91-129. Own this preferably a molecular weight of from 62 to 2000 Also include the polyethers such as polypropylene glycol and Polybutandiol-1,4 as well as the polyester, which by ring-opening Polymerization of lactones are accessible.

As component c, for the preparation of the polyurethane resin is used in the paint according to the invention, are in principle all diisocyanates usable. An overview of this is the above mentioned book by K. Weigel, pp. 12-49. Preferred are however, the aliphatic and cycloaliphatic:

Hexamethylene diisocyanate, cyclohexane diisocyanate, 1-isocyanato methyl-5-isocyanato-1,2,3-trimethylcyclohexane, bis (4-iso cyanatocyclohexyl) methane.

The preparation of the hydroxyl end-bearing Zwischenpro ucts by the use of the hydroxyl groups tra ing components in a stoichiometric excess.  

The reaction is preferably carried out in solvents which towards isocyanates are inert and at least partially with Water are miscible. It is advantageous to use such solvents which are also good solvents for polyurethanes and which can be easily removed from the aqueous dispersions. Particularly suitable solvents are methyl ethyl ketone, Acetone, methyl isopropyl ketone and methyl isobutyl ketone.

In this case, the components a and b are optionally presented with solvents medium and then the diisocyanate c is added with stirring. With the rate of addition, the exothermic reaction can be controlled very easily. Preferably, the temperature is maintained between 50 and 100 ° C, depending on the boiling point of the solvent used.

Of course, also in polyurethane chemistry be used with known catalysts. An overview this is the overview of K. Weigel, ibid. Pp. 130-136. Particularly preferred is dibutyltin dilaurate.

The amounts of components a and b are preferably selected the equivalents of the hydroxyl groups of a and b are 1: 10 to 1: 1, preferably 1: 5 to 1: 2, amount.

Preferably, the ratio of components (a + b) to c 1.03 to 2.5, especially 1.05 to 1.5.

The chain extending reaction of the hydroxyl groups included the intermediate is preferably treated with a functionali greater than 2 performed. The stoichiometric ratios are chosen so that in the chain extension branches arise, but networks are avoided. As a polyiso cyanates are preferably used triisocyanates, but it is also possible to use mixtures of tri- and diisocyanates the. Triisocyanates which are commercially available Trimerization products, either via biuret formation  or are built up by an isocyanurate ring structure, be used. However, it is also possible to use mixtures To produce triisocyanates and diisocyanates by in in laid diisocyanate a deficit of anhydrous triol is registered.

The chain-extended precursor is in the aqueous phase converted by first by neutralization with a water-soluble base, the acid groups are converted into anions become. As water-soluble bases are preferred volatile Amines used. An overview of this is given by the Austrian Patent No. 1 80 407. Particularly preferred are tertiary, Hydroxyl-containing, volatile amines. It is advantageous Add the neutralizing agent as an aqueous solution. After that Water is added with good stirring. After setting the pH to 6.5 to 8.5, the organic solvent is through Distillation removed in vacuo.

The resulting aqueous dispersions provide the filmbil dende material of the paint dispersions of the invention however, it may be advantageous to use other film-forming materials to share proportionally in order to specifically target certain characteristics to reach. These are melamine resins, polyester resins and Acrylate resins.

As crosslinkers, in addition to melamine resins, blocked poly isocyanates are used.

The paint dispersions of the invention are very well suited for incorporation of effect pigments, such as. As metal powders, in particular of aluminum, and / or pearlescent pigments. except the paint dispersions of the invention can color pigments and / or dyes.

The paint dispersions of the invention may optionally also contain organic solvents in amounts of 0 to 20%.  

In addition, they can conventional additives such as wetting agents, Stabilisa doors, defoamers, catalysts, leveling and thickening medium and dispersing aids.

The curing of the coating dispersions according to the invention, in particular but the basecoats, as usual together with the subsequently applied clearcoat. When using 2-Kom component clearcoat (hydroxyacrylate / polyisocyanate) are added low temperatures achieved good properties such as adhesion, Rockfall and water resistance. In particular, the show thus obtained basecoat paint films less swelling as basecoat paints according to DE-OS 35 45 618 and the US-A-45 58 090. The layer thicknesses are preferably from 10 to 25 μm dry film thickness for the basecoat of 30 to 60 μm for the clearcoat film. As clearcoats are basically all known transparent drying coating ge suitable.

In the following examples, the invention will be closer purifies. All quantities are by weight, if not expressly stated otherwise. The viscosity was according to DIN 53 211 with a 4 mm nozzle at 20 ° C determined.

Reference Example 1 (Polyester A)

In a four-necked flask equipped with a stirrer, a thermometer ter and a packed column are 416 Parts of neopentyl glycol, 268 parts of dimethylolpropionic acid and 584 Parts adipic acid melted and then under Stir heated so that the column top temperature does not reach 100 ° C exceeds.

The temperature of the reaction mixture should not be more reach as high as 220 ° C. It is esterified until one Acid number of 100 is reached.

The viscosity is 75% in methyl ethyl ketone, 40 sec, measured in 4 mm cup.  

Reference Example 2 (Polyester B)

In a four-necked flask according to Reference Example 1 1416 parts of 1,6-hexanediol are melted together with 1680 parts of a dimeric technical C ₁₈ fatty acid (Pripol 1009, Unichema, (99% dimer, 1% trimer, traces of monomer)). Then 498 parts of isophthalic acid are added with stirring and the temperature is increased so that the top temperature of the columns does not exceed 100 ° C.

At a maximum temperature of the reaction mixture of 220 ° C is esterified until an acid number of 3 is reached. After cooling to 170 ° C, 576 parts Trimellitic anhydride added and at 170 ° C on esterified until an acid number of 44 is reached.

After cooling to 80 ° C with methyl ethyl ketone to a Solid content of 85% diluted. The viscosity is 78 sec, diluted to a solids content of 60% with Butyl glycol, measured in 4 mm cup.

Reference Example 3 (Polyester C)

In a four-necked flask according to Reference Example 1, 208 parts of neopentyl glycol, 236 parts of 1,6-hexanediol together with 292 parts of adipic acid and 280 parts of dimeric C ₁₈ technical fatty acid (Pripol 1009, Unichema, (99% dimer, 1% trimer, trace Monomer) is melted and then with stirring, the temperature is increased so that the top temperature of the column does not exceed 100 ° C.

At a maximum temperature of the reaction mixture of 220 ° C is esterified until an acid number of 3 is reached. After cooling to 170 ° C, 96 parts Trimellitic anhydride added and at 170 ° C on esterified until an acid number of 29 is reached.  

The viscosity is 75% in methyl ethyl ketone 41 sec, measured in 4 mm cup.

Reference Example 4 (Polyester D)

In a four-necked flask according to Reference Example 1, 832 parts of neopentyl glycol are melted together with 2240 parts of a C ₁₈ dimeric fatty acid (Pripol 1009, Unichema (99% dimer, 1% trimer, trace monomer)). Subsequently, the temperature is increased so that the Ko lonnenkopftemperatur does not exceed 100 ° C. At a maximum temperature of the reaction mixture of 220 ° C is esterified until an acid number of 3 is reached. After cooling to 170 ° C, 384 parts of trimellitic anhydride are added and further esterified until an acid number of 36 is reached. After cooling to 80 ° C is diluted with methyl ethyl ketone to a solids content of 80%. The viscosity is, in the ratio 1: 1 mixed with butyl glycol, 22 sec, measured in a 4-mm cup.

Production of a chain extender

In a four-necked flask with attached stirrer, thermometer and reflux condenser are 917 parts of 4,4'-diisocyanatodicyclo hexylmethane together with 0.2 parts of dibutyltin dilaurate placed. 10 portions are added to this mixture at 40 ° C Add 9.38 parts of trimethylolpropane, taking care is that the temperature of the reaction mixture is not 65 ° C. exceeds.

From the 5th portion is started, with anhydrous methylethyl to dilute ketone, so that in the end a solids content of 50% is achieved. The NCO content is 9.98%. You get a room temperature gelatinous mass at about 50 ° C becomes fluid.  

example 1

In a four-necked flask with attached stirrer, thermometer and reflux condenser are 169 parts of polyester A together with 177 parts of 1,6-hexanediol and 453 parts of anhydrous methyl ethyl ketone and 0.2 parts of dibutyltin dilaurate at 40 ° C he warms. Then, within half an hour, 333 Parts of isophorone diisocyanate added. The Tempe rises temperature to 62 ° C. After completion of the addition is maintained at 79 ° C. until all the isocyanate has reacted.

The viscosity is 19 sec.

Now 564 parts of methyl ethyl ketone, 0.3 parts Dibutyltin dilaurate and 40 parts of Desmodur N 3390 (Bayer AG; Trimerized hexamethylene diisocyanate, 90%, NCO content 19.23%) added.

It is stirred at 79 ° C until the viscosity is 1: 2, with butyl diluted glycol, 26 sec.

Then a mixture of 11 parts of N, N-dimethylamino is allowed ethanol and 830 parts of deionized water. to closing is in vacuo at 50 to 60 ° C, the methyl ethyl ketone distilled off. This gives a finely divided dispersion with a Solids content of 32% and a pH of 8.0. The vis The viscosity is 17 sec.

Example 2

In a four-necked flask according to Example 1, the output However, instead of the 40th Parts Desmodur N 3390 77 parts of the chains described above used extensor.

It is then stirred at 79 ° C until the viscosity, 1: 2 with Butyl glycol diluted, 39 sec.  

The procedure is as described in Example 1.

The dispersion has a solids content of 25% and a Viscosity of 19 sec, measured in a 4 mm cup.

Example 3

In a four-necked flask according to Example 1 1824 parts Polyester B together with 600 parts of hexanediol 1.6 915 parts anhydrous methyl ethyl ketone and 2.7 parts dibutyltin dilaurate heated to 40 ° C with stirring. Then be with stirring, 1356 parts of isophorone diisocyanate within 2 h added, the temperature rises to 79 ° C. The Tem temperature of the reaction mixture is kept at 79 ° C until all the isocyanate has reacted (about 4 h).

Subsequently, 4073 parts of anhydrous methyl ethyl ketone added and then along with 453 parts of the chain extender described above at 79 ° C stirred until the viscosity 1: 2 in butyl glycol 36 sec is, measured in the 4-mm cup.

Now allowed a mixture of 108 parts of N, N-dimethylamino ethanol and 8580 parts of deionized water. to closing is in the vacuum at 50-60 ° C, the methyl ethyl ketone distilled off. This gives a finely divided dispersion with a Solids content of 30%, a pH of 8.0 and a Viscosity of 36 sec.

Example 4

In a four-necked flask according to Example 1, the output However, in place of the Chain extender 133 parts Desmodur N 3390 (Bayer AG, Tri polymerized hexamethylene diisocyanate, 90%, NCO content 19.23%).  

This gives a finely divided dispersion with a solid content of 30%, a pH of 7.95 and a viscosity from 33 sec.

Example 5

In a four-necked flask according to Example 1, 608 parts Polyester C together with 35 parts of 1,6-hexanediol, 518 parts anhydrous methyl ethyl ketone and 0.2 part dibutyltin di laurate with stirring to 40 ° C heated. Then 133 parts Isophorone diisocyanate added. The temperature rises afterwards within 20 min at 63 ° C. The reaction mixture is on Heated to 79 ° C and stirred at this temperature until everything Has reacted isocyanate.

After adding 711 parts of anhydrous methyl ethyl ketone 317 parts of the chain extender added and at 79 ° C. stirred until a viscosity of 1: 2 in butyl glycol, of 44 sec reached, measured in 4 mm cup.

Now a mixture of 22 parts of N, N-dimethylaminoethanol and 1967 parts of water were added and then the methyl Ethyl ketone distilled off at 50-60 ° C in vacuo. You get a finely divided dispersion having a solids content of 31%, a pH of 8.25 and a viscosity of 34 sec.

Example 6

In a four-necked flask as in Example 1, 462 parts Polyester D together with 122 parts 1,6-hexanediol, 0.2 parts Dibutyltin dilaurate and 200 parts of anhydrous methylethyl Ket with stirring to 40 ° C heated. Then 283 parts Isophorone diisocyanate added within half an hour. The temperature rises to 75 ° C. The reaction mixture is heated to 79 ° C and continue at this temperature stirred until all the isocyanate has reacted.  

Thereafter, 732 parts of anhydrous methyl ethyl ketone, 0.5 Parts of Desmodur N 3390 (Bayer AG; Trimerized Hexamethylene diisocyanate, 90%, NCO content 19.23%) is added and it is while stirring at 79 ° C until the viscosity of 1: 2 in butyl Glykol 45 sec, measured in 4-mm cup. Now one is Mixture of 23 parts N, N-dimethylaminoethanol and 1982 parts run in deionized water.

Subsequently, the methyl ethyl ketone at 50-60 ° C in a vacuum distilled off. This gives a finely divided dispersion with a Solids content of 30%, a pH of 8.35 and a Viscosity of 47 sec, measured in a 4 mm cup.

Comparative Example I according to DE 35 45 618, Preparation of polyurethane dispersion

In an apparatus as in Example 1, 102 parts of a Polyesters of 1,6-hexanediol and isophthalic acid with a average molecular weight of 614, along with 99 parts a polypropylene glycol having an average molecular weight of 600 and 40 parts of dimethylolpropionic acid at 100 ° C heated and dehydrated in vacuo for 1 h.

At 80 ° C, 210 parts of 4,4'-dicyclohexylmethane diisocyanate added. After 16 h at 80 ° C, the isocyanate content 1.45%.

Now 10 parts of trimethylolpropane and then 0.2 Parts of dibutyltin dilaurate added. After two hours of stirring at 80 ° C 630 parts of methyl ethyl ketone are added and at 80 ° C further stirred. After 17 h, the viscosity is measured in a 4 mm beaker (sample 2: 3 diluted in N-methylpyrrolidone) 61 sec.

After adding a mixture of 9 parts of N, N-dimethylamino ethanol and 1060 parts of deionized water becomes the methyl Ethylketone distilled off in vacuo. You get a milky Dispersion with a solids content of 32%, a pH  of 7.3 and a viscosity of 26 sec, measured in 4-mm Cup.

= Application example (preparation of basecoats) 1. aluminum pigments

A commercial paste is used with an aluminum miniumgehalt of 65% and an average particle size of 15 μm.

2. Preparation of a water-soluble polyester (non-inventive general component of Basecoats)

In a four-necked flask as described in Reference Example 1, 472 parts of 1,6-hexanediol, 624 parts of neopentyl glycol and 1,224 parts of hydroxypivalic acid neopentyl glycol ester for Melting brought. Then, with stirring, 1328 parts Added isophthalic acid. Subsequently, the temperature increased so that the column head temperature is not 100 ° C exceeds. The temperature of the reaction mixture should be Do not exceed 220 ° C. It is esterified until the Acid number is less than 5. After cooling to 170 ° C 768 parts of trimellitic anhydride are added and further esterified until an acid number of 31 is reached.

After cooling to 130 ° C with butyl glycol on a Solids content of 70% diluted. The viscosity is 40% in butylglycol 52 sec, measured in a 4 mm cup.

3. melamine resin

It is a commercial melamine resin with high Ver ether degree used, 80% in isobutanol.  

4. thickener

The thickener is an emul based on methacrylic acid anionic polymer used by BASF AG under the Name Latekoll D is sold, and which with deionized water and N, N-dimethylaminoethanol to one pH of 7.00 and a solids content of 8% becomes.

The basecoats are produced according to the following basic recipe:

Aluminum paste 65% 2.9 butylglycol 2.9 Water soluble polyester 70% 3.9 80% melamine resin 3.4 N, N-dimethylaminoethanol 10% 0.9 deionized water 4.6 Polyurethane dispersion 25% @ according to Example 1 to 6 35.7 deionized water 18.3 Thickener 8% 9.1 deionized water  18.3 100.0

Comparative Example II

With the polyurethane dispersion of Comparative Example I is prepared according to the teaching of US-A-45 58 090 a basecoat.  

Thickener (Thickener 2 of US Patent):

A paste of sodium magnesium fluorine lithium silicate with a solids content of 3% is produced by the Silicate is stirred with the aid of a dissolver in water. After standing overnight, the paste is repeated for 10- Stirred for 15 min.

Preparation of the basecoat (according to US-A-45 58 090):

25 parts of the thickening agent are added with stirring Added parts of the polyurethane dispersion.

For this purpose, successively with stirring 2 parts of melamine resin, 5 Parts of the polyester (70% in butylglycol), 0.5 parts of a 10% aqueous solution of N, N-dimethylaminoethanol and 10 Parts of the 1: 1 in butylglykol angeteigten aluminum pigment paste. After stirring for 30 minutes, 32.5 parts are deionized Water added.

All basecoats are made in the usual way with Zinkphos phatierung, electrocoat and spray pretreated Sheet metal with a pneumatically atomizing spray gun so on worn, that in 2 application layers a layer thickness of 15 microns is achieved. After application the beschich Teten sheets dried for 5 min at 80 ° C and in the usual way with a commercially available acrylate / melamine resin clearcoat over stratified and baked at 130 ° C for 30 min. On the so forth Plates are applied with a refinish, the same basecoats are used, but as clear paint a commercial 2-component clearcoat based Polyhydroxyacrylate / polyisocyanate is used. einbrenn conditions for 45 min at 80 ° C.  

The plates thus produced become after three days of storage at room temperature for 10 days in 32 ° C warm water. Subsequently, the paints are assessed visually.

After four weeks storage of the basecoats at room temperature are once again produced first coats and Ver assessed visually to the fresh paint.

The results are summarized in the following table.

Claims (13)

1. Aqueous paint dispersions consisting of

• A) a polyurethane resin having an acid number of 5 to 40 as a film former, obtained by reacting a poly ester, at least one diol and a diisocyanate,
• B) pigments and
• C) other customary auxiliaries and additives,

characterized in that

• the polyester used for the production of polyurethane resin is a polyester containing hydroxyl groups and carboxyl groups,
• - And this polyurethane resin is obtained as an aqueous dispersion th by
  reacting this polyester (a) together with at least one diol (b) and at least one diisocyanate (c), optionally dissolved in a solvent, to form a hydroxyl end-group-bearing intermediate,
  then this product with at least one polyisocyanate cyanate (d) is reacted
  and converting the polyurethane resin into the predominantly aqueous phase.

2. paint dispersions according to claim 1, characterized that the poly used for the preparation of the polyurethane resin ester has a molecular weight of 300 to 2000, a hydroxyl number from 56 to 374 and an acid number of 28 to 187. 3. paint dispersions according to claim 1 or 2, characterized marked characterized in that the polyester is obtained by reacting min at least one mono-, di- or polycarboxylic acid or reactive  Derivatives of these acids, with one or more diols or Triols, in conjunction with a trifunctional component, selected from among triols, tricarboxylic acids, dihydroxy carboxylic acids, hydroxydicarboxylic acids and hydroxysulfonic acids existing group. 4. paint dispersions according to claim 1, characterized that the diol used for polyurethane resin preparation a Molecular weight of 62 to 2000 has. 5. paint dispersions according to claim 1, characterized that the polyisocyanate used is a triiso cyanate or a diisocyanate (s) containing triisocyanate han delt. 6. paint dispersions according to claims 1 to 5, characterized marked characterized in that one chooses the amount of components a) and b), the equivalents of the hydroxyl groups of a) and b) are 1:10 to 1: 1, preferably 1: 5 to 1: 2. 7. paint dispersions according to claims 1 to 5, characterized marked characterized in that the ratio of the components (a + b) to c so chooses that it is 1.03 to 2.05, preferably 1.05 to 1.5 is. 8. paint dispersions according to claims 1 to 7, characterized marked characterized in that the intermediate hydroxyl-containing product is given by adding component c) to one if necessary diluted in a solvent, mixture of the compo dosed a) and b). 9. paint dispersions according to claims 1 to 8, characterized ge indicates that this additional additional film-forming Ma materials, such as melamine resins, polyester resins and / or acrylate contains resins.   10. paint dispersions according to claims 1 to 9, characterized ge indicates that these as pigments metal powder, preferably Aluminum powder, pearlescent pigments, color pigments or color contain substances. 11. Use of the lacquer dispersions according to claims 1 to 10 as basecoat for the production of multilayer coatings in the paint industry, especially for painting hard surfaces. 12. Use of paint dispersions according to claim 11, in particular especially for automotive coatings, as a first coat.