DE3903804C2 - Aqueous paint dispersions and their use - Google Patents

Description

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

The aqueous lacquer dispersers according to the invention can be used with advantage sions in the initial painting of automobile bodies be applied.

In the paint processing industry, multi-layer paint is used preferred according to the so-called "Base Coat Clear Coat" - Process applied, d. that is, it becomes a pigmented base lacquer pre-coated and after a short flash-off time without baking step (wet-on-wet process) overcoated with clear lacquer. On finally the basecoat and clearcoat are baked together.

The two-layer coating is especially useful for metallic effect paints drive both optically and technologically very high paintwork.  

However, the basecoat must have a number of ge unite opposing properties. Especially this applies to a large extent to aqueous basecoats because of the special physical properties of the solvent water Must be taken into account.

US Pat. No. 4,558,090 describes coating compositions for the production of the base layer of multilayer coatings which consist of an aqueous dispersion of a polyurethane resin with an acid number of 5 to 70. This aqueous polyurethane dispersion, which in addition to the binder can contain pigments and conventional additives and, if appropriate, further binder components, is prepared by reaction

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

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

• A) implementation of the isocyanate groups still present with a Di- and / or polyamine with primary and / or secondary Amino groups.

DE-OS 35 45 618 describes basic coating compositions which contain as the film-forming material a polyurethane resin with an acid number of 5 to 70, which has been prepared by

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

an intermediate product having terminal isocyanate groups has been produced, the free isocyanate groups then eating with

• A) further groups reactive towards isocyanate groups, namely contain at least three hydroxyl groups the polyol

have been implemented.

The polyurethane resin Dispersions are very good film formers. However, they are unable to stand for metal effect formation and to generate safety necessary rheological properties, without using those in the examples of US-A-4,558,090 Thickener based on alkali layer silicates be set. However, these have the disadvantage that due to The aluminum particles are partly due to their strongly basic character decompose, which can lead to hydrogen evolution.

In addition, the condensation resistance of repair painting at low baking temperatures strongly affected is pregnant.

Further disadvantages of these polyurethane resins of the prior art nik can be seen in their manufacturing process. First of all, the compounds to be used are C, in addition to two groups reactive toward isocyanates at least one  have a group capable of binding anions, for example Dihydroxyalkyl (di) carboxylic acids, because of their chemical structure very poorly soluble in the organic solvents used. You have to deal with inhomogeneous reaction mixtures which only become homogeneous as the reaction progresses. Next the chain is extended with the at least three Polyols containing hydroxyl groups, as mentioned in the above ten DE-OS described, only very slowly and is therefore with a lot of time involved.

The present invention was therefore based on the object new aqueous paint dispersion with compared to the prior art to provide improved properties.

The present invention relates to aqueous paint dispersions consisting of

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

which are characterized in that

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

The component (a) in the film-forming poly according to the invention Urethane resin A used hydroxyl groups and carboxyl groups Pen-containing polyesters are generally made according to the Rules of polyester production known to those skilled in the art are produced. In this context, Wagner, Sarx, lacquer synthetic resins, Karl Hanser-Verlag, 5th edition, pages 86-99.

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

Triols, tricarboxylic acids, Dihydroxycarboxylic acids, hydroxycarboxylic acids and dihydroxysulfone acids are used. Tricarboxylic acids and are preferred Dihydroxy monocarboxylic acids.

When manufacturing polyester, it is important to ensure that a final acid number (SZ) is reached, which can be calculated using the following formula:

M _t = mole of trifunctional component
E _COOH = equivalents of COOH
E = weight (g)

As trifunctional esterification components, for example wise trimethylolpropane, glycerin, trimellitic acid, malic acid, Aconitic acid, bishydroxyethyl taurine and dimethylol propionic acid be used.

Otherwise, all raw materials common for polyester production can be used, such as:
Ethylene glycol, propylene glycol, butanediol, pentanediol, hexane diol, neopentyl glycol, dimethylolcyclohexane, Hydroxypivalin säuremononeopentylglykolester, adipic acid, succinic acid, glutaric acid, maleic acid, fumaric acid, azelaic acid, sebacic acid, dimer fatty acid, phthalic acid, isophthalic and terephthalic acid, and tetra- and Hexahydrophthalic acid. The anhydrides can also be used if they exist.

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

As component b, which is used for the production of the polyurethane resin is used in the lacquer according to the invention, all diols come in Consider how they are well known from polyurethane chemistry are. The book by K. Weigel, Poly provides an overview of this urethane paints 1966, Holz-Verlag, pp. 91-129. Own them preferably a molecular weight of 62 to 2000. To do this also include the polyethers such as polypropylene glycol and Polybutanediol-1,4 as well as the polyesters by ring-opening Polymerization of lactones are accessible.

In principle, all diisocyanates can be used as component c, which is used for the production of the polyurethane resin in the lacquer according to the invention. The above-mentioned book by K. Weigel, pp. 12-49, provides an overview of this. However, the aliphatic and cycloaliphatic are preferred:
Hexamethylene diisocyanate, cyclohexane diisocyanate, 1-isocyanato methyl-5-isocyanato-1,2,3-trimethylcyclohexane, bis (4-iso cyanatocyclohexyl) methane.

The production of the intermediate pro-hydroxyl end groups duktes takes place through the use of the hydroxyl groups tra components in a stoichiometric excess.  

The reaction is preferably carried out in solvents which are inert to isocyanates and at least partially with Water are miscible. It is advantageous to add such solvents use, 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.

Components a and b are optionally dissolved submitted medium and then the diisocyanate c under Stirring added. With the rate of addition, the exothermic reaction can be easily controlled. Prefers the temperature is kept between 50 and 100 ° C, depending on Boiling point of the solvent used.

Of course, those in polyurethane chemistry can also known catalysts can also be used. An overview the above-mentioned overview by K. Weigel, ibid. Pp. 130-136. Dibutyltin dilaurate is particularly preferred.

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

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

The chain-extending reaction of the hydroxyl groups included the intermediate is preferably with a functional act greater than 2 carried out. The stoichiometric ratios are chosen so that branches extend when the chain is extended arise, but networking is avoided. As a polyiso Triisocyanates are preferred, but it is also possible to use mixtures of tri and diisocyanates the. The commercially available triisocyanates Trimerization products, either via biuret formation  or be built up by an isocyanurate ring structure, be used. However, it is also possible to mix mixtures Triisocyanates and diisocyanates to be prepared by in front placed diisocyanate a deficit of anhydrous triol is entered.

The chain-extended preliminary product is in the aqueous phase transferred by first by neutralization with a water-soluble base converted the acid groups into anions will. Volatile are preferred as water-soluble bases Amines used. The Austrian gives an overview Patent No. 180 407. Particularly preferred are tertiary, Volatile amines containing hydroxyl groups. It is beneficial 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 Distillation removed in vacuo.

The aqueous dispersions thus obtained represent the film Ending material of the paint dispersions according to the invention. It however, other film-forming materials may be beneficial to be used proportionately to target specific properties to reach. Melamine resins, polyester resins and Acrylic resins.

In addition to melamine resins, blocked poly Isocyanates are used.

The paint dispersions according to the invention are very suitable for incorporating effect pigments, such as. B. metal powders, in particular from aluminum, and / or pearlescent pigments. Except the paint dispersions according to the invention can do color pigments and / or dyes.

The coating dispersions according to the invention can, if appropriate also contain organic solvents in amounts of 0 to 20%.  

In addition, you can use common additives such as wetting agents, Stabilisa gates, defoamers, catalysts, flow and thickening contain medium and dispersing aids.

The hardening of the paint dispersions according to the invention, in particular but the basecoats, as usual, takes place together with the subsequently applied clear coat. When using 2-com component clear varnish (hydroxyacrylate / polyisocyanate) are used achieves good properties at low temperatures such as adhesion, Stone chip and water resistance. In particular, the Basecoat films thus obtained have less swelling as basecoat films according to DE-OS 35 45 618 and US-A-4 558 090. The layer thicknesses are preferably 10 to 25 µm dry film thickness for the basecoat layer from 30 to 60 µm for the clear coat. As clear coats are basically all known transparent drying coating agents is suitable.

The invention is explained in more detail in the following examples purifies. All quantities are weights, if not expressly stated otherwise. The viscosity was determined according to DIN 53211 with a 4 mm nozzle at 20 ° C.

Reference Example 1 (Polyester A)

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

The temperature of the reaction mixture should no longer be reach than 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 a 4 mm cup.  

Reference Example 2 (Polyester B)

In a four-necked flask according to Reference Example 1, 1,416 parts of 1,6-hexanediol are melted together with 1,680 parts of a dimeric technical C ₁₈ fatty acid (Pripol 1009, Unichema; (99% dimer, 1% trimer, trace monomer)). Then 498 parts of isophthalic acid are added with stirring and the temperature is increased so that the column top temperature does not exceed 100.degree.

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 continued at 170 ° C esterified until an acid number of 44 is reached.

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

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 a dimeric technical C ₁₈ fatty acid (Pripol 1009, Unichema; (99% dimer, 1% trimer, traces Monomer) melted and then the temperature increased with stirring so that the column top temperature 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 continued at 170 ° C esterified until an acid number of 29 is reached.  

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

Reference Example 4 (Polyester D)

832 parts of neopentyl glycol together with 2240 parts of a dimeric technical C ₁₈ fatty acid (Pripol 1009, company Unichema; (99% dimer, 1% trimer, trace monomer)) are melted in a four-necked flask according to Reference Example 1. Subsequently, the temperature is increased so that the Ko lonnenkopfschopf temperature does not exceed 100 ° C. At a maximum temperature of the reaction mixture of 220 ° C., esterification is carried out until an acid number of 3 is reached. After cooling to 170 ° C., 384 parts of trimellitic anhydride are added and further esterification is carried out 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, mixed in a ratio of 1: 1 with butyl glycol, is 22 seconds, measured in a 4 mm beaker.

Manufacture of a chain extender

In a four-necked flask with an 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 9.38 parts of trimethylolpropane added, being careful is that the temperature of the reaction mixture is not 65 ° C exceeds.

Beginning with the 5th serving, begin with anhydrous methylethyl Dilute ketone so that in the end a solids content of 50% is reached. The NCO content is 9.98%. You get a gelatinous mass at room temperature, which at about 50 ° C. becomes flowable.  

example 1

In a four-necked flask with an 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 to 40 ° C warms. Then 333 within half an hour Parts of isophorone diisocyanate added. The tempe rises temperature to 62 ° C. When the addition is complete, the temperature is kept at 79 ° C until everything isocyanate has reacted.

The viscosity is 19 sec.

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

The mixture is stirred at 79 ° C. until the viscosity is 1: 2 with butyl Glycol diluted, is 26 sec.

Then a mixture of 11 parts of N, N-dimethylamino is left Add ethanol and 830 parts of deionized water. On the methyl ethyl ketone is then closed in vacuo at 50 to 60 ° C distilled off. A finely divided dispersion with a Solids content of 32% and a pH of 8.0. The Vis cosiness is 17 sec.

Example 2

In a four-necked flask according to Example 1, the starting substances from Example 1 are implemented, but instead of the 40th Parts Desmodur N 3390 77 parts of the chain described above used for an extended period.

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

The procedure is as described in Example 1. The dispersion has a solids content of 25% and Viscosity of 19 seconds, 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 dibutyl tin dilaurate heated to 40 ° C with stirring. Then be with stirring, 1356 parts of isophorone diisocyanate within 2 hours added, the temperature rising to 79 ° C. The tem temperature of the reaction mixture is kept at 79 ° C until all isocyanate has reacted (approx. 4 h).

Thereupon 4073 parts of anhydrous methyl ethyl ketone added and then together with 453 parts of the Chain extender described above as long as at 79 ° C. stirred until the viscosity 1: 2 in butyl glycol 36 sec is measured in a 4 mm cup.

Now a mixture of 108 parts of N, N-dimethylamino is left Add ethanol and 8580 parts of deionized water. On the methyl ethyl ketone is then closed in vacuo at 50-60 ° C distilled off. A finely divided dispersion with a Solids content of 30%, a pH of 8.0 and one Viscosity of 36 sec.

Example 4

In a four-necked flask according to Example 1, the starting substances from Example 3 implemented, but instead of Chain extender 133 parts Desmodur N 3390 (Bayer AG; Tri Merized hexamethylene diisocyanate, 90%, NCO content 19.23%) used.  

A finely divided dispersion with a solid is obtained content of 30%, a pH of 7.95 and a viscosity from 33 sec.

Example 5

608 parts are placed in a four-necked flask according to Example 1 Polyester C together with 35 parts 1,6-hexanediol, 518 parts anhydrous methyl ethyl ketone and 0.2 parts dibutyltin di laurat heated to 40 ° C with stirring. Then 133 parts Isophorone diisocyanate added. The temperature then rises to 63 ° C within 20 min. The reaction mixture is on Heated 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 is reached, measured in a 4 mm cup.

Now a mixture of 22 parts of N, N-dimethylaminoethanol and 1967 parts of water were added and then the methyl distilled ethyl ketone at 50-60 ° C in a vacuum. You get a fine dispersion with 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 of 1,6-hexanediol, 0.2 parts Dibutyltin dilaurate and 200 parts of anhydrous methylethyl heated ketone to 40 ° C with stirring. 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 continues at this temperature stirred until all isocyanate has reacted.  

Then 732 parts of anhydrous methyl ethyl ketone, 0.5 Parts of Desmodur N 3390 (Bayer AG; trimerized hexamethylene diisocyanate, 90%, NCO content 19.23%) added and it is stirred at 79 ° C until the viscosity 1: 2 in butyl Glycol is 45 seconds, measured in a 4 mm beaker. Now one Mixture of 23 parts of N, N-dimethylaminoethanol and 1982 parts deionized water.

Then the methyl ethyl ketone at 50-60 ° C in a vacuum distilled off. A finely divided dispersion with a Solids content of 30%, a pH of 8.35 and one Viscosity of 47 seconds, measured in a 4 mm beaker.

Comparative Example I according to DE 35 45 618, preparation of the Polyurethane dispersion

In an apparatus as in Example 1, 102 parts of a Polyester from 1,6-hexanediol and isophthalic acid with a average molecular weight of 614, along with 99 parts a polypropylene glycol with an average molecular weight heated from 600 and 40 parts of dimethylolpropionic acid to 100 ° C. and dewatered in a vacuum for 1 h.

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

Now 10 parts of trimethylolpropane and then 0.2 Parts of dibutyltin dilaurate added. After stirring for two hours 630 parts of methyl ethyl ketone are added at 80 ° C. and at Stirred at 80 ° C. 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 The ethanol becomes ethanol and 1060 parts of deionized water distilled ethyl ketone 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 Cups.

Application example Production of the basecoats 1. Aluminum pigments

A commercially available paste with an aluminum is used minimum content of 65% and an average particle size of 15 µm.

2. Preparation of a water-soluble polyester (General component of. not according to the invention Basecoats)

In a four-necked flask, as described in reference example 1, 472 parts of 1,6-hexanediol, 624 parts of neopentyl glycol and 1224 parts of hydroxypivalic acid neopentyl glycol ester Brought melt. Then, with stirring, 1328 parts Isophthalic acid added. Then the temperature so increased that the column top temperature is not 100 ° C exceeds. The temperature of the reaction mixture should 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 diluted by 70%. The viscosity is 40% in butyl glycol 52 sec, measured in a 4 mm beaker.

3. Melamine resin

It is a commercial melamine resin with high Ver Degree of etherification used, 80% in isobutanol.  

4. Thickener

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

The basecoats are produced according to the following basic recipe.

65% aluminum paste 2.9 Butyl glycol 2.9 Water soluble polyester 70% 3.9 Melamine resin 80% 3.4 N, N-dimethylaminoethanol 10% 0.9 deionized water 4.6 25% polyurethane dispersion according to Examples 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 from comparative example I. a basecoat is produced according to the teaching of US-A-4,558,090.  

Thickener (Thickener 2 of the U.S. patent)

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

Production of the basecoat (according to US-A-4,558,090)

25 parts of the thickener are 25th with stirring Parts of the polyurethane dispersion were added.

For this purpose, 2 parts of melamine resin, 5 Parts of the polyester (70% in butyl glycol), 0.5 parts of one 10% aqueous solution of N, N-dimethylaminoethanol and 10 Portions of the 1: 1 pasted aluminum pigment in butyl glycol paste. After stirring for 30 minutes, 32.5 parts are deionized Water added.

All basecoats are applied in the usual way with Zinkphos Phating, electrocoat and spray primer Sheet metal with a compressed air atomizing spray gun worn that in 2 application layers a layer thickness of 15 µm is reached. After application, they are coated Teten sheets dried at 80 ° C for 5 min and in the usual way with a standard acrylic / melamine resin clear coat layers and baked at 130 ° C for 30 min. On that way repair plates are applied, using the same basecoats, but as clear lacquer is a commercially available 2-component clear lacquer based Polyhydroxyacrylate / polyisocyanate is used. Branding conditions 45 min at 80 ° C.  

The plates produced in this way are stored for three days placed in 32 ° C warm water at room temperature for 10 days. The paints are then assessed visually. After four weeks of storage of the basecoats at room temperature first paint jobs are made again and in Ver visually assessed for the fresh paintwork.

The results are summarized in the following table.  

Claims (11)

1. Aqueous paint dispersions consisting of

• A) a polyurethane resin with an acid number of 5 to 40 as film former, obtained by reacting a polyester, at least one diol and one diisocyanate,
• B) pigments and
• C) further 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 by
converting this polyester (a) together with at least one diol (b) and at least one diisocyanate (c), optionally dissolved in a solvent, to give an intermediate product containing hydroxyl end groups,
then reacting this product with at least one polyiso cyanate (d) from a triisocyanate or a diisocyanate (e) containing triisocyanate
and the polyurethane resin is converted into the predominantly aqueous phase. 2. Lacquer dispersions according to claim 1, characterized in that that the poly used to manufacture the polyurethane resin ester has a molecular weight of 300 to 2000, a hydroxyl number from 56 to 374 and an acid number from 28 to 187. 3. Lacquer dispersions according to claim 1 or 2, characterized records that the polyester is obtained by reaction min least a mono-, di- or polycarboxylic acid or more reactive  Derivatives of these acids, with one or more diols or Triplets in combination with a trifunctional component, selected from that of triols, tricarboxylic acids, dihydroxy carboxylic acids, hydroxydicarboxylic acids and hydroxysulfonic acids existing group. 4. paint dispersions according to claim 1, characterized in that the diol used for the production of polyurethane resin Has a molecular weight of 62 to 2000. 5. Lacquer dispersions according to one of claims 1 to 4, characterized draws that one chooses the amount of components a) and b) so that the equivalents of the hydroxyl groups of a) and b) 1:10 to 1: 1, preferably 1: 5 to 1: 2. 6. paint dispersions according to any one of claims 1 to 4, characterized records that the ratio of components (a + b) to c so that it selects 1.03 to 2.05, preferably 1.05 to 1.5 is. 7. paint dispersions according to any one of claims 1 to 6, characterized records that the intermediate containing hydroxyl end groups product obtained by adding component c) to a if necessary dilute in a solvent, mix the compo dents a) and b). 8. paint dispersions according to any one of claims 1 to 7, characterized ge indicates that this additional film-forming Ma materials such as melamine resins, polyester resins and / or acrylate contains resins.   9. paint dispersions according to one of claims 1 to 8, characterized ge indicates that these are preferably metal powder as pigments Aluminum powder, pearlescent pigments, color pigments or colors substances included. 10. Use of the paint dispersions according to one of claims 1 to 9 as a base coat for the production of multilayer coatings in the color processing industry, especially for painting hard surfaces. 11. Use of paint dispersions according to claim 10, in particular especially for automotive painting, as a first coat.