Two-component paint system

The invention relates to the use of a two-component existing Paint System for the production of automotive refinish coatings and coatings for plastics.

In DE-A-41 10 520, a mixed system is used for Preparing aqueous automotive refinish coatings described, which relies that Automotive Refinish by mixing a pigment-containing base color less than 5 wt.% water, with a pigment-free aqueous component are produced.

In the process described in DE-A-41 10 520, from have two components existing paint system the pigment-containing base colors unfavorable flow behavior , whereby both the metering and miscibility with pigment-free aqueous component is adversely affected. This leads, among other things to the fact that the exact setting of predetermined is complicated shades.

The the present invention is based Task is to use a two component lacquer system, the does not have the disadvantages described above.

Using one of a component (I) and a component (II) existing paint system for the production of auto repair and eating Coatings for plastic substrates, in which component (I) from<sl><li>(A) 5 to 50 wt .-% of at least one water-soluble or water-dispersible binder,</li><li>(B) 0 to 20 wt .-%. at least one crosslinking agent,</li><li>(C) from 0.5 to 60 wt .-%. at least one effect-imparting pigment,</li><li>(D) 5 to 80 wt .-% water,</li><li>(E) 0 to 40 wt .-% of at least one organic solvent,</li><li>(F) 0 to 5 wt .-% of at least one rheology-controlling additive, selected from the group of crosslinked polymeric microparticles, the inorganic Phyllosilicates and synthetic polymers containing ionic and / or more associative groups, and</li><li>(G) 0 to 10 wt .-% of at least one further conventional paint auxiliary , wherein the sum of the components (A), (B), (C), (D), (E), (F) and specified (G) percentages by weight always being 100 wt .-% results and the Component (A) consists of<ul><li>at least one water-dilutable polyurethane resin,</li><li>a mixture of at least one water-dilutable Polyurethane resin and at least one water-dilutable polyester resin,</li><li>a mixture of at least one water-dilutable Polyurethane resin and at least one water-dilutable polyacrylate or</li><li>a mixture of at least one water-dilutable Polyurethane resin, at least one water-dilutable polyester resin and at least one water-dilutable polyacrylate resin is,</li></ul>and component (II) of</li><li>(H) 70 to 99 wt .-% water</li><li>(J) 0 to 10 wt .-% of at least one organic solvent</li><li>(K) 0.1 to 10 wt .-% of at least one rheology-controlling additive according to Component (F) and</li><li>(L) 0 to 10 wt .-% of at least one further conventional paint auxiliary</li></sl>, wherein the sum of the components (H), (J), (K) and (L) specified percentages by weight always being 100 wt .-%.

The advantages of using the invention, consist of the two-component lacquer system in particular the fact that the components well are metering and mixable, whereby the preparation of Coatings with predetermined hues simply possible is. In many cases it is no longer necessary, with the prepared the coating system according to the invention Coatings in an additional operation to the processing viscosity adjust. A further advantage lies in the high freeze-thaw stability of component (I).

Suitable polyurethane resins are for example described in the following publications: EP-A-355 433    DE-A-35 45 618, DE-A-38 13 866. DE-A-32 10 051,    DE-A-26 24 442, DE-A-37 39 332, US-A-4,719,132,    EP-A-89 497, US-A-4,558,090, US-A-4,489,135,    DE-A-36 28 124, EP-A-158 099, DE-A-29 26 584,    EP-A-195 931, DE-A-33 21 180 und DE-A-40 05 961.

As the component (A) in the (I) component preferably polyurethane resins are used, the a number average molecular weight (determination: gel permeation chromatography with polystyrene as standard) 1000-30000, preferably 1500 to 20000, and an acid number of 5 to 70 mg KOH / g, preferably 10 to 30 mg KOH / g and Reacting isocyanato prepolymers with isocyanate-reactive compounds can be produced.

The preparation of prepolymers containing isocyanate groups can be prepared by reacting polyols with a Hydroxyl number 10 to 1800, preferably 50-1200 mg KOH / g, with excess polyisocyanates with Temperatures of up to 150 ° C, preferably 50 to 130 ° C, in organic solvents that do not with isocyanates can react done. The equivalent ratio of NCO to OH groups is between 2.0: 1.0 and&gt; 1.0: 1.0, preferably between 1.4: 1 and 1.1:. 1

The used for the preparation of the prepolymer Polyols of low molecular weight and / or high molecular mass be inert and anionic or forming anions enabled groups. It can low molecular weight polyols having a molecular weight from 60 up to 400, for producing the isocyanato Prepolymers are used concomitantly. In this case amounts of up to 30 wt .-% of the total Polyol constituents, preferably from about 2 to 20 Wt .-%, are used. In order to obtain an NCO-prepolymer of high flexibility, should be a high proportion of a predominantly linear Polyol having a preferred OH value of 30 to 150 mg KOH / g may be added. Up to 97 wt .-% of the total Polyol may be selected from saturated and unsaturated Polyesters and / or polyethers with a molecular weight Mn of from 400 to 5000.. The polyetherdiols selected should not apply excessive amounts introduce ether groups, since otherwise the polymers formed swell in water. are polyester by esterification of organic dicarboxylic acids produced or their anhydrides with organic diols or are derived from a hydroxycarboxylic acid or a lactone. To branched polyester produce, can to a minor extent polyols or. Polycarboxylic acids having a higher functionality will.

Als typische multifunctional Isocyanate werden aliphatic, cycloaliphatic and / or aromatic Polyisocyanates having at least two isocyanate groups used per molecule. the isomers are preferred or isomeric mixtures of organic diisocyanates. Because of their good resistance to ultraviolet Light, (cyclo) aliphatic diisocyanates Products with low Vergilbungsneigung.Die to Form the prepolymer used polyisocyanate component may also include a proportion of higher polyisocyanates included, provided that this does not causing gelation. As triisocyanates have Products proven that by trimerization or oligomerization of diisocyanates or by reaction of Diisocyanates with polyfunctional OH or NH groups Containing compounds are formed. The middle Functionality can optionally by adding Monoisocyanates be lowered.

As examples of polyisocyanates Phenylendiisocyanat, Toluylendiisocyanat, Xylylendiisocyanat, Bisphenylendiisocyanat, Naphtylendiisocyanat, Diphenylmethandiisocyanat, Isophorondiisocyanat, Cyclopentylendiisocyanat, Cyclohexylendiisocyanat, Methylcyclohexylendiisocyanat, Dicyclohexylmethandiisocyanat, Trimethylendiisocyanat, Tetramethylendiisocyanat, Pentamethylendiisocyanat, Hexamethylendiisocyanat, Propylendiisocyanat, Ethylethylendiisocyanat and trimethylhexanediisocyanate called.

Polyurethanes are generally with water tolerated, if not in their synthesis special components installed and / or special preparation steps be made. Thus, for the preparation of used the polyurethane resins compounds are the two isocyanate-reactive H-active containing groups and at least one group, which ensures dispersibility in water. Suitable Groups of this type include non-ionic groups (eg. B. Polyether), anionic groups, mixtures of these two groups or cationic groups.

For the introduction of anionic groups in the polyurethane resin molecules serve compounds containing at least one isocyanate-reactive group and at least one capable of forming anions Group. Suitable isocyanate reactive groups are in particular hydroxyl groups and primary and / or secondary amino groups. Groups capable of forming anions are, are carboxyl, sulfonic and / or phosphonic acid groups. Preferably alkanoic acids with two substituents on the α-carbon atom used. The substituent may be a hydroxyl group, be an alkyl group or an alkylol group. These Polyols have at least one, generally from 1 to 3 Carboxyl groups in the molecule. They have two to about 25, preferably 3 to 10 carbon atoms. The carboxyl groups Polyol 3 may be contained to 100 wt .-%, preferably 5 to 50 wt .-%, of the total polyol account in the NCO prepolymer.

The isocyanate groups of the isocyanato Prepolymer are with a modifier implemented. The modifying agent is preferably added in an amount such that it chain extensions and hence molecular weight increases comes. As modifiers are preferably organic compounds which Hydroxyl and / or secondary and / or primary amino groups include, in particular di-, tri- and / or higher functional polyols used. As an example of polyols which are trimethylolpropane, 1,3,4 Butantriol, Glycerin, Erythrina, Mesoerythrit, Arabs, Adonit so called. Preferably trimethylolpropane is used.

As the component (A) in the (I) component can In principle, all suitable for aqueous coatings water-soluble polyacrylate resins or water be used. Such resins are available in a large described variety and great selection commercially available. Particularly suitable polyacrylate resins described in DE-A-38 32 826 and in DE-A-38 41 540th

As the component (A) in the component (1) can Water-soluble or water-dispersible polyester resins be used.

The component (A) consists of at least minutely a water-dilutable polyurethane resin or of a mixture of at least one water-dilutable Polyurethane resin and at least one water-dilutable polyester resin and / or at least a water-dilutable polyacrylate resin.

As the component (B) in the (I) component can For example, blocked polyisocyanates and / or water soluble or dispersible amino resins be used. Preference - optionally in the presence of co-solvents - water-soluble or water-melamine resins used. These are generally etherified Melamine-formaldehyde condensation products. The water solubility or water the Amino resins depends - apart from the degree of condensation, which should be as low as possible - on the etherification from which only the lowest Members of the alcohol or ethylene glycol monoether water-soluble condensates arise. The most important have the methanol-etherified melamine resins. When using solubilizers can butanol-etherified melamine resins in aqueous phase are dispersed. It is also possible, insert carboxyl groups into the condensate. Transetherification highly etherified formaldehyde condensates with oxycarboxylic are their carboxyl groups, water soluble after neutralization.

The component (I) can be used as component (C) all conventional lacquer effect pigments, which do not react with water or do not dissolve in water, included. pigments may consist of inorganic or organic compounds consist.

Effect pigments which can include metal flake pigments such as commercial aluminum bronzes, according to DE-A-36 36 183 chromated aluminum bronzes, and commercial Stainless steel bronzes, and also nonmetallic Effect pigments, such as pearlescent pigments and interference pigments, be used.

As constituent (E), the component (I), at least an organic solvents. Examples suitable solvents are in particular water-miscible Solvents, such as alcohols, esters, ketones, etc. keto esters, glycol ether esters Preference are alcohols and glycol ethers, particularly preferably Butyl glycol and butanols.

As component (F), the component (I), at least one rheology control additive contained. As rheology control additives are used: networked polymeric microparticles, such as, for example, in EP-A-38 127 discloses inorganic Phyllosilicates such as aluminum-magnesium silicates, Sodium magnesium phyllosilicates and sodium magnesium fluorine lithium phyllosilicates of the montmorillonite type, and synthetic polymers having ionic and / or associative groups such as polyvinyl alcohol, Poly (meth) acrylamide, poly (meth) acrylic acid, Polyvinylpyrrolidone, styrene-maleic anhydride or Ethylene-maleic anhydride copolymers and their derivatives or else hydrophobically modified ethoxylated Urethanes or polyacrylates. Preferred rheology control additives inorganic phyllosilicates used. Particularly preferred is a combination of a carboxyl-containing polyacrylate with an acid number of 60-780, preferably 200 to 500 mg KOH / g and a sodium magnesium phyllosilicate used as a rheology control additive.

The sodium magnesium phyllosilicate expediently in the form of an aqueous paste in the varnish component incorporated. The paste contains preferably 3 wt .-% phyllosilicate and 3 wt .-% Polypropylene glycol, or 2 wt .-% layered silicate and 0.6 wt .-% polypropylene glycol, or 2 wt .-% phyllosilicate and 2 wt .-% of other commercial surfactants Substances, all percentages are based on the total weight of the paste. The Component (I) of the coating system according to the invention should preferably not rheology control additive, in particular no inorganic layer silicate as rheologiesteuemdes additive contained. The for with prepared the coating system according to the invention Varnishes necessary rheologiesteuemden additives should preferably exclusively in component (II) be included. It is particularly preferred that in the Cases where an inorganic layer silicate as rheology control additive is employed, the inorganic Phyllosilicate exclusively in the paint component (II) is contained.

The component (I) may also component (F) as the component (G) at least one more conventional Paint Additive included. Examples of such additives are defoamers, dispersing, emulsifying, and flow control agents.

The preparation of component (I) are prepared by known in the art methods by mixing and if desired, dispersing the individual constituents.

The incorporation of the effect pigments is usually by homogeneously mixing of effect pigments with one or more solvents. This mixture is then in a mixture of one or more the above-described binder, optionally with the addition of further organic solvents, by means of a Stirrer or dissolver stirred.

The components (J), (K) and (L) of the varnish component (II) correspond to the constituent (E), (F) and (G) of the paint component (I).

The coating system according to the invention is for manufacturing aqueous coatings which have a precisely defined should have color, suitable. By mixing correspondingly pigmented coating components (I) in the necessary achievement of corresponding colors Proportions and adding the coating component (II) can shade accurate, immediately processable aqueous coatings are obtained. The ertindungsgemäße Paint system is particularly useful for mixing systems Production of automotive refinish coatings (see eg. B. Glasurit Handbook, 11th Edition, Kurt R., Vincentz-Verlag, Hanover 1984, pages 544 to 547 suitable). With the invention Paint system can of course also paints for other applications such. B the coating of plastics or Serienlakkierung be made of motor vehicle bodies.

In the following the invention will anband of embodiments explained in more detail. Statements on Parts and percentages are by weight, is if not expressly stated otherwise.

1. Preparation of an organic polyurethane resin solution

In a suitable reaction vessel with stirrer, Reflux condenser and feed vessel under a protective gas 686.3 g of a polyester having a number average Molecular weight of 1400 based on a commercially available unsaturated dimer fatty acid (having an iodine value 10 mg of J₂/ G, a monomer content of at most 0.1%, a trimer content of not more than 2%, a Acid number of 195-200 mgKOH / g and a saponification number 197-202 mgKOH / g), isophthalic acid submitted and hexane and successively with 10.8 g Hexanediol, 55.9 g of dimethylolpropionic acid, 344.9 g of methyl ethyl ketone and 303.6 g of 4,4'-di- (isocyanatocyclohexyl) methane added. This mixture is so long Refluxed until the isocyanate content to 1.0 % Has dropped. Then the mixture is 26.7 g of trimethylolpropane are added and up to a Viscosity of 12 dPas (at a partial dissolution of a Part resin solution in a portion of N-methylpyrrolidone) under Refluxed. Then, 1378.7 g butyl glycol added. After vacuum distillation, in which the Methyl ethyl ketone is removed, the resin solution with 32.7 g dimethylethanolamine neutralized. The solids content the resulting resin solution is 44% .Among intensive stirring is stopped by adding butylglycol to a solids content of 41 wt.% diluted.

2. Preparation of an aqueous polyurethane resin dispersion

In a suitable reaction vessel with stirrer, Reflux condenser and feed vessel under a protective gas 686.3 g of a polyester having a number average Molecular weight of 1400 based on a commercially available unsaturated dimer fatty acid (having an iodine value 10 MGJ₂/ G, a monomer content of at most 0.1 %, A trimer content of not more than 2%, an acid number 195-200 mgKOH / g and a saponification number 197-202 mgKOH / g), isophthalic acid and submitted hexane and successively with 10.8 g of hexane, 55.9 g of dimethylolpropionic acid, 344.9 g of methyl ethyl ketone and 303.6 4,4-di- (isocyanato) methane were added. This mixture is so long Refluxed until the isocyanate content to 1.0% has dropped. Then the mixture is 26.7 g of trimethylolpropane are added and up to a Viscosity of 12 dPas (at a partial dissolution of a Part resin solution in a portion of N-methylpyrrolidone) under Refluxed. By adding 47.7 g of butyl glycol is possibly present excess isocyanate destroyed. Then the reaction mixture 32,7 g Dimethylethanolamin, 2688,3 g entionisiertes Water and 193.0 g of butyl glycol under vigorous Stirring. After removing the methyl ethyl ketone by vacuum distillation one obtains a aqueous dispersion having a solids content of about 27%.

3. Preparation of pigment pastes

containing 3.1 preparing a Aluminiumpignent Pigmentpaste

chromated 15.5 parts of according to DE-OS 36 36 183 Aluminiumbronze (Aluminiumgehalt 65%, are average particle diameter 15 microns) homogeneously butyl glycol by stirring for 15 minutes in 14 parts and then distributed to a mixture of 51 parts in accordance with point 1. polyurethane resin solution prepared, 19.5 parts of a commercial, methanolveretherten Melaminharzes (75 %ig in iso-Butanol) and 10 parts of butyl glycol incorporated with stirring calmly. This mixture is further 30 minutes with a high speed at 1000 rev / min stirring.

3.2 Preparation of a pigment paste as compared blaupigmentierten

7 parts Paliogenblau, 57 parts of according to point 1 above. prepared polyurethane resin solution, 15 parts of butyl glycol and 21 parts of a commercial methanol-, Melaminharzes (75%igen in iso-Butanol) are mixed with stirring in a sand mill and dispersed.

4.1 Preparation of component (I)

30 parts of the pigment paste prepared in accordance with section 3.1 are mixed with 40 parts of the under step 2. prepared aqueous polyurethane resin dispersion and 30 parts of deionized water mixed well. The on thus obtained component (I) is easily dosed, with different color pigmented components (I) as as the component of test 4.2 (see. below) highly miscible and has an excellent storage stability.

4.2 Preparation of a different color pigment (comparison) component

30 parts of the pigment paste prepared in accordance with section 3.2 are mixed with 40 parts of the under step 2. prepared aqueous polyurethane resin dispersion and 30 parts of deionized water mixed well.

5. Preparation of a component according to the invention (II)

To 57.5 parts of a pre-swollen aqueous paste, containing 3 wt .-% of an inorganic sodium magnesium phyllosilicate thickener and 3 Wt .-% polypropylene glycol having a number average Molecular weight of 900, the percentages are based on the total weight of the paste, be 35.5 parts of deionized water, 1.5 parts of butyl glycol, 0.5 parts of a commercial defoamer and 5 parts of a 3.5% solution of a commercial Polyacrylatverdickers added in water while stirring. The component (II) thus prepared is in accordance with the Point 4.1 manufactured components (I) highly miscible and has excellent Storage stability.