DE10009414A1 - Binding agent mixture for aqueous stoved coating compositions for filler layers for automobile body parts comprises blocked polyisocyanates dispersed in water and polyhydroxyl compounds. - Google Patents

Abstract

A binding agent mixture for aqueous stoved coating compositions comprises (A) blocked polyisocyanates dispersed in water (B) water soluble or dispersible polyhydroxyl compounds such that component (A) has a dispersed particle size of 0.05-10(0.1-5), preferably 0.2-1.5 mu m following preparation by a direct dispersion process or phase transfer process using a high efficiency dispersion apparatus. A binding agent mixture (I) for aqueous stoved coating compositions (II) comprise (A) blocked polyisocyanates dispersed in water (B) water soluble or dispersible polyhydroxyl compounds (C) optionally water soluble or dispersible cross-linking resins and (D) optionally other water soluble or diseprsible substances whereby (A) comprises (A1) 40-80 wt.% of a polyisocyanate component (A2) 10-40 wt.% of a monofunctional blocking agent for isocyanate groups (for isocyanate addition reactions) (A3) 1-30 wt.% of a hydrophilic agent (A4) optionally further cross-linking substances and (A5) optionally conventional additives such that component (A) has a dispersed particle size of 0.05-10(0.1-5), preferably 0.2-1.5 mu m following preparation by a direct dispersion process or phase transfer process using a high efficiency dispersion apparatus.

Description

The present invention relates to novel aqueous coating compositions for stoving coatings, in particular for the production of hard, elastic, solid bodies rich fillers with very good stone chip protection and their use for Coating of metals, plastics, wood and glass.

The importance of water-based paints and coatings has increased in recent years due to ever stricter emission guidelines with regard to the Lackappli cation released solvent strongly. Although already for many Areas of application aqueous coating systems are available, they can high quality level of conventional, solvent-based paints with regard to solvent medium and chemical resistance or elasticity and mechanical Often not fully able to withstand stress. So far, in particular no coating agents to be processed from the aqueous phase Known polyurethane base, which meet the high demands of practice on hard Simultaneously elastic filler with a high solids content for coating Automotive bodies with regard to film hardness, impact strength, stone chips Resistance as well as water and chemical resistance are completely sufficient.

This statement applies to both GB-A 1 444 933, EP-A 0 061 628 and DE-A 23 59 613, which deals with the hydrophilic modification of aromatic Deal with polyisocyanates, as well as for DE-A 40 01 783, which deals with special deals with anionically modified aliphatic polyisocyanates, as well as for the Systems of DE-A 24 56 469, DE-A 28 14 815, EP-A 0 012 348 and EP A 0 424 697 which blocked with aqueous stoving binders Deal with polyisocyanates and organic polyhydroxyl compounds. Also the Systems based on carboxyl group-containing polyurethane prepolymers blocked isocyanate groups according to DE-A 27 08 611 or the blocked, water soluble urethane prepolymers according to DE-A 32 34 590 are for the above Area of application largely unusable. Significant progress in elasticity  and solvent, water and chemical resistance are with the systems of DE-A 42 21 924, the combinations of special, blocked, water-soluble or dispersible polyisocyanate mixtures and special water-soluble ones or describes dispersible polyhydroxyl compounds. Further Improvements in the required baking temperature and reactivity stoving lacquers can be achieved when water-thinnable or in water Use dispersible polyisocyanate crosslinkers with pyrazoles as blocking agents det be such. B. described in WO 97/12924 and EP-A 0 802 210.

The solids content including binders, crosslinkers, additives, pigments and Fillers, this described and some are in practical use aqueous filler is generally between 47 and 50, maximum 53% by weight. In this context, however, is desirable much higher solids content to increase the order efficiency at Appli cation to improve significantly. Furthermore, a much higher hardness for a required better grindability of the filler, while at the same time having good elasticity properties should guarantee a high level of stone chip protection.

As has now been found, surprisingly, it is possible to produce stoving fillers to be processed from the aqueous phase which, in addition to the requirements previously fulfilled in practice, have a higher solids content and, after stoving, give coatings with very high hardness but at the same time very good stone chip protection properties, if selected combinations of the type described in more detail below are used as binders. The stoving enamels according to the invention consist of:

• A) special blocked polyisocyanates dispersed in water,
• B) polyhydroxyl compounds which are soluble or dispersible in water,
• C) optionally water-soluble or dispersible crosslinking resins and  
• D) optionally other water-soluble or dispersible substances.

By using these new binder mixtures according to the invention in aqueous stoving lacquers can achieve very high solids contents. Consequently there is an increase in order efficiency and productivity. At Fülleran Applications are obtained coatings in which the hardness and thus the Sandability as well as the top coat level compared to the state of the art are significantly improved.

The invention relates to binder mixtures for aqueous stoving enamels composed of:

• A) special blocked polyisocyanates dispersed in water,
• B) polyhydroxyl compounds which are soluble or dispersible in water,
• C) optionally water-soluble or dispersible crosslinking resins and
• D) optionally further water-soluble or dispersible substances,

characterized in that component I)

• A) 40 to 80% by weight of one or more polyisocyanate components,
• B) 10 to 40% by weight of one or more in the sense of isocyanate addition reaction of monofunctional blocking agents for isocyanate groups,
• C) 1 to 30% by weight of one or more hydrophilizing agents,
• D) optionally further crosslinking substances and  
• E) there are any customary additives,

with the proviso that component I) either after a direct dispersion process or according to the phase reversal process by means of a dispersing device was produced with a high volume-based dispersion capacity and a medium Particle size of the dispersion particles from 0.05 to 10 microns, preferably 0.1 to 5 µm, in particular 0.15 to 2.5 µm and particularly preferably 0.2 to 1.5 µm Has particle diameter.

For the preparation of the dispersions I) essential to the invention by dispersing processes arrive at dispersing devices with high volume-related dispersing performance, such as B. pressure relief homogenizing nozzles for use.

Corresponding dispersing machines are e.g. B. from Formation of Emulsions, in P. Beche, Encyclopedia of Emulsion Technology, Vol. 1, New York, Basel, Decker 1983 known, but were used for the production of such aqueous dispersions for aqueous burn-in fillers have not yet been used.

Dispersing machines are based on the size of the volume-related output chosen. For the production of finely divided dispersions (approx. 1 µm particle diameter knives) dispersing machines with high volume-related outputs are required derlich, z. B. high pressure homogenizers. So with rotor / stator machines no longer produce finely divided dispersions. In the case of EP-A 0 101 007 described jet disperser is a special pressure release nozzle, which is much more efficient than high-pressure homogenis sators. Already at 50 bar homogenization pressure with the jet disperser Particle size distributions achieved for the high pressure homogenizer 200 bar required.

The jet disperser as a dispersing device can be particularly advantageous Produce finely divided dispersions, both continuously and discontinuously.  

According to the invention, the aqueous dispersion can also be reversed from one phase Water-in-oil emulsion can be converted into an oil-in-water emulsion.

The inventive aqueous dispersions essential to the invention I) can in combination with components II), III) and optionally IV) Stove enamel can be used on any heat-resistant substrates, e.g. B. as a filler, basecoat or topcoat for the production of single-layer and / or Multicoat paint systems, for example in the automotive sector. The before drawn use is in the filler area.

Component A) of dispersion I) essential to the invention is aliphatic and / or cycloaliphatic biuret, isocyanurate, urethane, uretdione, Polyisocyanates containing allophanate and / or iminooxadiazinedione groups. It can also any mixtures of different polyisocyanates and polyiso cyanates containing several of the groupings mentioned can be used. For The polyisocyanates can be prepared using the known aliphatic and / or cyclo aliphatic diisocyanates are used, from which the polyisocyanates known methods such. B. trimerization, allophanatization, urethanization, Biuretization. 1,6-Diiso are preferably used cyanatohexane (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (Isophorone diisocyanate, IPDI), 2,4- and / or 2,6-diisocyanato-1-methylcyclohexane and 4,4'-diisocyanatodicyclohexylmethane (®Desmodur W, Bayer AG). Prefers are used to produce component A) isocyanurate, biuret and / or urethane group-containing polyisocyanates based on 1,6-diisocyanatohexane, isopho rondiisocyanate and ®Desmodur W are used.

The known monofunctional blocking can be used as blocking agent B) medium, such as B. malonic acid esters, acetoacetic acid esters, lactams, oximes, pyrazoles, Triazoles, imidazoles, amines or any mixtures of these classes of compounds, be used. Blocking agents which are in the temperature range are preferably used  split off up to 180 ° C, especially up to 160 ° C. Are preferred Butanone oxime, cyclohexanone oxime and / or 3,5-dimethylpyrazole.

Internal emulsifiers and external emulsifiers are used as hydrophilizing agents C) or any mixtures of these compounds.

Nonionic ethylene oxide units are found as internal emulsifiers hydrophilic structural components and / or (potentially) containing carboxyl groups anionic structural components use.

The nonionic hydrophilic structural components are Compounds that react one or two per molecule with respect to isocyanate groups capable groups, especially hydroxyl groups. The polyether chains at least 50% by weight of these compounds, preferably to 100 wt .-% of ethylene oxide units, in addition to these, the Aus made accordingly, propylene oxide units can also be present. Suitable such nonionic hydrophilic structural components are, for example, mono functional polyethylene glycol monoalkyl ethers with molecular weights from 350 to 3000. The molecular weight is preferably between 500 and 1000.

Compound with at least serve as (potentially) anionic structural components a group which is reactive towards isocyanate groups. Preferably acts these compounds are at least one, preferably one or two Carboxylic acids containing hydroxyl groups or salts of such hydroxy carboxylic acids. Suitable acids of this type are, for example, 2,2-bis (hydroxy methyl) alkane carboxylic acids such as dimethylol acetic acid, 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid or 2,2-dimethylol pentanoic acid, dihydroxy amber acid, hydroxypivalic acid or mixtures of such acids. Particularly preferred Dimethylolpropionic acid and / or hydroxypivalic acid are used. The free acid groups, especially carboxyl groups, represent the above ten "potentially anionic" groups, while those by neutralization  salt-like groups obtained with bases, in particular carboxylate groups, are the "anionic" groups mentioned above. For the solution or dispersion in water is an at least partial neutralization of the Carboxyl groups necessary. Generally the carboxyl groups become least neutralized to 50%, possibly with an excess of neutra lizing agent can be used.

Usual emulsifiers or dispersing agents such as those used as external emulsifiers e.g. B. by Johann Bielmann in paint additives, WILEY-VCH Verlag GmbH Weinheim, New York, Chichester, Brisbane, Singapore, Toronto 1998, pp. 87-92 are used. Particularly suitable substances are, for example Addition products of ethylene oxide and optionally propylene oxide with hydro phobic starter molecules such as B. nonylphenol, phenol / styrene condensates and long chain, optionally branched, alcohols, such as lauryl alcohol or stearyl alcohol. Ionic compounds of this type, such as ethylene oxide and optionally sulfur or phosphorus containing propylene oxide units acid ester salts, such as. B. described in WO 97/31960, are suitable.

In the case of the additional crosslinker component that may be used D) are substances that are produced by chemical reaction with the hydroxyl Groups of component II) for curing the coatings of the invention to lead. Examples include aminoplast resins, e.g. B. corresponding melamine Derivatives such as alkoxylated melamine resins or melamine-formaldehyde condensates tion products (e.g. FR-A 943 411, "The Chemistry of Organic Filmformers", pages 235-240, John Wiley & Sons Inc., New York 1974) and conventional crosslinking agents, e.g. B. epoxy reactive with alcoholic hydroxyl groups, carboxylic acid anhydrides, phenolic resins, resol resins, urea resins or guanidine resins or their mixtures.

In the case of the customary additives E) which may be used it is for example neutralizing agents, catalysts, auxiliaries  and / or additives, such as. B. wetting agents, degassing agents, anti-settling agents, Leveling agents, radical scavengers, antioxidants, UV absorbers, thickeners, low Shares in solvents and biocides.

The dispersion I) essential to the invention is prepared in several stages, with the proportions of the reactants are chosen so that the equiva lent ratio of isocyanate groups of component A) to isocyanate groups reactive groups of component B) and optionally C) 1: 0.5 to 1: 2, preferably 1: 0.8 to 1: 1.2 and particularly preferably 1: 0.9 to 1: 1 lies.

If internal emulsifiers are used as component C) are opposite Isocyanate groups reactive hydroxyl groups. Here are used to manufacture the dispersion I) essential to the invention, the quantitative ratios of the reactants be chosen so that the equivalent ratio of isocyanate groups of the compo nente A) to groups of the compo which are reactive toward isocyanate groups B) and C) at 1: 0.5 to 1: 2, preferably at 1: 0.8 to 1: 1.2 and particularly is preferably 1: 0.9 to 1: 1.

When using nonionically hydrophilic structural components, the amount of component C) is measured such that in the dispersion I) obtained according to the invention, 0.1 to 10% by weight, preferably 0.5 to 5% by weight, of within final and / or laterally arranged polyether chains, built-in ethylene oxide units (calculated as C ₂ H ₄ O, molecular weight = 44) are present.

When using (potentially) anionic structural components, the com component C) is used in such a quantity that in the invention obtained essential dispersion I) 0.1 to 5% by weight, preferably 0.5 to 1.5% by weight chemically fixed carboxyl groups (calculated as COOH, molecular weight = 45) available.  

If external emulsifiers are used as component C), there are none groups reactive towards isocyanate groups. Here are the Production of the dispersion I) essential to the invention, the proportions of Rection partners chosen so that the equivalent ratio of isocyanate groups Component A) to groups which are reactive toward isocyanate groups Component B) is 1: 0.8 to 1: 1.2, preferably 1: 0.9 to 1: 1. The Amount of external emugators C) related to the total amount of the compo components A), B) and C) is 1 to 10% by weight, preferably 3 to 7% by weight and particularly preferably 4 to 6% by weight.

To produce component I), polyisocyanate A) is used in any Order or simultaneously with the blocking agent B) and optionally an internal hydrophilizing agent C) in the NCO / OH equiva given above lent relationship implemented. If no internal hydrophilizing agent is used, takes place before, during or after the reaction of components A) and B) in the above specified NCO / OH equivalent ratio admixing an external emul gators C) in the quantitative ratio indicated above.

The reactions usually take place in a temperature range from 20 to 140 ° C, preferably at 70 to 120 ° C, especially the reaction with (potentially) anionic structural components C) under mild conditions is carried out in order to prevent the carboxyl group from interfering with the Isocya nat groups reacted.

The reactions can be carried out solvent-free or in an inert solvent be performed. The reaction in such inert solvents is preferred after the emulsification step by vacuum distillation completely or partially the aqueous phase of a dispersion can be removed. Named as an example be ketones such as acetone and methyl ethyl ketone and esters such as ethyl acetate and Butyl acetate and aromatics such as toluene and xylene. The is particularly preferred Implementation in methyl ethyl ketone.  

After the reaction has ended, if a hydrophilization with a (potentially) anionic structural component C) has taken place, at least partially Neutralization of the built-in carboxyl groups. The addition of this is required The neutralizing agent can be used before, during or after the dispersing step respectively. Suitable bases are ammonia, amines, such as. B. N-methyl morpholine, dimethylisopropanolamine, triethylamine, N, N-dimethylethanolamine, Methyldiethanolamine, triethanolamine, morpholine, tripropylamine, triisopropylamine, 2-diethylamino-2-methyl-1-propanol or mixtures of these and other neutra agent. Also suitable, but less preferred than neutralization medium are alkali or Erdallcalihydroxyde, such as. B. sodium hydroxide, lithium hydroxide or potassium hydroxide. The preferred neutralizing agent is N, N- Dimethylethanolamine.

To prepare the aqueous suspension, the organic solution of the reaction product from components A), B) and optionally C) is mixed with water. This is done either by the direct dispersion process, in which the organic phase is dispersed in the aqueous phase, or by the reverse phase process, in which a water-in-oil emulsion which is initially present is converted into an oil-in-water emulsion. This is done with the aid of a dispersing device with a high volume-based dispersing capacity. It can be z. B. are cage stirrer, dissolver, rotor / stator mixer, Druckent voltage nozzles, preferably jet dispersers, the volumetric dispersing power for the dispersing process being 1 to 10 ⁸ W / cm ³ , preferably 1 to 5. 10 ⁷ W / cm ³ and particularly preferably 1 to 3. 10 ⁷ W / cm ³ . The average particle size of the particles of the aqueous dispersion or suspension is 0.05 to 10 μm, preferably 0.1 to 5 μm, in particular 0.15 to 2.5 μm and particularly preferably 0.2 to 1.5 μm. In order to obtain special particle size distributions, it makes sense to disperse in several stages with a defined volume-related performance.

It has proven to be advantageous before the dispersion process by the Jet disperser first a pre-emulsion using a stirrer or dissolver to produce and then feed this pre-emulsion to the jet disperser. In the Such a quantity of water is used to prepare the dispersions or emulsions used that 20 to 75 wt .-%, preferably 30 to 70 wt .-% and 35 to 70% by weight dispersions or emulsions of the Binding agents I) essential to the invention result. After what finished In addition, the solvent is removed by distillation, preferably in vacuo.

The dispersion can be in a wide temperature range at both lower Temperature, such as B. 10 ° C, as well as at a higher temperature to well above the Melting point of the polymer mixture, such as. B. 150 ° C take place. At such high Temperatures are only a short one due to the reactivity of the binder systems timely temperature exposure in the seconds range possible.

Any other crosslinking substances D) and the usual additives E) can the organic solution of the reaction product from components A), B) and optionally C) before the dispersion be added. In the case of water-soluble or dispersible substances D) and E) this can also be done after the dispersion and distillation of the aqueous Phase are added.

The polyhydroxyl component II) is, for example, in water soluble or dispersible polyhydroxyl compounds by gel permeation tion chromatography (standard polystyrene) determinable number average ler molecular weight Mn from 1000 to 100000, preferably 2000 to 50,000, of the type known per se from the chemistry of polyurethane coatings, provided that Polyhydroxyl compounds have a solubility or dispersibility sufficient water content of hydrophilic groups, in particular Polyether chains containing carboxylate groups and / or ethylene oxide units. In principle, however, the use of on its own is not possible  sufficient hydrophilic polyhydroxyl compounds mixed with external ones Emulsifiers.

Possible component II) are polyhydroxy polyesters and polyhydroxy poly ethers, polyhydroxypolyurethanes, polyhydroxycarbonates, urethane-modified poly ester polyols, urethane modified polyether polyols, urethane modified polycarbo polymers containing nat polyols or hydroxyl groups, d. H. the in itself known polyhydroxy polyacrylates. However, mixtures of these can also be used mentioned polyhydroxy compounds, or prepared in situ, if necessary grafted, representatives of combinations of these polyhydroxyl compounds, such as. B. Polyester polyacrylate polyols, polyether polyacrylate polyols, polyurethane polyacrylics lat polyols, polyester polyurethanes, polyether polyurethanes, polycarbonate polyurethanes and polyether polyester or mixtures thereof as component II) are used come.

The polyacrylate polyols are known copolymers of simple esters of acrylic and / or methacrylic acid, for the purpose of introduction the hydroxyl groups hydroxyalkyl esters such as 2-hydroxyethyl, 2- Hydroxypropyl, 2-, 3-, or 4-hydroxybutyl esters of these acids are also used become. For the introduction of carboxyl groups, which are to be converted into Carboxylate groups can be neutralized with amines, z. B. acrylic and / or methacrylic acid. Other possible comonomers are olefinic unsaturated compounds into consideration, such as. B. vinyl aromatics, acrylonitrile, Maleic acid di (cyclo) alkyl esters, vinyl esters, vinyl ethers and the like. s. w ..

The polymers can on the one hand directly in water with the aid of Emulsifiers are produced, which form emulsion copolymers, which also "Primary dispersions" are called. On the other hand, the production is in organic solvents and, after the introduction of ionic groups, subsequent ones Conversion into the aqueous phase possible, so-called "secondary dispersions "can be obtained.  

Suitable polyether polyols are those known per se from polyurethane chemistry Ethoxylation and / or propoxylation products of suitable 2- to 6-valent Starter molecules such as B. water, ethylene glycol, propanediol, trimethylolpropane, Glycerin, pentaerythritol and / or sorbitol.

Examples of suitable polyester polyols are in particular those in polyurethane Chemically known reaction products of polyhydric alcohols, for example of alkane polyols of the type just mentioned by way of example inferior amounts of polycarboxylic acids or polycarboxylic anhydrides, in particular special dicarboxylic acids or dicarboxylic acid anhydrides. Suitable polycarbonate Acids or polycarboxylic anhydrides are, for example, adipic acid, phthalic acid, Isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydro phthalic anhydride, maleic acid, maleic anhydride, their Diels-Alder adducts with cyclopentadiene, fumaric acid or dimeric or trimeric fatty acids. To special Setting molecular weights or functionalities of the polyester polyols also exists the possibility of using monofunctional alcohols, such as. B. 2- Ethylhexanol or cyclohexanol and / or monofunctional carboxylic acids, such as. B. 2-ethylhexanoic acid, benzoic acid or cyclohexane carboxylic acid. At the Her position of the polyester polyols can of course be any mixtures of mono- and polyfunctional alcohols or any mixtures of mono- and polyfunctional carboxylic acids or carboxylic anhydrides are used.

The polyester polyols are prepared by known methods, such as, for. B. in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 2, G. Thieme- Verlag, Stuttgart, 1963, pages 1 to 47 are described.

The hydrophilic modification of these polyester polyols which may be required is carried out according to methods known per se, such as, for example, in EP-A 0 157 291 or EP-A 0 427 028. The described in these publications level, water-soluble or dispersible, urethane-modified polyesters  particularly suitable according to the invention as component II). Particularly preferred as Component II) come into consideration urethane-modified polyester resins, as in DE-A 42 21 924 are described. Also suitable, but less preferred, are those described in DE-A 38 29 587, water-soluble or dispersed hydroxyl-containing polyacrylates.

The polyfunctional crosslinking resins III) are either water-soluble or dispersible blocked polyisocyanates as well as water-soluble or dispersed gable amino resins, such as. B. melamine or urea resins. Prince The water-soluble or dispersible polyisocyanates are particularly suitable, such as they have already been mentioned in the prior art. Are particularly suitable however, the water-soluble or dispersible blocked polyisocyanates which are described in DE-A 42 21 924 and DE-A 198 10 660.

It is also possible to use already finished mixtures of representatives of components II) and III) as a combination partner for component I) essential to the invention use. Such finished mixtures are due to their good stock stability at room temperature already in practice.

For example, epoxy can be used as further water-dispersible substances IV) resins, phenolic resins, polyamine resins, low molecular weight epoxy crosslinkers and low molecular polyamine crosslinkers are used.

For the production of ready-to-use coating agents, especially fillers, the special dispersions I) essential to the invention with the polyhydroxyl compounds II), where appropriate the crosslinkers III) and, if appropriate, representatives of component IV) mixed. The mixing ratio with respect to the compo Nenten I) to III) is in the range of 50: 45: 5 to 5: 45: 50 wt .-%, preferably 45: 45: 10 to 10: 45: 45% by weight and particularly preferably 40: 45: 15 to 15: 45: 40% by weight based on the solid. Representatives of component IV) can optionally in proportions of up to 20% by weight, preferably 10% by weight, based on  the solid, are used. Only mixtures are particularly preferred of components I) and II) and optionally III) used. The so obtained One-component binders can generally be stored for any length of time. If necessary, auxiliary materials and additives from the coating tion technology, such as pigments, fillers, leveling agents, wetting agents and Dispersing agents, anti-blistering agents, catalysts and the like. Like. can aqueous binder or binder mixture and / or the individual components I), II) and optionally III) and IV) are added. Is of particular advantage it, the individual components I), II) and optionally III) and IV) or I) and the Mixture of II) and optionally III) with auxiliaries, pigments and fillers to process ready-to-use pastes, which can then be used within the above mentioned limits can be mixed together. Let it this way achieve very special properties for special requirements. It exists also the possibility of some additives, such as. B. leveling agents or catalysts, add component I) before it is dispersed in water.

The one-component Be containing the dispersions I) essential to the invention Layering agents can be applied by any coating method technology such as B. spraying, brushing, dipping, flooding or with the help of rollers and doctor blades, on any heat-resistant substrates single or multi-layer be applied.

For example, coatings on metal, plastic, wood or glass are obtained Curing the paint film at 80 to 220 ° C, preferably 100 to 200 ° C and particularly preferably 120 to 180 ° C.

The binders according to the invention are preferably suitable for the production of Coatings and paints on steel sheets, such as those used for manufacturing Position of vehicle bodies, machines, cladding, barrels or containers use. They are preferably used for the production of  Automotive sensors. The paint films generally have a dry layer thickness from 0.01 to 0.3 mm.

The binders according to the invention result in long-lasting surfaces protection, as demonstrated in the examples. Especially the surprisingly high one Stone chip resistance combined with high film hardness, which is in contrast Characteristics are to be emphasized. This makes the binders for Applications where a good stone chip protection paired with a high Lacquer film hardness is required, suitable in an excellent manner.

The special advantage of the new aqueous binders is in addition to their high Stability when stored both at room temperature and slightly elevated Temperatures from 30 to 60 ° C the particularly high solids content of ≧ 55% by weight, which is generally not the case with previously known aqueous binders is not achieved is achieved.

The following examples illustrate the invention, but without it restrict.  

Examples

Unless otherwise stated, all percentages relate to the weight.

example 1 Production or description of the starting materials 1.1. Polyisocyanate component A1)

In a 2 l four-necked flask with stirrer, gas inlet tube, internal thermometer, Dropping funnel and reflux condenser, 1332 g of isophorone diisocyanate (IPDI) under Nitrogen submitted and heated to 80 ° C. Become a dropping funnel 15 ml of a 5% strength by weight solution of 2-hydroxy within 45 minutes propyltrimethylammonium hydroxide in 2-ethyl-1,3-hexanediol / methanol (6: 1, wt. Parts) added slowly and evenly. The temperature rises to 88 ° C (90 ° C should not be exceeded because the trimerization is too high Temperatures are non-specific and lead to higher viscosities of the end product leads). After the dropping has ended, the mixture is stirred at 80 ° C. until the Reaction mixture has reached an NCO content of 30.6%. Then you stop by adding 0.36 g (70 ppm molar) of a 25% solution of dibutyl phosphate in IPDI. Excess monomeric IPDI is removed by thin film distillation removed. An almost colorless, clear resin is obtained with a yield of 44%, which is 70% dissolved in methyl ethyl ketone. The viscosity of the solution at 23 ° C is 300 mPa.s, the isocyanate content is 11.8% and the content of free, monomeric IPDI is 0.18%.

1.2. Polyisocyanate component A2)

®Desmodur N 3300 (Bayer AG), solids content: 100%; Viscosity at 23 ° C: 3500 mPa.s; Isocyanate content: 21.8%.  

Example 2 Production of Dispersions I) Essential to the Invention 2.1. Dispersion I.1)

355.93 g of polyisocyanate component A1) are placed in a 1 liter four-necked flask equipped with a stirrer, internal thermometer and reflux condenser, dissolved in 411.15 g of methyl ethyl ketone and heated to 60.degree. Then 96.13 g of 3,5-dimethyl pyrazole are added in portions with stirring. The reaction mixture is stirred at 60 ° C. until no isocyanate band can be seen in the IR spectrum. Then 11.51 g of emulsifier WN (emulsifying aid, Bayer AG) and 5.18 g of ®Synperonic PE / F 127 (emulsifying aid, company ICI) are added and a homogeneous mixture of the components is prepared by stirring. A water-in-oil emulsion is produced from this solution by intensive mixing with 359.67 g of water using a dissolver, which is then phase-reversed into an oil-in by passage through a jet disperser at elevated pressure (10 bar) according to EP 0101007 -Water emulsion experiences. The methyl ethyl ketone is distilled off in vacuo. The dispersion is then filtered through a filter with a mesh size of 10 µm. The result is a product with the following characteristics:
Flow time (ISO 4 cup, 23 ° C): 10 s
Solids content: 50.3% by weight
average particle size: 0.42 µm (laser correlation spectroscopy)
blocked NCO content: 11.64% (calculated, based on the solid)

2.2. Dispersion I.2)

192.66 g of polyisocyanate component A2) are placed in a 1 liter four-necked flask with stirrer, internal thermometer and reflux condenser, dissolved in 419.67 g of methyl ethyl ketone and heated to 60.degree. Then 87.12 g of butanone oxime are added in portions with stirring. The reaction mixture is stirred at 60 ° C. until no isocyanate band can be seen in the IR spectrum. Then 14.90 g of Rhodafac PA 17 (emulsifying aid, Rhodia) and 1.20 g of the neutralizing agent triethylamine are added and a homogeneous mixture of the components is prepared by stirring. A water-in-oil emulsion is prepared from this solution by intensive mixing with 195.25 g of water using a dissolver, which is then phase-reversed into an oil by passage through a jet disperser at elevated pressure (1 bar) according to EP 0101007 experienced in water emulsion. The methyl ethyl ketone is distilled off in vacuo. The dispersion is then filtered through a filter with a mesh size of 10 µm. The result is a product with the following characteristics:
Flow time (ISO 4 cup, 23 ° C): 23 s
Solids content: 60.0% by weight
average particle size: 0.36 µm (laser correlation spectroscopy)
blocked NCO content: 14.25% (calculated, based on the solid)

2.3. Dispersion I.3)

177.96 g of polyisocyanate component A1) and 96.33 g of polyisocyanate component A2) are placed in a 1 liter four-necked flask with stirrer, internal thermometer and reflux condenser, dissolved in 447.72 g of methyl ethyl ketone and heated to 50.degree. Then 113.16 g of cyclohexanone oxime are added in portions with stirring. The reaction mixture is stirred at 50 ° C. until no more isocyanate band can be seen in the IR spectrum. Then 17.70 g of Rhodafac PA 17 (emulsifying aid, Rhodia) and 1.67 g of neutralization by means of N, N-dimethylethanolamine are added and a homogeneous mixture of the components is prepared by stirring. A water-in-oil emulsion is produced from this solution by intensive mixing with 350.10 g of water using a dissolver, which is then phase-reversed into an oil-in by passage through a jet disperser at elevated pressure (4 bar) according to EP 0101007 - experiences water emulsion. The methyl ethyl ketone is distilled off in vacuo. The dispersion is then filtered through a filter with a mesh size of 10 µm. The result is a product with the following characteristics:
Flow time (ISO 4 cup, 23 ° C): 14 s
Solids content: 49.6% by weight
average particle size: 0.36 µm (laser correlation spectroscopy)
blocked NCO content: 14.25% (calculated, based on the solid)

Example 3 Manufacture of base pastes

The production of base pastes, as is usually described in US Pat Find practical application.

• 1. 3.1. Base paste based on a self-crosslinking polyurethane dispersion (®Bayhydrol VP LS 2153, Bayer AG), consisting of one in water dispersed polyhydroxyl compound and one dispersed in water blocked polyisocyanate (not according to the invention)

For a 30 minute grind in a bead mill, the following are Components weighed in and predispersed for about 10 minutes using a dissolver: 667.7 parts by weight of the 40% self-crosslinking polyurethane dispersion Bayhydrol VP LS 2153; 4.8 parts by weight of a commercially available anti-cratering agent; 4.8 parts by weight of a commercially available wetting agent; 4.1 parts by weight of one in the Anti-settling agent commonly used in the paint industry; 10.8 parts by weight of an aqueous Systems of conventional defoamers, 118.8 parts by weight of titanium dioxide; 1.3 parts by weight  Iron oxide black; 119.7 parts by weight of micronized heavy spar; 29.2 parts by weight carbonate-free talc and 38.8 parts by weight of distilled water. This results in a paste with a solids content of approx. 53.6% by weight.

• 1. 3.2. Base paste based on the dispersion I.2) essential to the invention Combination with an aqueous polyhydroxyl component II) (Bayhydrol® VP LS 2056, Bayer AG) (according to the invention)

The following components are weighed out, about 10 minutes using a dissolver predispersed and then stirred in a chilled pearl mill for 30 minutes grated: 387.9 parts by weight of the 47% dispersion of the polyhydroxyl compound Bayhydrol VP LS 2056; 237.8 parts by weight of the 60% dispersion I.2); 5.9% by weight Parts of a commercially available anti-cratering agent; 5.9 parts by weight of a commercially available Wetting agent; 4.9 parts by weight of an anti commonly used in the coatings industry sedatives; 13.0 parts by weight of a defoamer customary for aqueous systems; 143.6 parts by weight of titanium dioxide; 1.6 parts by weight of iron oxide black; 144.7 parts by weight micronized heavy spar; 35.3 parts by weight of carbonate-free talc and 19.4 parts by weight of distilled water. This results in a paste with a solid body content of approx. 65.0% by weight.

• 1.3. Base paste based on the dispersion I.3) essential to the invention Combination with an aqueous polyhydroxyl component II) (Bayhydrol® VP LS 2056, Bayer AG) (according to the invention)

The following components are weighed out, about 10 minutes using a dissolver predispersed and then stirred in a chilled pearl mill for 30 minutes grated: 339.9 parts by weight of the 47% dispersion of the polyhydroxyl compound Bayhydrol VP LS 2056; 315.3 parts by weight of the 49.6% dispersion I.3); 5.7 parts by weight of a commercially available anti-cratering agent; 5.7 parts by weight of one commercial wetting agent; 4.8 parts by weight of a ge in the paint industry common anti-settling agent; 12.6 parts by weight of a conventional for aqueous systems  Defoamer, 139.6 parts by weight of titanium dioxide; 1.5 parts by weight of iron oxide black; 140.6 parts by weight of micronized heavy spar and 34.3 parts by weight of carbonate-free Talc. This results in a paste with a solids content of approx. 63.2% by weight.

Example 4 Manufacture of aqueous fillers based on the base pastes 3.1. to 3.3.

The pastes are made according to the ratios given in the table below homogeneously mixed by dispersing for 10 minutes using a dissolver and if necessary with water to a processing viscosity of ≦ 35 s (ISO Cup 5 mm, ISO 2431). The compositions and characteristics of the obtained aqueous fillers are shown in Table 1 below.

Table 1

The solid contents of the fillers 2 to 5 according to the invention are significantly higher and their Viscosity stability after 40 ° C storage better than that of the high-quality Ver equal filler 1.

The aqueous fillers 1 to 5 were with a commercially available gravity cup gun with 5 bar air pressure at approx. 65% rel. Moisture (23 ° C) with a cathodic deposited electrodeposition primer (approx. 20 µm) coated zinc phosphated Spray-applied steel sheets.

The fillers hardened after 10 minutes flashing at 23 ° C in a forced air oven first 10 minutes at 70 ° C and then 20 minutes at 165 ° C. The dry film thickness was approx. 35 µm.

The properties of the fillers are listed in Table 2 below

Table 2

The fillers 2 to 5 according to the invention have compared to the commercially available Filler 1 has a very high hardness and a very good elasticity for this hardness. The Gloss values of the fillers 2 to 5 according to the invention are on a similar level as the gloss value of the standard filler 1.  

A commercially available automotive topcoat was applied to the filler layers Alkyd / melamine resin using an air atomizing spray gun with a Dry film thickness of approx. 30 µm applied and cured for 30 min at 130 ° C.

The most important test results that are decisive for the filler application are in the following table summarized. Resistance values not specified, such as e.g. B. solvent, water and salt spray resistance, fully correspond to the Practical requirements.

Test methods used

Topcoat level: Measurement of the ripple using a wave scan measuring device from Byk
Stone chip resistance: were used as test equipment

• a) Stone chip testing device according to VDA (Erichsen, model 508) with 2 times each 500 g steel shot (angular, 4-5 mm) bombarded with an air pressure of 1.5 bar at 23 ° C. Sampling was carried out with regard to hit the sheet (0 to 10, 0 = no punctures, 10 = very many Carbon copies).
• b) Single impact tester ESP-10 according to BMW standard DBP No. 34.31.390 (Fa. Byk), the flaking of the filler from the sheet is measured in mm.

Top coat level, measurement using wave scan (Byk), (corrected values given)

The lower the numerical values for both short and long ripple the better the topcoat is. The fillers 2 to 5 according to the invention therefore lead to a better topcoat level than the comparative filler 1.

Stone chip test

The fillers 4 to 5 according to the invention are at the same high level as that high-quality comparative filler 1, although the filler according to the invention a clear have higher hardness. This result is surprising and unpredictable. The fillers 2 and 3 according to the invention have a slightly poorer stone impact resistance.

Summary and discussion of the results

The fillers 2 to 5 according to the invention are distinguished by a very high Solids content and a very high hardness. Therefore, there were only a few Elasticity combined with poor stone chip resistance as well as poor topcoat level to be expected. However, the test results clearly show that the filler according to the invention contrary to the prior art both good elasticity values and very good stone chip resistance and Have topcoat stands and thus a high quality, commercially available Polyurethane fillers are superior. You have an unprecedented quality level with regard to the entire property spectrum.

Claims (10)

1. Binder mixture for aqueous stoving enamels

• A) special blocked polyisocyanates dispersed in water,
• B) polyhydroxyl compounds which are soluble or dispersible in water,
• C) if appropriate, resin water-soluble or dispersible crosslinkers and
• D) optionally further water-soluble or dispersible substances,

characterized in that component I)

• A) 40 to 80% by weight of one or more polyisocyanate components,
• B) 10 to 40% by weight of one or more blocking agents for isocyanate groups which are monofunctional in the sense of the isocyanate addition reaction,
• C) 1 to 30% by weight of one or more hydrophilizing agents,
• D) optionally further crosslinking substances and
• E) there are any customary additives,

with the proviso that component I) was produced either by a direct dispersing process or by the phase reversal process using a dispersing device with a high volume-based dispersing power and has an average particle size of the dispersion particles of 0.05 to 10 μm particle diameter. 2. Binder mixture according to claim 1, characterized in that as Polyisocyanate components A) of component I) aliphatic and / or cycloaliphatic biuret, isocyanurate, urethane, uretdione, allophanate and / or polyisocyanates containing iminooxadiazinedione groups become. 3. Binder mixture according to claim 1, characterized in that as Blocking agent B) of component I) oximes and / or pyrazoles be used. 4. Binder mixture according to claim 1, characterized in that as Hydrophilizing agent C) of component I) external emulsifiers be set. 5. Binder mixture according to claim 1, characterized in that as Component II) polyhydroxy polyester, polyhydroxy polyether, polyhydroxy polyurethane, polyhydroxycarbonates, urethane-modified polyester polyols, urethane modified polyether polyols, urethane modified polycarbonate polyols, hydroxyl-containing polymers, polyester poly acrylate polyols, polyether polyacrylate polyols, polyurethane polyacrylate polyols, Polyester polyurethanes, polyether polyurethanes, polycarbonate polyrethanes, Polyether polyesters or mixtures thereof are used. 6. Binder mixture according to claim 1, characterized in that as Component III) water-soluble or dispersible blocked poly Isocyanates are used.   7. Binder mixture according to claim 1, characterized in that as Component III) water-soluble or dispersible amino resins be used. 8. Use of the binder mixtures according to claim 1 to 7 for Production of, if necessary, the usual auxiliaries and additives Aqueous stoving lacquers containing coating technology. 9. Use of the aqueous stoving lacquer according to claim 8 for Her provision of fillers for metal parts. 10. Use of the aqueous stoving lacquer according to claim 8 for Her Provision of fillers for automotive body parts.