Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1999-12-22
2002-03-05
Green, Anthony (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S447000, C106S456000, C106S459000, C106S460000, C106S493000, C106S499000, C106S504000
Reexamination Certificate
active
06352586
ABSTRACT:
The invention relates to water-dilutable coating compositions comprising binders, aluminum pigment, and an aqueous diluent.
Water-thinnable coating compositions comprising binders, aluminum pigment and an aqueous diluent are known and are intended for use in particular in the finishing of automobiles, for producing metallic coating systems.
Metallic coating systems are nowadays applied preferably by the so-called basecoat/clearcoat technique, in which a basecoat pigmented with aluminum pigments is applied first and then coated over with a clearcoat.
A particular problem of aqueous coating compositions for producing metallic coating systems is that they often have a pH which is so high that the aluminum pigments used react with water, forming hydrogen. This phenomenon results in a range of problems, especially when the coating materials are stored in closed containers.
A range of processes have been disclosed by means of which aluminum pigments are to be passivated in such a way (cf. e.g. EP-A-0581235) that no hydrogen at all, or only a very small amount, is evolved. All of these processes, however, have the disadvantage that the gassing stability is still not satisfactory. With the use of known aluminum pigments passivated by chromation, it is necessary to accept impairments in the shade and metallic effect (flop) of the metallic coating systems.
The object on which the present invention is based is to provide a water-dilutable coating composition comprising binders, inorganic and, if desired, organic pigments and also further customary additives such as solvents, fillers, plasticizers, stabilizers, wetting agents, dispersing auxiliaries, levelling agents, defoamers, catalysts and further additives, individually or in a mixture with one another, which do not have the aforementioned disadvantages of the prior art.
This object is achieved in accordance with the invention by said coating composition comprising at least one phosphoric ester and at least one fatty alcohol alkoxylate.
The water-dilutable coating compositions of the invention can in principle comprise all binders suitable for water-dilutable coating compositions.
Binders which can be used include, accordingly, both refined natural products, examples being products of rosin and oils or cellulose nitrates, and resins whose composition is entirely synthetic. The latter includes phenolic resins, amine resins (e.g., urea resins, melamine resins), alkyd resins, polyvinyl acetates, epoxy resins, polyurethane resins, polyester resins, rosin-modified phenolic resins, chlorinated rubbers, chlorinated polypropylene, cyclorubbers, ketone resins, and acrylate resins.
Binders used in particular are water-dilutable or water-dispersible polyurethane resins, polyacrylate resins, polyester resins and amino resins, which can be prepared in organic solution, and also mixtures thereof.
The polyurethane resins which can be used as binders are known in principle. Suitable examples are the polyurethane resins described in the literature for use in water-based coating materials, provided these polyurethane resins—in a modification of the preparation described in the respective literature—can be prepared in the form of organic solutions.
Examples of suitable polyurethane resins are the resins described in the following documents: EP-A-355433, DE-A 3545618, DE-A 3813866, and the as yet unpublished German Patent Application DE 4005961.8. For further details of the preparation of the polyurethane resins and examples of suitable compounds, therefore, reference may be made to these documents.
The polyacrylate resins used as binders are likewise known and are described, for example, in DE-A 3832826. Suitable resins are general water-thinnable or water-dispersible polyacrylate resins which can be prepared in the form of organic solutions.
Also suitable as binders are water-dilutable or water-dispersible polyester resins which can be prepared in the form of organic solutions. Use is made, for example, of corresponding commercially customary water-dilutable or water-dispersible polyester resins, and also the polyester resins commonly used in water-based coating materials.
Further suitable binders include water-dilutable or water-dispersible amino resins. Preference is given to the use of water-dilutable melamine resins. These are, generally, etherified melamine formaldehyde condensates.
Apart from the degree of condensation, which should be as low as possible, the water-solubility of the amino resins depends on the etherifying component, with only the lowest members of the alcohol or ethylene glycol monoether series giving water-soluble condensates. The greatest importance is possessed by the methanol-etherified melamine resins. With the use of solubilizers, butanol-etherified melamine resins can also be dispersed in an aqueous phase. A further possibility is to insert carboxyl groups into the condensate. Transetherification products of highly etherified formaldehyde condensates with oxycarboxylic acids are soluble in water following neutralization, by way of their carboxyl groups, and may be present in the base paints.
As binders it is of course also possible to use mixtures of the aforementioned binders and, in addition or alone, other water-dilutable or water-dispersible binders.
The coating compositions of the invention can comprise customary additives such as solvents, plasticizers, stabilizers, wetting agents, rheological auxiliaries, dispersing auxiliaries, levelling agents, defoamers and catalysts, and also additives individually or in a mixture in the customary amounts. These substances can be added to the individual components and/or to the mixture as a whole.
The coating compositions of the invention can comprise, besides water, the customary solvents, examples being aliphatic or aromatic hydrocarbons, mono- or polyhydric alcohols, ethers, ethers, glycol ethers and esters thereof, and ketones, such as for example, toluene, xylene, butanol, ethyl glycol or butyl glycol (=ethylene glycol monoethyl or monobutyl ether) and acetates thereof, butyldiglycol (ethylene glycol dibutyl ether), ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, acetone, isophorone, or mixtures thereof.
Further components which may be added to the basecoats of the invention include crosslinked polymeric microparticles, as are disclosed, for example in EP-A-38 127, and/or customary organic or inorganic additives. For instance, examples of effective thickeners are sheet silicates, water-soluble cellulose ethers, such as hydroxyethyl cellulose, methyl cellulose or carboxymethyl cellulose, and also synthetic polymers having ionic and/or associative groups, such as polyvinyl alcohol, poly(meth)acrylic acid, polyvinyl pyrrolidone, styrene maleic anhydride or ethylene maleic anhydride copolymers and their derivatives, or else hydrophobically modified ethoxylated piperidine and triethanolamine. Particular preference is given to the use of tertiary amines as neutralizing agents, especially dimethylethanolamine, triethylamine, tripropylamine and tributylamine.
The basecoat compositions of the invention can comprise all of the dyes or pigments which are known and are customary in the coatings industry.
Examples of dyes and pigments, which can be organic or inorganic in nature, are titanium dioxide, graphite, carbon black, zinc chromate, strontium chromate, barium chromate, lead chromate, lead cyanamide, lead silicochromate, zinc oxide, cadmium sulfide, chromium oxide, zinc sulfide, nickel titanium yellow, chromium titanium yellow, iron oxide red, iron oxide black, ultramarine blue, phthalocyanine complexes, naphthol red, quinacridones, halogenated thioindigo pigments or the like.
Particularly preferred pigments are metal powders, individually or in a mixture, such as copper, copper alloys, aluminum and steel, preferably aluminum powders, which are used in at least predominant proportion and, specifically, in an amount of from 0.5 to 25% by weight based on the overall solids content of the binders in the coating composition
BASF Coatings AG
Green Anthony
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