DE3321180A1 - Process for the preparation of aqueous dispersions and the use of these for the preparation of metal effect finishes - Google Patents

Abstract

A process in which binders, pigments, aluminium bronze and optionally further assistants are combined to give a mixture containing a maximum of 30% of organic solvent, and this mixture is converted into an aqueous dispersion in the presence of an emulsifier, gives paints (surface coatings, lacquers) which are highly suitable as the base coat of two-coat metal-effect finishes.

Description

Patents, trademarks and licenses Pv / by-c

June 10, 1983

Process for the production of aqueous dispersions and their use for the production of metal effect coatings

The invention relates to a method of manufacture aqueous dispersions based on a water-insoluble polyester, alkyd resin or polyacrylate resin, Aluminum bronze and optionally a cellulose ester and the use of these dispersions for Production of metal effect paints.

Metal effect paints are very popular, especially among buyers of motor vehicles. The two-layer wet-on-wet painting process is primarily used for coating, whereby initially a pigmented, aluminum bronze containing basecoat is sprayed on, which after a short flash off is sprayed over with a clear lacquer without intermediate baking. Both layers are subsequently branded together. This two-layer painting process combines production security with

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high technical quality of the paintwork obtained. In terms of environmental protection and raw material costs, it is desirable to use the paints in the form of aqueous dispersions.

5 main problem of the metallic effect two-layer painting The use of aqueous dispersions is the fact that there is a poor binder at the interface between the two layers Zone forms, which leads to a reduced adhesion of the clearcoat to the basecoat.

It should also be noted that for the solution of the invention Problem, only those measures seem suitable that do not involve excessive shear energy get by, as otherwise the flaky aluminum bronze will be partially destroyed and the achievable metal effect would suffer.

European patent application 38 127 discloses aqueous basecoat materials for two-coat metal effect coatings based on a partially cross-linked polymeric microgel known, the pseudoplastic or has a thixotropic character. The European patent application 69 9 36 relates to a method for Production of aqueous dispersions, which are used as basecoats for two-coat metal effect finishes can be, wherein unsaturated compounds are polymerized in the presence of cellulose ester. However, both registrations cannot solve the above task.

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Surprisingly, a method leads to the goal, after which binder, pigment, aluminum bronze and
optionally further auxiliaries for a mixture
combined, which contains a maximum of 30 wt .-% organic solvent, and the resulting mixture in the presence of a. Emulsifier processed into an aqueous dispersion. In this way, a directly applicable aqueous metallic effect basecoat for two-coat painting is obtained. Basecoats produced therefrom show excellent intercoat adhesion to the clearcoat and a metallic effect which is retained without disruption when the clearcoat is applied wet-on-wet.

The invention is therefore a method for
Production of an aqueous metal effect basecoat
the end

A) 10-30 parts by weight of oil-free polyester, alkyd resin and / or polyacrylate resin with an acid number of at most 15, preferably no more than 8,

B) 2.5-15 parts by weight of water-soluble aminoplast resin, C) 2-10 parts by weight of aluminum bronze,

D) 0.1-5 parts by weight of emulsifier,

E) 0-10 parts by weight of cellulose ester,

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F) organic solvent and optionally

G) other aids,
characterized in that one

I. First the components A-C, optionally D,

possibly E and so much F and possibly

G mixes with one another so that this mixture contains less than 30% by weight of F and less than 20% by weight of water, and

II. Then this mixture, if appropriate with D

10 (if not already added in step I) and with enough water that the components AG
Add to 100 parts by weight together with the water, processed into a dispersion.

Another object of the invention is the use of dispersions produced in this way for the production of metallic effect two-layer coatings.

Preferred oil-free polyesters and alkyd resins A) are those which are known by polycondensation Can produce processes from alcohols and carboxylic acids, as for example in Römpp's Chemielexikon, Vol. 1, P. 202, Frankh'sche Verlagsbuchhandlung, Stuttgart, 1966 or defined by D.H. Solomon, The Chemistry of Organic Filmformers, pp. 75-101, John Wiley & Sons Inc., New York, 1967 and in H. Wagner and H.F. Sarx, Lacquer synthetic resins, Carl Hanser Verlag, Munich 1971, pp. 96-113, are described.

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"Alkyd resins" in this application are fatty acid and oil-modified polyesters understood.

Acid components preferred for the synthesis of the polyesters or alkyd resins A are aliphatic and cycloaliphatic saturated or unsaturated and / or aromatic polybasic carboxylic acids, preferably Di-, tri- and tetracarboxylic acids, with 2 to 14, preferably 4 to 12 carbon atoms per molecule or their esterifiable derivatives (e.g. anhydrides or Esters), e.g. phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydro- and hexahydrophthalic anhydride, Endomethylenetetrahydrophthalic acid, Succinic acid, glutaric acid, sebacic acid, azelaic acid, trimellitic acid and trimellitic anhydride, Pyromellitic anhydride, fumaric acid and maleic acid. Phthalic anhydride is the most common acid component. The polyesters or alkyd resins A should not be more than 20 mol%, based on the condensed Polycarboxylic acid residues, fumaric and maleic

Contains 20 acid residues.

Alcohols preferred for the synthesis of the polyesters or alkyd resins A are aliphatic and cycloaliphatic and / or araliphatic alcohols with 1-15, preferably 2-6 carbon atoms, and 1-6, preferably 1-4, OH groups bound to non-aromatic carbon atoms per molecule, e.g. glycols such as ethylene glycol, 1,2-propanediol and -1,3, butanediol-1,2, -1,3, and -1,4, 2-ethyl-

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1,3-propanediol, 2-ethylhexanediol-1,3, neopentyl glycol, 2,2-trimethylpentanediol-i, 3, hexanediol-1,6, cyclohexanediol-1,2 and -1,4, 1,2- and 1, 4-bis (hydroxymethyl) cyclohexane, adipic acid bis (ethylene glycol ester); Ether alcohols such as di- and triethylene glycol, dipropylene glycol; oxalkylated bisphenols with two C ₂ -C, -oxalkyl groups per molecule, perhydrogenated bisphenols; Butanetriol-1,2,4, hexanetriol-1,2,6, trimethylolethane, trimethylolpropane, trimethylolhexane, glycerin, pentaerythritol, dipentaerythritol, mannitol and sorbitol; Chain-terminating monohydric alcohols with 1 to 8 carbon atoms such as propanol, butanol, cyclohexanol and benzyl alcohol. The most common alcohols are glycerine, trimethylolpropane, neopentyl glycol and pentaerythritol.

Monocarboxylic acids preferred for the production of the polyesters or alkyd resins A are aliphatic and cycloaliphatic saturated and unsaturated and / or aromatic monocarboxylic acids with 3-24 carbon atoms per Molecule such as benzoic acid, p-tert-buty! Benzoic acid, toluic acid, hexahydrobenzoic acid, abietic acid and Lactic acid.

The alkyd resins or polyester A can also be monohydric alcohols such as methanol, propanol, cyclohexanol, 2-ethylhexanol, benzyl alcohol in amounts up to 15.

% By weight, based on alkyd resins or polyester A, condensed in. It is also possible to add up to Replace 25% of the ester bonds with urethane bonds.

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The alkyd resins or polyesters falling within the scope of the invention are water-insoluble, meltable Masses which cannot be distributed in the aqueous phase without further additives. It is not because of that desired, polyalkylene oxides, so-called polywaxes, as polyhydric alcohols for the synthesis of component A. to use because such ingredients make the resin hydrophilic, resulting in poor water resistance of the hardened product.

In the alkyd resins A, the slope is calculated as triglyceride and based on the alkyd resin, generally 5 to 50, preferably 20 to 40% by weight. the drying or non-drying fatty acids which generally contain 6 to 24 carbon atoms can either used as such or in the form of their glycerol esters (triglycerides).

Vegetable and animal oils, fats or fatty acids are preferred, such as coconut, Peanut, castor, wood, olive, soybean, linseed, cottonseed oil, safflower oil or fatty acids, dehydrated castor oil or fatty acid, monounsaturated fatty acids, lard, tallow and trane, Tall oil fatty acids and synthetic fatty acids that are naturally derived from conjugation or isomerization unsaturated oils or fatty acids can be produced. Preferred saturated fatty acids are e.g. Coconut oil fatty acids, cC-ethylhexanoic acid, isononanoic acid (3,4,4-trimethylhexanoic acid) as well as palmitic and

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Stearic acid and synthetic saturated branched fatty acids.

The number average molecular weight of the polyester or alkyd resin A is 2000-10,000 (up to molecular weights of 5000 vapor pressure osmometric determined in dioxane and acetone, with differing values the lower value than is viewed correctly; at molecular weights above 5000 determined by membrane osmometry in acetone).

Preferred polyacrylate resins A are obtained by copolymerizing vinyl or vinylidene monomers, e.g. Styrene, cC -methylstyrene, o- or p-chlorostyrene, o-, m- or p-methylstyrene, p-tert.-butylstyrene, (meth-) Acrylic acid, (meth) acrylonitrile, acrylic and methacrylic acid alkyl esters with 1 to 8 carbon atoms in the alcohol component, for example ethyl acrylate, methyl acrylate, n- or iso-propyl acrylate, n-butyl acrylate, "^ .- ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, tert-butyl acrylate, methyl methacrylate, Ethyl methacrylate, n- or iso-propyl methacrylate, butyl methacrylate, Isooctyl methacrylate and optionally mixtures thereof; Hydroxyalkyl (meth) acrylates with 2-4 carbon atoms in the alkyl group, e.g. 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; Trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, diesters of Fumaric acid, itaconic acid, maleic acid with 4-8 carbon atoms in the alcohol component; Acrylonitrile,

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(Meth) acrylic acid amide, vinyl esters of alkane monocarboxylic acids with 2-5 carbon atoms such as vinyl acetate or vinyl propionate or mixtures of the monomers mentioned, N-methoxymethyl (meth) acrylic acid amide.

Preferred monomers are styrene and (meth) acrylic acid alkyl esters with 1-8 carbon atoms in the alcohol component and their mixtures.

The polyacrylate resins A have average molecular weights M from 1000-20,000, the molecular weights as described above for the polyesters or alkyd resins A, determined can be.

The monomers are used in essentially the same proportions as they are used for the polymerization are built into the copolymer A, the polymerized units being essentially random are distributed.

Water-soluble amino resins B for the purposes of the invention are optionally modified and plasticized Urea resins, melamine resins and guanamine and sulfonamide resins. It is in each case to Condensation products of formaldehyde with urea, melamine, guanamine and sulfonamide, which are commonly found in alkaline medium.

Preferred emulsifiers D are in Ulimann's Encyclopedia of technical chemistry, 4th edition, volume 10,

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449-473, Verlag Chemie, Weinheim 1975, and in Mc Cutcheon's "Detergents & Emulsifiers", Mc Cutcheon Division, Mc Publishing Co., Glen Rock, N.J. (1979) described.

Particularly preferred emulsifiers D are anion-active emulsifiers which are derived from non-ionic surfactants; so preferably carboxylates, sulfonates, sulfates, phosphates, phosphites and phosphonates, which are produced from surface-active alkyl, aryl, acyl, alkaryl polyglycol ethers, acylated or alkylated alkanolamine polyglycol ethers, whereby the term "polyglycol ethers" includes in particular polyethylene glycols, polypropylene glycols and poly (ethylene / propylene) glycols with average molecular weights M _n of 500 to 3000

be understood.

The surface-active non-ionic surfactants can be prepared using methods known from the literature (Dr. K. Lindner, Surfactants, textile auxiliaries, detergent raw materials, scientific Verlagsgesellschaft, Stuttgart 1964), e.g.

by reaction with> ^Λ <-halogenocarboxylic acids to carboxylates, with sulfuric acid or chlorosulphonic acid to form sulphates, with phosphorus oxides, phosphorus halides or phosphoric acid to form phosphites or phosphates, by reaction with epichlorohydrin and subsequent reaction with sodium hydrogen sulphite, by reaction with sulfones, by reaction with isethionic acid or chloroethanesulphonic acid or by reaction with maleic acid an-

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hydride and subsequent sodium bisulfite addition to sulfonates or by reaction with phosphonocarboxylic acids to phosphonates.

Preferred non-ionic materials which are suitable as starting materials for the preparation of the anion-active emulsifiers D Surfactants are alkyl, acyl, aryl, alkylaryl polyglycol ethers, which have 10-20 carbon atoms in the alkyl, acyl, aryl or alkylaryl radical and by alkoxylation of in the alkanols, carboxylic acids, phenols or alkylphenols with ethylene oxide and / or common in surfactant chemistry Propylene oxide is formed. These ethylene oxide / propylene oxide Mi see them can be in surfactant chemistry Trade common block, mixed or mixed block adducts.

Particularly preferred anion-active emulsifiers D are based on phosphates, sulfates and, in particular, sulfonates of sulfosuccinic acid, which is different from C-p-C-Q-alkyl or derive octyl or nonylphenyl polyethoxylates which have an average of more than 10 ethylene oxide units and preferably more than 20 ethylene oxide units per molecule have, as well as their mixtures.

Preferred cellulose esters E are the reaction products of cellulose with acetic anhydride and butyric acid or propionic anhydride, free OH groups still being retained. In particular, they are Cellulose mixed esters of acetic acid and butyric acid suitable (Ulimann, Encyclopadie der Technischen Chemie, Verlag Chemie, Weinheim, Vol. 9, p. 227).

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Preferred organic solvents F are those solvents which are dissolved in water at room temperature The ratios that are passed through when preparing the dispersion, not miscible in a single phase are, in particular acetic acid and propionic acid

Cj-Ccj-alkyl esters, such as methyl, ethyl, propyl, isopropyl, η-butyl, iso-butyl, sec-butyl, amyl, methoxypropyl, 3-methoxybutyl acetate or propionate. An overview of the finds common solvents for this application

in "Varnishes and Solvents", Verlag Chemie, Weinheim 1979, p. 158 ff.

Further auxiliaries G are, for example, water, leveling aids, Thixotropic agents, wax-like substances such as ethylene copolymers, wetting agents, thickeners, 15 Preservatives and Pigments.

The dispersing can in principle be carried out so that from components A, B, C, E, F and G one Paste which is then introduced into the aqueous phase containing the emulsifier D. Usually however, one will prefer to mix the water into a mixture consisting of components A-F and optionally G stir in.

According to a particularly preferred embodiment, an oil-free polyester with a OH number from 35 to 70, 50-80% in an organic Solvent dissolved and with a cellulose ester, preferably cellulose acetobutyrate, about 15-30 wt .-% in

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dissolved in an organic solvent, combined. Furthermore, an aminoplast resin, approx. 60% by weight in Water, as well as the emulsifier, the auxiliaries and the aluminum bronze and the coloring pigment were added. After further homogenization, water is slowly added dropwise. In doing so, the initially present one runs through Water-in-oil emulsion the so-called inversion point and forms an oil-in-water emulsion.

The production method using the paste and subsequent dispersion ensures that the aluminum bronze is homogeneously distributed in the individual particles of the disperse phase.

The two-layer metal-effect paint can at temperatures of 80 to 180 ⁰ C, are baked preferably 110 to 14O ⁰ C.

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Examples

The parts mentioned in the following examples are parts by weight, percentages relate to Weight.

example 1

20.96 parts of an oil-free polyester made from 27.23 parts of terephthalic acid, 24 parts of isophthalic acid, 41 parts of neopentyl glycol, 8.7 parts of trimethylolpropane and- 13 parts of adipic acid with an OH number of 57 and an acid number of 4.80% in 3-Methoxybutyl acetate was dissolved in a laboratory dissolver with an edge speed of the dissolver disk of 3 m / sec with 2 parts of an emulsifier (Sodium salt of the phosphoric acid ester of nonylphenol,

15 reacted with 20 mol of ethylene oxide) homogenized. Then 2.1 parts of cellulose acetobutyrate, dissolved in 8.4 parts of butyl acetate, and 9 parts of a water-soluble urea / formaldehyde resin, in ^ 9 parts of water dissolved, and 0.37 parts of a thickener

by means of dissolved in 1.3 parts of water, added. After this mixture has been stirred into a homogeneous paste 6 parts of aluminum bronze were added to it in portions and then slowly processed with 35.8 parts of water until an aqueous dispersion varnish with a solids content of 40.43%, a content of 13.6% solvent and a vis-

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viscosity corresponding to an expiry time of 58 seconds (DIN 53 211, DIN 4 cup) was available.

Comparative example 1

43.5 parts of a 48.3% strength aqueous dispersion consisting of 72.1% of the oil-free polyester were obtained Example 1 and 24% cellulose acetobutyrate and 3.9% of an emulsifier (sodium salt of sulfonosuccinic acid, esterified with ethoxylated nonylphenol with 30 mol of ethylene oxide) slowly with 8 parts of aluminum bronze and 11 parts of a 50% strength aqueous urea / formaldehyde resin are added. Then 15 Parts of a solvent mixture consisting of equal parts of ethyl glycol, ethyl glycol acetate, methyl glycol, Methyl glycol acetate and diacetone alcohol, and 2 parts of the sodium salt of the phosphoric acid ester one with 20 mol Ethylene oxide converted nonylphenol was added in a laboratory dissolver. Then 31.5 parts of water were added added. The result was an aqueous emulsion paint with a solids content of 28%, a solvent content of 15% and a viscosity corresponding to a flow time of 12 seconds (DIN 53 211, DIN 4 cup).

use

The aqueous basecoat materials from Example 1 and Comparative Example 1 were applied using a cataphoresis Primer and subsequent filler coated sheet steel with a spray gun at a distance of 30-40 cm, with a nozzle bore of 1.4 mm and one

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Injection pressure of 4.0 bar applied in a cross pass. Then three minutes was flashed with heated to 6O ⁰ C air. The dry film thicknesses achieved were
10-15 μm. Then it was applied to the respective basecoat

a commercial polyacrylate paint made from 75 parts of a by polymerizing 21 parts of styrene, 28 parts of butyl acrylate, 21 parts of methyl methacrylate, 29 parts Hydroxypropyl acrylate and 2 parts of acrylic acid prepared Polyacrylate with a middle. Molecular weight Mn of 2000, an OH number of 135 and one Acid number of 20, dissolved in xylene / butyl acetate (1: 1 Parts by weight) and 25 parts of a commercially available, water-insoluble partially isobutanol-etherified one Melamine resin applied and baked at 130 ° C / 30 min.

Example 2

The production of an aqueous basecoat was analogous to Example 1 with the use of color pigments repeated:

20 Composition: 21 parts of oil-free polyester, dissolved in 9 parts of butyl acetate,
5 parts of butyl acetate,
2 parts of emulsifier as in Example 1,
5.6 parts of urea resin, dissolved in 5.6 parts of water,

• 0.1 part pigment dispenser, dissolved in 0.4 part water,

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- yf-

Z ι i possibly

0.375 parts thickener, in 1.125 parts

Dissolved water,

0.2 parts preservative, 2 parts aluminum bronze and 5.5 parts pigment.

The paint components listed were, as described in Example 1, a viscous, easily stirrable one Processed paste and then converted into an aqueous dispersion with the addition of 42.6 parts of water. The result was a dispersion with a solids content of 36.2% and a solvent content of 14.0% and a viscosity corresponding to an outflow time of 22 seconds (DIN 53 211, DIN cup 4). Afterward it was processed into a 2-layer metal effect paint as described above.

Example 3

The preparation of an aqueous basecoat material according to Example 1 was repeated with the difference that none Cellulose acetobutyrate was also used.

Made from 21.04 parts of oil-free polyester, in 5.26 parts

Butyl acetate dissolved,

2.0 parts of emulsifier as in Example 1, 5.6 parts of urea resin in 5.6 parts of water

solved,

0.375 parts of thickener in 1.125 parts of water, 6 parts of aluminum bronze and 8.5 parts of 3-methoxybutyl acetate

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a viscous, easily stirrable paste was produced and with 44.5 parts of water in an aqueous dispersion with a solids content of 35.1%, a content of 13.8% organic solvent and a viscosity corresponding to an outflow time of 24 seconds (DIN 53 211, DIN 4 cup).

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Example 1 Comparison 1 Example 2 Example 3

Gardner gloss) under load (20 ° angle) [after 1000 h weatherometer according to DIN 67 530) after 2000 h weather sounder

Crack formation after 2000 h weatherometer

88 87 88 89 86 87 87 87 83 81 83 84

if.

if.

if.

if.

Adhesion (cross-cut) without load test according to DIN 53 151) after 1000 h weatherometer

after 2000 h weatherometer

The cross-cut test provides a measure of the interlayer adhesion.

0-1 4th 0 0 0-1 4th 0-1 0-1 0-1 4th 0-1 0-1

Claims (2)

»· Ti • ft 4 Claims Process for the production of an aqueous metal effect basecoat the end A) 10-30 parts by weight of oil-free polyester, alkyd resin and / or polyacrylate resin of acid number no more than 15, B) 2.5-15 parts by weight of water-soluble aminoplast resin, C) 2-10 parts by weight of aluminum bronze, 10 D) 0.1-5 parts by weight of emulsifier, E) 0-10 parts by weight of cellulose ester, F) organic solvent and optionally G) further tools, characterized in that one I. first the components A-C, optionally D, optionally E and so much F and optionally G mixes with one another that this mixture contains less than 30% by weight of F and less than 20% by weight of water, and Le A 22 351 II. Then this mixture, optionally with D (if not already added in step I) and with enough water that the components AG are together with the water
Add 100 parts by weight, processed into a dispersion. 2. Use by the method according to claim 1 produced Dispersions for the production of metal effect two-layer coatings . Le A 22 351