Aqueous dispersion of a copolymer

Abstract

An aqueous dispersion containing at least one copolymer, the copolymer being preparable by initially charging an aqueous dispersion of at least one polyurethane, and then polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane, where a water-soluble initiator is used, the metered addition of the olefinically unsaturated monomers is effected in such a way that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers, in the reaction solution is not exceeded over the entire duration of the reaction, and the mixture of the olefinically unsaturated monomers contains at least one polyolefinically unsaturated monomer.

Claims

1. An aqueous dispersion, comprising at least one copolymer obtained by (i) initially charging an aqueous dispersion of at least one polyurethane, and then (ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane, wherein: the polymerizing occurs in the presence of a water-soluble initiator; a metered addition of the olefinically unsaturated monomers occurs such that a concentration of 6.0% by weight, based on a total amount of the olefinically unsaturated monomers, in a reaction solution of the polymerizing is not exceeded during the entire duration of the polymerizing; and the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer.

2. The aqueous dispersion as claimed in claim 1, wherein the metered addition of the olefinically unsaturated monomers occurs such that a concentration of 5.0% by weight, based on the total amount of the olefinically unsaturated monomers, in the reaction solution is not exceeded during the entire duration of the polymerizing.

3. The aqueous dispersion as claimed in claim 2, wherein the metered addition of the olefinically unsaturated monomers occurs such that a concentration of 4.0% by weight, based on the total amount of olefinically unsaturated monomers, in the reaction solution is not exceeded during the entire duration of the polymerizing.

4. The aqueous dispersion of claim 1, wherein the mixture of the olefinically unsaturated monomers comprises 0.1 to 6.0 mol % of the at least one polyolefinically unsaturated monomer.

5. The aqueous dispersion of claim 1, wherein the mixture of the olefinically unsaturated monomers comprises 0.1 to 2.0 mol % of the at least one polyolefinically unsaturated monomer.

6. The aqueous dispersion of claim 1, wherein the mixture of the olefinically unsaturated monomers comprises 0.1 to 6.0 mol % of allyl methacrylate and does not contain any further polyolefinically unsaturated monomers.

7. The aqueous dispersion of claim 1, wherein the mixture of the olefinically unsaturated monomers comprises 0.1 to 2.0 mol % of allyl methacrylate and does not contain any further polyolefinically unsaturated monomers.

8. The aqueous dispersion of claim 1, wherein the mixture of olefinically unsaturated monomers comprises less than 10.0% by weight of vinylaromatic monomers, based on the total amount of olefinically unsaturated monomers.

9. The aqueous dispersion of claim 1, wherein the mixture of olefinically unsaturated monomers comprises less than 5.0% by weight of vinylaromatic monomers, based on the total amount of olefinically unsaturated monomers.

10. The aqueous dispersion of claim 1, wherein the mixture of olefinically unsaturated monomers does not contain any vinylaromatic monomers.

11. The aqueous dispersion of claim 1, wherein the aqueous dispersion has a gel content of 40 to 90% by weight, based on solids in the dispersion.

12. The aqueous dispersion of claim 1, wherein the copolymer comprises (A) a core comprising at least one polyurethane, and (B) a shell comprising at least one polymer obtained by polymerization of olefinically unsaturated monomers.

13. A coating material, comprising the aqueous dispersion of claim 1.

14. A waterborne basecoat, comprising the aqueous dispersion of claim 1.

15. A process for producing a multicoat color and/or effect paint system, the process comprising (i) applying a pigmented waterborne basecoat to a substrate, (ii) forming a polymer film from the pigmented waterborne basecoat applied in stage (i), (iii) applying a clearcoat layer to the polymer film as a basecoat layer, and then (iv) curing the basecoat layer together with the clearcoat layer, wherein the pigmented waterborne basecoat comprises the aqueous dispersion of claim 1.

16. The process of claim 15, wherein the substrate is an automobile body, a plastic part for installation of an automobile body, or both.

17. A process for producing the aqueous dispersion of claim 1, the process comprising (i) initially charging an aqueous dispersion of at least one polyurethane, and then (ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane, wherein: the polymerizing occurs in the presence of a water-soluble initiator; a metered addition of the olefinically unsaturated monomers occurs such that a concentration of 6.0% by weight, based on a total amount of the olefinically unsaturated monomers, in a reaction solution of the polymerizing is not exceeded during the entire duration of the polymerizing; and the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer.

Description

EXAMPLES

(1) Unless stated otherwise, the hydroxyl number in the examples which follow was determined based on R.-P. Krüger, R. Gnauck and R. Algeier, Plaste and Kautschuk, 20, 274 (1982), by means of acetic anhydride in the presence of 4-dimethylaminopyridine as catalyst in a tetrahydrofuran (THF)/dimethylformamide (DMF) solution at room temperature, with full hydrolysis of the remaining excess of acetic anhydride after acetylation and potentiometric back-titration of the acetic acid with alcoholic potassium hydroxide solution. Acetylation times of 60 min were sufficient in all cases to guarantee a full conversion.

(2) Unless stated otherwise, the acid number in the examples which follow was determined based on DIN EN ISO 2114 in homogeneous solution from THF/water (9 parts by volume of THF and 1 part by volume of distilled water) with ethanolic potassium hydroxide solution.

(3) Unless stated otherwise, solids content, also referred to hereinafter as solids, was determined in the examples which follow to DIN EN ISO 3251 at 130°; 60 min, starting weight 1.0 g.

(4) The number-average molar mass (M.sub.n) in the examples which follow, unless stated otherwise, was determined by means of a 10.00 vapor pressure osometer (from Knauer) on concentration series in toluene at 50° C. according to E. Schröder, G. Müller, K.-F. Arndt, “Leitfaden der Polymercharakterisierung” [Guidelines for Polymer Characterization], Akademie-Verlag, Berlin, p. 47-54, 1982.

(5) Polyurethane Dispersions

Example D-P1

Preparation of a Dispersion of an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(6) A dispersion of an alpha-methylstyryl-containing polyurethane was produced based on the patent specification DE 19948004 B4, page 27, example 1, “Herstellung eines erfindungsgemäβen Polyurethans (B)” [Preparation of an inventive polyurethane (B)], except that the solids in the resulting dispersion were only 29% rather than 35% by weight. Based on the adduct (B2) mentioned in the patent specification DE 19948004 B4, preparation example 1, an adduct was prepared with monoethanolamine and trimethylolpropane rather than with diethanolamine:

(7) For this purpose, a reaction vessel equipped with stirrer, internal thermometer, reflux condenser and electrical heater was first charged under nitrogen with 200.0 parts by weight of methyl ethyl ketone, 800.0 parts by weight of N-methylpyrrolidone and 221.3 parts by weight of monoethanolamine (from BASF SE) at 20° C. Added dropwise to this mixture over the course of one and a half hours were 778.7 parts by weight of 1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (TMI® (META) Unsaturated Aliphatic Isocyanate, from Cytec) having an isocyanate content of 20.4% by weight of isocyanate, in such a way that the reaction temperature of 40° C. was not exceeded. The resulting reaction mixture was stirred until no free isocyanate groups were detectable any longer. Thereafter, the reaction mixture was stabilized with 200 ppm of hydroquinone.

(8) The theoretical solids content of the thus produced solution of the adduct described was 50% by weight.

(9) Then, in a further reaction vessel equipped with stirrer, internal thermometer, reflux condenser and electrical heater, 431.7 parts by weight of a linear polyester polyol and 69.7 parts by weight of dimethylolpropionic acid (from GEO Speciality Chemicals) were dissolved in 355.8 parts by weight of methyl ethyl ketone and 61.6 parts by weight of N-methylpyrrolidone under nitrogen. The linear polyester polyol had been prepared beforehand from dimerized fatty acid (Pripol® 1012, from Uniqema), isophthalic acid (from BP Chemicals) and hexane-1,6-diol (from BASF SE) (weight ratio of the starting materials: dimeric fatty acid to isophthalic acid to hexane-1,6-diol=54.00:30.02:15.98) and had a hydroxyl number of 73 mg KOH/g solids and a number-average molar mass of 1379 g/mol.

(10) To the resulting solution were added, at 45° C., 288.6 parts by weight of isophorone diisocyanate (Basonat® I, from BASF SE) having an isocyanate content of 37.75% by weight. After the exothermic reaction had abated, the reaction mixture was heated gradually to 80° C. while stirring. Stirring was continued at this temperature until the isocyanate content of the solution was 3.2% by weight and was constant. Thereafter, the reaction mixture was cooled to 65° C., and 85.2 parts by weight of the above-described adduct were added together with 21.8 parts by weight of trimethylolpropane (from BASF SE). The resulting reaction mixture was stirred at 65° C. until the isocyanate content of the solution had fallen to 1.0% by weight. Now 22.2% by weight of diethanolamine (from BASF SE) were added and the content of isocyanate groups was monitored until no free isocyanate groups were detectable any longer. The resulting dissolved polyurethane was admixed with 139.7 parts by weight of methoxypropanol and 43.3 parts by weight of triethylamine (from BASF SE). 30 minutes after the addition of amine, the temperature of the solution was lowered to 60° C., and then 1981 parts by weight of deionized water were added while stirring over the course of 30 minutes. The methyl ethyl ketone was distilled out of the resulting dispersion at 60° C. under reduced pressure. Thereafter, any losses of solvent and water were compensated.

(11) The dispersion of an alpha-methylstyryl-containing polyurethane thus obtained had a solids content of 29.0% by weight; the acid number was 34.0 mg KOH/g solids content and the pH was 7.0 (measured at 23° C.)

Example D-P2

Preparation of a Dispersion of a Saturated Polyesterurethane Having Isotridecyl Groups

(12) As in comparative example DP-1, a polyurethane dispersion was prepared, except that it had not alpha-methylstyryl groups but isotridecyl groups.

(13) In a reaction vessel equipped with stirrer, internal thermometer, reflux condenser and electrical heater, 440.1 parts by weight of a linear polyester polyol prepared from dimerized fatty acid (Pripol® 1012, from Uniqema), isophthalic acid (from BP Chemicals) and hexane-1,6-diol (BASF SE) (weight ratio of the starting materials: dimeric fatty acid to isophthalic acid to hexane-1,6-diol=54.00:30.02:15.98), having a hydroxyl number of 73 mg KOH/g solids and a number-average molar mass of 1379 g/mol, and also 71.1 parts by weight of dimethylolpropionic acid (from GEO Speciality Chemicals), were dissolved in 362.7 parts by weight of methyl ethyl ketone and 62.8 parts by weight of N-methylpyrrolidone under nitrogen. Added to the resulting solution at 45° C. were 294.3 parts by weight of isophorone diisocyanate (Basonat® I, from BASF SE) having an isocyanate content of 37.75% by weight. After the exothermic reaction had abated, the reaction mixture was heated gradually to 80° C. while stirring. Stirring was continued at this temperature until the isocyanate content of the solution was 3.2% by weight and was constant. Thereafter, the reaction mixture was cooled to 70° C., and 33.1 parts by weight of isotridecyl alcohol (Isotridecanol N, from BASF SE) were added together with 19.3 parts by weight of trimethylolpropane (from BASF SE) and 25.6 parts by weight of methyl ethyl ketone. The resulting reaction mixture was stirred at 70° C. until the isocyanate content of the solution had fallen to 0.8% by weight. Now 19.6% by weight of diethanolamine (from BASF SE) was added and the content of isocyanate groups was monitored until no free isocyanate groups were detectable any longer. The resulting dissolved polyurethane was admixed with 123 parts by weight of methoxypropanol and 43.8 parts by weight of triethylamine (from BASF SE). 30 minutes after the addition of amine, the temperature of the solution was lowered to 60° C., and then, after 30 minutes, 2009 parts by weight of deionized water were added while stirring. The methyl ethyl ketone was distilled out of the resulting dispersion at 60° C. under reduced pressure. Thereafter, any losses of solvent and water were compensated.

(14) The polyurethane dispersion thus obtained had a solids content of 29.0% by weight; the acid number was 34.1 mg KOH/g solids content and the pH was 7.0 (measured at 23° C.)

Example D-P3

Production of a Dispersion of a Saturated Polyetherurethane with Polytetramethylene Oxide Segments

(15) In a reaction vessel equipped with stirrer, internal thermometer, reflux condenser and electrical heater, 685.8 parts by weight of a linear alpha,omega-hydroxy-terminated polytetramethylene oxide (PolyTHF® 2000, from BASF SE) having a hydroxyl number of 56.1 mg KOH/g solids and a number-average molecular weight of 2000 g/mol, 138.0 parts by weight of dimethylolpropionic acid (from GEO Speciality Chemicals), 0.01 part by weight of dibutyltin dilaurate and 685.8 parts by weight of methyl ethyl ketone were dissolved under nitrogen at 70° C. To the resulting solution were added 418.8 parts by weight of m-tetramethylxylene diisocyanate (TMXDI® (Meta) Aliphatic Isocyanate, from Cytec) having an isocyanate content of 34.4% by weight. Subsequently, the reaction mixture was heated gradually to 80° C. while stirring and kept at this temperature until the isocyanate content of the solution was 1.8% by weight and was constant. Thereafter, 87.4 parts by weight of trimethylolpropane (from BASF SE) and 26.1 parts by weight of methyl ethyl ketone were added rapidly to the reaction mixture. The resulting reaction mixture was stirred at 80° C. until no free isocyanate groups were detectable any longer. The resulting dissolved polyurethane was admixed with 41.2 parts by weight of dimethylethanolamine and stirred for a further 60 minutes. Thereafter, the reaction mixture was transferred fully while stirring constantly over the course of 30 minutes into a second reaction vessel which had already been initially charged with 1732 parts by weight of deionized water which had been warmed beforehand to 70° C. The methyl ethyl ketone was distilled out of the resulting dispersion at 60° C. under reduced pressure. Thereafter, any losses of water were compensated.

(16) The polyurethane dispersion thus obtained had a solids content of 38.0% by weight; the acid number was 43.0 mg KOH/g solids content and the pH was 6.2 (measured at 23° C.)

Example D-P4

Production of a Known Dispersion of a Sulfur-Containing Saturated Polyesterurethane

(17) According to EP1330480B1, the polyester polyol according to preparation example 1, page 15, was used to prepare a polyurethane prepolymer according to preparation example 2, page 15, which was reacted with thiodiethanol according to example 1, page 16 “Die Herstellung eines erfindungsgemäβen Polyurethans and einer wässrigen Dispersion hiervon” [the preparation of an inventive polyurethane and an aqueous dispersion thereof], neutralized with triethylamine and then converted to an aqueous polyurethane dispersion. The methyl ethyl ketone was distilled out of the resulting dispersion at 60° C. under reduced pressure. Thereafter, any losses of water were compensated.

(18) The dispersion of a sulfur-containing polyurethane obtained in this way had a solids content of 27.3% by weight; the acid number was 34.4 mg KOH/g solids content, the neutralization level was 84% and the pH was 7.1 (measured at 23° C.)

(19) Polyurethane-Polyacrylate Copolymer Dispersions

Example D-A1

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(20) Based on patent specification DE 19948004 B4, page 27, example 2, “Die Herstellung der Primärdispersion eines erfindungsgemäβen Mischpolymerisats 1” [The preparation of the primary dispersion of an inventive copolymer 1], and patent specification EP1218434 B1, page 24, example 2, “Die Herstellung der Primärdispersion eines erfindungsgemäβen Pfropfmischpolymerisats 1” under a nitrogen atmosphere, 1937.8 parts by weight of the polyurethane dispersion according to example DP-1 were diluted with 856.9 parts by weight of deionized water and heated to 85° C. At this temperature, under standard pressure, a mixture of 160.7 parts by weight of styrene, 160.7 parts by weight of methyl methacrylate, 120.3 parts by weight of n-butyl acrylate and 120.3 parts by weight of hydroxyethyl methacrylate was added homogeneously to the dispersion while stirring over the course of 3.5 hours. With commencement of the addition of the monomer mixture, a solution of 8.4 parts by weight of tert-butyl peroxyethylhexanoate in 134.9 parts by weight of methoxypropanol was added within 4 hours. The resulting reaction mixture was stirred at 85° C. until all monomers had reacted (total monomer content (GC) based on dispersion<0.1%).

(21) During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined by means of gas chromatography (GC) (GC: 50 m silica capillary column with polyethylene glycol phase or 50 m silica capillary column with polydimethylsiloxane phase, helium carrier gas, split injector 150° C., oven temperature 40-220° C., flame ionization detector, detector temperature 275° C., isobutyl acrylate internal standard), and the highest total monomer content based on dispersion was determined after 30 min at 1.8% by weight (11.1% by weight based on vinyl monomer).

(22) The resulting primary dispersion of the copolymer had, as described in the original example, very good storage stability. The solids content thereof was 32.5% by weight, the acid number was 18.3 mg KOH/g solids content and the pH thereof was 7.2 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 104 nm. By means of gas chromatography (GC: 50 m silica capillary column with polyethylene glycol phase or 50 m silica capillary column with polydimethylsiloxane phase, helium carrier gas, split injector 250° C., oven temperature 40-220° C., flame ionization detector, detector temperature 275° C., n-propyl glycol internal standard), a content of 6.0% by weight of methyoxypropanol and 1.7% by weight of n-methylpyrrolidone was determined.

(23) After extraction of the freeze-dried polymer by means of tetrahydrofuran, the gel content was determined gravimetrically to be 71.5% by weight. For this purpose, the dispersion was freeze-dried, the mass of the freeze-dried polymer was determined, and the polymer was then extracted at 25° C. in an excess of tetrahydrofuran (ratio of tetrahydrofuran to freeze-dried copolymer=300:1) for 24 hours. The insoluble content (gel content) was isolated, dried at 50° C. in an air circulation oven for 4 hours, and then reweighed.

Example D-A2

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from a Saturated Polyesterurethane Having Isotridecyl Groups

(24) Analogously to preparation example D-A1, a primary dispersion was prepared with exchange of the polyurethane dispersion having alpha-methylstyryl groups according to preparation example D-P1 for the same weight of the polyurethane dispersion having isotridecyl groups prepared according to preparation example D-P2.

(25) During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined by means of gas chromatography analogously to example D-A1, and the highest total monomer content based on dispersion was determined after 30 min to be 2.0% by weight (12.4% by weight based on vinyl monomer).

(26) The resulting primary dispersion of the copolymer had a very good storage stability. The solids content thereof was 32.2% by weight, the acid number was 18.1 mg KOH/g solids content and the pH thereof was 7.3 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 112 nm. Analogously to example D-A1, by means of gas chromatography, a content of 5.7% by weight of methoxypropanol and 1.2% by weight of N-methylpyrrolidone was determined.

(27) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 70.2% by weight.

Example D-A3

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer (Isoprene Comonomer), Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(28) As in preparation example D-A1, a primary dispersion of a copolymer was prepared, except that 15 mol % of the vinylic monomers were exchanged for isoprene: thus, 1937.8 parts by weight of the polyurethane dispersion according to preparation example D-P1 were diluted with 857.0 parts by weight of deionized water and heated to 85° C. At this temperature, a mixture of 145.2 parts by weight of styrene, 145.2 parts by weight of methyl methacrylate, 108.7 parts by weight of n-butyl acrylate, 108.7 parts by weight of hydroxyethyl methacrylate and 54.3 parts by weight of isoprene was added homogeneously to the dispersion while stirring under gauge nitrogen pressure 3 bar over the course of 3.5 hours. With commencement of the addition of the monomer mixture, a solution of 8.4 parts by weight of tert-butyl peroxyethylhexanoate in 134.9 parts by weight of methoxypropanol was added within four hours. The resulting reaction mixture was stirred for longer at 85° C. until all monomers had reacted.

(29) The resulting primary dispersion had a very good storage stability. The solids content thereof was 32.3% by weight, the acid number was 18.3 mg KOH/g and the pH thereof was 7.2 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 115 nm. Analogously to example D-A1, by means of gas chromatography, a content of 6.0% by weight of methoxypropanol and 1.7% by weight of N-methylpyrrolidone was determined.

(30) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 70.8% by weight.

Example D-A4

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer (without Styrene Comonomer), Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(31) As in preparation example D-A1, a primary dispersion of a copolymer was prepared, except that the proportion of styrene was replaced by the same weight of methyl methacrylate and the solids content was lowered to 28%:

(32) Thus, under a nitrogen atmosphere, 1689.6 parts by weight of the polyurethane dispersion were diluted with 1133.5 parts by weight of deionized water and 142.4 parts by weight of N-methylpyrrolidone, and heated to 85° C. At this temperature, under standard pressure, a mixture of 280.3 parts by weight of methyl methacrylate, 104.9 parts by weight of n-butyl acrylate and 104.9 parts by weight of hydroxyethyl methacrylate was added homogeneously to the dispersion while stirring over the course of 3.5 hours. With commencement of the addition of the monomer mixture, a solution of 7.4 parts by weight of tert-butyl peroxyethylhexanoate in 37.0 parts by weight of methoxypropanol was added within four hours. The resulting reaction mixture was stirred for longer at 85° C. until all monomers had reacted.

(33) During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to example D-A1 by means of gas chromatography, and the highest total monomer content based on dispersion was determined after 30 min to be 1.0% by weight (7.1% by weight based on vinyl monomer).

(34) The resulting primary dispersion of the copolymer had, like the styrene-containing dispersion, very good storage stability. The solids content thereof was adjusted to 28.0% by weight; the acid number was 18.1 mg KOH/g solids content and the pH thereof was 7.2 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 102 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.8% by weight of methoxypropanol and 5.8% by weight of N-methylpyrrolidone was determined. Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 72.0% by weight.

Example D-A5

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from a Saturated, Sulfur-Containing Polyesterurethane (Solvent-Free)

(35) According to EP1330480B1, example 2, page 16, “Die Herstellung der Primärdispersion eines erfindungsgemäβen Polymergemischs” [The preparation of the primary dispersion of an inventive polymer mixture], 2285.8 parts by weight of the polyurethane dispersion according to example DP-4 were initially charged under nitrogen atmosphere and heated to 82° C. At this temperature, under standard pressure, a mixture of 118.8 parts by weight of styrene, 207.7 parts by weight of hydroxypropyl methacrylate, 59.8 parts by weight of n-butyl acrylate, 88.9 parts by weight of methyl methacrylate and 118.8 parts by weight of tert-butylcyclohexyl acrylate was added homogeneously to the dispersion while stirring over the course of 4 hours. With commencement of the addition of the monomer mixture, 29.9 parts by weight of tert-butyl peroxyethylhexanoate were added within 4.5 hours. After the initiator feed had ended, polymerization was continued at 82° C. for one hour. During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to example D-A1 by means of gas chromatography, and the highest total monomer content was determined after 30 min to be 1.6% by weight based on a 41.9% by weight dispersion (7.6% by weight based on vinyl monomer).

(36) The resulting primary dispersion was diluted further with 590.3 parts by weight of water, so as to result in a solids content as in EP1330480B1, example 2, of 34.8% by weight.

(37) The acid number was 19.6 mg KOH/g solids content and the pH of the dispersion was 7.4 (measured at 23° C.). The neutralization level was 80.2%. The particle size (z average) by means of photon correlation spectroscopy was 83 nm. The resulting dispersion did not contain any solvent. Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 0.0% by weight.

Example D-A6

Preparation of a Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from a Saturated, Sulfur-Containing Polyesterurethane, and Addition of Methoxypropanol and N-Methylpyrrolidone

(38) Analogously to example D-A5, a copolymer was prepared.

(39) The resulting primary dispersion having a solids content of 41.9% by weight, after the end of continued polymerization, was diluted further with 77.0 parts by weight of methoxypropanol, 206.5 parts by weight of N-methylpyrrolidone and 306.8 parts by weight of water, so as to result in a solids content of 34.8% by weight, analogously to comparative example D-A5.

(40) The acid number was 18.5 mg KOH/g solids content and the pH thereof was 7.2 (measured at 23° C.). The neutralization level was 80.0%. The particle size (z average) by means of photon correlation spectroscopy was 81 nm. By means of gas chromatography, analogously to example D-A1, a content of 2.2% by weight of methoxypropanol and 5.9% by weight of N-methylpyrrolidone was determined. As in example D-A5, it was not possible to determine any gel content (gel content=0.0% by weight).

Example D-B1

Preparation of an Inventive Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(41) For preparation of the primary dispersion of an inventive copolymer, under a nitrogen atmosphere, 1961.2 parts by weight of the alpha-methylstyryl-containing polyurethane dispersion according to preparation example D-P1 were diluted with 40.0 parts by weight of methoxypropanol (0.07% based on polyurethane) and 686.5 parts by weight of deionized water, and heated to 80° C. After the reactor contents had been heated to 80° C., 0.6 part by weight of ammonium peroxodisulfate dissolved in 35.7 parts by weight of deionized water was added to the reactor under standard pressure. Subsequently, while stirring continually, a mixture of 301.6 parts by weight of methyl methacrylate, 261.6 parts by weight of n-butyl acrylate, 5.6 parts by weight of allyl methacrylate (0.87 mol % based on total vinyl monomer) and 134.9 parts by weight of N-methylpyrrolidone was added homogeneously over the course of 5 hours. With commencement of the addition of the monomer mixture, a solution of 1.1 parts by weight of ammonium peroxodisulfate in 71.3 parts by weight of deionized water was likewise added within five hours.

(42) During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to example D-A1 by means of gas chromatography, and the highest total monomer content based on dispersion was determined after 30 min to be 0.5% by weight (3.1% by weight based on vinyl monomer).

(43) After the simultaneous end of the metered addition of monomer and initiator, the resulting reaction mixture was stirred at 80° C. for a further hour and then cooled to room temperature.

(44) The resulting primary dispersion of the copolymer had a very good storage stability. The solids content thereof was 32.5%, the acid number was 18.8 mg KOH/g solids content and the pH thereof was 7.0. The particle size (z average) by means of photon correlation spectroscopy was 96 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.7% by weight of methoxypropanol and 5.7% by weight of N-methylpyrrolidone was determined.

(45) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 80.3% by weight.

Example D-B2

Preparation of an Inventive Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from a Saturated Polyesterurethane Having Isotridecyl Groups

(46) Analogously to preparation example D-B1, a primary dispersion was prepared with exchange of the polyurethane dispersion having alpha-methylstyryl groups according to preparation example D-P1 for the same weight of the polyurethane dispersion having isotridecyl groups according to preparation example D-P2. During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to example D-A1 by means of gas chromatography, and the highest total monomer content based on dispersion was determined after 30 min to be 0.5% by weight (3.1% by weight based on vinyl monomer).

(47) The resulting primary dispersion of the copolymer had very good storage stability. The solids content thereof was 32.4% by weight, the acid number was 18.4 mg KOH/g solids content and the pH thereof was 6.9 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 102 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.4% by weight of methoxypropanol and 5.1% by weight of N-methylpyrrolidone was determined.

(48) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 79.1% by weight.

Example D-B3

Preparation of an Inventive Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer (Isoprene Comonomer), Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(49) As in preparation example D-B1, in accordance with the invention, a primary dispersion of a copolymer was prepared, except that 15 mol % of the vinylic monomers were exchanged for isoprene: thus, 1961.2 parts by weight of the alpha-methylstyryl-containing polyurethane dispersion according to preparation example D-P1 were diluted with 40.0 parts by weight of methoxypropanol and 686.5 parts by weight of deionized water, and heated to 80° C. At 80° C., 0.6 part by weight of ammonium peroxodisulfate dissolved in 35.7 parts by weight of deionized water was added to the reactor under gauge nitrogen pressure 3 bar. Subsequently, while maintaining the pressure and stirring continually, a mixture of 271.8 parts by weight of methyl methacrylate, 235.7 parts by weight of n-butyl acrylate, 5.9 parts by weight of allyl methacrylate (0.87 mol % based on total vinyl monomer) 55.3 parts by weight of isoprene and 134.9 parts by weight of N-methylpyrrolidone was added homogeneously over the course of six hours. With commencement of the addition of monomer mixture, a solution of 1.1 parts by weight of ammonium peroxodisulfate in 71.3 parts by weight of deionized water was likewise added within six hours. After the simultaneous end of the metered addition of monomer and initiator, the resulting reaction mixture was stirred at 80° C. for a further hour and then cooled to room temperature.

(50) The resulting primary dispersion of the graft copolymer had a very good storage stability. The solids content thereof was 32.2% by weight, the acid number of 18.8 mg KOH/g solids content and the pH thereof was 7.0 (measured at 23° C.). The particle size (z average) by means of photon correlation spectroscopy was 97 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.8% by weight of methoxypropanol and 5.6% by weight of N-methylpyrrolidone was determined.

(51) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 78.0% by weight.

Example D-B4

Preparation of an Inventive Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from an Unsaturated Polyesterurethane Having Alpha-Methylstyryl Groups

(52) To prepare the primary dispersion of an inventive copolymer, under a nitrogen atmosphere, 1689.7 parts by weight of the alpha-methylstyryl-containing polyurethane dispersion according to preparation example D-P1 were diluted with 40.3 parts by weight of methoxypropanol (0.08% based on polyurethane) and 993.8 parts by weight of deionized water, and heated to 80° C. Once the reactor contents had been heated to 80° C., 0.7 part by weight of ammonium peroxodisulfate dissolved in 46.1 parts by weight of deionized water was added to the reactor under standard pressure. Subsequently, while stirring continually, according to preparation example D-A4, a mixture of 277.6 parts by weight of methyl methacrylate, 103.8 parts by weight of n-butyl acrylate and 103.8 parts by weight of hydroxyethyl methacrylate, and additionally 4.8 parts by weight of allyl methacrylate (0.86 mol % based on total vinyl monomer) together with 145.7 parts by weight of N-methylpyrrolidone, was added homogeneously over the course of five hours. With commencement of the addition of the monomer mixture, a solution of 1.5 parts by weight of ammonium peroxodisulfate in 92.2 parts by weight of deionized water was likewise added within five hours.

(53) During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to example D-A1 by means of gas chromatography, and the highest total monomer content based on dispersion was determined after 30 min to be 0.5% by weight (3.6% by weight based on vinyl monomer).

(54) After the simultaneous end of the metered addition of monomer and initiator, the resulting reaction mixture was stirred at 80° C. for a further hour and then cooled to room temperature.

(55) The resulting primary dispersion of the copolymer had a very good storage stability. The solids content thereof was 28.0% by weight, the acid number was 18.2 mg KOH/g solids content and the pH thereof was 7.0. The particle size (z average) by means of photon correlation spectroscopy was 110 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.9% by weight of methoxypropanol and 5.9% by weight of N-methylpyrrolidone was determined. Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 81.2% by weight.

Example D-B5

Preparation of an Inventive Primary Dispersion of a Polyesterurethane-Polyacrylate Copolymer, Proceeding from a Saturated, Sulfur-Containing Polyesterurethane (Solvent-Borne)

(56) To prepare the primary dispersion of an inventive copolymer, under a nitrogen atmosphere, 2101.9 parts by weight of the polyurethane dispersion according to comparative example DP-4 were diluted with 40.1 parts by weight of methoxypropanol (0.07% based on polyurethanes) and 513.3 parts by weight of deionized water, and heated to 80° C. Once the reactor contents had been heated to 80° C., 1.1 parts by weight of ammonium peroxodisulfate dissolved in 36.4 parts by weight of deionized water were added to the reactor under standard pressure. Subsequently, while stirring continually, according to comparative examples D-A5 and D-A6, a mixture of 108.3 parts by weight of styrene, 189.4 parts by weight of hydroxypropyl methacrylate, 54.6 parts by weight of n-butyl acrylate, 81.1 parts by weight of methyl methacrylate, 108.3 parts by weight of tert-butylcyclohexyl acrylate and additionally 4.5 parts by weight of allyl methacrylate (0.87 mol % based on total vinyl monomer) together with 186.0 parts by weight of N-methylpyrrolidone was added homogeneously over the course of five hours. With commencement of the addition of the monomer mixture, a solution of 2.2 parts by weight of ammonium peroxodisulfate in 72.8 parts by weight of deionized water was likewise added within five hours. During the free-radical polymerization, at intervals of 30 minutes, the content of free monomers was determined analogously to the previous example by means of gas chromatography, and the highest total monomer content based on dispersion was determined after 30 min to be 0.6% by weight (3.7% by weight based on vinyl monomer).

(57) After the simultaneous ends of the metered addition of monomer and initiator, the resulting reaction mixture was stirred at 80° C. for a further hour and then cooled to room temperature.

(58) The resulting primary dispersion of the copolymer had good storage stability. The solids content thereof was 33.0% by weight, the acid number was 20.1 mg KOH/g solids content and the pH thereof was 7.0. The particle size (z average) by means of photon correlation spectroscopy was 72 nm. Analogously to example D-A1, by means of gas chromatography, a content of 2.1% by weight of methoxypropanol and 6.0% by weight of N-methylpyrrolidone was determined.

(59) Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 42.1% by weight.

Example D-C1

Preparation of an Inventive Primary Dispersion of a Polyetherurethane-Polyacrylate Copolymer, Proceeding from a Saturated Polyetherurethane

(60) To prepare the primary dispersion of an inventive copolymer, under a nitrogen atmosphere, 1496.7 parts by weight of a polytetramethylene oxide-containing polyurethane dispersion according to preparation example D-P3 were diluted with 40.0 parts by weight of methoxypropanol (0.07% based on polyurethane) and 1150.9 parts by weight of deionized water, and heated to 80° C. Once the reactor contents had been heated to 80° C., 0.6 part by weight of ammonium peroxodisulfate dissolved in 35.7 parts by weight of deionized water was added to the reactor under standard pressure. Subsequently, while stirring continually, a mixture of 301.6 parts by weight of methyl methacrylate, 261.6 parts by weight of n-butyl acrylate, 5.6 parts by weight of allyl methacrylate (0.87 mol %) and 134.9 parts by weight of N-methylpyrrolidone was added homogeneously over the course of six hours. With commencement of the addition of the monomer mixture, a solution of 1.1 parts by weight of ammonium peroxodisulfate in 71.3 parts by weight of deionized water was likewise added within six hours. After the simultaneous end of the metered addition of monomer and initiator, the resulting reaction mixture was stirred at 80° C. for a further hour and then cooled to room temperature.

(61) The resulting primary dispersion of the copolymer had very good storage stability. The solids content thereof was 32.8% by weight, the acid number was 23.2 mg KOH/g solids content and the pH thereof was 6.2. Analogously to example D-A1, by means of gas chromatography, a content of 1.1% by weight of methoxypropanol and 3.9% by weight of N-methylpyrrolidone was determined. The particle size (z average) by means of photon correlation spectroscopy was 103 nm. Analogously to example D-A1, the gel content was determined gravimetrically after extraction by means of tetrahydrofuran to be 85.2% by weight.

(62) Transmission Electron Microscopy on Unpigmented Polymer Films of Isoprene-Containing Polyurethane-Polyacrylate Copolymers

(63) To examine the morphology, free films of the primary dispersions were produced, and these were contrasted by means of osmium tetroxide and examined with the aid of a transmission electron microscope.

(64) For this purpose, one drop of the primary dispersion in each case was added to 10 ml of deionized water and stirred well. Subsequently, the surface of a copper grid was used to take up one drop of the highly diluted primary dispersion thus formed, and the polymer film was dried under high vacuum. This was followed by the contrasting of the film in an osmium tetroxide-enriched atmosphere in a closed vessel.

(65) The electron microscopy analysis was effected in transmission (tab. 1, FIG. 1). This involved visualizing spherical particles having particle sizes less than 150 nm in a continuous matrix of dark or light appearance, which corresponds to a core-shell morphology:

(66) TABLE-US-00001 TABLE 1 Transmission electron microscopy of unpigmented polymer films containing isoprene-containing polyurethane (PU)- polyacrylate (PAC) copolymers Polyurethane (PU)-polyacrylate (PAC) copolymer Preparation D-A3 D-B3 example Contains polyurethane D-P1 D-P1 dispersion Polyurethane in % solids 50 50 contents based on overall solids Isoprene content in mol % 15 15 in the polyacrylate copolymer Polymer film (unpigmented, dried under high vacuum) Transmission electron microscopy (Contrasting of polyacrylate: OsO4) Appearance of continuous phase Light Dark Appearance of discontinuous phase Dark Light Morphology Core- Core- shell shell

(67) The above experiment shows that the core-shell structure of the copolymers of the inventive dispersions (D-B3) is the inverse of the structure of the copolymers known from the prior art (D-A3).

(68) Production of Silver-Colored Waterborne Basecoats

(69) The components listed in tables 2a, 2b, 3a and 3b under “aqueous phase” are stirred together in the sequence specified to give an aqueous mixture. In the next step, components listed under “organic phase” are used to produce an organic mixture. The organic mixture is added to the aqueous mixture. Then the mixture is stirred for 10 min and adjusted with the aid of deionized water and N,N-dimethylethanolamine (from BASF SE) to a pH of 8.0 and spraying viscosity.

(70) TABLE-US-00002 TABLE 2a Production of silver-colored waterborne basecoats for the determination of the pinholing limit and pinhole count, and the visibility of crosses ground in a multicoat paint system Designation of the waterborne basecoat BL- BL- BL- BL- BL- BL- A0 A1 A2 A3 A4 A5 Component Parts by weight AQUEOUS PHASE Aqueous solution of 3% sodium-lithium-magnesium 22.0 22.0 22.0 22.0 22.0 22.0 sheet silicate solution Laponite ® RD (from Rockwood Additives) and 3% Pluriol ® P900 (from BASF SE) Deionized water 2.0 2.0 2.0 2.0 2.0 2.0 Foamstar MF 324 (from Cognis) 0.7 0.0 0.0 0.0 0.0 0.0 1-Octanol (from BASF SE) 1.5 0.0 0.0 0.0 0.0 0.0 Deionized water 2.3 2.3 2.3 2.3 2.3 2.3 Polyurethane acrylate, prepared according to example D, 4.6 4.6 4.6 4.6 4.6 4.6 pages 7-8, of DE 4437535 A1 TMDD 50% BG (from BASF SE), 50% solution of 0.9 0.9 0.9 0.9 0.9 0.9 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol Polyester, prepared according to example D, page 10, 1.0 1.0 1.0 1.0 1.0 1.0 of DE 4009858 C2 Butylglycol (from BASF SE) 1.8 1.8 1.8 1.8 1.8 1.8 Luwipal ® 052 (from BASF SE), melamine-formaldehyde 5.0 5.0 5.0 5.0 5.0 5.0 resin TMDD 50% BG (from BASF SE), 50% solution of 0.7 0.7 0.7 0.7 0.7 0.7 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol 10% solution of N,N-dimethylethanolamine (from 0.5 0.5 0.5 0.5 0.5 0.5 BASF SE) in water Pluriol ® P 900 (from BASF SE), polypropylene oxide 0.7 0.7 0.7 0.7 0.7 0.7 Isopropanol (from BASF SE) 3.3 3.3 3.3 3.3 3.3 3.3 Deionized water 1.0 1.0 1.0 1.0 1.0 1.0 3.0% Viscalex ® HV30 (from BASF SE)-solution in water 3.0 3.0 3.0 3.0 3.0 3.0 (rheology modifier) Deionized water 1.0 1.0 1.0 1.0 1.0 1.0 50.0% solution of DSX 1550 (from Cognis) in butylglycol 0.4 0.4 0.4 0.4 0.4 0.4 (rheology agent) Deionized water 1.0 1.0 1.0 1.0 1.0 1.0 Polyurethane-polyacrylate copolymer According to preparation example D-A1 15.8 15.8 According to preparation example D-A2 15.9 According to preparation example D-A4 18.3 According to preparation example D-A5 14.8 According to preparation example D-A6 14.8 Deionized water 0.8 1.0 1.0 0.5 1.0 1.0 10% Dimethylethanolamine in water 0.4 0.4 0.4 0.4 0.4 0.4 TMDD 50% BG (from BASF SE), 50% solution of 0.5 0.5 0.5 0.5 0.5 0.5 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol Deionized water 0.0 2.0 2.0 0.0 3.0 3.0 Isopar L (from ExxonMobil Chemical), solvent 2.0 2.0 2.0 2.0 2.0 2.0 (isoparaffinic hydrocarbon) Propanol (from BASF SE) 0.9 0.9 0.9 0.9 0.9 0.9 Deionized water 1.5 1.5 1.5 1.5 1.5 1.5 ORGANIC PHASE Mixture of two commercially available aluminum 6.5 6.5 6.5 6.5 6.5 6.5 pigments, STAPA Hydrolux 1071 Aluminum and STAPA Hydrolux VP No. 56450/G Aluminum (from Eckart Effect Pigments) Butylglycol (from BASF SE) 8.4 8.4 8.4 8.4 8.4 8.4 Polyester, prepared according to example D, page 10, of 2.0 2.0 2.0 2.0 2.0 2.0 DE 4009858 C2

(71) TABLE-US-00003 TABLE 2b Production of silver-colored waterborne basecoats for the determination of the pinholing limit and pinhole count, and the visibility of crosses ground in a multicoat paint system Designation of the waterborne basecoat BL- BL- BL- BL- B1 B2 B3 B4 Component Parts by weight AQUEOUS PHASE Aqueous solution of 3% sodium-lithium- 22.0 22.0 22.0 22.0 magnesium sheet silicate solution Laponite ® RD (from Rockwood Additives) and 3% Pluriol ® P900 (from BASF SE) Deionized water 2.0 2.0 2.0 2.0 Foamstar MF 324 (from Cognis) 0.0 0.0 0.0 0.0 1-Octanol (from BASF SE) 0.0 0.0 0.0 0.0 Deionized water 2.3 2.3 2.3 2.3 Polyurethane acrylate, prepared 4.6 4.6 4.6 4.6 according to example D, pages 7-8, of DE 4437535 A1 TMDD 50% BG (from BASF SE), 0.9 0.9 0.9 0.9 50% solution of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol Polyester, prepared according to 1.0 1.0 1.0 1.0 example D, page 10, of DE 4009858 C2 Butylglycol (from BASF SE) 1.8 1.8 1.8 1.8 Luwipal ® 052 (from BASF SE), 5.0 5.0 5.0 5.0 melamine-formaldehyde resin TMDD 50% BG (from BASF SE), 0.7 0.7 0.7 0.7 50% solution of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3)in butylglycol 10% solution of N,N- 0.5 0.5 0.5 0.5 dimethylethanolamine (from BASF SE) in water Pluriol ® P 900 (from BASF SE), 0.7 0.7 0.7 0.7 polypropylene oxide Isopropanol(from BASF SE) 3.3 3.3 3.3 3.3 Deionized water 1.0 1.0 1.0 1.0 3.0% Viscalex ® HV30(from BASF SE)- 3.0 3.0 3.0 3.0 solution in water (rheology modifier) Deionized water 1.0 1.0 1.0 1.0 50.0% solution of DSX 1550 (from 0.4 0.4 0.4 0.4 Cognis) in butylglycol (rheology agent) Deionized water 1.0 1.0 1.0 1.0 Polyurethane-polyacrylate copolymer According to preparation example D-B1 15.8 According to preparation example D-B2 15.8 According to preparation example D-B4 18.3 According to preparation example D-B5 15.6 Deionized water 1.0 1.0 0.5 1.0 10% Dimethylethanolamine in water 0.4 0.4 0.4 0.4 TMDD 50% BG (from BASF SE), 50% 0.5 0.5 0.5 0.5 solution of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol Deionized water 2.0 2.0 0.0 2.2 Isopar L (from ExxonMobil Chemical), 2.0 2.0 2.0 2.0 solvent (isoparaffinic hydrocarbon) Propanol (from BASF SE) 0.9 0.9 0.9 0.9 Deionized water 1.5 1.5 1.5 1.5 ORGANIC PHASE Mixture of two commercially available 6.5 6.5 6.5 6.5 aluminum pigments, STAPA Hydrolux 1071 Aluminum and STAPA Hydrolux VP No. 56450/G Aluminum (from Eckart Effect Pigments) Butylglycol (from BASF SE) 8.4 8.4 8.4 8.4 Polyester, prepared according to 2.0 2.0 2.0 2.0 example D, page 10, of DE 4009858 C2

(72) TABLE-US-00004 TABLE 3a Production of silver-colored waterborne basecoats for the determination of cross-cutting Designation of the waterborne basecoat BL- BL- BL- BL- BL- BL- BL- C1 C2 C3 C4 C5 C6 C7 Component Parts by weight AQUEOUS PHASE Aqueous solution of 3% sodium-lithium-magnesium 20.0 20.0 20.0 20.0 20.0 20.0 20.0 sheet silicate solution Laponite ® RD (from Rockwood Additives) and 3% Pluriol ® P900 (from BASF SE) Deionized water 6.2 6.2 6.2 6.2 6.2 6.2 6.2 Polyurethane acrylate, prepared according to example D, 4.9 4.9 4.9 4.9 4.9 4.9 4.9 pages 7-8, of DE 4437535 A1 TMDD 50% BG (from BASF SE), 50% solution of 0.9 0.9 0.9 0.9 0.9 0.9 0.9 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol Butylglycol (BASF SE) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Luwipal ® 052 (from BASF SE), melamine-formaldehyde 5.7 5.7 5.7 5.7 5.7 5.7 5.7 resin TMDD 50% BG (from BASF SE), 50% solution of 0.8 0.8 0.8 0.8 0.8 0.8 0.8 2,4,7,9-tetramethyl-5-decyne-4,7-diol (CAS No. 126-86-3) in butylglycol 10% solution of N,N-dimethylethanolamine (from 0.6 0.6 0.6 0.6 0.6 0.6 0.6 BASF SE) in water Pluriol ® P 900 (from BASF SE),polypropylene oxide 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Deionized water 2.2 2.2 2.2 2.2 2.2 2.2 2.2 3.0% Viscalex ® HV30 (from BASF SE)-solution in 3.0 3.0 3.0 3.0 3.0 3.0 3.0 water (rheology modifier) Deionized water 1.1 1.1 1.1 1.1 1.1 1.1 1.1 50.0% solution of DSX 1550 (from Cognis) in butylglycol 0.2 0.2 0.2 0.2 0.2 0.2 0.2 (rheology agent) Deionized water 1.1 1.1 1.1 1.1 1.1 1.1 1.1

(73) TABLE-US-00005 TABLE 3b Production of silver-colored waterborne basecoats for the determination of cross-cutting Designation of the waterborne basecoat BL- BL- BL- BL- BL- BL- BL- C1 C2 C3 C4 C5 C6 C7 Component Parts by weight Polyurethane-polyacrylate copolymer According to preparation example D-A1 18.8 According to preparation example D-A2 19.0 According to preparation example D-A4 21.8 According to preparation example D-B1 18.8 According to preparation example D-B2 18.9 According to preparation example D-B4 21.7 According to preparation example D-C1 18.6 Deionized water 1.1 1.0 0.0 1.1 1.1 0.0 1.3 10% Dimethylethanolamine in water 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Isopar L (from ExxonMobile Chemical), solvent 2.1 2.1 2.1 2.1 2.1 2.1 2.1 (isoparaffinic hydrocarbon) Deionized water 5.0 5.0 3.2 5.0 5.0 3.2 5.0 ORGANIC PHASE Mixture of two commercially available aluminum 5.6 5.6 5.6 5.6 5.6 5.6 5.6 pigments, STAPA Hydrolux 1071 Aluminum and STAPA Hydrolux VP No. 56450/G Aluminum (from Eckart Effect Pigments) Butylglycol (from BASF SE) 6.6 6.6 6.6 6.6 6.6 6.6 6.6 Mixing varnish, prepared according to preparation 5.5 5.5 5.5 5.5 5.5 5.5 5.5 example 1 of WO 2006/040284 A1 (page 14 lines 15-27), according to preparation example 1 consisting of a graft copolymer, deionized water, Surfynol ® 100 (from Air Products), Hydropalat ® 3037 (from Cognis, a polyoxylene derivative of castor oil) and 1-propoxy-2-propanol
Comparative Experiments Between the Waterborne Basecoats BL-A0 to BL-A5 with the Inventive Waterborne Basecoats BL-B1 to BL-B4 with Regard to Pinholing Limit, Pinhole Count and Visibility of Crosses Ground in Multicoat Paint Systems

(74) To determine the pinholing limit, the pinhole count and the capacity to conceal ground crosses, multicoat paint systems comprising waterborne basecoats BL-A0 to BL-B4 were examined.

(75) While waterborne basecoat BL-A0 contained Foamstar MF 324 (from Cognis) and 1-octanol (from BASF SE), all other waterborne basecoats BL-A1 to BL-B4 were free of these two components.

(76) To determine the pinholing limit and the pinhole count, the multicoat paint systems were produced with the waterborne basecoats according to the following general method:

(77) A steel panel of dimensions 30 cm×50 cm coated with a primer-surfacer coat was provided with an adhesive strip along one longitudinal edge, in order to be able to determine the differences in layer thickness after the coating. The waterborne basecoat was applied electrostatically in wedge format. The resulting waterborne basecoat film was flashed off at room temperature for one minute and then dried at 70° C. in an air circulation oven for 10 minutes. A customary two-component clearcoat was applied to the dried waterborne basecoat film. The resulting clearcoat film was flashed off at room temperature for 20 minutes. Subsequently, the waterborne basecoat film and clearcoat film were cured jointly in an air circulation oven at 140° C. for 20 minutes. The layer thickness of the cured clearcoat film was constant (±1 μm) over the entire sheet, with a clearcoat film thickness of 38 to 42 μm.

(78) After the visual assessment of the pinholes in the resulting wedge-shaped multicoat paint system, the coat thickness for the pinholing limit was determined.

(79) In addition, the capacity to conceal ground crosses was compared:

(80) For this purpose, a coiled panel of dimensions 30×60 cm was painted with a primer-surfacer and the primer-surfacer was baked at 160° C. over a period of 20 minutes. A piece of abrasive paper having 800 particles per cm.sup.2 on the surface was used to grind a cross into the sheet, which had a depth of 2-4 μm and a furrow width of 2 cm. Subsequently, the appropriate basecoat was applied with a coat thickness of 8-12 μm. Subsequently, the resulting panel was dried at 80° C. for 10 minutes, and a customary and known two-component clearcoat was applied to the dried waterborne basecoat film. Subsequently, the waterborne basecoat film and clearcoat film were cured jointly in an air circulation oven at 140° C. for 20 minutes.

(81) The visibility of the cross ground in the multicoat paint system was determined visually and assessed on a scale from 1 to 5. On this scale, high numerical values indicate good visibility of the ground cross and low numerical values good concealment of the ground crosses.

(82) Tables 4 and 5 give an overview of the results of the determination of pinholing limit, pinhole count and capacity to conceal ground crosses for the multicoat paint systems:

(83) TABLE-US-00006 TABLE 4 Results of the determination of pinholing limit, pinhole count and capacity to conceal ground crosses for the multicoat paint systems based on the waterborne basecoats BL-A0 to BL-A3 and BL-B1 to BL-B3 Waterborne basecoat BL- BL- BL- BL- BL- BL- BL- A0 A1 A2 A3 B1 B2 B3 Polyurethane D-P1 D-P1 D-P2 D-P1 D-P1 D-P2 D-P1 dispersion Copolymer D-A1 D-A1 D-A2 D-A4 D-B1 D-B2 D-B4 Foamstar MF324/ Yes No No No No No No 1-octanol Pinholing limit/ 16 9 10 16 21 21 19 10.sup.-6 m Pinhole count 17 127 145 101 11 7 23 Visibility of ground 4 4 4 4 3 3 3 cross

(84) TABLE-US-00007 TABLE 5 Results of the determination of pinholing limit, pinhole count and capacity to conceal ground crosses for the multicoat paint systems based on the waterborne basecoats BL-A4, BL-A5, and BL-B4 Waterborne basecoat BL-A4 BL-A5 BL-B4 Polyurethane dispersion D-P4 D-P4 D-P4 Copolymer D-A5 D-A6 D-B5 Pinholing limit/10.sup.−6 m 14 17 27 Pinhole count >200 >200 90 Visibility of ground cross 4 4 3
Comparative Tests Between the Waterborne Basecoats BL-C1 to BL-C3 and the Inventive Waterborne Basecoats BL-C4 to BL-C7 with Regard to the Improvement in Cross-Cut Results

(85) To determine the cross-cut, multicoat paint systems comprising comparative waterborne basecoats BL-C1 to BL-C3 and the inventive waterborne basecoats BL-C4 to BL-C7 were examined.

(86) This was done using a panel of dimensions 10 cm×20 cm, which had a primer-surfacer coat of a commercial standard primer-surfacer as the substrate. In the production of this substrate, the primer-surfacer was dried intermediately at 80° C. over a period of 10 min and then baked at 190° C. over a period of 30 min.

(87) First of all, a basecoat material according to table 6 was applied pneumatically in each case to this panel. After the basecoat material had been flashed off at room temperature for 1 min, the basecoat material was dried intermediately in an air circulation oven at 70° C. over the course of 10 min. Subsequently, the two-component clearcoat material FF99-0345 commercially available from BASF was likewise applied pneumatically and, after flashing off at room temperature for 20 min, the two layers were baked at a temperature of 160° C. over a period of 30 min. The result was an overbaked multicoat paint system.

(88) After cooling the overbaked multicoat paint system, the paint systems were abraded. Subsequently, the particular basecoat material according to table 3 was applied pneumatically. After the basecoat material had been flashed off at room temperature for 1 minute, the basecoat material was dried intermediately in an air circulation oven at 70° C. over the course of 10 min. Subsequently, the two-component refinishing clearcoat material composed of FF23-0500 and SC29-0093 commercially available from BASF was applied pneumatically and, after flashing off at room temperature for 20 min, the two layers were baked at a temperature of 80° C. over a period of 30 min. The result was a refinished paint system.

(89) The adhesion was examined on the underbaked refinished paint system atop the abraded, overbaked multicoat paint system by the cross-cut test.

(90) The cross-cut test was conducted to DIN 2409. The assessment of the results of the cross-cut test was conducted to DIN EN ISO 2409.

(91) Table 6 gives an overview of the results of the cross-cut test with comparison of the various waterborne basecoat materials:

(92) TABLE-US-00008 TABLE 6 Results of the cross-cut test on a refinished paint system atop an overbaked multicoat paint system based on the waterborne basecoat materials BL-C1 to BL-C3 compared with the inventive waterborne basecoats BL-C4 to BL-C7 Waterborne basecoat material BL- BL- BL- BL- BL- BL- BL- C1 C2 C3 C4 C5 C6 C7 Polyurethane D-P1 D-P2 D-P1 D-P1 D-P1 D-P2 D-P3 dispersion Copolymer D-A1 D-A2 D-A4 D-B1 D-B2 D-B4 D-C1 Cross-cut (mark) 4 4 4 2.5 2.5 2.5 1