Aqueous dispersions containing multistage produced polymers and coating agent compositions containing the same

Abstract

The invention relates to aqueous dispersions comprising multistage-prepared polymers, and also to coating material compositions comprising them, preparable by multistage polymerization of olefinically unsaturated monomers, using an emulsifier and a water-soluble initiator, under conditions of starved feed polymerization, and using particular monomer mixtures in the individual stages. The invention also relates to a pigmented aqueous basecoat material comprising the aqueous dispersion of the invention, to the use of the aqueous dispersion of the invention in aqueous basecoat materials for improving adhesion, to a process for producing a multicoat paint system on a substrate, and to a multicoat paint system produced in accordance with the stated process.

Claims

1. An aqueous dispersion, comprising a seed-core-shell polymer, comprising: a seed polymer comprising a polymerized mixture of olefinically unsaturated monomers A; a core polymer comprising a polymerized mixture of olefinically unsaturated monomers B; and a shell polymer comprising a polymerized mixture of olefinically unsaturated monomers C; wherein a particle size of the seed-core-shell polymer is from 150 to 280 nm, a mass of the monomers mixture A is 1 to 10% based on the total mass of the monomer mixtures A, B and C, the mixture of olefinically unsaturated monomers A comprises at least 50.0 wt % of one or more monomers having a solubility in water of <0.5 g/l at 25 C., a glass transition temperature of the seed polymer is from 10 to 55 C., the mixture of olefinically unsaturated monomers B comprises at least one polyolefinically unsaturated monomer, a glass transition temperature of the core polymer is from 35 to 12 C., a glass transition temperature of the shell polymer is from 50 to 15 C., wherein the seed-core-shell polymer is obtained by a process comprising: i) polymerizing the mixture of olefinically unsaturated monomers A by emulsion polymerization in water, in the presence of an emulsifier and a water-soluble initiator to obtain the seed polymer wherein a monomers A concentration of 6 wt % is not exceeded in the seed polymerizing reaction mixture; ii) polymerizing the mixture of olefinically unsaturated monomers B by emulsion polymerization in water, in the presence of an emulsifier and a water-soluble initiator, in the presence of the seed polymer to obtain a seed-core polymer having a particle size of 130 to 200 nm, where a monomers concentration of 6.0 wt % in the seed-core polymnerization mixture is not exceeded throughout the reaction period; iii) polymerizing the mixture of olefinically unsaturated monomers C by emulsion polymerization in water, in the presence of an emulsifier and a water-soluble initiator, in the presence of the seed-core polymer to obtain the aqueous seed-core-shell polymer dispersion, where a monomers concentration of 6.0 wt % in the seed-core-shell polymerization solution is not exceeded throughout the reaction period; and iv) adjusting the pH of the seed-core-shell polymer dispersion to a pH of 7.5 to 8.5.

2. The seed-core-shell polymer of claim 1, wherein: the mass of the monomer mixture B, based on the total mass of the monomer mixtures A, B and C, is 60 to 80%; and the mass of the monomer mixture C, based on the total mass of the monomer mixtures A, B and C, is 10 to 30%.

3. The seed-core-shell polymer of claim 1, wherein the emulsifier under i), ii), and iii) is an ethoxylated or propoxylated alkanol having 10 to 40 carbon atoms.

4. The seed-core-shell polymer of claim 1, wherein the monomer mixture A comprises at least one monounsaturated ester of (meth)acrylic acid having an unsubstituted alkyl radical and at least one vinylically monounsaturated monomer having an aromatic radical on the vinyl group.

5. The seed-core-shell polymer of claim 1, wherein the monomer mixture B comprises at least one polyolefinically unsaturated monomer, at least one monounsaturated ester of (meth)acrylic acid having an unsubstituted alkyl radical, and at least one vinylically monounsaturated monomer having an aromatic radical on the vinyl group.

6. The seed-core-shell polymer of claim 1, wherein the monomer mixture C comprises at least one alpha-beta unsaturated carboxylic acid, at least one monounsaturated ester of (meth)acrylic acid having an alkyl radical substituted by one or more hydroxyl groups and at least one monounsaturated ester of (meth)acrylic acid having an unsubstituted alkyl radical.

7. A pigmented aqueous basecoat material, comprising at least one seed-core-shell polymer of claim 1.

8. The pigmented aqueous basecoat material of claim 7, wherein a sum total of the weight percentage fractions, based on the total weight of the pigmented aqueous basecoat material, of all seed-core-shell polymers of the invention is 0.1 to 30 wt %.

9. The pigmented aqueous basecoat material of claim 7, further comprising at least one polyurethane resin.

10. The pigmented aqueous basecoat material of claim 7, further comprising a polyurethane resin comprising hydroxyl groups, which is grafted by olefinically unsaturated monomers and further comprising a melamine resin.

11. A pigmented aqueous basecoat material, comprising the seed-core-shell polymer of claim 1.

12. A process for producing a multicoat paint system, comprising: (1) applying the pigmented aqueous basecoat material of claim 7 to a substrate; (2) forming a basecoat polymer film from the coating material applied in stage (1); (3) applying a clearcoat material to the basecoat film to obtain a clearcoat film on the basecoat film; and subsequently (4) curing the basecoat film together with the clearcoat film.

13. The process of claim 12, wherein the substrate from stage (1) is a multicoat paint system possessing defect sites.

14. The process of claim 13, comprising repeating the steps (1)-(4) on the multicoat paint system as the substrate possessing defect sites.

Description

EXAMPLES

(1) Examples of Binder Syntheses

(2) 1.1 Preparation of the Seed-core-shell Acrylate BM2 to BM7

(3) 80 wt % of items 1 and 2 in table 1.1 are placed into a steel reactor (5 L volume) with reflux condenser, and heated to 80 C. The remaining fractions of the components listed under initial charge in table 1.1 are premixed in a separate vessel. This mixture and the initiator solution (table 1.1, items 5 and 6) are added dropwise to the reactor over 20 minutes, a concentration of the monomers of 6.0% by weight not being exceeded in the reaction solution throughout the reaction time. This is followed by stirring for 30 minutes.

(4) The components indicated under mono 1 in table 1.1 are premixed in a separate vessel. This mixture is added dropwise to the reactor over 2 hours, a concentration of the monomers of 6.0% by weight not being exceeded in the reaction solution throughout the reaction time. This is followed by 1 hour of stirring.

(5) The components indicated under mono 2 in table 1.1 are premixed in a separate vessel. This mixture is added dropwise to the reactor over 1 hour, a concentration of the monomers of 6.0% by weight not being exceeded in the reaction solution throughout the reaction time. This is followed by 2 hours of stirring.

(6) The reaction mixture is thereafter cooled to 60 C. and the neutralizing mixture (table 1.1, items 20, 21, and 22) is premixed in a separate vessel. The neutralizing mixture is added dropwise to the reactor over 40 minutes, the pH of the reaction solution being set to a pH from 7.5 to 8.5. The reaction product is subsequently stirred for 30 minutes more, cooled to 25 C., and filtered.

(7) TABLE-US-00001 TABLE 1.1 Seed-core-shell acrylates BM2 to BM7 BM2* BM3* BM4 BM5 BM6 BM7 Initial charge 1 DI water 41.81 41.81 41.81 41.81 41.81 41.81 2 EF 800 0.18 0.18 0.18 0.18 0.18 0.18 3 Styrene 0.68 0.93 0.93 0.93 0.23 0.23 4 n-Butyl acrylate 0.48 0.23 0.23 0.23 0.93 0.93 Initiator solution 5 DI water 0.53 0.53 0.53 0.53 0.53 0.53 6 APS 0.02 0.02 0.02 0.02 0.02 0.02 Mono 1 7 DI water 12.78 12.78 12.78 12.78 12.78 12.78 8 EF 800 0.15 0.15 0.15 0.15 0.15 0.15 9 APS 0.02 0.02 0.02 0.02 0.02 0.02 10 Styrene 5.61 5.61 12.41 12.41 12.41 12.41 11 n-Butyl acrylate 13.6 13.6 6.8 6.8 6.8 6.8 12 1,6-HDDA 0.34 0.34 0.34 0.34 0.34 0.34 Mono 2 13 DI water 5.73 5.73 5.73 5.73 5.73 5.73 14 EF 800 0.07 0.07 0.07 0.07 0.07 0.07 15 APS 0.02 0.02 0.02 0.02 0.02 0.02 16 Methacrylic acid 0.71 0.71 0.71 0.71 0.71 0.71 17 2-HEA 0.95 0.95 0.95 0.95 0.95 0.95 18 n-Butyl acrylate 3.74 1.87 3.74 1.87 3.74 1.87 19 MMA 0.58 2.45 0.58 2.45 0.58 2.45 Neutralizing 20 DI water 6.48 6.48 6.48 6.48 6.48 6.48 21 Butyl glycol 4.76 4.76 4.76 4.76 4.76 4.76 22 DMEA 0.76 0.76 0.76 0.76 0.76 0.76 pH 8.2 8.1 7.9 8.3 8.4 8.1 *inventive

(8) The solids content was determined for the purpose of reaction monitoring. The results are reported in table 1.2:

(9) TABLE-US-00002 TABLE 1.2 Solids content of the seed-core-shell acrylates BM2 to BM7 BM2* BM3* BM4 BM5 BM6 BM7 Solids content [%] 25.5 25.5 25.5 26 27.4 26.1 *inventive

(10) After each stage, the particle size was determined by means of dynamic light scattering in accordance with DIN ISO 13321. The results are reproduced in table 1.3.

(11) TABLE-US-00003 TABLE 1.3 Particle sizes in nm of the seed-core-shell acrylates BM2 to BM7 BM2* BM3* BM4 BM5 BM6 BM7 i After initial charge 90 70 70 70 120 120 ii After Mono 1 150 160 160 180 150 160 iii After Mono 2 190 230 230 250 220 200 iiii After neutralizing 240 290 275 300 250 245 *inventive

(12) Each of the stated monomer mixtures was polymerized individually and thereafter the glass transition temperature was determined by means of DSC in accordance with DIN standard 53765. Also determined was the glass transition temperature for the overall polymer, after neutralization, by means of DSC in accordance with DIN standard 53765.

(13) The results are reported in table 1.4.

(14) TABLE-US-00004 TABLE 1.4 Glass transition temperatures in C. of individual stages of the seed-core-shell acrylates BM2 to BM7 BM2* BM3* BM4 BM5 BM6 BM7 i Initial charge 30 50 48 50 9 9 ii Mono 1 11 12 45 45 47 48 iii Mono 2 4 6 4 4 5 4 Overall polymer 9 7 46 47 45 46 *inventive
1.2 Preparation of a Three-stage Acrylate BM8 (as Per Korea Polym. J., Vol. 7, No. 4, pp. 213-222)

(15) Components 1 to 4 from table 1.5 are placed into a steel reactor (5 L volume) with reflux condenser, and heated to 80 C. The initiator solution (table 1.5, items 5 and 6) is added dropwise to the reactor over 5 minutes. This is followed by stirring for 30 minutes.

(16) The components indicated under mono 1 in table 1.5 are premixed in a separate vessel. This mixture is added dropwise to the reactor over 2 hours. This is followed by 1 hour of stirring.

(17) The components indicated under mono 2 in table 1.5 are premixed in a separate vessel. This mixture is added dropwise to the reactor over 1 hour. This is followed by 1 hour of stirring.

(18) The reaction mixture is thereafter cooled to 60 C. and the neutralizing mixture (table 1.2, items 21 and 22) is premixed in a separate vessel. The neutralizing mixture is added dropwise to the reactor over 40 minutes. The reaction product is subsequently stirred for 30 minutes more and cooled to 25 C.

(19) TABLE-US-00005 TABLE 1.5 Multistage acrylate BM8 BM8 Initial charge 1 DI water 43.54 2 Rhodapex CO 436 0.16 3 Styrene 0.5 4 Ethyl acrylate 0.55 Initiator solution 5 DI water 0.55 6 APS 0.02 Mono 1 7 DI water 13.31 8 Rhodapex CO 436 0.13 9 APS 0.02 10 Styrene 5.84 11 Ethyl acrylate 11.05 12 1,6-HDDA 0.35 Mono 2 13 DI water 5.97 14 Rhodapex CO 436 0.06 15 APS 0.02 16 Methacrylic acid 0.74 17 2-HEA 0.99 18 Ethyl acrylate 3.04 19 MMA 0.6 Neutralizing 20 DI water 6.75 21 Butyl glycol 4.96 22 DMEA 0.79 pH 8.1

(20) The solids content was 23.4%.

(21) After each stage, the particle size was determined by means of dynamic light scattering in accordance with DIN ISO 13321. The results are reproduced in table 1.6.

(22) TABLE-US-00006 TABLE 1.6 Particle sizes in nm of the multistage acrylate BM8 BM8 i After initial charge 110 ii After Mono 1 196 iii After Mono 2 223 iiii After neutralizing 310

(23) Each of the stated monomer mixtures was polymerized individually and thereafter the glass transition temperature was determined by means of DSC in accordance with DIN standard 53765. Also determined was the glass transition temperature for the overall polymer, after neutralization, by means of DSC in accordance with DIN standard 53765.

(24) The results are reported in table 1.7.

(25) TABLE-US-00007 TABLE 1.7 Glass transition temperatures in C. of individual stages of the multistage acrylate BM8 BM8 i Initial charge 32 ii Mono 1 26 iii Mono 2 35 Overall polymer 26
Examples of Paint Formulations
2.1 Preparation of a Noninventive Waterborne Basecoat Material A1 Based on a Polyurethane Resin

(26) The components listed under aqueous phase in table 2.1 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and then a pH of 8 and a spray viscosity of 90-95 mPa.Math.s under a shearing load of 1000 s.sup.1, as measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C. are set using deionized water and dimethylethanolamine.

(27) TABLE-US-00008 TABLE 2.1 Waterborne basecoat material A1 (not inventive) Component Parts by weight Aqueous phase 3% strength NaMg phyllosilicate solution 14.85 Deionized water 11.04 n-Butoxypropanol 1.35 2-Ethylhexanol 1.74 Polyurethane resin, prepared as per international patent application 17.94 WO 92/15405, page 15, lines 23-28 Polyester prepared as per example D, column 16, lines 37-59 of DE 2.05 40 09 858 A1 3 wt % strength aqueous Rheovis AS 1130 solution (Rheovis AS 3.72 1130 available from BASF SE) Melamine-formaldehyde resin (Cymel 303 from Allnex) 6.06 10% strength dimethylethanolamine in water 0.52 Pluriol P900 from BASF SE 1.74 BYK-347 from Altana/BYK-Chemie GmbH 0.35 Polyurethane-modified polyacrylate, prepared as per page 7, line 55 3.46 to page 8, line 23 of DE 4437535 A1 Isopropanol 1.48 Triglycol 1.46 50 wt % strength solution of Rheovis PU1250 in butyl glycol 0.63 (Rheovis PU1250 available from BASF SE) 30 wt % strength aqueous Rheovis AS 1130 solution, available from 1.00 BASF SE 10% strength dimethylethanolamine in water 1.00 Deionized water 14.81 Organic phase Butyl glycol 7.00 Pluriol E300 from BASF SE 2.80 Aluminum pigment available from Altana-Eckart (Alu Stapa Hydrolux 5.00 8154)
2.2 Preparation of an Inventive Waterborne Basecoat Material A2 Based on an Inventive Multistage Polymer of Olefinically Unsaturated Compounds

(28) The components listed under aqueous phase in table 2.2 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 90-95 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(29) TABLE-US-00009 TABLE 2.2 Aqueous basecoat material A2 (inventive) Component Parts by weight Aqueous phase 3% strength NaMg phyllosilicate solution 10.00 Deionized water 16.33 n-Butoxypropanol 3.20 Polyurethane-modified polyacrylate prepared as per page 7, line 55 3.60 to page 8, line 23 of DE 4437535 A1 Polyester prepared as per example D, column 16, lines 37-59 of DE 2.70 40 09 858 A1 Seed-core-shell acrylate BM2 26.05 Melamine-formaldehyde resin (Cymel 303 from Allnex) 3.20 10% strength dimethylethanolamine in water 1.80 30 wt % strength aqueous Rheovis AS 1130 solution, available from 2.00 BASF SE Deionized water 16.32 Organic phase Butyl glycol 7.00 Pluriol E300 from BASF SE 2.80 Aluminum pigment available from Altana-Eckart (Alu Stapa Hydrolux 5.00 8154)
2.3 Preparation of an Inventive Waterborne Basecoat Material A3 Based on an Inventive Multistage Polymer of Olefinically Unsaturated Compounds

(30) The aqueous basecoat material A3 is prepared in the same way as for table 2.2, using, rather than the inventive seed-core-shell acrylate BM2, the inventive seed-core-shell acrylate BM3, which has an identical solids content and solvent content.

(31) 2.4 Preparation of Noninventive Waterborne Basecoat Materials A4 to A7 Based on Noninventive Multistage Polymers of Olefinically Unsaturated Compounds

(32) Waterborne basecoat materials A4 to A7 are prepared in the same way as for table 2.2, using, instead of the inventive seed-core-shell acrylate BM2, the noninventive seed-core-shell acrylates BM4, BM5, BM6 and BM7, respectively.

(33) TABLE-US-00010 TABLE 2.3 Compositions of waterborne basecoat materials A1 to A7 WBM Binder Inventive Noninventive A1 Polyurethane resin prepared as per X international patent application WO 92/15405, page 15, lines 23-28 A2 Seed-core-shell acrylate BM2 X A3 Seed-core-shell acrylate BM3 X A4 Seed-core-shell acrylate BM4 X A5 Seed-core-shell acrylate BM5 X A6 Seed-core-shell acrylate BM6 X A7 Seed-core-shell acrylate BM7 X
Comparison between Waterborne Basecoat Materials A1, A2 and A3, and A4 to A7

(34) For the purpose of determining the adhesion properties, multicoat paint systems were produced according to the following general procedure:

(35) Original Finishes

(36) Atop a precoated metallic substrate with dimensions of 1020 cm, the waterborne basecoat material is applied by means of dual application; in the first step, application takes place electrostatically with a target film thickness of 10-12 m, and in the second step, after a 3-minute flashing time at room temperature, pneumatically with a target film thickness of 4-6 m. The resulting waterborne basecoat film is subsequently dried, after a further flashing time of 5 minutes at room temperature, in a forced air oven at 80 C. for 10 minutes. Applied over the dried waterborne basecoat film is a commercial two-component clearcoat material (Evergloss from BASF Coatings GmbH), with a target film thickness of 40-45 m. The resulting clearcoat film is flashed at room temperature for 20 minutes, followed by curing in a forced air oven at 140 C. for 20 minutes more. The system obtainable in this way is referred to below as original finish.

(37) Alternatively, curing of the basecoat and clearcoat films is carried out at 30 minutes/160 C. (referred to hereinafter as overbaked original finish) or 20 minutes/125 C. (referred to below as underbaked original finish).

(38) Refinishes

(39) Over the original finish or alternatively over an overbaked or underbaked original finish, the waterborne basecoat material is again applied by dual application, with application in the first step taking place electrostatically (target film thickness of 10-12 m) and in the second step, after a 3-minute flashing time at room temperature, pneumatically (target film thickness of 4-6 m). The resulting waterborne basecoat film, after a further 5-minute flashing time at room temperature, is subsequently dried in a forced air oven at 80 C. for 10 minutes. Over this dried waterborne basecoat film, a commercial two-component clearcoat material (Evergloss from BASF Coatings GmbH) is applied, with a target film thickness of 40-45 m. The resulting clearcoat film is flashed at room temperature for 20 minutes; this is followed by curing in a forced air oven at 140 C. for 20 minutes more. The system obtainable accordingly is referred to below as refinish.

(40) Alternatively, curing of the basecoat and clearcoat films is carried out at 30 minutes/160 C. (referred to hereinafter as overbaked refinish) or 20 minutes/125 C. (referred to below as underbaked refinish).

(41) Also produced is a further refinish system, by the application, to an original finish abraded with an abrasive paper, of a commercial two-component refinish clearcoat material (kratzfest from BASF Coatings GmbH). The resulting clearcoat film is flashed at room temperature for 20 minutes; this is followed by curing in a forced air oven at 80 C. for 20 minutes more. This system is referred to below as 80 C. refinish system.

(42) The refinishes were carried out on the one hand independently of the waterborne basecoat material of the original finish with A1 as reference, and on the other hand with the respectively corresponding waterborne basecoat materials also used for the original finish.

(43) Table 2.4 summarizes the differences of the individual multicoat paint systems in relation to the baking conditions of the clearcoat.

(44) TABLE-US-00011 TABLE 2.4 Overview of multicoat systems a1 to a7 System Original finishes Refinishes a2 a3 a5 a6 a1 (over- (under- a4 (over- (under- a7 (normal) baked) baked) (normal) baked) baked) (80 C.) Clearcoat 20 min./ 30 min./ 20 min./ 20 min./ 20 min./ 20 min./ 20 min./ drying 140 C. 160 C. 125 C. 140 C. 140 C. 140 C. 140 C. (original finish) Clearcoat 20 min./ 30 min./ 20 min./ 20 min./ drying 140 C. 160 C. 125 C. 80 C. (refinish)

(45) The technological properties of the multicoat systems were assessed by implementing cross-cuts according to DIN EN ISO 2409 (rating GT 0 to GT 5; 0=best score; 5=worst score). The corresponding investigations were performed on unexposed samples and also following exposure to condensation water. For this purpose, steel panels with the respective multicoat systems were stored over a period of 10 days in a climate chamber under CH test conditions according to DIN EN ISO 6270-2:2005-09. The panels were subsequently inspected for blistering and swelling, 24 hours after removal from the climate chamber.

(46) The incidence of blisters was assessed as follows by a combination of two values: The number of blisters was evaluated by a quantity figure from 1 to 5, with m1 denoting very few and m5 very many blisters. The size of the blisters was evaluated by a size report, likewise from 1 to 5, with g1 denoting very small and g5 very large blisters.

(47) The designation m0g0, accordingly, denotes a blister-free finish after condensation water storage, and represents a satisfactory result in terms of blistering.

(48) In addition, the multicoat paint systems were investigated for stone-chip adhesion. For this purpose, the stone-chip test according to DIN EN ISO 20567-1, method B was carried out. The resulting pattern of damage was likewise assessed in accordance with DIN EN ISO 20567-1.

(49) Tables 2.5 to 2.8 and tables 2.9 to 2.11 summarize the results of the various tests relating to stone-chip resistance and relating, respectively, to the cross-cut before and after condensation water testing.

(50) TABLE-US-00012 TABLE 2.5 Stone-chip resistance of original finishes a1 to a3 of waterborne basecoat materials A1 to A7 Stone-chip results Waterborne basecoat materials A1 to A7 A1 A2 A3 A4 A5 A6 A7 a1 2.5 2 2 3.5 3 2.5 3.5 a2 2 1.5 2 2 2.5 2.5 3 a3 2 2 2 2.5 3 2 4

(51) TABLE-US-00013 TABLE 2.6 Stone-chip resistance of refinishes a4 to a6 of waterborne basecoat materials A1 to A7 in the original finish and A1 in the refinish Stone-chip outcomes Waterborne basecoat materials A1 to A7 Basecoat original finish A1 A2 A3 A4 A5 A6 A7 Basecoat refinish A1 A1 A1 A1 A1 A1 A1 a4 1.5 2 1.5 2.5 4 4 5 a5 1.5 1.5 2 3 4.5 3 5 a6 2 1.5 1.5 2.5 4 3 4

(52) TABLE-US-00014 TABLE 2.7 Stone-chip resistance of refinishes a4 to a6 of waterborne basecoat materials A1 to A7 in the original finish and A1 in the refinish, with sample plate conditioning at 20 C. in deviation from DIN EN ISO 20567-1 Stone-chip results Waterborne basecoat materials A1 to A7 Basecoat original finish A1 A2 A3 A4 A5 A6 A7 Basecoat refinish A1 A1 A1 A1 A1 A1 A1 a4 1.5 1.5 1.5 3 4 4 4 a5 1.5 1.5 1.5 3.5 5 4 5 a6 1.5 1.5 1.5 3 4 4 4

(53) TABLE-US-00015 TABLE 2.8 Stone-chip resistance of refinishes a4 to a6 of waterborne basecoat materials A1, A2, A5, and A7 Stone-chip outcomes Waterborne basecoat materials A1, A2, A5, and A7 Basecoat A1 A2 A5 A7 original finish Basecoat A1 A2 A5 A7 refinish a4 1.5 2 5 4 a5 1.5 2 5 3 a6 2 1.5 5 3.5

(54) The results illustrate that only the use of the inventive multistage polymers of olefinically unsaturated compounds exhibits advantages in relation to stone-chip resistance relative to the prior art, whereas the noninventive multistage polymers display significant weaknesses, especially in the refinish coatings.

(55) TABLE-US-00016 TABLE 2.9 Cross-cut resistance of original finishes a2 and a3 of waterborne basecoat materials A1, A2, A5, and A7 Cross-cut outcomes Waterborne basecoat materials A1, A2, A5, and A7 A1 A2 A5 A7 a2 GT 0 GT 0 GT 0 GT 0 a3 GT 0 GT 0 GT 0.5 GT 0.5

(56) TABLE-US-00017 TABLE 2.10 Cross-cut resistance of refinishes a4 to a6 of waterborne basecoat materials A1, A2, A5, and A7 Cross-cut outcomes Waterborne basecoat materials A1, A2, A5, and A7 Basecoat original A1 A2 A5 A7 finish Basecoat refinish A1 A2 A5 A7 a4 GT 0 GT 0 GT 0 GT 0 a5 GT 0 GT 0 GT 0.5 GT 0 a6 GT 0 GT 0 GT 0 GT 0

(57) TABLE-US-00018 TABLE 2.11 Cross-cut resistance/blistering and swelling after condensation water exposure of multicoat systems a1 and a7 of waterborne basecoat materials A1, A2, A5, and A7 Cross-cut outcomes/results of condensation water test Waterborne basecoat materials A1, A2, A5, and A7 Basecoat A1 A2 A5 A7 original finish Basecoat A1 A2 A5 A7 refinish a1 GT 0 GT 0 GT 0 GT 0 m0g0/ m0g0/ GT 0/slight GT 0/slight swelling no swelling swelling swelling a7 GT 0 GT 0 GT 4 GT 5 Assessment nOK OK nOK nOK Key to blistering: m = number of blisters g = size of blisters OK = satisfactory result nOK = unsatisfactory result

(58) In the DIN EN ISO 2409 cross-cut tests, the inventive multicoat paint system A2 in all constructions achieved the GT 0 rating, while the waterborne basecoat materials based on the noninventive multistage polymers display significant weaknesses in the 80 C. refinish construction. Furthermore, by using the inventive seed-core-shell acrylate BM2, it is possible to achieve significant improvements in the swelling behavior of the reference sample A1 based on the prior art.

(59) 2.5 Preparation of a Noninventive Waterborne Basecoat Material B1 Based on a Noninventive Multistage Acrylate as Per Korea Polym. J., Vol. 7, No. 4, pp. 213-222

(60) The components listed under aqueous phase in table 2.12 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 95-100 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(61) TABLE-US-00019 TABLE 2.12 Waterborne basecoat material B1 (not inventive) Component Parts by weight Aqueous phase Multistage acrylate BM8 (not inventive) 55 Deionized water 29 3 wt % strength aqueous Rheovis 2.5 AS 1130 solution; rheological agent, available from BASF, in water 10% strength dimethylethanolamine in water 1 Organic phase Butyl glycol 5.5 Aluminum pigment available from Altana-Eckart 7 (Alu Stapa Hydrolux 8154)
2.6 Preparation of an Inventive Waterborne Basecoat Material B2 Based on an Inventive Seed-core-shell Acrylate

(62) The components listed under aqueous phase in table 2.13 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 70-75 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(63) TABLE-US-00020 TABLE 2.13 Waterborne basecoat material B2 (inventive) Component Parts by weight Aqueous phase Seed-core-shell acrylate BM2 50 Deionized water 34 3 wt % strength aqueous Rheovis 2.5 AS 1130 solution; rheological agent, available from BASF, in water 10% strength dimethylethanolamine in water 1 Organic phase Butyl glycol 5.5 Aluminum pigment available from Altana-Eckart 7 (Alu Stapa Hydrolux 8154)
Comparison between Waterborne Basecoat Materials B1 and B2

(64) The amount of deionized water needed to adjust the spray viscosity for waterborne basecoat materials B1 and B2, and the resulting solids content of each of the formulations, are summarized in table 2.14.

(65) TABLE-US-00021 TABLE 2.14 Amount of water to adjust the spray viscosity, and resulting solids content, of basecoat materials B1 and B2 B1 B2 Addition of water [%] 80 12 Spray viscosity [mPa .Math. s]; 95-100 70-75 measured at 1000 s.sup.1 Solids content [%] 10 16

(66) The results demonstrate that the use of the noninventive binder BM8 results in a solids contentowing to the large amount of deionized water needed to set a spray viscosity obvious for the skilled personwhich is no longer acceptable for application in modern multicoat paint systems as are employed in the automobile industry.

(67) In order to determine the stability with respect to incidence of blisters after condensation water storage, multicoat paint systems were produced in accordance with the following general procedure:

(68) Atop a precoated steel panel with dimensions of 1020 cm, the waterborne basecoat material was applied pneumatically. The resulting waterborne basecoat film was flashed at room temperature for 10 minutes and then dried in a forced air oven at 80 C. for 10 minutes. Over the dried waterborne basecoat film, a commercial two-component refinished clearcoat (2 K Reparatur-Klarlack, kratzfest, from BASF Coatings GmbH) was applied. The resulting clearcoat film was flashed at room temperature for 20 minutes, followed by curing in a forced air oven at 80 C. for 20 minutes more.

(69) The steel panels obtained accordingly were then stored over a period of 10 days in a climate chamber under CH test conditions according to DIN EN ISO 6270-2:2005-09. The panels were subsequently, 24 hours following removal from the climate chamber, examined in relation to blistering.

(70) The incidence of blisters was assessed as follows by a combination of two values: The number of blisters was evaluated by a quantity figure from 1 to 5, with m1 denoting very few and m5 very many blisters. The size of the blisters was evaluated by a size report, likewise from 1 to 5, with g1 denoting very small and g5 very large blisters. The designation m0g0, accordingly, denotes a blister-free finish after condensation water storage, and represents a satisfactory result in terms of blistering.

(71) TABLE-US-00022 TABLE 2.15 Blistering after condensation water exposure of waterborne basecoat materials B1 and B2 B1 B2 Blistering m3/g1 m0/g0 Assessment nOK OK Key: m = number of blisters g = size of blisters OK = satisfactory outcome nOK = unsatisfactory outcome

(72) The results show that when the inventive seed-core-shell polyacrylate BM2 is used, in contrast to the binder BM8 described in the literature, blisters no longer appear after condensed water exposure.

(73) 2.7 Preparation of the Noninventive Waterborne Basecoat Materials C1 to C3 Based on a Noninventive Multistage Acrylate as Per Korea Polym. J., Vol. 7, No. 4, pp. 213-222

(74) The components listed under aqueous phase in table 2.16 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 905 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(75) TABLE-US-00023 TABLE 2.16 Waterborne basecoat materials C1 to C3 (not inventive) Parts by weight Component C1 C2 C3 Aqueous phase 3% strength NaMg-phyllosilicate 10 0 0 solution Multistage acrylate BM8 (not inventive) 28.4 28.4 28.4 Deionized water 30.3 39.3 34.8 Polyester prepared as per example D, 2.7 2.7 2.7 column 16, lines 37-59 of DE 40 09 858 A1 n-Butoxypropanol 3.2 3.2 3.2 Melamine-formaldehyde resin (Cymel 3.2 3.2 3.2 303 from Allnex) 10% strength dimethylethanolamine in 2.3 2.3 2.3 water Polyurethane-modified polyacrylate, 3.6 3.6 3.6 prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 3 wt % strength aqueous Rheovis AS 1.5 2.5 1 1130 solution (Rheovis AS 1130 available from BASF SE) Aquatix 8421, available from BYK- 0 0 2 Chemie GmbH Aquacer 526, available from BYK- 0 0 3 Chemie GmbH 50 wt % strength solution of Rheovis 0 0 1 PU1250 in butyl glycol (Rheovis PU1250 available from BASF SE) Organic phase Butyl glycol 7.0 7.0 7.0 Pluriol E300 from BASF SE 2.8 2.8 2.8 Aluminum pigment available from 5.0 5.0 5.0 Altana-Eckart (Alu Stapa Hydrolux 8154)
2.8 Preparation of the Inventive Waterborne Basecoat Materials C4 to C6 Based on an Inventive Seed-core-shell Acrylate

(76) The components listed under aqueous phase in table 2.17 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 905 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(77) TABLE-US-00024 TABLE 2.17 Waterborne basecoat materials C4 to C6 (inventive) Parts by weight Component C4 C5 C6 Aqueous phase 3% strength NaMg-phyllosilicate 10 0 0 solution Seed-core-shell acrylate BM2 25.95 25.95 25.95 Deionized water 32.75 41.75 37.25 Polyester prepared as per example D, 2.7 2.7 2.7 column 16, lines 37-59 of DE 40 09 858 A1 n-Butoxypropanol 3.2 3.2 3.2 Melamine-formaldehyde resin (Cymel 3.2 3.2 3.2 303 from Allnex) 10% strength dimethylethanolamine in 2.3 2.3 2.3 water Polyurethane-modified polyacrylate, 3.6 3.6 3.6 prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 3 wt % strength aqueous Rheovis AS 1.5 2.5 1 1130 solution (Rheovis AS 1130 available from BASF SE) Aquatix 8421, available from BYK- 0 0 2 Chemie GmbH Aquacer 526, available from BYK- 0 0 3 Chemie GmbH 50 wt % strength solution of Rheovis 0 0 1 PU1250 in butyl glycol (Rheovis PU1250 available from BASF SE) Organic phase Butyl glycol 7.0 7.0 7.0 Pluriol E300 from BASF SE 2.8 2.8 2.8 Aluminum pigment available from 5.0 5.0 5.0 Altana-Eckart (Alu Stapa Hydrolux 8154)
Comparison between Waterborne Basecoat Materials C1 to C3, and C4 to C6

(78) For the purpose of determining the stability toward incidence of blisters and swelling after condensation water storage, and also for determining the adhesion properties before and after condensation water storage, multicoat paint systems were produced according to the following general procedure:

(79) Original Finishes

(80) Atop a precoated metallic substrate with dimensions of 1020 cm, the waterborne basecoat material is applied by means of dual application; in the first step, application takes place electrostatically with a target film thickness of 8-9 m, and in the second step, after a 2-minute flashing time at room temperature, pneumatically with a target film thickness of 4-5 m. The resulting waterborne basecoat film is subsequently dried, after a further flashing time of 5 minutes at room temperature, in a forced air oven at 80 C. for 5 minutes. Applied over the dried waterborne basecoat film is a commercial two-component clearcoat material (ProGloss from BASF Coatings GmbH), with a target film thickness of 40-45 m. The resulting clearcoat film is flashed at room temperature for 10 minutes, followed by curing in a forced air oven at 140 C. for 20 minutes more. The system obtainable in this way is referred to below as original finish.

(81) Alternatively, curing of the basecoat and clearcoat films is carried out at 60 minutes/140 C. (referred to hereinafter as overbaked original finish).

(82) Refinishes

(83) Over the original finish or alternatively over the overbaked original finish, the waterborne basecoat material is again applied by dual application, with application in the first step taking place electrostatically (target film thickness of 8-9 m) and in the second step, after a 2-minute flashing time at room temperature, pneumatically (target film thickness of 4-5 m). The resulting waterborne basecoat film, after a further 5-minute flashing time at room temperature, is subsequently dried in a forced air oven at 80 C. for 10 minutes. Over this dried waterborne basecoat film, a commercial two-component clearcoat material (ProGloss from BASF Coatings GmbH) is applied, with a target film thickness of 40-45 m. The resulting clearcoat film is flashed at room temperature for 10 minutes; this is followed by curing in a forced air oven at 140 C. for 20 minutes more. The system obtainable accordingly is referred to below as refinish.

(84) Table 2.18 summarizes the differences of the individual multicoat paint systems in relation to the baking conditions of the clearcoat.

(85) TABLE-US-00025 TABLE 2.18 Overview of multicoat systems c1 to c3 System Refinishes Original finishes c2 c3 c1 (normal) (overbaked) Clearcoat drying 20 min./ 20 min./ 60 min./ (original finish) 140 C. 140 C. 140 C. Clearcoat drying 20 min./ 20 min./ (refinish) 140 C. 140 C.

(86) The technological properties of the multicoat systems were assessed by implementing cross-cuts according to DIN EN ISO 2409 (rating GT 0 to GT 5; 0=best score; 5=worst score). The corresponding investigations were performed on unexposed samples and also following exposure to condensation water. For this purpose, steel panels with the respective multicoat systems were stored over a period of 10 days in a climate chamber under CH test conditions according to DIN EN ISO 6270-2:2005-09. The panels were subsequently inspected for blistering and swelling, 24 hours after removal from the climate chamber, and the adhesion properties were tested by means of cross-cut.

(87) The incidence of blisters was assessed as follows by a combination of two values: The number of blisters was evaluated by a quantity figure from 1 to 5, with m1 denoting very few and m5 very many blisters. The size of the blisters was evaluated by a size report, likewise from 1 to 5, with g1 denoting very small and g5 very large blisters.

(88) The designation m0g0, accordingly, denotes a blister-free finish after condensation water storage, and represents a satisfactory result in terms of blistering.

(89) Tables 2.19 and 2.20 summarize the results of the various tests on blistering and swelling and also on the cross-cut before and after condensation water testing.

(90) TABLE-US-00026 TABLE 2.19 Blistering and swelling after condensation water exposure of multicoat system c1 of waterborne basecoat materials C1 to C6 Results of condensation water testing Waterborne basecoat materials C1 to C6 C1 C2 C3 C4 C5 C6 c1 m1/g1 m0/g0 m1/g3 m0/g0 m0/g0 m0/g0 Swelling yes no no no no no Assessment nOK OK nOK OK OK OK Key to blistering: m = number of blisters g = size of blisters OK = satisfactory outcome nOK = unsatisfactory outcome

(91) TABLE-US-00027 TABLE 2.20 Cross-cut resistance of multicoat systems c1 to c3 of waterborne basecoat materials C1 to C6 Cross-cut results Waterborne basecoat materials C1 to 06 C1 C2 C3 C4 C5 C6 c1 Before condensation GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 water exposure After condensation GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 water exposure c2 Before condensation GT 1 GT 0 GT 3 GT 0 GT 0 GT 0 water exposure After condensation GT 2 GT 0 GT 3 GT 0 GT 0 GT 0 water exposure c3 Before condensation GT 4 GT 3 GT 4 GT 0 GT 0 GT 0 water exposure After condensation GT 1 GT 1 GT 4 GT 0 GT 0 GT 0 water exposure

(92) The results confirm that when the inventive seed-core-shell acrylate BM2 is used (waterborne basecoat materials C4 to C6) there are no longer any problems in terms of condensation water resistance and/or adhesion; waterborne basecoat materials C1 to C3, which contain the noninventive seed-core-shell acrylate BM8 prepared as per Korea Polym. J., vol. 7, no. 4, pp. 213-222, in contrast, exhibit blistering in some cases, and weaknesses in terms of cross-cut, particularly affecting the refinish on an overbaked original finish.

(93) 2.9 Preparation of a Noninventive Waterborne Basecoat Material D1 Based on a Polyurethane Resin

(94) The components listed under aqueous phase in table 2.21 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture. This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 90-95 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(95) TABLE-US-00028 TABLE 2.21 Waterborne basecoat material D1 (not inventive) Parts by Component weight Aqueous phase 3% strength NaMg phyllosilicate 24.35 solution Deionized water 18.9 n-Butoxypropanol 1.65 2-Ethylhexanol 2.5 Polyurethane resin, prepared as per 21.25 international patent application WO 92/15405, page 15, lines 23-28 Polyester prepared as per example D, 2.6 column 16, lines 37-59, of DE 40 09 858 A1 3 wt % strength aqueous Rheovis 0.65 AS 1130 solution (Rheovis AS 1130 available from BASF SE) Melamine-formaldehyde resin (Resimene 3.8 HM 2608 from Ineos) 10% strength dimethylethanolamine in water 1.1 Pluriol P900 from BASF SE 1 Byketol-WS from Altana/BYK-Chemie GmbH 1 Polyurethane-modified polyacrylate prepared 3.8 as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 Isobutanol 2.4 1-Propoxy-2-propanol 2.2 50 wt % strength solution of Rheovis 0.8 PU1250 in butyl glycol (Rheovis PU1250 available from BASF SE) Organic phase Butyl glycol 5.6 Mixture of two commercial aluminum 4.5 pigments, available from Altana-Eckart (Alu Stapa Hydrolux 2154 & VP56450) Polyester prepared as per example D, 1.9 column 16, lines 37-59, of DE 40 09 858 A1
2.10 Preparation of an Inventive Waterborne Basecoat Material D2 Based on an Inventive Multistage Polymer of Olefinically Unsaturated Compounds

(96) The components listed under aqueous phase in table 2.22 are stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture is prepared from the components listed under organic phase. The organic mixture is added to the aqueous mixture.

(97) This is followed by stirring for 10 minutes, and a pH of 8 and a spray viscosity of 90-95 mPa.Math.s under a shearing load of 1000 s.sup.1, measured using a rotary viscometer (Rheolab QC instrument with C-LTD80/QC heating system, from Anton Paar) at 23 C., are set using deionized water and dimethylethanolamine.

(98) TABLE-US-00029 TABLE 2.22 Waterborne basecoat material D2 (inventive) Parts by Component weight Aqueous phase 3% strength NaMg phyllosilicate 26 solution Deionized water 14.15 n-Butoxypropanol 1.65 2-Ethylhexanol 2.5 Seed-core-shell acrylate BM2 (inventive) 21.25 Polyester prepared as per example D, 2.6 column 16, lines 37-59, of DE 40 09 858 A1 3 wt % strength aqueous Rheovis AS 0.65 1130 solution (Rheovis AS 1130 available from BASF SE) Melamine-formaldehyde resin (Resimene 3.8 HM 2608 from Ineos) 10% strength dimethylethanolamine in water 1.1 Pluriol P900 from BASF SE 1 Byketol-WS from Altana/BYK-Chemie GmbH 1 Polyurethane-modified polyacrylate prepared 3.8 as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 Isobutanol 2.4 1-Propoxy-2-propanol 2.2 50 wt % strength solution of Rheovis 0.8 PU1250 in butyl glycol (Rheovis PU1250 available from BASF SE) Organic phase Butyl glycol 5.6 Mixture of two commercial aluminum pigments, 4.5 available from Altana-Eckart (Alu Stapa Hydrolux 2154 & VP56450) Polyester prepared as per example D, 1.9 column 16, lines 37-59, of DE 40 09 858 A1
Comparison between Waterborne Basecoat Materials D1 and D2

(99) To determine the angle-dependent brightnesses that result from the different waterborne basecoat materials and that in turn result in the flop effect, multicoat paint systems were produced in accordance with the following general procedure:

(100) A precoated steel panel with dimensions of 1020 cm was coated with a standard primer-surfacer (SecuBloc from BASF Coatings GmbH) in a target film thickness of 25-35 m. After flashing at room temperature for 5-10 minutes and intermediate drying of the aqueous primer-surfacer over a period of 10 minutes at 70 C., it was baked at a temperature of 150 C. over a period of 10 minutes.

(101) Waterborne basecoat materials D1 and D2 were applied to thus-coated steel panels by means of dual application; application in the first step took place electrostatically with a target film thickness of 8-11 m, while application in the second step took place pneumatically, after a flashing time of 3 minutes and 40 seconds at room temperature, with a target film thickness of 3-5 m. The resulting waterborne basecoat film, after a further flashing time at room temperature of 4 minutes and 30 seconds, was then dried in a forced air oven at 70 C. for 5 minutes. Atop the dried waterborne basecoat film, a scratch-resistant two-component clearcoat (iGloss from BASF Coatings GmbH) was applied with a target film thickness of 40-45 m. The resulting clearcoat film was flashed at room temperature for 7 minutes, followed by curing in a forced air oven at 140 C. for 22 minutes more.

(102) The multicoat paint systems obtained by this procedure were subjected to measurement using a spectrophotometer from X-Rite (X-Rite MA68 Multi-Angle Spectrophotometer). During this measurement, the surface is illuminated with a light source. At different angles, spectral detection in the visible range is carried out. The spectral measurement values obtained in this way can be used, with incorporation of the standard spectral values and of the reflection spectrum of the light source used, to calculate color values in the CIEL*a*b* color space, where L* characterizes the lightness, a* the red-green value, and b* the yellow-blue value. This method is described for materials comprising metal flake in ASTM E2194-12. The derived value which is often employed to quantify the metallic effect is the so-called flop index; it describes primarily the relationship between lightness and observation angle (see A. B. J. Rodriguez, JOCCA, 1992 (4), pp. 150-153). The flop index (FL) can be calculated from the lightness values found for the viewing angles of 15, 45 and 110, in accordance with the formula
FL=2.69(L*.sub.15L*.sub.110).sup.1.11/(L*.sub.45).sup.0.86.

(103) TABLE-US-00030 TABLE 2.23 Flop indices of waterborne basecoat materials D1 and D2 Waterborne basecoat Flop material Inventive Index D1 no 13.4 D2 yes 14.4

(104) The metallic flop was very highly pronounced for both multicoat paint systems, with the inventive waterborne basecoat material, based on the inventive seed-core-shell acrylate, showing advantages.

(105) To determine the popping and running tendency of the waterborne basecoat materials D1 and D2, multicoat paint systems were produced in accordance with DIN EN ISO 28199-1 and DIN EN ISO 28199-3, by the following general procedure:

(106) A precoated perforated metal panel with dimensions of 5720 cm (as per DIN EN ISO 28199-1 section 8.1 version A) was coated with a standard primer-surfacer (SecuBloc from BASF Coatings GmbH) in a target film thickness of 25-35 m. After flashing at room temperature for 5-10 minutes and intermediate drying of the aqueous primer-surfacer over a period of 10 minutes at 70 C., it was baked at a temperature of 150 C. over a period of 10 minutes.

(107) In analogy to DIN EN ISO 28199-1 section 8.2, steel panels thus coated were prepared, and subsequently the waterborne basecoat materials D1 and D2 were applied to them electrostatically in the form of a wedge, with a film thickness of 0 m to at least 30 m. The resulting waterborne basecoat film, after a flashing time at room temperature of 4 minutes and 30 seconds, was dried in a forced air oven at 70 C. for 5 minutes. In the case of the test for runs, the panels were flashed and dried in a vertically standing position. Applied atop the dried waterborne basecoat film was a scratch-resistant two-component clearcoat (iGloss from BASF Coatings GmbH) with a target film thickness of 40-45 m. The resulting clearcoat film was flashed at room temperature for 7 minutes, followed by curing in a forced air oven at 140 C. for 22 minutes more.

(108) The popping limitthat is, the basecoat film thickness above which pops (popping marks) appearwas determined in accordance with DIN EN ISO 28199-3 section 5.

(109) The running tendency was determined in accordance with DIN EN ISO 28199-3 section 4. As well as the film thickness at which a run exceeds the length of 10 mm from the bottom edge of the perforation, a determination was made of the film thickness above which an initial tendency to run can be observed visually at a perforation.

(110) The respective film thicknesses were determined in accordance with DIN EN ISO 2808 method 12A (e.g., with the MiniTest 3100-4100 measuring instrument from ElektroPhysik). The corresponding experimental results are found in table 2.24.

(111) TABLE-US-00031 TABLE 2.24 Popping and running tendency of waterborne basecoat materials D1 and D2 (basecoat wedge from 0 to about 50 m) D1 (Reference) D2 (inventive) Runs (>0 mm) 19 m none Runs (>10 mm) 46 m none Pops 18 m none

(112) The results compiled in table 2.24 show that using the inventive binder BM2 it is possible to achieve a significantly more robust basecoat formulation, exhibiting significant advantages in terms of runs and popping tendency by comparison with the reference.

(113) To determine the storage stability of the waterborne basecoat materials D1 and D2, both materials were investigated, before and after storage at 40 C. for 2 weeks, with a rotary viscometer conforming to DIN 53019-1 and calibrated to DIN 53019-2, under temperature-controlled conditions (23.0 C.0.2 C.). In this investigation, the samples were subjected to shearing first for 5 minutes at a rate of 1000 s.sup.1 (loading phase) and then for 8 minutes at a rate of 1 s.sup.1 (unloading phase). The average viscosity level during the loading phase (high-shear viscosity) and also the level after 8 minutes of unloading phase (low-shear viscosity) were determined from the measurement data, and the values before and after storage were compared with one another.

(114) The percentage changes in the high-shear and low-shear viscosities after storage at 40 C. are summarized in table 1.25.

(115) TABLE-US-00032 TABLE 2.25 Storage stability of the waterborne basecoat materials in the form of viscosity changes after 2 weeks of storage at 40 C. D1 (Reference) D2 (Inventive) Change in high-shear 22.3% 6.0% viscosity at 1000 s.sup.1 Change in low-shear 15.1% 6.2% viscosity at 1 s.sup.1

(116) Waterborne basecoat material D2, comprising the inventive binder BM2, exhibits a significantly more stable high-shear and low-shear viscosity after storage at 40 C. than the reference D1.

(117) For the purpose of determining the adhesion properties, multicoat paint systems were produced according to the following general procedure:

(118) Original Finishes

(119) A precoated metallic substrate with dimensions of 1020 cm was coated with a standard primer-surfacer (SecuBloc from BASF Coatings GmbH) in a target film thickness of 25-35 m. After flashing at room temperature for 5-10 minutes and intermediate drying of the aqueous primer-surfacer over a period of 10 minutes at 70 C., it was baked at a temperature of 150 C. over a period of 10 minutes.

(120) Waterborne basecoat materials D1 and D2 were applied to thus-coated steel panels by means of dual application; application in the first step took place electrostatically with a target film thickness of 8-11 m, while application in the second step took place pneumatically, after a flashing time of 3 minutes and 40 seconds at room temperature, with a target film thickness of 3-5 m. The resulting waterborne basecoat film, after a further flashing time at room temperature of 4 minutes and 30 seconds, was then dried in a forced air oven at 70 C. for 5 minutes. Atop the dried waterborne basecoat film, a scratch-resistant two-component clearcoat (iGloss from BASF Coatings GmbH) was applied with a target film thickness of 40-45 m. The resulting clearcoat film was flashed at room temperature for 7 minutes, followed by curing in a forced air oven at 140 C. for 22 minutes more. The system obtainable in this way is referred to below as original finish.

(121) Alternatively, curing of the basecoat film and clearcoat film was carried out at 60 minutes/145 C. (referred to below as overbaked original finish).

(122) Refinishes

(123) For the refinishes, the original finishes or, alternatively, the overbaked original finishes either were used without being abraded, or were abraded matt or partially (two back-and-forth strokes) using a hard rubber sanding block with dimensions of 1157025 mm and P 500 grade abrasive paper.

(124) Waterborne basecoat materials D1 and D2 were applied to the substrates thus treated or untreated, again by means of dual application, with application taking place in the first step electrostatically (target film thickness of 8-11 m) and in the second step, after a flashing time of 3 minutes and 40 seconds at room temperature, pneumatically (target film thickness of 3-5 m). Subsequently, after a further flashing time of 4 minutes and 30 seconds at room temperature, the resulting waterborne basecoat film was dried in a forced air oven at 70 C. for 5 minutes. Applied atop the dried waterborne basecoat film was a scratch-resistant two-component clearcoat (iGloss from BASF Coatings GmbH) with a target film thickness of 40-45 m. The resulting clearcoat film was flashed at room temperature for 7 minutes, followed by curing in a forced air oven at 140 C. for 22 minutes more. The system obtainable in this way is referred to below as refinish.

(125) Alternatively, a two-component refinish clearcoat (2K Reparatur-Klarlack from BASF Coatings GmbH) was applied with a target film thickness of 40-45 m. The resulting clearcoat film was flashed at room temperature for 7 minutes, followed by curing in a forced air oven at 85 C. for 37 minutes more. This system is referred to below as 85 C. refinish system.

(126) Table 2.26 summarizes the differences in the individual multicoat systems in relation to the baking conditions of the clearcoat and also to the surface treatment of the clearcoat in the original finish.

(127) TABLE-US-00033 TABLE 2.26 Overview of multicoat systems d1 to d10 System Original finish Refinishes d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 (normal) (normal) (overbaked) 85 C. refinish Clearcoat 22 min./ 22 min./ 60 min./ 22 min./ drying 140 C. 140 C. 145 C. 140 C. (original finish) Abrading a) a) b) c) a) b) c) a) b) c) Clearcoat 22 min./ 37 min./ drying 140 C. 85 C. (refinish) a)Clearcoat in original finish is not abraded b)Clearcoat in original finish is partially abraded (2 back-and-forth strokes) c)Clearcoat in original finish is abraded matt

(128) In order to assess the condensation water resistance, the multicoat systems dl to d10 of waterborne basecoat materials D1 and D2 were stored over a period of 10 days in a climate chamber under CH test conditions according to DIN EN ISO 6270-2:2005-09. One hour and also 24 hours following removal from the climate chamber, the panels were subsequently investigated visually in respect of blistering and also in relation to the adhesion properties.

(129) The incidence of blisters was assessed as follows by a combination of two values: The number of blisters was evaluated by a quantity figure from 1 to 5, with m1 denoting very few and m5 very many blisters. The size of the blisters was evaluated by a size report, again from 1 to 5, with g1 denoting very small and g5 very large blisters.

(130) The designation m0g0 denotes, accordingly, a blister-free coating after condensation water storage, and represents an OK result in terms of blistering.

(131) The adhesion properties of the multicoat systems were assessed first by cross-cuts in accordance with DIN EN ISO 2409 (rating GT 0 to GT 5; 0=best score; 5=worst score).

(132) Secondly, the stone-chip adhesion of waterborne basecoat materials D1 and D2 was investigated; for this purpose, the stone-chip test of DIN EN ISO 20567-1, method B was carried out. The resulting damage pattern was likewise assessed according to DIN EN ISO 20567-1.

(133) In addition, steam jet tests were carried out according to DIN 55662, method B. The scratches (in a diagonal cross) were made with a Sikkens scratch needle (see DIN EN ISO 17872 Annex A). The assessment of the steam jet test results was carried out to DIN 55662, more particularly determining the maximum detachment width in millimetres.

(134) Additionally, steam jet tests were carried out according to DIN 55662, method B (a diagonal cross is made using a Sikkens scratch needle according to DIN EN ISO 17872 appendix A) on substrates having previously undergone a stone-chip test according to DIN EN ISO 20567-1 method B. The scale utilized for the visual evaluation of the damage pattern was as follows:

(135) KW0=no change in the sample

(136) KW1=slight washout of the damage present

(137) KW2=clearly visible washout of the damage present in a coating film

(138) KW3=complete delamination of a coating film in the region of the jet

(139) KW4=complete delamination of a coating film beyond the jet region

(140) KW5=detachment of the complete coating film down to the substrate

(141) Tables 2.27 to 2.31 summarize the results of the various adhesion tests (cross-cut, stone-chip, steam jet) before and after condensation water testing.

(142) TABLE-US-00034 TABLE 2.27 Cross-cut resistance of multicoat systems d1 to d10 of waterborne basecoat materials D1 and D2 before and 1 hour after condensation water exposure Cross-cut results Waterborne basecoat materials D1 and D2 D1 D2 d1 Before condensation water exposure GT 0 GT 0 After condensation water exposure GT 0 GT 0 d2 Before condensation water exposure GT 1 GT 0 After condensation water exposure GT 0.5 GT 0 d3 Before condensation water exposure GT 0 GT 0 After condensation water exposure GT 0.5 GT 0.5 d4 Before condensation water exposure GT 0 GT 0 After condensation water exposure GT 1 GT 0 d5 Before condensation water exposure GT 2 GT 0 After condensation water exposure GT 0 GT 0 d6 Before condensation water exposure GT 0.5 GT 0 After condensation water exposure GT 0.5 GT 0 d7 Before condensation water exposure GT 0.5 GT 0 After condensation water exposure GT 0.5 GT 0 d8 Before condensation water exposure GT 0.5 GT 0 After condensation water exposure GT 0 GT 0 d9 Before condensation water exposure GT 0.5 GT 0.5 After condensation water exposure GT 0 GT 0 d10 Before condensation water exposure GT 1 GT 0.5 After condensation water exposure GT 0 GT 0

(143) The results confirm that when using the inventive seed-core-shell acrylate BM2 (waterborne basecoat material D2) there are no problems with regard to cross-cut adhesion after condensation water exposure; the evaluation of the damage pattern, made according to DIN EN ISO 2409, is better for many of the systems, but at least equally good to that in the case of the reference (D1).

(144) TABLE-US-00035 TABLE 2.28 Blistering after condensation water exposure of multicoat systems d1 to d10 of waterborne basecoat materials D1 and D2 Results of the condensation water test Waterborne basecoat materials D1 and D2 D1 D2 d1 m0/g0 m0/g0 d2 m0/g0 m0/g0 d3 m0/g0 m0/g0 d4 m0/g0 m0/g0 d5 m0/g0 m0/g0 d6 m0/g0 m0/g0 d7 m0/g0 m0/g0 d8 m0/g0 m0/g0 d9 m0/g0 m0/g0 d10 m0/g0 m0/g0 Assessment OK OK Key to blistering: m = number of blisters g = size of blisters OK = satisfactory outcome nOK = unsatisfactory outcome

(145) None of the multicoat systems showed blistering after condensation water exposure.

(146) TABLE-US-00036 TABLE 2.29 Stone-chip resistance of the multicoat systems d1 to d10 of waterborne basecoat materials D1 and D2 Stone-chip results Waterborne basecoat materials D1 and D2 D1 D2 d1 2 1 d2 4 3 d3 4 2.5 d4 4.5 2.5 d5 3.5 3 d6 4 2 d7 4 2 d8 5 2.5 d9 4 3 d10 5 3.5

(147) Use of the inventive seed-core-shell acrylate BM2 (waterborne basecoat material D2) gave a significant improvement in terms of stone-chip resistance by comparison with the reference (D1).

(148) TABLE-US-00037 TABLE 2.30 Steam jet resistance (to DIN 55662, method B) of multicoat systems d1 to d7 of waterborne basecoat materials D1 and D2 before and 1 or 24 hour(s) after condensation water exposure Steam jet results Waterborne basecoat materials D1 and D2 D1 D2 d1 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h >1 mm/nOK <1 mm/OK 24 h <1 mm/OK <1 mm/OK d2 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h >1 mm/nOK <1 mm/OK 24 h 1 mm/jOK <1 mm/OK d3 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h <1 mm/OK <1 mm/OK 24 h 1 mm/jOK <1 mm/OK d4 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h 1 mm/jOK <1 mm/OK 24 h <1 mm/OK <1 mm/OK d5 Before condensation water exposure >1 mm/nOK <1 mm/OK After condensation water exposure 1 h >1 mm/nOK <1 mm/OK 24 h >1 mm/nOK <1 mm/OK d6 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h 1 mm/jOK <1 mm/OK 24 h 1 mm/jOK <1 mm/OK d7 Before condensation water exposure <1 mm/OK <1 mm/OK After condensation water exposure 1 h 1 mm/jOK <1 mm/OK 24 h 1 mm/jOK <1 mm/OK Key to steam jet results (maximum width of detachments): <1 mm = OK (satisfactory outcome) 1 mm = jOK (just satisfactory outcome) >1 mm = nOK (unsatisfactory outcome)

(149) When the inventive seed-core-shell acrylate BM2 (waterborne basecoat material D2) is used in the steam jet test according to DIN 55662, method B, the result obtained is consistently satisfactory, whereas the reference (D1) exhibits weaknesses in numerous tests, particularly after condensation water exposure and in the case of the multicoat system d5 (refinish on overbaked clearcoat without prior partial abrading).

(150) TABLE-US-00038 TABLE 2.31 Steam jet resistance (to DIN 55662, method B, measured after stone-chip exposure of the substrates to DIN EN ISO 20567-1, method B) of multicoat systems d1 to d7 of waterborne basecoat materials D1 and D2 Steam jet results Waterborne basecoat materials D1 and D2 D1 D2 d1 KW0 KW0 d2 KW0 KW0 d3 KW1 KW0 d4 KW0 KW0 d5 KW4 KW0 d6 KW0 KW0 d7 KW0 KW0 Key to steam jet results in stone-chip damage: KW0 = no change in the sample KW1 = slight washout of the damage present KW2 = clearly visible washout of the damage present in a coating film KW3 = complete delamination of a coating film in the region of the jet metal panel KW4 = complete delamination of a coating film beyond the jet region KW5 = detachment of the complete coating film down to the substrate

(151) The results demonstrate that the inventive waterborne basecoat material D2, based on the inventive seed-core-shell acrylate BM2, exhibits no changes of the sample in the steam jet test after prior stone-chip testing in any of the multicoat systems. Particularly in the case of the refinish on overbaked clearcoat without prior partial abrading (multicoat system d5), therefore, it has a significant advantage over the reference D1.