AQUEOUS COATING COMPOSITION COMPRISING A THICKENER PREPARABLE FROM AT LEAST ONE POLYAMIDE AND AT LEAST ONE FURTHER POLYMER

Abstract

The present invention relates to an aqueous coating composition comprising at least one binder (A) comprising at least one polymeric resin (A1), at least one pigment (B), and an aqueous dispersion of at least one thickener (C), where (C) is obtainable by a method comprising at least the steps (1), (2), (3), and (4), namely preparing a dispersion or solution of at least one polyurethane as a polymeric resin (C2) in at least one organic solvent (step (1)), preparing a mixture of the dispersion or solution obtained by step (1) and of a melt or solution of at least one polyamide as at least one polymeric resin (C1) having an acid number in a range from 1 to 200 mg of KOH per g of (C1) (step (2)), adding water to the mixture obtained by step (2) (step (3)), and removing the organic solvent from the mixture obtained by step (3), to give the aqueous dispersion of (C) (step (4)), to the use thereof for at least partly coating an optionally coated substrate with a basecoat film, to a coating method of this kind, and to a substrate coated accordingly.

Claims

1: An aqueous coating composition comprising at least one binder (A) comprising at least one polymeric resin (A1) and optionally at least one crosslinking agent (A2), at least one pigment (B), and an aqueous dispersion of at least one thickener (C), wherein the thickener (C) is obtainable by a method comprising at least (1), (2), (3), and (4): (1) preparing a dispersion or solution of at least one polymeric resin (C2) in at least one organic solvent, the polymeric resin (C2) being a polyurethane, (2) preparing a mixture of the dispersion or solution obtained in (1) and of a melt or solution of at least one polyamide as at least one polymeric resin (C1), which has an acid number in a range from 1 to 200 mg of KOH per g of (CL), (3) adding water to the mixture obtained in (2), and (4) removing the organic solvent from the mixture obtained in (3), to give the aqueous dispersion of the at least one thickener (C).

2: The coating composition as claimed in claim 1, wherein the relative weight ratio of (C1) to (C2), based in each case on their solids content, is in the range from 1:10 to 1:1.5.

3: The coating composition as claimed in claim 1, which has a solids content, in terms of the at least one thickener (C), in a range from 0.5 to 15 wt %, based on the total weight of the coating composition.

4: The coating composition as claimed in claim 1, wherein the polyamide used as polymeric resin (C1) has an acid number in a range from 30 to 120 mg of KOH per g of (C1).

5: The coating composition as claimed in claim 1, wherein the polyamide used as polymeric resin (C1) is at least obtainable by a reaction of at least one polycarboxylic acid selected from the group consisting of aliphatic C.sub.3-C.sub.22 dicarboxylic acids, polymers of aliphatic C.sub.14-C.sub.22 monocarboxylic acids, and mixtures thereof, with at least one aliphatic C.sub.2-C.sub.12 diamine.

6: The coating composition as claimed in claim 1, wherein the thickener (C) has a melting point in the range from 20° C. to 100° C.

7: The coating composition as claimed in claim 1, wherein the pigment (B) comprises at least one effect pigment.

8: The coating composition as claimed in claim 1, wherein the binder (A) comprises at least one polyurethane and/or at least one poly(meth)acrylate and/or at least one polyester as at least one polymeric resin (A1).

9: The coating composition as claimed in claim 1, which comprises at least one further thickener (D) selected from the group consisting of metal silicates, thickeners based on poly(meth)acrylic acid, thickeners based on polyurethanes, polymeric waxes, and mixtures thereof.

10: The coating composition as claimed in claim 9, wherein the relative weight ratio of the thickener (C) to the further thickener (D) is in the range from 80:1 to 1:1, based on their respective solids content.

11. (canceled)

12: A method for at least partly coating an optionally coated substrate with a basecoat film, comprising at least (a) (a) at least partly coating at least one optionally coated substrate with a basecoat film, with the aqueous coating composition as claimed in claim 1.

13: A basecoat film which is obtainable by at least partly coating at least one optionally coated substrate with the aqueous coating composition as claimed in claim 1.

14: A substrate coated at least partly with the aqueous coating composition as claimed in claim 1.

Description

INVENTIVE AND COMPARATIVE EXAMPLES

[0198] Unless indicated otherwise, the amounts in parts are parts by weight, and the amounts in percent are percentages by weight, in each case.

[0199] 1. Preparing Polyamides (C1) Employed Inventively to Prepare the Thickener (C)

[0200] 1.1 General Instructions for Preparing Polyamides (C1):

[0201] At least one polycarboxylic acid (C1a) or a corresponding derivative thereof, such as a corresponding ester or a corresponding anhydride, for example, and optionally at least one organic solvent are introduced in a reaction vessel with stirrer, reflux condenser, and water separator, and are mixed with at least one polyamine (C1b), and this mixture is heated with stirring at a temperature in the range from 160 to 240° C. until the desired amount of water and any organic solvent present has been separated off, this indicating the complete or desired reaction of component (C1a) with component (C1b) for preparing the polyamide (C1).

[0202] Polyamide 1

[0203] Polyamide 1 is prepared by introducing 687.5 g dimerized fatty acid (commercially available product Pripolm 1012 from Croda) and dodecanedicarboxylic acid (57.5 g) in 22.4 g of xylene and heating the resulting mixture M1 to 60° C. 116.20 g of hexamethylenediamine are melted at an oven temperature of 80° C. and added in portions to the mixture M1. After the end of the addition, the mixture is heated first for a duration of 10 minutes at 130 to 140° C., and thereafter at 175° C. This temperature is maintained, and the water formed is removed by distillation. The acid number of the resulting mixture is determined a number of times during this process. The reaction is continued until an acid number of 68.5 mg KOH/g is reached (after about 3 hours).

[0204] Polyamide 2

[0205] Polyamide 2 is prepared by introducing 724.1 g dimerized fatty acid (commercially available product Pripol® 1012 from Croda) in 21.7 g of xylene and heating the resulting mixture M1 to 60° C. 116.2 g of hexamethylenediamine are melted at an oven temperature of 800 and added in portions to the mixture M1. After the end of the addition, the mixture is heated first for a duration of 10 minutes at 130 to 140° C., and thereafter at 175° C. This temperature is maintained, and the water formed is removed by distillation. The acid number of the resulting mixture is determined a number of times during this process. The reaction is continued until an acid number of 37.9 mg KOH/g is reached.

[0206] 2. Preparation of Inventively Employed Thickeners (C)

[0207] 2.1 General Instructions for Preparing Inventively Employed Thickeners (C):

[0208] A melt of at least one polyamide (C1) is prepared. This melt is introduced into a dispersion or solution of at least one polymer (C2) in at least one organic solvent such as MEK, for example. Added to this mixture are water and optionally at least one neutralizing agent. The at least one organic solvent is removed, to give the aqueously dispersed thickener (C).

[0209] Thickener 1

[0210] First of all, 600 g of a solvent-containing dispersion of a polyurethane as a polymer (C2), with a solids fraction of 70 wt %, are introduced and heated to a temperature of 80° C. This solvent-containing polyurethane dispersion is prepared as described in EP 0 228 003 A1, page 8, lines 5 to 16, and comprises methyl ethyl ketone (MEK) as organic solvent. Subsequently a melt of 172.1 g of polyamide 1 (melt obtained by heating at 140° C.) is added in portions over a time of 30 minutes, with stirring, to the solvent-containing polyurethane dispersion. Metered into this mixture thereafter are 37.9 g of dimethylethanolamine (DMEA) over a duration of 30 minutes, and the resulting mixture is stirred for a further 30 minutes. 1693.6 g of deionized water are added to this mixture over a duration of 1 hour, and the mixture is stirred for a time of one hour more. The MEK is removed by distillation and the solids content of the resulting thickener (C) is optionally adjusted by addition of deionized water to 30 wt %, if too much water is removed in the distillative removal of MEK, so that the solids content is >30 wt %. MEQ values as follows were determined: MEQ(acid): 0.683 mmol/g; MEQ(base): 0.695 mmol/g. Thickener 1 is used subsequently in the form of the resulting aqueous dispersion.

[0211] Thickener 2

[0212] First of all, 600 g of a solvent-containing dispersion of a polyurethane as a polymer (C2), with a solids fraction of 70 wt %, are introduced and heated to a temperature of 80° C. This solvent-containing polyurethane dispersion is prepared as described in EP 0 228 003 A1, page 8, lines 5 to 16, and comprises methyl ethyl ketone as organic solvent. Subsequently a melt of 172.1 g of polyamide 2 (melt obtained by heating at 140° C.) is added in portions over a time of 30 minutes, with stirring, to the solvent-containing polyurethane dispersion. Metered into this mixture thereafter are 25.6 g of dimethylethanolamine (DMEA) over a duration of 30 minutes, and the resulting mixture is stirred for a further 30 minutes. 1658.6 g of deionized water are added to this mixture over a duration of 1 hour, and the mixture is stirred for a time of one hour more. The MEK is removed by distillation and the solids content of the resulting thickener (C) is optionally adjusted by addition of deionized water to 25 wt %, if too much water is removed in the distillative removal of MEK, so that the solids content is >25 wt %. MEQ values as follows were determined: MEQ(acid): 0.506 mmol/g; MEQ(base): 0.505 mmol/g. Thickener 2 is used subsequently in the form of the resulting aqueous dispersion.

[0213] 3. Preparation of Inventive Coating Compositions and Comparative Coating Compositions

[0214] 3.1 the Components of the Respective Coating Composition, Specified Below, have the Following Meanings:

[0215] The aqueous dispersion of a polymeric resin (I) is prepared as described on page 20, lines 9 to 21, of DE 199 48 004 A1.

[0216] The aqueous dispersion of a polymeric resin (II) is prepared as described in column 16, lines 37 to 59 of DE 40 09 858 A1, within example D.

[0217] The aqueous dispersion of a polymeric resin (III) is prepared as described on page 7, line 55 to page 8, line 23 of DE 44 37 535 A1.

[0218] The aqueous dispersion of a polymeric resin (IV) is prepared as described on page 8, lines 5 to 20 of EP 0 228 003 A1.

[0219] Rheovis® AS 1130 is a commercially available aqueous solution from BASF SE, containing 30 wt % of thickener based on an acrylic copolymer.

[0220] Rheovis® PU 1250 is a commercially available aqueous butyl diglycol solution from BASF SE, containing 40 wt % of a thickener based on a polyurethane.

[0221] Luwipal® 052 is a melamine-formaldehyde resin from BASF SE.

[0222] Cymel® 203 is a melamine-formaldehyde resin from Allnex.

[0223] Disparlon® AQ630 is a commercially available dispersion of a polyamide from Kusumoto Chemicals Co. Ltd. with a nonvolatile polyamide fraction of 18 wt %.

[0224] Disparlon® AQ600 is a commercially available dispersion of a polyamide from Kusumoto Chemicals Co. Ltd. with a nonvolatile polyamide fraction of 20 wt %.

[0225] Alu Stapa Hydrolux® 2154 & VP56450 are two commercially available aluminum pigments, available from Altana-Eckart.

[0226] Pluriol® E300 is a commercially available polyethylene glycol from BASF SE.

[0227] Agitan® 281 is a commercially available defoamer from Minzing Chemie GmbH.

[0228] The aqueous dispersion of the polyamide 1 is prepared as follows: The polyamide 1 is prepared as described in section 1.1. Subsequently, after attainment of an acid number of 68.5 mg KOH/g (after about 3 hours), the resulting polyamide 1 is cooled to 120° C., 413 g of butyl glycol are added to it, and the resulting mixture is admixed at 100° C. with dimethylethanolamine (DMEA) (85.5 g) and stirred. The resulting mixture is introduced into 1600 g of deionized water which has a temperature of 90-95° C. The resulting mixture is subsequently stirred at 80° C. for 30 minutes and then first cooled to 60° C. and left with stirring. The solids content is 22.6 wt %. MEQ values as follows were determined: MEQ(acid): 1.058 mmol/g; MEQ(base): 1.076 mmol/g.

[0229] The aqueous dispersion of the polyamide 2 is prepared as follows: The polyamide 2 is prepared as described in section 1.1. Subsequently, after attainment of an acid number of 37.9 mg KOH/g, the resulting polyamide 2 is cooled to 120° C., and 200 g of the resulting mixture are then introduced into a mixture of dimethylethanolamine (DMEA) (12.3 g), 0.3 g of Agitan® 281, and 1171.4 g of deionized water which has a temperature of 90-95° C. The solids content is 20.0 wt %. MEQ values as follows were determined: MEQ(acid): 1.460 mmol/g; MEQ(base): 0.595 mmol/g.

[0230] 3.2 General Operating Procedure for Producing Inventive Coating Compositions and Comparative Coating Compositions:

[0231] The components listed under “aqueous phase 1” in each of the tables below are stirred together in the order stated to form an aqueous mixture M1. Subsequently, the components listed under “aqueous phase 2” in the tables below are stirred together in the order stated, to form a second aqueous mixture M2, which is added to the aqueous mixture M1 and stirred for 10 minutes. The result in each case is the aqueous mixture M3. In the next step, an organic mixture is prepared from the components listed under “organic phase” in each of the tables below. The organic mixture is added to the aqueous mixture M3. The combined mixture is then stirred for 10 minutes and adjusted using deionized water and dimethylethanolamine to a pH of 8 and to a defined spray viscosity under a shearing load of 1000 s.sup.−1 as measured with a rotary viscometer (Rheolab QC instrument with C-LTD80/QC conditioning system, from Anton Paar) at 23° C. In the case of coating compositions V1, V2, and 81, a spray viscosity of 90±5 mPa.Math.s is set. In the case of coating composition B2, a spray viscosity of 95±5 mPa-s is set. In the case of each of coating compositions V3, V4, V5, V6, V7, and V5, and also 83, 84, 85, 86, 87, 88, and 89, a spray viscosity of 80±5 mPa-s is set.

[0232] The respective quantity figures in each of the tables below represent parts by weight in each case.

[0233] 3.3 Coating Compositions V1 and V2 (Noninventive) and B1 (Inventive)

TABLE-US-00001 TABLE 1.1 Preparation of V1, V2, and B1 V1 V2 B1 Aqueous phase 1 Aqueous dispersion of a polymeric 21.00 21.00 9.00 resin (I) Deionized water 18.85 26.69 22.29 Butyl glycol 3.33 3.62 3.62 Butanol 1.57 1.57 1.57 Aqueous dispersion of a polymeric 1.65 1.68 1.68 resin (II) Rheovis ® AS 1130 4.75 4.32 4.32 Dimethylethanolamine in water 0.37 0.36 0.36 (10 wt %) Luwipal ® 052 4.11 4.11 4.11 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.41 2.41 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.84 4.84 resin (III) Rheovis ® PU1250 0.99 0.90 0.90 Aqueous phase 2 Deionized water 14.27 — — Dimethylethanolamine in water 0.01 — — (10 wt %) Disparlon ® AQ630 6.39 — — Butyl glycol 0.64 — — Aqueous dispersion of polyamide 2 — 4.60 — Inventively employed thickener 2 — — 21.00 Organic phase Mixture of Alu Stapa Hydrolux ® 5.10 5.10 5.10 2154 & VP56450 Butyl glycol 6.35 6.35 6.35 Aqueous dispersion of a polymeric 1.90 2.16 2.16 resin (II) Dimethylethanolamine in water 0.22 0.22 0.22 (10 wt %)

[0234] 3.4 Coating Composition 82 (Inventive)

TABLE-US-00002 TABLE 1.2 Preparation of B2 B2 Aqueous phase 1 Aqueous dispersion of a polymeric 21.51 resin (I) Deionized water 29.38 Butyl glycol 3.62 Butanol 1.57 Aqueous dispersion of a polymeric 1.68 resin (II) Rheovis ® AS 1130 4.32 Dimethylethanol amine in water 0.36 (10 wt %) Luwipal ® 052 4.11 2,4,7,9-Tetramethyl-5-decynediol 2.41 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.84 resin (III) Rheovis ® AS 1250 0.90 Aqueous phase 2 Inventively employed thickener 2 11.40 Organic phase Mixture of Alu Stapa Hydrolux ® 2154 & VP56450 Butyl glycol 6.35 Aqueous dispersion of a polymeric 2.16 resin (II) Dimethylethanol amine in water 0.22 (10 wt %)

[0235] 3.5 Coating Compositions V3 (Noninventive) and B3 (Inventive)

TABLE-US-00003 TABLE 1.3 Preparation of V3 and B3 V3 B3 Aqueous phase 1 Aqueous dispersion of a polymeric 34.73 28.41 resin (IV) Deionized water 13.02 13.02 Butyl glycol 3.33 3.33 Butanol 2.35 2.35 Rheovis ® AS 1130 0.63 0.63 Deionized water 1.88 1.88 Dimethylethanolamine in water 0.59 0.59 (10 wt %) Cymel ® 203 2.74 2.74 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.51 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.50 resin (III) Aqueous phase 2 Deionized water 12.80 2.51 Dimethylethanolamine in water 0.01 0.01 (10 wt %) Disparlon ® AQ630 3.80 — Butyl glycol 0.51 0.34 Inventively emloyed thickener 1 — 8.56 Organic phase Mixture of Alu Stapa Hydrolux ® 5.10 5.10 2154 & VP56450 Propyl glycol 6.35 6.35

[0236] 3.6 Coating Compositions V4 (Noninventive) and B4 (Inventive)

TABLE-US-00004 TABLE 1.4 Preparation of V4 and B4 V4 B4 Aqueous phase 1 Aqueous dispersion of a polymeric 28.00 13.48 resin (IV) Deionized water 23.80 21.92 n-Butoxypropanol 3.20 3.20 Aqueous dispersion of a polymeric 2.70 2.70 resin (II) Rheovis ® AS 1130 1.00 1.00 Deionized water 5.00 5.00 Dimethylethanolamine in water 0.30 0.30 (10 wt %) Dimethylethanolamine 0.25 0.25 Cymel ® 203 3.70 3.70 Aqueous dispersion of a polymeric 3.60 3.60 resin (III) Aqueous phase 2 Aqueous dispersion of polyamide 2 4.60 — Inventively employed thickener 2 — 21.00 Organic phase Mixture of Alu Stapa Hydrolux ® 5.30 5.30 2154 & VP56450 Butyl glycol 5.75 5.75 Pluriol ® E300 2.80 2.80

[0237] 3.7 Coating Compositions V5 (Noninventive) and B5 (Inventive)

TABLE-US-00005 TABLE 1.5 Preparation of V5 and B5 V5 B5 Aqueous phase 1 Aqueous dispersion of a polymeric 22.30 17.05 resin (I) Deionized water 13.02 13.02 Butyl glycol 3.33 3.33 Butanol 2.35 2.35 Aqueous dispersion of a polymeric 1.65 1.65 resin (II) Aquatix ® 821 1.67 1.67 Dimethylethanolamine in water 0.37 0.37 (10 wt %) Cymel ® 203 2.74 2.74 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.51 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.50 resin (III) Aqueous phase 2 Deionized water 3.25 — Aqueous dispersion of polyamide 2 2.46 — Inventively employed thickener 2 — 8.42 Organic phase Mixture of Alu Stapa Hydrolux ® 5.10 5.10 2154 & VP56450 Butyl glycol 6.35 6.35 Aqueous dispersion of a polymeric 1.90 1.90 resin (II) Dimethylethanolamine in water 0.22 0.22 (10 wt %)

[0238] 3.8 Coating Compositions V6 (Noninventive) and B6 (Inventive)

TABLE-US-00006 TABLE 1.6 Preparation of V6 and B6 V6 B6 Aqueous phase 1 Aqueous dispersion of a polymeric 29.66 23.34 resin (IV) Aqueous solution of an Na Mg 2.00 12.00 phyllosilicate (3 wt %) Deionized water 13.02 13.02 Butyl glycol 3.33 3.33 Butanol 1.57 1.57 Dimethylethanolamine in water 0.37 0.37 (10 wt %) Luwipal ® 052 5.34 5.34 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.51 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.50 resin (III) Aqueous phase 2 Deionized water 7.61 — Disparlon ® AQ630 3.80 — Inventively employed thickener 2 — 8.56 Organic phase Mixture of Alu Stapa Hydrolux ® 5.10 5.10 2154 & VP56450 Butyl glycol 6.35 6.35 Dimethylethanolamine in water 0.22 0.22 (10 wt %)

[0239] 3.9 Coating Compositions V7 (Noninventive) and B7 and 88 (Inventive)

TABLE-US-00007 TABLE 1.7 Preparation of V7, B7 and B8 V7 B7 B8 Aqueous phase 1 Aqueous dispersion of a polymeric 26.84 14..19 14.19 resin (IV) Deionized water 13.02 13.02 13.02 Butyl glycol 3.33 3.62 3.62 Butanol 1.57 1.57 1.57 Aqueous dispersion of a polymeric 1.65 1.65 1.65 resin (II) Rheovis ® AS 1130 0.21 0.21 0.21 Deionized water 0.63 0.63 0.63 Dimethylethanolamine in water 0.37 0.37 0.37 (10 wt %) Luwipal ® 052 3.58 3.56 3.56 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.51 2.51 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.84 4.84 resin (III) Aqueous phase 2 Deionized water 26.34 5.29 5.01 Disparlon ® AQ600 6.84 — — Butyl glycol 1.03 0.68 0.68 Inventively employed thickener 2 — 16.83 — Inventively employed thickener 1 — — 17.10 Organic phase Mixture of Alu Stapa Hydrolux ® 5.10 5.10 5.10 2154 & VP56450 Butyl glycol 6.35 6.35 6.35 Aqueous dispersion of a polymeric 1.90 1.90 1.90 resin (II) Dimethylethanolamine in water 0.22 0.22 0.22 (10 wt %)

[0240] 3.10 Coating Compositions V8 (Noninventive) and B9 (Inventive)

TABLE-US-00008 TABLE 1.8 Preparation of B9 and V8 B9 V8 Aqueous phase 1 Aqueous dispersion of a polymeric 9.00 19.00 resin (I) Deionized water 25.45 26.94 Butyl glycol 3.33 3.47 Butanol 1.57 1.57 Aqueous dispersion of a polymeric 1.65 1.65 resin (II) Rheovis ® AS 1130 4.32 4.75 Dimethylethanolamine in water 0.37 0.40 (10 wt %) Luwipal ® 052 3.60 3.60 2,4,7,9-Tetramethyl-5-decynediol 2.51 2.65 in butyl glycol (52 wt %) Aqueous dispersion of a polymeric 4.50 4.50 resin (III) Rheovis ® PU 1250 0.99 0.99 Aqueous phase 2 Deionized water 8.99 6.12 Agitan ® 281 0.03 0.02 Aqueous dispersion of polyamide 1 — 5.80 Inventively employed thickener 1 15.91 — 2,4,7,9-Tetramethyl-5-decynediol 0.13 0.06 in butyl glycol (52 wt %) Organic phase Mixture of Alu Stapa Hydrolux ® 4.20 4.20 2154 & VP56450 Butyl glycol 6.35 6.99 Aqueous dispersion of a polymeric 1.90 1.90 resin (II) Dimethylethanolamine in water 0.22 0.24 (10 wt %)

[0241] 3.11 Summary of the Inventive Coating Compositions and Comparative Coating Compositions Produced, in Terms of the Thickeners (C) (Inventive) they Each Contain or the Polyamide Components (Noninventive) they Each Contain.

[0242] A corresponding summary is given in Table 1.9 below:

TABLE-US-00009 non- Composition Thickeners inventive inventive V1 Disparlon ® AQ630 X V2 Aqueous dispersion of X polyamide 2 B1 Inventively employed X thickener 2 B2 Inventively employed X thickener 2 V3 Disparlon ® AQ630 X B3 Inventively employed X thickener 1 V4 Aqueous dispersion of X polyamide 2 B4 Inventively employed X thickener 2 V5 Aqueous dispersion of X polyamide 2 B5 Inventively employed X thickener 2 V6 Disparlon ® AQ630 X B6 Inventively employed X thickener 2 V7 Disparlon ® AQ600 X B7 Inventively employed X thickener 2 B8 Inventively employed X thickener 1 B9 Inventively employed X thickener 1 V8 Aqueous dispersion of X polyamide 1

[0243] 4. Tests and Investigations

[0244] 4.1 Investigations into the Incidence of Pinholes

[0245] This investigation takes place in accordance with the method described above. The inventive coating composition B1 and also the comparative coating composition V1 as waterborne basecoat material are applied to a steel panel coated with a primer-surfacer system. Subsequently, as described within the method, a clearcoat material is applied to the resulting respective basecoat films.

[0246] The results are summarized in Table 1.10. The number of pinholes as reported is standardized to 200 cm.sup.2.

[0247] The results demonstrate that the inventive coating composition 81 comprising the inventively employed thickener (C), in comparison to V1, comprising the commercially available polyamide Disparlon® AQ 630, shows an improved profile of properties in relation to pinhole robustness.

[0248] 4.2 Investigations Concerning Storage Stability

[0249] This investigation takes place in accordance with the method described above. The inventive coating composition B2 and also the comparative coating composition V2 are investigated here.

[0250] The results are summarized in Table 1.11.

[0251] The results demonstrate that the inventive coating composition 82 comprising the inventively employed thickener (C), in comparison to V2 comprising the polyamide 2 as such, exhibits a very good storage stability: the rheological behavior of the waterborne basecoat B2 material does not change hardly at all even after two-week storage at 40° C. In contrast, V2 shows a significantly weaker storage stability.

[0252] 4.3 Investigations into the Leveling after Condensation Water Treatment

[0253] This investigation takes place in accordance with the method described above. The inventive coating compositions B1 or B3 and also the comparative coating compositions V2 or V3 are in this test each applied as waterborne basecoat material to a steel panel coated with a primer-surfacer system. Subsequently, as described within the method, a clearcoat material is applied to the resulting respective basecoat films. The results are summarized in Table 1.12.

[0254] The results demonstrate that the inventive coating compositions 31 and 83, comprising the inventively employed thickener (C), in comparison to V1 and V3, which each comprise the polyamide Disparlon® AQ 630 or Disparlon® AQ 600, respectively, have advantages both before and after condensation water exposure, demonstrating that there is no swelling of the multicoat construction, comprising a basecoat film obtained from any of these compositions, that is manifested in high values for LW and/or SW.

[0255] 4.4 Investigations into Angle-Dependent Lightnesses and Flop Indices

[0256] This investigation takes place in accordance with the method described above. The inventive coating composition B4 and also the comparative coating composition V4 are applied, in each case in the form of a waterborne basecoat film, to a steel panel coated with a primer-surfacer system. Subsequently, as described within the method, a clearcoat material is applied to the resulting respective basecoat films.

[0257] The results are summarized in Table 1.13.

[0258] The results demonstrate that the inventive coating composition B4, comprising an inventively employed thickener (C) prepared from the polyamide 2, in comparison to V4, comprising in each case only this polyamide 2 as such, exhibits an improved metallic effect, which is characterized by a greater lightness at the 15° angle and also by a higher flop index.

[0259] 4.5 Investigations into the Incidence of Bits

[0260] This investigation takes place in accordance with the method described above. The inventive coating compositions B5, B6, 87, 38 and B9 and also the comparative coating compositions V5, V6, V7 and V8 are each applied as waterborne basecoat material to a steel panel coated with a primer-surfacer system. Subsequently, as described within the method, a clearcoat material is applied to the resulting respective basecoat films.

[0261] The results are summarized in Table 1.14.

[0262] The results demonstrate that the inventive coating compositions B5, B6, B7, B8 and B9, comprising an inventively employed thickener (C), in comparison to V5, V6, V7 and V8, comprising in each case only a polyamide component, permit significantly improved results in relation to bittiness, as a criterion for the compatibility or incorporability of the thickeners into the coating compositions. From a comparison of the experimental data relating to V6 and B6, moreover, it is apparent that a combination of a polyamide and an Na Mg phyllosilicate results in bittiness, while a combination of an inventive thickener and an Na Mg phyllosilicate does not.

[0263] 4.6 Investigations into the Incidence of Bits

[0264] An inventively employed aqueous dispersion of a thickener (thickener 1) is investigated for the incidence of bits, using the method described above. Analogously, an aqueous comparative dispersion having a solids content of approximately 28 wt % is investigated, which comprises in a fraction of 29 wt % the aqueous dispersion of polyamide 1 (which in turn has a solids fraction of 22.6 wt %) and which also comprises, in a fraction of 71 wt %, the aqueous dispersion of the polymeric resin (IV) (prepared as described on page 8, lines 5 to 20, of EP 0 228 003 A1), which in turn has a solids fraction of 30 wt %, based in each case on the total weight of the comparative dispersion.

[0265] The results are summarized in Table 1.15.

[0266] From table 1.15 is apparent that in the case of the aqueous comparative dispersion, in contrast to the thickener 1, a multiplicity of bits that have occurred is observed. The aqueous comparative dispersion comprises the same polymeric resins (C1) and (C2) which were also used to prepare the thickener 1; in contrast to the production of the thickener 1, which is obtainable by a process comprising at least the steps (1), (2), (3), and (4) necessary in accordance with the invention, however, these polymeric resins were used simply by mixing to prepare the aqueous comparative dispersion. These results show that it is essential to the invention that the thickener (C) used in accordance with the invention is obtained by the process comprising at least the steps (1), (2), (3), and (4) necessary in accordance with the invention.