CARBOXY-FUNCTIONAL POLYETHER-BASED REACTION PRODUCTS AND AQUEOUS BASE COATS CONTAINING THE REACTION PRODUCTS

Abstract

A pigmented aqueous basecoat material is disclosed. The pigmented aqueous basecoat material includes a polyether-based reaction product which is preparable by a reaction of trimesic acid with at least one polyether of the general structural formula (I)

##STR00001##

R is a C.sub.3 to C.sub.6 alkylene radical and n is selected accordingly such that the at least one polyether possesses a number-average molecular weight of 500 to 5000 g/mol. The trimesic acid and the at least one polyether are used in the reaction in a molar ratio of 0.7/2.3 to 1.6/1.7 and the resulting reaction product possesses an acid number of 10 to 50 mg KOH/g.

Claims

1. A pigmented aqueous basecoat material comprising a polyether-based reaction product which is preparable by a reaction of (a) trimesic acid with (b) at least one polyether of a general structural formula (I) ##STR00004## in which R is a C.sub.3 to C.sub.6 alkylene radical and n is selected accordingly such that the polyether (b) possesses a number-average molecular weight of 500 to 5000 g/mol, the components (a) and (b) being used in the reaction in a molar ratio of 0.7/2.3 to 1.6/1.7 and the resulting reaction product possessing an acid number of 5 to 50 mg KOH/g.

2. The pigmented aqueous basecoat material as claimed in claim 1, wherein the polyether (b) possesses a number-average molecular weight of 1500 to 3200 g/mol.

3. The pigmented aqueous basecoat material as claimed in claim 1, wherein the group R in the general structural formula (I) comprises tetramethylene radicals.

4. The pigmented aqueous basecoat material as claimed in claim 1, wherein the components (a) and (b) are used in a molar ratio of 0.45/1 to 0.55/1.

5. The pigmented aqueous basecoat material as claimed in claim 1, wherein the polyether-based reaction product possesses a number-average molecular weight of 1500 to 15 000 g/mol.

6. The pigmented aqueous basecoat material as claimed in claim 1, which has an acid number of 10 to 30 mg KOH/g.

7. The pigmented aqueous basecoat material as claimed in claim 1, wherein a sum total of the weight-percentage fractions, based on a total weight of the pigmented aqueous basecoat material, of all polyether-based reaction products is 0.1 to 20 wt %.

8. The pigmented aqueous basecoat material as claimed in claim 1, further comprising a melamine resin and a polyurethane resin that is grafted by means of olefinically unsaturated monomers and that further comprises hydroxyl groups.

9. A polyether-based reaction product which is preparable by a reaction of (a) trimesic acid with (b) at least one polyether of a general structural formula (I) ##STR00005## in which R is a C.sub.3 to C.sub.6 alkylene radical and n is selected accordingly such that the polyether (b) possesses a number-average molecular weight of 500 to 5000 g/mol, the components (a) and (b) being used in the reaction in a molar ratio of 0.7/2.3 to 1.6/1.7 and the resulting reaction product possessing an acid number of 5 to 50 mg KOH/g.

10. A method for improving a stonechip resistance of paint systems produced using a pigmented aqueous basecoat material comprising utilizing a reaction product as claimed in claim 9 in the pigmented aqueous basecoat material.

11. A method for producing a multicoat paint system comprising the steps of (1) applying a pigmented aqueous basecoat material to a substrate, (2) forming a polymer basecoat film from the pigmented aqueous basecoat material applied in step (1), (3) applying a clearcoat material to the resultant polymer basecoat film, and subsequently (4) curing the polymer basecoat film together with the clearcoat, wherein the pigmented aqueous basecoat material as claimed in claim 1 is used in step (1).

12. The method as claimed in claim 11, wherein the substrate from step (1) is a metallic substrate coated with a cured electrocoat, and all coats applied to the electrocoat are cured jointly.

13. The method as claimed in claim 11, wherein the substrate from step (1) is a metal or plastics substrate.

14. A multicoat paint system producible by the method as claimed in claim 11.

Description

EXAMPLES

[0153] Determination of the Number-Average Molecular Weight:

[0154] The number-average molecular weight was determined by means of vapor pressure osmosis. Measurement took place using a vapor pressure osmometer (model 10.00 from Knauer) on concentration series of the test component in toluene at 50 C. with benzophenone as calibration compound for the determination of the experimental calibration constant of the instrument used (according to E. Schroder, G. Mller, K.-F. Arndt, Leitfaden der Polymercharakterisierung [Principles of polymer characterization], Academy-Verlag, Berlin, pp. 47-54, 1982, where the calibration compound used was in fact benzil).

[0155] Production of Inventive Reaction Products (IR) and also of Reaction Products used for Comparison (CR):

[0156] IR1:

[0157] In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer, condenser, thermometer for overhead temperature measurement, and water separator, 105 g of trimesic acid and 2000 g of PolyTHF2000 (from BASF SE) with an OH number of 56 mg KOH/g (1.0 mol) were heated over the course of 3 hours to a product temperature of 220 C. (OH number determination according to DIN 53240). The progress of the reaction was monitored via the determination of the acid number. When an acid number of about 13.5 mg KOH/g was reached, the batch was cooled to below 140 C. and diluted with butyl glycol to a solids content of 90%. A slightly yellowish resin which is viscous at room temperature and has an acid number of 13.1 mg KOH/g (based on solids content) is obtained.

[0158] Number-average molecular weight (vapor pressure osmosis): 3900 g/mol

[0159] Viscosity 65% in butyl glycol: 3500 mPas (measured at 23 C. using a Brookfield CAP 2000+ rotary viscometer, spindle 3, shear rate: 5000 s.sup.1).

[0160] IR2:

[0161] In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer, condenser, thermometer for overhead temperature measurement, and water separator, 42.03 g of trimesic acid and 1160 g of PolyTHF2900 (INVISTA, Wichita, Kans., USA) with an OH number of 38.7 mg KOH/g (0.4 mol) were heated over the course of 3 hours to a product temperature of 220 C. (OH number determination according to DIN 53240). The progress of the reaction was monitored via the determination of the acid number. When an acid number of about 12.1 mg KOH/g was reached, the batch was cooled to below 140 C. and diluted with butyl glycol to a solids content of 90%. A slightly yellowish resin which is viscous at room temperature and has an acid number of 10.9 mg KOH/g (based on solids content) is obtained.

[0162] Number-average molecular weight (vapor pressure osmosis): 4300 g/mol

[0163] Viscosity 65% in butyl glycol: 3770 mPas (measured at 23 C. using a Brookfield CAP 2000+ rotary viscometer, spindle 3, shear rate: 5000 s.sup.1).

[0164] CR1:

[0165] A polyester prepared as per example D, column 16, lines 37 to 59 of DE 4009858 A served as reaction product used for comparison, butyl glycol being used as organic solvent instead of butanol, that is to say butyl glycol and water are present as solvents. The corresponding dispersion of the polyester has a solids content of 60 wt %.

[0166] Preparation of Aqueous Basecoat Materials

[0167] The following should be taken into account regarding formulation constituents and amounts thereof as indicated in the tables hereinafter. When reference is made to a commercial product or to a preparation protocol described elsewhere, the reference, independently of the principal designation selected for the constituent in question, is to precisely this commercial product or precisely the product prepared with the referenced protocol.

[0168] Accordingly, where a formulation constituent possesses the principal designation melamine-formaldehyde resin and where a commercial product is indicated for this constituent, the melamine-formaldehyde resin is used in the form of precisely this commercial product. Any further constituents present in the commercial product, such as solvents, must therefore be taken into account if conclusions are to be drawn about the amount of the active substance (of the melamine-formaldehyde resin).

[0169] If, therefore, reference is made to a preparation protocol for a formulation constituent, and if such preparation results, for example, in a polymer dispersion having a defined solids content, then precisely this dispersion is used. The overriding factor is not whether the principal designation that has been selected is the term polymer dispersion or merely the active substance, as for example polymer, polyester or polyurethane-modified polyacrylate. This must be taken into account if conclusions are to be drawn concerning the amount of the active substance (of the polymer).

[0170] All proportions indicated in the tables are parts by weight.

[0171] Preparation of a Non-Inventive Waterborne Basecoat Material 1

[0172] The components listed under Aqueous phase in table A were stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture was prepared from the components listed under Organic phase. The organic mixture was added to the aqueous mixture. The combined mixtures were then stirred for 10 minutes and adjusted using deionized water and dimethylethanolamine to a pH of 8 and to a spray viscosity of 58 mPas under a shearing load of 1000 s.sup.1, measured using a rotational viscometer (Rheomat RM 180 instrument from Mettler-Toledo) at 23 C.

TABLE-US-00001 TABLE A Waterborne basecoat material 1 Component Parts by weight Aqueous phase Aqueous solution of 3% sodium 27 lithium magnesium phyllosilicate Laponite RD (from Altana-Byk) and 3% Pluriol P900 (from BASF SE) Deionized water 15.9 Butyl glycol (from BASF SE) 3.5 Hydroxy-functional, polyurethane- 2.4 modified polyacrylate; prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 50 wt % strength solution of 0.2 Rheovis PU 1250 (BASF SE) in butyl glycol, rheological agent CR1 2.5 TMDD 50% BG (from BASF SE), 52% 1.2 strength solution of 2,4,7,9- tetramethyl-5-decyne-4,7-diol in butyl glycol Luwipal 052 (from BASF SE), 4.7 melamine-formaldehyde resin 10% strength solution of N,N- 0.5 dimethylethanolamine (from BASF SE) in water Polyurethane-based graft copolymer; 19.6 prepared in analogy to DE 19948004 A1 (page 27 - example 2) Isopropanol (from BASF SE) 1.4 Byk-347 (from Altana-Byk) 0.5 Pluriol P900 (from BASF SE) 0.3 Tinuvin 384-2 (from BASF SE) 0.6 Tinuvin 123 (from BASF SE) 0.3 Carbon black paste 4.3 Blue paste 11.4 Mica slurry 2.8 Organic phase Aluminum pigment (from Altana- 0.3 Eckart) Butyl glycol (from BASF SE) 0.3 Polyurethane-based graft copolymer; 0.3 prepared in analogy to DE 19948004 A1 (page 27 - example 2)

[0173] Preparation of Blue Paste:

[0174] The blue paste was prepared from 69.8 parts by weight of an acrylated polyurethane dispersion prepared as per international patent application WO 91/15528, binder dispersion A, 12.5 parts by weight of Paliogen Blue L 6482, 1.5 parts by weight of dimethylethanolamine (10% strength in DI water), 1.2 parts by weight of a commercial polyether (Pluriol P900 from BASF SE), and 15 parts by weight of deionized water.

[0175] Preparation of Carbon Black Paste:

[0176] The carbon black paste was prepared from 25 parts by weight of an acrylated polyurethane dispersion prepared as per international patent application WO 91/15528, binder dispersion A, 10 parts by weight of carbon black, 0.1 part by weight of methyl isobutyl ketone, 1.36 parts by weight of dimethylethanolamine (10% strength in DI water), 2 parts by weight of a commercial polyether (Pluriol P900 from BASF SE), and 61.45 parts by weight of deionized water.

[0177] Preparation of the Mica Slurry:

[0178] The mica slurry was obtained by using a stirring element to mix 1.5 parts by weight of polyurethane-based graft copolymer, prepared in an analogy to DE 19948004 A1 (page 27example 2), and 1.3 parts by weight of the commercial Mica Mearlin Ext. Fine Violet 539V from Merck.

[0179] Preparation of the inventive waterborne basecoat materials I1 and I2

[0180] The waterborne basecoat materials I1 and I2 were prepared in analogy to table A, but using the reaction product IR1 (waterborne basecoat material I1) or the reaction product IR2 (waterborne basecoat material I2) in place of CR1. The proportion used of the reaction product IR1 or IR2 was the same in each case, through compensation of the amount of solvent and/or through consideration of the solids content of the component to be added.

TABLE-US-00002 TABLE B Basecoat materials 1, I1 and I2 Reaction product Waterborne basecoat material 1 CR1 Waterborne basecoat material I1 IR1 Waterborne basecoat material I2 IR2

[0181] Comparison Between Waterborne Basecoat Materials 1 and I1, I2

[0182] Stonechip Resistance:

[0183] For the determination of the stonechip resistance, the multicoat paint systems were produced according to the following general protocol:

[0184] The substrate used was a steel panel with dimensions of 1020 cm, coated with a cathodic e-coat (cathodic electrocoat).

[0185] Applied to this panel first of all was the respective basecoat material (table B), applied pneumatically in a target film thickness (dry film thickness) at 20 micrometers. After the basecoat had been flashed at room temperature for 1 minute, it was subjected to interim drying in a forced air oven at 70 C. for 10 minutes. Over the interim-dried waterborne basecoat, a customary two-component clearcoat material was applied in a target film thickness (dry film thickness) at 40 micrometers. The resulting clearcoat was flashed at room temperature for 20 minutes. The waterborne basecoat and the clearcoat were subsequently cured in a forced air oven at 160 C. for 30 minutes.

[0186] The resulting multicoat paint systems were tested for their stonechip resistance. This was done using the stonechip test of DIN 55966-1. The results of the stonechip test were assessed in accordance with DIN EN ISO 20567-1. Lower values represent better stonechip resistance.

[0187] The results are found in table 1. The waterborne basecoat material (WBM) detail indicates which WBM was used in the particular multicoat paint system.

TABLE-US-00003 TABLE 1 Stonechip resistance of waterborne basecoat materials 1 and I1, I2 WBM Stonechip outcome .sup.1 2.5 I1 1.5 I2 1.5

[0188] The results emphasize that the use of the inventive reaction products in basecoat materials significantly increases the stonechip resistance by comparison with the waterborne basecoat material 1.

[0189] Preparation of a Noninventive Waterborne Basecoat Material 2

[0190] The components listed under Aqueous phase in table C were stirred together in the order stated to form an aqueous mixture. The combined mixtures were then stirred for 10 minutes and adjusted using deionized water and dimethylethanolamine to a pH of 8 and to a spray viscosity of 58 mPas under a shearing load of 1000 s.sup.1, measured using a rotational viscometer (Rheomat RM 180 instrument from Mettler-Toledo) at 23 C.

TABLE-US-00004 TABLE C Waterborne basecoat material 2 Component Parts by weight Aqueous phase Aqueous solution of 3% sodium 14 lithium magnesium phyllosilicate Laponite RD (from Altana-Byk) and 3% Pluriol P900 (from BASF SE) Deionized water 16 Butyl glycol (from BASF SE) 1.4 CR1 2.3 10 wt % strength solution of 6 Rheovis AS 1130 (BASF SE) in butyl glycol, rheological agent TMDD 50% BG (from BASF SE), 52% 1.6 strength solution of 2,4,7,9- tetramethyl-5-decyne-4,7-diol in butyl glycol Cymel 1133 (from Cytec), melamine- 5.9 formaldehyde resin 10% strength solution of N,N- 0.4 dimethylethanolamine (from BASF SE) in water Polyurethane dispersion - prepared 20 as per WO 92/15405 (page 14, line 13 to page 15, line 28) 2-Ethylhexanol (from BASF SE) 3.5 Triisobutyl phosphate (from Bayer) 2.5 Nacure 2500 (from King Industries) 0.6 White paste 24 Carbon black paste 1.8

[0191] Preparation of the Carbon Black Paste:

[0192] The carbon black paste was prepared from 25 parts by weight of an acrylated polyurethane dispersion prepared as per international patent application WO 91/15528, binder dispersion A, 10 parts by weight of carbon black, 0.1 part by weight of methyl isobutyl ketone, 1.36 parts by weight of dimethylethanolamine (10% strength in DI water), 2 parts by weight of a commercial polyether (Pluriol P900 from BASF SE), and 61.45 parts by weight of deionized water.

[0193] Preparation of the White Paste:

[0194] The white paste was prepared from 43 parts by weight of an acrylated polyurethane dispersion prepared as per international patent application WO 91/15528, binder dispersion A, 50 parts by weight of titanium rutile 2310, 3 parts by weight of 1-propoxy-2-propanol, and 4 parts by weight of deionized water.

[0195] Preparation of the Inventive Waterborne Basecoat Materials I3 and I4

[0196] The waterborne basecoat materials I3 and I4 were prepared in analogy to table C, but using the reaction product IR1 (waterborne basecoat material I3) and, respectively, the reaction product IR2 (waterborne basecoat material I4) in place of CR1. The same proportion of the reaction product IR1 and IR2, respectively, was used in each case, through compensation of the amount of solvent and/or through consideration of the solids content of the component to be added.

TABLE-US-00005 TABLE D Basecoat materials 2, I3 and I4 Reaction product Waterborne basecoat material 2 CR1 Waterborne basecoat material I3 IR1 Waterborne basecoat material I4 IR2

[0197] Preparation of a Noninventive Waterborne Basecoat Material 3

[0198] The components listed under Aqueous phase in table E were stirred together in the order stated to form an aqueous mixture. In the next step, an organic mixture was prepared from the components listed under Organic phase. The organic mixture was added to the aqueous mixture. The combined mixtures were then stirred for 10 minutes and adjusted using deionized water and dimethylethanolamine to a pH of 8 and to a spray viscosity of 58 mPas under a shearing load of 1000 s.sup.1, measured using a rotational viscometer (Rheomat RM 180 instrument from Mettler-Toledo) at 23 C.

TABLE-US-00006 TABLE E Waterborne basecoat material 3 Component Parts by weight Aqueous phase Aqueous solution of 3% sodium 20.35 lithium magnesium phyllosilicate Laponite RD (from Altana-Byk) and 3% Pluriol P900 (from BASF SE) Deionized water 17.27 Butyl glycol (from BASF SE) 2.439 Hydroxy-functional, polyurethane- 2.829 modified polyacrylate; prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A1 50 wt % strength solution of 0.234 Rheovis PU 1250 (BASF SE) in butyl glycol, rheological agent 10 wt % strength solution of 4.976 Rheovis AS 1130 (BASF SE) in butyl glycol, rheological agent TMDD 50% BG (from BASF SE), 52% 1.317 strength solution of 2,4,7,9- tetramethyl-5-decyne-4,7-diol in butyl glycol Cymel 1133 (from Cytec), melamine- 3.512 formaldehyde resin 10% strength solution of N,N- 1.356 dimethylethanolamine (from BASF SE) in water Polyurethane dispersion - prepared 24.976 as per WO 92/15405 (page 14, line 13 to page 15, line 28) Isopropanol (from BASF SE) 1.659 Byk-347 (from Altana-Byk) 0.537 Pluriol P900 (from BASF SE) 0.39 2-Ethylhexanol (from BASF SE) 1.854 Triisobutyl phosphate (from Bayer) 1.151 Nacure 2500 (from King Industries) 0.39 Tinuvin 384-2 (from BASF SE) 0.605 Tinuvin 123 (from BASF SE) 0.39 Blue paste 0.605 Organic phase Aluminum pigment 1 (from Altana- 4.585 Eckart) Aluminum pigment 2 (from Altana- 0.907 Eckart) Butyl glycol (from BASF SE) 3.834 Polyurethane-based graft copolymer; 3.834 prepared in analogy to DE 19948004 A1 (page 27 - example 2)

[0199] Preparation of the Blue Paste:

[0200] The blue paste was prepared from 69.8 parts by weight of an acrylated polyurethane dispersion prepared as per international patent application WO 91/15528, binder dispersion A, 12.5 parts by weight of Paliogen Blue L 6482, 1.5 parts by weight of dimethylethanolamine (10% strength in DI water), 1.2 parts by weight of a commercial polyether (Pluriol P900 from BASF SE), and 15 parts by weight of deionized water.

[0201] Comparison Between Waterborne Basecoat Materials 2 and I3, I4

[0202] For the determination of the stonechip resistance, the multicoat paint systems were produced according to the following general protocol:

[0203] The substrate used was a steel panel with dimensions of 1020 cm, coated with a cathodic e-coat.

[0204] The respective basecoat material (table D) was first of all applied to this panel in a target film thickness (dry film thickness) at 20 micrometers. After flashing of the basecoat material at room temperature for 4 minutes, the waterborne basecoat material 3 was applied in a target film thickness (dry film thickness) at 20 micrometers, then flashed at room temperature for 4 minutes and then subjected to interim drying in a forced air oven at 70 C. for 10 minutes. Over the interim-dried waterborne basecoat, a customary two-component clearcoat material was applied in a target film thickness (dry film thickness) at 40 micrometers. The resulting clearcoat was flashed at room temperature for 20 minutes. The waterborne basecoat and the clearcoat were subsequently cured in a forced air oven at 160 C. for 30 minutes.

[0205] The results are found in table 2. The specification of the waterborne basecoat material (WBM) indicates in each case which WBM was used in the respective multicoat paint system.

TABLE-US-00007 TABLE 2 Stonechip resistance of the waterborne basecoat materials 2 and I3, I4 WBM Stonechip result 2 + 3 2.5 I3 + 3 1.5 I4 + 3 1.5

[0206] The results again emphasize that the use of the inventive reaction products in basecoat materials significantly increases the stonechip resistance in comparison to noninventive systems.