Hydroxy-functional polyether-based reaction products and aqueous base paint which contains the reaction products

Abstract

Provided herein is a pigmented aqueous basecoat material including a hydroxy-functional polyether-based reaction product that is prepared by a urethane group-forming reaction of: (a) at least one component including isocyanate groups that is prepared by the urethane group-forming reaction of at least one organic diisocyanate (a1) with at least one polyether (a2) 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 a polyether (b) possesses a number-average molecular weight of 500 to 5000 g/mol,
the components (a1) and (a2) being used in a molar ratio of 1.8/1.7 to 3.0/1.0, and the resulting component (a) having an isocyanate content of 0.5 to 10.0% with (b) at least one organic polyol.

Claims

1. A method for producing a multicoat paint system by: (1) applying a pigmented aqueous basecoat material to a substrate via spraying, (2) forming a polymer film from the pigmented aqueous basecoat material applied in step (1), (3) applying a clearcoat material to the polymer film, and subsequently (4) curing the pigmented aqueous basecoat material together with the clearcoat material, wherein the pigmented aqueous basecoat material used in step (1) comprises a hydroxy-functional polyether-based reaction product that is preparable by urethane group-forming reaction of: (a) at least one component containing isocyanate groups that is preparable by urethane group-forming reaction of at least one organic diisocyanate (a1) with at least one polyether (a2) of the general structural formula (I), ##STR00004## wherein R is a C.sub.3 to C.sub.6 alkylene radical, and n is selected accordingly such that the polyether (a2) possesses a number-average molecular weight of 500 to 5000 g/mol, wherein the components (a1) and (a2) are used in a molar ratio of 1.8/1.7 to 3.0/1.0, and a resulting component (a) has an isocyanate content of 1.0 to 6.5%, with (b) at least one organic polyol, wherein the amounts of components (a) and (b) are harmonized with one another such that the ratio of the molar amount of isocyanate groups in component (a) to the molar amount of component (b) is in a range from 0.33 to 0.95, and the resulting reaction product has a number-average molecular weight of 700 to 20,000 g/mol.

2. The method as claimed in claim 1, wherein the polyether (a2) possesses a number-average molecular weight of 600 to 3,200 g/mol.

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

4. The method as claimed in claim 1, wherein the amounts of components (a) and (b) are harmonized with one another in such a way that the ratio of the molar amount of isocyanate groups in component (a) to the molar amount of component (b) is in a range from 0.40 to 0.85.

5. The method as claimed in claim 1, wherein the polyether-based reaction product possesses a number-average molecular weight of 1,500 to 12,000 g/mol.

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

7. The method as claimed in claim 1, further comprising a melamine resin and also a polyurethane resin that is grafted by means of olefinically unsaturated monomers and that further comprises hydroxyl groups.

8. The method as claimed in claim 1, wherein the component (b) has three hydroxyl groups.

9. The method as claimed in claim 1, 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.

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

11. A multicoat paint system producible by the method as claimed in claim 1.

Description

EXAMPLES

(1) Determination of the Number-Average Molecular Weight:

(2) 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. Schröder, G. Müller, 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).

(3) Isocyanate Content:

(4) The isocyanate content, also referred to hereinafter as NCO content, is determined by adding an excess of a 2% strength N,N-dibutylamine solution in xylene to a homogeneous solution of the samples in acetone/N-ethyl-pyrrolidone (1:1 vol %), by potentiometric back-titration of the amine excess with 0.1 N hydrochloric acid in accordance with DIN EN ISO 3251, DIN EN ISO 11909 and DIN EN ISO 14896. Via the fraction of a component (solid body) in solution it is possible to calculate back to the NCO content of the component per se. The NCO content therefore indicates the weight-based percentage fraction of NCO groups as a proportion of the total weight of the respective component.

(5) Production of Inventive Reaction Products (IR) and Also of Reaction Products Used for Comparison (CR):

(6) IR1:

(7) In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer, condenser, 466.8 g of isophorone diisocyanate, 918 g of methyl ethyl ketone, 910 g of PolyTHF650 (from BASF SE) with an OH number of 172 mg KOH/g (1.4 mol), and 0.69 g of dibutyltin dilaurate are heated to 80° C. This temperature is maintained until the NCO content, based on the solids content of the solution, is constant and is in a range from 2.0 to 2.1% (thus corresponding to the NCO content of component (a)). At this point 150 g of trimethylolpropane are added and the temperature stated above is further maintained until the NCO value has reached less than 0.1%. Thereafter the methyl ethyl ketone is removed by distillation under reduced pressure down to a level of less than 0.5%, and the resulting resin is diluted at 80° C. with 640 g of butyl glycol.

(8) The solids content of the resin solution is 67% (measured at 130° C. for 1 h in a forced air oven on a 1 g sample with addition of 1 ml of methyl ethyl ketone)

(9) Number-average molecular weight (vapor pressure osmosis): 2400 g/mol

(10) Viscosity 50% in butyl glycol: 2940 mPas (measured at 23° C. using a Brookfield CAP 2000+ rotary viscometer, spindle 3, shear rate: 750 s.sup.−1).

(11) IR2:

(12) In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer, condenser, 382.3 g of isophorone diisocyanate, 1401 g of methyl ethyl ketone, 1720 g of PolyTHF2000 (from BASF SE) with an OH number of 56 mg KOH/g (0.86 mol), and 1.05 g of dibutyltin dilaurate are heated to 80° C. This temperature is maintained until the NCO content, based on the solids content of the solution, is constant and is in a range from 1.6% to 1.7% (thus corresponding to the NCO content of component (a)). At this point 179 g of trimethylolpropane are added and the temperature stated above is further maintained until the NCO value has reached less than 0.1%. Thereafter the methyl ethyl ketone is removed by distillation under reduced pressure down to a level of less than 0.5%, and the resulting resin is diluted at 80° C. with 570 g of butyl glycol.

(13) The solids content of the resin solution is 78% (measured at 130° C. for 1 h in a forced air oven on a 1 g sample with addition of 1 ml of methyl ethyl ketone)

(14) Number-average molecular weight (vapor pressure osmosis): 2600 g/mol

(15) Viscosity 50% in butyl glycol: 3475 mPas (measured at 23° C. using a Brookfield CAP 2000+ rotary viscometer, spindle 3, shear rate: 750 s.sup.−1).

(16) CR1:

(17) The reaction product used for comparison was a polyester prepared according to example D, column 16, lines 37 to 59 of DE 4009858 A, the organic solvent used being butyl glycol rather than butanol, meaning that solvents present are butyl glycol and water. The corresponding dispersion of the polyester has a solids content of 60 wt %.

(18) Preparation of Aqueous Basecoat Materials

(19) 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.

(20) 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).

(21) 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).

(22) All proportions indicated in the tables are parts by weight.

(23) Preparation of a Non-Inventive Waterborne Basecoat Material 1

(24) 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.

(25) 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)
Preparation of Blue Paste:

(26) 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.

(27) Preparation of Carbon Black Paste:

(28) 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, 1.45 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.

(29) Preparation of the Mica Slurry:

(30) 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 27—example 2), and 1.3 parts by weight of the commercial Mica Mearlin Ext. Fine Violet 539V from Merck.

(31) Preparation of Inventive Waterborne Basecoat Materials I1 and I2

(32) 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 respectively the same, through compensation of the amount of solvent and/or consideration of the solids content of the component to be added.

(33) 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
Comparison Between Waterborne Basecoat Materials 1 and I1, I2
Stonechip Resistance:

(34) For the determination of the stonechip resistance, the multicoat paint systems were produced according to the following general protocol:

(35) The substrate used was a steel panel with dimensions of 10×20 cm, coated with a cathodic e-coat (cathodic electrocoat).

(36) Applied to this panel first of all was the respective basecoat material (table B), applied pneumatically with a target film thickness (dry film thickness) of 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 with a target film thickness (dry film thickness) of 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.

(37) 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.

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

(39) 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

(40) 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.

(41) Preparation of a Non-Inventive Waterborne Basecoat Material 2

(42) The components listed under “Aqueous phase” in table C were stirred together in the order stated to form an aqueous mixture. The mixture was 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.

(43) 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 deionized water, 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-dimethyl- 0.4 ethanolamine (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
Preparation of Carbon Black Paste:

(44) 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, 1.45 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.

(45) Preparation of White Paste:

(46) 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.

(47) Preparation of Inventive Waterborne Basecoat Materials I3 and I4

(48) The waterborne basecoat materials I3 and I4 were prepared in analogy to table C, but using the reaction product IR1 (waterborne basecoat material 13) or the reaction product IR2 (waterborne basecoat material 14) in place of CR1. The proportion used of the reaction product IR1 or IR2 was respectively the same, through compensation of the amount of solvent and/or consideration of the solids content of the component to be added.

(49) 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
Preparation of a Non-Inventive Waterborne Basecoat Material 3

(50) 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.

(51) 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 deionized water, 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-dimethyl- 1.356 ethanolamine (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)
Preparation of Blue Paste:

(52) 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.

(53) Comparison of Waterborne Basecoat Materials 2 and I3, I4

(54) For the determination of the stonechip resistance, the multicoat paint systems were produced according to the following general protocol:

(55) The substrate used was a steel panel with dimensions of 10×20 cm, coated with a cathodic e-coat.

(56) Applied to this panel first of all was the respective basecoat material (table D), which was applied with a target film thickness (dry film thickness) of 20 micrometers. After the basecoat had been flashed at room temperature for 4 minutes, the waterborne basecoat material 3 was applied in a target film thickness (dry film thickness) of 20 micrometers, followed by flashing at room temperature for 4 minutes and then by 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 with a target film thickness (dry film thickness) of 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.

(57) The results are found in table 2. The waterborne basecoat material (WBM) detail indicates which WBM was used in the particular multicoat paint system.

(58) TABLE-US-00007 TABLE 2 Stonechip resistance of the waterborne basecoat materials 2 and I3, I4 WBM Stonechip result  2 + 3 2.0 I3 + 3 1.5 I4 + 3 1.5

(59) The results emphasize again that the use of the inventive reaction products in basecoat materials increases the stonechip resistance by comparison with non-inventive systems.