Reaction products and aqueous basecoat materials comprising said products

Abstract

A pigmented aqueous basecoat material that includes a reaction product obtained by reacting (a) a compound of formula (I) with (b) a compound of formula (II) at a molar ratio of 2.3/0.7 to 1.7/1.6, the reaction product having a number-average molecular weight of 500 to 15,000 g/mol, an acid number of less than 10 mg KOH/g, and a hydroxyl number of 25 to 250 mg KOH/g:
X.sub.1YX.sub.2(I), wherein: X.sub.1 and X.sub.2 are each independently an epoxide-reactive functional group, or hydrogen, where at least one of X.sub.1 and X.sub.2 is the epoxide-reactive functional group; and Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having a number-average molecular weight of 100 to 2,500 g/mol, ##STR00001## wherein R is a C.sub.3 to C.sub.6 alkylene radical and n is selected such that compound (b) possesses an epoxide equivalent weight of 100 to 2,000 g/mol.

Claims

1. A pigmented aqueous basecoat material, comprising: a reaction product which is prepared by reaction of (a) at least one compound of formula (I):
X.sub.1YX.sub.2(I) wherein X.sub.1, X.sub.2, independently of one another, are each a functional group which is reactive toward epoxide groups, or hydrogen, with, however, at least one of the two groups X.sub.1 and X.sub.2 being a functional group which is reactive toward epoxide groups, and Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having a number-average molecular weight of 100 to 2 500 g/mol, with (b) at least one compound of formula (II): ##STR00004## wherein R is a C.sub.3 to C.sub.6 alkylene radical, and n is selected accordingly such that the compound (b) possesses an epoxide equivalent weight of 100 to 2 000 g/mol, wherein a molar ratio of all of the compounds (a) to all of the compounds (b) used in the reaction is from 2.3/0.7 to 1.7/1.6 and the reaction product possesses a number-average molecular weight of 500 to 15 000 g/mol, an acid number of less than 10 mg KOH/g, and a hydroxyl number of 25 to 250 mg KOH/g.

2. The pigmented aqueous basecoat material as claimed in claim 1, wherein the compound (b) possesses an epoxide equivalent weight of 150 to 1 200 g/mol.

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

4. The pigmented aqueous basecoat material as claimed in claim 1, wherein the reaction product possesses a number-average molecular weight of 750 to 10 000 g/mol.

5. The pigmented aqueous basecoat material as claimed in claim 1, wherein dimer diols are used as compound (a).

6. The pigmented aqueous basecoat material as claimed in claim 5, wherein the molar ratio of all of the compounds (a) to all of the compounds (b) used in the reaction is from 2.1/0.9 to 1.8/1.5.

7. The pigmented aqueous basecoat material as claimed in claim 1, wherein araliphatic monoalcohols are used as compound (a).

8. The pigmented aqueous basecoat material as claimed in claim 7, wherein the molar ratio of all of the compounds (a) to all of the compounds (b) used in the reaction is from 2.1/0.9 to 2/1.

9. The pigmented aqueous basecoat material 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 the reaction products is 0.1 to 30 wt %.

10. The pigmented aqueous basecoat material as claimed in claim 1, which comprises a polyurethane resin that is grafted with olefinically unsaturated monomers and that also comprises hydroxyl groups, and a melamine resin.

11. A reaction product prepared by reaction of (a) at least one compound of formula (I):
X.sub.1YX.sub.2(I), wherein X.sub.1, X.sub.2, independently of one another, are each a functional group which is reactive toward epoxide groups, or hydrogen, with, however, at least one of the two groups X.sub.1 and X.sub.2 being a functional group which is reactive toward epoxide groups, and Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having a number-average molecular weight of 100 to 2 500 g/mol, with (b) at least one compound of formula (II): ##STR00005## wherein R is a C.sub.3 to C.sub.6 alkylene radical, and n is selected accordingly such that the compound (b) possesses an epoxide equivalent weight of 100 to 2 000 g/mol, wherein a molar ratio of all of the compounds (a) to all of the compounds (b) used in the reaction is from 2.3/0.7 to 1.7/1.6 and the reaction product possesses a number-average molecular weight of 500 to 15 000 g/mol, an acid number of less than 10 mg KOH/g, and a hydroxyl number of 25 to 250 mg KOH/g.

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

13. The method as claimed in claim 12, wherein the substrate is a metallic substrate coated with a cured electrocoat film, and all of the films applied to the electrocoat film are cured jointly.

14. A multicoat paint system produced by the method as claimed in claim 12.

15. A method of improving stability of paint, the method comprising: adding a reaction product according to claim 11 to a paint that comprises a pigment and a basecoat material.

Description

EXAMPLES

(1) Specification of Particular Components and Measurement Methods

(2) Polyester 1 (P1):

(3) Prepared in accordance with example D, column 16, lines 37 to 59 of DE 4009858 A, using butyl glycol instead of butanol as organic solvent, the solvents present thus being butyl glycol and water. The corresponding dispersion of the polyester has a solids content of 60 wt %.

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

(5) The number-average molecular weight was determined by means of vapor pressure osmosis. Measurement was effected using a vapor pressure osmometer (model 10.00 from Knauer) on concentration series of the component under investigation in toluene at 50 C., with benzophenone as calibration substance for determination of the experimental calibration constant of the instrument employed (in accordance with E. Schrder, G. Mller, K.-F. Arndt, Leitfaden der Polymer-charakterisierung [Introduction to polymer characterization], Akademie-Verlag, Berlin, pp. 47-54, 1982, in which, though, benzil was used as calibration substance).

(6) Determination of the Hydroxyl Number:

(7) The hydroxyl number was determined by the method of R.-P. Krger, R. Gnauck, and R. Algeier, Plaste and Kautschuk, 20, 274 (1982) by means of acetic anhydride in the presence of 4-dimethylaminopyridine as catalyst in a tetrahydrofuran (THF)/dimethylformamide (DMF) solution at room temperature (20 C.), the remaining excess of acetic anhydride following acetylation being fully hydrolyzed and the acetic acid being back-titrated potentiometrically with alcoholic potassium hydroxide solution. Acetylation times of 60 minutes were sufficient in all cases to guarantee complete conversion.

(8) Determination of the Acid Number:

(9) The acid number was determined by the method of DIN EN ISO 2114 in homogeneous solution composed of THF/water (9 parts by volume THF and 1 part by volume distilled water) with ethanolic potassium hydroxide solution.

(10) Determination of the Epoxide Equivalent Weight:

(11) The determination took place in accordance with DIN EN ISO 3001.

(12) Determination of the Solids Content:

(13) The determination took place in accordance with DIN EN ISO 3251 at 130 C., 60 minutes, initial mass 1.0 g.

(14) Production of Inventive Reaction Products (IR):

(15) IR1:

(16) In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer, and condenser, 810.0 g of polytetrahydrofuran diglycidyl ether (Grilonit F 713, from Ems Chemie) with an epoxide equivalent weight of 405 g/eq and 1100 g of dimer diol (Pripol 2033, from Croda) with a hydroxyl number of 204 mg KOH/g (2.0 mol) were introduced without solvent and heated to 125 C. The epoxide equivalent weight of a sample taken therefrom was determined by DIN EN ISO 3001 to be 955 g/mol. When 125 C. was reached, 5.4 g of N,N-dimethylbenzylamine (from BASF SE) were added and the batch was held at 125 C. for 12 hours until epoxide groups were no longer detectable. Cooling gave, at room temperature, a viscous resin.

(17) Number-average molecular weight (resin): 1804 g/mol

(18) Solids content: 99.9%

(19) Epoxide equivalent weight in g/mol: infinite

(20) Acid number: 0.0 mg KOH/g

(21) Hydroxyl number: 118 mg KOH/g solids content

(22) Viscosity (original): 602 mPas,

(23) (measured at 23 C. using a rotational viscometer from Brookfield, model CAP 2000+, spindle 3, shear rate: 5000 s-1).

(24) IR2:

(25) In a 4 l stainless steel reactor equipped with anchor stirrer, thermometer and condenser, 810.0 g of polytetrahydrofuran diglycidyl ether (Grilonit F 713, from Ems Chemie) with an epoxide equivalent weight of 405 g/eq and 524.8 g of dodecylphenol (Dodecylphenol T, from Sasol) with a hydroxyl number of 214 mg KOH/g (2.0 mol) were introduced without solvent and heated to 125 C. The epoxide equivalent weight of a sample taken therefrom was determined by DIN EN ISO 3001 to be 669 g/mol. When 125 C. was reached, 5.4 g of N,N-dimethylbenzylamine (from BASF SE) were added and the batch was held at 125 C. for 12 hours until epoxide groups were no longer detectable. Cooling gave, at room temperature, a viscous resin.

(26) Number-average molecular weight (resin): 1300 g/mol

(27) Solids content: 99.8%

(28) Epoxide equivalent weight in g/mol: infinite

(29) Acid number: 0.0 mg KOH/g

(30) Hydroxyl number: 84 mg KOH/g solids content

(31) Viscosity (original): 750 mPas,

(32) (measured at 23 C. using a rotational viscometer from Brookfield, model CAP 2000+, spindle 3, shear rate: 5000 s.sup.1).

(33) Production of Aqueous Basecoat Materials

(34) Production of a Silver Comparative Waterborne Basecoat 1 (C1)

(35) 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 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-1 as measured with a rotary viscometer (Rheomat RM 180 instrument from Mettler-Toledo) at 23 C.

(36) TABLE-US-00001 TABLE A Parts by Component weight Aqueous phase 3% NaMg phyllosilicate solution 26 Deionized water 13.6 Butyl glycol 2.8 Polyurethane-modified polyacrylate; 4.5 prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A 50% strength by weight solution of 0.6 Rheovis PU 1250 (BASF), rheological agent P1 3.2 TMDD (BASF) 0.3 melamine-formaldehyde resin (Cymel 203 4.1 from Cytec) 10% dimethylethanolamine in water 0.3 polyurethane-based graft copolymer; 20.4 prepared as per page 19, line 44 to page 20, line 21 of DE 19948004 A, solids content adjusted to 32.5 wt % with deionized water TMDD (BASF) 1.6 3% strength by weight aqueous Rheovis AS 3.9 S130 solution; rheological agent, available from BASF Organic phase Mixture of two commercial aluminum 6.2 pigments, available from Altana-Eckart Butyl glycol 7.5 P1 5
Production of Inventive Waterborne Basecoat Materials 1 and 2 (I1 and I2)

(37) To produce the inventive waterborne basecoat material I1, a paint was produced as for the production of the comparative waterborne basecoat material 1 (C1), using IR1, instead of the polyester P1, both in the aqueous phase and in the organic phase. IR1 here was used in 100% form (based on solids content). Based on the solids fraction (nonvolatile fraction), the amount of IR1 used in I1 was the same as that of the polyester P1 used in C1. The different amounts of butyl glycol arising from the different solid contents of IR1 and of dispersion P1 were compensated in the formulation I1 by corresponding addition of butyl glycol. For the production of the waterborne basecoat material I2, the procedure was the same for I1, with the reaction product IR2 being used instead of IR1.

(38) Table 1 shows again the polyesters and reaction products, and their proportions (based on the total amount of the waterborne basecoat materials), used in waterborne basecoat materials (WBM) C1 and I1 and I2, as an overview.

(39) TABLE-US-00002 TABLE 1 Compositions of WBM C1 and I1 to I2 WBM [% by wt.] Reaction product C1 4.92 P1 I1 4.92 IR1 I2 4.92 IR2
Comparison Between Waterborne Basecoat Materials C1 and I1 and I2

(40) To determine the pinholing limit and pinhole count, multicoat paint systems were produced by the following general method:

(41) A cathodically electrocoated steel sheet of dimensions 3050 cm was provided with an adhesive strip on one longitudinal edge, in order to be able to determine the film thickness differences after the coating. The particular waterborne basecoat material was applied electrostatically in wedge format. The resulting waterborne basecoat film was flashed off at room temperature for four minutes and subsequently intermediately dried in a forced air oven at 70 C. for 10 minutes. A customary two-component clearcoat material was applied electrostatically in a film thickness of 35 micrometers to the dried waterborne basecoat film. The resulting clearcoat film was flashed off at room temperature for 20 minutes. The waterborne basecoat film and the clearcoat film were then cured in a forced air oven at 140 C. for 20 minutes. Following visual evaluation of the pinholes in the resulting wedge-shaped multicoat paint system, the film thickness of the pinholing limit and the number of pinholes above this film thickness (in other words, the total number of pinholes on the painted sheet) were ascertained. The results can be found in table 2.

(42) TABLE-US-00003 TABLE 2 Pinholing limit and pinhole count of multicoat paint systems produced using waterborne basecoat materials C1 and I1 and I2 WBM Pinholing limit (micrometers) Pinhole count C1 22 25 I1 28 2 I2 26 5

(43) The results emphasize the fact that the use of the reaction products of the invention or of the waterborne basecoat materials of the invention significantly increases the pinholing limit by comparison with the comparative waterborne basecoat material C1, and at the same time reduces the pinhole count.

(44) Production of a Silver Comparative Waterborne Basecoat Material 2 (C2)

(45) The components listed under aqueous phase in table B 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 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 as measured with a rotary viscometer (Rheomat RM 180 instrument from Mettler-Toledo) at 23 C.

(46) TABLE-US-00004 TABLE B Parts by Component weight Aqueous phase 3% NaMg phyllosilicate solution 26 Deionized water 21.7 Butyl glycol 2.8 Polyurethane-modified polyacrylate; 4.5 prepared as per page 7, line 55 to page 8, line 23 of DE 4437535 A 50% strength by weight solution of 0.6 Rheovis PU 1250 (BASF), rheological agent P1 13.3 TMDD (BASF) 0.3 Melamine-formaldehyde resin (Cymel 203 4.1 from Cytec) 10% dimethylethanolamine in water 0.3 polyurethane-based graft copolymer; 1.8 prepared as per page 19, line 44 to page 20, line 21 of DE 19948004 A, solids content adjusted to 32.5 wt % with deionized water TMDD (BASF) 1.6 3% strength by weight aqueous Rheovis 3.9 AS S130 solution; rheological agent, available from BASF Organic phase Mixture of two commercial aluminum 6.2 pigments, available from Altana-Eckart Butyl glycol 7.5 P1 5
Preparation of an Inventive Waterborne Basecoat Material 3 (I3)

(47) In the same way as for the preparation of I1 and I2, an inventive basecoat material I3 (containing IR1) was produced on the basis of the comparative basecoat material C2 (table B) with replacement of the polyester dispersion P1. Compensation for the different solids contents in relation to the polyester dispersion P1 took place again by corresponding addition of butyl glycol.

(48) TABLE-US-00005 TABLE 3 Compositions of WBM C2 and I3 WBM [% by wt.] Reaction product C2 10.98 P1 I3 10.98 IR1
Comparison Between Waterborne Basecoat Materials C2 and I3

(49) As above for the multicoat paint systems produced using waterborne basecoat materials C1 and I1 to I2, multicoat paint systems were produced using aqueous basecoat materials C2 and I3. The evaluation in terms of pinholing limit and pinhole count also took place in the same way. The results can be found in table 4.

(50) TABLE-US-00006 TABLE 4 Pinholing limit and pinhole count of multicoat paint systems produced using waterborne basecoat materials C2 and I3 WBM Pinholing limit (micrometers) Pinhole count C2 14 63 I3 27 9

(51) The results again emphasize the fact that the use of the reaction products of the invention or of the waterborne basecoat materials of the invention significantly increases the pinholing limit by comparison with the comparative waterborne basecoat material C2, and at the same time reduces the pinhole count.