Polyether-based reaction products and aqueous basecoat materials comprising said products
The present invention relates to a pigmented aqueous basecoat material comprising a polyether-based reaction product which is preparable by reaction of (a) at least one diisocyanate of the formula (I) OCN—Y—NCO (I) in which Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having from 6 to 30 carbon atoms, with (b) at least one polyether of the general structural formula (II) in which R is a C 3 to C 6 alkylene radical and n is selected accordingly such that the polyether (b) possesses a number-average molecular weight of 200 to 4000 g/mol, where components (a) and (b) 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 a number-average molecular weight of 500 to 15 000 g/mol and an isocyanate content of less than 0.2%.
1. A pigmented aqueous basecoat material, comprising:
a polyether-based reaction product which is prepared by a reaction of
(a) at least one diisocyanate of the formula (I)
OCN—Y—NCO (I)
in which
Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having from 6 to 30 carbon atoms,
with
(b) at least one polyether of the general structural formula (II)
in which
R is a C 3 to C 6 alkylene radical and n is selected accordingly such that the polyether (b) possesses a number-average molecular weight of 200 to 4 000 g/mol,
wherein components (a) and (b) 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 a number-average molecular weight of 500 to 15 000 g/mol and an isocyanate content of less than 0.2%.
2. The pigmented aqueous basecoat material as claimed in claim 1 , wherein the polyether (b) possesses a number-average molecular weight of 800) to 3 200 g/mol.
3. The pigmented aqueous basecoat material as claimed in claim 1 , wherein the group R in the general structural formula (II) comprises tetramethylene radicals.
4. The pigmented aqueous basecoat material as claimed in claim 1 , wherein components (a) and (b) are used in a molar ratio of 0.9/2.1 to 1.5/1.8.
5. The pigmented aqueous basecoat material as claimed in claim 1 , wherein the polyether-based reaction product possesses a number-average molecular weight of 1 250 to 5 000 g/mol.
6. The pigmented aqueous basecoat material as claimed in claim 1 , wherein the divalent radical Y is an aromatic or araliphatic radical.
7. The pigmented aqueous basecoat material as claimed in claim 1 , wherein the divalent radical Y is a saturated aliphatic radical.
8. The pigmented aqueous basecoat material as claimed in claim 6 , wherein the divalent radical Y has from 6 to 15 carbon atoms.
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 polyether-based 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 method for producing a multicoat paint system, the method comprising:
(1) applying a pigmented aqueous basecoat material to a substrate,
(2) forming a polymer film from the coating material applied in stage (1),
(3) applying a clearcoat material to the resulting basecoat film, and then
(4) curing the basecoat film together with the clearcoat film,
wherein a pigmented aqueous basecoat material as claimed in claim 1 is used in stage (1).
12. The method as claimed in claim 11 , 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.
13. A multicoat paint system produced by the method as claimed in claim 11 .
14. A method of improving stability of paint, the method comprising:
adding a polyether-based reaction product to a paint that comprises a basecoat material, wherein
the polyether-based reaction product is obtained by reaction of:
(a) at least one diisocyanate of the formula (I)
OCN—Y—NCO (I)
in which
Y is a divalent aliphatic, aromatic or araliphatic hydrocarbon radical having from 6 to 30 carbon atoms,
with
(b) at least one polyether of the general structural formula (II)
in which
R is a C 3 to C 6 alkylene radical and n is selected accordingly such that the polyether (b) possesses a number-average molecular weight of 200 to 4 000 g/mol,
wherein components (a) and (b) 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 a number-average molecular weight of 500 to 15 000 g/mol and an isocyanate content of less than 0.2%.