Aqueous coating composition and production of multicoat paint systems using said coating composition

• US 10,344,181 B2
• Filed: 11/18/2014
• Issued: 07/09/2019
• Est. Priority Date: 12/18/2013
• Status: Active Grant

• Current Assignee: BASF Coatings GmbH (BASF SE)
• Original Assignee: BASF Coatings GmbH (BASF SE)
• Inventors: Steinmetz, Bernhard, Jankowski, Peggy, Luhmann, Nadia, Matura, Michael, Reuter, Hardy, Hoffmann, Peter
• Primary Examiner(s): Tschen, Francisco W
• Application Number:
  US15/104,912
• Publication Number:
  US 20160319155A1
• Time in Patent Office: 1,694 Days
• CPC Class Codes: B05D 7/50 Multilayers
• CPC Class Codes: C08F 220/14 Methyl esters , e.g. methyl (meth)acrylate
• CPC Class Codes: C08F 220/18 with acrylic or methacrylic acids
• CPC Class Codes: C08F 220/1804 C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• CPC Class Codes: C08F 220/40 Esters of unsaturated alcohols , e.g. allyl (meth)acrylate
• CPC Class Codes: C08F 290/147 Polyurethanes; Polyureas
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/4233 derived from polymerised higher fatty acids or alcohols
• CPC Class Codes: C08G 18/67 Unsaturated compounds having active hydrogen
• CPC Class Codes: C08G 18/675 Low-molecular-weight compounds
• CPC Class Codes: C08G 18/755 and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate
• CPC Class Codes: C09D 151/08 grafted on to macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09D 175/14 Polyurethanes having carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds

Abstract

The present invention relates to an aqueous coating composition comprising at least one aqueous dispersion comprising at least one copolymer (CP), said copolymer (CP) being preparable by (i) initially charging an aqueous dispersion of at least one polyurethane, and then (ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane from (i), in which (a) a water-soluble initiator is used, (b) the olefinically unsaturated monomers are metered in such that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time, and (c) the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer and at least one linear hydroxy-functional reaction product (R) having an acid number less than 20 mg KOH/g, the preparation of which involves using at least one compound (v) containing two functional groups (v.a) and an aliphatic or araliphatic hydrocarbyl radical (v.b) which is arranged between the functional groups and has 12 to 70 carbon atoms. The present invention also relates to a method for producing a multicoat paint system using the coating composition, and to the multicoat coating thus produced.

Claims

1. An aqueous coating composition, comprising:

at least one aqueous dispersion comprising at least one copolymer (CP), said copolymer (CP) prepared by

(i) initially charging an aqueous dispersion of at least one polyurethane, and then

(ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane from (i),

in which

(a) a water-soluble initiator is used,

(b) the olefinically unsaturated monomers are metered in such that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time, and

(c) the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer;

and

at least one linear hydroxy-functional reaction product (R) having an acid number less than 20 mg KOH/g, the preparation of which involves using at least one compound (v) containing two functional groups (v.a) and an aliphatic or araliphatic hydrocarbyl radical (v.b) which is arranged between the functional groups and has 12 to 70 carbon atoms,

wherein the at least one copolymer (CP) has a core-shell structure comprising a core comprising the at least one polyurethane and a shell comprising at least one polymer of olefinically unsaturated monomers.

2. The coating composition as claimed in claim 1, wherein the mixture of olefinically unsaturated monomers used in step (ii) comprises 0.1 to 6.0 mol % of polyolefinically unsaturated monomers.

3. The coating composition as claimed in claim 1, wherein the mixture of olefinically unsaturated monomers used in step (ii) comprises allyl methacrylate, and no further polyolefinically unsaturated monomers are present.

4. The coating composition as claimed in claim 1, wherein the olefinically unsaturated monomers in step (ii) (b) are metered in such that a concentration of 4.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time.

5. The coating composition as claimed in claim 1, wherein the functional groups (v.a) in the at least one compound (v) are selected from the group consisting of hydroxyl groups and carboxyl groups.

6. The coating composition as claimed in claim 1, wherein a dimeric fatty acid, a dimer diol, or both, are used as the compound (v) in the preparation of the reaction product (R).

7. The coating composition as claimed in claim 1, wherein the reaction product (R) is prepared by reacting a dimer fatty acid with an aliphatic, araliphatic and/or aromatic dihydroxy-functional compound having a number-average molecular weight of 120 to 6000 g/mol.

8. The coating composition as claimed in claim 7, wherein the aliphatic, araliphatic and/or aromatic dihydroxy-functional compound is at least one of a polyether diol, a, polyester diol and a dimer diol.

9. The coating composition as claimed in claim 1, wherein the at least one reaction product (R) is selected from the group consisting of

a reaction product prepared by reacting a dimer fatty acid with at least one aliphatic dihydroxy-functional compound of the general structural formula (I):

10. The coating composition as claimed in claim 1, wherein at least one hydroxy-functional polymer other than (CP) and (R) as a binder, selected from the group consisting of a polyurethane, a polyester, a polyacrylate and copolymers thereof is additionally present, as is a melamine resin as a crosslinking agent.

12. The coating composition as claimed in claim 1, wherein the olefinically unsaturated monomers are metered in such that a concentration of 5.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time.

13. The coating composition as claimed in claim 1, wherein the olefinically unsaturated monomers are metered in such that a concentration of 4.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time.

14. The coating composition as claimed in claim 1, wherein the olefinically unsaturated monomers are metered in such that a concentration of 3.5% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time.

15. The coating composition as claimed in claim 14, wherein the olefinically unsaturated monomers are metered in such that a concentration range of 0.05 to 3.5% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is used over the entire reaction time.

16. A method for producing multicoat paint systems, the comprising:

(1) applying an 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 the aqueous basecoat material used in stage (1) is a coating composition as claimed in claim 1.

17. The method as claimed in claim 16, wherein the substrate used is a metallic substrate or a plastics substrate, said substrate being untreated or having been pretreated or precoated.

18. A multicoat paint system produced by a method as claimed in claim 16.

19. A method for improving the impact resistance of multicoat paint systems, the method comprising:

applying the coating composition of claim 1 to a substrate; and

then

forming a polymer basecoat film from the coating composition, before applying at least one additional layer to the polymer basecoat film.

11. The coating composition as claimed in claim wherein at least one color pigment, effect pigment, or both, is additionally present.