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EP-4347710-B1 - MIXER SYSTEM FOR PRODUCING AQUEOUS COATING MATERIALS

EP4347710B1EP 4347710 B1EP4347710 B1EP 4347710B1EP-4347710-B1

Inventors

  • LUECKERT, JENS
  • Foelling, Frederik
  • MACHACZEK, PETER
  • DIEPENBROCK, Vera
  • HOEVELMANN, Claas Henrik
  • SCHNIEDERS, Britta
  • Winsberg, Jan
  • GLOMB, MELANIE
  • FOCKE, THOMAS

Dates

Publication Date
20260513
Application Date
20220517

Claims (18)

  1. A mixer system for producing aqueous coating materials from at least one aqueous pigment paste A, comprising at least one color pigment, and at least one aqueous mixing clear resin component B, whereby the at least one mixing clear resin component B comprises at least one aqueous dispersion (wD) comprising an acrylic-based multi-stage emulsion polymer, whereby the acrylic-based multi-stage emulsion polymer is produced by successive radical emulsion polymerization of at least two mixtures (M) of olefinically unsaturated monomers, wherein the mixture (M) applied in the last step of emulsion polymerization comprises at least one silane-containing olefinically unsaturated monomer.
  2. The mixer system as claimed in claim 1, wherein the pigment paste A comprises at least one anionically stabilized binder (a-2) and/or at least one nonionically stabilized binder (a-3).
  3. The mixer system as claimed in claim 1 or 2, wherein the anionically stabilized binder (a-2) of the pigment paste A is an anionically stabilized polyurethane polymer in dispersion in water, where the anionically stabilized polyurethane polymer has an acid number of 20 to 40 mg KOH/g, based on the solids content, where the dispersion has a pH of 7.0 to 8.0, and where the dispersion comprises a polyol, more particularly polypropylene glycol, having an average molar mass M n of 500 to 1500 Da.
  4. The mixer system as claimed in any of the preceding claims, wherein the nonionically stabilized binder (a-3) of the pigment paste A is a nonionically stabilized acrylate copolymer in dispersion in water, the nonionically stabilized acrylate copolymer being obtainable by reaction of (I) at least one anchor group monomer unit having at least one ionizable functional group, a functional group with active hydrogen, or a combination thereof, where - the ionizable functionality is other than a carboxylic acid group in which the carbonyl carbon is separated from the closest ethylenically unsaturated carbon by at least four atoms, - the anchor group of monomer units (a) contain no polyoxyalkylene groups, and - one of the anchor group monomer units is copolymerized 1-(2-methacryloyloxyethyl)-2-imidazolidinone; (II) 5 wt% to 45 wt%, based on the total weight of the monomers, of at least one monomer unit comprising a polyoxyalkylene group, a gamma-hydroxycarbamate group, a beta-hydroxycarbamate group, and a combination thereof; and (III) 1 to 50 weight percent, based on the total weight of the monomers, of at least one aromatic monomer unit.
  5. The mixer system as claimed in any of the preceding claims, wherein the at least one aqueous mixing clear resin component B further comprises at least one acrylate-based microgel dispersion (b-1), the acrylate-based microgel having a glass transition temperature T g of 50 to 60°C (determined on the basis of DIN 51005 and as further outlined in the description).
  6. The mixer system as claimed in any of the preceding claims, wherein the preparation of the acrylic-based multi-stage emulsion polymer comprised in the aqueous dispersion (wD) encompasses the successive radical emulsion polymerization of three mixtures (MA), (MB), and (MC) of olefinically unsaturated monomers.
  7. The mixer system as claimed in any of the preceding claims, wherein the silane containing olefinically unsaturated monomer comprises, as olefinically unsaturated moiety, a (meth)acrylate function, an allyl group or a vinyl group.
  8. The mixer system as claimed in any of the preceding claims, wherein the silane containing olefinically unsaturated monomer is described by the following general formula (I) [X-SiR 1 a (OR 2 ) 3-a ] (I) wherein X represents a group having an olefinically unsaturated group and being bound to the silicon via a carbon atom, R 1 represents, independently from each other, an alkyl, cycloalkyl, aryl, or aralkyl group, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NR a groups, where R a is alkyl, cycloalkyl, aryl, or aralkyl; R 2 represents hydrogen, an alkyl, or a cycloalkyl group, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur or NR a groups, where R a is alkyl, cycloalkyl, aryl, or aralkyl; a is 0, 1 or 2, preferably 0 or 1, most preferred 0.
  9. The mixer system as claimed in claim 8, wherein R 1 and R 2 are, independently from each other, a C 1 -C 6 alkyl group, preferably a C 1 alkyl group (i.e. methyl).
  10. The mixer system as claimed in any of claims 7 to 9, wherein the amount of silane containing olefinically unsaturated monomer applied in the last step of emulsion polymerization is from 30 to 80 wt%, based on the total amount of monomers of the mixture (M) applied in the last step of emulsion polymerization.
  11. A method for producing an aqueous coating material by mixing at least two aqueous components, wherein a mixer system as claimed in any of claims 1 to 10 is used and wherein at least one pigment paste A and at least one mixing clear resin component B are applied and thus mixed.
  12. Aqueous coating material based on the mixing system according to claims 1 to 10, whereby the aqueous coating material contains, in intermixed form, at least two aqueous components, whereby at least one component is a pigment paste A and at least one further component is a mixing clear resin component B of the mixing system.
  13. A method of producing a coating layer on a substrate comprising the application of an aqueous coating material of claim 12 onto the substrate and subsequent drying of the applied coating material.
  14. The method according to claim 13, wherein the drying step is conducted at a temperature of below 80°C, preferably of below 60°C, more preferably of below 40°C.
  15. The method according to claim 13 or 14, wherein, after application of the coating material according to claim 12, a clearcoat material is applied onto the applied coating material according to claim 12 and wherein both the applied coating material according to claim 12 and the applied clearcoat material are cured together.
  16. The method according to claim 15, wherein a silane-based clearcoat material (i.e. a clearcoat material which cures via hydrolyzation and condensation of hydrolysable silane functions, preferably alkoxysilane functions), is applied as clear coat material.
  17. The method according to any of claims 13 to 16, wherein the substrate is a multilayer coating system having damaged sides, meaning that the method involves the repair of the multilayer coating system.
  18. Multicoat system prepared according to any of claims 13 to 17.

Description

The present invention relates to a mixer system for producing aqueous coating materials from at least one aqueous pigment paste A, comprising at least one color pigment, and at least one mixing clear resin component B, comprising at least one aqueous dispersion (wD), wherein the dispersion (wD) comprises an acrylic-based multi-stage emulsion polymer which is prepared by use of at least one silane-containing olefinically unsaturated monomer. The present invention further relates to a method for producing a beforementioned aqueous coating material in which the individual components A and B are mixed to give the aqueous coating material. The present invention also relates to a process of producing a coating layer on a substrate comprising the application of a beforementioned aqueous coating material to a substrate and subsequent low-bake curing of the applied coating material. The present invention lastly relates to the use of a mixer system of the invention for producing aqueous coating materials for refinishing and/or for the coating of automobile bodies and/or plastics parts. State of the art Polyacrylate dispersions synthesized by emulsion polymerization show high potential in coating applications. Exemplary state of the art dispersions are two or multi-step emulsion polyacrylates with a core-shell or seed-core-shell (SCS) architecture. These acrylic-based multi-stage emulsion polymers are applied as resin/binder components in aqueous coating materials like aqueous basecoats. For example, WO 2017/088988 A1 and WO 2016/116299 A1 describe such acrylic-based multi-stage emulsion polymer and their respective use in aqueous basecoats in the field of automotive coating application. Addressed objectives are, for example, adhesion properties and aesthetic properties like avoidance of pinholes. One major field of interest in automotive coating applications is the low-bake area, i.e. the possibility to cure the applied coating materials at comparably low temperatures without taking a loss in coating performance properties. While the low-bake property is an intrinsic requirement in refinish (i.e. repair) applications, it is also desirable in OEM (original equipment manufacturing) automotive applications for economic and environmental reasons. WO 2021/018594 A1 discloses a mixing system for producing aqueous coating materials with low VOC (volatile organic content) for, in particular, automotive refinish applications. The mixing system comprises at least one aqueous pigment paste and at least one pigment-free component B. The mixing system may comprise, among others, an acrylic-based multi-stage emulsion polymer. The mixing system is suitable for refinishing and/or coating of automobile bodies and/or plastic parts. Also, the mixing system exhibits very good storage stability and high shade accuracy during repair coating, meaning that respective refinish process may be conducted with high accuracy and reproducibility. Even if the above-described prior art coating materials and mixing systems already show quite notable performance profiles, it remains a challenge to improve mechanical properties, like in particular adhesion and interlayer adhesion properties, of respective coating layers and build-ups, especially in the low-bake area. Objective and problem A problem addressed by the present invention, accordingly, was to provide a mixing system for producing aqueous pigment-containing coating materials for refinishing and/or coating of automobile bodies and/or plastic parts, whereby coating layers and build-ups produced by application of these coating materials should exhibit excellent adhesion and interlayer adhesion properties. Technical solution The problems described above are solved by the subject-matter claimed in the claims and also by the preferred embodiments of that subject-matter that are described in the description hereinafter. In particular, it was found that the problems could be solved by means of a mixer system for producing aqueous coating materials from at least one aqueous pigment paste A, comprising at least one color pigment, and at least one aqueous mixing clear resin component B, whereby the at least one mixing clear resin component B comprises at least one aqueous dispersion (wD) comprising an acrylic-based multi-stage emulsion polymer, whereby the acrylic-based multi-stage emulsion polymer is produced by successive radical emulsion polymerization of at least two mixtures (M) of olefinically unsaturated monomers, wherein the mixture (M) applied in the last step of emulsion polymerization comprises at least one silane-containing olefinically unsaturated monomer. A further subject of the present invention is a method for producing a beforementioned aqueous coating material by mixing the at least two aqueous components A and B and optionally with at least one further component C. The present invention relates, moreover, to the use of a mixer system of the invention for producing aqueous coating mat