PROCESS FOR PRODUCING A MULTILAYER COATING

1 . A process for the multilayer coating of substrates comprising the steps:

1. Applying a filler layer of a filler coating composition onto an optionally pre-coated substrate,

2. Applying a base coat layer of a water-based base coat coating composition containing color-imparting and/or special effect-imparting pigments onto the filler layer,

3. Applying a clear coat layer of a transparent clear coat coating composition onto the base coat layer and

4. Curing the clear coat layer,

wherein the filler coating composition being an organic solvent-based coating composition comprising:

A) at least one binder with functional groups containing active hydrogen,

B) at least one polyisocyanate cross-linking agent with free isocyanate groups and

C) at least one epoxy-functional silane of the general Formula (I):

X denoting the residues

with m being 1-4, or epoxy cyclohexyl,

R1, R2, R3 mutually independently meaning identical or different organic residues with 1 to 30 carbon atoms per molecule, providing that at least one of the residues is an alkoxy group with 1 to 4 carbon atoms and

n is 2, 3 or 4.

2 . A process for the multilayer coating of substrates comprising the following steps:

1. Applying a filler layer of a filler coating composition onto an optionally pre-coated substrate,

2. Applying a single-stage top coat layer of a water-based single-stage top coat coating composition containing color-imparting and/or special effect-imparting pigments onto the filler layer,

3. Curing the single-stage top coat layer, optionally together with the filler layer,

wherein the filler coating composition being an organic solvent-based coating composition comprising:

A) at least one binder with functional groups containing active hydrogen,

B) at least one polyisocyanate cross-linking agent with free isocyanate groups and

C) at least one epoxy-functional silane of the general Formula (I):

X denoting the residues

with m being 1-4, or epoxy cyclohexyl,

R1, R2, R3 mutually independently meaning identical or different organic residues with 1 to 30 carbon atoms per molecule, providing that at least one of the residues is an alkoxy group with 1 to 4 carbon atoms and

n is 2, 3 or 4.

3 . The process according to claim 1 or 2 , wherein the filler coating composition comprises 0.5 to 7.0% by weight solids of the epoxy-functional silane component C), relative to the sum of the solids content of component A) and component B).

4 . The process according to claim 3 , wherein the filler coating composition comprises 1.0 to 6.0% by weight solids of the epoxy-functional silane component C), relative to the sum of the solids content of component A) and component B).

5 . The process according to any one of claims 1 to 4 , wherein n is 2 or 3.

6 . The process according to any one of claims 1 to 5 , wherein R1, R2 and R3 mutually independently mean identical or different alkoxy groups having 1-4 carbon atoms.

7 . The process according to any one of claims 1 to 6 , wherein the binder A) comprises at least one hydroxy-functional (meth)acrylic copolymer.

8 . The process according to any one of claims 1 and 2 to 7 , wherein the clear coat coating composition comprises at least one hydroxy-functional (meth)acrylic copolymer in combination with at least one hydroxy-functional oligoester.

9 . The process according to any one of claims 1 to 8 , wherein the water-based base coat coating composition or the water-based base single-stage top coat coating composition is applied onto the filler layer after curing the filler layer.

10 . The process according to any one of claims 1 to 9 , wherein the substrate comprises vehicle bodies or parts thereof.

11 . Use of the process according to any one of claims 1 to 10 in vehicle repair coating.