A RMA CROSSLINKABLE COMPOSITION WITH IMPROVED ADHESION

1 . A crosslinkable composition which crosslinkable by real Michael addition (RMA) reaction comprising

a) a reactive component A with at least two acidic protons C—H in activated methylene or methine groups,

b) a reactive component B with at least two activated unsaturated C═C groups and

c) a catalyst C for catalyzing the RMA crosslinking reaction between components A and B,

d) an adhesion promotor P being a functional alkoxysilane comprising one or more alkoxysilane groups —Si(OR) 4−m where m is 1, 2 or 3 and R is methyl, ethyl, propyl, isopropyl, butyl or isobutyl, connected to a functional moiety comprising one or more functional groups X or a precursor thereof, which is a functional group reactable with component A or component B

wherein said RMA crosslinkable composition is in the form of a kit of parts comprising:

at least one part comprising catalyst C but not both A and B and preferably no A or B, and

at least one part not comprising catalyst C and comprising other components A, B,

wherein one or more of the parts of the kit are an adhesion promotion pre-mix comprising one or more of the adhesion promotors P admixed with one or more of the components A, B, C of the RMA crosslinkable composition, which pre-mix is free of water and pigments.

2 . The crosslinkable composition of claim 1 wherein adhesion promotor P is a functional alkoxysilane with the general formula (X(CH 2 ) n ) m Si(OR) 4−m , where m is 1, 2 or 3; n is 1-20, R is methyl, ethyl, propyl, isopropyl, butyl or isobutyl and X is a functional group reactable with component A or component B or a precursor thereof.

3 . The crosslinkable composition of claim 1 or a wherein the adhesion promotion pre-mix further comprises a water scavenger.

4 . The crosslinkable composition of claim 1 wherein in the adhesion promotion pre-mix the functional alkoxysilane adhesion promotor P is admixed either with the catalyst C or with an organic solvent T or combinations thereof.

5 . The crosslinkable composition of claim 1 wherein the RMA crosslinkable composition comprises a crosslinkable component with component A being predominantly a malonate or an acetoacetate, and a crosslinkable component with component B being an acryloyl and the one or more functional groups X are reactable with malonate or acetoacetate and/or with the acryloyl.

6 . The crosslinkable composition of claim 1 wherein the functional group X reactable with component A or component B is a primary or secondary amine, a thiol, isocyanate, epoxy or a RMA reactable component A′ or B′ which are same or different from the reactive components A and/or B in the RMA crosslinkable components.

7 . The crosslinkable composition of claim 1 wherein one or more functional groups X are a polyfunctional reactive component B′ reactive with a crosslinkable component with reactive component A, wherein the crosslinkable composition is a reaction product of the functional alkoxysilane adhesion promotor with a reactive component B′, said reaction product comprising one or more reactive component B′ as functional groups X.

8 . (canceled)

9 . The crosslinkable composition of claim 1 wherein one or more functional groups X are a polyfunctional reactive component A′ reactive with a crosslinkable component with reactive component B, wherein the crosslinkable composition is a reaction product of the functional alkoxysilane adhesion promotor with a reactive component A′, said reaction product comprising one or more reactive component A′ as functional groups X.

10 . (canceled)

11 . (canceled)

12 . The crosslinkable composition of claim 1 wherein the weight amount of adhesion promotor P, in case of an adduct of an adhesion promotor P with said reactive components A′ or B′ not including the weight of reactive components A′ or B′, is between 0.1 and 10 wt % relative to the total weight of the crosslinkable components.

13 . The crosslinkable composition according to claim 1 wherein the molar ratio of C═C to C═C reactive groups, including C—H in reactive component A, functional groups X in adhesion promotor P and groups X—H in D is between 0.3. and 3.

14 . The crosslinkable composition of claim 1 further comprising reactivity moderator component D being an X—H group containing component D that is also a Michael addition donor reactable with component B under the action of catalyst C, wherein X is N, P, S or wherein X is C as part of an acidic methyl (CH 3 ) group, wherein component A is predominantly a malonate or acetoacetate and wherein the X—H group of component D has a higher acidity than the C—H groups in component A, being characterized in that component D has a pKa (defined in aqueous environment) of at least one unit less than that of the C—H groups in component A.

15 . The crosslinkable composition of claim 1 comprising latent base catalyst C.

16 . (canceled)

17 . A method for applying a RMA crosslinked coating with improved adhesion on a substrate surface comprising

a) Providing the a kit of parts of the RMA crosslinkable composition according to claim 1

b) Preparing a RMA crosslinkable composition by mixing all parts of the RMA crosslinkable composition,

c) applying the RMA crosslinkable composition on the substrate surface, and

d) curing the RMA crosslinkable composition.

18 . The method of claim 17 wherein the RMA crosslinkable composition is applied by spraying and wherein the adhesion promotion pre-mix comprises functional alkoxysilane adhesion promotor P dissolved in organic solvent and is added to the remaining parts of the RMA crosslinkable composition just before spraying to dilute the composition to a spraying viscosity.

19 . The method of claim 17 wherein the substrate is metal.

20 . The method of claims 19 for improving adhesion direct to metal, wherein the metal surface may be chemically treated and modified but not coated with a primer layer comprising a polymer binder.

21 . An adhesion promotion pre-mix for use in the RMA crosslinkable composition of claim 1 which pre-mix is free of water and pigments and comprises

adhesion promotor P being a functional alkoxysilane comprising one or more alkoxysilane groups —Si(OR) 4−m where m is 1, 2 or 3 and R is methyl, ethyl, propyl, isopropyl, butyl or isobutyl, connected to a functional moiety comprising one or more functional groups X, which is a functional group reactable with component A or component B, or a precursor thereof

further comprising one or more components of the RMA crosslinkable composition selected from c)-g)

c) a reactive component A with at least two acidic protons C—H in activated methylene or methine groups,

d) a reactive component B with at least two activated unsaturated C═C groups and

e) a catalyst C for catalyzing the RMA crosslinking reaction between components A and B, but not in combination with both components A and B,

f) reactivity moderator D,

g) organic solvent T.

22 . The adhesion promotion pre-mix of claim 21 comprising adhesion promotor P, substantially no components A and B, base catalyst C and organic solvent T, wherein catalyst C is a carbondioxide blocked strong base catalyst and T is an alcohol.

23 . An adhesion promotor for improving adhesion of a RMA crosslinkable composition comprising crosslinkable components comprising reactive component A with at least two acidic protons C—H in activated methylene or methine groups (the RMA donor group), and crosslinkable components comprising reactive component B with at least two activated unsaturated groups (the RMA acceptor group), and a catalyst C, capable of activating the RMA reaction between reactive component A and B,

said adhesion promotor being a functional alkoxysilane comprising one or more alkoxysilane groups —Si(OR) 4−m where m is 1, 2 or 3 and R is methyl, ethyl, propyl, isopropyl, butyl or isobutyl, connected to a functional moiety comprising one or more functional groups X and X is a reactive component B′ reactable with component A or a component A′ reactable with component B wherein reactable component A′ or B′ are same or different from the reactive components A and/or B of the RMA crosslinkable components.

24 . The adhesion promotor of claim 23 being a reaction product of the functional alkoxysilane wherein functional group X is an amine and a polyfunctional acetoacetate, said reaction product comprising acetoacetate group as functional groups X bonded over an enamine bond to the functional alkoxysilane.

25 . (canceled)

26 . The adhesion promotor of claim 23 being a reaction product of the functional alkoxysilane wherein functional group X is an amine and a polyfunctional reactive component B′, in particular a tri- or tetraacrylate, said reaction product comprising component B′ as functional groups X bonded by Michael addition to the functional alkoxysilane.