ADHESION PROMOTOR FOR REAL MICHAEL ADDITION CROSSLINKABLE COMPOSITIONS

Abstract

The invention relates to an adhesion promotor for improving adhesion on a substrate surface of an RMA crosslink able composition comprising one or more crosslinkable components comprising a reactive component A with at least two acidic protons CH in activated methylene or methine groups, a reactive component B with at least two activated unsaturated CC groups, a catalyst C for catalyzing the RMA crosslinking reaction between components A and B, said adhesion promotor P comprising a moiety comprising one or more functional groups X or precursors thereof readable with component A or component B and a moiety comprising one or more functional groups Y or precursors thereof that adsorb or react with the substrate surface not being an alkoxysilane group. The invention also relates to a RMA crosslinkable composition, also in the form of a kit of parts, to a premix for use as a part in the kit of parts.

Claims

1. An adhesion promotor P for improving adhesion on a substrate surface of an RMA crosslinkable coating composition comprising one or more crosslinkable components comprising a reactive component A with at least two acidic protons CH in activated methylene or methine groups, a reactive component B with at least two activated unsaturated CC groups, a catalyst C for catalyzing the RMA crosslinking reaction between components A and B, optionally a reactivity moderator D and optionally an organic solvent T, said adhesion promotor P comprising a moiety comprising one or more functional groups X or precursors thereof reactable with component A or component B and a moiety comprising one or more functional groups Y or precursors thereof that adsorb or react with the substrate surface not being an alkoxysilane group.

2. The adhesion promotor of claim 1 wherein functional group Y adsorbs on the substrate surface and does not react to form a covalent bond.

3. The adhesion promotor of claims 1-2 wherein functional groups X or Y or both are functional groups pending from a molecule or are moieties within a molecule.

4. The adhesion promotor of claims 1-3 wherein the one or more functional groups X are reactable with malonate or acetoacetate and/or with acryloyl for use in a RMA crosslinkable composition comprising a crosslinkable component with component A being predominantly a malonate or an acetoacetate, preferably malonate, and a crosslinkable component with component B being an acryloyl.

5. The adhesion promotor of claims 1-4 wherein the one or more functional groups X reactable with component A or component B of the RMA crosslinkable components are primary or secondary amine, thiol, isocyanate, epoxy, or RMA reactive components A or B, preferably primary or secondary amine, thiol, or RMA reactive components A or B.

6. The adhesion promotor of claim 5 wherein the one or more functional groups X are RMA reactive components A or B which are same or different from the RMA reactive components A and/or B in the crosslinkable components.

7. The adhesion promotor of claims 1-5 wherein one or more of the functional groups X is a moisture deblockable precursor of X.

8. The adhesion promotor of claim 7 wherein the moisture deblockable precursor of functional group X is a moisture deblockable primary or secondary amine, preferably a ketimine, aldimine or oxazolidine.

9. The adhesion promotor of claims 1-8 wherein the one or more functional groups Y are a heterocyclic group, preferably, a nitrogen containing heterocyclic group, or a polar functional group.

10. The adhesion promotor of claim 9 wherein one or more functional groups Y are a heterocyclic group selected from the group of pyridine, imidazole, cyclic amide, pyrrolidone, morpholine, triazole, benzotriazole or cyclic urea.

11. The adhesion promotor of claim 9 wherein one or more functional groups Y are a polar functional group selected from the group of alcohol, diol, triol, amide and urea or substituted urea.

12. The adhesion promotor of claims 1-11 wherein one or more functional groups X are primary or secondary amine, thiol, isocyanate, epoxy, or RMA reactive components A or B, optionally connected to the moiety comprising functional groups Y over a bridging group R, wherein the one or more functional groups Y comprise a heterocyclic functional group or a polar functional group.

13. The adhesion promotor of claims 1-12 wherein one or more functional groups X are a polyfunctional reactive component B and one or more functional groups Y are a heterocyclic functional group or polar functional group.

14. The adhesion promotor of claim 13 being a reaction product of a polyfunctional reactive component B and a heterocyclic functional group, said reaction product comprising one or more reactive component B as functional groups X and one or more heterocyclic functional group as functional group Y.

15. The adhesion promotor of claim 14 being a reaction product of a polyacryloyl, preferably a tri- or tetra-acryloyl with imidazole, triazole or benzotriazole.

16. The adhesion promotor of claims 1-12 wherein one or more functional groups X are a polyfunctional reactive component A and one or more functional groups Y are a heterocyclic functional group or polar functional group.

17. The adhesion promotor of claim 16 being a reaction product of an adhesion promoter P wherein functional group X is an amine and a polyfunctional acetoacetate, said reaction product comprising an acetoacetate group as functional group X bonded over an enamine bond to adhesion promoter P.

18. The adhesion promotor of claim 17 being the reaction product of polyfunctional acetoacetate, preferably trifunctional acetoacetate, with aminomethylpyridine.

19. The adhesion promotor of claims 1-8 comprising one or more precursors of functional groups Y, preferably moisture deblockable precursors, in particular oxazolidines, isocyanate, and ketals, acetal, orthoesters or epoxy as precursors for diols.

20. The adhesion promotor of claims 1-4 being a heterocyclic compound wherein functional group Y and a functional group X are a moiety within the heterocyclic compound and which functional group X is reactive with reactive component B of the crosslinkable components at curing conditions of the RMA coating composition to in-situ form an adhesive component B-Y not being imidazole, triazole or benzotriazole.

21. The use of the adhesion promotors of anyone of claims 1-20 for improving adhesion on a substrate surface of a RMA crosslinkable coating composition comprising one or more crosslinkable components comprising a reactive component A with at least two acidic protons CH in activated methylene or methine groups, a reactive component B with at least two activated unsaturated CC groups, a catalyst C for catalyzing the RMA crosslinking reaction between components A and B, optionally a reactivity moderator D and optionally an organic solvent T, wherein catalyst C preferably is a CO2 blocked catalyst and reactive component A in the crosslinkable component is preferably predominantly malonate.

22. The use of triazoles, benzotriazoles or imidazoles as an adhesion promotor for improving adhesion on a substrate surface of a RMA crosslinkable coating composition.

23. A RMA crosslinkable composition comprising: a. Crosslinkable components comprising reactive component A with at least two acidic protons CH in activated methylene or methine groups (the RMA donor group), preferably predominantly malonate or acetoacetate, b. Crosslinkable components comprising reactive component B with at least two activated unsaturated groups (the RMA acceptor group), preferably predominantly acryloyl or maleate, c. a catalyst C, capable of activating the RMA reaction between reactive component A and B, preferably a carbon dioxide blocked strong base catalyst, d. one or more adhesion promotors of claims 1-20 e. optionally a reactivity moderator component D f. optionally an organic solvent or a mixture of organic solvents, more preferably reactive solvent, g. optionally pigments, h. optionally water, preferably less than 5, 2 or 1 wt % on total composition weight

24. The RMA crosslinkable composition of claim 23 comprising an XH 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.sub.3) group, wherein component A is predominantly a malonate or acetoacetate and wherein the XH group of component D has a higher acidity than the CH 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 CH groups in component A.

25. The RMA crosslinkable composition according to claim 23 or 24 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, preferably 0.2-5, more preferably 0.5-4 and most preferably 1-2 wt %.

26. The RMA crosslinkable composition according to claims 23-25 wherein the molar ratio of CC to CC reactive groups including CH in A, functional groups X in adhesion promotor P and groups XH in D is between 0.3 and 3, preferably 0.5-2 and even more preferably 0.75-1.5.

27. The RMA crosslinkable composition according to claims 23-26 in the form of a kit of parts comprising two or more parts comprising one or more of the components A, B, C and optional components D and T, wherein a. at least one part comprising catalyst C but not both A and B and preferably no A or B, b. at least one part not comprising catalyst C and one or more of components A, B, C or optional components D, T or further coating additives, c. wherein one or more of the parts of the kit comprise one or more of the adhesion promotors P of claims 1-20.

28. A premix for use in the RMA crosslinkable composition according to claims 23-26 comprising catalyst C, substantially no A or B, T and one or more of the adhesion promotors P of claims 1-20, preferably only C, T and P.

29. A method for applying a RMA crosslinked coating with improved adhesion on a substrate surface comprising a. Preparing a RMA crosslinkable composition by mixing shortly before application, preferably within less than 10 hrs or 5 hrs before application, all parts of the kit of parts of claim 27 and optionally further coating additives, b. applying the RMA crosslinkable composition on the substrate surface, which may optionally be provided with a primer layer, and c. curing the RMA crosslinkable composition.

30. The method of claim 29 wherein the substrate is metal.

31. The method of claims 29-30 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.

Description

EXAMPLES

[0058] The following is a description of certain embodiments of the invention, given by way of example only.

[0059] Abbreviations of adhesion promoters used in the examples are given in Table 1:

TABLE-US-00001 TABLE 1 Abbreviations API 1-(3-aminopropyl) imidazole: AMP 3-(aminomethyl)pyridine (=3-picolylamine) MoEA 4-(2-aminoethyl)morpholine: AEPD: aminoethyl-1,3-propanediol

Adhesion Test:

[0060] The results of adhesion stated in the following examples are based on the cross cut adhesion test following the ISO/DIN 2409, ASTM D3359 protocol. The ranking is briefly summarized as follows:

0: The edges of the cuts are completely smooth; none of the squares of the lattice is detached.
1: Detachment of small flakes of the coating at the intersection of the cuts. A cross-cut area not significantly greater than 5% is affected.
2: The coating has flaked along the edges and/or at the intersection of the cuts. A cross-cut area significantly greater than 5%, but not significantly greater than 15% is affected.
3: The coating has flaked along the edges partly or wholly in large ribbons, and/or it has flaked partly or wholly on different parts of the squares. A cross-cut area significantly greater than 15%, but not significantly greater than 35%, is affected.
4: The coating has flaked along the edges of the cuts in large ribbons and/or same squares have detached partly or wholly. A cross-cut area significantly greater than 335%, but not significantly greater than 65% is affected.
5: Any degree of flaking that cannot even be classified by classification 4.

Metal Substrate:

[0061] To test the adhesion of given examples and comparative examples films were applied on two types of metal substrates Gardobond 26S 6800 OC and Gardobond C. Gardobond is a trade name of the German producer Chemetall. Other examples relate to Q-panel Al-46, an aluminium substrate.

Series 1: Examples and Comparative Examples of Heterocyclic Adhesion Promoters.

[0062] In table 2 the results of two types of adhesion promoters are summarized. 1,2,4-Triazole is primarily used as kinetic modifier (also referred to as reactivity moderator D) but it also contributes to adhesion on a steel substrate, in this case Gardobond 26S. The other adhesion promoters of this table all contain a primary amine group. This amino group can react with part of the acryloyl groups of the mentioned formulation. With FTIR it was proven that the reaction of these amines with acryloyl is completed after 24 hours.

General Procedure for Mixing of the Formulations Used for the Comparative Examples:

[0063] A malonate containing polyester as described below (MPE1 in paint A) was mixed with the DiTMPTA and the thinner n-propanol and stirred till a homogenous sample was obtained.

General Procedure for Preparation of Triazole Containing Compositions:

[0064] The malonate polyester, DiTMPTA and n-propanol were transferred to a flask with screw cap. After obtaining a homogenous mixture the desired amount of 1,2,4-triazole was added to the flask. The 1,2,4-triazole was dissolved by gentle heating (15 minutes 60 C.) followed by stirring for a couple of hours at ambient temperature. If not all triazole is dissolved this procedure is repeated till all triazole is dissolved in the composition.

General Procedure for Mixing Formulations with all Other Adhesion Promoters

[0065] The malonate polyester, DiTMPTA and n-propanol were transferred to a flask and mixed. After obtaining a homogeneous mixture the stated amount of adhesion promoter was added. The solutions were then stirred overnight.

[0066] Prior to use all mentioned formulations were activated by adding the stated amount of initiator which is a tetrabutylammonium hydroxide TBAH solution reactively blocked with diethylcarbonate, with a base concentration of 0.928 meq/g solution (see procedure for preparation of initiator solutions). The initiator is also referred to herein as catalyst CAT4.

TABLE-US-00002 Catalyst Component CAT4 Aqueous TBAH 100 (55%) Diethylcarbonate 45.1 n-propanol 181

[0067] We use different layers of tape to create different spacers for the doctor's blade. This results in a variety of cured film thickness, in the examples beneath a range of 50 to 80 microns. Curing is done at 22 C. and a relatively humidity of 45-65%. The adhesion is tested after 24 hours under these conditions.

TABLE-US-00003 TABLE 2 adhesion promotion test with heterocyclic anchor groups Y and triazole comp. example Example 1 2 3 4 5 1 2 Type adhesion MoEA AMP API 1.2.4- 1.2.4- none none promoter triazole triazole Gram MPE1 49.6 34 89 43.5 47 50.8 46.9 gram 21.7 15.9 38.45 17.75 19.2 21.95 25.7 DiTMPTA grams adhesion 1.31 0.94 2.43 0.19 0.625 0 0 promoter gram 6.1 3.6 5.4 4.7 3.5 1.5 1.5 n-propanol Gram CAT4 3.12 2.19 5.59 2.58 2.79 3.5 3.26 initial [CC]/ 2.78 2.93 2.78 2.78 2.78 2.78 3.25 gram solids Adhesion 0 0 0 0 0 5 5 score* (ISO/ DIN2409:2003 *Gardobond 26 S 6800 OC, Cured film thickness: 50-80 m

[0068] It can be seen that the adhesion promotors used provide good adhesion, whereas the comparative examples show poor adhesion.

Series 2: Examples and Comparative Examples of the Adhesion Promoter Aminoethyl-1,3-Propanediol.

[0069] The way of preparation, applying and testing is the same as outlined above. In this study we used two types of steel.

TABLE-US-00004 TABLE 3 results of adhesion promotion test aminoethyl-1,3-propanediol. example comp. Example 6 7 8 3 4 gr. MPE1 41.9 40.8 14.55 50.8 46.9 gr. DiTMPTA 20.5 20.3 7.5 21.95 25.7 gr AEPD 0.86 1.82 0.83 0 0 gr n-propanol 4.5 5.1 1.5 1.5 1.5 gr CAT4 3.13 3.14 1.02 3.5 3.26 initial[CC]/gram solids 3.13 3.14 3.14 2.78 3.25 adhesion (ISO/DIN 2409:2003) On Gardobond 26 S Cured film thickness: 50-60 m 0 0 0 5 5 60-70 m 0 0 0 5 5 On Gardobond C 60-70 m 0 0 0 5 5 70-80 m 0 0 0 5 5 90-110 m 0 0 0 5 5

Paint Preparations

[0070] Paints A was prepared by mixing the components as described in Table 7 below. Paint A is based on a malonate functional resin MPE1 which is a polyester resin which has been trans-esterified with diethylmalonate. This resin is prepared as follows: Into a reactor provided with a distilling column filed with Raschig rings were brought 382 g of neopentyl glycol, 262.8 g of hexahydrophthalic anhydride and 0.2 g of butyl stannoic acid. The mixture was polymerised at 240 C. under nitrogen to an acid value of 0.2 mg KOH/g. The mixture was cooled down to 130 C. and 355 g of diethylmalonate was added. The reaction mixture was heated to 170 C. and ethanol was removed under reduced pressure. Part the resin was modified (MPE1-S) by addition of succinimide as reactivity moderator; when the viscosity at 100 C. reached 0.5 Pa.Math.s the material was cooled down to 140 and 11.2 grams of solid succinimide were added. This mixture was stirred until all succinimide was dissolved. The resins (MPE1 and MPE1S) were further cooled and diluted with butyl acetate to 85% solids, to yield a material with OH value 16 mg KOH/g, GPC Mn 1750, and a malonate equivalent weight of 350 (active CH EQW 175)

[0071] The succinimide containing resin was mixed with same resin not containing the succinimide and 1,2,4 triazole as adhesion promotor.

TABLE-US-00005 TABLE 7 paint A composition Component Paint A MPE1 139.4 MPE1S 192.2 Pigment paste* 565.5 Pre-dissolve: 1,2,4-triazole 4.8 n-propanol 27.0 Subsequently add Miramer M410 0 Methyl propyl ketone 0 Byk 310:315 1:4 2.8 Tinuvin 292 4.6 *mix 32.0% of Miramer M410 (DiTMPTA component B) with 65.1% of Kronos 2310 and 2.9% of Disperbyk 163 and grind until the particle size is smaller than 10 m

Catalyst Preparation Examples

[0072] Catalyst compositions were prepared by mixing components specified in Table 8.

TABLE-US-00006 TABLE 8 Catalyst compositions Component Catalyst 1 Catalyst 4a Aqueous TBAH 100 0 (55%) Methanolic TBAH 1M 0 51.18 Diethylcarbonate 45.1 Dimethylcarbonate 0 8.6 n-propanol 181 0 TBAH is tetrabutyl ammonium hydroxide.

Examples NE2 and NE3; Comparative Example CN1

[0073] Clear coats were formulated as indicated below and properly mixed; the malonated polyester (MPE) as described in example MPE1 was used as RMA donor. Then the given amount 3-picolylamine (3-aminomethylpyridine) was added, upon stirring, left for 15 minutes and then activated by adding catalyst CAT4. After 10 minutes, the samples were spray applied onto Bonder (Gardobond 26S 6800 OC, Chemetall) or Q-panel (Al-46) substrates. The adhesion was tested after 24 hour cure at ambient temperature. The cured film thickness of all samples mentioned in the table was 50 to 60 micron. Adhesion testing was done with the crosscut method, a 5 indicating total loss of adhesion, a 0 a perfect pass.

TABLE-US-00007 Comp code CN1 NE2 NE3 g MPE1 90.0 90.0 90.0 g DTMPTA 36.7 36.7 36.7 g 3-AMP 0.0 2.8 5.7 g butylacetate 6.0 6.0 6.0 g n-propanol 4.0 4.0 4.0 g catalyst C 6.1 6.1 6.1 wt % (o.s.) 3-AMP 0.0% 2.5% 5.0% adhesion rating Q-panel 5 2-3 0 Bonder 5 0 0

[0074] It can be seen that adhesion improvements are evident at both concentration regimes tested.

Preparation of Enamine Adducts EA1 and EA2

[0075] Added to a 100 ml round-bottomed flask were 4.0 g of 3-picolylamine and 14.1 g of TMP triacetoacetate (Lonzamon AATMP), along with a magnetic stirrer. The flask was then placed in a water bath to help keep the reaction at ambient conditions. A thermometer probe was also submerged in the reaction vessel to observe the temperature of the reaction. The contents were left stirring for 7-8 hours before adding 4.0 g of activated 4 molecular sieves to absorb the water produced as part of the equilibrium reaction. The flask was then left overnight and the contents were filtered. The resulting enamine product was analyzed by 1H NMR to verify the final product and validate the method. In a similar way enamine sample 2 was prepared, using 1-hexylamine.

TABLE-US-00008 EA1 EA2 3-picolylamine (g) 4.0 1-hexylamine (g) 3.7 TMPTAA (g) 14.1 14.1 Ethyl Acetate (g) 4.8 4.7 Mol. Sieves (g) 4.0 4.0 Total (g) 26.9 26.6

[0076] Using the enamines prepared in this table, they were added to formulations as shown in the table below, and applied to different substrates to test for their influences on adhesion. The two formulations were sprayed onto both bonder and Q-panel substrates, and tested after 1 day of ambient drying. Coating formulations and adhesion results are given in the table below. They can be compared to comparative example CN1: example PEA1, containing the pyridine group clearly improves adhesion onto bonder and aluminium, whereas the reference enamine EA2 not containing this moiety, does not show this improvement at this concentration level.

TABLE-US-00009 Code CPEA1 PEA1 g MPE1 73.8 73.9 g DTMPTA 30.5 30.5 g EA2 10.1 g EA1 10.3 g butylacetate 6.6 6.6 g n-propanol 10.0 10.0 g CAT4 5.6 5.6 adhesion rating Q-panel Al-46 5 0 Gardobond 26 S 6800 OC 5 0

Preparation of N-(2-Aminoethyl)-Ethyleneurea (AEEU), and its Enamine Adduct (EA3)

[0077] 103.17 g (1 mole) of diethylenetriamine, 90.08 g (1 mole) of dimethylcarbonate and 630.24 g of xylene were charged to a reaction vessel and mixed at room temperature. The reaction vessel was fitted with a thermometer, a heating mantle and a distillation column/separator setup, in order to collect the methanol that is present and will be formed. On the reactor a dropping funnel was placed containing with the catalyst solution composed of 5.61 g (0.05 mole) of potassium tert-butoxide dissolved in 11.22 g methanol. During the complete reaction the reactor was kept under a blanket of nitrogen. The reaction was started by adding the above mentioned catalyst solution.

[0078] A slight exothermic effect was observed which increased the reaction temperature from 19 C. to 38 C. After 55 minutes the reaction temperature was increased to 90 C., and methanol was collected. The temperature of contents of the reactor was gradually increased and maintained at 133 C. till no methanol was liberated. The temperature of contents of the reactor was increased to 148 C. to remove most of the xylene. After cooling to 104 C. the catalyst, was neutralized with an equimolar amount of isononanoic acid. The contents of the reactor was cooled to 40 C. and the reaction product was poured into a separating funnel and washed with iso-octane. The resulting product was a yellowish very viscous wax at room temperature that slowly crystallized over time.

[0079] This product (AEEU) was combined with TMPTAA (TMP triacetoacetate) and ethylacetate as solvent, in a three-necked flask, and heated to 100 C. This was left for approximately 4 hours before being cooled to room temperature and then filtered. Ethylacetate was removed in vacuo.

TABLE-US-00010 EA3 AEEU (g) 5.01 TMPTAA (g) 15.00 ethyl acetate (g) 5.32 mol. sieves (g) 4.0 Total (g) 29.3

[0080] The enamine formed (EA3) was formulated as a clear coating (PEA2), and sprayed onto a Gardobond 26S 6800 OC substrate. Adhesion testing was done after a 4 hr ambient+30 min 80 C drying time, and found to be very good (score 0).

TABLE-US-00011 PEA2 MPE1 (g) 49.27 DTMPTA (g) 20.33 EA3 (g) 6.26 n-propanol (g) 3.70 butyl acetate (g) 4.24 Catalyst CAT4 (g) 6.34 Total (g) 90.14

Preparation of Adduct of 1,2,4-Triazole and DTMPTA (TD1)

[0081] The catalyst used in this synthesis was prepared as follows: a solution of tetrabutylammonium hydroxide in methanol is subjected to a solvent switch, by concentrating in a rotating film evaporator at 35 C. under reduced pressure, after adding propanol. Fresh propanol is added at various moments while removing methanol. The distillation is finished at a residual methanol content=4.5 wt % as confirmed by GC analysis. Next the solution is neutralized by bubbling gaseous CO2 through the liquid via a glass inlet tube at room temperature. The reaction was judged to be finished when a water diluted sample indicates a pH of <8.5; final base content is 1.5 eq/kg solution as determined by potentiometric titration with 0.1 M HCl.

[0082] 230 gram of a 15% 1,2,4-triazole solution in n-propanol (0.217 mole per 100 ml) was mixed at RT with 235 gram of DTMPTA and 5.0 gram of the catalyst solution described above. The reaction mixture was stirred at RT for 4 hours and monitored periodically with FTIR. No significant change in IR spectrum was observed after 3.5 hours reaction time. Then 40 grams of sodium hydrogencarbonate was added to the reaction mixture and stirred for 2 hours. The final product was obtained after filtration of the reaction mixture. After this, the mixture was vacuum distilled until no n-propanol was removed anymore. Acid value determination showed that no (acidic) free 1,2,4-triazole was left in this material. The resulting material contains triazole moieties added by an aza-Michael addition to acryloyl functional groups, as well as unreacted acryloyl groups.

Testing in a Paint Formulation

[0083] A pigment paste was made by milling a mixture of 117.6 g Miramer M4004 (Miwon), 240.5 g Kronos 2310 (Kronos BV), and 9.6 g Disperbyk-2150 (Altana). After finishing 10.1 g butylacetate was added and mixed. A paint was made by mixing the components listed in the below table. Catalyst CAT4 was added and stirred into the mixture in a level of 0.05 meq catalyst per g of total solid resins.

TABLE-US-00012 CompTA TA MPE1 (g) 51.8 44.7 Pigment paste (g) 211.4 234.41 DTMPTA (g) 66.2 33.1 TD1 (g) 0 51.4 TMPtriacetoacetate 2 2 succinimide 0.83 0.92 n-propanol 25.2 28 BYK3550 0.76 0.84 catalyst CAT4 9.1 10 crosshatch adhesion 0% 95%

[0084] A coating was made by spraying the two paints (CompTA and TA) onto Gardobond 26S/60/OC (Chemetall) and curing at RT. Crosshatch adhesion was measured after 7 days. Paint TA containing the adduct TD1 showed good adhesion (95% crosshatch) whereas the reference paint (CompTA) did not (0% crosshatch).

[0085] Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

[0086] Further modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.