THERMALLY CURABLE TWO-COMPONENT COATING COMPOUNDS

Abstract

A two-component coating composition comprising at least one water-dispersible polymer mixture (A) which has at least one mercapto-reactive group selected from the group of epoxide and Michael acceptor, and also at least one water-emulsifiable thiol (B) comprising, as formation components, (Ba) at least one compound having at least two mercapto groups, (Bb) at least one compound having at least one mercapto-reactive group and at least one dispersing group, wherein the formation component (Ba) has a Hansch parameter of at least 2.0.

Claims

1.-15. (canceled)

16. A two-component coating composition comprising at least one water-dispersible polymer mixture (A) which has at least one mercapto-reactive group selected from the group of epoxide and Michael acceptor, and also at least one water-emulsifiable thiol (B) comprising, as formation components, (Ba) at least one compound having at least two mercapto groups, (Bb) at least one compound having at least one mercapto-reactive group and at least one dispersing group, wherein the formation component (Ba) has a Hansch parameter of at least 2.0.

17. The two-component coating composition according to claim 16, wherein the mercapto-reactive group in the water-dispersible polymer mixture (A) is an itaconate, methylenemalonate, maleimide, fumarate, maleate, glycidyl, acrylate, acrylamide, crotonate, cinnamate, methacrylamide and/or methacrylate group.

18. The two-component coating composition according to claim 16, wherein the polymer mixture (A) comprises a polyurethane acrylate, a polyester acrylate, a polyether acrylate, an epoxy acrylate, a multifunctional acrylate monomer or a glycidyl ether-functional epoxy resin.

19. The two-component coating composition according to claim 16, wherein the polymer mixture (A) comprises a polyurethane comprising, as formation components, (Aa) at least one organic aliphatic, aromatic or cycloaliphatic di- or polyisocyanate, (Ab) at least one compound having at least one isocyanate-reactive group and at least one itaconate, methylenemalonate, maleimide, fumarate, maleate, acrylate, acrylamide, crotonate, cinnamate, methacrylamide and/or methacrylate group, (Ac) optionally at least one compound having at least two isocyanate-reactive groups, (Ae) optionally at least one compound having exactly one isocyanate-reactive group, (Ag) at least one compound having at least one isocyanate-reactive group and at least one dispersing group.

20. The two-component coating composition according to claim 16, wherein component (Ba) is esters of polyhydric alcohols with mercaptopropionic acid.

21. The two-component coating composition according to claim 16, wherein component (Ba) is trimethylolpropane tri smercaptopropionate (TMPMP), pentaerythritol tetramercaptopropionate (PETMP), polycaprolactone tetramercaptopropionate (PCL4MP1350) or dipentaerythritol hexamercaptopropionate (DIPETMP).

22. The two-component coating composition according to claim 16, wherein component (Bb) comprises a polyalkylene ether group as dispersing group.

23. The two-component coating composition according to a claim 16, wherein component (Bb) comprises a polyethylene ether group as dispersing group.

24. The two-component coating composition according to claim 23, wherein the polyethylene ether group has a molecular weight Mn of from 200 g/mol to 2200 g/mol.

25. The two-component coating composition according to claim 16, wherein component (Bb) comprises anionic groups or groups that can be converted into anionic groups as dispersing groups.

26. The two-component coating composition according to claim 25, wherein the anionic groups or groups that can be converted into anionic groups are phosph(on)ate, sulf(on)ate and/or carboxylate groups.

27. A process for preparing aqueous dispersions according to claim 16, wherein the polymer mixture (A) and thiol (B) are prepared separately from one another and then mixed with each other.

28. The use of a two-component coating composition according to a claim 16 in coatings and paints.

29. The use of a two-component coating composition according to claim 16 for coating substrates.

30. The use of a two-component coating composition according to claim 16 for coating parts of buildings, coatings on vehicles and aircraft, and industrial applications, railways, utility vehicles in agriculture and construction, what is known as ACE (agricultural construction and earthmoving equipment), wind turbines, bridges, buildings, power masts, tanks, containers, pipelines, power stations, chemical plants, ships, cranes, halls, roofs, furniture, windows, doors, wood flooring, cardboard, for floor coverings, such as in parking levels or in hospitals, automotive paints as refinish applications, and refinish, plastics and industrial applications.

Description

EXAMPLES

1) Synthesis of Water-Emulsifiable Thiols (B)

General Procedure A-1:

[0206] 30.0 g of TMPMP (76.4 mmol) and the respective amounts of modifier are weighed into a 100 ml three-neck flask and mixed by stirring at room temperature. After addition of 0.09 μl of DMPP (0.76 mmol, corresponding to 1.0 mol % based on TMPMP), the reaction mixture is heated to 40° C. and allowed to react for 2 hours up to a conversion of ≥95%.

[0207] Conversion is monitored by .sup.1H NMR spectroscopy in CDCl.sub.3 or d.sub.6-acetone as solvent.

TABLE-US-00003 a) nonionic modification Modifier Mod. polythiol Type Amount TMPMP-1a Bisomer ® MPEG 350 MA 3.29 g (=10 mol %) TMPMP-1b Bisomer ® MPEG 350 MA 4.93 g (=15 mol %) TMPMP-1c Bisomer ® MPEG 350 MA 6.57 g (=20 mol %) TMPMP-2a Bisomer ® MPEG 550 MA 4.80 g (=10 mol %) TMPMP-2b Bisomer ® MPEG 550 MA 7.20 g (=15 mol %) TMPMP-2c Bisomer ® MPEG 550 MA 9.60 g (=20 mol %) TMPMP-3a Bisomer ® S 10 W 16.5 g (=10 mol %) TMPMP-3c Bisomer ® S 10 W 33.0 g (=20 mol %) TMPMP-4a Pluriol ® A 10 R*.sup.) 3.80 g (=10 mol %) *.sup.)Due to the low reactivity of the allyl ether, the reaction mixture had to be heated at 60° C. for 8 hours or at 80° C. for 4.5 hours to achieve sufficient conversion.

TABLE-US-00004 b) anionic modification Modifier Mod. polythiol Type Amount TMPMP-5a Acrylic acid 0.55 g (=10 mol %) TMPMP-6a Methacrylic acid 0.66 g (=10 mol %) TMPMP-7a Sipomer ® β -CEA 1.10 g (=10 mol %) TMPMP-8a Sipomer ® PAM 200**.sup.) 3.71 g (=10 mol %) TMPMP-9a Sipomer ® PAM 4000 1.61 g (=10 mol %) TMPMP-10***.sup.) Methacrylic acid + 0.66 g (=10 mol %) lauryl methacrylate 1.94 g (=10 mol %) **.sup.)Conversion was only around 80%. ***.sup.)For the preparation of TMPMP-10, 3.75 g of PETMP (=10 mol %) were allowed to pre-react with the modifiers mentioned and then 26.3 g of TMPMP were added thereto.

2) Testing of Self-Emulsifying Action

General Procedure A-2:

[0208] The modified TMPMP is mixed with water in a weight ratio of 1:2 and emulsified using an Ultra-Turrax T25; energy was input for 10 seconds at 11 000 revolutions per minute. As a standard initial weight, 3.0 g of modified TMPMP and 6.0 g of demineralized water are weighed into a glass beaker (50 ml) in order to produce the oil-to-water phase ratio described above. For experiments in which the modifier is already present in the form of an aqueous solution, correspondingly less demineralized water needs to be weighed in. In the case of anionically modified polythiols (TMPMP-5a to -10), small amounts of base (sodium hydroxide solution or ammonia) were added to the water in order to deprotonate the acid groups of the modified polythiol; the pH of the aqueous phase is adjusted to the range 8-9. Following the production of the O/W emulsion, a visual check of the sample is conducted at regular intervals for the purpose of monitoring the stability.

Comparative Experiment C-1:

[0209] The procedure is as described in A-2, with the difference that pure, unmodified TMPMP is used instead of the hydrophilically modified TMPMP.

Comparative Experiment C-2:

[0210] The procedure is as described in A-2, with the difference that pure, unmodified TMPMP is used instead of the hydrophilically modified TMPMP. As external emulsifiers, use is made of a mixture of 0.027 g of Dowfax® 2A1 (0.4% by weight based on TMPMP) and 0.090 g of Lutensol® TO 82 (0.6% by weight based on TMPMP).

TABLE-US-00005 TABLE X Stability of various O/W emulsions based on (modified) TMPMP Polythiol Emulsion stability C-1 breaks within a few minutes C-2 breaks within a few minutes TMPMP-1a phase separation after 2 hours TMPMP-1b phase separation after 3½ hours TMPMP-1c phase separation after 4½ hours TMPMP-2a phase separation after 5 hours TMPMP-2b phase separation after 3 hours TMPMP-2c phase separation after 3 hours TMPMP-3a phase separation after 3½ hours TMPMP-3c phase separation after 2½ hours TMPMP-4a phase separation after 3½ hours TMPMP-5a phase separation after 1-2 hours TMPMP-6a phase separation after 1-2 hours TMPMP-7a phase separation after 1-2 hours TMPMP-8a phase separation after 1-2 hours TMPMP-9a phase separation after 1-2 hours TMPMP-10 phase separation after 1-2 hours  O/W emulsions with unmodified TMPMP are not stable even as a result of adding external emulsifiers. Only the use of hydrophilically modified, “self-dispersing” TMPMP results in sufficiently stable O/W emulsions.
3) Compatibility with Water-Dispersible Polymer Mixture (A)

[0211] To the water-dispersible polymer mixtures (A) listed in the table were added equimolar amounts of thiol (B) (O/W emulsion or aqueous solution) and the stability of the blends was tested. The aim of this was to achieve a processing time of 2 hours without visible changes.

TABLE-US-00006 TABLE Y Formulation stability with respect to various reactive resin emulsions ETTMP C-1 C-2 TMPMP-2a 1300 Laromer ® GPTA*) — gels within a stable — few minutes + evolution of heat Laromer ® UA 8949 phase — stable — separation after 5 min Laromer ® UA 9064 — — stable gels within 2 h**.sup.) Laromer ® UA 9095 phase — stable — separation after 5 min EpiRez ® 3510-W-60 coagulate — stable — Waterpoxy ® 1422 coagulate — stable — Waterpoxy ® 1455 coagulate — stable — *)as a 30% aqueous emulsion, stabilized with external emulsifiers (0.4% Dowfax ® 2A1 + 0.6% Lutensol ® TO 82) **.sup.)comparative example 1 from WO 2013/139602  Only blends with the TMPMP emulsions according to the invention are stable. Instabilities are observed for non-hydrophilically modified TMPMP (C-1 and C-2) or water-soluble TMPMP (ETTMP 1330).
4) Performance Testing in Formulation with Aqueous Urethane Acrylate Dispersions

[0212] For investigation of the mechanical-technological properties of such crosslinked polymer films, formulations are produced from the resin and hardener components and are then applied to glass plates as thin films for the determination of the pendulum hardness or are poured out as thick-layer films for determination of the crosslinking density. To this end, the modified Thiocure® TMPMP is emulsified according to the conditions described above and blended with the respective C═C-functional resin component while stirring with an Ultra-Turrax (10 seconds at 11 000 revolutions per minute). Application to the glass plate was effected using the undiluted sample with a wet film thickness of 200 μm. For measurement of the crosslinking action, the blend is diluted to a solids content of 20% by addition of demineralized water, poured into a round mold (inner Ø approx. 6.9 cm) and dried at room temperature for 7 days.

[0213] For comparison purposes, the two radiation-curable urethane acrylate dispersions were also UV-cured; to this end, 2% by weight of Irgacure® 500 as photoinitiator were added to each of them and the resulting polymer films were crosslinked by the action of UV light (total exposure 752 mJ/cm.sup.2, peak radiation intensity 1.39 W/cm.sup.2).

[0214] The pendulum hardness was determined in accordance with DIN standard 53 157 after a drying time of 6 days at room temperature and an additional day at 60° C., the measurement result is given here as the number of pendulum strokes.

[0215] The crosslinking density was determined indirectly via the mass lost by the sample after solvent storage as follows: A piece of polymer film measuring about 2×2 cm and approx. 0.6 mm thick is weighed beforehand (=initial mass m.sub.0) and, placed in 60 ml of methyl ethyl ketone, stored in a 100 ml flask for 24 hours with gentle shaking. The remaining material is then filtered off on a 45 μm filter, re-dried in a drying cabinet at 40° C. for one day and weighed again (=gel content m.sub.T). The percentage gel content of the crosslinked sample is calculated according to (m.sub.0−m.sub.T)/m.sub.0×100%.

[0216] As can be seen from the results summarized in tables Z1 and Z2, the use of the polythiol emulsions according to the invention leads to significant crosslinking of the polymer films based on urethane acrylate dispersions which is of a level comparable to the prior art (=SH-PUD) or to radiation curing. In contrast, such polymer films are less hard and thus more flexible/more elastic, which is manifested in markedly reduced pendulum hardnesses.

TABLE-US-00007 TABLE Z1 Performance properties of selected formulations based on Laromer ® 8949 C-1 Ex. 1A Ex. 1B Ex. 2A Ex. 2B Ex. 3A Ex. 3B C-2a C-2b C-3 Crosslinker without TMPMP-1b TMPMP-2b TMPMP-3a SH-PUD**.sup.) UV light Amount*.sup.) — 21.0 28.0 21.0 28.0 21.0 28.0 39.0 52.0 — Pendulum 40 57 53 56 53 44 51 101 107 86 hardness Gel content 0% 35% 76% 58% 71% 52% 58% 62% 81% 79% *.sup.)In % by weight solid/solid based on the C═C-functional binder **.sup.)Example 2 from WO 2013/139602

TABLE-US-00008 TABLE Z2 Performance properties of selected formulations based on Laromer ® 9095 C-4 Ex. 4A Ex. 4B Ex. 5A Ex. 5B Ex. 6A Ex. 6B C-5a C-5b C-6 Crosslinker without TMPMP-1b TMPMP-2b TMPMP-3a SH-PUD**.sup.) UV light Amount*.sup.) — 27.8 37.0 27.8 37.0 27.8 37.0 51.5 68.7 — Pendulum 15 34 17 23 18 22 12 99 104 98 hardness Gel content 0% 87% 94% 93% 91% 91% 88% 91% 94% 88% *.sup.)In % by weight solid/solid based on the C═C-functional binder **.sup.)Example 2 from WO 2013/139602