ALKOXYSILANE-FUNCTIONALIZED ALLOPHANATE-CONTAINING COATING COMPOSITIONS

Abstract

The present invention relates to alkoxysilane-functionalized, allophanate-containing coating compositions, to a process for producing them, and to their use. In particular, the alkoxysilane-functionalized, allophanate-containing coating compositions include a) as a binder component, 10-99 wt % of at least one reaction product of i) at least one monourethane i) containing alkoxysilane groups and of the formula 1

R.sub.n(OR.sup.1).sub.3-nSi—R.sup.2—NH—(C═O)—OR.sup.3  formula 1

where R, R.sup.1, R.sup.2 and R.sup.3 are each independently hydrocarbyl radicals having 1-8 carbon atoms, which may be linear, branched or cyclic, or else may be integrated together to form a cyclic system, and n is 0-2, and ii) at least one diisocyanate ii), in a molar ratio of i) to ii) of from 3:1 to 1.5:1, preferably from 2.5:1 to 1.8:1, particularly preferably 2:1; b) 1-90 wt % of at least one other binder component, different from a), preferably a hydroxyl-containing or amino-containing binder component, c) 0-50 wt % of at least one aromatic, aliphatic or cycloaliphatic polyisocyanate having an NCO functionality of at least 2, preferably 2.8 to 6, d) 0-5 wt % of at least one catalyst, where components a)-d) add up to 100 wt %.

Claims

1. An alkoxysilane-functionalized, allophanate-containing coating compositions comprising a) as a binder component, 10-99 wt % of at least one reaction product of i) at least one monourethane i) containing alkoxysilane groups and of the formula 1
R.sub.n(OR.sup.1).sub.3-nSi—R.sup.2—NH—(C═O)—OR.sup.3  formula 1 where R, R.sup.1, R.sup.2 and R.sup.3 are each independently hydrocarbyl radicals having 1-8 carbon atoms, which may be linear, branched or cyclic, or else may be integrated together to form a cyclic system, and n is 0-2, and ii) at least one diisocyanate ii), in a molar ratio of i) to ii) of from 3:1 to 1.5:1; b) 1-90 wt % of at least one other binder component, different from a), c) 0-50 wt % of at least one aromatic, aliphatic or cycloaliphatic polyisocyanate having an NCO functionality of at least 2, d) 0-5 wt % of at least one catalyst, where components a)-d) add up to 100 wt %, e) optionally auxiliaries and/or additives, f) optionally solvents.

2. An alkoxysilane-functionalized, allophanate-containing coating compositions consisting of a) as a binder component, 10-99 wt % of at least one reaction product of i) at least one monourethane i) containing alkoxysilane groups and of the formula 1
R.sub.n(OR.sup.1).sub.3-nSi—R.sup.2—NH—(C═O)—OR.sup.3  formula 1, where R, R.sup.1, R.sup.2 and R.sup.3 are each independently hydrocarbyl radicals having 1-8 carbon atoms, which may be linear, branched or cyclic, or else may be integrated together to form a cyclic system, and n is 0-2, and ii) at least one diisocyanate ii), in a molar ratio of i) to ii) of from 3:1 to 1.5:1; b) 1-90 wt % of at least one other binder component, different from a), c) 0-50 wt % of at least one aromatic, aliphatic or cycloaliphatic polyisocyanate having an NCO functionality of at least 2, d) 0-5 wt % of at least one catalyst, where components a)-d) add up to 100 wt %, e) optionally auxiliaries and/or additives, f) optionally solvents.

3. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein R, R.sup.1, R.sup.2 and R.sup.3 are at the same time or each independently methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl.

4. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein n is 0, R.sup.1 and R.sup.3 are at the same time or each independently methyl or ethyl, and R.sup.2 is at the same time or mutually independently methyl or propyl.

5. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein n is 0 and R.sup.2 is methyl or propyl, and R.sup.1 is methyl or ethyl and R.sup.3═R.sup.1.

6. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein n is 0, R.sup.1 and R.sup.3 are methyl and R.sup.2 is propyl.

7. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the diisocyanate ii) is selected from isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 2,2′-dicyclohexylmethane diisocyanate (2,2′-H12MDI), 2,4′-dicyclohexylmethane diisocyanate (2,4′-H12MDI), 4,4′-dicyclohexylmethane diisocyanate (4,4′-H12MDI), 2-methylpentane diisocyanate (MPDI), pentane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate (2,2,4-TMDI), 2,4,4-trimethylhexamethylene diisocyanate (2,4,4-TMDI), norbornane diisocyanate (NBDI), methylenediphenyl diisocyanate (MDI), toluidine diisocyanate (TDI), tetramethylxylylene diisocyanate (TMXDI), xylylene diisocyanate (MXDI), individually or in a mixture.

8. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the binder b) is a hydroxyl-containing and/or amino-containing binder.

9. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the binder b) is a hydroxyl-containing polyester, polyether, polyacrylate, polycarbonate and polyurethane having an OH number of 20 to 500 mg KOH/g and a mean molar mass of 250 to 6000 g/mol, alone or in a mixture.

10. The alkoxysilane-functionalized, allophanate-containing coating composition according to claim 1, wherein the binder b) is a hydroxyl-containing polyester or polyacrylate having an OH number of 50 to 250 mg KOH/g and a mean molecular weight of 500 to 6000 g/mol, alone or in a mixture.

11. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the binder b) is at least one adduct of an isocyanatotrialkoxysilane and a mono- or polyhydric alcohol.

12. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the binder b) is at least one derivative of hydroxyl-containing polyethers, polyesters, polycarbonatediols or polyacrylates with isocyanatopropyltrialkoxysilane, alone or in a mixture.

13. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the binder b) is aminopropyltriethoxysilane, aminomethyltrimethoxysilane or aminomethyltriethoxysilane, alone or in a mixture.

14. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the component c) is a polyisocyanate selected from isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 2,2′-dicyclohexylmethane diisocyanate (2,2′-H12MDI), 2,4′-dicyclohexylmethane diisocyanate (2,4′-H12MDI), 4,4′-dicyclohexylmethane diisocyanate (4,4′-H12MDI), 2-methylpentane diisocyanate (MPDI), pentane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate (2,2,4-TMDI), 2,4,4-trimethylhexamethylene diisocyanate (2,4,4-TMDI), norbornane diisocyanate (NBDI), methylenediphenyl diisocyanate (MDI), toluidine diisocyanate (TDI), tetramethylxylylene diisocyanate (TMXDI), xylylene diisocyanate (MXDI), individually or in a mixture.

15. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the component c) is an isocyanurate, more particularly of IPDI and/or HDI.

16. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the catalyst d) is selected from the group consisting of metal carboxylate, tertiary amine, amidine, guanidine, quaternary ammonium salts, tetraalkylammonium salts, quaternary phosphonium salts, metal acetylacetonates, quaternary ammonium acetylacetonates, quaternary phosphonium acetylacetonates, carboxylic acids, aluminium alkoxides, zirconium alkoxides, titanium alkoxides and/or boron alkoxides and/or esters thereof, phosphorus- and nitrogen-containing catalysts, sulphonic acids, alone or in a mixture.

17. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the catalyst d) is selected from the group consisting of tetraethylammonium benzoate, tetrabutylammonium hydroxide, tetraethylammonium acetylacetonate, tetrabutylammonium acetylacetonate, dibutyltin dilaurate, zinc acetylacetonate and zinc ethylhexanoate.

18. The alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the additive e) used is selected from the group consisting of solvents, stabilizers, light stabilizers, additional crosslinkers, fillers, pigments, flow control agents or rheological assistants, alone or in a mixture.

19. The process for producing the alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1 by mixing components a)-f).

20. A composition comprising the alkoxysilane-functionalized, allophanate-containing coating compositions according to claim 1, wherein the composition may be a paint compositions, adhesive compositions, sealant compositions or metal-coating compositions.

Description

EXAMPLES

Ingredients:

[0117] Vestanat® EP-UPMS: trimethoxysilylpropyl methylcarbamate (Evonik Resource Efficiency GmbH) Vestanat® IPDI: isophorone diisocyanate (Evonik Resource Efficiency GmbH)
Vestanat® TMDI: mixture of 2,2,4-trimethylhexamethylene diisocyanate (2,2,4-TMDI) and 2,4,4-trimethylhexamethylene diisocyanate (Evonik Resource Efficiency GmbH)
Vestanat® HT 2500/100: hexamethylene 1,6-diisocyanate, homopolymeric (isocyanurate type) (Evonik Resource Efficiency GmbH)
Vestanat® EP Cat 11 B: tetraethylammonium benzoate in butanol (Evonik Resource Efficiency GmbH)
Tegoglide® 410: lubricity and antiblocking additive based on a polyethersiloxane copolymer (Evonik Resource Efficiency GmbH)
Vestanat® EP-M60: linear, short-chain, silane-functionalized crosslinker (Evonik Resource Efficiency GmbH)
Vestanat® EP-M95: branched, short-chain silane-functionalized crosslinker (Evonik Resource Efficiency GmbH)
Vestanat® EP-M120: linear, long-chain silane-functionalized crosslinker (Evonik Resource Efficiency GmbH)
Setalux® 1760 VB-64: Polyacrylate polyol, Nuplex Resins B.V.
Tinuvin® 292: sterically hindered amine, light stabilizer; BASF SE
Tinuvin® 900: UV absorber; BASF SE

Preparation

Example 1

Alkoxysilane-Functionalized, Allophanate-Containing Binder, Component 1a

[0118] 340.2 g of Vestanat® EP-UPMS, 0.3 g of zinc(II) ethylhexanoate and 159.7 g of Vestanat® IPDI were charged to a three-necked flask with reflux condenser, blanketed with nitrogen and heated with stirring to 100° C. After heating for 20 hours, an NCO content of 1.4 wt % NCO was obtained. Then 10.84 g of butanol were added and the mixture was heated at 100° C. for an hour until an NCO content of <0.1 wt % NCO was reached. The product after cooling to room temperature is the alkoxysilane-functionalized, allophanate-containing binder, component 1a, as a clear liquid having a viscosity of 14.3 Pas (at 23° C.).

Example 2

Alkoxysilane-Functionalized, Allophanate-Containing Binder, Component 2a

[0119] 474.6 g of Vestanat® EP-UPMS, 0.22 g of zinc(II) ethylhexanoate and 211.8 g of Vestanat® TMDI were charged to a three-necked flask with reflux condenser, blanketed with nitrogen and heated with stirring to 100° C. After heating for 24 hours, an NCO content of 0.8 wt % NCO was obtained. Then 10.35 g of butanol were added and the mixture was heated at 65° C. for three hours until an NCO content of <0.1 wt % NCO was reached. The product after cooling to room temperature is the alkoxysilane-functionalized, allophanate-containing binder, component 2a as a clear liquid having a viscosity of 1170 mPas (at 23° C.).

Comparative Example 3A

Alkoxysilane-Functionalized, Allophanate-Containing Binder, Component 3a (Comparative Example)

[0120] 44.3 g of Vestanat® EP-UPMS, 0.01 g of zinc(II) ethylhexanoate and 35.7 g of Vestanat® HT 2500/100 were charged to a three-necked flask with reflux condenser, blanketed with nitrogen and heated with stirring to 100° C. until the NCO content of <0.1 wt % was reached. Then, with heating maintained, 20 g of butyl acetate were added in order to lower viscosity. The resulting alkoxysilane-functionalized, allophanate-containing binder, component 3a, is a clear liquid having a viscosity of 750 mPas (at 23° C.).

TABLE-US-00001 TABLE I Composition of the inventive clearcoats and comparative examples (amounts in grams) I II As per As per III IV V VI Item invention invention Comparison Comparison Comparison Comparison 1 Alkoxysilane- 26.36 functionalized, allophanate-containing binder component 1a) 2 Alkoxysilane- 27.79 functionalized, allophanate-containing binder component 2a) 3 Alkoxysilane- 29.81 functionalized, allophanate-containing binder component 3a) (comparative) 4 Comparative example: 26.79 Vestanat ® EP-M95 5 Comparative example: 26 Vestanat ® EP-M60 6 Comparative example: 53.2 Vestanat ® EP-M120 7 Setalux ® 1760 VB-64 41.18 43.41 36.79 41.85 40.6 41.6 (64% form), component b) 8 Vestanat ® EP-CAT 11 1.05 1.11 0.95 1.06 1.0 1.1 B component d) 9 TegoGlide ® 410 (10% 0.50 0.49 0.49 0.48 0.49 0.5 in butyl acetate) 10 Tinuvin ® 292 0.27 0.28 0.23 0.27 0.26 0.27 11 Tinuvin ® 900 (8% in 3.30 3.47 2.94 3.34 3.25 3.33 xylene) 12 Butyl acetate/xylene 27.34 23.45 27.20 26.21 28.4 0 (1:1)

Clearcoats

[0121] For the formulation of the inventive clearcoat materials and of the comparative examples, the components of the compositions represented in Table 1 were mixed with one another immediately prior to processing.

[0122] The viscosity of the formulations, determined as the flow time in the DIN 4 cup at 23° C., was approximately 20 seconds.

[0123] Table 2 sets out the potlives of compositions I-VI. The potlives were determined as follows: The liquid sample for determination (at least 70 ml) is introduced into a 100 ml glass vial and provided vertically with a metal pin; hanging at the end of the pin immersed in the sample is a circular metal plaque having a diameter of approximately 2 cm. The glass vial is provided with a perforated lid and the metal pin is clamped into the gelation time instrument (Techne Gelation Timer). The sample is now in a water tank set at room temperature (23° C.) (Lauda thermostat model BK2). The metal pin in the sample moves up and down in oscillation at a constant rhythm until the resistance of the sample is greater than the force of the gelation time instrument. In this case, the metal pin remains stationary; the sample is “gelled”. The time which elapses between the start of the oscillating movement of the metal pin and the end thereof is reported on the display of the gelation instrument.

TABLE-US-00002 TABLE 2 Potlives of compositions I-VI Clearcoat system Potlife (h) I 18.8 II 14.0 III (Comparison) 5.8 IV (Comparative example) 4.3 V (Comparative example) 4.0 VI (Comparative example) 2.0

[0124] From the potlives set out in Table 2 it is clearly evident that the inventive alkoxysilane-functionalized, allophanate-containing binders I-II have a much longer potlife than the Comparative Examples III-VI. From the prior art (Comparative Examples IV-VI) there was no expectation that the potlife would be prolonged by a multiple when using the inventive alkoxysilane-functionalized, allophanate-containing binders I-II.

[0125] The mechanical characteristics were determined by applying all of the coating materials to phosphatized steel panels (Chemetall Gardobond 26S/60/OC) with a 120 μm bar coater and curing them at 160° C. for 22 minutes.

TABLE-US-00003 TABLE 3 Film properties of compositions I-III after curing at 160° C. (22 min) III Composition I II (Comparison) Cross-cut 0 0 2 Pendulum hardness (König) 188 165 184 [s] after 1 d MEK test [ASTM D 4752] >150 >150 >150 (Double rubs, 1 kg applied weight)

[0126] The film properties of coatings I and II, which comprise the inventive alkoxysilane-functionalized, allophanate-containing binder components 1 and 2, exhibit improved adhesion (cross-cut) for approximately the same pendulum hardness and MEK resistance as Comparative Example III. In the case of formula III in particular, which contains the triply functionalized Comparative Example 3, the expectation, on the basis of the higher degree of crosslinking, would have been a greater hardness than the coatings I and II, which comprise the inventive alkoxysilane-functionalized, allophanate-containing binder components 1 and 2.