ALKOXYSILANE-FUNCTIONALIZED ALLOPHANATES

Abstract

The present invention relates to alkoxysilane-functionalized allophanates, to methods for production thereof, and to the use thereof. In particular, the alkoxysilane-functionalized allophanate includes the reaction product of A) at least one alkoxysilane group-containing monourethane A) 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 B) at least one diisocyanate B), in a molar ratio of A) to B) of 3:1 to 1.5:1.

Claims

1. An alkoxysilane-functionalized allophanate comprising the reaction product of A) at least one alkoxysilane group-containing monourethane A) 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 B) at least one diisocyanate B), in a molar ratio of A) to B) of 3:1 to 1.5:1.

2. An alkoxysilane-functionalized allophanate, obtained by reacting A) at least one alkoxysilane group-containing monourethane A) 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 B) at least one diisocyanate B), in a molar ratio of A) to B) of from 3:1 to 1.5:1, C) optionally in the presence of at least one catalyst C), and D) optional reaction of the residual amount of NCO groups of B) with an alcohol D).

3. The alkoxysilane-functionalized allophanate according to claim 1, wherein the molar ratio of A) to B) is from 2.5:1 to 1.8:1.

4. The alkoxysilane-functionalized allophanate 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.

5. The alkoxysilane-functionalized allophanate 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.

6. The alkoxysilane-functionalized allophanate 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.

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

8. The alkoxysilane-functionalized allophanate according to claim 1, wherein the diisocyanate B) is selected from isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 2,2-di cyclohexylmethane 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.

9. The alkoxysilane-functionalized allophanate according to claim 1, wherein the diisocyanate B) is selected from IPDI, 4,4′-H12MDI, HDI and mixtures of 2,2,4-TMDI and 2,4,4-TMDI, individually or in a mixture.

10. The alkoxysilane-functionalized allophanate according to claim 1, wherein the component c) is selected from the group consisting of metal carboxylates, tert-amines, amidine, guanidine, quaternary ammonium salts, tetraalkylammonium salts, quaternary phosphonium salts, metal acetylacetonates, quaternary ammonium acetylacetonates, quaternary phosphonium acetylacetonates, alone or in a mixture.

11. The alkoxysilane-functionalized allophanate according to claim 1, wherein the component c) is zinc acetylacetonate and/or zinc ethylhexanoate.

12. The alkoxysilane-functionalized allophanate according to claim 1, wherein the alcohol D) is selected from methanol, ethanol, propanol, isopropanol, 1-butanol, 2-butanol, pentanol, ethyl-2-hexanol, 1-hexanol.

13. A method for preparing alkoxysilane-functionalized allophanates according to claim 1, by reacting A) at least one alkoxysilane group-containing monourethane A) 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 B) at least one diisocyanate B), in a molar ratio of A) to B) of from 3:1 to 1.5:1, C) optionally in the presence of at least one catalyst C), and D) optional reaction of the residual amount of NCO groups of B) with an alcohol D).

14. The method according to claim 13, wherein the reaction is carried out at temperatures in the range from 15 to 40° C.

15. The method according to claim 13, wherein the reaction is carried out at temperatures in the range from 80 to 220° C.

16. The method according to claim 13, wherein the reaction of the residual amount of NCO groups of B) with an alcohol D) is carried out at temperatures in the range of 30 - 150° C.

17. The method according to claim 13, wherein the reaction is carried out in the presence of zinc acetylacetonate and/or zinc ethylhexanoate as catalyst C).

18. The method according to claim 13, wherein the residual amount of NCO groups of B) is reacted with an alcohol D) at the ratio of the NCO groups to OH groups of the alcohol D) of from 0.8:1 to 1.2:1.

19. A composition, which may be coating compositions and paint compositions for metal, plastic, glass, wood, MDF (Middle Density Fibreboards) or leather substrates or other heat-resistant substrates, the composition comprising the alkoxysilane-functionalized allophanates according to claim 1.

20. An adhesive composition for bonding of metal, plastic, glass, wood, MDF or leather substrates or other heat-resistant substrates, the adhesive composition comprising the alkoxysilane-functionalized allophanates according to claim 1.

21. A coating composition, adhesives or sealant, comprising at least one alkoxysilane-functionalized allophanate according to claim 1.

Description

EXAMPLES

[0074] Feedstocks:

[0075] Vestanat® EP-UPMS: Trimethoxysilylpropyl methyl carbamate (Evonik Resource Efficiency GmbH)

[0076] Vestanat® IPDI: Isophorone diisocyanate (Evonik Resource Efficiency GmbH)

[0077] Vestanat® TMDI: Mixture of 2,2,4-trimethylhexamethylene diisocyanate (2,2,4-TMDI) and 2,4,4-trimethylhexamethylene diisocyanate (Evonik Resource Efficiency GmbH)

[0078] Vestanat® HT 2500/100: Hexamethylene-1,6-diisocyanate, homopolymer (isocyanurate type) (Evonik Resource Efficiency GmbH)

[0079] Vestanat® EP Cat 11 B: Tetraethylammonium benzoate in butanol (Evonik Resource Efficiency GmbH)

[0080] Tegoglide® 410: Glide and antiblocking additive based on a polyether siloxane copolymer (Evonik Resource Efficiency GmbH)

[0081] 1. Preparation

Example 1

Alkoxysilane-Functionalized Allophanate 1

[0082] A three-necked flask with reflux condenser was initially charged with 340.2 g of Vestanat® EP-UPMS, 0.3 g of zinc(II) ethylhexanoate and 159.7 g of Vestanat® IPDI, flushed with nitrogen and heated to 100° C. with stirring. After heating for 20 hours, an NCO content of 1.4% by weight

[0083] NCO was obtained. 10.84 g of butanol were then added and the mixture was heated at 100° C. for 1 h, until an NCO content of <0.1% by weight NCO was reached. After cooling to room temperature, the alkoxysilane-functionalized allophanate 1 according to the invention is obtained as a clear liquid with a viscosity of 14.3 Pas (at 23° C.).

Example 2

Alkoxysilane-Functionalized Allophanate 2

[0084] A three-necked flask with reflux condenser was initially charged with 474.6 g of Vestanat® EP-UPMS, 0.22 g of zinc(II) ethylhexanoate and 211.8 g of Vestanat® TMDI, flushed with nitrogen and heated to 100° C. with stirring. After heating for 24 hours, an NCO content of 0.8% by weight NCO was obtained. 10.35 g of butanol were then added and the mixture was heated at 65° C. for 3 h until an NCO content of <0.1% by weight NCO was reached. After cooling to room temperature, the alkoxysilane-functionalized allophanate 2 according to the invention is obtained as a clear liquid with a viscosity of 1170 mPas (at 23° C.).

Comparative Example 3A

Alkoxysilane-Functionalized Allophanate 3A (Comparative Example)

[0085] A three-necked flask with reflux condenser was initially charged with 44.3 g of Vestanat® EP-UPMS, 0.01 g of zinc(II) ethylhexanoate and 35.7 g of Vestanat® HT 2500/100, flushed with nitrogen and heated to 100° C. with stirring until the NCO content of <0.1% by weight was achieved. With continued heating for the purpose of lowering viscosity, 20 g of butyl acetate were then added. The alkoxysilane-functionalized allophanate 3 thus obtained is a clear liquid with a viscosity of 750 mPas (at 23° C.).

Comparative Example 3B

Alkoxysilane-Functionalized Allophonate 3B (Comparative Example)

[0086] A three-necked flask with reflux condenser was initially charged with 335.7 g of Vestanat® EP-UPMS, 0.076 g of zinc(II) ethylhexanoate, 237.8 g of Vestanat® HT 2500/100 and 152 g of xylene, blanketed with nitrogen and heated to 100° C. with stirring until the NCO content of 1% by weight was reached. 13.58 g of butanol were then added and the mixture heated at 100° C. for 0.5 h until an NCO content of <0.1% by weight NCO was reached. The alkoxysilane-functionalized allophanate 3b thus obtained is a clear liquid with a viscosity of 542 mPas (at 23° C.).

[0087] 2. Preparation of Clearcoats from the Alkoxysilane-Functionalized Allophanates as Coating Compositions

[0088] For the formulation of the clearcoats according to the invention and the comparative examples, the components of the compositions shown in Table 1 and 2 were mixed directly before processing.

[0089] The viscosity of the formulations, determined as the flow time in the DIN 4 cup at 23° C., was approximately 60 seconds.

TABLE-US-00001 TABLE 1 Composition of the inventive clearcoats and comparative example of systems curing at room temperature (RT) Data in % by weight IIIa IIIb (com- (com- para- para- Item I II tive) tive) 1 Allophanate 1 91.24 2 Allophanate 2 99.00 3 Comparative example: 98.5 Allophanate 3a (comparative) 4 Comparative example: 98.5 Allophanate 3b (comparative) 5 1,8-Diazabicyclo[5.4.0]undec- 0.92 1.0 1.0 1.0 7-ene (DBU) 6 Xylene 7.79 0.45 0.45 7 Tegoglide 410 0.05 0.45 0.05

[0090] Based on the resin, the content of catalyst DBU is 1.0% in examples I and II and 1.25% DBU in example IIIa and b.

TABLE-US-00002 TABLE 2 Composition of the inventive clearcoats and comparative example of hot-curing systems Data in % by weight Va Vb Item IV (comparative) (comparative) 1 Allophanate 1 84.00 2 Allophanate 2 3 Comparative example: 88.53 Allophanate 3a (comparative) 4 Comparative example: 88.53 Allophanate 3b (comparative) 5 Vestanat Cat 11 B 1.71 1.45 1.45 6 Xylene 14.29 10.02 10.02

[0091] Based on the resin, the content of catalyst Vestanat Cat 11 B is 1.0% in all examples.

[0092] The mechanical characteristics were determined by applying all of the coating materials to phosphatized steel plates (Chemetall Gardobond 26S/60/OC) using a 100 p.m doctor blade and curing them at room temperature (23° C.), Table 3, or at 140° C., Table 4.

TABLE-US-00003 TABLE 3 Coating properties of the compositions I-III after curing at 23° C. (7 days) IIIa IIIb Composition I II (comparative) (comparative) Pendulum hardness 189 168 158 140 (König) [s] n 7 d MEK test >150 >150 >150 >150 [ASTM D 4752] (Double rubs, 1 kg applied weight) Appearance of the glossy glossy glossy glossy coating

[0093] The coating properties of coatings I and II, comprising the inventive alkoxysilane-functionalized allophanate 1 or 2, show significantly higher pendulum hardness than comparative examples IIIa and b. In particular, in the three-fold functionalized product in coating material IIIa and b, a greater hardness would have been expected due to the higher degree of crosslinking.

TABLE-US-00004 TABLE 4 Coating properties of the compositions IV-V after curing at 140° C. (22 min) Va Vb Composition IV (comparative) (comparative) Pendulum hardness 178 118 59 (König) [s] n 1 d MEK test >150 >150 >150 [ASTM D 4752] (Double rubs, 1 kg applied weight) Appearance of the glossy matt glossy coating

[0094] The coating properties of coating IV comprising the inventive alkoxysilane-functionalized allophanate 1 shows a significantly higher pendulum hardness than comparative examples V a and b. In particular, in the three-fold functionalized product in coating material V a and b, a greater hardness would have been expected due to the higher degree of crosslinking. In addition, coating IV, with its glossy surface, exhibits a better appearance than the matt coating Va.

[0095] The results from Table 3 and 4 show that the inventive alkoxysilane-functionalized allophanates may be used for the development of highly crosslinked, particularly rigid coatings and only these can be used in this case as sole binder both in cold and hot curing, even solvent-free if required.