TIN-FREE CATALYSIS OF SILANE-FUNCTIONAL POLYURETHANE CROSSLINKERS

Abstract

The present invention relates to a composition at least comprising A) an adduct of isocyanatosilanes with hydroxy-functional compounds and B) a tin-free catalyst, and also to a coating composition comprising at least the composition and to the use of the coating composition.

Claims

1. An aminosilane-free composition comprising A) an adduct of isocyanatosilanes with hydroxy-functional compounds and B) a tin-free catalyst selected from the group consisting of nitrogen-containing catalysts, salts and esters of oxoacids of phosphorus and alkylammonium halides, wherein the hydroxy-functional compounds are selected from the group consisting of monoalcohols or polyols, i.e. diols, triols, tetrols and hydroxyl group-containing polymers having an OH number of 10 to 500 mg KOH/gram and a number-average molar mass of 250 to 6000 g/mol, wherein the hydroxyl group-containing polymers are selected from the group consisting of polyesters, polyethers, polyacrylates, polycarbonates, epoxy resins, cellulose derivatives, FEVE (fluoroethylene vinyl ether), alkyds and polyurethanes, wherein the polyurethanes consist of polyols and diisocyanate monomers; and wherein the amount of component A) is 40 to 99% by weight and the amount of component B) is 0.01 to 3% by weight, based in each case on the total composition.

2. The aminosilane-free composition according to claim 1, wherein the adduct of isocyanatosilanes includes an isocyanatosilane is a compound of the formula (I)
OCN-(alkyl)-Si(alkoxy).sub.3 (I) wherein the alkyl in formula (I) above corresponds to a linear or branched alkyl group having 1 to 4 carbon atoms and the alkoxy in formula (I) above each corresponds mutually independently to a methoxy, ethoxy, propoxy or butoxy group, wherein the three alkoxy groups in the compound of the formula (I) may in each case be identical or different from one another.

3. The aminosilane-free composition according to claim 2, wherein the alkoxy in the formula (I) is in each case mutually independently selected from methoxy and ethoxy groups.

4. The aminosilane-free composition according to claim 3, wherein the alkoxy groups, in the case that all three alkoxy groups are identical, are not methoxy groups.

5. The aminosilane-free composition according to claim 1, wherein the ratio of OH groups of the hydroxy-functional compounds to NCO groups of the isocyanatosilanes is from 0.8:1 to 1.2:1.

6. The aminosilane-free composition according to claim 1, wherein the tin-free catalyst B) is an alkylammonium halide.

7. The aminosilane-free composition according to claim 7, wherein the tin-free catalyst B) is tetramethylammonium fluoride, tetrapropylammonium fluoride, tetraethylammonium fluoride, tetrabutylammonium fluoride or a mixture thereof.

8. A one-component (1K) coating composition comprising at least the aminosilane-free composition according to claim 1.

9. A one-component coating composition according to claim 8 which comprises at least one auxiliary and/or additive and/or at least one solvent.

10. The one-component coating composition according to claim 9, wherein the at least one auxiliary and/or additive is selected from the group consisting of stabilizers, light stabilizers, catalysts, pigments, levelling agents or rheological assistants, such as so-called sag control agents, microgels, fumed silicon dioxide, inorganic or organic colourcolor pigments and/or effect pigments or mixtures of two or more thereof.

11. A composite comprising the one-component coating composition according to claim 8 wherein the composite comprises wood, plastic, glass or metal.

12. A coating comprising the one-component coating composition according to claim 8.

13. The aminosilane-free composition according to claim 1, wherein the tin-free catalyst B) is an alkylammonium fluoride.

14. A two-component (2K) coating composition comprising at least the aminosilane-free composition according to claim 1.

15. A two-component coating composition according to claim 14 which comprises at least one auxiliary and/or additive and/or at least one solvent.

16. The two-component coating composition according to claim 15, wherein the at least one auxiliary and/or additive is selected from the group consisting of stabilizers, light stabilizers, catalysts, pigments, levelling agents or rheological assistants, such as so-called sag control agents, microgels, fumed silicon dioxide, inorganic or organic color pigments and/or effect pigments or mixtures of two or more thereof.

17. A composite comprising the two-component coating composition according to claim 14 wherein the composite comprises wood, plastic, glass or metal.

18. A coating comprising the two-component coating composition according to claim 14.

Description

EXAMPLES

Example 1

Production of Coating Compositions (1K)

[0068] The individual substances, depending on the formula, are placed in succession in a glass bottle and stirred until a homogenous and thoroughly mixed solution is formed. Prior to addition to the composition, the alkylammonium halides TMAF and TBAF used were dissolved to give a 10% solution in ethanol (except in Example 2/composition N). A levelling agent (Tego Glide 410/10% in n-butyl acetate) was added to all coating compositions.

[0069] Production of the Coatings:

[0070] The compositions produced as described above are applied to test panels (Chemetall Group/Gardobond 26S 60 OC) using a coating bar having a wet film thickness of about 120 m. An overview of the compositions produced are found in Table 1. All amounts are stated in percent by weight.

[0071] After application, the test panels with the coating are stored in a controlled-climate chamber at 23 C. and a relative humidity of 50%. After one day, the pendulum hardness (in accordance with Konig) of the coatings produced is determined. In addition, the dust-dry time is recorded directly after application of the coating.

[0072] The basis for the pendulum hardness is that the greater the damping effect of the substrate and the absorption of swing energy, the more quickly the amplitude of swaying of the self-supporting pendulum is reduced. The sample plate (with coating) is placed on the reciprocating platen. With the lever arm, which can be operated from the outside, the reciprocating platen is subsequently moved up to the pendulum. The pendulum is deflected to the 6 scale position, fixed to the wire trigger, and then let go. A determination is made of the number of swings needed to cause the pendulum swing to subside from 6 to 3 relative to the vertical. Multiplying the swings by a factor of 1.4 gives the calculated Konig pendulum damping in seconds. The measurement is conducted at 2 different positions within the sample and the mean is calculated.

[0073] The drying time of the coating material is determined by determination of the dust-dry time in accordance with EN ISO 9177 (3:2010).

[0074] For this purpose, the coating substrate is coated with the coating to be tested at the target film thickness. The time point is noted. At intervals of 10 minutes, ca. 0.3 to 0.5 g of heavy glass beads (glass beads 0: 250-500 m/manufacturer: Carl-Roth GmbH+Co. KG) are scattered carefully onto the coating with a small spoon/spatula from a point at a height of 0.5 cm (diameter of the glass bead pile ca. 1.5 to 2.0 cm). Every 10 minutes, a new glass bead-free point is impacted with glass beads. In the case of rapid systems, the time interval is reduced to 5 minutes, while in the case of slow systems they are initially increased to 15 to 30 minutes. Towards the end of the curing time, the time intervals are then shortened again to 10 minutes. At each point, the time interval since application of the coating is noted. If the coating is optically dried, the glass beads are wiped from the panel using a soft hair brush and the time recorded at the time point at which no glass beads adhere to the film surface. If glass beads adhere to the film surface, the test is continued.

[0075] The results obtained for the coatings produced are presented in Table 2.

TABLE-US-00001 TABLE 1 Overview of the compositions produced of Example 1) A* B* C* D E F G H I J VESTANAT EP-M 60 (1) 89.41 98.50 98.50 98.50 98.50 98.50 99.00 VESTANAT EP-E 95 (2) 89.41 78.50 94.50 Dynasylan AMMO (3) 10.00 10.00 20.00 TIB Kat 218 (4) 0.09 0.09 1.0 Tego Glide 410 (5) 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Hordaphos MOB (6) 1.00 Hordaphos MDB (7) 1.00 Poly cat 102 (8) 1.00 TMG (9) 1.00 K-KAT XK-678 (10) 1.00 TMAF (11) 0.05 TBAF*3H.sub.2O (12) 0.50 Ethanol 0.45 4.50 n-Butyl acetate 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 The compositions marked with * are comparative examples (1) VESTANAT EP-M 60, adduct of 3-isocyanatopropyltrimethoxysilane and 1,6-hexanediol (ratio of 3-isocyanatopropyltrimethoxysilane to 1,6-hexanediol corresponds to 2:1) (2) VESTANAT EP-E 95, adduct of 3-isocyanatopropyltriethoxysilane and 1,9-nonanediol (ratio of 3-isocyanatopropyltriethoxysilane to 1,9-nonanediol corresponds to 2:1) (3) Dynasylan AMMO, 3-aminopropyltrimethoxysilane from Evonik Resource Efficiency GmbH (4) TIB Kat 218, dibutyltin dilaurate, TIB Chemicals AG (5) Tego Glide 410, polyether siloxane copolymer, Evonik Resource Efficiency GmbH (6) Hordaphos MOB, phosphoric acid butyl esters, Clariant (7) Hordaphos MDB, phosphoric acid butyl esters, Clariant (8) Polycat DBU, diazabicycloundecene, Evonik Resource Efficiency GmbH (9) Tetramethylguanidine, Merck Millipore (10) K-KAT XK-678, alkyl acid phosphate, King Industries (11) Tetramethylammonium fluoride, Sigma Aldrich (12) Tetrabutylammonium fluoride trihydrate, Sigma Aldrich

TABLE-US-00002 TABLE 2 Results of the determination of pendulum hardness and dust-dry time Period prior to measurement A* B* C* D E F G H I J Mean pendulum hardness 1 day 97 Liquid 48 109 102 120 116 109 101 113 Mean dust-dry time (min.) 35 >210 >210 25 40 15 30 25 5 22

[0076] It is evident from Table 2 that the coating compositions according to the invention comprising the tin-free catalysts (samples D to J) cure comparably rapidly or even more rapidly at room temperature than the comparative examples with tin-containing catalyst and aminosilane (samples A*, B* and C*). The same applies also to the pendulum hardnesses which are almost exclusively higher in the examples according to the invention. All catalysts according to the invention listed are therefore an alternative to the known tin-containing catalysts and also the aminosilane.

[0077] Surprisingly, even rapid curing of ethoxy-based adducts (2) could also be achieved at room temperature by using alkylammonium halides (sample J), which was not possible with the known compositions (sample B* and C*).

Example 2

Production of Coating Compositions (2K):

[0078] The individual substances, depending on the formula, are placed in succession in a glass bottle and stirred until a homogenous and thoroughly mixed solution is formed. The NCO:OH ratio was adjusted in each case to a ratio of 1:1. The viscosity of the formulations, determined as the flow time in the DIN 4 cup at 23 C., is approximately 20 seconds. Prior to addition to the composition, the alkylammonium halides TMAF and TBAF used were dissolved in ethanol (10% solution of TMAF and TBAF). A levelling agent (Tego Glide 410/10% in n-butyl acetate) was added to all coating compositions.

[0079] Production of the Coatings:

[0080] The compositions produced as described above are applied to test panels (Chemetall Group/Gardobond 26S 60 OC) using a coating bar having a wet film thickness of about 120 m. An overview of the compositions produced are found in Table 3. All figures are stated in percent by weight.

[0081] After application, the test panels are cured with the coating for 30 minutes at 130 C. in an air circulation oven. After one day, the pendulum hardness (in accordance with Konig) of the coatings produced is determined.

[0082] The results obtained for the coatings produced are presented in Table 4.

TABLE-US-00003 TABLE 3 Overview of the compositions produced of Example 2) K* L M N Setalux 1767 VV-65 (1) 46.64 46.39 46.39 46.39 VESTANAT HT 2500 L (2) 17.20 17.11 17.11 17.11 VESTANAT EP-M 60 (3) 8.24 9.11 9.11 9.11 Tego Glide 410 (4) 0.05 0.05 0.05 0.05 Butyl acetate/xylene (5) 26.49 26.35 26.35 26.35 Dynasylan AMMO (6) 0.92 TIP Kat 218 (7) 0.01 Hordaphos MOB (8) 0.54 Polycat 102 (9) 0.54 TBAF*3H.sub.2O (10) 0.54 n-Butyl acetate 0.45 0.45 0.45 0.45 The composition marked with * is a comparative example. (1) Setalux 1767 VV-65, polyacrylate polyol, Nuplex Resins B.V. (2) VESTANAT HT 2500 L, hexamethylene-1,6-diisocyanate, homopolymer (isocyanurate type), 90% in n-butyl acetate/solvent naphtha (1:1), Evonik Resource Efficiency GmbH (3) VESTANAT EP-M 60, adduct of 3-isocyanatopropyltrimethoxysilane and 1,6-hexanediol (ratio of 3-isocyanatopropyltrimethoxysilane to 1,6-hexanediol corresponds to 2:1) (4) Tego Glide 410, polyether siloxane copolymer, Evonik Resource Efficiency GmbH (5) o-Xylene/n-butyl acetate (1:1 mixture), Merck Millipore (6) Dynasylan AMMO, 3-aminopropyltrimethoxysilane, Evonik Resource Efficiency GmbH (7) TIP Kat 218, dibutyltin dilaurate, TIB Chemicals AG (8) Hordaphos MOB, phosphoric acid butyl ester, Clariant (9) Polycat DBU, diazabicycloundecene, Evonik Resource Efficiency GmbH (10) Tetrabutylammonium fluoride trihydrate, Sigma Aldrich

TABLE-US-00004 TABLE 4 Results of the determination of the pendulum hardness and dust-dry time Period of the Mean pendulum hardness measurement K* L M N 1 day 52 128 161 146 Mean dust-dry time (min.) K* L M N >210 60 90 30

[0083] It is apparent from Example 2 that the comparative example (sample K*) shows a poor compatibility with 2K PUR compositions which manifests as an inadequate pendulum hardness.

[0084] If, however, the catalyst systems according to the invention (samples L to N) are used, sufficient hardnesses can be generated despite increased curing temperatures.

[0085] The compositions according to the invention can be cured while retaining the advantageous properties both at room temperature (Example 1) and even at elevated temperatures (Example 2).