TWO-COMPONENT POLYURETHANE COATINGS HAVING IMPROVED POT LIFE WITHOUT A LOSS OF WEATHERING RESISTANCE

Abstract

The present invention relates to a 2-component system containing at least one specific N-, S-, O- and Si-containing compound. The invention further relates to a process for preparing silicon-containing polyurethanes, comprising reacting the first component with the second component of the 2-component system according to the present invention, and to the silicon-containing polyurethanes obtained therefrom. In addition, the invention relates to the use of the 2-component system according to the present invention for the production of coating, sealants or adhesives.

Claims

1. A 2-component system comprising a first component, which comprises: A1) at least one compound having at least one Zerewitinoff-active group; B1) optionally at least one catalyst; C1) optionally at least one solvent; and D1) optionally at least one additive, and a second component, which comprises: A2) at least one polyisocyanate; and B2) at least one of the following compounds of the formula (I): ##STR00008## where R.sup.1 to R.sup.3 each independently of one another are identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen, wherein at least one of the radicals R.sup.1, R.sup.2 and R.sup.3 is joined to the silicon atom via an oxygen atom, X independently at each instance is identical or different, saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 6 carbon atoms; Y independently at each instance are identical or different, saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen; and Z is a structural unit which is derived from an at least difunctional polyol having a number-average molecular weight M.sub.n of 270 to 22 000 g/mol; or is a polyhydric alcohol and/or ether alcohol or ester alcohol containing 2 to 14 carbon atoms; C2) optionally at least one solvent; D2) optionally at least one compound which differs from the compound of formula (I) and is obtained by reacting at least one isocyanate group with a secondary amine containing a silane group.

2. The 2-component system of claim 1, wherein the at least one compound A1 is selected from the group consisting of polyols, polyamines, polyether polyols, polyester polyols, polyurethane polyols, polysiloxane polyols, polycarbonate polyols, polyether polyamines, polybutadiene polyols, polyacrylate polyols and polymethacrylate polyols and copolymers thereof.

3. The 2-component system of claim 1, wherein the at least one catalyst B1 is selected from the class of tin catalysts, bismuth catalysts, zinc catalysts, zirconium catalysts and amine bases.

4. The 2-component system of claim 1, wherein the at least one solvent C1 is selected from aromatic solvents and aliphatic solvents, and mixtures thereof.

5. The 2-component system of claim 1, wherein the at least one additive D1 is selected from UV stabilizers, antioxidants and leveling agents, or mixtures thereof.

6. The 2-component system of claim 1, wherein the at least one polyisocyanate A2 is selected from the group consisting of di- or triisocyanates, such as butane 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 4-isocyanatomethyloctane 1,8-diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate), decamethylene 1,10-diisocyanate, 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane, 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, naphthalene 1,5-diisocyanate, diisocyanatodiphenylmethane, such as 2,2′-, 2,4′- and 4,4′-MDI or mixtures thereof, diisocyanatomethylbenzene, such as tolylene 2,4- and 2,6-diisocyanate, and technical grade mixtures of the two isomers, and 1,3- and/or 1,4-bis(isocyanatomethyl)benzene, 3,3′-dimethyl-4,4′-biphenyl diisocyanate, paraphenylene 1,4-diisocyanate and cyclohexyl diisocyanate and the oligomers of higher molecular weight which are obtainable individually or in a mixture from the above and have biuret, uretdione, isocyanurate, iminooxadiazinedione, allophanate, urethane and carbodiimide/uretonimine structural units.

7. The 2-component system of claim 1, wherein D2 is selected from i) at least one compound of the formula (II) ##STR00009## where R.sup.1, R.sup.2 and R.sup.3 each independently of one another are identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen, with the proviso that at least one of the radicals R.sup.1, R.sup.2 and R.sup.3 is joined to the silicon atom via an oxygen atom, X is a linear or branched organic radical having up to 6 carbon atoms and Y is a linear or branched, aliphatic or cycloaliphatic radical having 4 to 18 carbon atoms, W independently at each instance are a formyl or acetyl group or else a COO group having a radical G, G in this case may be mono-, di-, tri- or tetrafunctional and is a linear or branched, aliphatic or cycloaliphatic radical or a connecting unit derived therefrom having 4 to 18 carbon atoms or an optionally substituted aromatic or araliphatic radical, or ii) at least one compound of the formula (III) ##STR00010## where X independently at each instance is selected from alkoxy or alkyl radicals, or two radicals X together with the silicon atom to which they are bonded form an Si-substituted hydrocarbon ring, each having up to 10 carbon atoms, wherein the Si atom has at least one alkoxy radical, Q is a difunctional linear or branched aliphatic radical having up to 10 carbon atoms; and Z at each instance is an alkoxy radical having 1 to 10 carbon atoms.

8. The 2-component system of claim 1, wherein B2 has an isocyanate content of less than 2%.

9. The 2-component system of claim 1, wherein the constituents of the first component parts by weight of A1 and parts by weight of B1 are present in a weight ratio of 0.5 to 8 in relation to the constituents parts by weight of C1 and parts by weight of D1.

10. The 2-component system of claim 1, wherein the constituents of the second component parts by weight of A2 and parts by weight of B2 are present in a weight ratio of 0.5 to 10 to the constituents parts by weight of C2 and parts by weight of D2.

11. The 2-component system of claim 1, wherein the constituents of the first component parts by weight of A1, and optionally parts by weight of B1, parts by weight of C1 and parts by weight of D1, are present in a weight ratio of 0.6 to 11 to the constituents of the second component, parts by weight of A2, parts by weight of B2 and optionally parts by weight of C2 and parts by weight of D2.

12. A process for preparing silicon-containing polyurethanes, comprising reacting the first component with the second component of the 2-component system of claim 1.

13. A silicon-containing polyurethanes product produced by the process of claim 12.

14. (canceled)

15. A coating, sealant or adhesive produced from the 2-component system of claim 1.

Description

EXAMPLES

[0130] The examples which follow serve to illustrate the present invention, but should in no way be understood as imposing any restriction on the scope of protection.

[0131] All reported percentages are based on weight unless otherwise stated.

[0132] All experiments were conducted at 23° C. and 50% relative humidity.

[0133] NCO contents were determined titrimetrically in accordance with DIN EN ISO 11909:2007-05.

[0134] The solids content was determined in accordance with DIN EN ISO 3251:2008-06.

[0135] All viscosity measurements were made with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (Germany) to DIN EN ISO 3219/A:1994-10.

[0136] The residual monomer contents were measured in accordance with DIN EN ISO 10283:2007-11 by gas chromatography using an internal standard.

[0137] OH numbers were determined by titrimetry in accordance with DIN 53240-2: 2007-11, acid numbers in accordance with DIN EN ISO 2114:2002-06. The OH contents reported were calculated from the OH numbers determined by analysis. The reported values in each case relate to the total weight of the respective composition including any solvent also used.

[0138] The doubling of the flow times, customarily to be determined in accordance with DIN EN ISO 2431:2011-11 (“Determination of flow time with flow cups”) was not used to determine the pot life, and instead the skin formation time of the moisture-curing STP was used. By periodically touching the film surface with the end of a wooden spatula, the time at which skin adhering to the spatula tip could be pulled up from the surface was determined.

[0139] The drying times (T1, T3 and T4) were determined in accordance with DIN EN ISO 9117-5:2010-07 (drying test part 5: modified Bandow-Wolff method).

[0140] Solvent and water resistances were ascertained to DIN EN ISO 4628-1:2016-07. The solvent resistance test was carried out using the solvents xylene (also abbreviated hereinafter to “Xy”), methoxypropyl acetate (also abbreviated hereinafter to “MPA”), ethyl acetate (also abbreviated hereinafter to “EA”), and acetone (also abbreviated hereinafter to “Ac”). The contact time was 5 min in each case. For measurement of the water resistances, the contact time was 24 h in each case. The inspection was conducted according to the specified standard. The test surface is assessed visually and by scratching, using the following classification: 0=no change apparent; 1=swelling ring, hard surface, only visible change; 2=swelling ring, slight softening; 3=distinct softening (possibly slight blistering); 4=significant softening (possibly severe blistering), can be scratched through to the substrate; 5=coating completely destroyed without outside influence.

[0141] König pendulum damping was determined in accordance with DIN EN ISO 1522:2007-04 on glass plates. The STP films described were applied onto glass plates using a coating blade. The dry film thickness was 35-40 μm for all films.

[0142] All STP films described were applied onto glass plates using a coating blade. The film thickness was 35-40 μm for all films.

LIST OF TRADE NAME AND ABBREVIATIONS

[0143] Borchi Kat 22 (zinc carboxylate-based catalyst, 100%) was obtained from Borchers.

[0144] Setalux DA HS 1170 BA (OH content 3.6%, solids content 70%, viscosity 1200 mPa.Math.s) and Setalux DA 870 BA (OH content 3.6%, solids content 70%, viscosity 1200 mPa.Math.s) polyacrylate from Allnex.

[0145] Stabaxol 1 tetraisopropyldiphenylcarbodiimide from RheinChemie. Methoxypropyl acetate (MPA), butyl acetate (BA), ethyl acetate (EA), acetone (Ac) and xylene (Xy) were obtained from Azelis.

[0146] Hexamethylene diisocyanate (HDI), Desmodur XP 2565 (IPDI allophanate, 80% solids content, NCO content 12%, viscosity 2.800 mPa.Math.s) was obtained from Covestro.

[0147] Dibutyltin dilaurate (DBTL) was obtained from RheinChemie, available under the trade name Addocat 201 40P. Mercaptopropyltrimethoxysilane, orthophosphoric acid, tetraethyl orthoformate (TEOF), aminopropyltriethoxysilane and diethyl maleate were obtained from Sigma-Aldrich.

[0148] Leveling agents such as BYK-141 and BYK-311 were obtained from BYK Additives & Instruments.

[0149] Light stabilizers such as Tinuvin 292 and Tinuvin 1130 were obtained from BASF.

[0150] Black basecoat (Permahyd®, Base Coat 280) was used from Spiess Hecker.

[0151] All reagents and chemicals were used without further purification.

[0152] Synthesis of the Crosslinking Raw Materials

Preparation Example 1

[0153] A glass reactor was charged with 934 g of HDI to which 1.3 g of Borchi Kat 22 were added. 364 g of 3-mercaptopropyltrimethoxysilane were then added dropwise. The reaction solution was stirred until an NCO content of 24% by weight was reached. After addition of orthophosphoric acid (20% in i-PrOH), the unconverted monomeric HDI was removed by means of two-stage thin-film distillation at a temperature of 130° C. and a pressure of 0.1 mbar.

[0154] NCO=11.2%

[0155] Solids content=100% by weight

[0156] Viscosity=515 mPa.Math.s

Preparation Example 2

[0157] 764.91 g of 2-Setalux DA HS 1170 BA and 38.83 g of Stabaxol 1 are added to 478.03 g of the obtained compounds from preparation example 1, 15.02 g of TEOF and 10 drops of DBTL at 80° C. under dry nitrogen and the reaction is conducted until a residual NCO content of <0.3% is reached. 203.21 g of BuAc are added to the crude product. A virtually colorless, clear silane is obtained.

[0158] NCO residual content: 0.26%

[0159] Viscosity (23° C.): 723 mPa.Math.s

[0160] Solids content: 70%

Preparation Example 3

[0161] The HDI polyisocyanate used here was prepared in accordance with example 11 of EP-A 330 966. The reaction was stopped by adding dibutyl phosphate at an NCO content of the crude product of 40%. Subsequently, unconverted HDI was removed by means of thin-film evaporation at a temperature of 130° C. and a pressure of 0.2 mbar. A product was obtained with the following properties:

[0162] NCO content: 21.8%

[0163] Viscosity (23° C.): 3000 mPa.Math.s

[0164] Solids content=100% by weight

[0165] Monomeric HDI: 0.1%

[0166] Resin Formulations

Example 4 (Comparative Example)

[0167] 47.4 g of Setalux DA 870 BA were mixed with 0.25 g of BYK-141, 1.48 g of BYK-311, 0.99 g of Tinuvin 292, 1.97 g of Tinuvin 1130, 3 g of Addocat 201 and 20.33 g of a mixture of butyl acetate/MPA/xylene (1:1:1). After addition of a mixture of 15.91 g of preparation example 3 and 8.72 g of butyl acetate/xylene (1:1), the mixture was coated onto a black basecoat (Spiess Hecker, Permahyd®, Base Coat 280) and heated at 60° C. for 30 min for curing.

Example 5

[0168] 40.61 g of Setalux DA 870 BA were mixed with 0.21 g of BYK-141, 1.27 g of BYK-311, 0.84 g of Tinuvin 292, 1.69 g of Tinuvin 1130, 2.57 g of Addocat 201 and 21.42 g of a mixture of butyl acetate/MPA/xylene (1:1:1). After addition of a mixture of 13.63 g of preparation example 3, 14.29 g of the compound from preparation example 2 and 7.47 g of butyl acetate/xylene (1:1), the mixture was coated onto a black basecoat (Spiess Hecker, Permahyd®, Base Coat 280) and heated at 60° C. for 30 min for curing.

Use Examples

[0169] When adding STPs to 2K PU coating formulations, it was surprisingly observed that an extension of the pot life can be achieved. The addition of 10% by weight of an STP with various structures is sufficient for a 40%-70% increase in the pot life (table 1). This makes it possible to increase the processing time for a 2K PU formulation. In addition, an improved scratch resistance for the same gloss retention in weathering is observed (vide infra).

TABLE-US-00001 TABLE 1 Pot life extension of 2K PU systems compared to STP-containing 2K PU formulations. Catalyst: DBTL (0.1% by weight) used. Doubling of the viscosity at RT. No. Pot life (h) 1 2K PU (comparative example 4) 1.5 2 2K PU + 10% STP (example 5) 2.4

[0170] The addition of 10% by weight of an STP (based on the solids content) had a minor influence on the pendulum hardness of the coating film (table 2). The solvent resistances of the various 2K PU coating films with added STP correspond to those of the comparative system (No. 1). The gloss values (60° C.) gave values comparable to the comparative system. It was observed that the scratch resistance of the coating systems can be improved by addition of an STP.

TABLE-US-00002 TABLE 2 Scratch Scratch resistance resistance Solvent zero value final value Pendulum resistance Gloss Gloss hardness (Xy/MPA/ measurement measurement (s) EA/Ac)* (60°) (60°) Comparative 159 0 1 3 5 91.2 48.9 example 4 Example 5 115 0 2 3 5 91.0 60.5 *Xy = xylene, MPA = methoxypropyl acetate, EA = ethyl acetate, Ac = acetone

[0171] The addition of STPs to extend the pot life of a 2K PU formulation has no influence on the weathering resistance since the STP-containing clearcoats exhibit no changes whatsoever over a period of 1000 h in the CAM 180 test. This finding is confirmed by the gloss measurement at different angles before and after the weathering period.

TABLE-US-00003 TABLE 3 Weathering study (CAM 180) after 1000 h Gloss Gloss Visual measurement measurement inspection 0 h 1000 h (1000 h) (20°/ 60°) (20°/60°) Comparative No change 92/94 91/95 example 4 Example 5 No change 91/93 91/94