Crosslinkers for coating compounds

Abstract

The present invention describes new crosslinkers for coating compositions, their preparation, and their use.

Claims

1. A polyurethane of formula (IIa), formula (IIb), formula (IIc), or formula (V): ##STR00016## wherein: each R.sup.1 is 1,6-hexylene, ##STR00017## each X is oxygen (O) or sulfur (S); each n is a positive integer from 1 to 3; each R.sup.2 is an (n+1)-valent alkylene chain having 1 to 10 atoms and optionally interrupted by oxygen or nitrogen atoms; and each Block is a radical of a blocking agent (C) from which a hydrogen atom has been abstracted, wherein the blocking agent (C) is selected from the group consisting of: a secondary amine selected from the group consisting of a cyclic secondary amine, a di-C.sub.1-C.sub.10-alkylamine, and a di-C.sub.6-C.sub.12-cycloalkylamine; a lactam selected from the group consisting of 2-pyrrolidone and caprolactam; an oxime selected from the group consisting of an oxime of methyl n-amyl ketone, an oxime of methyl isoamyl ketone, an oxime of methyl 3-ethylheptyl ketone, an oxime of methyl 2,4-dimethylpentyl ketone, an oxime of butanone (methyl ethyl ketone), an oxime of cyclohexanone, an oxime of methyl isopropyl ketone, an oxime of methyl isobutyl ketone, an oxime of diisobutyl ketone, an oxime of methyl tert-butyl ketone, an oxime of diisopropyl ketone and an oxime of 2,2,6,6-tetramethylcyclohexanone; 3,5-dimethylpyrazole; a 1,2,4-triazole; and 1,3-dicarbonyl compound selected from the group consisting of acetylacetone, a malonic di-C.sub.1-C.sub.10 alkyl ester, and an acetoacetic di-C.sub.1-C.sub.10 alkyl ester.

2. The polyurethane according to claim 1, which is a compound of formula (IIa).

3. The polyurethane according to claim 2, wherein, in formula (IIa): R.sup.1 at each occurrence is 1,6-hexylene; and n is 1.

4. The polyurethane according to claim 1, which is a compound of formula (V).

5. The polyurethane according to claim 1, which has an NCO content of less than 7 wt %, calculated with a molar weight of 42 g/mol.

6. A coating composition, comprising at least one polyurethane according to claim 1; optionally a solvent; optionally typical coatings additives; and optionally at least one catalyst.

7. The coating composition according to claim 6, comprising the catalyst, wherein the catalyst comprises dibutyltin dilaurate, dioctyltin dilaurate, zinc(II) diacetate, zinc(II) dioctoate, zirconium acetylacetonate, zirconium 2,2,6,6-tetramethyl-3,5-heptanedionate, or bismuth compounds.

8. A process for preparing a polyurethane according to claim 1, the process comprising: subjecting hexamethylene 1,6-diisocyanate or isophorone diisocyanate to partial reaction with the blocking agent (C) and subsequently subjecting the remaining free isocyanate groups to at least partial reaction with a compound (B) of formula (I) ##STR00018## in which X, n, and R.sup.2 are as defined in claim 1.

9. A process for producing a polyurethane coating, the process comprising: applying at least one polyurethane according to claim 1, optionally mixed with at least one further polyisocyanate different from the polyurethane, to a substrate; and heating to a temperature at which at least some of the blocked isocyanate groups are cleaved significantly into free isocyanate groups and free blocking agent (C).

10. A one-component coating composition, comprising a polyurethane according to claim 1.

11. The polyurethane according to claim 1, having formula (lib), wherein: R.sup.1 at each occurrence is 1,6-hexylene, and n is 1.

12. The polyurethane according to claim 1, having formula (IIc), wherein: R.sup.1 at each occurrence is 1,6-hexylene; and n is 1.

Description

EXAMPLES

Raw Materials

(1) Basonat HI 100: polyisocyanate available commercially from BASF SE, Ludwigshafen, containing isocyanurate groups, based on hexamethylene 1,6-diisocyanate, and having an NCO content of 21.8% and a viscosity of 2800 mPa*s at 23 C.

Inventive Example

Example 1: Basonat HI+diisopropylamine+glycidol

(2) 404.6 g of Basonat HI 100 and 106.05 g of diisopropylamine were reacted in 252.15 g of butyl acetate. After about an hour at room temperature, the NCO content was 5.9%. Then 77.7 g of glycidol and 27 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 1600 mPas.

Comparative Example 1

(3) Product 1a: 143.3 g of Basonat HI 100 and 75.8 g of diisopropylamine were reacted in 93.9 g of butyl acetate. After 80 minutes at room temperature, the NCO content was 0.0%.

(4) Product 1b: 143.3 g of Basonat HI 100 and 55.00 g of glycidol were reacted in the presence of 50.3 g of butyl acetate and 27 ppm of dibutyltin dilaurate. After 80 minutes at 60 C., the NCO content was 0.0%.

(5) The two products were mixed, the mixing operation producing an inhomogeneous turbid solution.

Example 2

(6) 144.5 g of Basonat HI 100, 83.3 g of isophorone diisocyanate, and 75.8 g of diisopropylamine were reacted in 153.9 g of butyl acetate. After 20 minutes at room temperature, the NCO content was 7.1%. Then 55.5 g of glycidol and 27 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 1300 mPas.

Example 3

(7) 144.5 g of Basonat HI 100, 98.3 g of 1-isocyanato-4-[(4-isocyanatocyclohexyl)methyl] cyclohexane (H12MDI), and 75.8 g of diisopropylamine were reacted in 160.3 g of butyl acetate. After 20 minutes at room temperature, the NCO content was 6.8%. Then 55.5 g of glycidol and 27 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 1640 mPas at 23 C.

Example 4

(8) 202.3 g of Basonat HI 100, 45.7 g of N-methylbutylamine were reacted in 122.9 g of butyl acetate. After 20 minutes at room temperature, the NCO content was 6.0%. Then 38.9 g of glycidol and 56 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 2100 mPas at 23 C.

Example 5

(9) 404.6 g of Basonat HI 100, 92.4 g of 2-butanone oxime were reacted in 245.9 g of butyl acetate. After 20 minutes at room temperature, the NCO content was 6.0%. Then 77.7 g of glycidol and 28 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 2100 mPas at 23 C.

Example 6

(10) 404.6 g of Basonat HI 100, 100.8 g of 3,5-dimethylpyrazole were reacted in 249.9 g of butyl acetate. After 20 minutes at room temperature, the NCO content was 6.0%. Then 77.7 g of glycidol and 28 ppm of dibutyltin dilaurate were added. After about 6 hours at 60 C., the NCO content was 0.0%. The corresponding product had a viscosity of 2100 mPas at 23 C.

Example 7

(11) 144.5 g of Basonat HI 100 and 50.5 g of diisopropylamine were reacted in 105.4 g of butyl acetate. After 30 minutes at room temperature, the NCO content was 3.1%. The mixture was subsequently allowed to react with 51.0 g of glycerol diglycidyl ether at 60 C.

(12) Tests:

(13) For the measurement of the pendulum damping, the samples were applied in a wet film thickness of 400 m to glass plates, evaporated at room temperature for 15 minutes, and cured at the temperature and time indicated in the table.

(14) The pendulum damping was measured in accordance with DIN 53157, with high values denoting high hardness. The FIGURE reported is the mean of three measurements.

(15) TABLE-US-00001 Curing Pendulum damping Composition Temp. Time Swings Example 1 110 C. 30 min 2 60 min 2 120 min 4 130 C. 30 min 5 60 min 16 120 min 55 150 C. 30 min 7 60 min 113 120 min 122 Example 2 110 C. 30 min 26 60 min 26 120 min 57 130 C. 30 min 38 60 min 85 120 min 117 150 C. 30 min 49 60 min 133 120 min 130 Example 3 110 C. 30 min 21 60 min 35 120 min 65 130 C. 30 min 62 60 min 74 120 min 120 150 C. 30 min 66 60 min 130 120 min 121 Example 4 110 C. 30 min 2 60 min 4 120 min 12 130 C. 30 min 10 60 min 23 120 min 44 150 C. 30 min 15 60 min 26 120 min 45

Application Example

(16) The coating composition from example 1 was cured repeatedly with different catalysts (0.5 wt % catalyst).

(17) TABLE-US-00002 Curing Pendulum damping Catalyst Temp. Time Swings No catalyst 130 C. 120 min 56 1,4-Diazabicyclo[2.2.2]octane 130 C. 120 min 131 (TEDA) Tin 2-ethylhexanoate 130 C. 120 min 97 Aluminum tributylate 130 C. 120 min 72 Imidazole 130 C. 120 min 125