COLOUR-STABLE CURING COMPOSITIONS CONTAINING POLYISOCYANATES OF (CYCLO)ALIPHATIC DIISOCYANATES

Abstract

The present invention relates to novel color drift-stable compositions of polyisocyanates of (cyclo)aliphatic diisocyanates.

Claims

1. A polyisocyanate composition comprising (A) at least one polyisocyanate obtained by reacting at least one monomeric (cyclo)aliphatic isocyanate, wherein the at least one polyisocyanate has an NCO content of at least 15% by weight, (B) at least one silyl ester selected from the group of silyl phosphates and silyl phosphonates in an amount of 0.2 to 300 ppm by weight, based on component (A), (C) at least one sterically hindered phenol, (D) at least one Lewis-acidic organic metal compound capable of accelerating the reaction of isocyanate groups with isocyanate-reactive groups, (E) at least one solvent, (F) optionally at least one further antioxidant, and (G) optionally other coatings additives.

2. The polyisocyanate composition according to claim 1, wherein the at least one silyl ester (B) is a silyl phosphate.

3. The polyisocyanate composition according to claim 1, wherein the at least one silyl ester (B) is a tris(silyl) phosphate.

4. The polyisocyanate composition according to claim 1, wherein the at least one silyl ester (B) is present in an amount of 10 to 300 ppm by weight, based on component (A).

5. The polyisocyanate composition according to claim 1, wherein the at least one (cyclo)aliphatic isocyanate is selected from the group consisting of hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4-di(isocyanatocyclohexyl)methane and 2,4-di(isocyanatocyclohexyl)methane.

6. The polyisocyanate composition according to claim 1, wherein the at least one polyisocyanate (A) has been prepared using a catalyst based on ammonium carboxylate, ammonium a-hydroxyalkylcarboxylate or ammonium hydroxide.

7. The polyisocyanate composition according to claim 1, wherein the at least one sterically hindered phenol (C) has exactly one phenolic hydroxyl group per aromatic ring, and wherein at least one ortho position, relative to the phenolic hydroxyl group, bears an optionally substituted tert-butyl group.

8. The polyisocyanate composition according to claim 1, wherein the at least one Lewis-acidic organic metal compound (D) comprises a metal selected from the group consisting of tin, zinc, titanium, zirconium and bismuth.

9. The polyisocyanate composition according to claim 1, wherein the weight ratio of the at least one polyisocyanate (A) to the at least one solvent (E) is 9:1 to 2:8.

10. The polyisocyanate composition according to claim 1, wherein the at least one solvent (E) is selected from the group consisting of aromatic hydrocarbons, (cyclo)aliphatic hydrocarbons, ketones, esters, ethers, ether esters and carbonates.

11. The polyisocyanate composition according to claim 1, wherein the at least one further antioxidant (F) is present and is selected from the group of phosphites, phosphonates, phosphonites and thioethers.

12. A process for stabilizing polyisocyanate compositions according to claim 1, the process comprising: adding at least one silyl ester (B) in an amount of 0.2 to 300 ppm by weight based on component (A), at least one sterically hindered phenol (C), at least one Lewis-acidic organic metal compound (D), at least one solvent (E), optionally at least one further antioxidant (F) and optionally other coatings components (G) to the at least one polyisocyanate (A).

13. A process for producing polyurethane coatings, comprising: reacting a polyisocyanate composition according to claim 1 with at least one binder comprising isocyanate-reactive groups.

14. A process for producing polyurethane coatings, comprising: reacting a polyisocyanate composition according to claim 1 with at least one binder selected from the group consisting of polyacrylate polyols, polyester polyols, polyether polyols, polyurethane polyols, polyurea polyols, polyetherols, polycarbonates, polyester polyacrylate polyols, polyester polyurethane polyols, polyurethane polyacrylate polyols, polyurethane-modified alkyd resins, fatty acid-modified polyester polyurethane polyols, copolymers with allyl ethers and copolymers or graft polymers thereof.

15. A process, comprising employing a polyisocyanate composition according to claim 1 as curing agent in coating materials in primers, primer surfacers, pigmented topcoats, basecoats and clearcoats in the sectors of automotive refinishing or large vehicle finishing, or in utility vehicles in the agricultural and construction sector.

Description

EXAMPLES

Feedstocks:

[0204] Polyisocyanates (A): isocyanurate based on hexamethylene diisocyanate

Polyisocyanate (A1), Polyisocyanurate:

[0205] Hexamethylene diisocyanate HDI was converted in the presence of 80 ppm of benzyltrimethylammonium hydroxyisobutyrate as catalyst based on hexamethylene diisocyanate, 60% in ethylene glycol, in a multistage reactor cascade at 115, 120 and 130 C. Hexamethylene diisocyanate was distilled off in a multistage process with HDI recycling. NCO content of the product: 22.2%, viscosity: 2675 mPa*s

Polyisocyanate (A2), Polyisocyanurate:

[0206] Hexamethylene diisocyanate HDI was converted in the presence of 87 ppm of benzyltrimethylammonium hydroxyisobutyrate as catalyst based on hexamethylene diisocyanate, 5% in 2-ethylhexanol, in a multistage reactor cascade at 120 C. Hexamethylene diisocyanate was distilled off in a multistage process with HDI recycling. NCO content of the product: 22.1%, viscosity: 2750 mPa*s.

Polyisocyanate (A3): Isocyanurate Based on Hexamethylene Diisocyanate

[0207] Basonat HI 100 (BASF SE): NCO content of the product: 22.0%, viscosity about 2900 mPa*s.

Polyisocyanate (A4): Isocyanurate Based on Hexamethylene Diisocyanate:

[0208] Hexamethylene diisocyanate HDI was converted in the presence of 66 ppm of benzyltrimethylammonium hydroxyisobutyrate as catalyst based on hexamethylene diisocyanate, 5% in 2-ethylhexanol, in a multistage reactor cascade at 100, 120 and 140 C. Termination was by thermal means at 140 C. Hexamethylene diisocyanate was distilled off in a multistage process with HDI recycling. NCO content of the product: 22.2%, viscosity: 2580 mPa*s.

TABLE-US-00001 Silyl derivatives: Tris(trimethylsilyl) phosphate from Sigma-Aldrich. - inventive trimethylsilyl trifluoroacetate from Sigma-Aldrich. - noninventive N,O-Bis(trimethylsilyl)acetamide from Sigma-Aldrich. - noninventive 1,3-Bis(trimethylsilyl)urea from Sigma-Aldrich. - noninventive hexamethyldisilazane from Sigma-Aldrich. - noninventive Sterically hindered phenols (C): Irganox 1010: pentaerythritol tetrakis(3-(3,5- di-tert-butyl-4-hydroxyphenyl)- propionate, from BASF SE Irganox 1076: octadecyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, from BASF SE Irganox 1135: isooctyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate; from BASF SE Lewis-acidic catalysts (D): DBTL dibutyltin dilaurate (DBTL): from Sigma-Aldrich Solvents (E): Solvent Naphtha (boiling range about 170-180 C.) Methyl amyl ketone from Sigma-Aldrich Secondary antioxidants (F): Triphenyl phosphite from Alfa Aesar Tributyl phosphite from Sigma-Aldrich Irgafos OPH from BASF SE

Storage Tests:

[0209] The polyisocyanates (A) were stored under nitrogen in 50% by weight solutions in solvent (E) (1:1 in % by weight) with the concentrations specified in the experiments of silyl ester (B), Lewis acid catalysts (D), optionally sterically hindered phenols (C), optionally further additives, in firmly closed screwtop vessels (25 g in 30 mL vessels) at 50 C. air circulation ovens for exclusion of air. Traces of air are not ruled out.

[0210] Storage test 1: 50% polyisocyanate (A), 50% Solvesso 100, 1000 ppm by weight of dibutyltin dilaurate based on polyisocyanate

[0211] Storage test 2: 50% polyisocyanate (A), 50% methyl amyl ketone, 1000 ppm by weight of dibutyltin dilaurate based on polyisocyanate

[0212] The concentrations of the compounds (B), (C), (D), (F) in ppm by weight, in the respectively undiluted state of the compounds (B), (C), (D), (F), relate to the total amount of polyisocyanate (A).

[0213] Color numbers are measured directly (immediately prior to commencement of storage) and after storage of the different periods of time. The color number is measured in APHA to DIN EN 1557 on a Lico 150 from Lange in a 5 cm analytical cuvette having a volume of 5 mL. Error tolerances for the target value are 20 Hz (+/5, actual value 18 Hz); target value 102 Hz (+/10, actual value 99 Hz); target value 202 Hz (+/20, actual value 197 Hz). Color numbers are measured directly (immediately prior to commencement of storage), after storage after 7; 28; 70 and optionally after 105 days. The lower the color numbers the better.

[0214] Storage test 1: 50% polyisocyanate, 50% Solvesso 100, 1000 ppm

[0215] DBTL/polyisocyanate

[0216] Series 1 in storage test 1 for color number drift of a solution consisting of 50% polyisocyanate A, 50% Solvesso 100, 1000 ppm DBTL/polyisocyanate:

TABLE-US-00002 Series 1: polyisocyanate (A1): storage test 1 (Solvesso 100, DBTL) d/Hz Additive (ppm) 0 7 28 70 V1 200 Irganox 1135 + 200 tributyl 12 38 64 340 phosphite B1 200 Irganox 1135 + 200 tributyl 12 18 39 108 phosphite + 100 tris(trimethylsilyl) phosphate V2 200 Irganox 1010 + 200 triphenyl 11 57 84 340 phosphite B2 200 Irganox 1010 + 200 triphenyl 11 50 91 83 phosphite + 100 tris(trimethylsilyl) phosphate V3 200 Irganox 1135 + 200 triphenyl 14 70 81 174 phosphite V4 200 Irganox 1135 + 200 triphenyl 14 52 172 395 phosphite + 100 N,O- bis(trimethylsilyl)acetamide V5 200 Irganox 1135 + 200 triphenyl 14 76 94 240 phosphite + 100 1,3-bis(trimethylsilyl)urea V6 200 Irganox 1135 + 200 triphenyl 14 57 143 353 phosphite + 100 hexamethyldisilazane B3 200 Irganox 1135 + 200 triphenyl 14 58 83 85 phosphite + 100 tris(trimethylsilyl) phosphate V7 200 Irganox 1010 + 200 Irgafos OPH 11 83 63 359 B4 200 Irganox 1010 + 200 ppm Irgafos 11 37 82 81 OPH + 100 tris(trimethylsilyl) phosphate V8 200 Irganox 1076 + 200 Irgafos OPH 12 83 65 357 B5 200 Irganox 1076 + 200 Irgafos OPH + 12 41 87 121 100 tris(trimethylsilyl) phosphate V9 200 Irganox 1135 + 200 Irgafos OPH 17 42 113 233 V10 200 Irganox 1135 + 200 Irgafos OPH + 17 80 187 379 100 N,O-bis(trimethylsilyl)acetamide V11 200 Irganox 1135 + 200 Irgafos OPH + 17 43 119 270 100 1,3-bis(trimethylsilyl)urea V12 200 Irganox 1135 + 200 Irgafos OPH + 17 80 184 369 100 hexamethyldisilazane B6 200 Irganox 1135 + 200 Irgafos OPH + 17 34 36 69 100 tris(trimethylsilyl) phosphate Result: Tris(trimethylsilyl) phosphate improves color drift stability in conjunction with phenolic antioxidants (C), optionally with a further antioxidant (F), including over the combination of phenol/phosphite (cf. WO 2005/089085) and phenol/phosphonate (Irgafos OPH; cf. WO 2008/116894). Tris(trimethylsilyl) phosphate is the only effective trimethylsilyl-based additive in the examples. N,O-Bis(trimethylsilyl)acetamide; 1,3-bis(trimethylsilyl)urea; and hexamethyldisilazane are worse [cf. EP 1833785 B1/US 8552137 B2].

TABLE-US-00003 Series 2: polyisocyanate (A2): storage test 1 (Solvesso 100, DBTL) d/Hz Additive (ppm) 0 7 28 70 V13 200 Irganox 1135 + 200 Irgafos 10 39 63 141 OPH V14 200 Irganox 1135 + 200 Irgafos 9 42 64 139 OPH + 50 trimethylsilyl trifluoroacetate V15 200 Irganox 1135 + 200 Irgafos 8 44 71 174 OPH + 100 trimethylsilyl trifluoroacetate V16 200 Irganox 1135 + 200 Irgafos 10 36 57 126 OPH + 50 tetrakis(trimethylsilyloxy)silane V17 200 Irganox 1135 + 200 Irgafos 10 31 53 154 OPH + 100 tetrakis(trimethylsilyloxy)silane B7 200 Irganox 1135 + 200 Irgafos 10 12 15 14 OPH + 50 tris(trimethylsilyl) phosphate B8 200 Irganox 1135 + 200 Irgafos 10 10 15 14 OPH + 100 tris(trimethylsilyl) phosphate Result: Tris(trimethylsilyl) phosphate is the only effective trimethylsilyl-based additive

TABLE-US-00004 Series 3: polyisocyanate (A4): storage test 1 (Solvesso 100, DBTL) d/Hz Additive (ppm) 0 7 28 70 V18 200 Irganox 1135 + 200 Irgafos 17 22 43 116 OPH B9 200 Irganox 1135 + 200 Irgafos 17 21 25 28 OPH + 100 tris(trimethylsilyl) phosphate Result: Color drift with tris(trimethylsilyl) phosphate is significantly lower.

[0217] Storage test 2: 50% polyisocyanate, 50% methyl amyl ketone, 1000 ppm

[0218] DBTL/polyisocyanate

[0219] The following storage tests were tested in the storage test 2 formulation with methyl amyl ketone and DBTL.

TABLE-US-00005 Series 4: polyisocyanate (A1): storage test 2 d/Hz Additive (ppm) 0 7 28 70 105 V19 100 tris(trimethylsilyl) phosphate 22 43 72 106 143 V20 200 triphenyl phosphite 26 37 62 84 117 V21 200 triphenyl phosphite + 100 21 38 65 105 138 tris(trimethylsilyl) phosphate V22 200 Irgafos OPH 27 40 68 97 160 V23 200 Irgafos OPH + 100 25 38 65 107 141 tris(trimethylsilyl) phosphate V24 200 Irganox 1135 27 35 55 88 116 B10 200 Irganox 1135 + 100 22 34 39 49 54 tris(trimethylsilyl) phosphate V25 200 Irganox 1135 + 200 tributyl 17 27 66 141 209 phosphite B11 200 Irganox 1135 + 200 tributyl 18 18 24 36 43 phosphite + 100 tris(trimethylsilyl) phosphate V26 200 Irganox 1010 + 200 triphenyl 20 15 58 108 157 phosphite B12 200 Irganox 1010 + 200 triphenyl 20 24 24 40 54 phosphite + 100 tris(trimethylsilyl) phosphate V27 200 Irganox 1076 + 200 triphenyl 19 21 62 112 193 phosphite B13 200 Irganox 1076 + 200 triphenyl 19 20 32 39 48 phosphite + 100 tris(trimethylsilyl) phosphate V28 200 Irganox 1135 + 200 triphenyl 17 19 56 112 174 phosphite B14 200 Irganox 1135 + 200 triphenyl 17 24 27 42 49 phosphite + 50 tris(trimethylsilyl) phosphate B15 200 Irganox 1135 + 200 triphenyl 17 21 25 44 51 phosphite + 100 tris(trimethylsilyl) phosphate V29 200 Irganox 1010 + 200 Irgafos 20 19 43 111 186 OPH B16 200 Irganox 1010 + 200 ppm 20 22 30 39 48 Irgafos OPH + 100 tris(trimethylsilyl) phosphate V30 200 Irganox 1076 + 200 Irgafos 20 22 51 95 155 OPH B17 200 Irganox 1076 + 200 Irgafos 20 20 29 41 48 OPH + 100 tris(trimethylsilyl) phosphate V31 200 Irganox 1135 + 200 Irgafos 17 28 48 129 198 OPH B18 200 Irganox 1135 + 200 Irgafos 17 30 58 111 143 OPH + 1 ppm tris(trimethylsilyl) phosphate B19 200 Irganox 1135 + 200 Irgafos 17 16 43 90 117 OPH + 5 ppm tris(trimethylsilyl) phosphate B20 200 Irganox 1135 + 200 Irgafos 17 15 24 89 115 OPH + 10 ppm tris(trimethylsilyl) phosphate B21 200 Irganox 1135 + 200 Irgafos 17 17 19 76 110 OPH + 20 ppm tris(trimethylsilyl) phosphate B22 200 Irganox 1135 + 200 Irgafos 17 18 14 22 21 OPH + 50 ppm tris(trimethylsilyl) phosphate B23 200 Irganox 1135 + 200 Irgafos 17 16 22 22 17 OPH + 100 ppm tris(trimethylsilyl) phosphate V32 200 Irganox 1135 + 200 Irgafos 17 23 21 31 31 OPH + 300 ppm tris(trimethylsilyl) slighty cloudy phosphate V33 200 Irganox 1135 + 200 Irgafos highly cloudy OPH + 1000 ppm tris(trimethylsilyl) phosphate Result: Tris(trimethylsilyl) phosphate improves color drift stability in conjunction with phenolic antioxidants (C), optionally with a further antioxidant (F). Color number drift is not improved without phenolic antioxidant. In the range from 1 to 100 ppm tris(trimethylsilyl) phosphate there are clear solutions with low color drift, at 300 ppm slight haze with low color drift, at 1000 ppm tris(trimethylsilyl) phosphate significant haze.

TABLE-US-00006 Series 5: polyisocyanate (A3): storage test 2 (methyl amyl ketone, DBTL) d/Hz Additive (ppm) 0 7 28 70 105 V34 none 13 30 60 85 109 V35 50 tris(trimethylsilyl) phosphate 12 35 72 102 133 V36 100 tris(trimethylsilyl) phosphate 12 34 70 100 132 V37 200 triphenyl phosphite 12 34 62 83 120 V38 200 triphenyl phosphite + 100 12 28 62 96 124 tris(trimethylsilyl) phosphate V39 200 Irgafos OPH 12 35 70 94 186 V40 200 Irgafos OPH + 100 12 32 70 102 133 tris(trimethylsilyl) phosphate V41 200 Irganox 1135 12 30 46 79 116 B24 200 Irganox 1135 + 100 12 16 29 33 35 tris(trimethylsilyl) phosphate V42 200 Irganox 1135 + 200 tributyl 10 25 43 88 110 phosphite B25 200 Irganox. 1135 + 200 tributyl 10 18 22 31 34 phosphite + 100 tris(trimethylsilyl) phosphate V43 200 Irganox 1010 + 200 triphenyl 11 26 41 86 108 phosphite B26 200 Irganox 1010 + 200 triphenyl 11 18 23 33 46 phosphite + 100 tris(trimethylsilyl) phosphate V44 200 Irganox 1135 + 200 triphenyl 10 26 42 87 111 phosphite B27 200 Irganox 1135 + 200 triphenyl 10 16 20 33 25 phosphite + 50 tris(trimethylsilyl) phosphate B28 200 Irganox 1135 + 200 triphenyl 10 16 21 25 27 phosphite + 100 tris(trimethylsilyl) phosphate B29 200 Irganox 1135 + 200 triphenyl 10 18 22 31 28 phosphite + 300 tris(trimethylsilyl) phosphate V45 200 Irganox 1135 + 200 triphenyl highly cloudy phosphite + 1000 tris(trimethylsilyl) phosphate V46 200 Irganox 1076 + 200 Irgafos 9 21 33 72 159 OPH B30 200 Irganox 1076 + 200 Irgafos 9 19 17 23 31 OPH + 100 tris(trimethylsilyl) phosphate V47 200 Irganox 1135 + 200 Irgafos 17 30 42 98 195 OPH B31 200 Irganox 1135 + 200 Irgafos 17 23 26 84 109 OPH + 1 tris(trimethylsilyl) phosphate B32 200 Irganox 1135 + 200 Irgafos 17 19 23 82 111 OPH + 5 tris(trimethylsilyl) phosphate B33 200 Irganox 1135 + 200 Irgafos 17 20 25 44 47 OPH + 10 tris(trimethylsilyl) phosphate B34 200 Irganox 1135 + 200 Irgafos 17 19 21 39 43 OPH + 20 tris(trimethylsilyl) phosphate B35 200 Irganox 1135 + 200 Irgafos 17 18 22 39 42 OPH + 50 tris(trimethylsilyl) phosphate B36 200 Irganox 1135 + 200 Irgafos 17 17 21 31 38 OPH + 100 tris(trimethylsilyl) phosphate B37 200 Irganox 1135 + 200 Irgafos 17 19 23 39 40 OPH + 300 tris(trimethylsilyl) phosphate V48 200 Irganox 1135 + 200 Irgafos highly cloudy OPH + 1000 tris(trimethylsilyl) phosphate Result: Tris(trimethylsilyl) phosphate improves color drift stability in conjunction with phenolic antioxidants (C), optionally with a further antioxidant (F). Color number drift is not improved without phenolic antioxidant. In the range from 1 to 300 ppm tris(trimethylsilyl) phosphate there are clear solutions with low color drift; at 1000 ppm tris(trimethylsilyl) phosphate there is significant cloudiness.