Method for producing polyisocyanates of (cyclo)aliphatic diisocyanates which are flocculation-stable in solvents

Abstract

The present invention relates to a new process for preparing polyisocyanates containing isocyanurate groups and being flocculation-stable in solvents from (cyclo)aliphatic diisocyanates.

Claims

1. A method for reducing flocculation and/or precipitation in a polyisocyanate mixture which comprises at least one solvent (C) and at least one polyisocyanate (A) comprising a polyisocyanurate based on hexamethylene diisocyanate, the method comprising adding, to the polyisocyanate mixture, tristrimethylsilyl phosphate, in an amount of 10 to 100 ppm by weight based on the at least one polyisocyanate (A), to obtain a polyisocyanate mixture comprising the tristrimethylsilyl phosphate.

2. The method of claim 1, wherein the tristrimethylsilyl phosphate is used substoichiometrically in relation to an amount of water present in the polyisocyanate mixture.

3. The method of claim 1, wherein the at least one polyisocyanate (A) has an NCO content of at least 15% by weight.

4. The method of claim 1, wherein the polyisocyanate mixture comprising the tristrimethylsilyl phosphate further comprises at least one phenol or bridged bisphenol which has exactly one phenolic hydroxyl group on each aromatic ring and has alkyl groups in the positions ortho to each phenolic hydroxyl group.

5. The method of claim 1, wherein the polyisocyanate mixture comprising the tristrimethylsilyl phosphate further comprises at least one Lewis acid.

6. The method of claim 1, wherein the polyisocyanate mixture comprises at least one antioxidant selected from the group consisting of sterically hindered phenols, phosphonites, and phosphonates.

7. A method for stabilizing a polyisocyanate mixture which comprises at least one solvent (C) and at least one polyisocyanate (A) comprising a polyisocyanurate based on hexamethylene diisocyanate against flocculation during storage, the method comprising admixing the polyisocyanate mixture with tristrimethylsilyl phosphate, in an amount of 10 to 100 ppm by weight based on the at least one polyisocyanate (A).

8. The method of claim 7, wherein the polyisocyanate mixture comprises at least one Lewis acid.

9. A method for coating a substrate with a polyisocyanate mixture which comprises at least one polyisocyanate (A) comprising a polyisocyanurate based on hexamethylene diisocyanate and is stabilized against flocculation during storage in a solvent, the method comprising: admixing the polyisocyanate mixture with tristrimethylsilyl phosphate, in an amount of 10 to 100 ppm by weight based on the at least one polyisocyanate (A), to obtain a mixture; admixing the mixture with at least one solvent (C) and optionally other additives, to obtain a composition; storing the composition, to obtain a stored composition; subsequently admixing the stored composition with at least one binder-comprising component, to obtain an admixed composition; and subsequently applying the admixed composition to a substrate.

10. The method of claim 9, wherein the at least one binder-comprising component comprises a polymer selected from the group consisting of a polyacrylate polyol, a polyester polyol, a polyurethane polyol, a polycarbonate polyol and a polyether polyol.

Description

EXAMPLES

(1) Ingredients:

(2) Polyisocyanates (A): isocyanurate based on hexamethylene diisocyanate

(3) Polyisocyanate (A1), polyisocyanurate based on hexamethylene diisocyanate: Hexamethylene diisocyanate HDI was reacted in the presence of 80 ppm by weight of benzyltrimethylammonium hydroxyisobutyrate as catalyst, based on hexamethylene diisocyanate, at 60% strength in ethylene glycol, in a multi-stage reactor cascade at 115, 120 and 130° C. Hexamethylene diisocyanate was distilled off in a multistage process with HDI recirculation. NCO content of the product: 22.2%, viscosity: 2675 mPa*s.

(4) Polyisocyanate (A2): polyisocyanurate based on hexamethylene diisocyanate Basonat HI 100 BASF SE

(5) Silyl Derivatives:

(6) TABLE-US-00001 Tristrimethylsilyl phosphate Sigma-Aldrich inventive N,O-bis(trimethylsilyl) acetamide Sigma-Aldrich not inventive 1,3-bis(trimethylsilyl)urea Sigma-Aldrich not inventive Hexamethyldisilazane Sigma-Aldrich not inventive
Solvents (C):

(7) Xylene

(8) Butyl acetate

(9) Sterically Hindered Phenols:

(10) Irganox® 1010: pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), BASF SE Irganox® 1076: octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), BASF SE Irganox® 1135: isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), BASF SE
Secondary Antioxidants:

(11) TABLE-US-00002 Irgafos OPH BASF SE Triphenyl phosphite Alfa Aesar Tributyl phosphite Sigma-Aldrich
Storage Test:

(12) For determining the flocculation stability, mixtures consisting of 30% polyisocyanate and 70% xylene/butyl acetate=2:1, containing 400 ppm of water to solvent mixture, were prepared. Additives were incorporated via the solvents. 50 g of the mixture was rendered inert by the passage of nitrogen over it in 50 mL screw lid vessels without writing on the side, which were then firmly closed and stored at 23° C.±5° C./(50%±10% atmospheric humidity) in a climatic chamber. The flocculation was assessed by inspection daily on weekdays in the first two weeks, after three weeks, from four weeks onward, at two-week intervals.

(13) To assess the flocculation stability, a report is made of the first day on which one of the two following flocculation stages is achieved:

(14) 1 Slight flocculation: weakly apparent. For better recognition of turbidity, apparently clear solutions are briefly slightly horizontally rotated in a circle. In some cases slight flocculation is then evident better as a tail.

(15) 2 Severe flocculation, readily apparent, sedimentation, discontinuation of the study.

(16) Although the flocculation is determined by experienced personnel, a certain standard deviation is nevertheless present, as a consequence of slight differences in conditions (e.g., exact amount of water in the solvent, etc.) and in the visual determination of slight and severe turbidity. In different series there may be slightly different results for specimens with “the same” composition, but in terms of the number of days these specimens are nevertheless all comparable, and are much lower in the proportion of good examples to poor references.

(17) The day values for the two flocculation stages are additionally added up for a better comparison. The greater the number of day values or the total thereof, the better the flocculation stability. At 210 days of measurement, measurement is terminated automatically.

(18) Series 1: Polyisocyanate (A1): Flocculation Times in Days after a Maximum of 210 Days of Measurement

(19) TABLE-US-00003 Fl./d Additive (ppm) 1 2 Total C1 200 Irganox 1135 28 28 56 I1 200 Irganox 1135 + 84 196 280 100 tristrimethylsilyl phosphate C2 200 triphenyl phosphite 2 98 100 I2 200 triphenyl phosphite + 84 210 294 100 tristrimethylsilyl phosphate C3 200 Irganox 1076 + 200 triphenyl phosphite 12 21 33 I3 200 Irganox 1076 + 200 triphenyl 12 210 222 phosphite + 100 tristrimethylsilyl phosphate C4 200 Irganox 1135 + 200 triphenyl phosphite 6 28 34 I4 200 Irganox 1135 + 200 triphenyl 126 210 336 phosphite + 50 tristrimethylsilyl phosphate I5 200 Irganox 1135 + 200 triphenyl 84 210 294 phosphite + 100 tristrimethylsilyl phosphate C5 200 Irganox 1076 + 200 Irgafos OPH 28 28 56 I6 200 Irganox 1076 + 200 Irgafos OPH + 56 182 238 100 tristrimethylsilyl phosphate C6 200 Irganox 1010 + 200 Irgafos OPH 42 42 84 I7 200 Irganox 1010 + 200 ppm Irgafos 84 210 294 OPH + 100 tristrimethylsilyl phosphate

(20) Result: Tristrimethylsilyl phosphate improves the flocculation in combination with at least one respective antioxidant.

(21) Series 2: Polyisocyanate (A2): Flocculation Times in Days after a Maximum of 210 Days of Measurement

(22) TABLE-US-00004 Fl./d Additive (ppm) 1 2 Total C7 none 11 21 32 I8 50 tristrimethylsilyl phosphate 56 210 266 I9 100 tristrimethylsilyl phosphate 28 210 238 C8 200 Irganox 1135 8 21 29 I10 200 Irganox 1135 + 28 210 238 100 tristrimethylsilyl phosphate C9 200 triphenyl phosphite 14 21 35 I11 200 triphenyl phosphite + 56 154 210 100 tristrimethylsilyl phosphate C10 200 Irgafos OPH 21 21 42 I12 200 Irgafos OPH + 56 210 266 100 tristrimethylsilyl phosphate C11 200 Irganox 1135 + 200 tributyl phosphite 21 21 42 I13 200 Irganox 1135 + 200 tributyl phosphite + 13 210 223 100 tristrimethylsilyl phosphate C12 200 Irganox 1010 + 200 triphenyl phosphite 28 42 70 I14 200 Irganox 1010 + 200 triphenyl 28 196 224 phosphite + 100 tristrimethylsilyl phosphate C13 200 Irganox 1076 + 200 triphenyl phosphite 12 42 54 I15 200 Irganox 1076 + 200 triphenyl 9 126 135 phosphite + 100 tristrimethylsilyl phosphate C14 200 Irganox 1135 + 200 triphenyl phosphite 8 21 29 I16 200 Irganox 1135 + 200 triphenyl phosphite + 8 210 218 50 tristrimethylsilyl phosphate C15 200 Irganox 1135 + 200 triphenyl phosphite + 7 8 15 300 tristrimethylsilyl phosphate C16 200 Irganox 1135 + 200 triphenyl phosphite + 5 5 10 1000 tristrimethylsilyl phosphate

(23) Result: (50 and) 100 ppm of tristrimethylsilyl phosphate improve the flocculation without antioxidant, with one respective antioxidant, and with two respective antioxidants.

(24) 300 and 1000 ppm of tristrimethylsilyl phosphate have adverse effects in combination with 200 Irganox® 1135+200 triphenyl phosphite.

(25) Series 3: Polyisocyanate (A1): Flocculation Times in Days after a Maximum of 126 Days of Measurement (Termination Owing to Flocculation)

(26) TABLE-US-00005 Fl./d Additives (ppm) 1 2 Total C17 200 Irganox 1135 + 200 Irgafos OPH 21 21 42 C18 200 Irganox 1135 + 200 Irgafos 5 13 18 OPH + 100 N,O- bis(trimethylsilyl)acetamide C19 200 Irganox 1135 + 200 Irgafos 9 13 22 OPH + 100 1,3- bis(trimethylsilyl)urea C20 200 Irganox 1135 + 200 Irgafos 9 13 22 OPH + 100 hexamethyldisilazane I17 200 Irganox 1135 + 200 Irgafos 12 126 138 OPH + 100 tristrimethylsilyl phosphate

(27) Result: 100 ppm of tristrimethylsilyl phosphate improve the flocculation; N,O-bis(trimethylsilyl)acetamide, hexamethyldisilazane, and 1,3-bis(trimethylsilyl)urea do not.

(28) Series 4: Polyisocyanate (A1): Flocculation Times in Days after a Maximum of 210 Days of Measurement

(29) TABLE-US-00006 Fl./d Additives (ppm) 1 2 Total C21 200 Irganox 1135 + 200 Irgafos OPH 7 14 21 C22 200 Irganox 1135 + 200 Irgafos 7 11 18 OPH + 1 tristrimethylsilyl phosphate I18 200 Irganox 1135 + 200 Irgafos 14 56 70 OPH + 5 tristrimethylsilyl phosphate I19 200 Irganox 1135 + 200 Irgafos 126 210 336 OPH + 10 tristrimethylsilyl phosphate I20 200 Irganox 1135 + 200 Irgafos 14 210 224 OPH + 20 tristrimethylsilyl phosphate I21 200 Irganox 1135 + 200 Irgafos 14 182 196 OPH + 50 tristrimethylsilyl phosphate I22 200 Irganox 1135 + 200 Irgafos 2 182 184 OPH + 100 tristrimethylsilyl phosphate C23 200 Irganox 1135 + 200 Irgafos 2 9 11 OPH + 300 tristrimethylsilyl phosphate C24 200 Irganox 1135 + 200 Irgafos 2 7 9 OPH + 1000 tristrimethylsilyl phosphate

(30) Result: 5 ppm of tristrimethylsilyl phosphate improve flocculation slightly, 10, 20, 50 and 100 ppm of tristrimethylsilyl phosphate do so very significantly. 300 and 1000 ppm have nonpositive or negative effects.

(31) Series 5: Polyisocyanate (A2): Flocculation Times in Days after a Maximum of 210 Days of Measurement

(32) TABLE-US-00007 Fl./d Additives (ppm) 1 2 Total C25 200 Irganox 1135 + 200 Irgafos OPH 7 21 28 I23 200 Irganox 1135 + 200 Irgafos 7 56 63 OPH + 1 tristrimethylsilyl phosphate I24 200 Irganox 1135 + 200 Irgafos 56 210 266 OPH + 5 tristrimethylsilyl phosphate I25 200 Irganox 1135 + 200 Irgafos 21 210 231 OPH + 10 tristrimethylsilyl phosphate I26 200 Irganox 1135 + 200 Irgafos 21 210 231 OPH + 20 tristrimethylsilyl phosphate I27 200 Irganox 1135 + 200 Irgafos 7 210 217 OPH + 50 tristrimethylsilyl phosphate I28 200 Irganox 1135 + 200 Irgafos 7 210 217 OPH + 100 tristrimethylsilyl phosphate C26 200 Irganox 1135 + 200 Irgafos 7 8 15 OPH + 300 tristrimethylsilyl phosphate C27 200 Irganox 1135 + 200 Irgafos 7 7 14 OPH + 1000 tristrimethylsilyl phosphate

(33) Result: 1 ppm of tristrimethylsilyl phosphate slightly improves flocculation. From 5 ppm upward of tristrimethylsilyl phosphate, the improvement is very significant. 300 and 1000 ppm of tristrimethylsilyl phosphate have negative effects again.