Process for preparing polyisocyanates which are flocculation-stable in solvents from (cyclo)aliphatic diisocyanates

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, the method comprising mixing the polyisocyanate mixture with an additive, wherein said mixing is carried out in the presence of water and a solvent, thereby reducing flocculation, precipitation, or both, of the polyisocyanate mixture, and wherein the additive is selected from the group consisting of a1) an organic acid having a pKa of below 4.2, selected from the group consisting of a1a) an aromatic sulfonic acid, and a1b) a singularly or doubly alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid having two carbon atoms, a singularly or doubly halogen-, alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid, an alkenedicarboxylic acid or an alkanedicarboxylic acid having at least three carbon atoms; a2) a phosphite: ##STR00006## and a4) an acidic phosphorus derivative selected from the group consisting of a4a) a mono- and di-C.sub.1 to C.sub.12 alkyl phosphate, a4c) a mono-C.sub.1 to C.sub.12 alkyl phosphinate, and a4d) an alkyl derivative of a phosphorus-containing diacid, and wherein: a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate, biuret, allophanate, or allophanate with urethane group, the additive does not include a 2-chloroalkanecarboxylic acid or a 3-chloro alkanecarboxylic acid; and R is optionally an aryl group which is substituted in positions 2, 4 and 6 as follows: position 2: tert-butyl, or tert-amyl, position 4: hydrogen, alkyl, tert-butyl, or tert-amyl, and position 6: hydrogen, alkyl, tert-butyl, or tert-amyl, with the proviso that at least one of substituents in positions 4 and 6 is not hydrogen.

2. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture is (cyclo)aliphatic.

3. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture is based on hexamethylene diisocyanate, isophorone diisocyanate, or both, as a monomer.

4. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate, biuret, or an allophanate group.

5. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate group, a urethane group, an allophanate group, or a mixture thereof, obtained in the presence of an ammonium carboxylate or an ammonium a-hydroxycarboxylate catalyst.

6. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate group obtained by thermal deactivation of a catalyst.

7. The method according to claim 1, wherein a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate group obtained by thermal deactivation of a catalyst through addition of a deactivator.

8. The method according to claim 1, wherein a substoichiometric amount of the additive is added in relation to an amount of the water present in the polyisocyanate mixture.

9. The method according to claim 1, wherein the additive is selected from the group consisting of di(2-ethylhexyl) phosphate, dibutyl phosphate, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, a dioctylphosphonic ester, a di(2-ethylhexyl)phosphonic ester, a di-n-butylphosphonic ester, a diethylphosphonic ester, a dimethylphosphonic ester, a 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, and dodecylbenzenesulfonic acid.

10. The method according to claim 1, wherein a total amount of the water ranges from 100 to 800 ppm relative to an amount of the solvent.

11. The method according to claim 1, wherein a total amount of the water ranges from 400 to 800 ppm relative to an amount of the solvent.

12. The method according to claim 1, wherein the solvent is at least one selected from the group consisting of an aromatic hydrocarbon, a (cyclo)aliphatic hydrocarbon, a chlorinated hydrocarbon, a ketone, an ester, an alkoxylated alkyl alkanoate, and an ether.

13. The method according to claim 1, wherein the solvent is at least one selected from the group consisting of n-butyl acetate, ethyl acetate, 1-methoxyprop-2-yl acetate, 2-methoxyethyl acetate, and an aromatic hydrocarbon.

14. The method according to claim 1, wherein the polyisocyanate mixture further comprises at least one phenyl or bridged bisphenol which has one phenolic hydroxyl group on an aromatic ring of the at least one phenyl or bridged bisphenol and has alkyl groups in positions ortho to the phenolic hydroxyl group.

15. The method according to claim 14, wherein the polyisocyanate mixture further comprises a dialkyl phosphate, a dialkyl phosphonate, an aromatic sulfonic acid, or a mixture thereof.

16. The method according to claim 14, wherein the polyisocyanate mixture further comprises a Lewis acid.

17. A method for stabilizing a polyisocyanate or a polyisocyanate mixture in a solvent against flocculation during storage, the method comprising mixing, in the presence of water and a solvent, the polyisocyanate or the polyisocyanate mixture with at least one additive selected from the group consisting of a1) an organic acid having a pKa of below 4.2, selected from the group consisting of a1a) an aromatic sulfonic acid, and a1b) a singularly or doubly alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid having two carbon atoms, a singularly or doubly halogen-, alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid, an alkenedicarboxylic acid or an alkanedicarboxylic acid having at least three carbon atoms; a2) a phosphite: ##STR00007## and a4) an acidic phosphorus derivative selected from the group consisting of a4a) a mono- and di-C.sub.1 to C.sub.12 alkyl phosphate, a4c) a mono-C.sub.1 to C.sub.12 alkyl phosphinate, and a4d) an alkyl derivative of a phosphorus-containing diacid, wherein: the polyisocyanate mixture comprises at least one selected from the group consisting of a Lewis acid as a catalyst, an antioxidant, and a coating additive; the additive does not include a 2-chloroalkanecarboxylic acid or a 3-chloro alkanecarboxylic acid; and R is optionally an aryl group which is substituted in positions 2, 4 and 6 as follows: position 2: tert-butyl, or tert-amyl, position 4: hydrogen, alkyl, tert-butyl, or tert-amyl, and position 6: hydrogen, alkyl, tert-butyl, or tert-amyl, with the proviso that at least one of substituents in positions 4 and 6 is not hydrogen.

18. The method according to claim 17, wherein the polyisocyanate mixture comprises at least one selected from the group consisting of a Lewis acid as a catalyst and an antioxidant.

19. A method for coating a substrate with a polyisocyanate or a polyisocyanate mixture stabilized against flocculation during storage in a solvent in the presence of water, the method comprising: mixing the polyisocyanate or the polyisocyanate mixture with at least one additive, thereby forming a first mixture, mixing the first mixture with a solvent and optionally with at least one other additive, thereby forming a second mixture, optionally storing the second mixture in the presence of the water, mixing the second mixture with at least one binder-comprising component, thereby forming a third mixture, and applying the third mixture to a substrate, wherein the at least one additive is selected from the group consisting of a1) an organic acid having a pKa of below 4.2, selected from the group consisting of a1a) an aromatic sulfonic acid, and a1b) a singularly or doubly alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid having two carbon atoms, a singularly or doubly halogen-, alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid, an alkenedicarboxylic acid or an alkanedicarboxylic acid having at least three carbon atoms; a2) a phosphite: ##STR00008## and a4) an acidic phosphorus derivative selected from the group consisting of a4a) a mono- and di-C.sub.1 to C.sub.12 alkyl phosphate, a4c) a mono-C.sub.1 to C.sub.12 alkyl phosphinate, and a4d) an alkyl derivative of a phosphorus-containing diacid, wherein: the additive does not include a 2-chloroalkanecarboxylic acid or a 3-chloro alkanecarboxylic acid; and R is optionally an aryl group which is substituted in positions 2, 4 and 6 as follows: position 2: tert-butyl, or tert-amyl, position 4: hydrogen, alkyl, tert-butyl, or tert-amyl, and position 6: hydrogen, alkyl, tert-butyl, or tert-amyl, with the proviso that at least one of substituents in positions 4 and 6 is not hydrogen.

20. The method according to claim 19, wherein the binder-comprising component comprises a compound selected from the group consisting of a polyacrylate polyol, a polyester polyol, a polyurethane polyol, a polycarbonate polyol, and a polyether polyol.

21. The method according to claim 19, wherein the substrate is a compound in a primer, a filler, a pigmented topcoat, a basecoat and a clearcoat in an automotive refinishing or large-vehicle finishing sector and for a utility vehicle in an agricultural or construction sector.

Description

EXAMPLES

Ingredients

(1) Polyisocyanates

(2) PI-1-PI-3, PI-5: Various batches of isocyanurate Basonat HI 100 with a viscosity of about 2800 mPa*s (BASF SE)

(3) PI-4: Biuret Basonat HB 100 (BASF SE)

(4) PI-6: Isocyanurate of isophorone diisocyanate, 70% in Solvesso 100, Basonat IT 270 S (BASF SE)

(5) PI-7: Allophanate of hexamethylene diisocyanate, Basonat HA 100, viscosity about 1200 mPa*s (BASF SE)

(6) PI-8: Allophanate of hexamethylene diisocyanate, Basonat HA 300, viscosity about 300 mPa*s (BASF SE)

(7) Additives. The compounds used in the tables below are abbreviated as follows:

(8) Sterically Hindered Phenols (Comparative): BHT=2,6-Di-tert-butyl-4-methylphenol 1135=Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C8 branched alkyl ester, Irganox 1135 (BASF SE)

(9) Standard Water Scavengers (Comparative): TI=para-Toluenesulfonyl isocyanate, additive TI (Borchers) OF=Triethyl orthoformate, additive OF (Borchers)

(10) Monocyclic Phosphites (Comparative): Tppt=Triphenyl phosphite 168=Tris(2,4-di-tert-butylphenyl)phosphate, Irgafos 168 (BASF)

(11) Acids (Comparative): Ac=Acetic acid MS=Methanesulfonic acid TFAc=Trifluoroacetic acid

(12) Other Compounds (Comparative): DPP=Diphenyl phosphonate

(13) Polycyclic Phosphites (Inventive): 126=Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite=Irgafos 126 (BASF SE) 9228=3,9-Bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane=pentaerythritol diphosphite=Doverphos S-9228 (Dover Chemical Corporation) 618=Weston 618=Doverphos S 680 (CAS 3806-34-6) 3,9-Bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (CAS 80693-00-1)=ADK Stab PEP-3

(14) Phosphonite (Inventive): EPQ=Phosphorus trichloride, reaction products with 1,1-biphenyl- and 2,4-bis(1,1-dimethylethyl)-phenol=Irgafos P-EPQ (BASF SE)

(15) Acids 2-CPS=2-Chloropropionic acid 3-CPS=3-Chloropropionic acid DEHP=Diethylhexyl phosphate OPH=Irgafos OPH=dioctyl phosphonate (BASF SE) DOPO=Sanko HCA (CAS 35948-25-5)=9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxides (Sanko Co., Osaka, Japan) 5076=Dodecylbenzenesulfonic acid, Nacure 5076 (King Industries) T-Ac=Mercaptoacetic acid M-Ac=Methoxyacetic acid

(16) blocked sulfonic acid derivatives 5414=Nacure 5414: polymer-blocked dodecylbenzenesulfonic acid (King Industries, Inc.); ppm amounts based on solids fraction 1419=Nacure 1419=blocked dinonylnaphthalenesulfonic acid, 30% in xylene/methyl isobutyl ketone) (King Industries, Inc.); ppm amounts based on solids fraction 194=Nacure XC-194=latently blocked alkylarylsulfonic acid, 20% in solvent mixture of hydrocarbons (King Industries, Inc.); ppm amounts based on solids fraction

(17) Water was added to the solvents in order to produce more rapid flocculation than with the amounts of water present in commercial solvents. The total amounts were 400-800 ppm of total water based on solvents. The higher the water concentration, the quicker, normally, the flocculation. With relatively small amounts of water that are customary in practice, flocculation takes place after longer time periods. The water content in the experiments below is based on the solvents. It was determined by Karl-Fischer titration.

(18) Flocculation measurement: for determining the flocculation, typically 30% or 40% strength solutions of polyisocyanate in solvents or solvent mixtures were prepared. Additives were introduced via the solvents. 50 g of the mixture in 50 ml screw-top lid vessels without writing on the side were blanketed with nitrogen and stored firmly sealed at 23 C. (50% atmospheric humidity). The vessels were inspected typically daily in the first two weeks, excluding the weekends, and thereafter weekly, and at two-week intervals from 10 weeks onwards, against a dark background.

(19) Flocculation Scoring: 0 last day of measurement before flocculation, or no flocculation throughout the experiment; 1a the first day of measurement with very slight hazing or fine sediment barely visible to the naked eye 1b the last day of measurement with very slight hazing or fine sediment barely visible to the naked eye 2 the first day of measurement with clearly perceptible sediment or flocking 3 initial gelling X no further measurement

(20) The examples which follow are intended to illustrate the invention, but not to confine it to these examples.

(21) The experimental series show that in the inventive examples, longer storage times without flocculation or with lower flocculation are obtained than with the reference examples without additives and with noninventive additives.

(22) It is shown by way of example, moreover, that this effect is obtained in different typical coatings solvents such as n-butyl acetate (BuAc), xylene/butyl acetate=3:1, xylene, methoxypropyl acetate MPA, Solvesso 100, albeit to different extents.

(23) Moreover, the effect has been shown by way of example in concentrations of 30% and 40% polyisocyanate in solvents, which is typical for coatings, but already corresponds to relatively severe dilution.

Experimental Series 1

Storage of PI-1 Isocyanurate 40% in N-Butyl Acetate with a Water Content of about 800 ppm and Different Additives with Flocculation/Precipitation in Days Over 126 Days

(24) TABLE-US-00002 Flocculation Comp. Comp. Comp. Comp. Comp. Inv. Inv. Inv. Inv. Inv. Additive none Tppt 1135 TI TI 126 9228 EPQ OPH 1135 EPQ Amount 0 600 600 600 2000 600 600 200 600 200 600 (ppm) 0 (d) 13 2 13 13 14 14 126 98 42 42 1a (d) 14 7 14 14 21 21 X 112 56 56 1b (d) 14 7 14 21 21 21 X 126 70 126 2 (d) 21 7 21 21 28 28 X X 84 X

Experimental Series 2

Storage of PI-1 Isocyanurate 40% Strength in Xylene/N-Butyl Acetate=3:1 with a Water Content of 800 ppm and Different Additives Over 126 Days

(25) TABLE-US-00003 Flocculation Comp. Comp. Inv. Inv. Inv. Inv. Additive none Tppt 9228 EPQ 1135 EPQ 1135 OPH Amount 0 600 600 600 200 600 200 600 (ppm) 0 (d) 9 3 11 28 126 98 1a (d) 10 8 14 42 X 112 1b (d) 14 8 126 126 X 126 2 (d) 21 8 X X X X

Experimental Series 3

Storage of PI-1 Isocyanurate 40% in Xylene with a Water Content of 400 ppm (Saturated Solution) and Different Additives Over 210 Days

(26) TABLE-US-00004 Comp. Comp. Inv. Inv. Inv. Inv. Inv. Additive None Tppt 9228 EPQ 126 1135 EPQ 1135 OPH Amount 0 600 600 600 600 200 600 200 600 (ppm) 0 (d) 42 0 98 98 210 210 210 1a (d) 56 5 112 112 X X X 1b (d) 98 5 112 140 X X X 2 (d) 112 5 112 X X X X

Experimental Series 4

Storage of PI-1 Isocyanurate 40% in Solvesso 100 with a Water Content of 400 ppm (Saturated Solution) and Different Additives Over 126 Days

(27) TABLE-US-00005 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Inv. Inv. Inv. Inv. Additive None Tppt 168 TI TI OF OF 618 EPQ 126 OPH Amount 0 600 600 600 2000 600 2000 600 200 600 600 (ppm) 0 (d) 14 0 14 84 84 84 84 126 126 126 126 1a (d) 21 5 21 98 98 98 98 X X X X 1b (d) 126 5 28 98 98 98 98 X X X X 2 (d) X 5 42 98 98 98 98 X X X X

Experimental Series 5

Storage of PI-2 Isocyanurate 40% In Butyl Acetate with a Water Content of 800 ppm and Different Additives Over 210 Days

(28) TABLE-US-00006 Comp. Inv. Inv. Inv. Inv. Additive None DOPO 126 OPH 5414 Amount 0 200 200 200 200 (ppm) 0 (d) 5 6 7 5 210 1a (d) 6 7* 12* 6* X 1b (d) 12 210* 210* 210* X 2 (d) 13 X X X X *The sample showed a very slight hazing, which was no longer apparent after a storage time of around 12 weeks. It is assumed that these values lie in the marginal region of visual perception. No technical aids were employed.

Experimental Series 6

Storage of PI-3 Isocyanurate 30% in Butyl Acetate/Xylene=1:3 with a Water Content of 800 ppm and Different Additives Over 210 Days

(29) TABLE-US-00007 Comp. Comp. Comp. Comp. Comp. Inv. Inv. Inv. Inv. Additive None DPP Ac MS TFAc 2-CPS 3-CPS 3-CPS DEHP Amount 0 300 300 300 300 300 50 300 300 (ppm) 0 (d) 14 0 7 1 14 42 210 210 210 1a (d) 21 1 8 2 21 56 X X X 1b (d) 21 2 8 8 21 98 X X X 2 (d) 21 3 9 9 21 112 X X X Inv. Inv. Inv. Inv. Inv. Inv. Inv. Inv. Inv. Additive OPH T-Ac 5076 5414 5414 1419 1419 194 194 Amount 300 300 300 50 300 50 300 50 300 (ppm) 0 (d) 210 210 210 210 210 28 98 210 210 1a (d) X X X X X 42 112 X X 1b (d) X X X X X 182 210 X X 2 (d) X X X X X 196 X X X

Experimental Series 7

Storage of PI-3 Isocyanurate 30% in Butyl Acetate with a Water Content of 800 ppm and Different Additives Over 210 Days

(30) TABLE-US-00008 Comp. Comp. Comp. Comp. Inv. Inv. Inv. Inv. Inv. Additive none DPP Ac MS 2-CPS 2-CPS 3-CPS 3-CPS DEHP Amount 0 300 300 300 50 300 50 300 300 (ppm) 0 (d) 8 1 11 1 28 42 28 28 14 1a (d) X 4 12 4 X 56 X X X 1b (d) X 4 12 4 X 70 X X X 2 (d) X 4 13 4 X 182 X X X 3 (d) 11 X X X 42 X 42 42 21 Inv. Inv. Inv. Inv. Inv. Inv. Inv. Inv. Inv. Additive OPH T-Ac 5076 5414 5414 194 194 1419 1419 Amount 300 300 300 50 300 50 300 50 300 (ppm) 0 (d) 210 21 98 28 210 210 112 21 126 1a (d) X 28 X X X X 126 28 X 1b (d) X 28 X X X X 210 28 X 2 (d) X 28 X X X X X 28 X 3 (d) X X 112 42 X X X X 140

Experimental Series 8

Storage of PI-4 Biuret 30% in Butyl Acetate with a Water Content of 800 ppm and Different Additives Over 210 Days

(31) TABLE-US-00009 Comp. Inv. Inv. Additive None OPH 126 Amount 0 300 300 (ppm) 0 (d) 8 112 98 1a (d) 11 126 X 1b (d) 12 182 X 2 (d) 13 196 X 3 (d) X X 182

Experimental Series 9

Storage of PI-5 Isocyanurate, 30% in Xylene/Butyl Acetate=3:1 with a Water Content of 600 ppm and Different Additives Over 210 Days

(32) TABLE-US-00010 Comp. Inv. Inv. Inv. Inv. Inv. Inv. Inv. Additive none DEHP DEHP DEHP DEHP DEHP DEHP 5076 Amount 0 20 40 100 40 40 40 10 (ppm) Additive BHT BHT Amount 100 100 (ppm) Additive OPH OPH Amount 300 300 (ppm) 0 (d) 13 154 210 154 210 28 154 210 1a (d) 14 168 X 168 X 42 168 X 1b (d) 14 210 X 210 X 210 210 X 2 (d) 21 X X X X X X X 3 (d) X X X X X X X X Inv. Inv. Inv. Additive 5076 5076 5076 Amount 20 50 20 (ppm) Additive BHT Amount 100 (ppm) 0 (d) 112 210 210 1a (d) 126 X X 1b (d) 210 X X 2 (d) X X X 3 (d) X X X

Experimental Series 10

Storage of

(33) a) PI-5 Basonat HI 100/PI-6 Basonat IT 270 S=70:30 solids/solids

(34) b) PI-7 Basonat HA 100

(35) c) PI-8 Basonat HA 300

(36) 30% (total solids) in Solvesso 100 with a water content of 100 ppm and additive

(37) TABLE-US-00011 Comp. Inv. Comp. Inv. Polyisocyanate PI-7 PI-7 PI-8 PI-8 Additive none DEHP none DEHP Amount 0 50 0 50 (ppm) 0 (d) 56 210 140 210 1a (d) 70 X 154 X 1b (d) 140 X 210 X 2 (d) 154 X X X 3 (d) X X X X

Experimental Series 11

Like Experimental Series 10, but in Butyl Acetate with a Water Content of 400 ppm and Additive

(38) TABLE-US-00012 Comp. Inv. Comp. Inv. Polyisocyanate PI-5/PI-6 PI-5/PI-6 PI-8 PI-8 Additive none DEHP none DEHP Amount 0 50 0 50 (ppm) 0 (d) 56 182 126 168 1a (d) 70 196 140 182 1b (d) 70 210 210 210 2 (d) 84 X X X 3 (d) X X X X

Experimental Series 12

Like Experimental Series 10, but Xylene/Butyl Acetate Equals 3:1 with a Water Content of about 200 ppm and Additive

(39) TABLE-US-00013 Polyisocyanate Comp. Inv. Comp. Inv. Comp. Inv. PI-5/PI-6 PI-5/PI-6 PI-7 PI-7 PI-8 PI-8 Additive none DEHP none DEHP none DEHP Amount 0 50 0 50 0 50 (ppm) 0 (d) 56 182 42 182 70 210 1a (d) 70 196 56 196 84 X 1b (d) 70 210 70 210 210 X 2 (d) 70 X 84 X X X 3 (d) X X X X X X