AQUEOUS POLYCARBODIIMIDE DISPERSION WITH IMPROVED STORAGE STABILITY, AND METHOD FOR PRODUCING SAME

Abstract

The invention relates to storage-stable aqueous dispersions of hydrophilically modified polycarbodiimide resins, a method for producing same, and the use of a salt component to reduce carbodiimide hydrolysis in aqueous polycarbodiimide dispersions.

Claims

1. An aqueous dispersion of hydrophilically modified polycarbodiimide resins, comprising: a salt component that comprises at least one salt having a cation and an anion that is present in its highest deprotonation level and having a pK.sub.B of 9, wherein the dispersion has an electrical conductivity in accordance with DIN EN 27888 and measured at 20 C. that is higher than that of a dispersion minus the salt component but otherwise identical, wherein, when the salt component comprises magnesium sulfate and/or calcium sulfate, at least one further anion having a pK.sub.B of 9 is present in its highest deprotonation level in the salt component, and wherein, when the salt component comprises aluminum(III) chloride in a content of 95 mol %, the electrical conductivity of the dispersion in accordance with DIN EN 27888 and measured at 20 C. is 1000% of the electrical conductivity of a dispersion minus the salt component but otherwise identical.

2. The dispersion as claimed in claim 1, wherein the dispersion has an electrical conductivity in accordance with DIN EN 27888 and measured at 20 C. that is 140% of the electrical conductivity of a dispersion minus the salt component but otherwise identical.

3. The dispersion as claimed in claim 1, wherein the dispersion has an electrical conductivity in accordance with DIN EN 27888 and measured at 20 C. of 300 S/cm.

4. The dispersion as claimed in claim 1, wherein the salt component comprises a halide anion.

5. The dispersion as claimed in claim 1, wherein the salt component comprises an alkali metal cation or an alkaline earth metal cation.

6. The dispersion as claimed in claim 1, wherein the dispersion was additionally at least partially freed of CO.sub.2 by application of vacuum.

7. The dispersion as claimed in claim 1, wherein the dispersion has a pH of 5 to 9.8.

8. The dispersion as claimed in claim 1, wherein the salt component is present in an amount by weight of 0.01% to 1% based on the total weight of the dispersion.

9. The dispersion as claimed in claim 1, wherein the dispersion contains 90% of an original polycarbodiimide content after storage at 60 C. for 120 hours.

10. A method for preparing an aqueous dispersion of hydrophilically modified polycarbodiimide resins, comprising: A) reacting a polyisocyanate in the presence of a carbodiimidization catalyst to obtain a polycarbodiimide; B) adding a compound that contains at least one group reactive toward isocyanate and/or carbodiimide groups during or after polycarbodiimide formation to form a hydrophilized polycarbodiimide; C) dispersing the hydrophilized polycarbodiimide in water to obtain a dispersion; and D) adding a salt component to at least one of: the water used to obtain the dispersion, the dispersion, the polyisocyanate, or the compound wherein the dispersion has an electrical conductivity in accordance with DIN EN 27888 and measured at 20 C. that is higher than that of a dispersion minus the salt component but otherwise identical, wherein the salt component comprises at least one salt having a cation and an anion that is present in its highest deprotonation level and having a pK.sub.B of 9, wherein, when the salt component comprises magnesium sulfate and/or calcium sulfate, at least one further anion having a pK.sub.B of 9 is present in its highest deprotonation level in the salt component, and wherein, when the salt component comprises aluminum(III) chloride in a content of 95 mol %, the electrical conductivity of the dispersion in accordance with DIN EN 27888 and measured at 20 C. is 1000% of the electrical conductivity of a dispersion minus the salt component but otherwise identical.

11. The method as claimed in claim 10, wherein the compound comprises a hydrophilic group and at least one group reactive toward isocyanate and/or carbodiimide groups.

12. The method as claimed in claim 10, wherein the salt component comprises a halide anion and/or an alkali metal cation or alkaline earth metal cation.

13. The method as claimed in claim 10, wherein the dispersion was additionally at least partially freed of CO.sub.2 by application of vacuum.

14. The method as claimed in claim 10, wherein the polyisocyanate is an aliphatic polyisocyanate.

15. A method of reducing carbodiimide hydrolysis in aqueous dispersions of hydrophilically modified polycarbodiimide resins, comprising: adding a salt component to a hydrophilically modified polycarbodiimide resin, wherein the salt component comprises at least one salt having a cation and an anion that in its highest deprotonation level and having a pK.sub.B of 9, wherein, when the salt component comprises at least one of aluminum(III) chloride, magnesium sulfate, or calcium sulfate, at least one further anion is present in the salt component in its highest deprotonation level and having a pK.sub.B of 9.

Description

EXAMPLES

[0073] The present invention is elucidated further by the examples that follow, without being restricted thereto.

[0074] Starting Materials: [0075] Cycloaliphatic polyisocyanate H12MDI: 4,4-Diisocyanatodicyclohexylmethane, CAS No. 79103-62-1 (Desmodur W, Covestro Deutschland AG, Leverkusen, Germany) [0076] Carbodiimidization catalyst 1,1-MPO: technical mixture of 1-methyl-2-phospholene-1-oxide and 1-methyl-3-phospholene-1-oxide, CAS No. 872-45-7 and 930-38-1 (Clariant AG, Muttenz, Switzerland) [0077] Monomethoxypolyethylenglycol 750, MPEG 750: CAS No. 9004-74-4: (Aldrich, Germany) [0078] Butoxyethanol: CAS No. 111-76-2: (SysKem Chemie GmbH, Wuppertal, Germany)

[0079] Methods: [0080] Determination of average particle size: The particle size of the polycarbodiimide droplets in the dispersions/solutions are determined by laser correlation spectroscopy (instrument: Malvern Zetasizer 1000, Malvern Inst. Limited). [0081] Conductivity: The electrical conductivity [S/cm] is determined using a SevenCompact S230 conductivity meter from Mettler Toledo in combination with an InLab 710 measurement probe. This was done in accordance with standard DIN EN 27888. [0082] Determination of the nonvolatiles fraction: The nonvolatiles fraction in the dispersions polycarbodiimide is determined in accordance with DIN EN ISO 3251, with the conditions in the investigations being defined by the following parameters: 0.5 g/120 min/125 C. [0083] Stability testing: The polycarbodiimide dispersions were stored in closed PE bottles at 60 C. for a period of 120 hours. The carbodiimide concentration, electrical conductivity, and pH of the samples were determined before and after hot storage. [0084] Determination of the carbodiimide concentration: The carbodiimide concentration is determined by ATR infrared spectroscopy on a Perkin Elmer Spectrum Two. [0085] Firstly, solutions of dicyclohexylcarbodiimide (DCC) in ethanol were prepared (concentrations: 0.1 mmol/g, 0.2 mmol/g, 0.5 mmol/g, 1.0 mmol/g, 1.5 mmol/g, and 2 mmol/g). The IR spectra of these solutions were recorded. The peak areas (P.sub.A) of the carbodiimide band at approx. 2118 cm.sup.1 were determined. The data (concentration c of the DCC solutions and measured P.sub.A values) were used to generate a calibration line:

P.sub.A=m.Math.c[meq DCC/g],

where m is the slope of the calibration lines. [0086] The carbodiimide concentration is determined from P.sub.A of the band at approx. 2118 cm.sup.1. The concentration [meq DCC/g] is calculated from P.sub.A/m. [0087] The change in the carbodiimide concentration is reported as a percentage of the baseline value. Based on the measurement conditions, the reported values for the change in the carbodiimide concentration is assumed to be accurate to 5 percentage points.

[0088] Unless otherwise stated, all analytical determinations refer to a temperature of 23 C. The reference temperature of the meter for the electrical conductivity was 20 C.

[0089] Preparation of the Polycarbodiimide Dispersions

[0090] Polycarbodiimide dispersions pCDI 1 to pCDI 6 were prepared in accordance with example 2 from WO 2011/120928 A2 (=EP 2552982 A2). This afforded an almost transparent dispersion having a pH of between 7 and 9.7, an average particle size of 35 nm, and a nonvolatiles fraction (solids content) of approx. 40% by weight. Dispersion pCDI 5 was freed of dissolved CO.sub.2 by application of vacuum.

[0091] Stabilization of the polycarbodiimide dispersion: 0.01% to 1.0% by weight of salt was added to the polycarbodiimide dispersion to adjust the conductivity to a value >250 S/cm.

[0092] The results obtained are shown in the tables below. Examples marked with (*) are comparative examples.

Example 1: pCDI 1

[0093]

TABLE-US-00001 Before hot storage % of After hot storage S/cm 120 h/60 C. Decrease Salt without meq meq meq DCC/g Salt [wt.-%] pH S/cm salt DCC/g pH S/cm DCC/g [%] without 0 9.7 227 100% 1.05 10.4 271 0.64 39.0 (*) NaCl 0.05 9.8 831 366% 1.05 10.2 765 0.83 21.0 NaCl 0.10 9.8 1491 657% 1.02 10.1 1399 0.91 10.8 NaCl 0.20 9.8 2531 1115% 1.06 10.1 1410 0.91 14.2 NaCl 0.50 9.8 5664 2495% 1.03 10.2 5737 1.01 1.9 LiCl 0.05 9.8 360 159% 1.02 9.8 823 0.93 8.8 LiCl 0.10 9.8 981 432% 1.02 9.8 1243 0.95 6.9 LiCl 0.20 9.7 790 348% 1.04 9.7 2881 1.02 1.9 LiCl 0.50 9.5 1267 558% 1.04 9.5 6674 1.05 1.0 MgCl.sub.26H 0.05 9.6 500 220% 1.07 10.1 284 0.90 15.9 .sub.2O MgCl.sub.26H 0.10 9.5 700 308% 1.10 10.0 463 0.94 14.5 .sub.2O MgCl.sub.26H 0.20 9.4 1261 556% 1.05 9.5 1014 0.94 10.5 .sub.2O MgCl.sub.26H 0.50 9.3 2910 1282% 1.04 9.3 2641 0.96 7.7 .sub.2O AlCl.sub.3 0.05 6.6 373 164% 1.09 9.1 273 0.89 18.3 AlCl.sub.3 0.10 3.8 577 254% 1.07 8.2 372 0.97 9.3 AlCl.sub.3 0.20 3.2 961 423% 1.04 5.6 515 0.81 22.1 AlCl.sub.3 (*) 0.50 3.3 4844 2134% 1.01 3.2 3540 0.42 58.4 NaI 0.05 9.5 316 139% 1.02 9.8 453 0.71 30.4 NaI 0.10 9.5 327 144% 1.02 9.9 562 0.95 6.9 NaI 0.20 9.7 591 260% 0.98 10.1 822 0.99 1.0

Example 2: pCDI 2

[0094]

TABLE-US-00002 Before hot storage % of After hot storage S/cm 120 h/60 C. Salt without meq meq Decrease meq Salt [wt.-%] pH S/cm salt DCC/g pH S/cm DCC/g DCC/g [%] without (*) 0 8.8 115 100% 1.27 9.6 163 0.78 38.6 NaCl 0.05 9.0 721 627% 1.27 9.6 718 1.14 10.2 NaCl 0.10 9.1 1333 1159% 1.27 9.6 1365 1.18 7.1 NaCl 0.20 8.9 2299 1999% 1.30 9.5 2324 1.21 6.9 NaCl 0.50 9.2 5388 4685% 1.27 9.5 5478 1.21 4.7 LiCl 0.05 9.1 546 475% 1.28 9.8 761 1.19 7.0 LiCl 0.10 9.1 774 673% 1.27 9.6 1473 1.22 3.9 LiCl 0.20 9.1 1212 1054% 1.27 9.6 2769 1.14 10.2 LiCl 0.50 9.2 5059 4399% 1.26 9.5 6352 1.26 0.0 MgCl.sub.26H.sub.2O 0.05 8.9 424 369% 1.27 9.4 404 1.13 11.0 MgCl.sub.26H.sub.2O 0.10 8.9 676 588% 1.28 9.4 652 1.15 10.2 MgCl.sub.26H.sub.2O 0.20 8.9 1247 1084% 1.27 9.3 1240 1.26 0.8 MgCl.sub.26H.sub.2O 0.50 8.9 2814 2447% 1.29 9.1 2879 1.24 3.9 AlCl.sub.3 0.05 4.4 387 337% 1.26 7.1 1336 1.10 12.7 AlCl.sub.3 (*) 0.10 3.7 1002 871% 1.16 4.2 727 0.60 48.3 AlCl.sub.3 (*) 0.20 3.5 1841 1601% 1.11 3.3 534 0.44 60.4 AlCl.sub.3 (*) 0.50 3.1 4088 3555% 1.11 3.1 448 0.37 66.7 NaI 0.05 9.2 228 198% 1.15 9.5 269 1.24 7.8 NaI 0.10 9.4 366 318% 1.22 9.5 415 1.26 3.3 NaI 0.20 9.6 703 611% 1.26 9.9 781 1.25 0.8

Example 3: pCDI 3

[0095]

TABLE-US-00003 Before hot storage % of Salt S/cm After hot storage Decrease [wt.- without meq 120 h/60 C. meq DCC/g Salt %] pH S/cm salt DCC/g pH S/cm meq DCC/g [%] without (*) 0 8.1 205 100% 1.00 solidified 0.63 37.0 LiCl 0.05 8.4 468 228% 0.99 10.0 743 0.93 6.1 LiCl 0.10 8.3 731 357% 1.01 10.3 1454 1.00 1.0 LiCl 0.20 8.3 1734 846% 1.01 10.1 2747 1.05 4.0 LiCl 0.50 8.1 1049 512% 1.02 10.0 6641 1.03 1.0 KCl 0.10 8.4 1244 607% 1.01 10.2 1107 0.90 10.9 KCl 0.20 8.4 2270 1107% 1.00 9.6 2084 0.94 6.0 KBr 0.10 8.5 789 385% 1.01 9.9 674 0.91 9.9 KBr 0.20 8.5 1415 690% 1.01 9.8 1275 0.98 3.0 MgSO.sub.4 (*) 0.10 8.1 685 334% 1.00 8.5 651 0.62 38.0 MgSO.sub.4 (*) 0.20 8.1 1080 527% 0.97 8.7 1007 0.62 36.1 CaSO.sub.4 (*) 0.10 7.8 562 274% 0.97 7.5 558 0.64 34.0 CaSO.sub.4 (*) 0.20 7.9 506 247% 0.99 7.9 601 0.66 33.3 NaI 0.05 8.6 271 132% 1.01 8.8 348 0.73 27.7 NaI 0.10 8.7 334 163% 0.96 9.2 445 0.95 1.0 NaI 0.20 8.7 698 340% 0.95 9.4 713 0.99 4.2

Example 4: pCDI 4

[0096]

TABLE-US-00004 Before hot storage % of After hot storage De- S/cm 120 h/60 C. crease Salt with- meq meq meq [wt.- S/ out DCC/ S/ DCC/ DCC/g Salt %] pH cm salt g pH cm g [%] with- 0 8.9 157 100% 1.15 solidified 0.67 41.7 out (*) LiCl 0.05 9.0 678 432% 1.14 10.1 748 1.07 6.1 LiCl 0.10 8.8 718 457% 1.13 10.2 1426 1.13 0.0 LiCl 0.20 8.8 1309 834% 1.14 9.6 2693 1.10 3.5 LiCl 0.50 8.8 3733 2378% 1.15 9.5 6418 1.17 1.7 KCl 0.10 9.1 1195 761% 1.16 10.0 1110 1.07 7.8 KCl 0.20 9.2 2221 1415% 1.14 9.7 2081 1.05 7.9 KBr 0.10 9.3 719 458% 1.15 9.8 668 1.07 7.0 KBr 0.20 9.4 1362 868% 1.15 9.9 1300 1.07 7.0 NaI 0.05 9.0 216 138% 1.09 9.4 305 0.99 9.2 NaI 0.10 9.1 370 236% 1.15 9.5 414 1.07 7.0 NaI 0.20 9.2 706 450% 1.09 9.8 718 1.12 2.8

Example 5: pCDI 5

[0097]

TABLE-US-00005 Before hot storage De- % of After hot storage crease Salt S/cm meq 120 h/60 C. meq [wt.- S/ without DCC/ S/ meq DCC/g Salt %] pH cm salt g pH cm DCC/g [%] with- 0 7.1 174 100% 1.43 7.7 174 1.18 17.5 out (*) NaCl 0.10 7.5 1269 729% 1.41 7.9 1262 1.35 4.3 NaCl 0.20 7.4 2325 1336% 1.42 7.8 2460 1.36 4.2 NaCl 0.50 7.4 5638 3240% 1.38 7.9 5704 1.39 0.7

Example 6: pCDI 7 (pH of Dispersion without Addition of Salt and Before Hot Storage: 9.4

[0098]

TABLE-US-00006 Before hot storage % of After hot storage Salt S/cm 120 h/60 C. Decrease [mmol/100 g without meq meq meq DCC/g Salt dispersion] pH S/cm salt DCC/g pH S/cm DCC/g [%] without 0 9.4 123 100% 1.28 9.5 160 0.97 24.2 (*) NaCl 2.5 9.5 1764 1434% 1.25 9.5 1697 1.24 0.8 NaCl 5.0 9.4 3350 2724% 1.25 9.4 3230 1.29 3.2 KCl 2.5 9.4 2078 1689% 1.27 9.5 1993 1.24 2.4 KCl 5.0 9.3 3943 3206% 1.25 9.5 3846 1.24 0.8 KBr 2.5 9.4 1566 1273% 1.28 9.5 1523 1.25 2.3 KBr 5.0 9.3 2912 2367% 1.24 9.4 2871 1.25 0.8 LiCl 2.5 9.6 1995 1622% 1.26 9.7 1937 1.27 0.8 LiCl 5.0 9.5 3818 3104% 1.26 9.6 3725 1.27 0.8 KF 2.5 9.3 1863 1515% 1.26 9.5 1877 1.09 13.5 KF 5.0 9.3 3402 2766% 1.27 9.5 3357 1.10 13.4 NaI 2.5 9.8 1506 1224% 1.28 10.1 1450 1.26 1.6 NaI 5.0 9.9 2871 2334% 1.26 10.2 2783 1.27 0.8