POLYMERIC CARBODIIMIDES, PROCESSES FOR THE PREPARATION AND USE THEREOF

Abstract

The invention relates to novel polycarbodiimides which are capable of easy and reliable production, have high average molar masses and effect excellent hydrolysis stabilization, to processes for the production thereof and to the use thereof.

Claims

1. A polycarbodiimide of formula (I) ##STR00004## in which the radicals R may be identical or different and are selected from NCNR.sup.I, wherein the radicals R.sup.I represent C.sub.1-C.sub.22-alkyl, unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.6-C.sub.12-cycloalkyl, unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.6-C.sub.13-aryl or unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.5-C.sub.18-aralkyl and R.sup.1, R.sup.2 and R.sup.3 in each case identically or independently of one another represent methyl, ethyl, i-propyl- or n-propyl, n-butyl or i-butyl or t-butyl and n is from 20 to 500, wherein the average molar mass Mw is more than 10000 and the proportion of polycarbodiimide having a molar mass of 30,000 g/mol or more is less than 20% by weight.

2. The polycarbodiimide according to claim 1, wherein the average molar mass is from 10,000 g/mol to 20,000 g/mol.

3. The polycarbodiimide according to claim 1, wherein the proportion of polycarbodiimid having a molar mass of 30,000 g/mol or more is less than 15% by weight.

4. The polycarbodiimide according to claim 1, wherein R.sup.I represents C.sub.1-C.sub.12-alkyl-substituted C.sub.6-C.sub.12-aryls.

5. The polycarbodiimide according to claim 1, wherein R.sup.1, R.sup.2 and R.sup.3 represent i-propyl and R.sup.I represents diisopropylphenyl and/or triisopropylphenyl.

6. The polycarbodiimide according to claim 1, wherein the mass ratio of the radicals R to the radical of the compound of formula (I) is in the range from 1:100 to 1:20.

7. The polycarbodiimide according to claim 1, wherein the carbodiimide content is 14-17% by weight.

8. A process for producing polycarbodiimides of formula (I) ##STR00005## by reaction of diisocyanates of formula (II) ##STR00006## and monoisocyanates of formula R.sup.INCO, wherein the radicals R may be identical or different and are selected from NCNR.sup.I, wherein the radicals R.sup.I represent C.sub.1-C.sub.22-alkyl, unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.6-C.sub.12-cycloalkyl, unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.6-C.sub.12-aryl or unsubstituted or C.sub.1-C.sub.12-alkyl-substituted C.sub.1-C.sub.18-aralkyl and R.sup.1, R.sup.2 and R.sup.3 in each case identically or independently of one another represent methyl, ethyl, i-propyl- or n-propyl, n-butyl or i-butyl or t-butyl and n is from 20 to 500, at temperatures of 80 C. to 200 C. in the presence of catalysts and optionally solvent to eliminate carbon dioxide, wherein the mass ratio of diisocyanates to monoisocyanates is from 20:1 to 100:1.

9. The process according to claim 8, wherein the diisocyanates of formula (II) are first mixed with the monoisocyanates of formula R.sup.INCO and then heated to the reaction temperature and reacted as a mixture.

10. The process according to claim 8, wherein first the diisocyanates of formula (II) are partially carbodiimidized in the presence of catalysts and optionally solvent and then the monoisocyanates of formula RINCO are added to the reaction mixture to complete the carbodiimidization.

11. The process according to claim 8, wherein after reaction the mixture is stirred at elevated temperature under reduced pressure, the residual content of isocyanates is reduced to <0.1% by weight.

12. The process according to claim 8, wherein the polycarbodiimides obtained during the reaction are pelletized on a cooling belt or are finished into flakes on a flake roller.

13. The process according to claim 8, wherein the reaction is carried out at a temperature of 160 C. to 180 C.

14. (canceled)

15. (canceled)

16. A method of stabilizing an ester-based polymer comprising incorporating the polycarbodiimide according to claim 1 into the ester-based polymer.

17. The method according to claim 16, wherein the ester-based polymer is selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), copolyesters, thermoplastic polyester elastomers (TPE E), ethylene vinyl acetate (EVA), polylactic acid (PLA) and/or PLA derivatives, polybutylene adipate-terephthalates (PBAT), polybutylene succinates 30 (PBS), polyhydroxyalkanoates (PHA) and blends thereof, and polyurethane elastomers.

18. The method according to claim 16, wherein R.sup.1, R.sup.2 and R.sup.3 represent i-propyl, R.sup.I represents diisopropylphenyl and/or triisopropylphenyl, and the ester-based polymer is polyethylene terephthalate (PBT).

19. A homogeneous composition comprising an ester-based polymer and the carbodiimide according to claim 1.

20. The composition according to claim 19, wherein R.sup.1, R.sup.2 and R.sup.3 represent i-propyl and R.sup.I represents diisopropylphenyl and/or triisopropylphenyl.

21. The composition according to claim 20, wherein the ester-based polymer is selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), copolyesters, thermoplastic polyester elastomers (TPE E), ethylene vinyl acetate (EVA), polylactic acid (PLA) and/or PLA derivatives, polybutylene adipate-terephthalates (PBAT), polybutylene succinates 30 (PBS), polyhydroxyalkanoates (PHA) and blends thereof, and polyurethane elastomers.

22. The composition according to claim 21, wherein the ester-based polymer is polyethylene terephthalate (PBT), DMF/polyurethane dispersion, or rollable polyurethane elastomer.

Description

EXAMPLES

Determination of Molar Mass:

[0032] Apparatus Instrument Ultimate 3000 [0033] Detector RI ERC-7515A [0034] Combination of 3 columns (PSS SDV 5 100A, PSS SDV 5 500A and PSS SDV 5 10000A, Material PL-Gel 10e4 A, length 300 mm, diameter 8 mm) [0035] PSS WinGPC-Unichrom software [0036] Volumetric bottle 25 ml [0037] Pipetman 100 l (0.0001 g) [0038] Reagents Standard samples [0039] Polystyrene standard (polydispersity index less than 1.2) [0040] Solvents 2,6-di-tert-butyl-1,4-methylphenol (BHT) [0041] Tetrahydrofuran (THF) [0042] Toluene [0043] Parameter V (Injection 100 l quantities) [0044] Flow 1.0 ml/min [0045] Eluent THF [0046] Pressure 36 bar [0047] Temperature 40 C.

Carbodiimidization

[0048] Pure 1,3,5-triisopropylphenyl diisocyanate (TRIDI) for CDI 1 or a mixture of 1,3,5-triisopropylphenyl diisocyanate (TRIDI) and 2,6-diisopropylphenyl iisocyanate (DIPI) for CDI 2, 4, 5 and 6 or a mixture of 1,3,5-triisopropylphenyl diisocyanate (TRIDI) and cyclohexanol was carbodiimidized at 160 C. in the presence of about 0.1% methylphospholene oxide until an NCO content of <1% was achieved.

[0049] The results are listed in Table 1 below.

[0050] Tests were carried out on: [0051] 1) CDI 1: Polycarbodiimide having an NCN content of about 14% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=NCO and produced from 1,3,5-triisopropylphenyl diisocyanate (comparative example) [0052] 2) CDI 2: Polycarbodiimide having an NCN content of about 13.5% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=NCNR.sup.I where R.sup.I=2,6-diisopropylphenyl and produced from about 80% by weight 1,3,5-triisopropylphenyl diisocyanate and 20% by weight 2,6-diisopropylphenyl isocyanate (comparative example). [0053] 3) CDI 3: Polycarbodiimide having an NCN content of about 12.5% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=oxocyclohexyl and produced from about 80% by weight 1,3,5-triisopropylphenyl diisocyanate and 20% by weight cyclohexanol (comparative example). [0054] 4) CDI 4: Polycarbodiimide having an NCN content of about 14% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=NCNR.sup.I where R.sup.I=2,6-diisopropylphenyl and produced from about 92.5% by weight 1,3,5-triisopropylphenyl diisocyanate and 7.5% by weight 2,6-diisopropylphenyl isocyanate (comparative example). [0055] 5) CDI 5: Polycarbodiimide having an NCN content of about 14.5% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=oxocyclohexyl and produced from about 97% by weight 1,3,5-triisopropylphenyl diisocyanate and 3% by weight cyclohexanol (comparative example). [0056] 6) CDI 6: Polycarbodiimide having an NCN content of about 14% by weight, conforming to formula (I) with R.sup.1, R.sup.2, R.sup.3=isopropyl and R=NCNR.sup.I where R.sup.I=2,6-diisopropylphenyl and produced from about 97% by weight 1,3,5-triisopropylphenyl diisocyanate and 3% by weight 2,6-diisopropylphenyl isocyanate (inventive).

TABLE-US-00001 TABLE 1 Stability at 180 C., 4 h Proportion polymerization state, Pelletizability/pellet Mw in monomeric Ex. Carbodiimide solubility in toluene form g/mol carbodiimide 1 CDI 1 polymerized/partially difficult, formation of about <0.1% by (comp.) soluble threads/irregular 17 000 weight shape and size 2 CDI 2 no further very good, same about about 1.8-2% (comp.) polymerization/soluble shape and size 3000 by weight 3 CDI 3 polymerized/insoluble very difficult, no pellet about (comp.) form possible 9000 4 CDI 4 no further very good, same about about 0.35% (inv.) polymerization/soluble shape and size 8000 by weight 5 CDI 5 polymerized/insoluble not possible about (comp.) 12 000 6 CDI 6 no further good, same shape about <0.1% by (inv.) polymerization/soluble and size 15 000 weight comp .: comparative example, inv .: inventive

[0057] As is apparent from Table 1 only the inventive polycarbodiimide is capable of relatively easy and reliable production and finishing (no risk of runaway polymerization in the reactor or in the conduits to and in the finishing region such as a flake roller or pelletizing belt) and simultaneously shows the desired molar mass (Mw>10 000 g/mol) and a reduced proportion of toxic monomeric carbodiimide below the relevant limit of 0.1% by weight. The emission characteristics are moreover reduced with longer polymer chains and a low proportion of monomeric carbodiimide.

Hydrolysis Inhibition in Polyethylene Terephthalate (PBT)

[0058] To evaluate the hydrolysis inhibition in PET 2.5% by weight respectively of the carbodiimides investigated were dispersed into PET using a ZSK 25 laboratory twin screw extruder from Werner & Pfleiderer prior to the measurement described below. F3 standard test specimens for measurement of breaking strength were then produced from the resultant granulates in an Arburg Allrounder 320 S 150-500 injection-moulding machine.

[0059] For the hydrolysis test, these F3 standard test specimens were stored in water at a temperature of 120 C. and the breaking strength thereof was measured in MPa. Table 2 shows the relative breaking strengths=(breaking strength after x days of storage/breaking strength after 0 days)100. A lower limit for relative breaking strength is usually 70-75%.

[0060] The results are shown in Table 2:

TABLE-US-00002 Relative tear resistance Ex. 7: Hydrolysis without Ex. 8: Ex. 10: Ex. 11: Ex. 12: duration CDI CDI 1 Ex. 9: CDI CDI 3 CDI 4 CDI 6 (days) (comp.) (comp.) 2 (comp.) (comp.) (comp.) (inv.) 0 100% 100% 100% 100% 100% 100% 1 100% 100% 100% 100% 100% 100% 2 51% 100% 100% 100% 100% 100% 3 100% 100% 100% 100% 100% 4 100% 100% 100% 100% 100% 5 100% 48% 40% 100% 100% 6 100% 100% 100% 7 100% 75% 100% 8 100% 100% 9 69% 81% 10 comp. = comparative example, inv. = inventive

Dispersibility and Compatibility in Polyurethane-Based Formulations and in Rollable Polyurethane

[0061] Table 3 shows the results of the compatibility tests in DMF/polyurethane dispersions and in rollable polyurethane elastomer (Urepan, LANXESS Deutschland GmbH)

TABLE-US-00003 Proportion Dispersibility/solubility poly- M > 30 000 Rollable Ex. carbodiimide g/mol polyurethane DMF/PU dispersion 13 CDI 1 (comp.) 22 wt % very poor, no homogeneous and formation stable dispersion of spots 14 CDI 6 (inv.) 10 wt % homogeneous, homogeneous and no spots stable dispersion comp. = comparative example, inv. = inventive

[0062] As is apparent from Table 3, compared to the polycarbodiimide from the prior art the inventive polycarbodiimide invention leads to stable and homogeneous polyurethane formulations due to better dispersibility and solubility. It is also apparent that a lower proportion of higher molecular weight polymer chains of more than 30 000 g/mol in the inventive polycarbodiimide significantly improves compatibility in many applications and formulations.