PROCESS FOR PREPARING A POLYURETHANE USING A POLYESTER POLYOL COMPRISING POLYCYCLIC AROMATIC MOIETIES

Abstract

The present invention is directed to a polyisocyanate polyaddition product, obtained or obtainable according to a process containing reacting at least a polyisocyanate composition (C-I) comprising at least one polyisocyanate; and a composition (C-II) comprising at least one compound (C-A) having at least two functional groups which are reactive towards isocyanate groups, wherein the compound (C-A) has a molecular weight of 500 g/mol or more and comprises polycyclic aromatic moieties. The present invention is further directed to a process for preparing said polyisocyanate polyaddition product and the use thereof in a cable, conveyor belt, roller, seal for gasket or railway pad.

Claims

1-13. (canceled)

14. A polyisocyanate polyaddition product, obtained by a process comprising: reacting at least a polyisocyanate composition (C-I) comprising polyisocyanate and a composition (C-II) comprising a compound (C-A) having at least two functional groups which are reactive towards isocyanate groups, wherein the compound (C-A) has a molecular weight of 500 g/mol or more and comprises polycyclic aromatic moieties, thereby producing a first product, and reacting the first product with a compound (CC) having at least two functional groups which are reactive towards isocyante groups as a chain extender, wherein the compound (CC) has a molecular weight ranging from 49 g/mol to 499 g/mol.

15. The polyisocyanate polyaddition product according to claim 14, wherein the polycyclic aromatic moieties of the compound (C-A) comprise fused aromatic rings.

16. The polyisocyanate polyaddition product according to claim 14, wherein the compound (C-A) is a polyol.

17. The polyisocyanate polyaddition product according to claim 14, wherein the compound (C-A) is a polyol selected from the group consisting of a polyester, a polyether and a polycarbonate.

18. The polyisocyanate polyaddition product according to claim 14, wherein the polyisocyanate is an aromatic polyisocyanate.

19. The polyisocyanate polyaddition product according to claim 14, wherein the compound (CC) comprises aromatic moieties.

20. The polyisocyanate polyaddition product according to claim 14, wherein the compound (CC) is 1,4-benzenedimethanol.

21. A process for preparing a polyisocyanate polyaddition product, the process comprising: reacting at least a polyisocyanate composition (C-I) comprising polyisocyanate and a composition (C-II) comprising a compound (C-A) having at least two functional groups which are reactive towards isocyanate groups, wherein the compound (C-A) has a molecular weight of 500 g/mol or more and comprises polycyclic aromatic moieties, thereby producing a first product, and reacting the first product with a compound (CC) having at least two functional groups which are reactive towards isocyante groups as a chain extender, wherein the compound (CC) has a molecular weight ranging from 49 g/mol to 499 g/mol.

22. An article, comprising the polyisocyanate polyaddition product according to claim 14.

23. The article according to claim 22, wherein the article is a cable, a conveyor belt, a roller, a seal for a gasket or a railway pad.

24. A method for producing an article, the method comprising: employing the polyisocyanate polyaddition product according to claim 14, wherein the article is a cable, a conveyor belt, a roller, a seal for a gasket or a railway pad.

Description

EXAMPLES AND COMPARATIVE EXAMPLES

1. Compounds Used

[0559]

TABLE-US-00001 C.sub.4 to C.sub.12 aliphatic dicarboxylic acid Adipic acid C.sub.10 to C.sub.14 aromatic diol 1,5-dihydroxynaphthalene C.sub.2 to C.sub.4 alkylene oxide propylene oxide butylene oxide C.sub.2 to C.sub.10 diol/low molecular weight polyfunctional 1,4-butanediol(BDO) compound reactive towards isocyanate molecular weight: 90.12 g/mol C.sub.6 to C.sub.14 alkylaryl diol 1,4-benzendimethanol (BDM) molecular weight: 138.16 g/mol KOH Tin tetrabutoxid Tin octoate Titanium(IV) butoxide (CAS: 5593-70-4 (TTB)) Tin(II) 2-ethylhexanoate (CAS: 301-10-0 (SDO)) are available from Sigma Aldrich Secondary polyol Lupraphen 6607/1 (polyester polyol) Isocyanate Lupranat M20 (polymeric MDI) Polyether based TPU Elastollan 1195A Polyisocyanate Lupranat MET (4,4-MDI) Polyester based polyol Elastollan PESOL (adipate ester) Tetra hydrofuran PolyTHF 1000, PolyTHF2000 Additive Elastostab H01 (hydrolysis stabilizer) are available from BASF

2. Standard Methods

[0560]

TABLE-US-00002 Weight average molecular weight DIN 55672-1 Viscosity (at 25 C.) DIN EN ISO 3219 T.sub.g DIN EN ISO 11357-1 at 20 K/min OH value DIN 53240 Shore hardness ASTM D2240 Tensile strength DIN 53504 Elongation at break DIN 53504 Compression set ASTM D395 Creep resistance DIN EN ISO 899-1

3. Synthesis of alkoxylated dihydroxynaphthalene

3.1 Example 1

1,5-dihydroxynaphthalene propoxylate

[0561] A 300 mL pressure reactor provided with stirrer, jacket heating and cooling, metering facility for alkylene oxide was made inert in nitrogen atmosphere and heated to 140 C. A mixture comprising 32 g of 1,5-dihydroxynaphthalene and 1.20 g of KOH (50 wt. % aqueous solution) was added to the reactor and kept at 140 C. 168 g of propylene oxide was added to the mixture over a period of 3 h and 8 min to obtain a reaction mixture. The reaction mixture was allowed to react for 3 h at 140 C., followed by stripping with nitrogen for 20 min and then cooling down to 40 C. Workup done with macrosorb. 181 g of 1,5-dihydroxynaphthalene propoxylate as a brownish oil having an OH number of 156 mg KOH/g and a viscosity of 699 mPa.Math.s at 25 C. was obtained.

3.2 Example 2

1,5-dihydroxynaphthalene ethoxylate

[0562] A 300 mL pressure reactor provided with stirrer, jacket heating and cooling, metering facility for alkylene oxide was made inert in nitrogen atmosphere and heated to 140 C. A mixture comprising 62.55 g of 1,5-dihydroxynaphthalene, 50 g of toluene and 1.20 g of KOH (50 wt. % aqueous solution) was added to the reactor and kept at 140 C. 136.9 g of ethylene oxide was added to the mixture over a period of 5 h and 20 min to obtain a reaction mixture. The reaction mixture was allowed to react for 2 h at 140 C., followed by stripping with nitrogen for 20 min and then cooling down to 40 C. The unreacted toluene was removed on rotavap and workup was done with macrosorb. 189 g of 1,5-dihydroxynaphthalene ethoxylate as a brownish oil having an OH number of 241 mg KOH/g and a viscosity of 2310 mPa.Math.s at 25 C. was obtained.

4. Synthesis of polyester polyol (PESOL)

4.1 PESOL 1

[0563] In a 4 L round-bottom flask, a mixture comprising 1138 g adipic acid, 607.73 g of 1,4-butanediol, 611 g of 1,5-dihydroxynaphthalene propoxylate (from example 1), 1 ppm tin tetrabutoxid and 5 ppm of tin octoate were added. The mixture was heated to 200 C. for 3 h with stirring and left for 25 h. Water formed during the reaction was continuously removed by distillation. PESOL 2 as a brownish oil having an OH number of 54 mg KOH/g, acid number of 0.8 mg KOH/g and viscosity of 707 mPa.Math.s at 25 C. was obtained.

4.2 PESOL 2

[0564] In a 4 L round-bottom flask, a mixture comprising 1037 g adipic acid, 607.73 g of 1,4-butanediol, 611 g of 1,5-dihydroxynaphthalene ethoxylate (from example 2), 1 ppm tin tetrabutoxid and 5 ppm of tin octoate were added. The mixture was heated to 220 C. for 3 h with stirring and left for 20 h. Water formed during the reaction was continuously removed by distillation. PESOL 1 as a yellowish oil having an OH number of 53 mg KOH/g, acid number of 1.8 mg KOH/g and viscosity of 1250 mPa.Math.s at 25 C. was obtained.

5. General description of thermoplastic polyurethane synthesis

5.1 TPU 1 (Comparative)

[0565] In a 2 L metal container, 800 g of Lupraphen 6607/1 and 164.59 g of 1,4-butanediol was mixed with a mechanical stirrer under a constant flow of nitrogen. The container was then subsequently covered and placed inside a hot air oven preheated at 100 C. The preheated mixture was taken out of the oven and 6.4 g of Elastostab H01 was added followed by stirring. In a separate vessel, Lupranat M20 was heated to a temperature of 45 C. Once the temperature of the mixture reached 80 C., 560 g of preheated Lupranat was added and the mixture stirred at 200 rpm. Due to the exothermic reaction, the mixture was poured into a teflon frame kept over a hot plate having a temperature of 125 C. to obtain a TPU slab. Once the TPU slab turned solid, it was removed from the hot plate and subsequently annealed inside a hot oven at 80 C. for 24 h. The TPU was allowed to cool gradually, followed by milling in a miller and thereafter shredded to small granulates. The granulates were dried at 110 C. for 3 h and then injection molded to test plaques of size 2mm6mm. The test plaques were then used to determine the mechanical performance as provided in Table 2.

5.2 Further Examples were Conducted with the Above Process Conditions, Except that the Present Invention polyester polyol was now Used

[0566]

TABLE-US-00003 TABLE 1 TPU compositions Polyester Hard segment Polyester Secondary polyol:secondary fraction T.sub.g TPU polyol polyol polyol [%] ( C.) TPU 1 Lupraphen 40.89 20 (comparative) 6607/1 TPU 2 PESOL 1 Lupraphen 10:90 40.89 15 6607/1 TPU 3 PESOL 1 Lupraphen 20:80 40.89 15 6607/1 TPU 4 PESOL 2 Lupraphen 10:90 40.89 15 6607/1 TPU 5 PESOL 2 Lupraphen 20:80 40.89 15 6607/1

[0567] The above TPUs were checked for their mechanical performance and the results provided hereinbelow in Table 2.

TABLE-US-00004 TABLE 2 Mechanical performance of different TPUs Tensile strength Elongation Compression set Shore [MPa] at break [%] hardness 72 h/23 C./ 24 h/70 C./ TPU [Shore D] 25 C. 80 C. [%] 25 C. 80 C. [%] 30 min 30 min TPU 1 51 56 44 21 530 910 72 22 35 (comparative) TPU 2 51 49 44 10 520 1190 129 22 33 TPU 3 50 50 48 4 470 1070 128 18 35 TPU 4 51 49 43 12 490 1040 112 20 35 TPU 5 51 49 41 16 490 1070 118 25 41

[0568] As evident from table 2, the polyester polyol of the present invention imparts the TPU with improved tensile strength and elongation at break. The TPUs incorporating different amounts of alkoxylated dihydroxynaphthalene based PESOL resulted in less than 20% decrease in the tensile strength values and more than 100% increase in the elongation at break when measured at elevated temperature i.e. 80 C. In fact, the 4% decrease in the tensile strength for TPU 3 confirms that the present invention TPU can withstand high loads without undergoing much deformation. Moreover, the compression set values of the present invention TPUs do not vary much in comparison to TPU 1 (comparative). These improvements may be attributed to the incorporation of the naphthalene motif i.e. alkoxylated dihydroxynaphthalene as a backbone in the soft segment of the TPU, which provide the additional - stacking and strengthen their performance.

[0569] On the contrary, TPU 1 (comparative) showed more than 20% decrease in the tensile strength and 72% increase in the elongation at break at elevated temperature, thereby confirming comparably inferior performance characteristics in view of the present invention TPUs.

[0570] Thermal resistance of the TPUs were also checked and compared with commercially available TPU. To do so, the temperature was kept at 165 C. for 2500 h (see Table 3).

TABLE-US-00005 TABLE 3 Thermal resistance performance of different TPUs Temperature Elongation at break TPU [ C.] Before ageing After ageing TPU 1 (comparative) 165 740 <50% Elastollan 1195A 165 500 Melted TPU 3 165 470 >50% TPU 5 165 460 >50%

[0571] For auto cable operations, it is desired that the elongation at break after ageing should be >50%. Neither the polyester based (TPU 1) nor the polyether based (Elastollan 1195A) TPU can achieve the desired elongation at break. Thus, the present invention TPUs show better thermal resistance performance than the other available TPUs.

TABLE-US-00006 TABLE 3 Creep resistance performance of different TPUs TPU Delta L.sub.z value TPU 1 (comparative) 8.2 Elastollan 1195A 11.8 TPU 3 5.3 TPU 5 5.6

[0572] The Delta L.sub.z values represent the difference in elongation in length values. Since the creep performance illustrates the deformation of the TPU, a small value of Delta Lz represents better resistance to creep. Therefore, as evident in table 3, the present invention TPUs have substantially better creep resistance in comparison to the other available polyester (TPU 1) and polyether (Elastollan 1195A) based TPUs.

6. Synthesis of polyester polyol (PESOL)

[0573] In a 4 L round-bottom flask, a mixture comprising 1613.3 g adipic acid, 775.2 g of 1,4-butanediol, 509 g of 1,4-benzenedimethanol, 1 ppm titanium(IV) tetrabutoxid and 5 ppm of Tin(II) 2-ethylhexanoate were added. The mixture was heated to 200 C. for 3 h with stirring. The reaction temperature was increased 240 C. and left for 25 h. Water formed during the reaction was continuously removed by distillation. A vacuum pressure of 60mbar was applied to drive the reaction complete. PESOL as a brownish oil having an OH number of 55 mg KOH/g, acid number of 1.09 mg KOH/g and viscosity of 1138 mPa.Math.s at 75 C. was obtained.

7. One-Shot Process for thermoplastic polyurethane synthesis

[0574] In a 2 L metal container, polyol and chain extender were mixed with a mechanical stirrer under a constant flow of nitrogen. The container was then subsequently covered and placed inside a hot air oven preheated at 100 C. to 120 C. The preheated mixture was taken out of the oven and 6.4 g of Elastostab H01 was added followed by stirring. In a separate vessel, polyisocyanate was heated to a temperature of 45 C. Once the temperature of the mixture reached 80 C., preheated polyisocyanate was added and the mixture stirred at 200 rpm. Due to the exothermic reaction, the mixture was poured into a teflon frame kept over a hot plate having a temperature of 125 C. to obtain a TPU slab. Once the TPU slab turned solid, it was removed from the hot plate and subsequently annealed inside a hot oven at 80 C. for 24 h. The TPU was allowed to cool gradually, followed by milling in a miller and thereafter shredded to small granulates. The granulates were dried at 110 C. for 3 h and then injection molded to test plaques of size 2mm6mm. The test plaques were then used to determine the mechanical performance as provided in Table 6.

[0575] Further examples, both comparative and inventive, were conducted with the above process conditions having the below mentioned composition.

TABLE-US-00007 TABLE 4 TPU compositions for one-shot process Chain Hard segment T.sub.g TPU Polyol extender Polyisocyanate fraction ( C.) TPU 1a 750 g 182 g 529.25 g 0.35 30 PolyTHF 1000 BDM Lupranat MET CE 1a 700 g 169.36 g 648.55 g 0.35 40 PolyTHF 1000 BDO Lupranat MET TPU 2a 1000 g 163.3 g 426.2 g 0.29 20 Elastollan PESOL BDM Lupranat MET CE 2a 1000 g 121.53 g 470 g 0.29 30 Elastollan PESOL BDO Lupranat MET TPU 3a 200 g 163.2 g 425.47 g 0.29 10 PESOL + 800 g BDM Lupranat MET Elastollan PESOL CE 3a 200 g 121.47 g 467.2 g 0.29 15 PESOL + 800 g BDO Lupranat MET Elastollan PESOL

8. Two-Shot or pre-polymer Process for Cast polyurethane synthesis

[0576] Polyol was mixed with polyisocyanate at a temperature of 50 C. to obtain a polymeric mixture. The polymeric mixture was heated to 80 C. and stirred under nitrogen at this temperature for 2 h. The reaction temperature was monitored by a thermo element PT100. The resulting pre-polymer was cooled to room temperature.

[0577] The chain extender was now melted to 120 C. The above pre-polymer was heated to 80 C. for 2 h and then mixed with the melted chain extender at a temperature of 130 C.

[0578] Subsequent casting into a mold with a temperature of 125 C. lead to the resulting samples. After annealing at 125 C. and further annealing at 110 C. for 16 h yielded the final test plaques. The test plaques were then used to determine the mechanical performance as provided in Table 6.

[0579] Comparative samples were obtained in a similar manner as above, except that while mixing the melted chain extender with the pre-polymer there was no further heating provided. The composition of CPU samples, both inventive and comparative, are mentioned hereinbelow:

TABLE-US-00008 TABLE 5 CPU compositions for two-shot or pre-polymer process Pre-polymer NCO Chain CPU Polyol Polyisocyanate [%] extender CPU 1a 658 g 342 g 5.88 117 g PolyTHF 1000 Lupranat MET BDM CPU 2a 697 g 303 g 7.30 117 g PolyTHF 2000 Lupranat MET BDM CE 4a 573 g 427 g 9.43 117 g PolyTHF 1000 Lupranat MET BDO

[0580] The TPUs obtained from the one-shot process and the CPUs obtained from the two-shot process were checked for their mechanical performance and the results provided hereinbelow in Table 6.

TABLE-US-00009 TABLE 6 Mechanical performance of different polyurethanes Compression set Shore [%] hardness 72 h/23 C./ 24h/70 C./ 24 h/100 C./ Polyurethane [Shore A] 30 min 30 min 30 min CE 1a 98 26 46 76 TPU 1a 98 18 32 46 CE 2a 85 23 36 50 TPU 2a 85 18 24 33 TPU 3a 85 24 34 36 CE 3a 85 24 35 52 CE 4a 94 25 41 45 CPU 1a 96 18 21 27 CPU 2a 93 11 16 24

[0581] The importance of the low molecular weight aromatic diol (BDM), as a chain extender as well as in the polyol, is evident from Table 3. The presence of BDM as a chain extender in the inventive examples resulted in a substantial decrease in the compression set values over a wide range of temperature. In fact, the compression set value (at 100 C.) in case of CPU 2a dropped to 46% in comparison to CE 3a. Such a material is very desirable for application in areas operating under a wide range of temperature such as automotive application, manufacturing industry, etc. The the polyurethane materials of the present invention overcome the need of replacing the TPUs or CPUs every time the temperature shoots up, thereby resulting in cost saving.

[0582] CE 3a although makes use of BDM as a diol in the PESOL, the chain extender used therein is BDO. The presence of BDM as a chain extender is important as it provides the required - stacking which is inherent of the aromatic backbone. In the absence of the said aromatic backbone by means of the present invention chain extender (i.e. BDM), the final TPU obtained did not report any change in the compression set value which implies that the deformation in the said TPU remains the same (compare CE 2 and CE 3) over the wide range of temperature.

LITERATURE CITED

[0583] AU 2011335151

[0584] U.S. Pat. No. 5,574,092

[0585] Der-Jang Liaw, Die Angewandte Makromolekular Chemie. 1997, 245, 89-104