Production and use of new thermoplastic polyurethane elastomers based on polyether carbonate polyols

Abstract

The invention relates to a method for producing a thermoplastic polyurethane elastomer based on polyether carbonate polyols. The method comprises a first step, in which at least A) an organic diisocyanate and B) a polyol having a number-average molecular weight Mn>=500 and <=5000 g/mol are reacted to form an isocyanate-terminated prepolymer. In a second step, the prepolymer is reacted with C) one or more chain extenders having a molecular weight>=60 and <=490 g/mol and optionally D) a monofunctional chain stopper or E) an organic diisocyanate, wherein optionally at least F) one catalyst is used in the first and/or second step.; The molar ratio of the sum of the isocyanate groups from A) and, if applicable, E) to the sum of the groups reactive to isocyanate in B), C), and, if applicable, D) is >=0.9:1 and <=12:1, and component B) contains at least one polyether carbonate polyol, which can be obtained by adding carbon dioxide and alkylene oxides to H-functional starter substances. The invention further relates to a thermoplastic polyurethane elastomer produced in accordance with the method according to the invention, the use of said thermoplastic polyurethane elastomer to produce extruded or injection molded items, and the items produced by extrusion or injection molding.

Claims

1. A process for the production of an injection-molded or extruded item comprising preparing a thermoplastic polyurethane elastomer by reacting, in a reactive extruder, in a first step, at least A) one organic diisocyanate comprising two isocyanate groups with B) one polyol with number-average molar mass M.sub.n ≧500 and ≦5000 g/mol, which has two isocyanate-reactive groups, to give an isocyanate-terminated prepolymer, and reacting, in a second step, the prepolymer with C) one or more chain extenders with molar mass ≧60 and ≦490 g/mol, which have two isocyanate-reactive groups, and optionally D) a monofunctional chain terminator which has an isocyanate-reactive group and/or optionally E) an organic diisocyanate comprising two isocyanate groups, where F) a catalyst is optionally used in the first and/or second step, the molar ratio of the entirety of the isocyanate groups from A) and optionally E) to the entirety of the isocyanate-reactive groups in B), C), and optionally D) is ≧0.9:1 and >1.2:1 and component B) comprises at least one polyether carbonate polyol obtainable via an addition reaction of carbon dioxide and a mixture of 75 to 100% by weight of propylene oxide and 0 to 25% by weight of ethylene oxide onto H-functional starter substances, and injection molding or extruding the thermoplastic polyurethane elastomer to produce the injection-molded or extruded item.

2. The process as claimed in claim 1, wherein in the second step the prepolymer is reacted only with C) one or more chain extenders with molar mass ≧60 and ≦490 g/mol, which have two isocyanate-reactive groups, and optionally D) a monofunctional chain terminator which has an isocyanate-reactive group and/or optionally E) an organic diisocyanate comprising two isocyanate groups.

3. The process as claimed in claim 1, wherein the polyether carbonate polyol is obtainable via an addition reaction of carbon dioxide and propylene oxides onto H-functional starter substances with the use of multimetal cyanide catalysts.

4. The process as claimed in claim 1, wherein the content of carbonate groups, calculated as CO.sub.2 in the polyether carbonate polyol is ≧3 and ≦35% by weight.

5. The process as claimed in claim 1, wherein the number-average molar mass M.sub.n of the poly ether carbonate polyol is ≧500 and ≦10000 g/mol.

6. The process as claimed in claim 1, wherein the average OH functionality of the polyether carbonate polyol is ≧1.85 and ≦2.5.

7. The process as claimed in claim 1, wherein the organic diisocyanate A) comprises at least one aromatic diisocyanate.

8. The process as claimed in claim 1, wherein component B) comprises at least one polyether carbonate polyol and at least one polyether polyol.

9. The process as claimed in claim 1, wherein component B) comprises at least one polyether carbonate polyol and at least one polyester polyol.

10. The process as claimed in claim 1, wherein component B) comprises at least one polyether carbonate polyol and at least one polycarbonate polyol.

11. The process as claimed in claim 1, wherein component B) comprises two polyether carbonate polyols that differ from one another.

12. The process as claimed in claim 1, wherein component C) comprises diols, diamines, or diol/diamine mixtures.

13. An injection-molded or extruded item obtained by the process as claimed in claim 1.

14. The process as claimed in claim 1, wherein the organic diisocyanate A) comprises at least one aromatic diisocyanate, wherein the content of carbonate groups, calculated as CO.sub.2 in the polyether carbonate polyol is ≧3 and ≦35% by weight, and wherein component C) comprises a diol.

15. The process as claimed in claim 1, wherein the molar ratio of the isocyanate groups from A) to the groups in B) reactive toward isocyanate is from 1.1:1 to 5:1.

16. The process as claimed in claim 1, wherein the average OH functionality of the polyether carbonate polyol is ≧1.97 and ≦2.03.

17. The process as claimed in claim 1, wherein the proportion ofpolyether carbonate polyols, based on the total mass of component B), is ≧20 and ≦100% by weight.

Description

EXAMPLES

(1) The following methods were used to characterize the polymeric polyols used:

(2) The CO.sub.2 content incorporated within the polyether carbonate polyols was determined by means of .sup.1H NMR (Bruker, DPX 400, 400 MHz; pulse program zg30, delay d1: 5 s, 100 scans). In each case the sample was dissolved in deuterated chloroform. Internal standard added to the deuterated solvent comprised dimethyl terephthalate (2 mg for every 2 g of CDCl.sub.3). The relevant resonances in the .sup.1H NMR (based on CHCl.sub.3=7.24 ppm) are as follows:

(3) Carbonates, resulting from carbon dioxide incorporated within the polyether carbonate polyol (resonances at from 5.2 to 4.8 ppm) PO not consumed in the reaction with resonance at 2.4 ppm, polyether polyol (i.e. without incorporated carbon dioxide) with resonances at from 1.2 to 1.0 ppm.

(4) The molar content of the carbonate incorporated within the polymer, of the polyether polyol fractions, and also of the PO not consumed in the reaction are determined via integration of the corresponding signals.

(5) All of the number-average molar masses M.sub.n stated in the description and in the examples for the polymeric polyols were determined as follows: the OH number was first determined experimentally via esterification followed by back-titration of the excess esterification reagent with standard alcoholic potassium hydroxide solution in accordance with DIN 53240-2. The OH number is stated in mg KOH per gram of polyol. The number-average molar mass can be calculated from the OH number by way of the following formula: number-average molar mass M=56×1000×OH functionality/OH number. The present examples assume OH functionality F to be approximately 2.0.

(6) In the case of low-molecular-weight polyols with defined structure, the molar mass is calculated from the molecular formula.

(7) Production of TPUs 1 to 7

(8) Stage 1)

(9) The appropriate polyol (at 190° C.) and the diphenylmethane 4,4′-diisocyanate (MDI) at 60° C. were reacted, with stirring, as in table 1 in a reaction vessel. In all of the examples 1 to 18 the reaction was catalyzed with 20 ppm (based on the polyol) of Tyzor® AA 105 (Dorf Ketal) (except in the case of examples 17 and 18; these used 50 ppm of Desmorapid®SO from Bayer Material Science AG, Leverkusen (tin(11) 2-ethylhexanoate)). In all of the experiments, concomitant use was also made of 1% of Licowax® C (Clariant) as mold-release agent (except in the case of examples 17 and 18; these used 0.3% by weight of Loxiol®3324 from Emery Oleochemicals, Düsseldorf) and 0.3% by weight of Irganox® 1010 (BASF SE) as antioxidant. The reaction mixture reached a temperature maximum (prepolymer formation). After about 60 sec. of reaction time, the procedure was continued with stage 2. Operations in examples 19 to 21 were analogous to those of example 17, but without catalyst and additionally with 0.045% by weight of Wacker®AK1000 silicone oil from Wacker Chemie AG and 0.185% by weight of Tinuvin®PUR866 from BASF SE.

(10) Stage 2)

(11) The 1,4-butanediol, heated to 60° C., was added in one portion to the prepolymer mixture of stage 1, and incorporated by mixing with vigorous stirring. After about 10 to 15 seconds, the reaction mixture was poured onto a coated metal sheet and subjected to postconditioning at 80° C. for 30 minutes, After cooling, this gave a cast TPU sheet.

(12) Production of TPU 8 with the Molar Data of Table 1

(13) Stages 1 and 2

(14) A prepolymer was produced from polyol No. 2 and MDI as in examples 1 to 7. The resultant prepolymer was then further reacted with polyol No. 1 and 1,4-butanediol. The reaction mixture was poured onto a coated metal sheet and subjected to postconditioning at 80° C. for 30 minutes. After cooling, this gave a cast TPU sheet.

(15) Table 1 describes the components used, and proportions thereof, for the production of the TPUs.

(16) TABLE-US-00001 TABLE 1 Molar proportions of the starting components for the synthesis of the TPUs Polyol MDI 1,4-Butanediol Example Polyol No. [mol] [mol] [mol] 1* 1 1 4 3 2  2 1 4 3 3* 3 1 4 3 4  4 1 6.6 5.6 5* 5 1 6.6 5.6 6* 1 and 5 0.5 + 0.5 5.3 4.3 7  6 1 5.3 4.3 8  2 and 1 0.67 + 0.33 4 3 *comparative example not of the invention

(17) Polyol 1: Acclaim®2200 (polypropylene oxide glycol with OH number 56.7 mg KOH/g (M.sub.n=1979 g/mol, from Bayer MaterialScience AG).

(18) Polyol 2: Polyether carbonate diol based on propylene oxide and CO.sub.2 with OH number 58.2 mg KOH/g (M.sub.n=1928 g/mol) and with 15.1% by weight incorporated CO.sub.2 content.

(19) Polyol 3: Polyether carbonate diol with OH number 60.9 mg KOH/g (M.sub.n=1842 g/mol) obtained via reaction of a polypropylene oxide glycol with OH number 522 mg KOH/g with diphenyl carbonate with elimination of phenol.

(20) Polyol 4: Polyether carbonate diol based on propylene oxide and CO.sub.2 with OH number 28.5 mg KOH/g (M.sub.n=3937 g/mol) and with 19.0% by weight incorporated CO.sub.2 content.

(21) Polyol 5: Acclaim®4200 (polypropylene oxide glycol with OH number 28.9 mg KOH/g (M.sub.n=3882 g/mol, from Bayer MaterialScience AG).

(22) Polyol 6: Polyether carbonate diol based on propylene oxide and CO.sub.2 with OH number 37.7 mg KOH/g (M.sub.n=2976 g/mol) and with 17.5% by weight incorporated CO.sub.2 content.

(23) Studies on TPUs 1 to 8:

(24) The resultant cast TPU sheets were chopped and granulated. The granulated material was processed in an Arburg Allrounder 470S injection-molding machine in a temperature range from 180 to 230° C. and in a pressure range from 650 to 750 bar with an injection flow rate of from 10 to 35 cm.sup.3/s to give bars (mold temperature: 40° C.; bar size: 80×10×4 mm) and sheets (mold temperature: 40° C.; size: 125×50×2 mm).

(25) The following test methods were used:

(26) Hardness was measured in accordance with DIN 53505, abrasion was measured in accordance with DIN ISO 4649-A, and the tensile test was carried out in accordance with ISO 37.

(27) Dynamic mechanical analysis (DMA: storage-tensile modulus of elasticity):

(28) Rectangles (30 mm×10 mm×2 mm) were punched out from the injection-molded sheets. These test sheets, under constant preload—where appropriate dependent on the storage modulus—were subjected to periodic excitation with very small deformations, and the force acting on the clamp system was measured as a function of the temperature and excitation frequency.

(29) The preload additionally applied serves to retain adequate clamping of the sample when deformation amplitude is negative.

(30) The DMA measurements were taken using a Seiko DMS 210 at 1 Hz in the temperature range from −150° C. to 200° C. with a heating rate of 2° C./min.

(31) The behavior of the invention under warm conditions was characterized by measuring and stating the storage-tensile modulus of elasticity at +20° C. and at +60° C., for comparison.

(32) Heat resistance is characterized by stating the temperature at which the value is less than 2 MPa, i.e. the injection-molded part no longer retains a stable shape. The higher the temperature value, the more stable the TPU.

(33) Table 2 describes the properties determined for the TPUs 1 to 8.

(34) TABLE-US-00002 TABLE 2 Results Example 1* 2 3* 4 5* 6* 7 8 Immediate hardness [Shore A] 83 85 90 75 64 74 82 86 Abrasion [mm.sup.3] 83 38 132 207 249 180 139 71 100% modulus [MPa] 6.4 9.7 11.9 4.9 3.0 4.3 7.0 7.8 300% modulus [MPa] 10.3 15.9 14.7 7.9 5.5 7.5 11.3 12.3 Tensile strength [MPa] 22.2 32.2 16.9 10.4 8.0 12.6 19.3 24.1 Tensile strain value [%] 651 553 496 775 793 857 649 596 DMA measurement: Modulus of elasticity (20° C.) [MPa] 26 120 51 18 6 10 32 33 Modulus of elasticity (60° C.) [MPa] 17 31 18 10 5 9 16 18 T (2 MPa) [° C.] 139.3 145.3 137.2 119.8 110.8 120.1 136.8 143 *comparative example not of the invention

(35) When the TPUs of the invention from examples 2 and 8 are compared with the respective examples (1 and 3) not of the invention, they have similarly high hardness by virtue of the identical molar quantity of chain extender and therefore hard segments. The TPUs of the invention from examples 2 and 8 moreover have a markedly better level of mechanical properties than the respective comparative products (examples 1 and 3), this being particularly apparent from the tensile strength. The abrasion values of the TPUs of the invention from examples 2 and 8 are likewise markedly lower than the abrasion values of the comparative TPUs.

(36) The two other TPUs of the invention from examples 4 and 7 also have a better level of mechanical properties and better abrasion values than the respective comparative examples 5 and 6.

(37) The modulus of elasticity value measured by DMA at ±20° C. and at +60° C. are markedly higher for examples 2, 4, 7, and 8 of the invention than for the corresponding comparative examples 1, 3, 5, and 6, as also is the temperature at which a minimum stress of 2 MPa is retained. At high temperatures, the TPUs of the invention are therefore markedly more heat-resistant than the comparative TPUs.

(38) Table 3 below describes the components used, and proportions thereof, for the production of TPU 9 to TPU 21.

(39) TABLE-US-00003 TABLE 3 Molar proportions of the starting components for the synthesis of the TPUs Polyol MDI 1,4-Butanediol Example Polyol No. [mol] [mol] [mol]  9* 1 1 4.08 3 10 7 1 4.08 3 11 8 1 4.08 3 12 1 and 7 0.1 + 0.9 4.08 3 13 1 and 7 0.25 + 0.75 4.08 3 14 1 and 7 0.5 + 0.5 4.08 3 15 1 and 7 0.75 + 0.25 4.08 3 16 1 and 7 0.9 + 0.1 4.08 3  17* 9 1 2.35 1.3 18  9 and 11 0.67 + 0.33 2.35 1.3  19*  9 and 10 0.67 + 0.33 7.36 6.22 20 11 and 10 0.67 + 0.33 7.36 6.22 21 9 and 7 0.67 + 0.33 7.36 6.22 *comparative example not of the invention

(40) Polyol 7: Polyether carbonate diol based on 1,2-propanediol, propylene oxide and CO.sub.2 with OH number 55.5 mg KOH/g (M.sub.n=2022 g/mol) and with 18.8% by weight incorporated CO.sub.2 content.

(41) Polyol 8: Polyether carbonate diol based on 1,2-propanediol, propylene oxide and CO.sub.2 with OH number 59.8 mg KOH/g (M.sub.n=1876 g/mol) and with 24.7% by weight incorporated CO.sub.2 content.

(42) Polyol 9: Terathane® 1000, polytetramethylene glycol from Invista with OH number 114,4 mg KOH/g, (M.sub.n=981 g/mol).

(43) Polyol 10: Terathane® 2000, polytetramethylene glycol from Invista with OH number 55.0 mg KOH/g (M.sub.n=2040 g/mol).

(44) Polyol 11: Polyether carbonate diol based on 1,2-propanediol, propylene oxide and CO.sub.2 with OH number 115.5 mg KOH/g (M.sub.n=971 g/mol) and with 15.4% by weight incorporated CO.sub.2 content.

(45) The TPUs produced from examples 9 to 21 were processed as described above examples 1 to 8), and the mechanical properties were determined. The values found are listed in table 4 below.

(46) TABLE-US-00004 TABLE 4 Results of examples 9 to 21 TPU Tensile from Hardness 100% 300% Tensile strain example [Shore modulus modulus strength value No. A/D] [MPa] [MPa] [MPa] [%]  9* 83A 5.0 8.4 16.8 729 10 88A 10.4 17.3 35.5 583 11 94A 16.0 24.1 34.2 506 12 82A 8.3 14.6 31.0 586 13 84A 7.7 13.4 32.4 610 14 83A 6.6 11.7 27.8 621 15 84A 6.5 11.5 27.4 623 16 84A 6.2 11.2 28.1 625  17* 86A 7.4 15.9 38.2 417 18 85A 7.6 14.7 38.8 474  19* 66D 31.1 — 36.2 219 20 72D 35.6 44.8 45.3 308 21 69D 32.5 41.6 41.6 310 *comparative example not of the invention

(47) When the TPUs of the invention from examples 10 and 11 are compared with the comparative TPU from example 9, they have higher hardness and markedly higher mechanical strength values (modulus values and tensile strength). Although the tensile strain value is somewhat smaller than for the TPU from example 9, it remains very good: above 500%.

(48) When the TPUs of the invention from examples 12 to 16 are compared with the comparative TPU from example 9 they have similarly high hardness, but a markedly higher level in mechanical properties (modulus values and tensile strength) with very good tensile strain value, although the quantity of polyether carbonate diol used concomitantly in test 16 was only 10 mol %.

(49) When the TPUs of the invention from example 18 is compared with the comparative TPU from example 17 it has comparable hardness and an almost identical level of mechanical properties, but the tensile strain value of the TPU of the invention is markedly better.

(50) When the TPUs of the invention from examples 20 and 21 are compared with the comparative TPU from example 19, they have somewhat higher hardness, but a markedly higher level of mechanical properties (modulus values and tensile strength), and also a markedly higher tensile strain value.