THERMOPLASTIC POLYURETHANE FROM RECYCLED RAW MATERIALS

Abstract

The present invention relates to a process for producing a thermoplastic polyurethane reacting at least one thermoplastic polyurethane (TPU-1) or a polyurethane mixture comprising a thermoplastic polyurethane (TPU-1) with at least one compound (V1) comprising two hydroxyl groups to obtain a mixture (G-a) comprising a thermoplastic polyurethane (TPU-2) and the reaction of the mixture (G-a) with a mixture (G-b) comprising an isocyanate composition (ZI) comprising at least one diisocyanate and optionally and a polyol composition (ZP) comprising at least one polyol (P2) to obtain a thermoplastic polyurethane (TPU target), wherein the proportion of the employed components (ZI) and (ZP) is matched to the hard segment content of the employed thermoplastic polyurethane (TPU-1), (V1) and the hard segment content of the thermoplastic polyurethane (TPU target). The invention further relates to a thermoplastic polyurethane obtained or obtainable by such a process and to the use thereof for producing extruded, injection molded and pressed articles as well as foams, cable sheathings, hoses, profiles, drive belts, fibers, nonwovens, films, moldings, soles, sporting goods, shoes, plugs, housings, damping elements for the electricals industry, automotive industry, mechanical engineering, 3D printing, medicine and consumer goods.

Claims

1-23. (canceled)

24. A process for producing a thermoplastic polyurethane, the process comprising: (a) reacting a thermoplastic polyurethane (TPU-1) or a polyurethane mixture comprising TPU-1 with a compound (VI) having two hydroxyl groups to obtain a mixture (G-a) comprising a thermoplastic polyurethane (TPU-2), wherein an average molecular weight of TPU-2 is less than an average molecular weight of TPU-1; and (b) reacting G-a with a mixture (G-b) comprising an isocyanate composition (ZI) comprising a diisocyanate and optionally a polyol composition (ZP) comprising a polyol (P2) to obtain a thermoplastic polyurethane (TPU-target), wherein a proportion of ZI and ZP is matched to a hard segment content of TPU-1, V1 and a hard segment content of TPU-target, and a proportion of ZI, ZP and V1 is matched to the hard segment content of TPU-1 via formula (1):
HSC.sub.G-c=(HSC.sub.TPU-targetw.sub.TPU-1*HSC.sub.TPU-1)/(1w.sub.TPU-1) (1), where HSC.sub.G-c=a hard segment content of a mixture (G-c), wherein G-c=G-b+V1, HSC.sub.TPU-target=a hard segment content of the obtained TPU-target, w.sub.TPU-1=a mass fraction of TPU-1, based on a total mass of TPU-1 and G-c, and HSC.sub.TPU-1=the hard segment content of TPU-1.

25. The process of claim 24, wherein V1 is selected from the group consisting of diols (Dl) having a number-average molecular weight <500 g/mol and polyols (P1) having a number-average molecular weight >500 g/mol, and in formula (1), HSC.sub.G-c=the hard segment content of G-c, wherein G-c=G-b+V1=G-b+D1+Pl.

26. The process of claim 24, wherein the average molecular weight of TPU-2 is less than 50% of the average molecular weight of TPU-1.

27. The process of claim 24, wherein TPU-2 is OH-terminated and the average molecular weight of TPU-2 is less than 50,000.

28. The process of claim 24, wherein the reaction in (a) is carried out at a temperature in a range of from 200 C. to 360 C.

29. The process of claim 24, wherein the reaction in (b) is carried out at a temperature in a range of from 170 C. to 260 C.

30. The process of claim 24, wherein the reaction in (a) and the reaction in (b) are carried out continuously in an extruder.

31. The process of claim 24, wherein a catalyst that accelerates cleavage of TPU-1 is added to the reaction in (a).

32. The process of claim 31, wherein the catalyst is selected from the group consisting of metal catalysts based on tin, zinc, titanium, bismuth or iron.

33. The process of claim 25, wherein D1 is selected from the group consisting of 1,2-ethylene glycol, propane-1,3-diol, butane-1,4-diol and hexane-1,6-diol.

34. The process of claim 25, wherein P1 and/or P2 are selected from the group consisting of polyetherols, polyesterols, polycarbonate alcohols and hybrid polyols.

35. The process of claim 24, wherein the diisocyanate is selected from the group consisting of diphenylmethane 2,2-, 2,4- and/or 4,4-diisocyanate tolylene 2,4- and/or 2,6-diisocyanate (TDI), methylene dicyclohexyl 4,4-, 2,4- and/or 2,2-diisocyanate (H12MD1), hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI).

36. The process of claim 24, wherein TPU-1 or the polyurethane mixture comprising TPU-1 derives from a recycling process.

37. The process of claim 36, wherein the recycling process comprises: (i) providing a shaped article that consists substantially of a thermoplastic polyurethane; (ii) comminuting the shaped article; and (iii) agglomerating the comminuted shaped article to afford an intermediate product (TPU-ZP).

38. The process of claim 37, wherein the shaped article is a shoe or a part of a shoe.

39. The process of claim 37, wherein the shaped article comprises a pure or welded expanded thermoplastic polyurethane.

40. The process of claim 37, wherein the shaped article comprises at least 85% by weight of a thermoplastic polyurethane.

41. The process of claim 37, wherein the shaped article comprises at least 95% by weight of a thermoplastic polyurethane.

42. The process of claim 37, wherein, in the agglomeration of (iii), a temperature is below 200 C.

43. The process of claim 38, wherein, for the agglomeration of (iii), said process employs an apparatus comprising a conveying screw having a feed and an annular compression space, wherein the conveying screw passes feed material axially into the compression space.

44. A thermoplastic polyurethane obtained or obtainable by the process of claim 24.

45. A process for producing an extruded, injection molded or pressed article, a foam, a cable sheathing, a hose, a profile, a drive belt, a fiber, a nonwoven, a film, a molding, a sole, a sporting good, a shoe, a plug, a housing, or a damping element, the process comprising obtaining a thermoplastic polyurethane by a process comprising the process of claim 24.

Description

EXAMPLES 1. Inputs/Materials

[0235] Polyol 1 polytetrahydrofuran having an Mw of 1000 g/mol [0236] Polyol 2 polytetrahydrofuran having an Mw of 2000 g/mol [0237] Polyol 3 polyesterdiol based on adipic acid and butane-1,4-diol, a functionality of 2 and an Mw of 2400 g/mol [0238] Isocyanate 1 4,4-MDI [0239] Diol 1 butane-1,4-diol [0240] Antioxidant 1 phenolic antioxidant [0241] Hydrolysis stabilizer 1 polymeric hydrolysis stabilizer based on carbodiimides [0242] TPU 1 thermoplastic polyurethane based on polyol 1 (61.95% by mass), isocyanate 1 (30.98% by mass), diol 1 (5.57% by mass) and antioxidant 1 (1.00% by mass) [0243] TPU 2 thermoplastic polyurethane based on polyol 1 (61.95% by mass), isocyanate 1 (30.98% by mass), diol 1 (5.57% by mass) and antioxidant 1 (1.00% by mass) [0244] TPU 3 thermoplastic polyurethane based on polyol 3 (56.00% by mass), isocyanate 1 (33.60% by mass), diol 1 (9.95% by mass) and hydrolysis stabilizer 1 (0.45% by mass) [0245] TPU 4 thermoplastic polyurethane based on polyol 1 (29.20% by mass), polyol 2 (29.20% by mass), isocyanate 1 (21.70% by mass), diol 1 (3.88% by mass), antioxidant 1 (1.00% by mass) and plasticizers (15% by mass). [0246] TPU 5 thermoplastic polyurethane based on polyol 1 (48.56% by mass), isocyanate 1 (40.30% by mass), diol 1 (10.14% by mass) and antioxidant 1 (1.00% by mass) [0247] TPU 6 thermoplastic polyurethane based on polyol 1 (41.33% by mass), isocyanate 1 (45.47% by mass), diol 1 (12.65% by mass) and antioxidant 1 (0.55% by mass) [0248] TPU 7 thermoplastic polyurethane based on polyol 1 (37.34% by mass), isocyanate 1 (48.28% by mass), diol 1 (14.04% by mass) and antioxidant 1 (0.50% by mass) [0249] TPU-ZP 1 agglomerated intermediate product based on shaped articles made of TPU 1 (100% by mass) [0250] TPU-ZP 2 agglomerated intermediate product based on a mixture of shaped articles made of TPU 1 (67% by mass) and TPU 4 (33% by mass) [0251] TPU-ZP 3 agglomerated intermediate product based on a mixture of shaped articles made of TPU 1 (60% by mass), TPU 4 (30% by mass) and TPU 7 (10% by mass) [0252] TPU-ZP 4 agglomerated intermediate product based on a mixture of molded articles which consist of TPU 1 (42.5% by mass), TPU 4 (20.5% by mass), TPU 5 (8.33% by mass), TPU 6 (2.1% by mass) and TPU 7 (26.6% by mass) [0253] x-Flex Isocyanate concentrate based on an MDI prepolymer in a polyester-based thermoplastic polyurethane having an NCO content of 10% by weight

[0254] 2. General description of the Experiment

[0255] 2.1 Production of the Agglomerated Intermediate Product (TPU-ZP)

[0256] Provided shaped articles made of thermoplastic polyurethane were milled in a Pallmann PS 3 cutting mill and aspirated into a Pallmann PFV 250 Plast-Agglomerator. At processing temperatures of 130-180 C. the thermoplastic polyurethane to be recycled was agglomerated over just a few seconds and homogeneously processed into a pourable granulate.

[0257] In the comparative examples the agglomeration step described hereinabove was replaced by an extrusion step in a 40 mm twin-screw extruder with underwater pelletization at the customary melt temperatures for the employed TPU.

[0258] 2.2 Examples for Continuous Synthesis

[0259] The recycling-TPU is supplied into the first barrel of a Coperion ZSK58 twin-screw extruder with a screw length of 48D. After melting, the chain extender and optionally a catalyst are added in barrel 3. The transurethanization is carried out at barrel temperatures of 250-300 C. before the amounts of the polyol and diisocyanate required for molar mass growth are added to the reaction mixture in barrel 5. The molar mass growth is performed downstream at barrel temperatures of 180-230 C. Following the synthesis and the obtained melt is subjected to underwater or strand pelletization and dried at 80 C.

[0260] 2.3 Modification for Examples with x-Flex Addition:

[0261] Processing was performed analogously to example 2.3. The addition of the x-Flex was carried out in zone screw 1 together with the TPU.

[0262] 2.4 Extrusion Test

[0263] The granulate was subsequently further processed into test specimens by injection molding or into hoses by extrusion. The hoses were extruded to afford hoses having a diameter of 6 mm by extrusion on a 19 mm single-screw extruder (Brabender) having an L/D ratio of 25 and a 3-zone screw. The zone temperatures were between 160 C. and 200 C. Adjustment of hose geometry was effected by varying the takeoff speed. A visual assessment of the hoses in respect of surface quality (spotting) and homogeneity was carried out.

[0264] 3. Examples

[0265] The working examples were calculated via the hard segment region according to the formulae.

[0266] The following example calculation is carried out by way of example for example V2:

[0267] Specifications: Recycling quota =80%, HSC target-TPU: 32.3% (Shore hardness 90A), HSC recycling TPU: 21.0%

HSC.sub.G-c=(HSC.sub.TPU-targetw.sub.TPU-1*HSC.sub.TPU-1)/(1w.sub.TPU-1) Equation (1) [0268] Example calculation: [0269] HSC.sub.G-c=(32.3%0.8*21.0%)/(10.8) [0270] HSC.sub.G-c=77.5%

m.sub.D1=(HSG-c*mG-b)/((MZI/MD1+1)*100), mass of butanediol based on 100 g of G-c: Equation (5) [0271] Example calculation: [0272] m.sub.D1=(77.5%*100 g)/((250 g/mol/90 g/mol+1)*100) [0273] m.sub.D1=20.5 g

[0274] Accordingly the 20 parts of the TPU comprise 4.20 g of butanediol

[0275] The index of the target TPU may be calculated according to (7). The proportions of MDI and polyols must be chosen such that the desired index is achieved.

KZR.sub.TPU-target=1000*n.sub.ZI/(n.sub.D1+n.sub.P1+n.sub.P2+n.sub.rTPU-1) [0276] Example Calculation:

KZR.sub.TPU-target=1000*(12.95 g/250.2 g/mol)/((4.13 g/190.1 g/mol)+(3.41 g/1000 g/mol)+79.5 g/80 000 g/mol)) KZR.sub.TPU-target=1030 [0277] P2=1000 g/mol, TPU-1=80 000 g/mol, D1=90.1 g/mol, ZI=250.2 g/mol

[0278] 3.1 Comparative Example 1 (VB1) [0279] TPU 1 was reused as a recyclate directly in injection molding.

[0280] 3.2 Comparative Example 2 (VB2) [0281] TPU1 was passed as recyclate through ZSK58 (ZSK58 is a corotating twin-screw extruder from Coperion having an internal diameter of 58mm).

[0282] 3.3 Comparative Example 3 (VB3) [0283] TPU 1 was employed as recyclate, MDI was added to the melt (zone 5). The employed amounts are reported in table 1.

[0284] 3.4 Comparative Example 4 (VB4) [0285] TPU 1 was employed as recyclate. x-Flex was added to the melt (zone 1). The employed amounts are reported in table 1.

[0286] 3.5 Comparative Example 5 (VB5) [0287] TPU 1 was employed as recyclate. x-Flex was added to the melt (zone 1). The employed amounts are reported in table 1.

[0288] 3.6 Example 1 (V1) [0289] TPU 1 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0290] 3.7 Example 2 (V2) [0291] TPU 1 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0292] 3.8 Example 3 (V3) [0293] TPU 1 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0294] 3.9 Example 4 (V4) [0295] TPU 1 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0296] 3.10 Example 5 (V5) [0297] TPU 2 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0298] 3.11 Example 6 (V6) [0299] TPU 3 was employed as recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0300] 3.12 Example 7 (V7) [0301] TPU-ZP 1 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0302] 3.13 Example 8 (V8) [0303] TPU-ZP 2 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0304] 3.14 Example 9 (V9) [0305] TPU-ZP 2 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0306] 3.15 Example 10 (V10) [0307] TPU-ZP 3 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0308] 3.16 Example 11 (V11) [0309] TPU-ZP 4 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1.

[0310] 3.17 Example 12 (V12) [0311] TPU-ZP 4 was used as agglomerated recyclate. Diol 1, polyol 1 and isocyanate 1 were added in the reported amounts. The employed amounts are reported in table 1 a and b.

TABLE-US-00001 TABLE 1a Input materials/ proportions VB 1 VB 2 VB3 VB4 VB5 V1 V2 V3 V4 V5 TPU 1 100 100 97.8 98.5 97.75 79.50 79.51 69.49 79.50 TPU 2 64.88 TPU 3 TPU-ZP1 TPU-ZP2 TPU-ZP3 TPU-ZP4 x-Flex 1.5 2.25 Diol 1 1.5 2.25 1.11 4.13 0.67 1.11 1.04 Polyol 1 12.53 3.41 21.82 12.53 24.81 Isocyanate 1 2.2 6.86 12.95 8.03 6.86 9.27

TABLE-US-00002 TABLE 1b Input materials/ V7 V8 V9 V10 V11 V12 proportions V6 (25/18) (25/20) (25/16) (25/22) (25/14) (25/15) TPU 1 TPU 2 TPU 3 69.83 TPU-ZP1 80 TPU-ZP2 70 70 TPU-ZP3 80 TPU-ZP4 80 50 x-Flex Diol 1 1.02 1.12 0.17 6.67 3.65 3.79 1.58 Polyol 1 20.85 12.62 23.49 3.58 4.97 4.54 35.21 Isocyanate 1 8.30 6.26 6.34 19.67 11.38 11.67 13.20

[0312] 4. Properties of Obtained Agglomerated Intermediate Products

TABLE-US-00003 Tear propagation Elongation strength Abrasion Tensile at break (with cut-in) determination Shore A strength [%] [kN/m] [mm.sup.3] VB2 85 19 580 41 130 ZP1 76 46 710 55 40 ZP2 71 38 780 50 36 ZP3 76 40 720 43 38 ZP4 88 41 510 69 73

[0313] In contrast to the comparative example the inventive intermediate products show good mechanical properties and less cleavage of the polymer chains.

[0314] 5. Properties of Obtained Thermoplastic Polyurethanes

[0315] The obtained thermoplastic polyurethanes were investigated in respect of their mechanical properties. The results are shown in table 2.

TABLE-US-00004 TABLE 2 Tear propagation MFR Elongation strength Abrasion (190 C., Density Tensile at break (with cut-in) determination 21.6 kg) [g/cm.sup.3] Shore A strength [%] [kN/m] [mm.sup.3] VB1 >250 1.104 76 26 830 47 99 VB2 >250 1.103 75 20 840 35 134 VB3 15 1.106 78 41 460 22 48 VB4 46 1.104 77 32 770 50 64 VB5 8.5 1.103 76 43 680 44 47 V1 77 1.102 77 31 850 49 56 V2 5 1.129 89 50 460 58 37 V3 65 1.096 71 36 770 50 47 V4 158 1.103 77 32 820 46 75 V5 n.d. 1.137 93 42 420 78 43 V6 n.d. 1.168 87 39 550 65 38 V7 n.d. 1.117 84 53 510 51 35 V8 47 1.085 65 32 880 44 41 V9 13 1.14 94 45 600 100 39 V10 4.4 1.124 89 45 480 69 34 V11 14 1.126 86 45 600 82 36 V12 73 1.097 75 24 860 47 63

[0316] In contrast to the comparative examples the inventive examples make it possible to specifically adjust Shore hardnesses via the hard segment content and achieve good mechanical properties independently of the input material. The melt viscosities, expressed by the MFR are adjustable through adjustment of the index, the ratio of OH groups to NCO groups.

[0317] 6. Methods of Measurement

TABLE-US-00005 MFR (dried 2 h/110 C.) DIN EN ISO 1134 Density DIN EN ISO 1183-1A Shore A DIN ISO 7619-1 Shore D DIN ISO 7619-1 Tensile strength DIN 53504-S2 Elongation at break DIN 53504-S2 Tear propagation strength (with cut-in) DIN ISO 34-1, B (b] Abrasion determination DIN ISO 4649

Cited Literature

[0318] Kunststoff-Handbuch, volume 7, Polyurethane, 3rd Edition, 1993, edited by G. Oertel, Carl Hanser Verlag, Munich. DE 43 16 389 A1