NEW FLEXIBLE POLYURETHANE FOAMS

Abstract

The present invention relates to a process for producing a flexible polyurethane foam thermally recyclable by fusion, and to hybrid materials made of flexible polyurethane foam and compact thermoplastic elastomer and/or expanded thermoplastic polyurethane.

Claims

1-17. (canceled)

18. A process for producing a thermally recyclable flexible polyurethane foam having a free density between 30 and 150 g/L, the process comprising reacting a mixture comprising a. an isocyanate component having a functionality between 1.9 and 2.2; b. a polyol component having a functionality between 1.7 and 2.2; c. a blowing agent; and d. a catalyst, wherein the polyol component (b) comprises a chain extender.

19. The process of claim 18, wherein the polyol component (b) is a polyester- or polyetherpolyol having an average molecular weight between 500 g/mol and 12 000 g/mol.

20. The process of claim 18, wherein the thermally recyclable flexible polyurethane foam has a softening point of less than 150 C.

21. A thermally recyclable flexible polyurethane foam obtainable by the process of claim 18.

22. A hybrid material comprising the thermally recyclable flexible polyurethane foam of claim 21 and a compact thermoplastic elastomer.

23. A hybrid material comprising the thermally recyclable flexible polyurethane foam of claim 21 and a compact thermoplastic polyurethane.

24. The hybrid material of claim 22, further comprising an expanded thermoplastic polyurethane.

25. The hybrid material of claim 22, wherein at least 50% by weight of the polyol component (b) used to form the thermally recyclable flexible polyurethane foam and of isocyanate-reactive compounds in the thermoplastic polyurethane and at least 50% by weight of the isocyanate component (a) used to form the thermally recyclable flexible polyurethane foam and of organic isocyanates in the thermoplastic polyurethane are identical.

26. A method of recycling the thermally recyclable flexible polyurethane foam of claim 21, the method comprising performing fusion of the thermally recyclable flexible polyurethane foam.

27. A method of recycling the hybrid material of claim 22, the method comprising performing fusion of the hybrid material.

28. A method of producing an item of apparel, jewelry, a jewelry part, an item of sports equipment, a damping material, foam particles, a cleaning article for mobile driving or flying devices, a medical article, a furniture part, a cushion, a cushion part, a mattress, a mattress part, a driving or flying device accessory, a component that absorbs structure-borne and airborne sound, a design element for electrical components and seals, or an article for the agricultural industry and hydroculture substrates, the method comprising obtaining the thermally recyclable flexible polyurethane foam of claim 21.

29. A method of producing footwear, the method comprising obtaining the thermally recyclable flexible polyurethane foam of claim 21.

30. A cushioning element comprising the thermally recyclable flexible polyurethane foam of claim 21 in a heel region, a forefoot region or in a footwear tongue.

31. An insole for footwear, comprising the thermally recyclable flexible polyurethane foam of claim 21.

32. An item of footwear comprising the thermally recyclable flexible polyurethane foam of claim 21 as cushioning in a heel region, forefoot region or in a footwear tongue or as insole.

33. An item of footwear comprising the thermally recyclable flexible polyurethane foam of claim 21 as cushioning in a heel region, forefoot region or in a footwear tongue or as insole and a midsole comprising expanded thermoplastic polyurethane and/or a treadsole, an upper material and/or further footwear part comprising thermoplastic polyurethane.

Description

EXAMPLES

[0196] 1. Feedstocks

TABLE-US-00001 Nominal functionality Polyol 1: Polyesterdiol having a hydroxyl number of 56 mg KOH/g formed from 2 adipic acid, ethylene glycol and butane-1,4-diol Polyol 2: A propylene glycol-started polyoxypropylene polyoxyethylene having a 2 polyoxyethylene content of 18% by weight based on the alkylene oxide content, a hydroxyl number of 29 mg KOH/g and predominantly primary hydroxyl groups. Polyol 3: Polyesterdiol having a hydroxyl number of 38 mg KOH/g formed from 2 adipic acid, butane-1,4-diol and propane-1,2-diol Polyol 4: A 3-(dimethylamino)propylamine-started polyoxypropylene having a 2 polyoxypropylene content of 77% by weight and a hydroxyl number of 250 mg KOH/g Polyol 5: A propylene glycol-started polyoxypropylene having a 2 polyoxypropylene content of 98% by weight and a hydroxyl number of 28 mg KOH/g Polyol 6: A diethylene glycol-started polyoxypropylene-polyoxyethylene having 2 a polyoxyethylene content of 74% by weight based on the alkylene oxide content, a hydroxyl number of 51 mg KOH/g and predominantly primary hydroxyl groups. BA: Water as blowing agent CE 1: Butane-1,4-diol as chain extender from BASF SE 2 CE 2: Ethylene glycol from BASF SE 2 Cat 1: Lupragen N203 amine catalyst from BASF SE Cat 2: KX 611 amine catalyst from BASF Polyurethanes GmbH Cat 3: Lupragen N201 amine catalyst from BASF SE Stab 1: Dabco DC 193 silicone-based stabilizer from Air Products GmbH Iso 1: 55 parts by weight of 4,4-MDI, 1 part by weight of 2,4-MDI, 6 parts by 2 weight of carbodiimide-modified 4,4-MDI and 37 parts by weight of a polyesterdiol having a hydroxyl number of 56 mg KOH/g, formed from adipic acid, ethylene glycol and butane-1,4-diol, were converted to the isocyanate prepolymer. The NCO content was 19%. Iso 2: 85.7 parts by weight of 4,4-MDI, 1.2 parts by weight of 2,4-MDI, 4.9 2 parts by weight of a propylene glycol-started polyoxypropylene having a polyoxypropylene content of 83% by weight and a hydroxyl number of 248 mg KOH/g, and 8.2 parts by weight of dipropylene glycol were converted to the isocyanate prepolymer. The NCO content was 23%. Iso 3: Mixture of 90 parts Iso1 and 10 parts Iso 2. The 2 NCO content was 19.2%. Iso 4: A mixture comprising 49 parts by weight of 4,4-MDI, 48.6 parts by 2 weight of 2,4-MDI and 2.4 parts by weight of 2,2-MDI. The NCO content was 33.5%. System Elastoflex W 5165/142 - commercially available seat foam system 1 (V1): for the motor vehicle and furniture sector based on different glycerol- started polyoxypropylene-polyoxyethylenes having a functionality of 3, a trifunctional chain extender, and an isocyanate component having a proportion of polymeric MDI of 40 parts.

[0197] 2. Production of the Foam Test Specimens

[0198] According to the tables which follow, the feedstocks for the polyol component were mixed with a Vollrath stirrer at 1800 revolutions per minute for 10 min. The isocyanate component was processed at 30 C. On account of viscosity, polyetherpolyols were processed at 25 C. and polyester components at 45 C. Polyol component and polyisocyanate component were then mixed with a Vollrath stirrer at 1800 revolutions per minute for 10 seconds and introduced into a mold. All amounts in the tables which follow for the starting substances are parts by weight (% by weight).

[0199] In addition, a standard, commercially available flexible foam system was included as reference system. A conventional flexible foam system typically consists of a polyol component with feedstocks (polyols and chain extenders/crosslinkers) with functionalities >2. The isocyanate component, often a prepolymer, typically comprises a proportion of polymeric MDI (pMDI), and polyols and chain extenders/crosslinkers having functionalities of 3 or greater. A commercially available seat foam system based on polyhydric polyetherpolyols and pMDI for the vehicle and furniture sector was chosen here as reference system, obtainable as Elastoflex W 5165/142 from BASF SE.

[0200] The flexible foam test specimens obtained were conditioned under standard climatic conditions for 2 days prior to mechanical characterization. Test specimens were cut or die-cut out of these samples, and tear propagation resistance was determined to DIN ISO 34-1A, as were tensile strength and elongation at break to DIN 53543. Abrasion at 10 N was determined to DIN ISO 4649, and the density of foams by Method A of DIN EN ISO 1183-1.

[0201] The melting point was determined with the aid of a heated press at a defined contact pressure over a defined time [sec]. For this purpose, foam cubes with an edge length of 5 cm were prepared. For this purpose, the desired temperatures were established in the upper and lower plates of the heated press and the system was equilibrated for about half an hour. The foam cube was positioned between the upper and lower plates of the heating press, at first without deforming the test specimen. The plates of the heated press were then brought together with the desired contact pressure, determining the time by means of a stopwatch. After the dwell time had expired, the upper and lower plates of the heated press were moved apart again, and the test specimen was removed and assessed.

[0202] The compositions and the results of the measurements are given in tables 1-3.

TABLE-US-00002 TABLE 1 Composition of the formulations (polyester/polyether-based). V1 System 1 B1 B2 B3 B4 B5 Polyol 1 85.00 85.00 42.00 85.00 59.50 Polyol 2 4.50 4.50 4.50 4.50 30.00 Polyol 3 43.00 CE1 3.00 3.00 3.00 3.00 3.00 CE2 3.38 3.38 3.38 3.38 3.38 Cat 1 2.10 2.10 2.10 2.10 Cat 2 2.00 Stab 1 0.08 0.08 0.08 0.08 0.08 BA 2.50 2.50 2.50 2.50 2.50 Iso 1 X X X X Iso 3 X Index 80 95 95 80 80 80 Free density 50 83 85 63 60 75 [g/L] Melting point No melting n.d. n.d. 140 C. at n.d. n.d. [ C.] at contact point, 50 kN for pressure [kN] for carbonized 180 sec time [sec] V: comparative example B: inventive example n.d.: not determined

TABLE-US-00003 TABLE 2 Index variations (polyester/polyether-based). B6 B7 B8 Polyol 1 85.00 85.00 85.00 Polyol 2 4.50 4.50 4.50 CE1 3.00 3.00 3.00 CE2 3.38 3.38 3.38 Cat 1 2.10 2.10 2.10 Stab 1 0.08 0.08 0.08 BA 2.50 2.50 2.50 Iso 1 X X X Index 60 80 120 Free density [g/L] 80 64 81 Melting point [ C.] at 140 C. at 140 C. at 140 C. at contact pressure [kN] 25 kN for 50 kN for 50 kN for for time [sec] 60 sec 180 sec 180 sec

B: Inventive Example

[0203]

TABLE-US-00004 TABLE 3 Composition of the formulations and index variations. (polyetherol-based) B9 B10 B11 B12 B13 B14 Polyol 2 97.00 97.00 97.00 97.00 97.00 97.00 Cat 3 0.80 0.80 0.80 0.80 0.80 0.80 BA 3.00 3.00 3.00 3.00 3.00 3.00 Iso 4 X X X X X X Index 70 80 90 95 100 105 Free density [g/L] 37 35 35 36 37 38.1 Melting point [ C.] 140 C. at 140 C. at 140 C. at 140 C. at 140 C. at 140 C. at at contact pressure 25 kN for 25 kN for 25 kN for 25 kN for 25 kN for 50 kN for 25 kN for 60 sec. 60 sec 60 sec 60 sec 60 sec 60 sec 180 sec B15 B16 B17 B18 Polyol 2 87.00 92.00 92.00 87.00 Polyol 4 10.00 Polyol 5 5.00 Polyol 6 5.00 10.00 Cat 3 0.60 0.80 0.80 0.80 BA 3.00 3.00 3.00 3.00 Iso 4 X X X X Index 95 95 95 95 Free density [g/L] Melting point [ C.] 140 C. at 140 C. at 140 C. at 140 C. at at contact pressure 25 kN for 25 kN for 25 kN for 25 kN for 25 kN for 60 sec. 60 sec 60 sec 60 sec 60 sec V: comparative example B: inventive example

[0204] 3. Compaction of the Foam Test Specimens

[0205] The foam test specimens produced as described above were compacted with the aid of a heated press. For this purpose, a foam body of dimensions 5105 cm was placed between the Teflon-coated metal plates of the press that were at 180 C., and the metal plates were moved together until a pressure of 25-30 kN had been attained. After about 5-7 minutes, the pressure was constant, and so the metal plates were moved apart and the compacted test specimen was removed.

[0206] The compositions and the results of the measurements are given in table 4.

TABLE-US-00005 TABLE 4 Mechanical data for the compaction of the foam. V1 System 1 B3 B4 B12 Shore hardness [A] 55 78 80 81 Tensile strength [MPa] 3 7 5 6 Elongation at break [%] 80 370 210 250 Tear propagation resistance 5 36 39 n.d. [kN/m] Density [g/cm.sup.3] 0.9 1.1 1.1 1.1 V: comparative example B: inventive example n.d.: not determined

[0207] The results show that flexible foams of linear construction show better mechanical properties after compaction than the conventional flexible foam V1. Thus, the foams of the invention can subsequently be used to produce compact or foamed bodies with a (partial) compact layer with advantageous mechanical properties.

[0208] 4. Preparation of the Thermoplastic Polyurethane

[0209] 4.aPreparation of Thermoplastic Polyurethane (Thermoplastic Polyurethane 1)

[0210] 371.4 g of Polyol 4 and 140.4 g of CE 1 were weighed out in a 2 L tinplate bucket and heated up to 80 C. Subsequently, while stirring at 220 rpm, 10 g of AO and 0.5 g of GL were added. After a stirring step for 2 min for homogenization, 482.8 g of Iso 4 were added to the solution and the mixture was stirred (45 s) until the solution had reached a temperature of 110 C. The reaction mixture was then poured into a flat dish and kept at 125 C. on a hot plate for 10 min. Thereafter, the slab formed was subjected to heat treatment in a heated cabinet at 100 C. for 24 h.

[0211] 4.aPreparation of Thermoplastic Polyurethane (Thermoplastic Polyurethane 2)

[0212] 560.1 g of Polyol 4 and 76.6 g of CE 1 were weighed out in a 2 L tinplate bucket and heated up to 80 C. Subsequently, while stirring at 220 rpm, 10 g of AO and 0.5 g of GL were added. After a stirring step for 2 min for homogenization, 352.8 g of Iso 4 were added to the solution and the mixture was stirred (45 s) until the solution had reached a temperature of 110 C. The reaction mixture was then poured into a flat dish and kept at 125 C. on a hot plate for 10 min. Thereafter, the slab formed was subjected to heat treatment in a heated cabinet at 100 C. for 24 h.

[0213] 5. Recycling of the foam test specimens by coextrusion with thermoplastic polyurethane The foam test specimens were sawn into small cubes and compressed at about 50 kN with a heated press at 160 C. for one minute. The compacts obtained were then ground with a 5 mm sieve and the foam pellets were then dried in a heated cabinet at 110 C. for 3 hours.

[0214] The above-described thermoplastic polyurethane samples were comminuted in a mill to give pourable pellets, dried again in a heating cabinet at 110 C. for 3 hours and filled into aluminum-coated PE bags for further use. In the next step, the foam pellets were mixed in different proportions with a mixture of thermoplastic polyurethane 1 and thermoplastic polyurethane 2 in a ratio of 1:1. The mixture of thermoplastically recyclable foam and the thermoplastic polyurethane was extruded in an APV twin-screw extruder that gives a strand diameter of about 2 mm. The following parameters were set:

TABLE-US-00006 Extruder: Corotating APV MP19 twin-screw extruder Screw diameter 19 mm Temperature profile: HZ1 (intake) about 225 C. HZ2 about 225 C. HZ3 about 220 C. HZ4 about 215 C. HZ5 (nozzle) about 215 C. Screw speed: 100 rpm Pressure: about 10 to 30 bar Extrudate cooling: water bath (10 C.)

[0215] The strands were pelletized, dried and processed by means of injection molding to give injection-molded sheets of thickness 2 and 6 mm, on which the mechanical properties according to tables 5 and 6 were determined.

TABLE-US-00007 TABLE 5 Mechanical characterization of the injection-molded sheets from the coextrusion of thermoplastic polyurethane 1 and thermoplastic polyurethane 2 in a ratio of 1:1 with flexible foam B2. V2 E1 E2 E3 E4 Foam from B2 [% by wt.] 0 5 10 20 25 Shore hardness [A] 94 94 93 92 91 Shore hardness [D] 52 46 44 42 40 Tensile strength [MPa] 43 33 25 15 15 Elongation at break [%] 510 530 530 440 460 Tear propagation resistance 112 102 84 57 53 [kN/m] Abrasion [mm.sup.3] 52 106 168 225 249 Density [g/cm.sup.3] 1.1 1.1 1.2 1.2 1.2 Appearance of the test sheet transparent transparent, translucent, opaque, opaque, yellowish yellowish yellowish yellowish V: comparative example E: inventive example

TABLE-US-00008 TABLE 6 Mechanical characterization of the injection-molded sheets from the coextrusion of thermoplastic polyurethane 1 and thermoplastic polyurethane 2 in a ratio of 1:1 with flexible foam B12. E5) E6 E7 Foam from B12 [% by wt.] 5 10 20 Shore hardness [A] 94 93 92 Shore hardness [D] 48 43 40 Tensile strength [MPa] 48 44 36 Elongation at break [%] 530 560 580 Tear propagation resistance 108 98 78 [kN/m] Abrasion [mm.sup.3] 53 60 84 Density [g/cm.sup.3] 1.1 1.1 1.1 Appearance of the test sheet translucent, opaque, opaque, yellowish yellowish yellowish V: comparative example E: inventive example

TABLE-US-00009 TABLE 7 Mechanical characterization of the injection-molded sheets from the coextrusion of thermoplastic polyurethane 1 and thermoplastic polyurethane 2 in a ratio of 1:1 with System 1 (V1). V3 V4 Foam from V1 [% by wt.] 5 20 Shore hardness [A] 93 91 Shore hardness [D] 43 38 Tensile strength [MPa] 32 16 Elongation at break [%] 520 410 Tear propagation resistance 83 58 [kN/m] Abrasion [mm.sup.3] 105 162 Density [g/cm.sup.3] 1.1 1.1 Appearance of the test sheet yellowish, yellowish, opaque, rough opaque, rough surface surface V: comparative example

[0216] The results show that the inventive flexible polyurethane foams have good thermal recyclability with a proportion of added thermoplastic polyurethane. The sheets obtained are surprisingly homogeneous and have a smooth surface. By contrast, a conventional crosslinked flexible foam, such as V1, can be incorporated only in small amounts (i.e. max. 20%); in addition, the sheets resulting therefrom were inhomogeneous and rough even at low concentrations of V1.

LITERATURE CITED

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