Novel particle foams

Abstract

A process can be used for producing a thermoplastic polyurethane, where the process at least involves converting at least one isocyanate composition and a polyol composition, to obtain a prepolymer having isocyanate groups, and reacting the resulting prepolymer with at least one chain extender. The at least one isocyanate composition contains an isocyanate selected from naphthylene 1,5-diisocyanate (NDI), diphenylmethane 4,4′-diisocyanate (MDI), p-phenyl diisocyanate (PPDI), o-tolidine diisocyanate (TODI), ethylene diphenyl diisocyanate (EDI), or mixtures thereof. The polyol composition contains a polytetrahydrofuran or a derivative thereof. A thermoplastic polyurethane obtained or obtainable by such a process is useful, and a foamed pellet material can be produced containing such a thermoplastic polyurethane. The foamed pellet material of the invention can be used for production of a molded article.

Claims

1-16. (canceled)

17. A foamed pellet material, comprising a thermoplastic polyurethane obtainable or obtained by a process comprising at least: (i) converting at least one isocyanate composition (Z1), comprising an isocyanate (I1) selected from the group consisting of naphthylene 1,5-diisocyanate (NDI), diphenylmethane 4,4′-diisocyanate (MDI), p-phenyl diisocyanate (PPDI), o-tolidine diisocyanate (TODI), ethylene diphenyl diisocyanate (EDI), and a mixture thereof; and a polyol composition (ZP) comprising a polytetrahydrofuran or a derivative thereof; to obtain a prepolymer having isocyanate groups, and (ii) reacting the prepolymer obtained in (i) with at least one chain extender (KV).

18. The foamed pellet material according to claim 17, wherein the derivative of polytetrahydrofuran is a poly-ε-caprolactonepolyol.

19. The foamed pellet material according to claim 17, wherein at least one further component is used in the reaction in (ii), selected from the group consisting of polyols, chain extenders, catalysts, cell nucleators, other auxiliaries, and additives.

20. The foamed pellet material according to claim 18, wherein the poly-ε-caprolactonepolyol is obtainable or obtained by reaction of ε-caprolactone and a starter molecule selected from the group consisting of α-hydro-ω-hydroxypoly(oxytetramethylene)diols.

21. The foamed pellet material according to claim 17, wherein the at least one isocyanate composition (ZI) comprises naphthylene 1,5-diisocyanate (NDI) in an amount in the range from 90% to 100% by weight, based on the at least one isocyanate composition (ZI).

22. The foamed pellet material according to claim 17, wherein the at least one chain extender (KV) is selected from the group consisting of diols having a molecular weight in the range from 50 to 500 g/mol and diamines having a molecular weight in the range from 50 to 500 g/mol.

23. The foamed pellet material according to claim 17, wherein the at least one chain extender (KV) is selected from the group consisting of MEG, butane-1,4-diol, propane-1,3-diol, hexane-1,6-diol, 2-ethylhexane-1,3-diol, and 2-butyl-2-ethylpropanediol.

24. The foamed pellet material according to claim 17, wherein an average diameter of a bead of the foamed pellet material is in the range from 0.5 to 20 mm.

25. A molded article, obtainable from the foamed pellet material according to claim 17.

26. A method, comprising: molding the foamed pellet material according to claim 17, to produce a molded article.

27. The method according to claim 26, wherein the molded article is produced by fusing or bonding of heads of the foamed pellet material to one another.

28. The method according to claim 26, wherein the molded article is a footwear sole, part of a footwear sole, a mattress, underlay, grip, protective film, a component in an automobile interior or exterior, a gymnastics mat, a body protector, a trim element in automobile construction, a sound insulator, a vibration damper, a cushion, a bicycle seat, a toy, a tire, a part of a tire, a covering for a track and field surface, a sports hall, a pathway, a damping layer or a damping core in a sandwich element, and a packaging.

29. A molded article, comprising the foamed pellet material according to claim 17, wherein the molded article is selected from the group consisting of a ball, sports equipment, floor covering, wall paneling, a sports surface, a track and field surface, a sports hall, a children's playground, and a pathway.

30. A hybrid material, comprising a matrix composed of a polymer (PM) and the foamed pellet material according to claim 17.

Description

EXAMPLES

[0315] 1. Production Examples for Thermoplastic Polyurethanes

[0316] 1.1 Experiment 1 (TPU 1)

[0317] 1000 parts by weight of polyol (PCL-capped PTHF (PCL500-PTHF1000-PCL500), PTHF2000 4:1) is heated to a temperature between 130-160° C., and 200 parts by weight of NDI is added in solid form and reacted. After a reaction time of 30-50 minutes within a temperature range of 150-90° C., a prepolymer having an NCO content of 3.2% and a viscosity of 2500 mPas is obtained at 90° C.

[0318] Within 2 h after production, 100 parts by weight of the prepolymer thus obtained was mixed homogeneously with 3.4 parts by weight of butane-1,4-diol at a temperature of 90° C. and introduced into a mold having, a mold temperature between 80-100° C.

[0319] After a curing time of 20-30 minutes, the material was subjected to heat treatment at a temperature of 110° C. for 14 h can the material obtained be processed further by injection molding.

[0320] The resultant TPU 1 was pelletized by means of a mill and transformed to lenticular granules via underwater pelletization by extrusion with a ZSK40 twin-screw extruder having a maximum zone temperature of 220° C. and a perforated plate temperature of 230° C. The TPU was then dried at 80° C. for 1.5 h.

[0321] 1.2 Experiment 2 (TPU 2)

[0322] 1000 parts by weight of polyol (PCL-capped PTHF, PTHF2000 4:1) is heated to a temperature between 130-160° C., and 200 parts by weight of NDI is added in solid form and reacted. After a reaction time of 30-50 minutes within a temperature range of 150-90° C., a prepolymer having an NCO content of 2.87% and a viscosity of 2960 mPas is obtained at 90° C.

[0323] Within 4 h after production, 100 parts by weight of the prepolymer thus obtained was mixed homogeneously with 2.73 parts by weight of a mixture consisting of 100 parts propane-1,3-diol and 5 parts of an amine catalyst mixture (65% N-methyl-N-dimethylaminoethylpiperazine and 35% pentamethyldiethylenetriamine) at a temperature of 90° C. and introduced into a mold having a mold temperature between 80-100° C.

[0324] After a curing time of 20-30 minutes, the material was subjected to heat treatment at a temperature of 110° C. for 14 h can the material obtained be processed further by injection molding.

[0325] In the subsequent reprocessing to give lenticular granules, talc was added at a concentration of 0.05%.

[0326] 1.3 Determination Method for the NCO Content:

[0327] Solutions:

[0328] Di-n-hexylamine solution: 166.8 g of di-n-hexylamine is made up to 1.0 L with xylene (in a 1 L standard flask) and homogenized.

[0329] 1% bromophenol blue solution: 0.5 g of bromophenol blue is dissolved in 49.5 g of ethanol and transferred into a pipette bottle.

[0330] Procedure:

[0331] 10 mL of the amine solution is dispensed into an Erlenmeyer flask. Subsequently, 20 mL of chlorobenzene is added. For an expected isocyanate content of 4%, 2 g-2.5 g of prepolymer is weighed in accurately to 0.1 mg (the weights for other isocyanate concentrations have to be adjusted correspondingly). After complete dissolution (visual check), 50 mL of methanol is added. After addition of 3 drops of bromophenol blue solution, the unconsumed amine is then back-titrated with HCl (c=1.0 mol/L) until the color changes from blue to yellow.

[0332] The blank samples, i.e. samples containing no prepolymer, are treated in the same way—except without weighing out the sample,

Calculation: NCO free=(((V.sub.BLK−V.sub.sample)*M*c*t)/m)*100% [0333] with V.sub.BLK=consumption of HCl (1.0 mol/L) for blank in L [0334] V.sub.sample=consumption of HCl (1.0 mol/L) for sample in L [0335] M=molar mass of NCO 42.02 g/mol [0336] C=molar concentration of HCl 1.9 mol/L [0337] t=HCl titer (1.0 mol/L) [0338] m=sample weight of prepolymer in g

[0339] 1.4 Example 3 (TPU 3)—Reactive Extruder

[0340] a. Example of Continuous Synthesis

[0341] NDI and any solid additives are fed into the first barrel of a ZSK32 MC, twin-screw extruder from Coperion with a processing length of 56D. The polyols that have been heated to 160° C., and also catalyst and any liquid additives, are fed into the molten NDI in the second barrel. After mixing and (partial) reaction of the components, the chain extender is added downstream, to the fifth zone. At barrel temperatures of 190-220° C., the reaction components are converted up to a conversion level of >95%. After the synthesis, the resulting polymer melt is subjected to underwater pelietization, and the resulting pellets are dried.

[0342] As a variation of the process specified above, all liquid components can also be added to zone 2.

TABLE-US-00001 Sample A Sample B KZ 990 KZ 960 Dosage rate g/min PolyTHF 2000, 54.1 54.1 OHN = 56.0 mgKOH/g CAPA 7201A, 216.5 216.5 OHN = 56.4 mgKOH/g Desmodur 15 53.1 51.5 Propane-1,3-diol 9.1 9.1 TBOT 75 ppm 75 ppm MFR (200° C./2.16 kg) MFR (190° C./21.6 kg) MFR1 15 h/80° C. MFR 15 h/80° C. no heat + 1 MFR1 + Sample KZ treatment 15 h/80° C. 2 h/110° C. fresh 15 h/80° C. 2 h/110° C. A 990 6 4.9 1.9 130 72 58 B 960 28 4.7 5.3 >250 171 167

[0343] 2. Test Methods:

[0344] Test methods/indices used for characterization of the pellet materials used, and of the resulting foam beads and moldings, including the following:

[0345] a. Determination of Melting Point by DSC

[0346] Procedure to ISO 11357-3 (German version of Apr. 1, 2013) with DSC Q100 from TA Instruments. To determine the melting point of the thermoplastic elastomer used or of other thermoplastic elastomers of the invention, 3-5 mg in pellet form is heated up at a heating rate of 20° C./min in a 1st run between 20° C. and 200° C., then cooled down to 20° C. at 10° C./min, followed by a further heating cycle (2nd run) at a heating rate of 10° C./min. The melting point reported was the peak maximum temperature in the 2nd run.

[0347] b. Bulk Density

[0348] The determination was in accordance with DIN EN ISO 60: 2.000-1. The foam beads are introduced here with the aid of a funnel having fixed geometry (completely filled with bulk material) into a measuring cylinder of known volume, the excess bulk material is leveled off from the measuring cylinder with a straight-edged bar, and the contents of the measuring cylinder are ascertained by weighing.

[0349] The funnel used is 40 cm high, and had an opening angle of 35° and an outlet of diameter 50 mm. The measuring cylinder used had an internal diameter of 188 mm and a volume of 10 L.

[0350] The bulk density (SD) was calculated from the mass of the bed of material [kg]/0.01 [m.sup.3].

[0351] The bulk density reported was the average from 3 measurements in kg/m.sup.3.

[0352] Average Cell Density

[0353] The foam structure was assessed by visual image analysis with a PORE!SCAN Advanced Plus from Goldlücke Ingenieurleistungen. For this purpose, 10 foam beads in each case are halved and a cross-sectional area of each is measured. In the case of nonspherical, for example elongated, cylindrical or ellipsoidal, foam beads, the division is in the direction of the longest dimension.

[0354] The average cell density is the ratio of the number of cells in the cross-sectional area to the cross-sectional area, and is reported in 1/mm.sup.2.

[0355] The value is assigned to a classification:

TABLE-US-00002 Classification Average cell density [1/mm.sup.2] F fine cells >100 N normal cells 10-100 G coarse cells  <10

[0356] d. Densification Level VG

[0357] The densification level VG is the ratio of molding density (FT density) to bulk density (SD), VG=FT density [kg/m.sup.3]/SD [kg/m.sup.3].

[0358] e. Further Test Methods:

[0359] Further test methods utilized for material characterization may include the following: DMA, TMA, NMR, FT-IR, GPC

TABLE-US-00003 Apparent density DIN EN ISO 845: 2009 October Tear propagation resistance DIN LN ISO 8067: 2009 June Dimensional stability ISO 2796: 1986 August Tensile test ASTM D5035: 2011 Resilience DIN 53512: 2000 April

[0360] 3. Production of Foam Beads by Impregnation in an Autoclave

[0361] 3.1 Starting Materials

[0362] For the E-TPU examples 1 to 7 (and the comparative examples), the following TPU materials were used:

TABLE-US-00004 Density (20 kg/m.sup.3) TPU 1 in the form of lenticular pellets 1150 kg/m.sup.3 TPU 2 in the form of lenticular pellets 1150 kg/m.sup.3

[0363] The experiments were conducted with a tank fill level of 80% and a phase ratio of 0.38. The phase ratio is defined here as the ratio of the masses of pellets to suspension medium, water in the examples.

[0364] 3.2 General Production Method for Example E-TPU Example 1 to E-TPU Example 7

[0365] 100 parts by weight (corresponding to 27.1% by weight, based on the overall suspension without blowing agent) of the pellets, 262 parts by weight (corresponding to 71.0% by weight, based on the overall suspension without blowing agent) of water, 6.7 parts by weight (corresponding to 1.8% by weight, based on the overall suspension without blowing agent) of calcium carbonate (suspension auxiliary), 0.13 part by weight (corresponding to 0.04% by weight, based on the overall suspension without blowing agent) of a surface-active substance (Lutensol AT 25; suspension auxiliary) and the appropriate amount of butane as blowing agent (based on the amount of pellets used) were heated while stirring.

[0366] Then nitrogen was additionally injected into the liquid phase at 50° C., and the internal pressure was adjusted to a predefined pressure (800 kPa). This is followed by expansion via an expansion device on attainment of the impregnation temperature (IMT) and optionally after observing a hold time (HZ) and at the impregnation pressure (IMP) established at the end. The gas space here is adjusted to a fixed expulsion pressure (AP) and kept constant during the expansion. The expansion jet downstream of the expansion device may optionally be cooled with a particular volume flow rate of water at a specific temperature (water quench).

[0367] The hold time defines the time at which the temperature of the liquid phase is within a temperature range from 5° C. below the impregnation temperature to 2° C. above the impregnation temperature.

[0368] After removal of the suspension medium/suspension auxiliary system (dispersant/surfactant) and drying, the bulk density (SD) of the resulting foam beads is measured.

[0369] The exact production parameters and bulk density of the resulting batches (foam beads) are listed in tables 1a and 1b.

TABLE-US-00005 TABLE 1a Experimental parameters for examples 1 to 7 Blowing Pellet type Bead agent geometry Blowing content IMT Hold time Example Bead mass [mg] agent [% by wt.] [° C.] [min] E-TPU TPU1 butane 24.0 150.0 3 Example 1 UWP 30 E-TPU TPU1 butane 24.0 151.0 4 Example 2 UWP 30 E-TPU TPU2 butane 24.0 115 3 Example 3 UWP 34 E-TPU TPU2 butane 24.0 120 3 Example 4 UWP 34 E-TPU TPU2 butane 24.0 115 22 Example 5 UWP 34 E-TPU TPU2 butane 24.0 116 22 Example 6 UWP 34 E-TPU TPU2 butane 24.0 117 20 Example 7 UWP 34

TABLE-US-00006 TABLE 1b Experimental parameters for examples 1 to 7 Expulsion Bulk density Average cell IMP pressure Water SD density Example [kPa] [kPa] quench [kg/m.sup.3] Classification E-TPU 3130 4000 yes 122 F.sup.1 Example 1 E-TPU 3120 4000 yes 119 F.sup.1 Example 2 E-TPU 2570 4000 no 189 F Example 3 E-TPU 2780 4000 no 152 F Example 4 E-TPU 2380 4000 no 152 F Example 5 E-TPU 2420 4000 no 147 F Example 6 E-TPU 2570 4000 no 150 F Example 7 .sup.1Cell structure of the foamed pellet material contains bubbles and cracks

4. Production of Moldings

[0370] The foam beads (expanded pellets) were subsequently welded in a molding machine from Kurtz Ersa GmbH (Energy Foamer K68) to give square plaques having a side length of 200 mm and a thickness of 10 mm and 20 mm, or in a molding machine from Erlenbach (EHV-C870/670) rectangular plaques having a side length of 300×200 mm and a thickness of 10 mm, by contacting with steam.

[0371] The moldings can be produced by the pressure filling method or by the crack filling method. For the inventive examples, the crack filling method was used (see table 2).

[0372] After the production, the moldings were stored at 60° C. to 70° C. for 4 to 16 h and then the molding density was tested (table 2).

TABLE-US-00007 TABLE 2 Steam pressures and times for welding of the materials from the examples and comparative examples Cross-steam Cross-steam Autoclave Mold- 1 2 steam Total ing mold- E- Time/ Time/ Time/ cooling thick- ing Mold- TPU/ Crack pressure pressure pressure time ness density ing ex. [mm] [s] [bar] [s] [bar] [s] [bar] [s] [mm] [kg/m.sup.3] FT 1 1 10.0 4/4.0 7/4.0 32/4.0 30 10 KV FT 2 3 8.0 4/2.5 7/2.5 32/2.5 96 10 399 FT 3 5 10.0 4/2.5 7/2.5 32/2.5 68 10 373 FT 4 4 8.0 4/2.5 7/7.5 32/2.5 77 10 326 FT 5 7 8.0 4/2.7 7/2.7 32/2.7 73 10 326 FT 6 7 5.0 4/2.5 7/2.5 32/2.5 30 10 296 FT 7 7 14.0 10/0.7  20/2.9  32/2.9 100 10 n.d. FT 8 7 22.0 10/0.7  20/2.9  32/2.9 120 20 429 KV no welding/no FT production possible, n.d. not determined

[0373] The results of the mold tests are listed in table 3.

TABLE-US-00008 TABLE 3 Compressive Compressive Pendulum strength strength rebound Tensile Elongation at (at 10% (at 50% resilience strength break compression) compression) [%] [kPa] [%] [kPa] [kPa] Molding DIN 53512 ASTM D 5035 ISO 844 FT2 79.7 1534 157 99 841 FT3 79.1 1476 165 84 677 FT4 79.1 1486 187 68 503 FT5 78.7 1442 200 63 501 FT6 78.7 1105 165 35 421 FT 8 79.0 n.d. n.d. n.d. n.d. n.d. not determined

[0374] 5. Examples for Production of Hybrid Materials

[0375] 5.1 General Production Procedure for Hybrid Material

[0376] The beads produced above were used to produce moldings by means of a PU system or binder. For this purpose, first of all, the liquid formulations were prepared and these were then mixed vigorously with the beads in a plastic vessel made of polyethylene, before they were discharged into the molds. The mold used was a Teflon-coated wooden mold having internal dimensions of 4.5×4.5×4.5 cm. By means of an inlay of 4.5×4.5×2.5 cm, it was possible to produce either cubes or slabs of thickness 2 cm from the formulations.

[0377] 5.2 Starting Materials

[0378] Beads used: E-TPU1

[0379] 5.3 Foam System and Binder

TABLE-US-00009 A comp. 94 parts Name Parts Wt. [%] Wt. [g] OH/NH H2O [%] PolyTHF 2000 67.000 67.000 670.000 56.0 0.015 Rizinusoel DAB 21.000 21.000 210.000 160.5 0.030 10 Spezial MONOETHYLENE 4.600 4.600 46.000 1,810.0 0.200 GLYCOL TECH. TINUVIN 213 3.000 3.000 30.000 180.0 0.040 TEGOSTAB B8462 2.000 2.000 20.000 115.0 0.200 Mullopol Fin 2.000 2.000 20.000 0.0 50.000 1-Methylimidazole 0.400 0.400 4.000 4.0 0.500 B comp. 100 parts Iso137/28 (NCO [%] 18.00) Name Amount 4,4′ MDI 61.4 Carbodiimide-modified MDI 2 Antioxidant 0.09 Diglycol bis(chloroformate) 0.01 Polyol mixture of 89.05% 36.5 polypropylene glycol Mw2000 and 10.95% tripropylene glycol

[0380] 5.4 Gel system

TABLE-US-00010 A comp. 94 parts Name Parts Wt. [% Wt. [g] OH/NH H2O [%] PolyTHF 2000 67.000 67.000 670.000 56.0 0.015 Rizinusoel DAB 10 Spezial 21.000 21.000 210.000 160.5 0.030 MONOETHYLENE GLYCOL TECH. 4.600 4.600 46.000 1,810.0 0.200 TINUVIN 213 3.000 3.000 30.000 180.0 0.040 TEGOSTAB B8462 2.000 2.000 20.000 115.0 0.200 Mullopol Fin 2.000 2.000 20.000 0.0 50.000 1-Methylimidazole 0.400 0.400 4.000 4.0 0.500 B comp. 100 parts Iso137/28 (NCO [%] 18.00) Name Amount Name Amount 61.4 4,4′ MDI 61.4 2 Carbodiimide-modified MDI 2 0.09 Antioxidant 0.09 0.01 Diglycol bis(chloroformate) 0.01 Polyol mixture of 89.05% polypropylene glycol 36.5 36.5 Mw2000 and 10.95% tripropylene glycol A comp. 100 parts Name % by wt. Propylene glycol-started 97.847 PO-EO ether of functionality 1.76 and Mw 3410 Dipropylene glycol 1.761 monomethyl ether Coscat 83 0.391 B comp. 11 parts Name % by wt. Trimerized hexamethylene 100 diisocyanate

[0381] 5.5 Results

TABLE-US-00011 % by % by % by % by wt. of Component wt. of wt. of wt. of gel density Resilience Experiment beads system water system (kg/m.sup.3) (5) 1 40 60 1 300 77 2 50 50 1 300 77 3 50 50 1 220 75 4 40 60 2 760 71 5 50 50 2 260 74 6 80 20 0 260 73 7 33 67 390 78 8 40 60 360 78

[0382] 6. Production of eTPU/PU Foam Hybrid Sheets

[0383] With the aid of a dosage machine (4K TPY NDF 20-4 low-pressure machine from Elastogran GmbH), component A that had been preheated to 40° C. and component B that had been preheated to 25° C., with the composition listed in table 4, were added at a pressure of 16 bar under time control in accordance with the details from table 4 to the appropriate amount of E-TPU that was in a 27 L plastic beaker.

TABLE-US-00012 TABLE 4 Composition of the A and B component PU foam 1 PU foam 2 PU foam 3 PU foam 4 PTHF Mn 2000 g/mol [% by 98.6 98.6 98.674 96.770 wt.] Deionized water [% by wt.] 1 2 0.663 0.65 Diethanolamine [% by wt.] 0.1 0.1 0.102 0.3 A 33% solution of 0.2 0.2 0.204 1.4 triethylenediamine in monoethylene glycol (Lupragen N 203) [% by wt.] DABCO 1027 [% by wt.] 0.1 0.1 0.102 0.63 Prepolymer based on 40% by 100 100 weight of PTHF2000, 53.98% by weight of MDI (Lupranat ME), 6% by weight of a carbodiimide-modified MDI having an average functionality of 2.2 (Lupranat MM103) and 0.02% by weight of diglycol bis(chloroformate) having a residual NCO content of 18% [% by weight] Tegostab B 8491 0.153 0.150 Bis(2-dimethylaminoethyl) 0.102 0.1 ether Iso 137/53 100 100

[0384] The dosage parameters derive from the fact that a loss of about 10% of the total mass of the foam system remains in the mixing and transferring of E-TPU and foam. This is checked by the weighing of the finished test sheets that had been adjusted to a density of 300 (PU foam 1) or 260 kg/m.sup.3 (PU foam 2).

TABLE-US-00013 TABLE 5 Time-dependent dosages of the dosage machine used (E-TPU 1) Sheet of thickness Sheet of thicknes 20 mm (210 g) 10 mm (105 g) Mass Mass of of Proportion E- PU Dosage E- PU Dosage E- PU of E-TPU TPU foam time TPU foam time Name TPU foam [% by wt.] [g] [g] [s] [g] [g] [s] Hybrid E- PU foam 1 40 84 138 2.61 42 73 1.44 1 TPU 1 Hybrid E- PU foam 1 50 105 115 2.2 53 58 1.15 2 IPU 1 Hybrid E- PU foam 2 40 84 138 2.61 42 73 1.44 3 TPU 1 Hybrid E- PU foam 2 50 105 115 2.2 53 58 1.15 4 TPU 1

[0385] Immediately thereafter, the components and the E-TPU were immediately mixed with the aid of a laboratory stirrer (EWTHV-05 type from Vollrath GmbH) for a maximum of 10 s and then introduced and distributed homogeneously with a wooden spatula into an open aluminum mold having the dimensions of 20×20×1 cm or 20×20×2 cm that had been preheated to 45° C. and painted with silicone (marbo super release s) until the gel time of about 40 s had been attained. The aluminum mold was heated using an SC 100 heating device from Thermo Scientific.

[0386] After the mold has been closed, the system reacts to completion for 30 min. The ventilation of the mold is controlled here by ventilation channels, while the mold temperature is kept constant at 45° C.

[0387] Before the test sheets were tested, they were stored at room temperature for at least 2 days in order to ensure that the PU foam had reacted to completion. Resilience (also referred to as rebound) according to DIN 53512: 2000-04 and the densities according to DIN EN ISO 845: 2009-10 of the resultant 20 mm sheets are listed in table

TABLE-US-00014 TABLE 6 Measured densities and resilience of the hybrid sheets obtained Name Density [kg/m.sup.3] Resilience [%] Hybrid 1 300 77 Hybrid 2 300 77 Hybrid 3 260 71 Hybrid 4 260 74

[0388] By a low level of catalysis, PU foam 3 was processed in the same procedure as foams 1 and 2, and a proportion of 70% bead mass was introduced. PU foam 4, owing to the faster reaction time, was introduced directly into an E-TPU-filled mold and subsequently forms a foam around it. The completely filled mold permits a proportion of about 50% of the bead mass. The faster-reacting system achieves a demolding time of about 5 min. All other processing parameters are maintained.

[0389] The mechanical test data that follow were ascertained on the test sheets of thickness 20 mm.

TABLE-US-00015 TABLE 7 Test results for the hybrid sheets PU foam 3 and 4 Tear Change Change Apparent propagation in in density resistance length height Resilience [kg/m.sup.3] [N/mm] [%] [%] [%] PU foam 4 pure 301 1.7 −1.7 1.9 66 Hybrid 5 PU foam 4 50% eTPU 1 285 3.3 −0.2 6.1 71 PU foam 3 pure 307 2.9 −0.9 −0.2 52 Hybrid 6 PU foam 3 70% eTPU 1 274 3.2 −0.2 6.5 69

LITERATURE CITED

[0390] WO 94/20568 A1

[0391] WO 2007/082838 A1

[0392] WO 2017/030835 A1

[0393] WO 2013/153190 A1

[0394] WO 2010/010010 A1

[0395] “Kunststoffhandbuch”, volume 7, “Polyurethane”, Cad Hanser Verlag, 3rd edition, 1993, chapter 3.1

[0396] Saechtling (ed.), Kunststott-Taschenbuch, 27th edition, Hanser-Verlag Munich 1998, chapters 3.2.1 and 3.2.4

[0397] WO 2014/150122 A1

[0398] WO 2014/150124 A1

[0399] EP 1979401B1

[0400] US 20150337102 A1

[0401] EP 2872309B1

[0402] EP 3053732 A

[0403] WO 2016/146537 A1

[0404] “Kunststoffhandbuch”, volume 7, “Polyurethane” Carl Hanser Verlag, 3rd edition, 1993 chapter 3

[0405] “Integralschaumstoff’, Carl-Hanser-Verlag, Munich, Vienna, 1975, or in Kunststoff-Handbuch, volume 7, Polyurethane, 3rd edition, 1993, chapter 7