Foams based on thermoplastic elastomers

Abstract

The present invention relates to bead foams made of thermoplastic polyurethane and polystyrene produced moldings, to processes for the production of the bead foams and moldings, and also to the use of the moldings for shoe intermediate soles, shoe insoles, shoe combisoles, or cushioning elements for shoes.

Claims

1. A molded body made of bead foam, the bead foam made of a composition (Z) comprising: from 70 to 95% by weight of a thermoplastic polyurethane having a molecular weight Mw of 60,000 to 300,000 g/mol as determined by gel permeation chromatography as component I, and from 5 to 30% by weight of a styrene polymer having a modulus of elasticity in tension of above 2,500 MPa according to DIN EN ISO 527-1/2, June 2012, as component II, wherein the entirety of components I and II provides 100% by weight; the molded body is at least one selected from the group consisting of an intermediate sole for a shoe, an insert for a shoe, and a cushioning element for a shoe and a tensile strength of the molded body is above 600 kPa.

2. The molded body according to claim 1, wherein the composition Z comprises from 80 to 90% by weight of the thermoplastic polyurethane as component I, and from 10 to 20% by weight of the styrene polymer as component II.

3. The molded body according to claim 1, wherein the shoe is at least one selected from the group consisting of an outdoor shoe, a sports shoe, a sandal, a boot and a safety shoe.

4. The molded body according to claim 1, wherein the elongation at break of the molded body is above 100%.

5. The molded body according to claim 1, wherein the compressive stress of the molded body at 10% compression is above 15 kPa.

6. The molded body according to claim 1, wherein the density of the molded body is from 75 to 375 kg/m.sup.3.

7. The molded body according to claim 1, wherein the rebound resilience of the molded body is above 55%.

8. The molded body according to claim 1, wherein the ratio of the density of the molded body to the bulk density of the bead foam is from 1.5 to 2.5.

9. A process for the production of a molded body according to claim 1, comprising introducing the bead foam into a mold, and fusing the bead foam after the introducing.

10. The process according to claim 9, wherein the fusing is achieved in a closed mold.

11. The process according to claim 9, wherein the fusing is achieved by means of at least one selected from the group consisting of steam, hot air, and high-energy radiation.

12. A shoe, comprising a molded body according to claim 1.

13. A molded body comprising a bead foam, the bead foam comprising: from 70 to 95% by weight of a thermoplastic polyurethane having a molecular weight Mw of 60,000 to 300,000 g/mol as determined by gel permeation chromatography as component I, and from 5 to 30% by weight of a styrene polymer having a modulus of elasticity in tension of above 2,500 MPa according to DIN EN ISO 527-1/2, June 2012, as component II, wherein the entirety of components I and II provides 100% by weight; a tensile strength of the molded body is above 600 kPa, and the molded body is a whole or a part of at least one selected from the group consisting of a shoe intermediate sole, a shoe insole, a shoe combisole, a cushioner for a shoe, a bicycle saddle, a bicycle tire, a damping element, a cushioning, a mattress, an underlay, a grip, a protective film, a component in the automobile interior sector, a component in the automobile exterior sector, a ball, a sport equipment, and a floorcovering.

14. The molded body according to claim 13, which is a whole or a part of at least one selected from the group consisting of a shoe intermediate sole, a shoe insole, a shoe combisole, and a cushioner for a shoe, wherein the shoe is at least one selected from the group consisting of an outdoor shoe, a sports shoe, a sandal, a boot, and a safety shoe.

Description

EXAMPLES

(1) The expanded beads made of thermoplastic polyurethane and of the styrene polymer were produced by using a twin-screw extruder with screw diameter 44 mm and length-to-diameter ratio 42 with attached melt pump, a diverter valve with screen changer, a pelletizing die and an underwater pelletization system. In accordance with processing guidelines, the thermoplastic polyurethane was dried for 3 h at 80° C. prior to use in order to obtain residual moisture content below 0.02% by weight. In order to prevent introduction of moisture via the styrene polymer, quantities used of which were likewise significant, this was likewise dried for 3 h at 80° C. to residual moisture content below 0.05% by weight. 0.9% by weight, based on the thermoplastic polyurethane used, of a thermoplastic polyurethane to which diphenylmethane 4,4′-diisocyanate with average functionality 2.05 had been admixed in a separate extrusion process was added to each example, alongside the two abovementioned components.

(2) Thermoplastic polyurethane used was an ether-based TPU from BASF (Elastollan 1180 A or Elastollan 1185 A) with a Shore hardness 80 A or 85 A according to the data sheet. The styrene polymer used was a PS 158 K Q from BASF with modulus of elasticity 3317 MPa measured in the tensile test according to data sheet or a PS 148 H from BASF with modulus of elasticity 3300 MPa measured in the tensile test according to datasheet.

(3) The thermoplastic polyurethane, the polystyrene, and also the thermoplastic polyurethane to which diphenylmethane 4,4′-diisocyanates have been admixed were respectively metered separately into the intake of the twin-screw extruder by way of gravimetric metering devices. Table 1 lists the proportions by weight of the thermoplastic polyurethane, inclusive of the thermoplastic polyurethane to which diphenylmethane 4,4′-diisocyanate had been admixed, and the polystyrene.

(4) TABLE-US-00001 TABLE 1 Proportions by weight of thermoplastic polyurethane and polystyrene in the inventive examples and comparative examples Example (E)/ Elastollan Elastollan Comparative 1180 A 1185 A PS 158 K Q PS 148 H Example (CE) [% by wt.] [% by wt.] [% by wt.] [% by wt.] E1 90 0 10 0 E2 85 0 15 0 E3 80 0 20 0 E4 70 0 30 0 E5 95 0 5 0 E6 92.5 0 7.5 0 E7 90 0 0 10 E8 85 0 0 15 E9 80 0 0 20 E10 0 85 15 0 CE1 65 0 35 0

(5) The materials were metered into the intake of the twin-screw extruder and then melted and mixed with one another. After mixing, a mixture of CO.sub.2 and N.sub.2 was added as blowing agent. During passage through the remainder of the length of the extruder, the blowing agent and the polymer melt were mixed with one another to form a homogeneous mixture. The total throughput of the extruder, including the TPU, the TPU, to which diphenylmethane 4,4′-diisocyanate with average functionality 2.05 had been added in a separate extrusion process, the polystyrene and the blowing agents, was 80 kg/h.

(6) A gear pump (GP) was then used to force the melt mixture by way of a diverter valve with screen changer (DV) into a pelletizing die (PD), and said mixture was chopped in the cutting chamber of the underwater pelletization system (UP) to give pellets and transported away by the temperature-controlled and pressurized water, and thus expanded. A centrifugal dryer was used to ensure separation of the expanded beads from the processed water.

(7) Table 2 lists the plant-component temperatures used. Table 3 shows the quantities used of blowing agent (CO.sub.2 and N.sub.2), the quantities being adjusted in each case to give the lowest possible bulk density. The quantitative data for the blowing agents are based on the total throughput of polymer.

(8) TABLE-US-00002 TABLE 2 Plant-component temperature data Temper- Temper- Temper- Temper- Water ature ature ature ature Water temper- range in range range range pressure ature extruder of GP of DV of PD in UP in UP (° C.) (° C.) (° C.) (° C.) (bar) (° C.). E1 220-170 150 150 220 15 40 E2 220-170 145 145 220 15 40 E3 220-170 145 145 220 15 40 E4 220-165 145 145 220 15 40 E5 220-170 150 150 220 15 40 E6 220-170 155 155 220 15 40 E7 220-170 145 145 220 15 40 E8 220-170 155 155 220 15 45 E9 220-170 155 155 220 15 40 E10 230-180 180 180 220 15 50 CE1 220-165 145 145 220 15 40

(9) TABLE-US-00003 TABLE 3 Quantities added of blowing agents, based on total throughput of polymer CO.sub.2 [% by wt.] N.sub.2 [% by wt.] E1 2.2 0.1 E2 2.2 0.1 E3 2.2 0.15 E4 2.2 0.15 E5 1.9 0.1 E6 2.15 0.1 E7 1.9 0.15 E8 1.9 0.15 E9 1.9 0.15 E10 2.0 0.15 CE1 2.2 0.15

(10) Table 4 lists the bulk densities of the expanded pellets resulting from each of the inventive examples and comparative examples.

(11) TABLE-US-00004 TABLE 4 Bulk density measured for expanded beads after at least 3 h of storage time Bulk density (g/l) E1 148 ± 6 E2  155 ± 10 E3 175 ± 5 E4 192 ± 5 E5 148 ± 4 E6 154 ± 5 E7 138 ± 7 E8 139 ± 5 E9 190 ± 3 E10 170 ± 7 CE1 215 ± 4

CITED LITERATURE

(12) WO 94/20568 A1 WO 2007/082838 A1, WO2 017/030835 A1 WO 2013/153190 A1 WO 2010/010010 A1 PCT/EP2017/079049 Plastics Additives Handbook, 5th Edition, H. Zweifel, edn., Hanser Publishers, Munich, 2001 ([1]), pp. 98-136 Kunststoff-Handbuch Band 4, “Polystyrol” [Plastics handbook vol. 4, “Polystyrene”], by Becker/Braun (1996) Saechtling (ed.), Kunststoff-Taschenbuch [Plastics handbook], 27th edn., Hanser-Verlag Munich 1998, chapters 3.2.1 and 3.2.4 WO 2014/150122 A1 WO 2014/150124 A1 EP 1979401 B1 US 2015/0337102 A1 EP 2872309 B1 EP 3053732 A WO 2016/146537 A1