FOAMS BASED ON THERMOPLASTIC ELASTOMERS

Abstract

Bead foams may be made of thermoplastic polyurethane and polyethylene(s), and moldings produced therefrom, may made of a composition with (a) 60 to 90 wt. % thermoplastic polyurethane and (b) 10 to 40 wt. % of polyethylene, relative to a total 100% by weight. The bead foams and moldings may be produced and/or used for shoe intermediate soles, shoe insoles, shoe combisoles, cushioning elements for shoes, bicycle saddles, bicycle tires, damping elements, cushioning, mattresses, underlays, grips, protective films, in components in the automobile-interior sector or automobile-exterior sector, balls and sports equipment, or as floor covering.

Claims

1. A bead foam made of a composition (Z) comprising (a) 60 to 90 wt. % of thermoplastic polyurethane as component I; and (b) 10 to 40 wt. % of polyethylene as component II; wherein an entirety of the components I and II provides 100 wt.

2. The foam of claim 1, comprising: (a) 60 to 85 wt. % of the thermoplastic polyurethane as the component I; (b) 15 to 40 wt. % of the polyethylene as the component II.

3. The foam of claim 1, wherein an average diameter of beads of the foam is from 0.2 to 20 mm.

4. A process for producing a molded body made of the foam of claim 1, comprising impregnating the composition (Z); with a blowing agent under pressure, to obtain an impregnated composition; and expanding the impregnated composition by a pressure decrease.

5. A molded body, made of the foam of claim 1.

6. The body of claim 5, having tensile strength above 600 kPa.

7. The body of claim 5, having an elongation at break above 100%.

8. The body of claim 5, having a compressive stress at 10% compression above 15 kPa.

9. The body of claim 5, having a density in a range of from 75 to 375 kg/m.sup.3.

10. The body of claim 5, having a rebound resilience above 55%.

11. The body of claim 5, which is an intermediate sole, an insert configured for a shoe, or a cushioning element configured for a shoe, wherein the shoe is an outdoor shoe, sports shoe, sandal, boot, or safety shoe.

12. A process for producing the body of claim 5, the method comprising: introducing beads of the foam into a mold; fusing the the plurality in the mold.

13. A shoe, comprising the body of claim 5.

14. An article selected from the group consisting of a shoe intermediate sole, shoe insole, shoe combisole, shoe cushioning element, bicycle seat, bicycle tire, damping element, cushioning, mattress, underlay, grip, protective film, automobile-interior component, automobile-exterior component, ball, sports equipment, and floor covering, comprising: the foam of claim 1.

15. The article of claim 14, which is a shoe intermediate sole, shoe insole, shoe combisole, or shoe cushioning element.

16. The foam of claim 1, wherein the thermoplastic polyurethane has a weight-average molar mass of at least 60,000 g/mol.

17. The foam of claim 1, having an average diameter in a range of from 1 to 12 mm.

18. The foam of claim 1, comprising (a) 65 to 80 wt. % of the thermoplastic polyurethane as component I; and (a) 20 to 35 wt. % of the polyethylene as component II.

Description

EXAMPLES

[0207] The expanded beads made of thermoplastic polyurethane and of the polyethylene 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 polyethylene, 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. 0.6% 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.

[0208] Thermoplastic polyurethane used was an ether-based TPU from BASF (Elastollan 1180 A) with a Shore hardness 80 A according to the data sheet. The polyethylene used was Lupolen 4261AG from Lyondellbasell.

[0209] The thermoplastic polyurethane, the polyethylene, 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.

[0210] 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 polyethylene.

[0211] Table 1: Proportions by weight of thermoplastic polyurethane and polyethylene in the examples Elastollan 1180 A Lupolen 4261AG

TABLE-US-00001 TABLE 1 Proportions by weight of thermoplastic polyurethane and polyethylene in the examples Elastollan 1180 A Lupolen 4261AG Example (E) [% by wt.] [% by wt.] E1 90 10 E2 85 15 E3 80 20 E4 70 30

[0212] 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.

[0213] 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 polyethylene and the blowing agents, was 80 kg/h.

[0214] 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.

[0215] 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.

TABLE-US-00002 TABLE 2 Plant-component temperature data Temper- Temper- Temper- Temper- Water ature ature ature ature Water temper- range range range range pressure ature in extruder of GP of DV of PD in UP in UP (° C.) (° C.) (° C.) (° C.) (bar) (° C.). C1 225-185 165 165 220 15 40 C2 225-195 165 165 220 15 40 C3 225-195 170 170 220 15 40 C4 225-195 180 180 220 15 40

TABLE-US-00003 TABLE 3 Quantities added of blowing agents, based on total throughput of polymer CO.sub.2 N.sub.2 [% by wt.] [% by wt.] C1 1.80 0.1 C2 1.80 0.1 C3 1.80 0.1 C4 1.80 0.15
Table 4 lists the bulk densities of the expanded pellets resulting from each of the examples.

TABLE-US-00004 TABLE 4 Bulk density achieved for expanded beads after about 3 h of storage time Bulk density (g/l) C1 150 ± 4 C2 152 ± 6 C3 144 ± 10 C4 140 ± 7

CITED LITERATURE

[0216] WO 94/20568 A1 [0217] WO 2007/082838 A1, [0218] WO2017/030835 A1 [0219] WO 2013/153190 A1 [0220] WO 2010/010010 A1 [0221] PCT/EP2017/079049 [0222] Plastics Additives Handbook, 5th Edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001 ([1]), p. 98-p. 136 [0223] Kunststoff-Handbuch Vol. 4, “Polystyrol” [Plastics handbook vol. 4, “Polystyrene” ], Becker/Braun (1996) [0224] Saechtling (ed.), Kunststoff-Taschenbuch [Plastics handbook], 27th edn., Hanser-Verlag Munich 1998, chapters 3.2.1 and 3.2.4 [0225] WO 2014/150122 A1 [0226] WO 2014/150124 A1 [0227] EP 1979401 B1 [0228] US 2015/0337102 A1 [0229] EP 2872309 B1 [0230] EP 3053732 A [0231] WO 2016/146537 A1