Soft particle foam consisting of thermoplastic polyurethane

Abstract

A foamed pellet material contains a composition (Z1) that contains a thermoplastic polyurethane (TPU-1) and at least one plasticizer (W). The composition (Z1) has a Shore hardness within a range from 15 A to 43 A. A process can produce a foamed pellet material of this kind. The foamed pellet material can be used for the production of a molded article.

Claims

1. A foamed pellet material comprising a composition (Z1) that comprises a thermoplastic polyurethane (TPU-1) and at least one plasticizer (W), the composition (Z1) having a Shore hardness within a range from 15 A to 43 A.

2. (canceled)

3. The foamed pellet material according to claim 1, wherein a melting range of the composition (Z1) begins below 100° C. in a DSC measurement with a heating rate of 20 K/min and in which the composition (Z1) at 180° C. and an applied weight of 21.6 kg in accordance with DIN EN ISO 1133 has a maximum melt flow rate (MFR) of 250 g/10 min.

4. The foamed pellet material according to claim 1, wherein the at least one plasticizer (W) is selected from the group consisting of a derivative of citric acid, a derivative of glycerol, and a mixture of two or more thereof, wherein the derivative of glycerol, if present, has at least one glycerol hydroxyl group which has been esterified with a monocarboxylic acid having 1, 2, 3, 4, 5, or 6 carbon atoms.

5. The foamed pellet material according to claim 1, wherein the at least one plasticizer (W) is present in the composition (Z1) in an amount within a range from 1% to 60% by weight, based on the total composition (Z1).

6. The foamed pellet material according to claim 1, wherein the composition (Z1) comprises the at least one plasticizer (W), and wherein the composition (Z1) comprises an ester of a tricarboxylic acid as a plasticizer (W2).

7. The foamed pellet material according to claim 1, wherein the thermoplastic polyurethane (TPU-1) is produced using a polyol (P1) selected from the group consisting of polyetherols, polyesterols, polycarbonate alcohols, and hybrid polyols.

8. The foamed pellet material according to claim 1, wherein the thermoplastic polyurethane (TPU-1) is produced using a chain extender (KV) selected from the group consisting of 1,2-ethylene glycol, propane-1,3-diol, butane-1,4-diol, and hexane-1,6-diol.

9. The foamed pellet material according to claim 1, wherein the thermoplastic polyurethane (TPU-1) is produced using a diisocyanate selected from the group consisting of diphenylmethane 2,2′-, and 4,4′-diisocyanate (MDI); tolylene 2,4- and 2,6-diisocyanate (TDI); methylenedicyclohexyl 4,4′-, and 2,2′-diisocyanate (H12MDI); hexamethylene diisocyanate (HDI); and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI).

10. A process for producing a foamed pellet material, comprising: (i) providing a composition (Z1) that comprises a thermoplastic polyurethane (TPU-1) and at least one plasticizer (W), the composition (Z1) having a Shore hardness within a range from 15 A to 43 A; (ii) impregnating the composition (Z1) with a blowing agent under pressure; and (iii) expanding the composition (Z1) by means of a pressure drop.

11. A process for producing a foamed pellet material, comprising: (i′) extruding a composition (Z1) that comprises a thermoplastic polyurethane (TPU-1) and at least one plasticizer (W), the composition (Z1) having a Shore hardness within a range from 15 A to 43 A, to obtain a pellet material having an average diameter within a range from 0.2 to 10 mm; (ii′) impregnating the pellet material under pressure with 0.1% to 40% by weight of a blowing agent, based on a total weight of the pellet material, and (iii′) depressurizing to obtain a foamed pellet material.

12. The process according to claim 10, wherein the blowing agent is selected from the group consisting of butane, propane, pentane, carbon dioxide, and nitrogen.

13. A foamed pellet material obtained or obtainable by the process according to claim 10.

14. A method, comprising: producing a molded article with the foamed pellet material according to claim 1.

15. The method according to claim 14, wherein the molded article is produced by fusing or bonding of beads of the foamed pellet material to one another.

16. The method according to claim 14, wherein the molded article is a shoe sole, part of a shoe sole, a bicycle saddle, a cushioning, a mattress, a padding, a backrest, an arm pad, a pad, an underlay, a handle, protective film, a component in automobile interiors, or a component in automobile exteriors.

17. An article, comprising the foamed pellet material according to claim 1, wherein the article is a ball, sports equipment, a floor covering, or a wall paneling.

18. A hybrid material comprising a matrix composed of a polymer (PM) and the foamed pellet material according to claim 1.

19. The process according to claim 11, wherein the blowing agent is selected. from the group consisting of butane, propane, pentane, carbon dioxide, and nitrogen.

20. A foamed pellet material obtained or obtainable by the process according to claim 11.

21. A method, comprising: producing a molded article with the foamed pellet material according to claim 13.

Description

EXAMPLES

[0264] 1. The Following Feedstocks Were Used: [0265] 4,4′-Diphenylmethane diisocyanate [0266] Polytetrahydrofuran having a number-average molar mass of 1 kg/mol [0267] Polybutyl adipate having a number-average molar mass of 2400 g/mol produced from butane-1,4-diol and adipic acid [0268] Polymer diols produced from adipic acid, ethane 2-diol, butane-1,4-diol [0269] Butane-1,4-diol [0270] Ethane-1,2-diol [0271] Phenolic antioxidant [0272] Dioctyl adipate [0273] Tin dioctoate [0274] Hydrolysis stabilizers (oligomeric carbodiimide produced from TMDXI=tetramethylxylyl diisocyanate) [0275] Acetyl tributyl citrate

[0276] 2. Production of TPU Pellets

2.1 Example 1 (Comparison)

[0277] 420 parts of 4,4′-diphenylmethane diisocyanate, 88.8 parts of butane-1,4-diol chain extender, and 700 parts of polytetrahydrofuran having a number-average molar mass of 1 kg/mol are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 21.0° C. In addition, 15.3 parts of a phenolic antioxidant and 25 ppm of a 25% dioctyl adipate solution of tin dioctoate are added as reaction catalyst. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.2 Example 2 (Comparison)

[0278] 312 parts of 4,4′-diphenylmethane diisocyanate, 82.1 parts of butane-1,4-diol chain extender, and 800 parts of polybutyl adipate having a number-average molar mass of 2400 g/mol produced from butane-1,4-diol and adipic acid are synthesized into TPU in a manual casting process. In addition, 6.4 parts of a hydrolysis stabilizer (oligorneric carbodiimide produced from TMDXI=tetramethylxylyl diisocyanate) and 50 ppm of a 25% solution of tin dioctoate are added as reaction catalyst. The slab obtained is heated for 15 hours at 80° C. in an air-circulation oven and then comminuted. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.3 Example 3 (Inventive)

[0279] 393 parts of 4,4′-diphenylmethane diisocyanate, 35.5 parts of ethane-1,2-diol chain extender, and 1000 parts of polytetrahydrofuran having a number-average molar mass of 1 kg/mol and 410 parts of acetyl tributyl citrate are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 210° C. In addition, 15.3 parts of a phenolic antioxidant and 25 ppm of a 25% dioctyl adipate solution of tin dioctoate are added as reaction catalyst. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.4 Example 4 (Inventive)

[0280] 260 parts of 4,4-MDI, 32.2 parts of ethane-1,2-diol chain extender, and 1000 parts of a polymer diol produced from adipic acid, ethane-1,2-diol, and butane-1,4-diol, the latter in a mass ratio of 1:1, having a number-average molar mass of 2000 g/mol, and 231.2 parts of acetyl tributyl citrate are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 210° C. In addition, 10 parts of a hydrolysis stabilizer (oligomeric carbodiimide produced from TMDXI=tetramethylxylyl diisocyanate), 3.08 parts of a phenolic: antioxidant, and 4.62 parts of a lubricant (partly hydrolyzed montan acid esters) are added during, the reaction. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.5 Example 5 (Inventive)

[0281] 260 parts of 4,4′-MDI, 31.6 parts of ethane-1,2-diol chain extender, and 1000 parts of a polymer diol produced from adipic acid, ethane-1,2-diol, and butane-1,4-diol, the latter in a mass ratio of 1:1, having a number-average molar mass of 2000 g/mol, and 260 parts of acetyl tributyl citrate are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 210° C. In addition, 10 parts of a hydrolysis stabilizer (oligomeric carbodiimide produced from tetramethylxylyl diisocyanate), 3.08 parts of a phenolic antioxidant, and 4.62 parts of a lubricant (partly hydrolyzed montan acid esters) are added during the reaction. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.6 Example 6 (Inventive)

[0282] 260 parts of 4,4′-MDI, 32.2 parts of ethane-1,2-diol chain extender, and 1000 parts of a polymer diol produced from adipic acid, ethane-1,2-diol, and butane-1,4-diol, the latter in a mass ratio of 1:1, having a number-average molar mass of 2000 g/mol, and 231.2 parts of acetyl tributyl citrate are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 210° C. In addition, 10 parts of a hydrolysis stabilizer (oligomeric carbodiimide produced from TMDXI=tetramethylxylyl diisocyanate), 3.08 parts of a phenolic antioxidant, and 4.62 parts of a lubricant (partly hydrolyzed montan acid esters) are added during the reaction. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined. The product obtained is heated to 85° C. in a heatable mixer (DiOsa type) and mixed with 25% by weight of glycerol triacetate. After a mixing step of 90 minutes, the product is cooled to room temperature while stirring. The plasticizer is absorbed homogeneously by the TPU. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

2.7 Example 7 (Inventive)

[0283] 260 parts of 4,4′-MDI, 32.2 parts of ethane-1,2-diol chain extender, and 1000 parts of a polymer diol produced from adipic acid, ethane-1,2-diol, and butane-1,4-diol, the latter in a mass ratio of 1:1, having a number-average molar mass of 2000 g/mol, and 231.2 parts of acetyl tributyl citrate are synthesized into TPU in a reaction extruder, the zone temperatures of the extruder being between 140° C. and 210° C. In addition, 10 parts of a hydrolysis stabilizer (oligomeric carbodiimide produced from TMDXI=tetramethylxylyl diisocyanate), 3.08 parts of a phenolic antioxidant, and 4.62 parts of a lubricant (partly hydrolyzed montan acid esters) are added during the reaction. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined. The product is heated to 85° C. in a heatable mixer (DiOsa type) and mixed with 45% by weight of glycerol triacetate. After a mixing step of 180 minutes, the product is cooled to room temperature while stirring. The plasticizer is absorbed homogeneously by the TPU. The pelletized TPU thus produced is used to produce extrusion strands, on which the test values are determined.

[0284] 3. Properties of the Products Obtained

[0285] The tests are carried out in accordance with DIN 53505 (Shore)

TABLE-US-00001 TABLE 1 Shore Tensile Elongation hardness Density strength at break DIN ISO [g/l] [MPa] [%] 7619-1 DIN DIN DIN Examples (3s) 53504-S2 53504-S2 53504-S2 1 (comparative) 86 A 1.12 43 600 2 (comparative) 95 A 1.21 48 520 3 42 A 1.08 15 1100 4 37 A 1.18 12 1150 5 43 A 1.18 27 950 6 35 A 1.19 12 1200 7 29 A 1.19 10 1350

[0286] 4. Production of Bead Foams

[0287] Pelletized TPU samples (examples 1-7) were pressurized with supercritical CO.sub.2 in a high-pressure autoclave in accordance with Table 2, resulting in penetration of CO.sub.2 into the TPU. (he beads were then subjected to a pressure change. During, this pressure change, the CO.sub.2, which had previously been under high pressure, expanded to standard pressure and in this process foamed the partially softened TPU. The sudden cooling caused by the gas expansion resulted in the TPU solidifying into a stable bead foam.

TABLE-US-00002 TABLE 2 Depres- Autoclave Autoclave surization Impregnation temperature pressure pressure time Examples [° C.] [bar] [bar] [hours] 1 (comparative) 120 135 1 4 2 (comparative) 120 135 1 4 3 120 135 1 4 4 120 135 1 4 5 120 135 1 4 6 120 135 1 4 7 120 135 1 4 3 120 200 1 3 4 120 200 1 3 5 120 200 1 3 6 120 200 1 3 7 120 200 1 3 3 130 200 1 3 4 130 200 1 3 5 130 200 1 3 6 130 200 1 3 7 130 200 1 3

TABLE-US-00003 TABLE 3 Autoclave Autoclave temperature pressure Density Examples [° C.] [bar] Appearance [g/l] 1 (comparative) 120 135 minimally foamed 425 2 (comparative) 120 135 minimally foamed 550 3 120 135 well foamed 265 4 120 135 well foamed, 213 rough 5 120 135 foamed 370 6 120 135 well foamed 255 7 120 135 well foamed 238 3 120 200 well foamed 252 4 120 200 well foamed, 217 rough 5 120 200 foamed 324 6 120 200 well foamed 250 7 120 200 well foamed, 232 nonspherical 3 130 200 well foamed 260 4 130 200 well foamed 220 5 130 200 well foamed 308 6 130 200 well foamed 248 7 130 200 well foamed, 238 nonspherical

[0288] 5. Measurement Methods:

[0289] Measurement methods that can be used for the material characterization include the following: DSC, DMA, IMA, NMR, FT-IR, GPC

TABLE-US-00004 Mechanical properties (eTPU) Foam density DIN EN ISO 845: 2009-10 Tear-propagation resistance DIN EN ISO 8067: 2009-06 Dimensional stability test ISO 2796: 1986-08 Tensile test ASTM D5035: 2011 Resilience DIN 53512: 2000-4

CITED LITERATURE

[0290] WO 94/20568

[0291] WO 2007/082838 A1

[0292] WO 2017/030835

[0293] WO 2013/153190 A1

[0294] WO 2010/010010

[0295] WO 2011/141408 A2

[0296] “Kunststoffhandbuch” [Plastics handbook], volume 7, “Polyurethane” [Polyurethanes], Carl Hansel Verlag, 3rd edition, 1993, chapter 3.1.

[0297] Plastics Additive Handbook, 5th edition, H. Zweifel, ed Hanser Publishers, Munich, 2001 ([1]), pages 98-136

[0298] Saechtling (ed.), Kunststoff-Taschenbuch [Plastics handbook], 27th edition, Hanser-Verlag, Munich, 1998, chapters 3.2.1 and 3.2.4

[0299] EP 1979401 B1

[0300] US 2015/0337102

[0301] EP 2872309

[0302] EP 3053732 A

[0303] WO 2016/146537

[0304] “Kunststoffhandbuch” [Plastics handbook], volume 7, “Polyurethane” [Polyurethanes], Carl Hanser Verlag, 3rd edition, 1993, chapter 3

[0305] Piechota and Röhr in “Integralschaumstoff” [Integral foam], Carl-Hanser-Verlag, Munich, Vienna, 1975

[0306] “Kunststoff-Handbuch” [Plastics handbook], volume 7, “Polyurethane” [Polyurethanes], 3rd edition, 1993, chapter 7