Memory foam based on thermoplastic polyurethane

Abstract

The present invention relates to a process for producing a molding (FK), comprising the production of a thermoplastic polyurethane, comprising the reaction of at least one polyisocyanate composition, at least one chain extender, and at least one polyol composition, the production of a molding (FK*) from the thermoplastic polyurethane, the heating of the molding (FK*) to a temperature below the temperature at which the molding (FK*) is permanently deformable, and above the switching temperature of the thermoplastic polyurethane, the compressing of the heated molding (FK*) to give a molding (FK), and the cooling of the molding (FK) to a temperature below the switching temperature of the thermoplastic polyurethane, and also to the moldings obtainable or obtained by such a process.

Claims

1. A process for producing a molding (FK), comprising: (a) preparing a thermoplastic polyurethane, comprising the reaction of (i) at least one polyisocyanate composition; (ii) at least one chain extender; and (iii) at least one polyol composition, the polyol composition comprising at least one bisphenol derivative selected from the group consisting of bisphenol A derivatives having a molecular weight Mw>315 g/mol and bisphenol S derivatives having a molecular weight Mw>315 g/mol, at least one of the OH groups of the bisphenol derivative being alkoxylated; (b) producing a molding (FK*) from the thermoplastic polyurethane, (c) heating the molding (FK*) to a temperature below the temperature at which the molding (FK*) is permanently deformable, and above the switching temperature of the thermoplastic polyurethane, (d) compressing the heated molding (FK*) to give a molding (FK), and (e) cooling the molding (FK) to a temperature below the switching temperature of the thermoplastic polyurethane, wherein the molding is a foam, and wherein the chain extender (ii) is a diol having a molecular weight Mw<220 g/mol.

2. The process according to claim 1, wherein the thermoplastic polyurethane is a bead foam or an extruded foam.

3. The process according to claim 1, wherein the beginning of permanent deformability corresponds to the beginning of melting of the hard phase of the thermoplastic poly urethane, and the switching temperature corresponds to the beginning of the phase transition highest in terms of temperature before the inciting range.

4. The process according to claim 1, wherein the switching temperature of the thermoplastic polyurethane (T.sub.switch) is in the range from 0 to 120 C.

5. The process according to claim 1, wherein the extent of the molding (FK) obtained in (d) in at least one dimension is not more than 75% of the extent of the molding (FK*).

6. The process according to claim 1, wherein the chain extender (ii) and the bisphenol derivative present in the polyol composition are used in a molar ratio of 40:1 to 1:10.

7. The process according to claim 1, wherein the at least one bisphenol derivative has the following formula (I): ##STR00007## wherein R1 independently at each occurrence is a methyl group or H, R2 and R3 are a methyl group, or R2-CR3 together are OSO, X is a group C(R1).sub.2-, C(R1).sub.2-C(R1).sub.2- or C(R1).sub.2-C(R1).sub.2-C(R1).sub.2-, p and q independently of one another are an integer from 1 to 4, and n and m independently of one another are an integer >0.

8. The process according to claim 1, wherein the at least one bisphenol derivative comprises only primary OH groups.

9. The process according to claim 1, wherein the polyol composition comprises a polyol selected from the group consisting of polyetherols, polyesterols, polycarbonate alcohols and hybrid polyols.

10. The process according to claim 1, wherein the polyisocyanate is an aromatic diisocyanate.

11. The process according to claim 1, wherein the polyisocyanate is an aliphatic diisocyanate.

12. The process according to claim 1, wherein the molding (FK) undergoes restoration by heating to a temperature above the switching temperature.

Description

EXAMPLES

(1) Ingredients Used were as Follows: Polyol 1: polyether polyol with an OH number of 113.3 and exclusively primary OH groups (based on tetramethylene oxide, functionality: 2) Polyol 2: bisphenol A-started polyether polyol with an OH number of 313 and exclusively primary OH groups, functionality: 2 Polyol 3: polyester polyol based on adipic acid MEG with MW 470 g/mol and an OH number of 240, functionality: 2 Isocyanate 1: aliphatic isocyanate (4,4-methylenedicyclohexyl diisocyanate) Isocyanate 2: aromatic isocyanate (4,4-methylenediphenyl diisocyanate) CE: 1,4-butanediol Catalyst 1: tin(II) isooctoate (50% in dioctyl adipate) Stabilizer 1: sterically hindered phenol Additive 1: ester wax

1. General Preparation Example

(2) The polyols were charged to a vessel at 80 C. and mixed with the components as per Tables 1 and 2 with vigorous stirring. The reaction mixture underwent heating to more than 110 C., at which point it was poured out onto a heated, Teflon-coated bench. The cast slab obtained was heat-treated at 80 C. for 15 hours, then pelletized. The resulting extruded pellets had a particle weight of 34-37 mg.

(3) TABLE-US-00001 TABLE 1 Comparative Number 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polyol 1 [g] 700 490 280 970 900 800 700 Polyol 2 [g] 0 210 420 30 100 200 300 Polyol 3 [g] 0 0 0 0 0 0 0 Isocyanate 1 [g] 588.00 675.3 763.39 Isocyanate 2 [g] 510.18 533.93 567.85 601.78 CE [g] 183.33 147.72 151.91 90.56 91.99 94.02 96.06 Catalyst 1 571 L 609 L 646 L Stabilizer 1 [g] 7.18 7.67 16.16 16.42 16.78 17.14 Additive 1 [g] 2.87 3.07 Index 1000 1000 1020 1000 1000 1000 1000 Hard segment 37.90% 37.90% 36.78% 21.37% 21.37% 21.37% 21.37% content Initiation 80 C. 80 C. 80 C. 80 C. 80 C. 80 C. 80 C. temperature Casting 110 C. 110 C. 110 C. 110 C. 110 C. 110 C. 110 C. temperature Time 80-110 C. 3 min 3 min 7 min 1 min 1 min 51 sec 44 sec 30 sec 05 sec 00 sec

(4) TABLE-US-00002 TABLE 2 Number Comparative 2 Example 7 Comparative 3 Polyol 1 [g] 800 320 623.08 Polyol 2 [g] 0 480 0 Polyol 3 [g] 0 0 127 Isocyanate 1 [g] Isocyanate 2 [g] 400 561.31 690 CE [g] 71.32 80.91 157.40 Catalyst 1 571 L 609 L 646 L Stabilizer 1 [g] 12.84 14.57 16.14 Additive 1 [g] Index 1000 1000 1000 Hard segment 21.20% 21.20% 37.87% content Initiation 80 C. 80 C. 80 C. temperature Casting 110 C. 110 C. 110 C. temperature Time 80-110 C. 1 min 05 sec 42 sec 1 min 21 sec

(5) Foam elements were produced from the samples by means of bead foam expansion and subsequent steam welding or foam extrusion.

2. Production of Foam Beads by the Suspension Process

(6) The experiments were conducted with a tank fill occupancy of 80%.

(7) 100 parts by weight (corresponding to 27.5 wt %, based on the overall suspension without blowing agent) of the pellets, 257 parts by weight (corresponding to 70.6 wt %, based on the overall suspension without blowing agent) of water, 6.7 parts by weight (corresponding to 1.8 wt %, based on the overall suspension without blowing agent) of calcium carbonate, 0.13 part by weight (corresponding to 0.04 wt %, based on the overall suspension without blowing agent) of a surface-active substance, and 24 parts by weight of butane as blowing agent (24%, based on the quantity of pellets used) were heated with stirring. Then, additionally, nitrogen was injected into the liquid phase at 50 C. and the internal pressure was adjusted to 8 bar. Subsequently, when the impregnating temperature (IMT) of 125 C. is reached, depressurization is carried out using a depressurizing apparatus.

(8) The adhering suspension assistants (calcium carbonate and surfactant) are subsequently removed with dilute nitric acid, the foam beads are washed with deionized water, and the washed beads are then dried.

(9) The resulting bulk density (BD) was ascertained thereafter.

(10) TABLE-US-00003 TABLE 3 Produced by suspension Resulting bulk density Sample process [g/l] Comparative 2 + 89 Example 3 + 89 Example 4 + 84 Example 5 + 86 Example 6 + 86

3. Production of Molded Parts

(11) The foam beads produced as described above were introduced into a preheated mold under pressure and with compaction. This mold was heated reciprocally with steam from 1.0 to 4.0 bar, i.e., at temperatures from 100 C. to 140 C.

(12) The pressure in the mold was then removed, the mold was cooled with water and/or air and opened, and the mechanically stable molded part was removed.

4. Production of an Extruded Foam

(13) The formulas specified in Table 5 were processed using the extrusion line described below, with addition of blowing agents Treib1 and Treib2, to give foam sheets approximately 2 mm thick. 8 foam sheet strips were subsequently stacked to a thickness of 1.5 cm and fixed using PU binder. The expansion behavior was determined on these slabs. Treib1: concentrate of sodium hydrogencitrate (32%) and sodium hydrogencarbonate (24%) in ethylene-vinyl acetate copolymer (EVA) Treib2: PS/SAN microspheres in EVA

5. Extrusion Procedure

(14) The samples characterized in Table 5 were processed to sheets on a Brabender single-screw extruder with flat sheet die.

(15) Prior to the extrusion, the pellets were mixed with 3 wt % of Treib1 and 9 wt % of Treib2 and extruded in the form of a dry blend.

(16) Extruder: Brabender Plasti-Corder PLE 331

(17) L/D ratio: L=25 D

(18) Screw diameter: D=19 mm

(19) Screw compression ratio: 3:1

(20) Die: flat die

(21) Extrusion type: sheet

(22) Further extrusion conditions are evident from the table below:

(23) TABLE-US-00004 TABLE 4 Temperature profile [ C.] ST No. Z 1 190 Z 3 Z 4 Z 5 [Nm] Remarks C1 200 210 210 190 190 5 homogeneous C2 200 200 200 180 180 10 homogeneous C3 210 210 210 190 190 6 inhomogeneous, rough B1 210 215 215 200 200 5 homogeneously foamed B2 210 210 210 185 185 5 homogeneous, stiff B6 200 210 210 180 180 8 homogeneous B7 210 210 210 190 190 4 homogeneous, stiff ST = torque at the screw

(24) TABLE-US-00005 TABLE 5 Production by the extrusion Resulting sample density Sample process [g/l] Comparative 1 + 280 Comparative 2 + 220 Comparative 3 + 250 Example 1 + 280 Example 2 + 250 Example 6 + 230 Example 7 + 290

6. Determination of Expansion Behavior

(25) Sample specimens 15 mm thick were heated in a heating cabinet at 50 C. or 70 C. for 2 h and while still hot were compressed to a thickness of 7.5 mm using a pressing apparatus. The specimens were left in the pressing apparatus for 12 hours, and underwent cooling to room temperature. The specimens were then removed from the apparatus, at which point they relaxed to sample thickness 1, at which they could be stably stored for days. To test the resilience, the specimens were immersed into hot water at 90 C. for 1 minute. During this procedure, the samples of the invention expanded again to the thickness 2.

(26) TABLE-US-00006 TABLE 6 Relaxation behavior of the samples after heating at 50 C. Thickness 1 Thickness 1 Expansion from after compression as % of thickness 1 to at 50 C. and original Observation Expansion to thickness 2 in % Sample cooling to RT thickness in hot water thickness 2 (thickness 1 = 100%) Comparative 1 13 mm 87% no expansion extrusion Comparative 2 14 mm 93% no expansion extrusion Comparative 2 14 mm 93% no expansion suspension Comparative 3 12 mm 80% no expansion extrusion Example 1 12 mm 80% expansion 14.5 mm 121% extrusion Example 2 12 mm 80% expansion 15 mm 125% extrusion Example 3 13 mm 87% slight expansion 14 mm 107% suspension Example 4 12 mm 80% rapid expansion 15 mm 125% suspension Example 5 11 mm 73% rapid expansion 15 mm 136% suspension Example 6 11 mm 73% slow expansion 14 mm 127% suspension Example 6 11 mm 73% slow expansion 14 mm 127% extrusion Example 7 10 mm 66% slow expansion 14 mm 140% extrusion

(27) TABLE-US-00007 TABLE 7 Relaxation behavior of the samples after heating at 70 C. Thickness 1 Thickness 1 Expansion from after compression as % of thickness 1 to at 50 C. and original Observation Expansion to thickness 2 in % Sample cooling to RT thickness in hot water thickness 2 (thickness 1 = 100%) Comparative 1 11 mm 73% no expansion extrusion Comparative 2 12 mm 80% no expansion suspension Comparative 2 12 mm 80% no expansion extrusion Comparative 3 10 mm 66% no expansion extrusion Example 1 11 mm 73% expansion 14 mm 127% extrusion Example 2 11 mm 73% expansion 15 mm 136% extrusion Example 3 12 mm 80% slight expansion 13.5 mm 112% suspension Example 4 11 mm 73% rapid expansion 15 mm 136% suspension Example 5 11 mm 73% rapid expansion 15 mm 136% suspension Example 6 10 mm 66% rapid expansion 15 mm 150% suspension Example 6 10 mm 66% rapid expansion 15 mm 150% extrusion Example 7 9 mm 60% rapid expansion 15 mm 166% extrusion