Low-damping polyurethane elastomer
The present invention relates to a method of preparing a polyurethane elastomer, said method comprising the step of reacting at least one isocyanate composition (ZI) and one polyol composition (ZP) comprising a poly-ε-caprolactone polyol and an α-hydro-ω-hydroxy-poly(oxytetramethylene) polyol to obtain an isocyanate-functional prepolymer and the step of reacting the prepolymer obtained as per step (i) with at least one chain extender (KV). The present invention further relates to a polyurethane elastomer obtained or obtainable according to a method of the invention and also to the method of using a polyurethane elastomer according to the invention or a polyurethane elastomer obtained or obtainable according to a method of the invention in the manufacture of a shaped article, especially a damping element, a shock absorber or a stop buffer or part of a shoe or of a shoe sole, for example part of an insert sole or of a midsole.
1. A method of preparing a polyurethane elastomer, comprising (i) and (ii):
(i) reacting at least one isocyanate composition (ZI) and one polyol composition (ZP) comprising a poly-ε-caprolactone polyol and an α-hydro-ω-hydroxypoly(oxytetramethylene) polyol to obtain an isocyanate-functional prepolymer, and
(ii) reacting the prepolymer obtained in (i) with at least one chain extender (KV) in the presence of a blowing agent.
2. The method according to claim 1 , wherein the reacting in (i) is performed such that the prepolymer obtained in (i) has an isocyanate (NCO) content in the range from 2% to 8%.
3. The method according to claim 1 , wherein the reacting in (i) is effected at a temperature in the range from 110° C. to 180° C.
4. The method according to claim 1 , wherein the reacting in (i) is performed such that the prepolymer obtained in (i) has an isocyanate (NCO) content in the range from 8% to 22%.
5. The method according to claim 1 , wherein the reacting in (i) is effected at a temperature in the range from 40° C. to 110° C.
6. The method according to claim 1 , wherein the reacting in (ii) is performed in the presence of at least further component selected from the group consisting of a polyol, water, a chain-extending agent, a crosslinking agent, a catalyst, and an auxiliary.
7. The method according to claim 1 , wherein the poly-ε-caprolactone polyol is obtained by reacting ε-caprolactone and a starter molecule that is a diol having a number average molecular weight in the range from 80 to 1500 g/mol.
8. The method according to claim 1 , wherein the poly-ε-caprolactone polyol is obtained by reacting ε-caprolactone and at least one starter molecule selected from the group consisting of an α-hydro-ω-hydroxypoly(oxytetramethylene)diol, a polyethylene glycol and a polypropylene glycol.
9. The method according to claim 1 , wherein the polyol composition comprises the α-hydro-ω-hydroxypoly(oxytetramethylene) polyol in an amount in the range from 0.1 to 50 wt %, based on the polyol composition.
10. The method according to claim 1 , wherein the isocyanate composition comprises at least one isocyanate selected from the group consisting of 1,5-naphthylene diisocyanate (NDI), 4,4′-diphenylmethane diisocyanate (MDI), p-phenyl diisocyanate (PPDI) and o-tolidine diisocyanate (TODI).
11. The method according to claim 1 , wherein the isocyanate composition comprises 1,5-naphthylene diisocyanate (NDI) in an amount ranging from 90 to 100 wt % based on the entire isocyanate composition.
12. The method according to claim 1 , wherein the chain extender (KV) is at least one selected from the group consisting of water, a diol having a molecular weight in the range from 50 to 500 g/mol, a triol having a molecular weight in the range from 50 to 500 g/mol and a diamine having a molecular weight in the range from 50 to 500 g/mol.
13. The method according to claim 1 , wherein the poly-ε-caprolactone polyol and/or the α-hydro-ω-hydroxypoly(oxytetramethylene) polyol have a number average molecular weight in the range from 1500 to 2500 g/mol.
14. A polyurethane elastomer obtained by a method that comprises (i) and (ii):
(i) reacting at least one isocyanate composition (ZI) and one polyol composition (ZP) comprising a poly-ε-caprolactone polyol and an α-hydro-ω-hydroxypoly(oxytetramethylene) polyol to obtain an isocyanate-functional prepolymer, and
(ii) reacting the prepolymer obtained in (i) with at least one chain extender (KV) in the presence of a blowing agent.
15. The polyurethane elastomer according to claim 14 wherein the polyurethane elastomer is microcellular.
16. The polyurethane elastomer according to claim 14 having a density in the range from 0.12 to 0.8 g/cm 3 according to DIN EN ISO 845.
17. A shaped article comprising the polyurethane elastomer according to claim 14 .
18. The shaped article according to claim 17 , which is a damping element, a shock absorber, a stop buffer, or part of a shoe.
19. The method according to claim 1 , wherein the (Z1) component consists of 1,5-napththylene diisocyanate and the polyol component (ZP) consists of poly-ε-caprolactone polyol and α-hydro-ω-hydroxypoly(oxytetramethylene) polyol.
20. The method according to claim 19 , wherein the polyol component (ZP) comprises 15-25% by weight of α-hydro-ω-hydroxy-poly(oxytetramethylene).