POLYURETHANE SUPPORT FOR NON-PNEUMATIC TIRE

1 . A non-pneumatic tire having a support structure comprising an outer reinforced annular band, a hub and a set of tension transmitting elements extending between the hub and radially inward from the outer reinforced annular band, the support structure formed at least in part of a polyurethane that is a reaction product of reaction components, the reaction components comprising:

a prepolymer comprising a reaction product of an aromatic diisocyanate monomer and an active hydrogen component selected from a polyol having hydroxyl isocyanate-reacting functional groups, a polyamine having amine isocyanate-reacting functional groups or combinations thereof, the aromatic diisocyanate monomer and the active hydrogen component mixed at a ratio of NCO to the isocyanate-reacting functional groups of at least 1.8:1, wherein the active hydrogen component has a number average molecular weight of between 1000 and 6000 and wherein the prepolymer contains no more than 10 wt % of residual aromatic diisocyanate monomer; and

a curative.

2 . The non-pneumatic tire of claim 1 , wherein an NCO content of the prepolymer is between 2 wt % and 6 wt %.

3 . The non-pneumatic tire of claim 1 or claim 2 , wherein a direct path between the two isocyanate moieties of the aromatic diisocyanate monomer molecule includes only aromatic ring members.

4 . The non-pneumatic tire of any of the preceding claims, wherein the aromatic diisocyanate monomer molecule is symmetrical.

5 . The non-pneumatic tire of any of the preceding claims, wherein the aromatic diisocyanate is selected from PPDI, NDI, TODI, durene diisocyanate or combinations thereof.

6 . The non-pneumatic tire of any of the preceding claims, wherein the aromatic diisocyanate is selected from PPDI.

7 . The non-pneumatic tire of any of the preceding claims, wherein the active hydrogen component comprises isocyanate-reacting functional groups with a functionality of between 1.8 and 3.5.

8 . The non-pneumatic tire of claim 7 , wherein the functionality is between 2 and 3.

9 . The non-pneumatic tire of any of the preceding claims, wherein the active hydrogen component has a number average molecular weight of between 1500 and 5000.

10 . The non-pneumatic tire of any of the preceding claims, wherein the active hydrogen component is PTMEG.

11 . The non-pneumatic tire of any of the preceding claims, wherein the curative is an aliphatic terminated with a hydroxyl function, an amine function or combinations thereof and has a molecular weight of between 40 and 300.

12 . The non-pneumatic tire of claim 11 , wherein the curative is a diol, a diamine or combinations thereof.

13 . The non-pneumatic tire of claim 12 , wherein the curative is selected from 1,2-ethanediol, 1,2-propanediol, 1,4-butanediol or combinations thereof.

14 . The non-pneumatic tire of claim 13 , wherein the aliphatic chain extender is 1,4-butanediol.

15 . The non-pneumatic tire of any of the preceding claims, wherein the prepolymer contains no more than 7 wt % of residual aromatic diisocyanate monomer.

16 . The non-pneumatic tire of claim any of the preceding claims, wherein the polyurethane forms the set of tension transmitting elements.

17 . The non-pneumatic tire of claim 16 , wherein the set of tension transmitting elements are web spokes aligned radially between the hub and the outer annular band.

18 . The non-pneumatic tire of any one of the preceding claims, wherein the set of tension transmitting elements are integral with the hub.