Why polyurethane(PU) tooling board is more popular than epoxy tooling board?

Both of pu tooling board and epoxy tooling board have similar physical characteristics,can be used for prototyhpe,foundry pattern,model,mold,checking fixtures. However, people often choose pu board than epoxy board. Why? Maybe some features of pu tooling boards tells:

1.Less dust,environmentally friendly- more chips when machining for a better working environment;

2.Lasts much longer than epoxy board;

3.Will not crack, rot or peel from outside exposure;

4. Better toughness, have a fine strcture.

5. Production circle of pu tooling board is shorter.

Of course,polyurethane(PU) tooling board is more popular than epoxy tooling board, but epoxy resin is more popular than pu resin in other industries,sharing more market.