Abstract The invention covers a method for making reaction injection molded polyurethanes of improved properties. The elastomeric products having superior heat distortion and tear properties comprise the reaction product of an aromatic polyisocyanate, a high molecular weight polyol and a chain extending agent. Said polyol providing said improved properties is a poly(oxybutyleneoxyethylene) glycol having a molecular weight range of about 2,000-6,000. The polyurethane elastomer is prepared by injecting the above three agents through a RIM head into a mold cavity of the desired configuration. Reaction injection molded elastomers are useful as molded articles of commerce including, but not limited to, vehicle body parts.
In a method for making a polyurethane elastomer of significantly improved heat distortion and tear properties wherein a reaction mixture comprising an aromatic polyisocyanate, a high molecular weight polyol and a chain extending agent comprising a low molecular weight active hydrogen-containing compound of at least a functionality of 2 is injected via a RIM machine into a mold cavity of the desired configuration; the improvement which comprises utilizing as said polyol a poly(oxybutyleneoxyethylene) glycol having a molecular weight range of about 2,000-6,000.
Claim 2
Dependent Claim
82 words
In a method for making a polyurethane elastomer of significantly improved heat distortion and tear properties wherein a reaction mixture comprising an aromatic polyisocyanate, a high molecular weight polyol and a chain extending agent comprising a low molecular weight active hydrogen-containing compound of at least a functionality of 2 is injected via a RIM machine into a mold cavity of the desired configuration; the improvement which comprises utilizing as said polyol a poly(oxybutyleneoxyethylene) glycol having a molecular weight range of about 2,000-6,000.
Claim 3
Dependent Claim
39 words
The method of claim 1 wherein said polyol is prepared by reacting a diol initiator having a molecular weight of 400-1,000 first with a mixture of butylene oxide and ethylene oxide followed by a capping reaction with ethylene oxide.
Claim 4
Dependent Claim
22 words
The method of claim 2 wherein said mixture comprises 50-90 mole percent of butylene oxide and 10-50 mole percent of ethylene oxide.
Claim 5
Dependent Claim
23 words
The method of claim 3 wherein sufficient ethylene oxide is added to provide a final polyol containing greater than 85% primary hydroxyl groups.
Claim 6
Dependent Claim
27 words
The method of claim 2 wherein said initiator is a glycol reacted with sufficient butylene oxide or mixed butylene oxide/ethylene oxide to meet the required molecular weight.
Claim 7
Dependent Claim
28 words
The method of claim 4 wherein ethylene oxide is added in an amount of 20-35 weight percent based on the weight of the polyol in said capping reaction.
Claim 8
Dependent Claim
12 words
The method of claim 1 wherein the polyisocyanate comprises 4,4' diphenylmethane diisocyanate.
Claim 9
Dependent Claim
14 words
The method of claim 1 wherein said elastomer is additionally post cured by heating.
Claim 10
Dependent Claim
10 words
The shaped article made by the process of claim 1.