Patent ID: 9562187
Date: 2017-02-07
CPC Classifications: C09K

Claim:
1. A method for the production of proppant that is coated with a polymeric coating, the method comprising: (a) coating free-flowing proppant solids in a mixer with a first component comprising a polyol; (b) adding to the mixer a second component comprising an isocyanate that has at least 2 reactive isocyanate groups and which is added at a controlled rate and volume sufficient to form a polymeric coating on said proppant solids; and (c) adding water to the mixer at about the time the isocyanate has begun to be added to the mixer at a rate and volume sufficient to retain the free-flowing characteristics of said proppant solids and addition of the water to the mixer does not conclude until all isocyanate has been added.