| abstract |
The present invention relates to a process for the production of coated proppants, proppants obtainable by such a process, uses thereof and processes using the proppants. The process for the production of coated proppants comprises the following steps: (a) mixing a proppant with a polyol component and an isocyanate component, wherein the polyol component consists of a phenolic resin and optionally one or more other hydroxy group—containing compounds, wherein the isocyanate component consists of an isocyanate having at least 2 isocyanate groups and optionally one or more other isocyanate group—containing compounds, and (b) curing the mixture obtained in step (a) by treatment with a catalyst; and (c) optionally repeating steps (a) and (b) one or more times, wherein the mixture obtained in the preceding step (b) or the proppant isolated therefrom is used as a proppant in step (a), wherein the polyol component in step (a) is the same as or different from the polyol component used in the previous step (a), and wherein the isocyanate component in step (a) is the same as or different from the isocyanate component used in the previous step (a). |