Process for the preparation of benzyl ether resins as binders for foundry sands by the cold-box system

摘要

The invention relates to the preparation of phenol-formaldehyde condensation products having a predominantly ortho structure as binders for foundry sands by the cold-box process, by condensation of phenol or phenol derivatives with formaldehyde in an aqueous system in the presence of ortho-directing catalysts, separation of the resultant resin phase, and reaction of the binder blended with sand/polyisocyanate and an amine as curing component to give a sand material.