Abstract: A resin is prepared by the reaction of a phenol, an aldehyde and an aliphatic hydroxy compound containing two or more hydroxy groups per molecule in the presence of a divalent metal ion catalyst. These resins react with polyisocyanates to form polyurethanes that are useful binders for foundry cores and molds.
Abstract: A resin is prepared by the reaction of a phenol, an aldehyde and an aliphatic hydroxy compound containing two or more hydroxy groups per molecule in the presence of a divalent metal ion catalyst. These resins react with polyisocyanates to form polyurethanes that are useful binders for foundry cores and molds.
Abstract: Sand cores are removed from metal or plastic coatings by exposing the cores to a humid atmosphere for a sufficient time to weaken the binder of the sand cores. The sand is then shaken from the casting. Metal or plastic castings with hollow passages are produced by forming a casting around the sand core bound with a suitable binder followed by exposing the casting and sand core to a humid atmosphere and then shaking the sand from the casting.
Abstract: Modified benzylic ether resole resins and process for their preparation. The resins are prepared by treating a phenol with a molar excess of aldehyde in the presence of a divalent metal ion catalyst at a pH below 7 followed by further reaction at a pH above 8 in the presence of an alkaline catalyst. Alkaline solutions of the resins are used as foundry binders in an ester cure process.
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