Abstract: This invention relates to a resin preparable by reaction of a phenol/formaldehyde novolak with tetraethyl orthosilicate in a mass ratio above 28:1, wherein the phenol of the phenol/formaldehyde novolak is substituted or unsubstituted hydroxybenzene or a mixture of two or more such phenols, and to a particulate material coated with said resin. Said particles can be used e.g. in the shell molding process for the production of shell molds and shell cores; and as proppants for use in the hydraulic fracturing process.

Abstract: This invention relates to a resin preparable by reaction of a phenol/formaldehyde novolak with tetraethyl orthosilicate in a mass ratio above 28:1, wherein the phenol of the phenol/formaldehyde novolak is substituted or unsubstituted hydroxybenzene or a mixture of two or more such phenols, and to a particulate material coated with said resin. Said particles can be used e.g. in the shell molding process for the production of shell molds and shell cores; and as proppants for use in the hydraulic fracturing process.

Abstract: A resin for coating sand and a resin-coated sand produced therefrom wherein the resin is prepared by incorporating furan into a phenolic novolak resin. In the preferred practice, the resin is produced by reaction of furfuryl alcohol with a phenolic compound at an acid pH to give a furfuryl-phenolic intermediate in a first step, and then, in a second step, reacting the furfuryl-phenolic intermediate with a lower aliphatic aldehyde to produce the resin. The resin-coated sands of the present invention provide unexpectedly improved shakeout and collapsibility characteristics in the shell process.

Abstract: A resin for coating sand and a resin-coated sand produced therefrom wherein the resin is prepared by incorporating furan into a phenolic novolak resin. In the preferred practice, the resin is produced by reaction of furfuryl alcohol with a phenolic compound at an acid pH to give a furfuryl-phenolic intermediate in a first step, and then, in a second step, reacting the furfuryl-phenolic intermediate with a lower aliphatic aldehyde to produce the resin. The resin-coated sands of the present invention provide unexpectedly improved shakeout and collapsibility characteristics in the shell process.

Abstract: A resin for coating sand and a resin-coated sand produced therefrom wherein the resin is prepared by incorporating furan into a phenolic novolak resin. In the preferred practice, the resin is produced by reaction of furfuryl alcohol with a phenolic compound at an acid pH to give a furfuryl-phenolic intermediate in a first step, and then, in a second step, reacting the furfuryl-phenolic intermediate with a lower aliphatic aldehyde to produce the resin. The resin-coated sands of the present invention provide unexpectedly improved shakeout and collapsibility characteristics in the shell process.