Furan-phenolic resin coated sand for collapsible foundry molds
AssigneeCPC International Inc.
InventorRobert Laitar
Life of this patent
Estimating the term…
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.
Claims12
A resin coated sand comprising:
- 1. particles of sand coated with from about 1% to about 8% by weight of the sand of a furan-modified novolak resin prepared by
- a. reacting of furfuryl alcohol with a phenol at an acid pH;
- with the mole ratio of furfuryl alcohol to the phenol being within the range of 0.04 to 0.9, to produce a furfuryl-phenolic intermediate, and
- b. reacting of said intermediate with a C.sub.1 to C.sub.3 aliphatic aldehyde at an acid pH, with the molar ratio of aldehyde to the total of the phenol and furfuryl alcohol being within the range of 0.5 to 0.85
- c. and separating the resin;
- and
- 2. a curing agent.
A resin coated sand comprising:
- 1. particles of sand coated with from about 1% to about 8% by weight of the sand of a novolak resin prepared by
- a. reacting a furan compound selected from the group consisting of furfuryl alcohol and furfural with a phenol in the presence of a catalyst to promote a condensation reaction of the furan compound with the phenol, with the mole ratio of the furan compound to the phenol being within the range of 0.04 to 0.9, to produce a furan-phenolic intermediate,
- b. reacting said intermediate with a C.sub.1 to C.sub.3 aliphatic aldehyde in the presence of a catalyst to promote a condensation reaction between the aldehyde and the intermediate, with the mole ratio of the aldehyde to the total of the phenol and furan compound being within the range of 0.5 to 0.85,
- c. and separating the resin;
- and
- 2. a curing agent.
A resin coated sand comprising:
- 1. particles of sand coated with from about 1% to about 8% by weight of a resin prepared by:
- a. providing a furan-containing resin selected from the group consisting of:
- i. a furan resin prepared by reaction of furfuryl alcohol with a C.sub.1 to C.sub.3 aliphatic aldehyde, and
- ii. a furan modified resin prepared by reaction of a phenol and a C.sub.1 to C.sub.3 aliphatic aldehyde to produce a resole resin and then reacting the resole resin with furfuryl alcohol;
- and
- b. blending with the furan-containing resin with a novolak resin prepared by reaction of a phenol with a C.sub.1 to C.sub.3 aliphatic aldehyde,
- with the ratio of the toal of the aldehyde contained in the furan-containing resin and the novolak resin to the phenol of the novolak resin and the furfuryl alcohol of the furan-containing resin being within the range of 0.5 to 0.85 and the ratio of furfuryl alcohol of the furan-containing resin to the phenol of the novolak resin is within the range of 0.04 to 0.9;
- and
- 2. a curing agent.
Dependencies are inferred from the claim text.