C. L. Industries Inc.

Ashland Oil, Inc.

Wayne D Woodson

Patrick H Stewart

Curable epoxy resin compositions are described which comprise a mixture of an acid curable epoxy resin and a minor amount of an oxidizing agent capable of reacting with sulfur dioxide to form a catalyst for curing said epoxy resin. The curable epoxy resin composition may contain solid particulate materials. The procedures for curing such epoxy resins as well as methods for forming sand cores and molds also are described. Sand cores and molds produced in accordance with the method of the invention have sufficient strength and hardness after a few seconds of curing for normal foundry applications.

Curable epoxy resin compositions and use in preparing formed, shaped,

Acid-curable resin compositions are described which comprise a mixture of a furan resin and a minor amount of an acid-curable epoxy resin. The acid-curable resin compositions may contain other components such as catalysts, solid particulate materials, etc. The procedures for curing such acid-curable resin compositions as well as methods for forming shaped, filled bodies such as sand cores and molds also are described. Sand cores and molds produced in accordance with the method of the invention exhibit good compression strength, good chemical resistance and increase resistance to stress cracking.

Acid-curable compositions comprising mixtures of furan and epoxy resins

Acid-curable, condensation-type resins, particularly phenolic resin prepolymers and urea-formaldehyde and/or furfuryl alcohol-formaldehyde modified phenolic resin prepolymers, have improved properties when admixed with a dibasic acid di-ester of the composition

Furfuryl esters and resins

Acid-curable furfuryl alcohol prepolymer binders have improved properties when admixed with a dibasic acid di-ester of the composition

Binder compositions comprising furfuryl ester and furfuryl ester-furuyl

A peroxide system or composition for use in resin polymerization consists of 1,4-diisopropylbenzene monohydroperoxide dissolved in an organic solvent which is a solvent for hydrogen peroxide and 1,4-diisopropylbenzene dihydroperoxide. The peroxide composition is characterized by its storage stability, resistance to detonation, low flammability, ease of handling and improved catalytic properties in the polymerization of certain resins. The preferred peroxide, based on economic considerations, is a crude diisopropylbenzene hydroperoxide mixture comprising a major amount of 1,4-diisopropylbenzene monohydroperoxide and a minor amount of 1,4-diisopropylbenzene dihydroperoxide, together with solvents and unreacted materials obtained as a byproduct in the commercial manufacture of p-diisopropylbenzene dihydroperoxide. A particularly stable and useful composition consists of about 20% solvent, preferably cyclohexanone, and 80% of a mixture consisting of a major part of crude diisopropylbenzene hydroperoxide and a minor part of hydrogen peroxide. This peroxide composition, and the 1,4-diisopropylbenzene monohydroperoxide, or the crude diisopropylbenzene hydroperoxide, are soluble in or miscible with furfuryl alcohol-formaldehyde resin prepolymers. The peroxide composition and the resin prepolymer are added to sand, formed into cores or molds, and gassed with sulfur dioxide, and optionally purged with air, at a temperature from room temperature to about 300.degree. F. for a time a fraction of a second to several minutes to form superior sand cores and molds.

Organic hydroperoxide catalyst system

A method of producing sand cores or molds for foundry use involves coating the sand with a novel acid catalyst composition and adding acid-curing, condensation-type resin. A novel acid catalyst composition comprises the mixture of a sulfonic acid such as benzene sulfonic acid, toluene sulfonic acid or xylene sulfonic acid, or mixtures thereof, with 0.5-20% wt. perchloric acid. A catalyst of this composition, when admixed with foundry sand and an acid-curing condensation-type resin, is a novel composition characterized by rapid cure and high tensile strength and hardness in the resulting resin-bound sand core or mold. Sand cores or molds made using this catalyst/sand/resin composition are further characterized by low emissions of oxidizable gaseous organic constituents.

Acid catalysis of resin foundry binders

Sand molds or cores are prepared by coating sand particles with an acid-curing condensation type resin consisting of poly furfuryl alcohol or admixtures of poly furfuryl alcohol with other acid-curing resins. The resin composition is formed into a desired shape and is cured at ambient temperature over a period of between a few seconds and a few minutes by means of an acid produced by in situ oxidation of sulfur dioxide. Sulfur dioxide is introduced into the molding composition together with an oxidizing agent which effects oxidation of the sulfur dioxide within the mold or core composition. Preferably, the oxidizing agent is an organic peroxide incorporated on the sand or introduced with the resin composition. The formation of sand cores or molds from resins comprising poly furfuryl alcohol results in products having improved tensile strengths, improved hardness, and characterized by virtually no migration or furfuryl alcohol polymers to or coating of the molds or patterns used in sand core or mold preparation.

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Danville, IL, United States of America

Wayne D Woodson