Phenolic resin composition for shell molding, resin coated sand for shell molding, and shell mold formed of the same

Abstract

Provided are a phenolic resin composition for shell molding that has low thermal expansion properties and high flexibility, a resin coated sand for shell molding obtained by using the same, and a shell mold formed of the same. The phenolic resin composition for shell molding that is capable of exhibiting advantageous mold characteristic is obtained by a combination of a phenolic resin that is obtained by a reaction of a phenol, a naphthol, and an aldehyde, and a fatty acid amide.

Description

[0001]This application is a divisional of U.S. application Ser. No. 13 / 270,524, filed Oct. 11, 2011, which is a continuation of the International Application No. PCT / JP2010 / 061591 filed on Jul. 8, 2010, which claims the benefit under 35 U.S.C. §119(a)-(d) of Japanese Patent Application 2009-172135, filed on Jul. 23, 2009, the entireties of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a phenolic resin composition for shell molding, a resin coated sand for shell molding, and a shell mold formed of the same. In particular, the present invention relates to a phenolic resin composition for shell molding that simultaneously solves problems related to thermal expansion and flexibility, a resin coated sand obtained by using the phenolic resin composition, and a shell mold obtained by using the resin coated sand.BACKGROUND OF THE INVENTION[0003]Conventionally, in shell-mold casting, there is generally used a shell mold that is formed...

AI Technical Summary

Benefits of technology

The present invention provides a composition for molding shells that has low thermal expansion and high flexibility. This is achieved by using a specific mixture of phenolic resin and fatty acid amide. The resulting mold is less likely to crack and produce defects during casting. Additionally, the use of this composition eliminates the risk of corrosion during the mold-forming process. Overall, the invention improves the quality and safety of the shell molding process.

Problems solved by technology

However, in casting process by using this kind of mold, especially by using a mold which has a complex shape, e.g., a mold for casting a molded product such as a cylinder head of an internal combustion engine, there is a problem that a fracture or a crack (hereinafter referred to as “crack” of the mold) is easily caused on the mold during the casting process using the mold.

However, although such technique has sufficiently solved the problem of crack of the mold, the technique has not sufficiently solved the problem of flexibility.

However, thermal expansion properties and flexibility are not sufficiently improved by this method, and thus further improvement is needed.

However, particularly in the production of such resin by using the hydrochloric acid as a catalyst, there is a safety problem caused by vigorous reaction during the production of the resin, and also there is a problem of corrosion of a die during the production of the mold.

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