Honda Motor Co., Ltd.

Asahi Organic Chemicals Industry Co., Ltd.

Hiroshi Furusawa

Masanori Totsuka

Hiromi Fujita

Keita Yoshiara

Ken Tomeba

Naohisa Shibata

Mitsuaki Ueno

In the sand core, the tar reducing agent is included in at least the second coating layer, which is the outermost layer, of the coating layersand. Thus, the tar, which may be generated from the core bodyand the coating layersandwhich are positioned thereinside, can be decomposed into low molecular gases (carbon monoxide, carbon dioxide, water, and the like) by heat of the molten metal. As a result, generation of the tar from the sand coreto the outside can be prevented. In this case, since the layer which includes the tar reducing agent is the second coating layerwhich directly contacts the molten metal, the second coating layercan directly receive the heat of the molten metal, and the tar generation prevention effects can be thereby remarkably obtained. Therefore, generation of defects in cast products which may be caused by clogging in the gas drain can be prevented, and structures of the gas drain of the die and the surroundings thereof can be simplified.

Sand core for casting and process for producing the same

To provide resin-coated sand for a multilayer mold in which the consolidation strength of the casting mold obtained by using it and gas permeability thereof are improved at the same time, the amount of occurrence of pyrolytic products (tar, soot and the like) derived from organic substances is effectively inhibited, when molding is performed using such a casting mold, and further, the casting mold after molding can exhibit excellent collapsibility. Disclosed is resin-coated sand for a multilayer mold, in which surfaces of refractory particles are coated with a binder composition containing a phenolic novolak resin having an ortho/para bond ratio of methylene groups of 1.5 or more and an aromatic amine as indispensable constituents, and the grain fineness number is from 80 to 150.

Resin-coated sand for multilayer mold

It is an object of the present invention to provide a phenolic novolak resin for a shell mold which is capable of simultaneously solving a problem of gas defect caused by a tar generated at the time of casting and a problem of a casting defect represented by veining. As the phenolic novolak resin in RCS for the shell mold, there is used a copolycondensation resin-type phenolic novolak resin obtained by reacting a phenol and an alkylphenol, with at least one of aldehydes, wherein a ratio of an ortho-bond to a para-bond of a methylene group in the phenolic novolak resin is not less than 1.5, and a fire-resisitant particle is coated with this resin.

Phenolic novolak resin for shell mold, process for producing the same, and resin coated sand

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Aichi, Japan

Hiroshi Furusawa