Nissan Motor Company Limited

Mitsui Toatsu Chemicals, Incorporated

Koue Ohkawa

Takashi Seino

Shin Fujii

Kazumi Tanaka

Akira Oyamada

Isao Suyama

A resin composition for bonding of foundry sand, said composition comprising as a resin component a crystalline unsaturated polyester being solid and substantially tack-free at room temperature and having an acid value of 15 to 100, said unsaturated polyester being prepared by polymerizing (A) a dicarboxylic acid component containing 10 to 50 mole % of terephthalic acid, an alkyl terephthalate, isophthalic acid or an alkyl isophthalate and 50 to 90 mole % of fumaric acid and (B) a glycol component containing at least 90 mole % of ethylene glycol, trimethylene glycol, neopentyl glycol, hydrogenated bisphenol A or 2,2-d-(4-hydroxypropoxyphenyl)propane.

Resin composition for bonding foundry sand

In preparing a resin coated sand for use in sand mold casting processes by a hot-melt process using an unsaturated polyester which is solid at room temperature as the coating material, a solution of an organic peroxide as a polymerization initiator for the unsaturated polyester is introduced into the mixture of heated foundary sand and the unsaturated polyester while the polyester is in the state of liquid coating on the sand particles, and stirring is continued to uniformly mix the solution with the unsaturated polyester and evaporate and dissipate the solvent before solidification of the polyester coating as the result of cooling of the mixture. The polyester coating contains no liquid cross-linking agent, so that the resin coated sand is untacky and high in fluidity at room temperature and, therefore, can be filled into a die cavity to shape a sand mold or core with sufficiently high bulk density.

Method of preparing resin coated foundry sand using unsaturated polyester

Resin coated foundry sand, using a binder composition comprising 100 parts by weight of a crystalline unsaturated polyester and, as a cross-linking agent, 5 to 30 parts by weight of diallyl phthalate monomer. The binder is a scarcely tacky solid at room temperature but at a temperature somewhat above its softening temperature assumes a fluid state and exhibits a viscosity below about 500 poises. The resin coated sand is prepared by mixing heated foundry sand with the binder composition, with the addition of an organic peroxide which serves as a curing catalyst. Moulds and cores formed of this resin coated sand are high in initial strength but, nevertheless, can easily be disintegrated at the shake-off stage even when a relatively low pouring temperature is employed as in an aluminum alloy casting process.

Resin coated foundry sand using crystalline unsaturated polyester as

A crystalline unsaturated polyester composition for binding foundry sand, said composition comprising:

A binder composition for binding foundry sand particles to form molds and cores in sand mold casting processes which may be aluminum alloy casting processes, comprising a thermosetting resin and powdery zinc carbonate which is dispersed in the resin and, while the molds and cores are heated by the poured molten metal, undergoes thermal decomposition with generation of carbon dioxide gas which aids the molds and cores to become readily disintegratable.

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Yokohama, Japan

Koue Ohkawa