Study on synthesis and properties of modified starch binder for foundry

In this paper, modified starch binder was synthesized using a new dry method with the aid of the compound catalysis of methanol and sodium hydroxide. The effects of various factors on the properties of the binder and its bonded core sand were discussed. The results have shown that granular carboxymethyl starch (CMS) with suitable degree of substitution (DS = 0.3–0.5) can be obtained by making cornstarch be carboxymethylated using this method. The modified starch binder has suitable viscosity and higher specific bonding strength as compared with native starch; besides, the binder bonded core sand has excellent comprehensive property and can partially replace synthetic resin binder bonded sand.