Importance

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Abstract

A polyurethane system for use as a binder in producing foundry molds and cores in metal casting, especially in a “cold box” process, has a polyol component with one or more polyols having at least two OH groups per molecule, with at least one phenol resin, and an isocyanate component. Particularly, the isocyanate component includes a reaction product of at least one cyclic amine with at least one polyisocyanate having at least two NCO groups per molecule. Each cyclic amine is characterized as an amine having at least one NH— group and from four to six carbon atoms. Examples of the cyclic amine include ε-caprolactam and/or 3,5-dimethylpyrazole. Observed advantages include better humidity resistance and improved mold release properties.

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First Claim