| 摘要 |
A process for making foundry cores and molds is disclosed as well as the core and molds which are produced as well as a sand binder. The binder is a resin which includes a lignin dissolved in a suitable solvent reacted and/or cured with an isocyanate material. The lignin used contains no more than 2% sodium ions. A polyether polyol may be added which has a functionality of greater than 3 and preferably at least 6. A tin catalyst is disclosed for use in the system which has a valence of +4 and one soluble in the system. A material is added to the system to give the mold or core a resistance to the water in core and mold washes. Suitable materials are propylene oxide derivatives of bis phenol A. |
