Abstract: The CO2-cured alkaline phenol-aldehyde resin binder used in foundry is a new kind of binder system which is composed of specially synthesized alkaline phenol-aldehyde resin, alkali, borax and silane. According to the affection on the compressive strength of binder, the optimum results are achieved by the experiments of orthogonal design about the amounts of alkaline phenol-aldehyde resin, alkali, borax and silane to form a steady binder system with high compressive strength. The proportion of the above components is the alkaline phenol-aldehyde resin∶KOH∶Borax∶KH-550=100∶45∶16∶1, and the influence of KOH, borax to the compressive strength of binder is more remarkable. A few kind of materials such as alcohol, acetone and glycerin are added into the binder separately to test the influence of each one on the compressive strength of binder. It is found that two kinds of organic active agents with addition 5%, 15% to the binder can improve the strength of binder obviously. At last the higher initial strength above 1.5 MPa and final strength above 3.7 MPa can be achieved by optimization of the components and the behavior of bonding bridge fracture is analyzed by using scanning electron microscope. The organic active agents are believed to play an important role in cross-linking of resin and have great effect on the strength of binder.

Key words: Binder, CO2-cured phenol-formaldehyde resin, Organic active agents, Orthogonal design