Study on PVA Modified Phenolic Waterborne Binder for Casting

Author of the article:DAN Siyuan, ZHANG Jianjun, MA Sude

Author's Workplace：School of Materials Science and Engineering, Xi Hua University, Chengdu 610039, China

Key Words：aqueous binder; phenolic resin; urea formaldehyde resin; polyvinyl alcohol

Abstract：The traditional oil soluble casting adhesive has poor environmental protection and collapsibility, which is not conducive to the reuse of molding sand and will affect the quality of castings. With polyvinyl alcohol (PVA), phenol, formaldehyde and urea as basic raw materials, water-based resin samples were prepared by the alkali-acid-alkali three-step method and used as casting adhesives. The resin samples were analysed by infrared spectroscopy and thermogravimetry, and their basic properties were tested. The results show that the tensile strength of molding sand made up of water-based adhesive prepared by esterification reaction and polycondensation reaction can reach 2.24 MPa, and increase with increasing resin addition. The collapsibility (500 ℃Vs 600 ℃) and gas generation (1.3 mL/g Vs 2.4 mL/g) of the water-based adhesiveare better than those of phenolic resin. There is no obvious pungent odor during use. Moreover, the molding sand can be treated by a wet method to remove the binder after use, reducing pollution to the environment. The product is expected to be used as a new type of water-based adhesive in casting.