The bio-based cold box resin was synthesized by a one-step method with rosin

phenol

methanol and paraformaldehyde as raw materials

zinc acetate as a catalyst. The effects of the molar ratio of phenolic aldehyde

the reaction temperature

the amount of catalyst and rosin dosage on the performance of the products were investigated by testing the refractive index

viscosity

accommodation

and intensity of the product. The results indicate that the suitable synthesis conditions for the bio-based cold box resin are presented as follows: the molar ratio of phenol to paraformaldehyde of 1∶1.6

the reaction temperature of 110 ℃

the amount of catalyst of 0.2%

and the addition of rosin of 3%. Through the analysis of infrared

molecular mass distribution

strength and thermogravimetric data

the tensile strength of resin sand with bio-based cold core box resin addition is significantly increased with a proper improvement in thermal stability

gas evolution and breathability.