Research On CO₂-Cured Alkaline Resol Phenol-Formaldehyde Resin And The Cured Mechanism For Foundry

The new type cold-box technique of CO₂-cured Alkaline Resol phenolc resin is put forward by English Foseco Company in 1989 , which has many advantageous properties, such as low poisonous content (free phenoKO. 2%, free formaldehyde<0.1%), low environment pollution, simple curing process, and high production efficiency, etc. The resin sand is better than sodium polyarcylate and sodium silicate sand in strengthen at high temperature and humidity. It brings the benefit of environment protect and technology for foundry for the first time, and many experts at home and abroad pay more attention to it for its excellent qualities. The experiments are done from the four main parts as follow: (1) First, the reaction conditions which affect the synthesis of phenolic resin are discussed by orthogonal and single factor experiments, and the optimum conditions are obtained. The reaction process and structure are analyzed theoretically and the structure is characterized by FTIR. (2) On the basis of the optimum synthesis conditions, the techniques of the CO₂-cured phenolic resin for cold-box are researched. (3) The coordination reactions between the borax and phenol-formaldehyde resin are studied by the PH measurement of the solution, and the structure of the complexes and cured mechanism process are deduced. The structure of the resin and complexes is characterized by FTIR and DSC. (4) At last, the technique of phenolic resin modified by nano-SiO₂ and tung oil is elementarily discussed. The surface modification and dispersion of nano- SiO₂ particles with polyethylene glycol (PEG) is studied by FTIR and TEM, and the reaction mechanism of tung oil and phenol compound is discussed.