The Research On Process And Materials Of CO₂-cured Alkaline Phenol-Formaldehyde Resin

The new type cold-box technique of CO₂-cured Alkaline Resol phenol resin is putforward by English Foseco Company in 1989, which has many advantageous properties, suchas low poisonous content (free phenol＜0.2%, free formaldehyde＜0.1%), low environmentpollution, simple curing process, and high production efficiency etc. The resin sand is betterthan sodium polyarcylate and sodium silicate sand in strengthen at high temperature andhumidity. It brings the benefit of environment protect and technology for foundry for the firsttime, and many experts at home and abroad pay more attention to it for its excellent properties.The experiments are done from the four main parts as follow: (1) First, the reaction conditionswhich affect the synthesis of phenolic resin are discussed by orthogonal and single factorexperiments, and the optimum conditions are obtained: the catalyst is LiOH,catalyst/phenol=0.2/1 (mole-ratio), phenol/formaldehyde=1/2.0 (mole-ratio), the reaction timeis controlled by the viscosity of resin, the viscosity of resin is 35s. Formaldehyde is added bymeans of dropping. (2) On the basis of the optimum synthesis conditions, the techniques ofthe CO₂-cured phenolic resin for cross-linking agent are researched, in this system of resin anewtype cross-linking agent is introduced, the single factor experiments of the dispersantagent, R salt, silane, modifying agent and other factors in this kind of cementing agent systemare done according to the measurement of compressive strength of resin sand core, then theoptimum content of all factors is confirmed. The result show: when resin content is 3.0%,alkali content is 20%, cured agent content R salt is 20%～22%, and coupling agent content is0.8%, the strength of sand core is highest. The influence of CO₂ blowing time and blow rateand humidity and keeping time of sand core etc on compressive strength of sand core arediscussed further. The results show: when the blowing time is 100s and the blow rate is0.65m³/h, the strength is higher. Humidity and keeping time of sand core have small influenceon the strength of sand core. The research on phenol formaldehyde resin which modified byacrylic acid, acid anhydride etc are done. (3) The cured mechanism of phenol formaldehyderesin is analyzed in theory. (4) The usage time, gas-forming property, adding content and other properties of the CO₂-cured phenolic resin are researched. (5) Through the marketresearch, and we also make the economical efficiency about the CO₂ hardened alkaline phenolformaldehyde resin binder, the result shows that it has a extensive popularization of space ascasting and it is feasible to apply to production practices.