Study On Two-component CO₂-hardened Alkaline Phenolic Resin Binder

In the traditional casting process,triethylamine process is usually used.Triethylamine is toxic,harmful and easy to pollute the environment.Therefore,the research and development of new efficient and environmental protection cold box core making process is the urgent demand of green casting production.The CO₂ gas is nontoxic,tasteless and environmentally friendly.In this thesis,the preparation technology and hardening mechanism of two-component CO₂ hardening basic phenolic resin binder are studied.First of all,the basic synthesis process of phenolic resin was determined through exploratory test:A certain amount of phenol and formaldehyde were added into the three ports flask and stirred.Add a certain amount of NaOH catalyst,heat and slowly raise the temperature of the material to 90?,conduct heat preservation reaction for 20-30 minutes,cool the material to 50?,put a certain amount of KOH into a three port flask,then raise the temperature of the material to 95?,conduct heat preservation reaction to a viscosity of 20s-22s,and cool it to room temperature for standby.Then,a single factor test was carried out for the factors such as the ratio of phenol to formaldehyde,the ratio of phenol to sodium hydroxide,the holding time,the type and amount of catalyst,etc.,and the main influencing factors and levels were determined.The optimum synthesis technology of phenolic resin was determined by orthogonal test.Phenol:formaldehyde=1.0:2.2,phenol:KOH=1.0:0.8,phenol:NaOH=1.0:0.08,90?holding the reaction time was 25 minutes.Next,the composition I of CO₂ hardening basic phenolic resin binder was optimized,in which KOH was used as dispersant,borax as crosslinking agent,silane as coupling agent,tensile strength as main inspection index.The components of the binder were optimized by orthogonal test,and the optimized ratio was that phenolic resin body:KOH:borax:silane:agent A=100:24:15.2:1:8.4.The immediate strength is 0.38MPa,and the 24-hour tensile strength is 0.60MPa.In addition,adding organic active agent C to the binder,the initial strength can reach more than 0.40MPa,the final strength can reach more than 0.96MPa,and the best adding amount of agent C is 12%.In this thesis,the composition of CO₂ hardening phenolic resin binder II-powder hardener was studied.Taking the tensile strength as the main index,the optimal ratio of the hardener is that micro silica powder:aluminate cement=1:1,and the effect is the best when the amount of hardener is 30%of the resin.The initial strength can reach 0.63MPa,and the final strength can reach 1.4MPa.Finally,the production verification is carried out.The prepared sand core has high strength,fast hardening speed and good collapsibility,which can meet the requirements of casting production.