Research And Application Of CO₂ Air-hardened Cold Core Environmental Protection Resin

A new type of cold box core material with high efficiency,energy saving and environmental protection and its application in sand cores of cylinder block castings are studied.It has excellent technological properties and is suitable for mass production of green and environmental protection foundry.The following results have been achieved in this paper:?1?The bulk synthesis process of phenolic resin was optimized.The phenolic resin body with high strength was obtained by determining the optimum technological parameters and raw material ratio.The condensation reaction of formaldehyde and phenol was carried out with Na OH as catalyst under the action of alkaline catalyst.The technical parameters are as follows:Na OH concentration?mass fraction?is 0.06-0.08%,the molar ratio of phenol to formaldehyde is 1:2.0-2.5,the reaction time is controlled at 150 minutes,the end point is flexibly controlled by viscosity measurement,and the viscosity is controlled at 25-30mpa.s.?2?The technological conditions for the preparation of CO₂ pneumatic phenolic resin binder were optimized.The optimum experimental conditions were determined by orthogonal test,phenolic resin:KOH:borax:silane=100:45:16:1.The properties of the binder,the strength and stability of sand moulds?cores?and the fluidity of resin sand were improved by adding various active groups?catalysts,ether bonds containing cyclic ether alcohols,etc.?.?3?The mechanism of improving the properties of CO₂-hardened phenolic resin binder was studied.The technological parameters of resin addition,service time,collapsibility and gas emission of CO₂ hardened phenolic resin bonding sand were determined.The mechanism of blowing hardening of the bonding agent was studied by means of NMR,IR and SEM.?4?The pilot test and production application of binder preparation have been completed.The preparation process of phenolic resin binder was verified,and the optimum process parameters were optimized for the mass production of the binder.In a pilot plant of a company,several core-making production tests were carried out on site,and many gray iron cylinder castings were successfully poured.The core-making site is non-toxic and odorless.The prepared sand core has high strength,good collapsibility,easy cleaning and no casting defects.The air-hardened cold-box binder developed can meet the requirements of field casting production.Good economic,social and environmental benefits have been achieved in production and application.