Research On Furan Resin Binder Material And Technology Of Warm Box

Compared with the traditional hot core box method,the warm core box method has the characteristics of low core box temperature,small on-site odor,small gas evolution of core sand,accurate core size,etc.,which is conducive to environmental protection and energy saving and emission reduction.To developed the warm core box method on the materials and processes have certain theoretical research significance and practical application value.In this article mainly focuses on the synthesis process of the warm core box furan resin,the modification process of the resin and the preparation process of the composite curing agent.In this paper,some single factor exploratory experiment were carried out on the basic synthesis process of the warm core box furan resin.Afther that,an orthogonal experiment was carried out to obtain the optimal synthesis process parameters of the warm core box furan resin as followed:the molar ratio of phenolic:formaldehyde was 1:2.5,and furfuryl alcohol was added 65%.In the alkaline reaction stage,the temperature was 90?,the pH value was 8.0,and the reaction time was 60 minutes.The temperature in the acidic reaction stage was 95?,the pH value was 4.0,and the reaction time was 60 minutes.The free formaldehyde content of the resin was 0.90%,and the viscosity was 32.5m Pa·s.The problem of high free formaldehyde content in resin was needed to be improved.Two materials,urea and cardanol,were selected for aldehyde reduction treatment.Urea could be added in the early,acidic and late stages of the alkaline reaction.The amount of addition was about 6%,to reduce the free formaldehyde content of the resin to less than 0.3%;the effect of cardanol was better when it was added in the early stage of the alkaline reaction and the acidic reaction stage.The addition amount was about 8%,to reduce the free formaldehyde below0.24%.The curing agent used in the warm core box furan resin is generally a latent curing agent,which is neutral or weakly acidic at room temperature.When it is heated,it releases a large amount of H~+to cure the resin.In this paper,a special phosphate and metal salt were selected for compounding,in which the phosphate accounted for 70%and the metal salt accounted for30%of the curing agent.The preparation process of phosphate was optimized by an orthogonal experiment.When phosphoric acid was 75g,water was 25g,aluminum hydroxide was 10g,magnesium oxide was 2g,and boric acid was 3g,the curing effect of phosphate was best.Ferric chloride and magnesium chloride were selected through the experiment of composite metal salt,and the effect was better when ferric chloride:magnesium chloride=1:1.The process performance of the furan resin and composite curing agent of the warm core box was tested.The temperature of the core box was 180?,the heating time was 60s,the resin content was 1.5%to the original sand,the curing agent was 40%to the resin,and the resin's instant tensile strength The strength was 0.57MPa,the normal temperature tensile strength was2.34MPa,and the 24h tensile strength was 2.14MPa.The molding sand had a good collapsing performance,the gas evolution was 11.3ml/g,and the workablr time is more than 6h.All performance indicators had been reached which can meet the actual production requirements.