Study On Modification Of Phenolic Resin For Casting

As a kind of binder for casting molding cores,resin has the characteristics of high strength,high dimensional accuracy,high hardening speed,high production efficiency,low labor intensity,etc.Currently,it has been widely used in casting process production.However,with the development of industrialization and the increasingly strict environmental protection,the environmental factors such as the large amount of flue gas and excessive pungent odor of the phenolic resin in the foundry industry have increasingly constrained the development of this resin sand industry.This item is commissioned by the company to modify the traditional phenolic resin process conditions,accelerators,raw material ratio,coupling agent type and addition amount of research and development of new types of new environmentally friendly high-strength,low-nitrogen,low smoke volume casting resin.The results showed that the molar ratio of phenolic can be synthesized under the premise of synthesizing thermoplastic phenolic resin.With the molar ratio of phenolic resin increasing,the polymerization speed of the resin was increased and the tensile strength was increased.The optimum phenolic molar ratio was 0.73.When the dosage of curing agent urotropine is 10%,the polymerization rate and tensile strength of the resin are the best.Increased curing temperature can increase the polymerization rate,the best curing temperature is 150 °C.Increase in the amount of curing agent can also accelerate the polymerization rate of phenolic resin,the best amount of 10%.The existence of a certain amount of phenol in the resin can increase the polymerization rate and tensile strength of the resin,and the comprehensive range of phenol content is preferably 2-2.5%.Four kinds of accelerators,adipic acid,citric acid,succinic acid and dimethylimidazole,can accelerate the polymerization rate of phenolic resin in different degrees,among which dimethyl imidazole has the best promoting effect on the resin.Increasing the amount of coupling agent can also accelerate the tensile strength of phenolic resin,of which the best KH-550,the best amount of 0.2%.The addition of calcium stearate has a significant effect on the tensile strength of the resin,and the best addition is 0.4%.Designed and developed a new resin process,the raw material ratio is:the amount of phenol added is 80% of formaldehyde,and the amount of decyl alcohol added is 1.3 times that of formaldehyde.Specific synthesis process:In the first alkaline reaction process,the heating temperature is 90°C,the reaction time is 30 minutes,and the reaction pH is 7.5.In the second step,during the acidic reaction,the heating temperature was 105°C,the acidic reaction time was 60 minutes,the acidic reaction pH was 4,and the dehydration amount was 55% of the solid formaldehyde addition amount.The performance of the new resin: smoke volume 12.04ml/g,thermal tensile strength 1.4MPa,normal temperature tensile strength 2.3MPa,free formaldehyde content 0.40%,resin nitrogen content 3.2%.Sorbitol,glycerol,and ethanol can all be used instead of decyl alcohol as a raw material.Considering the stability of the resin quality,sorbitol is the best substitute,and the substitution amount is 10%.From the standpoint of the stability of the resin production,glycerol is the best substitute and the substitution amount is 10%.From the viewpoint of industrial cost,ethanol is considered.As a substitute,the replacement amount is 5%.