| Furan resin is a kind of common binder for casting and molding core making.However,the free formaldehyde content in traditional furan resin is too high,which inevitably releases harmful gas during pouring,which has caused harm to the health of workers on site.At the same time,furfuryl alcohol,the main raw material for the synthesis of furan resin,is expensive,which also restricts the application of furan resin.In this paper,lignin and phenol B from plant extracted were introduced to modify the furan resin in the process of resin synthesis,to obtain a higher bond strength and reduce the odor and cost of furan resin.First of all,through some exploratory experiments,single factor experiments were carried out one by one to determine the basic synthesis process of urea formaldehyde molar ratio,alkali reaction temperature,time,p H value,acid reaction temperature,time and p H value,and the basic synthesis process was determined.Through two sets of orthogonal experiments,the optimized synthesis process was obtained.The main was as followed: formaldehyde,urea and furfuryl alcohol were put into a three port flask,the urea was dissolved,the p H value was adjusted to 9.0by sodium hydroxide solution.The temperature of the liquid was slowly raised to 85 ?,the time of alkaline reaction was recorded,and the reaction condition was maintained for 70 minutes.After that,furfuryl alcohol of the second step was added,the p H value was adjusted to 4.5,the temperature was slowly increased to 90 ?,and the reaction was kept for 60 minutes at 90 ?.The temperature was lowered to 80 ? for neutralization and dehydration.The dehydration amount was 60% of the added amount of formaldehyde,and then the furfuryl alcohol was added,stirred for 10 minutes,and cooled to room temperature.The 4 h tensile strength of resin sand was1.85 MPa,the 24 h tensile strength was 2.53 MPa,the free formaldehyde content was 0.35%,and the furfuryl alcohol content was 75%.Secondly,through experiments,the effects of aciddic lignin,lignin M,lignosulfonate lignin and alkali lignin on the properties of furan resin were discussed.It was found that the effect of lignin M on the properties of furan resin was better.Through the exploratory test,a good method of lignin modification which was lignin modified furfuryl alcohol method was determined,and the best process of lignin modification was determined: lignin content was 6%(accounted for total resin),modification time was 75 minutes,modification temperature was 100 ?,modification p H value was 8.5.The 24 h tensile strength of resin sand was 1.57 MPa,the content of free formaldehyde was 0%,the content of furfuryl alcohol was 70%,and the viscosity was44 m Pa·s.In view of the lowed strength in the modification test of furan resin with lignin,the phenol B from plant extracted,monosaccharide A and methanol were used as modifiers for compound modification to improve the tensile strength of the resin sand.At the same time,production costs can be further reduced.Through experiments,it was determined that the amount of modifier added accounted for 10% of the total resin.The amount of phenol B from plant extracted,monosaccharide A and methanol accounted for 4%,3% and 3% of the total amount of the resin respectively.The 4h tensile strength of the resin sand was 1.81 MPa,the 24 h tensile strength was2.18 MPa,the free aldehyde content was 0%,the furfuryl alcohol content was 60%,and the viscosity of resin was 46 m Pa·s.Finally,the process performance test and economic analysis of the resin were carried out,and the requirements of casting production can be meet. |
PDF Full Text Request