Study On The Influencing Factors And Diffusion Coefficient Of Migrants Of Metal Cans Coating

Diffusion coefficient is an important factor in the migration of chemicals from polymer materials to food(simulants), which reflects the diffusion of chemicals in polymer and food. Meanwhile, it is an important macro parameter that describes the transfer process of small molecule chemicals within the polymer. In recent years, the frequent occurrence of food safety incidents caused people's great concern about food safety issues. Therefore, strengthening the migration behavior study of harmful substances in food metal cans coating has vital significance in improving the safety of canned food.This paper uses high performance liquid chromatograph and fluorescence detector to establish an effective detection method for the harmful bisphenol substances(BPA, BADGE, BFDGE) of metal cans coating and carry out the study on the influencing factors and diffusion coefficient of migrants of metal cans coating. The research work and conclusions are as follows:(1) Testing the harmful substances(BPA, BADGE and BFDGE) in metal cans coating by the method of HPLC-FD, results showed that three kinds of harmful substances obtained good separation effect and the standard curve linear was good, the correlation coefficient R2 was greater than 0.999, the recovery in simulated fluid was between 88.96% and 96.49%, the relative standard deviation(RSD) was between 1.64% and 4.61%(n=5), which means the HPLC-FD method has good accuracy and higher precision; Through the experimental study of different simulation conditions on the influence of the harmful substances diffusion coefficient in metal cans coating, results showed that:(1)Temperature was a very important factor that affects the rate of diffusion, in the range of 5 ?~40 ?, the diffusion coefficient increases slowly while in the range of 40 ?~80 ?, the diffusion coefficient increases more;(2)Three kinds of harmful substances in metal cans coating had the largest diffusion coefficient in ethanol simulated fluid, followed by fat, the lowest was distilled water;(3)With the increase of immersion time, the migration rate of diffusion was significantly increase in ethanol simulated fluid, the diffusion coefficient of three kinds of harmful substances showed a gradually increasing trend.(2) Studying the influence of curing process on the diffusion coefficient of harmful substances in metal cans coating, results showed that: Curing temperature, curing thickness and curing time all had significant influence on the diffusion coefficient of harmful substances in metal cans coating, and the influence strength order is curing thickness>curing temperature>curing time. The optimal parameters when the diffusion coefficient of BPA and BADGE in metal cans coating had the minimum value after optimized by response surface method were: BPA: curing temperature A=202.22 ?, curing thickness B=9.73 g/m2, curing time C=12.89 min; BADGE: curing temperature A=203.68 ?, curing thickness B=9.27 g/m2, curing time C=12.77 min. The results of verification experiments of curing process parameters that adjusted in accordance with the actual experiment were very close to the theoretical predictions value, indicating that the optimal curing process parameters of the response surface method was accurate and reliable.(3) Testing the coating performance of metal cans under different curing process parameters, results showed that: Coating thickness, coating hardness, coating adhesion and coating scratch resistance all had a certain influence on the diffusion behavior of harmful substances in metals cans coating, considering the samples' coating hardness, adhesion and scratch resistance under different curing process parameters, initially selected the optimum curing process parameters: curing temperature 200 ?, curing thickness 10 g/m2, curing time 12min; Using Image Pro Plus software to analyze the SEM images of samples with different curing thickness, curing time and got the optimal curing process parameters: curing thickness 10g/m2 and curing time 12 min, and the analysis results had an effective verification on the migration experiment and response surface analysis results, meanwhile, had a very good explanation for the effects of metal cans coating structure on the diffusion coefficient.