Code spraying only proves the place, time or anti-counterfeiting mark of the product, but it can't prove that all products are good. Ink contains a lot of heavy metals (especially lead), which is harmful to human body and inedible.
Analysis:
1, eggshell structure: the eggshell can be divided into three layers, the outer layer is cuticle (hard shell), the middle layer is spongy, interwoven with calcium fibers, and the innermost layer is papillary layer. There are many small holes (about 7000) on the surface of the eggshell, through which air or microorganisms can enter the egg and the water in the egg can be discharged.
2. When the ink of the inkjet printer is printed on the eggshell, the diluent component will dry within 5 seconds, leaving the pigment on the eggshell, so the time for the ink to penetrate into the eggshell is 5 seconds.
3. Because the eggshell has three layers, and the pore size of the small hole is very small, the infiltration time is too short, and basically it will not really penetrate into the eggshell, so this concern can be ignored.
Extended data:
The main component of eggshell is calcium carbonate. The pores on its surface can exchange gas with the outside world, and ink will block the pores, but this has little effect. The most important thing is that ink molecules will penetrate into eggs, causing secondary pollution to eggs.
Organic solvents, such as ethanol, isopropanol, butanol, propanol, butanone, ethyl acetate, butyl acetate, toluene, xylene, etc. Usually used in ink. These chemicals are harmful to human body. In short, they are harmful to eyes, respiratory tract, liver, kidney and brain. Of course, a few eggs will not cause any impact, and long-term consumption will have adverse consequences on human health.
Baidu encyclopedia-eggshell
Baidu encyclopedia-eggshell spraying code