Via Google kwam ik wel op iemand met ongeveer eenzelfde vraag:
I have been trying to find out what coating is used inside the soda cans which prevent the liquid from reacting with the aluminum (soda cans are made of aluminum).
Also, once that is identified i need to find a chemical that could be used to remove the coating. The goal is to obtain the aluminum without the coating.
Note: i do not have enough chemistry background so it will be extremely helpful to get as detailed info. as possible.
I am answering your question but you may not understand some of the chemical aspects. Interior can coatings designed to prevent migration of metal salts into the contained product are called "comestible polymeric coatings". The coatings ars polymers typically used in coil coating. The exact nature of the coatings isn't available since most are proprietary to manufacturers who continuously look for better coatings.
Most are epichorohydrin - bisphenol A epoxy;s cross-linked with urea-formaldhyde or vinyl resins or other materials. These polymers are used because of the good adhesion to the can metal and because of the very low extractables from the polymers.
Removing the polymer isn't an easy task. Recyclers handle this by incineration which is an energy intensive process. There are some patents looking at biodegradation of the polymer. The process is not simple and requires hours to remove the polymer. Solvents that could dissolve the polymer are things like tetrahydrofuran (THF) or ortho-dichlorobenene. A solvent based process will have a lot of environmental concerns. The need for the aluminum in the cans will have to economically support the cost of the process. There is a large recycling industry because the cost of the aluminum is less than that of aluminum from ore. It takes about 30, 12 oz. beverage cans to provide 1 lb of aluminum.
- Bill Choate