What can be used for food drum packaging?
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Epoxy/polyamide coatings are epoxy resin coatings, while epoxy resin coatings are cured film forming coatings. According to experts, epoxy resins are generally made from the polymerization of bisphenol A (diphenol propane) and epichlorohydrin. When the degree of polymerization is different, the molecular weight of the epoxy resin is also different. From the viewpoint of safety, the larger the molecular weight (ie, the smaller the epoxy value) is, the more stable the harmful substance is, the more difficult it is to migrate into the food, and therefore the higher its safety.
As a curing agent for epoxy resin coatings, polyamide itself is a polymer compound, and no toxicity has been reported. The quality of polyamide-cured epoxy resins is closely related to the ratio of curing agents and degree of cure. The more appropriate the curing agent ratio, the higher the degree of cure, and the less uncured material in the epoxy resin coating will migrate into the food product. According to the provisions of GB9686-88 “Sanitary Standards for Polyamide Epoxy Resin Coatings on Inner Walls of Food Containersâ€, the evaporation residue of polyamide epoxy coatings in various solvents should be controlled below 30 mg/l.
Perchloroethylene paint uses vinyl chloride resin as raw material, together with plasticizer, and is naturally dried and filmed after being painted or spray-coated on the inner wall of the barrel. Perchloroethylene coatings are generally divided into primers and topcoats. Perchloroethylene resins contain vinyl chloride monomer, which is a carcinogenic and toxic compound, and the vinyl chloride coating after film formation may still contain residual vinyl chloride. According to the hygienic standard of the national food container vinylidene chloride inner wall paint, the residual vinyl chloride monomer should be controlled below the safety value in the film-forming vinyl chloride coating. The plasticizers, solvents, and other additives used in the perchloroethylene coatings must meet the national hygiene standards for the use of additives for food containers and packaging materials, and must not use toxic or highly toxic additives.
In addition, the organic fluorine coating is another coating that can be used on the inner wall of the food packaging barrel, and includes polyvinyl fluoride, polytetrafluoroethylene, and polyhexafluoropropylene coating. Organic fluorine coatings have the characteristics of anti-sticking and corrosion resistance, but their acid resistance is poor, so it is widely used in inner coating steel drums containing honey.
In terms of application, the organic fluorine coating on the inner coated honey drum is PTFE, which is abbreviated as PVF coating. It is a kind of macromolecular compound with stable chemical properties. Under normal circumstances, there will be no monomer residue. It is a relatively safe food packaging barrel wall coating. However, when cleaning the inner wall of steel drums, most of the production enterprises of the barrels are currently using spray washing and drying lines for cleaning. Chromate is commonly used for cleaning enamels, which may cause chromium salts to remain on the surface of the container and then mix in the paint. Therefore, in the production of honey coated steel drums, it should be in accordance with GB1167-89 "food container PTFE wall paint hygiene standards" on the inside of honey coated steel drum inspection, in the use of PTFE coated honey drums coated with PTFE The general baking temperature must not exceed 250°C.