Food packaging inner wall coating preferred epoxy resin

With the expansion of the definition of food safety, countries are increasingly demanding food and agricultural product packaging. In the international market, many foods and agricultural products are packed in steel drums, and the hygienic requirements for the paint on the inner wall have attracted wide attention from all countries. According to experts from the China Epoxy Resin Industry Association, as early as the 1950s, the US FDA required a high degree of attention to the inspection of food and agricultural packaging drums. In order to meet the needs of the international market, China has also made specific provisions on the sanitary requirements for the coating of the inner wall of export food and agricultural product packaging barrels. According to the regulations, the food grade coatings allowed on the inner wall of the drum are: polyamide epoxy resin coating, and peroxyethylene coating and organic fluorine coating.

At present, the inner coated steel drums used in China for food and agricultural products generally include: honey buckets, juice buckets and ketchup buckets. If the inner coating drum used to hold these foods does not meet the safety food hygiene requirements of the inner wall coating, it will cause secondary pollution to the food, thus affecting the inherent quality of the product. According to experts from the China Epoxy Resin Industry Association, polyamide epoxy resin coatings are epoxy resin coatings, and epoxy resin coatings are also curing film coatings. Epoxy resin is generally formed by polymerization of bisphenol A (diphenolyl propane) and epichlorohydrin. The molecular weight of epoxy resin varies according to the degree of polymerization. From the hygienic point of view, the larger the molecular weight, the smaller the epoxy value. The more stable, the less prone to the migration of harmful substances into the food, so the safety is higher. As a curing agent for polyamide epoxy resin coatings, polyamide itself is a polymer compound, and no toxicity has been reported. The epoxy resin of the quality of the polyamide epoxy resin is closely related to the ratio of the curing agent and the degree of curing. The proper ratio of curing agent and the higher the degree of curing, the less uncured material in the epoxy resin coating that migrates into the food. According to the provisions of GB9686-88 "Sanitary Standard for Polyamide Epoxy Resin Coatings on Inner Walls of Food Containers", the evaporation residue of polyamide epoxy resin coatings in various solvents should be controlled below 30 mg/L.

The perchloroethylene coating is made of perchloroethylene resin as a raw material, and is mixed with a plasticizer. After being coated or sprayed, the inner wall of the drum is naturally dried to form a film. Perchloroethylene coatings are generally classified into primers and topcoats. The perchloroethylene resin contains a vinyl chloride monomer, which is a carcinogenic toxic compound. The perchloroethylene coating after film formation may still contain residual vinyl chloride. According to GB7105-86 "Sanitary Standard for Perfluoroethylene Inner Wall Coatings for Food Containers", the residual vinyl chloride monomer in the perchloroethylene coating after film formation should be controlled. 1 mg / kg or less. Organic fluorine coatings include polyvinyl fluoride, polytetrafluoroethylene and polyhexafluoropropylene coatings. These coatings are polymerized with vinyl fluoride, tetrafluoroethylene and hexafluoropropylene as the main raw materials, and are coated with certain additives in the packaging drum. Inner wall surface. Organic fluorine coatings have the characteristics of anti-adhesion and corrosion resistance, but their acid resistance is poor, so it is widely used in the inner coating drum barrels containing honey.

In recent years, juices, ketchup and honey exported from China have often been returned to foreign countries due to excessive pesticide content. As a food packaging drum, the residual amount of the coating solvent on the inner wall should be as low as possible. Therefore, when producing packaging drums in food, it is necessary to ensure that the food packaging drums are clean and the residual harmful substances do not exceed the hygiene standards in accordance with food safety and hygiene requirements. Experts from the China Epoxy Resin Industry Association said that an interlocking supervision system should be formed. The enterprises that use the food packaging barrels should obtain the food safety and hygiene inspection report for the packaging barrels from the packaging barrel manufacturers; the packaging barrel manufacturers should supply the coating suppliers. Request a food safety and hygiene inspection report for interior coatings. At the same time, the relevant departments should also regularly supervise and inspect the food packaging barrels and issue inspection reports.