• Protection of containers

The metal material of the can body of a three piece tin can is tin, and the metal materials of the top and bottom covers can be tin, plated iron, or aluminum. Except for aluminum, which does not rust, both tin and plated iron will rust when exposed to humid environments, especially when the coating layer and coating layer are damaged during processing, storage, and transportation; Moreover, different foods contain different corrosion factors, and their ability to corrode aluminum, tinplate, and plated iron far exceeds that of water. The use of coatings can isolate metal materials from contact with the outside world, avoiding scratches on the metal substrate Prevent the corrosion of substrates by corrosive factors in food.

• Decoration and brand promotion

Decoration and brand promotion are mainly aimed at the coating on the outside of cans. With the improvement of people's living standards, materials are becoming more and more abundant, and there are many varieties of food inside cans, and there are also many products of the same type. While people pay attention to the food inside cans, they are also paying more attention to the appearance quality of cans. Paper labels or anti rust coatings on the outside of cans have gradually been replaced by exquisite design and printing, highlighting personalized needs and brand charm.

• Food preservation

If there is no coating to prevent the corrosion factors in food from corroding the substrate, the metals in the substrate will gradually transform into tin ions, iron ions, or aluminum ions that enter the food, affecting the flavor of the food and seriously leading to non-compliance with relevant food hygiene standards.

• Assist in the processing and shaping of coating iron

With the development of modern processing technology, the speed of can making and lid making is getting faster and faster. Coatings play a crucial role in this process. It is the smoothness, hardness, and ductility provided by coatings that protect the substrate and enable the entire production line to flow quickly and smoothly.

• Good economic benefits

Before the use of coatings, food packaging used high tin deficient tinplate to prevent rust and protect food. Tin is a non renewable resource and is very expensive. The development of low-cost tinplate has solved some packaging problems for food. The development of coatings and the improvement of tinplate technology have made it possible to use low damage tinplate to package food, thereby reducing packaging costs.

* Requirements for coatings

• Good storage stability；

• The solvents in the paint pose little harm to human health；

• The inner coating used for canned food should comply with relevant national hygiene standards；

• Easy to construct, simple to operate, and forms a good coating after baking and curing；

• After the coating film is formed, it should have the required adhesion,；hardness, impact resistance, chemical resistance, density, and welding resistance together with the substrate to meet the process requirements of canning and capping；

• After canning and sterilization cooling, the coating should have a good appearance and no peeling off；

• The inner coating should not affect the flavor and color of the food；

• The inner coating, together with the substrate, should effectively prevent corrosion of the contents.