What are the functions of tinplate inner coating?
(-) Coating purpose and requirements
Tinned plate, chrome plated and aluminum alloy thin plate made of cans are susceptible to corrosion and cause the contents to deteriorate. Therefore, most food cans require coatings inside the cans. Different food cans have different coating requirements.
- Purpose of coating
(1) Protein-rich aquatic products, poultry and meat cans use anti-sulfur coatings to prevent sulfidation corrosion caused by thermal decomposition of proteins, such as vulcanization spots and iron sulfide.
(2) The acidic tomato sauce and pickled cucumber adopt acid-resistant paint to prevent acid corrosion of the cans and ensure that the canned food has a certain shelf life.
(3) Certain anthocyanin-containing fruits, such as strawberries, cherries, and bayberry, use general coating material to prevent anthocyanins from corroding cans and contents from fading due to tin reduction
(4) Steamed fish and luncheon meat are easy to stick to the cans. The coating containing anti-sticking agent makes the contents easy to pour out and keep the shape complete and beautiful.
(6) Canned beer coating material is (spraying after weaving) to eliminate pores and prevent iron ions from dissolving, which affects the flavor and transparency of beer.
- Coating requirements
(1) The coating should be non-toxic after film formation, without affecting the flavor and color of the contents.
(2) After the coating film is formed, it can effectively prevent the contents from corroding the cans.
(3) The coating has good adhesion after film formation, has the required hardness, punch resistance and solder heat resistance, etc., which can meet the requirements of can making process.
(4) After sterilization of the canned product, the coating film will not change color, soften and fall off.
(5) Convenient construction, simple operation, and a good coating film can be formed after drying.
(6) The coating material and solvent price are cheap.
(7) The coating material has good storage stability.