From milk powder cans to aerosol cans, how do metal packaging coatings meet the unique needs of different packaging types?

Publish Time: 2025-09-25

In the modern packaging industry, metal containers are widely used in a variety of applications, including food, beverages, pharmaceuticals, cosmetics, and chemical products, due to their high strength, excellent sealing properties, and superior barrier properties. From everyday milk powder and beverage cans to pressurized containers like pesticide cans and aerosol cans, metal packaging for different purposes places distinct demands on material properties. As the "protective barrier" between the inner and outer walls of metal cans, metal packaging coatings are the core technology that achieves these differentiated functions. They must not only prevent corrosion and ensure the safety of the contents, but also adapt to complex processing and extreme operating environments.

1. Milk Powder Cans: Safe and Non-Toxic, Moisture-Proof, and Protecting Nutritional Quality

Infant formula milk powder has extremely stringent packaging cleanliness and safety requirements. Milk powder cans are typically tinplate three-piece or two-piece cans, and the interior must be coated with a food-grade, non-toxic, and non-migrating coating. This type of coating typically utilizes epoxy phenolic resin or acrylic systems to ensure it does not react with milk powder and release harmful substances during storage at room temperature. Furthermore, the coating must possess excellent moisture resistance and oxygen barrier properties to prevent moisture absorption, caking, and oxidation-induced deterioration of the milk powder. Exterior coatings require high adhesion and scratch resistance, complemented by exquisite color printing to enhance the product's appearance. Furthermore, the coating must withstand the mechanical stress of the seam-sealing process to prevent cracking at the seal, leading to seal failure.

2. Beverage Cans: Sterilization and Corrosion Resistance to Maintain a Pure Taste

Liquid contents such as carbonated beverages, beer, and juice are highly corrosive to the interior of metal cans. Acidic beverages, in particular, can easily corrode the can and generate hydrogen, resulting in "can bulging." Therefore, interior coatings for beverage cans must possess strong resistance to acid and electrolytic corrosion. Modified epoxy resins or polyester coatings are commonly used to form a dense protective film that isolates the contents from the metal. After filling, beverage cans undergo high-temperature sterilization. The coating must possess excellent heat resistance and adhesion, resisting softening, blistering, and flaking in hot and humid environments above 90°C. Furthermore, the interior coating must inhibit the leaching of metal ions to avoid affecting the color and taste of the beverage.

3. Aerosol Cans: Pressure and Solvent Resistance for Safe Use

Aerosol cans are one of the most technically demanding types of metal packaging. The interior coating of aerosol cans must possess excellent resistance to organic solvents to prevent the propellant and contents from dissolving or swelling the coating. Furthermore, the coating must be highly flexible to accommodate the slight deformations of the can under high pressure, preventing cracking and leaks. Furthermore, the coating must provide excellent electrical insulation to prevent electrochemical corrosion and pass rigorous burst pressure and drop tests to ensure safe use.

4. Chemical and Paint Cans: Chemical Resistance and Durable Stability

Metal cans used to package chemical products such as paints, lubricants, and detergents often come into contact with strong solvents, alkaline, and acidic substances. Internal coatings typically utilize phenolic resins, modified epoxies, or fluorocarbon coatings. These coatings are highly chemically inert and resistant to benzene, ketone, and ester solvents, preventing corrosion and contamination of the cans. These coatings also require high hardness and abrasion resistance to withstand external impacts during transportation and stacking.

From ensuring food safety for milk powder cans, to preserving and preserving beverage cans, to ensuring pressure and solvent resistance for aerosol cans, metal packaging coatings precisely address the specific needs of various packaging types through customized resin systems, optimized functional additives, and controlled coating processes. They serve not only as a protective shield for metal cans but also as a key technology for ensuring product quality, extending shelf life, and enhancing brand value.