Materials for Can Lid

Materials for Can Lid

The raw materials for can lid include tinplate with inner and outer coatings and sealing adhesive.

1. Tinplate: The tinplate used for beverage tops and bottoms is mainly 0.20mm T4-CA iron. The dimensions of the tinplate depend on the type of cap, with common sizes including D200 (50mm), D202 (52.3mm), and D209 (62.4mm). Each company selects different widths and lengths of tinplate based on layout sizes, with the commonly used tin plating weight being 2.8/2.8g/m². There are also options for 0.20mm thick chrome-plated iron, with a minimum average chromium layer quality of 30mg/m². Aluminum sheets, commonly 5052-H19, are also used as materials for beverage can bottoms, though they are less common due to higher costs. As metal packaging materials are prone to corrosion, they generally require inner and outer coatings for protection.

2. Sealing Adhesive: To enhance the sealing performance of food cans, fluid sealing materials are usually applied in the grooves of the can lids, forming an elastic film with good adhesion to metal after drying. This film not only effectively seals gaps but also provides corrosion resistance.

   The sealing adhesive mainly comes in three types: water-based (latex), solvent-based, and thermoplastic. The requirements for sealing adhesives used in food packaging containers include:

   - a. Free from harmful substances, with stable chemical properties and good aging resistance;

   - b. Certain fluidity and stable viscosity for easy application;

   - c. Good adhesion to metal, capable of withstanding impacts and vibrations during processing and transportation;

   - d. Certain resistance to high temperatures.