The production of can lids involves key raw materials such as tinplate with inner and outer coatings, and sealing adhesives.

1. Tinplate

Tinplate used for beverage tops and bottoms is primarily 0.20mm T4-CA iron. The dimensions vary depending on the type of cap, commonly including:

• D200 (50mm)
• D202 (52.3mm)
• D209 (62.4mm)

Each company selects different widths and lengths of tinplate based on layout sizes, with the commonly used tin plating weight being 2.8/2.8 g/m². Alternatives include:

• Chrome-Plated Iron: 0.20mm thick with a minimum average chromium layer quality of 30 mg/m².
• Aluminum Sheets: Commonly 5052-H19, used less frequently 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 applied in the grooves of can lids. After drying, they form an elastic film with good adhesion to metal, effectively sealing gaps and providing corrosion resistance.

Types of Sealing Adhesives:

• Water-Based (Latex)
• Solvent-Based
• Thermoplastic

Requirements for Sealing Adhesives in Food Packaging Containers:

a. Safety and Stability: Free from harmful substances, with stable chemical properties and good aging resistance.

b. Applicability: Adequate fluidity and stable viscosity for easy application.

c. Adhesion and Durability: Good adhesion to metal, capable of withstanding impacts and vibrations during processing and transportation.

d. Thermal Resistance: Certain resistance to high temperatures.