Introduction to Tinplate

We mainly focus on stainless steel barrels and accessories. Today, we will introduce the material of metal waterproof cover, tinplate.

Tinplate, also known as SPTE, is a cold-rolled thin steel plate with a thin layer of metal tin on its surface. It has a certain strength and hardness, good formability and easy welding, and the tin layer is non-toxic and odorless, with a bright surface. Tin mainly acts to prevent corrosion and rust. It is a steel product with a thin stamped steel plate as the base and tin plated on its surface, with multiple layers of protective film. It has the characteristics of corrosion resistance, non-toxicity, odorlessness, surface gloss, light weight, high strength (compared to paper, wood, composite materials), easy printing, welding, processing and shaping, and strong adaptability to environmental temperature. Therefore, more than 70% of the total production of tinplate is used for food and beverage packaging.

The main characteristic of tinplate is the dual performance of electrochemical cathode and anode protection of its tin layer. That is, in the inner wall of a food can with a complex mixture (or weak acid electrolyte) and a certain vacuum, the potential of the tinplate layer is lower than that of the iron base material. The tin is anode, and its dissolution protects the iron. During the effective period of the food can, the dissolution of tin is basically harmless to the human body. On the outer wall of the can in the atmosphere electrolyte, the tinplate layer also exhibits cathodic protection, with sufficient chemical stability, which is incomparable to other can making materials.

There are two production methods: hot dipping and electroplating. The hot-dipping method has a thicker and uneven tinplate layer, and the thickness of the coating is difficult to control. It consumes more tin and has low efficiency, so its application is limited and gradually replaced by electroplating. Electroplating uses electroplating technology to uniformly plate the steel plate substrate with tin film. It has high productivity, low cost, thin and uniform coating, and can produce different thicknesses of coating. It can also be single-sided or double-sided plating. The main electroplating methods are alkaline electroplating, sulfate electroplating, halogen electroplating, and borofluoric acid electroplating.