Organic Coating Method for Sheet Metals

For sheet metal containers with an iron structure, the styrene-diolefin coating composition, which has excellent coating properties, must be appropriately modified. Organic coating methods have been used on metal sheets for a very long time.

Coating methods have significant problems, especially in the production of tin cans. Tin cans must be resistant to deterioration during production and use.

Drawing and bending processes are performed while manufacturing tin cans. To achieve a continuous and smooth coating during these processes, the resulting coating material must have a flexible structure. It must also be resistant to chemical-based effects.

Therefore, it is necessary to develop an organic coating composition with optimum effects against potential corrosion occurrences.

Tin plating processes have been used in sheet metal production for a very long time. Due to tin plating in sheet manufacturing, tin consumption has reached record levels. Therefore, new methods must be researched to conserve tin in the coating composition and to change the coating compositions.

What is the Structure of Organic Coating?

In this organic coating, tin plating will be completely removed, and instead, corrosion prevention will be ensured solely through the organic coating method.

A copolymer is used in this method. The copolymer to be used is styrene-diolefin. The styrene-diolefin copolymer will be modified with a very small amount of acidic phosphorus compounds and applied onto the plate with an iron structure. This way, it will have excellent thinness, a hard structure, and flexible and adhesive properties.

In this way, the layer between the metal surface and the coating composition will be resistant to atmospheric properties and other chemical attacks.

Expected properties from the organic coating we obtain include color change, blistering, adhesion, and flexibility. During the development of these properties, adding a small amount of acidic phosphorus compound to the copolymer form occurs by the phosphorus compound preventing the oxidative polymerization of the cross-linking event during the curing of the resulting film.

What Are the Acidic Phosphorus Compounds Used in This Application?

The acidic phosphorus compounds used are as follows.

• Phosphoric Acid
• Orthophosphoric Acid
• Metaphosphoric Acid
• Phosphonic Acid
• Phosphorous Acid
• Pyrophosphoric Acid

As can be seen here, phosphorus compounds that can provide phosphoric acid in aqueous solutions are also used.

Why Are Sheet Metals Organically Coated?

Organic coating is the process of coating metal surfaces with various organic compounds. This coating process is used for various purposes such as ensuring the protection of metal surfaces, increasing corrosion resistance, enhancing mechanical durability, or improving electrical properties.