New Precoated Steel Sheet Excels in Hardness and Formability
NKK's new precoated steel sheet will be used for refrigerators and vending machine display panels like the ones pictured here.
NKK has begun marketing a newly developed precoated steel sheet that offers both excellent coating hardness and formability. Called "Excel Coat Geo-Flex" (GFX), the sheet is designed for refrigerators, air conditioners, and other home electric appliances. With more and more emphasis on ecological friendliness and economy, home electric appliance makers are increasingly adopting precoated steel sheets, rather than postcoating the sheets by themselves after forming. However, with conventional precoated steel sheets, lack of hardness has been a problem, because precoating has been applied flexibly, assuming that the sheets will be formed after coating. NKK has overcome this problem by applying a unique overcoating film to the sheet. The proprietary overcoating film contains a basic polyester resin added by special organic compound (oligomer) in optimum balance. This has resulted in the sheet's excellent flexing characteristics without film cracking at normal temperature. Moreover, its resistance to scratching makes the sheet the world's first to attain pencil hardness of the H level. With conventional precoated steel sheets, hardness has been limited to the HB level. GFX's excellent film coating hardness allows electric appliance makers to roll-form and pressform the sheet without scratching, thereby greatly improving handling and productivity. Because the sheet does not scratch even when bent, products can be designed freely to include curved lines. Also, the sheet can be employed as an environment-friendly product, since its film contains fewer solvent ingredients than conventional products. NKK has applied for about 20 patents on its new coating technology. GFX is available in thickness of 0.25-1.6mm with width of 610-1,250mm and is compatible with white, plain, and dark colors with a range of gloss. The price does not differ substantially from conventional precoated steel sheets. NKK intends to expand production of the new precoated steel sheet, making a gradual shift from the conventional postcoating method. |
