Epoxy zinc-rich primer is a commonly used heavy-duty anti-corrosion primer. There are three standard zinc content levels on the market: 60%, 70%, and 80%. These three levels are specified by the Chinese national standard. In addition to the Chinese national standard, there are many other customized paints with different zinc content in the market to meet the specific needs of customers. The specific zinc content varies because the zinc content has a significant impact on corrosion prevention. Now let's understand the relationship between the zinc content of epoxy zinc-rich primer and its anti-corrosion service life.
Firstly, it is well-known that the excellent chemical resistance of epoxy zinc-rich primer is due to the cathodic protection provided by zinc powder. It can form a dense oxide layer on the surface of the substrate, thereby blocking the penetration of corrosive substances and other media into the substrate.
The higher zinc content specified by the national standard is to ensure the protective capability of zinc powder.
In severely corrosive environments, if the zinc content is insufficient, the overall protective layer on the substrate will appear thin, and the protective effect of zinc powder cannot cover the surface of the item, weakening the corrosion resistance of epoxy zinc-rich primer and unable to guarantee the service life of corrosion prevention.
Therefore, a certain high zinc content is a necessary requirement to ensure the service life of epoxy zinc-rich primer.
However, higher zinc content is not necessarily better. Firstly, in the zinc powder layer of traditional epoxy zinc-rich primer, only 30% of the actual coating plays the role of cathodic protection.
Furthermore, if the zinc content is too high, the resin content in the zinc-rich primer will decrease, the film-forming substance will reduce, and the final film formed will be thin with poor adhesion, unable to bond well to the substrate. This can lead to problems such as film peeling or even detachment.
Excessive zinc content can easily react with water and other media, causing corrosion of zinc, resulting in blistering of the film and reducing the service life of corrosion prevention.
The zinc content of epoxy zinc-rich primer is related to the service life of corrosion prevention, but it should not be too low or too high. Following the national standard is sufficient.
Tianjin Jinhai Special Coatings & Decoration Co., Ltd. is a high-tech paint and coating manufacturer and developer that integrates production, training, and research. We have obtained the ISO9001 quality management system certification and CCS factory certification from the China Classification Society. Feel free to contact us for inquiries.
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