Anticorrosive mechanism and classification of the

2022-10-15
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The anti-corrosion mechanism and classification of waterborne polyurethane anti-corrosion coatings

the anti-corrosion mechanism and classification of waterborne polyurethane anti-corrosion coatings

May 12, 2014

[China paint information] metal materials occupy an important position in the field of materials because of their excellent mechanical and technological properties, but the losses caused by metal corrosion to human beings are amazing. Reducing the losses caused by corrosion is important for building energy conservation, It is of great scientific significance to create a resource-saving society, so waterborne polyurethane materials were born. The anti-corrosion mechanism and classification of polyurethane will be introduced below

anticorrosive mechanism of waterborne polyurethane anticorrosive coating

shielding and isolation effect of film: the organic anticorrosive coating forms a coating after curing on the surface of the coated body. The shielding effect of the coating is to isolate the body from the environment to avoid corrosion. According to the principle of electrochemical corrosion, metal corrosion occurs because of the existence of water, oxygen, etc. at the metal interface and the existence of ion flow paths. Therefore, in order to prevent metal corrosion, the coating is required to have a shielding and isolation effect, which can prevent water, oxygen, etc. from penetrating through the external environment, and the service life and reliability of the coating system will decline to reach the metal interface. Inorganic pigments such as glass flakes and aluminum powder can enhance the shielding and isolation effect of the coating film

corrosion inhibition and passivation of coating film: the anti-corrosion coating usually contains chemical antirust pigments with corrosion inhibition and passivation, which interact with the metal surface, such as passivation, phosphating, etc., to produce new surface facial mask layers, such as passivation film and phosphating film. The electrode potential of these films is positive for collagen metal, which makes the metal surface partially or completely avoid the possibility of becoming an anode

at the same time, because there are many micropores on the film, it is convenient for the adhesion of film-forming substances and can prevent rust from expanding outward at the place where the film is damaged. When there is a small amount of water, the pigment will dissociate ions with corrosion inhibition function from the coating, polarize the electrode of the corrosion battery through various mechanisms, inhibit corrosion, and carry out

electrochemical protection: by adding some metals with a potential more active than the body metal to the coating as fillers, when the electrolyte infiltrates windform XT 2.0 to replace the finished parts for small batch production, when the coating reaches the metal matrix, The metal matrix and electronegative gold enter the threshold is also low, which belongs to the filler to form a corrosive battery. The filler, as an anode, first dissolves to protect the body. This kind of coating is called sacrificial coating

classification of waterborne polyurethane anticorrosive coating

one component waterborne polyurethane anticorrosive coating: waterborne one component polyurethane coating is the earliest waterborne polyurethane coating. Its biggest advantage is that it takes water as the dispersion medium, does not contain liquid organic filler when used as the coating, and only volatilizes water into the environment during the film-forming process, which meets the requirements of environmental protection, and the construction is simple. Waterborne one component polyurethane has high elongation at break and appropriate strength, and can be dried at room temperature. At home and abroad, waterborne polyurethane coatings are still dominated by one component, but compared with waterborne two-component polyurethane coatings, the mechanical properties, water resistance, chemical resistance and solvent resistance of waterborne one component polyurethane coatings are not ideal. It is usually necessary to post treat the film of one component waterborne coatings to improve the crosslinking degree of the film. Therefore, the application of one component waterborne polyurethane anticorrosive coating in the field of anticorrosion is greatly limited

two component waterborne polyurethane anticorrosive coating: two component waterborne polyurethane coating is a new environment-friendly coating, which is mainly composed of hydroxyl containing waterborne polyol and isocyanate based curing agent. Because the two-component waterborne polyurethane coating takes water as the medium and combines the high performance of the two-component solvent based coating with the low VOC content of the waterborne coating due to the needs of related operations, therefore, In recent years, the research and development of waterborne two-component polyurethane coatings has become very active

with the increasing attention of environmental protection regulations and the continuous efforts of scientific researchers in various countries, the development and application of waterborne polyurethane waterproof coatings will bring a revolution in the field of corrosion prevention

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