Disadvantages of polyurethane powder coatings

2021-12-02   Pageview:143

The biggest disadvantage of polyurethane powder coatings is that when the film is cured in the oven, the sealer is released, causing pollution to the environment and atmosphere. In addition, when the coating film is too thick, pinholes or bubbles are easily produced due to the release of sealer. For this reason, the amount of sealer should be reduced as much as possible to lower the emission to the atmosphere, and non-toxic sealer should be considered at the same time.

 

 

 

 

 

 

 

 

 

 

 

 

 

The protection of metal materials by coatings can slow down corrosion through the following measures:
①Improve the adhesion between the coating and the substrate;
②Establish a barrier coating to reduce the penetration of water and oxygen into the metal substrate;
③Select active pigment systems and additives that have phosphating, passivation and corrosion inhibition effects on steel;
④Choose materials with lower electromotive force than iron, such as metal powders such as aluminum and zinc, to form a sacrificial anode surface to achieve cathodic protection.

Coating corrosion inhibitors (corrosion inhibitors) also improve the corrosion resistance of coatings through the effects of the above four aspects.

1. Definition of paint corrosion inhibitor (stop) (corrosion inhibitor)
Any substance that can reduce the corrosivity of the medium and prevent the metal from being corroded by adding a small amount to the medium should belong to the list of corrosion inhibitors. Corrosion inhibitors are also called corrosion inhibitors. At present, there is no uniform definition of ptfe powder canada corrosion inhibitor. The “Standard Definition of Corrosion and Corrosion Test Terms” (AS TMG 15-76) published by the American Society for Testing and Materials defines corrosion inhibitor as: “Corrosion inhibitor is a It is a chemical substance or compound that can prevent or slow down corrosion when it exists in the environment (medium) in an appropriate concentration and form. “Corrosion inhibitor as a material, it can reduce the corrosion of corrosive media.

2. Classification of corrosion inhibitors
Due to the wide variety of corrosion inhibitors, their use conditions are different, and the mechanism of corrosion inhibitors is very complex, so far, there is no one that can reflect the composition, structure and internal relationship of corrosion inhibitors. Classification. The common classification methods are as follows.

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