A kind of hydroxyalkylamide cured anti-pinhole polyester resin and powder coating prepared therefrom

Abstract

The invention discloses a hydroxyalkylamide cured anti-pinhole polyester resin and a powder coating prepared therefrom. The powder coating comprises the following raw materials in mass percentage: 50-70% of polyester resin; 1.8-70% of hydroxyalkylamide 2.6%; leveling agent 0.8-1.2%; pigment 8-25%; inorganic filler 0-25%; additive 0-5%. The invention reduces the amount of HAA curing agent used, reduces the release of small molecules such as water during the curing process of the coating film, and greatly reduces the pinhole phenomenon on the surface of the coating film. Compared with the conventional powder, the pinhole phenomenon occurs at 90-100 μm. Individual pinholes begin to appear only when the coating reaches 130 μm or more, and the anti-yellowing effect is also significantly improved compared with conventional HAA cured powder coatings.

Description

technical field [0001] The invention belongs to the technical field of paint preparation, and in particular relates to a hydroxyalkylamide curing pinhole-resistant polyester resin and a powder paint prepared therefrom. Background technique [0002] With people's awareness of environmental protection and the country's emphasis on environmental protection, powder coatings, as an environmentally friendly coating, are being used more and more widely. Among the weather-resistant powder coatings, TGIC and HAA are the two most widely cured types. However, because TGIC has certain toxicity and harm to the environment, and it is easy to cause skin allergies to workers during use, it has been used in developed countries such as Europe. Prohibited use. HAA (hydroxyalkylamide) is a low-toxicity curing agent, so it has gradually become the development trend of weather-resistant powder coatings. [0003] However, the HAA system powder coating also has certain defects. During the curing ...

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Problems solved by technology

[0003] However, the HAA system powder coating also has certain defects. During the curing and crosslinking process with the polyester resin, water molecules will overflow, and the reaction speed is fast, which is easy to produce pinholes on the surface of the coating film, which not only affects the appearance of the coating, but also causes Decreased water resistance of coating film

The acid value of the polyester resin in the existing HAA curing system is usually 28-38mgKOH / g, and the curing ratio to HAA is 95:5. After curing, the coating film is 90-100μm thick and pinholes will occur. The thicker the thickness, the pinholes The more obvious the phenomenon is, the difference between the pinhole phenomenon and the film thickness of TGIC curing system is 120-130μm is obvious.

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