Polyethylene wax in coatings

Polyethylene wax in coatings

Polyethylene wax in coatings

When polyethylene wax is used in water-based inks and coatings, oxidized polyethylene wax is usually employed, and emulsifiers are added to create emulsions or disperse it with internal acid resins. Oxidized polyethylene wax enhances its hydrophilicity to some extent. This water-based dispersion of vinyl wax is prepared by treating micro-powdered polyethylene wax with a super-dispersing FA. Through homogenization, it is dispersed in deionized water containing ammonia in the form of a thick slurry. After the ammonia evaporates with the water, the polyethylene wax particles lose their hydrophilicity and float on top of the coating, fulfilling their role as a wax. The dispersion is extremely easy to disperse in water-based oil masks, color pastes, and coatings, and can be added at any stage, either by grinding with the coating components or directly at a later stage. The dosage is according to proven formulations.

Mechanisms of polyethylene waxes in coatings

Frosting Effect: When the wax’s melting point is lower than the baking temperature, the wax dissolves into a liquid state during baking, after the film cools down, it forms a thin frost-like layer on the coating surface.

Spherical Axis Effect: When the particle size of the wax is similar to or slightly larger than the coating thickness, the wax becomes visible one the coating surface, enhanceing scratch resistance.

Floating Effect: Regardless of the wax’s particle morphology, it drifts to the coating flim’s surface and uniformly disperses during the film-forming process. This process protects the uppermost layer of the coating film, showcasing the wax’s characteristics.[1]

Main functions of polyethylene wax in coatings

Matting: Polyethylene wax forms a microscopic uneven structure on the surface of the coating film, reducing the reflection of light on the surface and imparting a matte effect to the coating.

Anti-scratch, Anti-wear, Anti-polishing, Anti-engraving: polyethylene wax exhibits excellent hardness and abrasion resistance, protecting the coating film surface from scratches and abrasion, extending the service life of the coating film, and simultaneously enhancing the durability of the coating film.

Thixotropy: The thixotropy of polyethylene wax facilitates the storage of coatings, preveting precipitation and delamination of coatings during storage. After application, the wax migrates to the surface of the coating film, eventually forms a "waxed" layer with the other components of the coating.

Lubricity and Processability: PE waxes are highly compatible with coating resins, providing excellent external and internal lubrication. This reduces friction during production and application, improving the flow of the coating and making it easier to apply to the substrate.

Positioning of Metallic Pigments: Polyethylene waxes aid in positioning metallic pigments in the coating, enhancing the hiding power and metallic luster.

Anti-adhesion and Anti-precipitation: PE wax enhances the anti-adhesion performance of the coating film, preventing adhesion under high temperature and pressure. Simultaneously, it improves the suspension performance of the coating, preventing pigments and fillers from precipitating.

In conclusion, the application of polyethylene wax in coatings aims to enhance the weather resistance, durability, aesthetics, and processing performance of the coating film through its unique physical and chemical properties.

[1] 田俊京.微粉蜡在涂料中的应用研究[J].网络财富,2010(12):262.