Weathering additives for Automotive coating


Ø Main types of automotive coatings

> Automotive Primer

Automotive primers have gone through several major changes such as oil-based primer, nitro primer, alkyd resin primer, epoxy resin primer, water-based primer for dipping, anionic electrophoretic primer, cationic electrophoretic primer and powder primer.

At present, it is the cathodic electrophoresis process that is widely used. The main resins of electrophoresis coatings are acrylate resin, epoxy resin, polybutadiene and polyurethane.

>Intermediate coating and top coating

Water-based coatings: Water-based coatings use water as solvent and only a small amount of alcohol ether as co-solvent, and are formulated with different water-based resins, which can be divided into water-soluble, colloid-dispersed and emulsion types. Water-based primer is mainly water-based acrylic paint and water-based polyurethane paint.

Powder Coatings: Powder coatings are mainly epoxy-polyester hybrid, polyester, polyurethane and acrylate. Enhancing the weather resistance, UV resistance, thin film and decorative properties of powder coatings is the future research direction.


Ø Why does UV-aging occur in Automotive coating?

Light, high temperature and humidity are the main causes of automotive paint loss of light, fading, yellowing and chalking. The weathering superiority of the coating is related to the spectral sensitivity of the coating components.

High temperature is also an important factor in the aging of automotive paints. When the temperature rises, the destructive effect of UV-aging also increases.

Humidity: Dew, rain and high humidity are also factors that should not be overlooked as contributors to aging.

Ø How to choose the right weathering additives for automotive coatings?

The main resin of automotive coatings mainly consists of epoxy resin, amino resin, polyester resin, polyurethane etc. It contains functional groups such as C-C, C-H, O-H, C-O, etc. Different functional groups have different bonding energies. Different functional groups have different bond energies and different sensitivities to light, resulting in differences in weathering resistance. Therefore, the key to improve the weatherability of coatings is to select UV absorbers that cover the sensitive wavelengths of the resin!


Today we'd like to share with you some effective weathering additive combined solutions:

>>UV absorber

- For Epoxy/PU coating system



Both additives belong to Formamidine-type absorber, could highly absorb the UV band which epoxy and polyurethane are sensitive.

- For Water-based coating

> OMNISTAB UV1130 is one of our key liquid benzotriazole UV absorbers that have been steadily produced for many years. UV1130 is widely used in Automotive refinish coating.

- For Automotive and industry coating

> OMNISTAB UV384-2 could widely absorb the UVB and UVA band, it's suitable for the s high-end automotive and industrial coating.

> OMNISTAB UV400 is a new type triazine UV absorber that exhibits high thermal stability even under high baking or extreme conditions.


- For PU coating


HN130 is water-based and especially suitable for water-based eco-friendly coatings. It can effectively protect the gloss of coatings and preventing them from yellowing. 


AN6133 is suitable for solvent-based PU coating, it's no phenol, low volatile and Eco-friendly. AN6133 help to improve the thermal stability of PU coating, and slow down the yellowing problem.


- For Acid coating system


Compared with traditional HALS (like LS292), OMNISTAB LS123 is a kind of NOR-type HALS, which shows weak alkalinity. It can avoid the reaction with acid components in coatings, and provide better stability.

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