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Why Catalysts are Used in Alkyd Coatings

Alkyd coatings are one of the most cost-effective alternatives to epoxies and 2K polyurethane paints. These coatings cure via oxidative drying when certain unsaturated film formers crosslink in the presence of atmospheric oxygen. To accelerate this process, either cobalt driers or high-performance catalysts (HPCs) are used. Choosing the right catalyst for an alkyd formulation can also improve durability by enhancing critical properties such as weatherability, hardness, corrosion prevention, and gloss retention.

This article will highlight how our novel Borchi^® HPC technology can take coating performance to the next level by enhancing durability in alkyd-based formulations. The data will showcase comparisons of Borchi OXY-Coat HPC and current technologies available in various market segments, including decorative and industrial systems for direct-to-metal application.

 

Systems Evaluated for Enhanced Durability with HPCs

Borchi OXY-Coat was tested against cobalt across multiple systems. Dry times, hardness, corrosion resistance, and gloss were evaluated to determine the best application types for HPC-enhanced alkyd coatings.

 

 

 

Dry times were measured with Circular Drying Recorders after applying drawdowns on Mylar sheets.

Hardness was tested with drawdowns on glass plates and measured with König hardness according to ISO 1522 after up to 14 days.

Corrosion resistance was measured with a Q-FOG corrosion tester run according to ASTM B117 up to 1000 hours using drawdowns applied on steel panels with the edges and rear side masked and a cross scribed on the lower part.

Gloss was measured according to ISO 2813 periodically during the exposure time.

Drawdowns were all applied using a bar or frame applicator with a wet film thickness according to the respective customer specifications.

 

Protective & Marine Coatings

The first system compared HPCs against cobalt driers in a solvent borne long oil alkyd direct-to-metal paint formulation. All coating properties were evaluated, showing that the formulation containing Borchi OXY-Coat provided excellent dry times, significantly improved corrosion resistance, higher gloss retention, and comparable hardness in relation to the cobalt drier.

 

General Industrial Coatings

Two types of paints were formulated for General Industrial applications. The first system was a solvent borne pigmented short oil alkyd coating for direct-to-metal light industrial applications. When tested against cobalt, Borchi OXY-Coat exhibited faster drying times, excellent hardness, and significantly improved corrosion resistance. Gloss was not measured as this system required a matt finish.

 

The second system was a solvent borne pigmented long oil alkyd topcoat formulation for metal and wood. All coating properties were evaluated, showing that the formulation containing Borchi OXY-Coat exhibited faster dry times, significantly improved corrosion resistance, high gloss retention, and good hardness in relation to the cobalt drier.

 

 

Architectural Coatings

The final system tested was a solvent borne long oil linoleic rich alkyd formulation on 46% resin solids for high gloss trim applications. All coating properties were evaluated, including an additional test for adhesion, and showed that the formulation containing Borchi OXY-Coat provided faster dry times in standard and adverse conditions, significantly improved corrosion resistance and adhesion, higher gloss retention, and comparable hardness in relation to the cobalt drier.

The Q-FOG salt spray and adhesion tests are important test parameters for decorative paints and varnishes as these paints are used on a wide variety of substrates. For example, when wood is varnished, the metal fittings and nails on the substrate are also varnished; if these are not properly protected, their metallic surfaces can rust.

 

 

 

 

 

Regulatory & Sustainability Benefits of HPCs

While HPCs are excellent solutions for enhanced drying and durability in alkyds, these drying additives are also free of cobalt, a metal facing increased regulatory pressures in the paint and coatings industry. Several countries around the world are considering the regulation of cobalt in applications like coatings based on its toxicity and sourcing concerns. To learn more, check out our recent blog on Sustainability and Regulatory Challenges for Cobalt in the Coatings Industry.

 

Conclusion

Borchi HPCs decrease dry times while improving paint durability in alkyd formulations regardless of the final hardness of the coating. These drying additives go beyond reducing dry times by enhancing additional performance properties such as corrosion resistance, adhesion, and gloss retention. Borchi HPCs are a great alternative to expensive 2K polyurethane and epoxy systems and allow paint formulators to ’future-proof’ alkyd coatings from cobalt regulations, creating more sustainable formulations in turn.

 

For more information, please visit borchers.com/HPCs