This polyester resin helps coating formulators meet elevated performance requirements in topcoat and clearcoat applications

The demanding world of coatings for automotive, aerospace, agriculture and construction equipment applications requires formulators and coating manufacturers to meet critical, increased performance requirements from OEMs and refinish customers alike. Manufacturers look for higher chemical resistance against tough and corrosive fluids, better scratch resistance and reflow characteristics, and low VOC content, all while maintaining a lower overall cost to consumers.

To meet these needs, coatings solutions often require a blend of several different resins and various additives with properties that formulators must optimize to produce the desired results. While one property may be improved with the addition of a new ingredient, it’s often at the expense of another quality in the coating system. For example, linear polyester resins can be used to provide better scratch resistance, but their traditional structure results in reduced hardness and chemical resistance — equally valuable properties in topcoat and clearcoat applications. A new hyperbranched polyester product from BASF, BASONOL HPE 1170 B, helps formulators achieve performance improvement in all three of these properties.

BASONOL HPE 1170 B’s polyester chemistry provides improved scratch resistance. Its unique hyperbranched spherical structure, paired with its dual functionality (-OH and -COOH groups), provide the high level of hardness and chemical resistance needed in these applications. The resin’s spherical structure also prevents chain entanglement typical with linear polyesters, which results in lower viscosity in solution and no negative impacts to viscosity for low VOC coatings.

BASONOL HPE 1170 B is designed for use as a co-binder (5-30 percent on total polyol solid) for clearcoat and topcoat applications. When combining it with a high-solid acrylic polyol at 25 percent, formulators can expect the following performance improvements:

 

  • Increased scratch resistance and better reflow characteristics: BASONOL HPE 1170 B allows the coating system to regain 95 percent of its initial gloss after 1 hour at 60°C
  • Higher early hardness (more than 10 times) in ambient-cure polyurethane systems
  • Higher final hardness (more than 35 percent) in both ambient-cure and force-dried polyurethane systems, compared to the addition of linear polyesters
  • Higher chemical resistance by almost 90 percent, compared to the addition of linear polyesters
  • Improved gloss retention and weathering resistance by nearly 1000 hours
  • Increased pot life and extended open times of applied coatings

 

In polyester-melamine or acrylic-melamine baking enamels, the resin can also enable enhanced curing characteristics and cost savings opportunities. Replacing 20 percent of the polyol in such a coating system enables improved film properties for a higher-performance coating or a reduction in curing time or temperature for reduced energy consumption.

Key applications for this resin include automotive refinish clearcoat, plastics topcoat / basecoat, OEM clearcoat and interior basecoat, as well as agriculture and construction equipment topcoat applications, among others.

As automotive and other manufacturers seek reduced costs without sacrificing properties, the high performance BASONOL HPE 1170 B co-blending resin helps formulators meet these demands.

Originally published in Paint Square, August 2019

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