Powder coating

1. Experimental Section

1.1 Raw Materials

• Hydroxy polyester resins with hydroxyl values ranging from 100 to 310 mgKOH/g.

• Flow modifiers including modified polyethers, polysiloxanes, and fluorocarbon compounds.

• Other ingredients: benzoin, pigments, barium sulfate.

1.2 Equipment

• Twin-screw extruder

• High-speed grinder

• Film thickness gauge

• Impact tester

• Adhesion tester

• Dyne pens

1.3 Testing Standards Testing followed domestic kitchen appliance industry specifications for easy-to-clean performance.

2. Results and Discussion

2.1 Effect of Flow Modifiers on Easy-to-Clean Performance Flow modifiers significantly reduce surface tension, a critical factor for achieving an easy-to-clean coating. Although fluorocarbon compounds offer superior performance, they tend to introduce surface defects and are harder to source. Modified polysiloxanes emerged as the optimal choice due to their balanced appearance and performance.

2.2 Effect of Resin Hydroxyl Value Higher hydroxyl values in polyesters improve stain resistance and aging performance. However, mechanical properties such as impact resistance may degrade. Balancing reactivity and mechanical integrity is key to formulating a reliable easy-to-clean coating.

2.3 Influence of Common Additives Conventional additives like PE wax, PTFE wax, PA wax, and leveling agents such as 701 negatively impact easy-cleaning properties. These substances may float to the coating surface, altering surface tension and reducing performance.

2.4 Filler Content Impact Barium sulfate up to 20% retains acceptable easy-cleaning performance. However, beyond that, markings like oily pen strokes become difficult to remove, reducing overall coating effectiveness.

3. Conclusion

The optimal easy-to-clean coating formulation for kitchen appliances includes:

• Hydroxyl polyester resin with ~200 mgKOH/g

• Modified polysiloxane flow modifier

• No wax-based additives or surface tension modifiers like 701

• Filler (barium sulfate) below 20%

This formulation achieves comparable performance to liquid coatings but at a lower cost. Given the increasing industry shift from liquid to powder coatings, this easy-to-clean powder coating is positioned to become a strong alternative in the kitchen appliance sector.