Multilayer Primer-Surfacer Coating Resolving Stonechip and Bird-Dropping Resistance

The patent uses a composite binder system comprising at least two different polyesters with distinct glass transition temperatures (one ≥20°C and another ≤10°C). This composite material approach combines the benefits of both polyesters: the higher Tg polyester provides stonechip resistance while the lower Tg polyester maintains flexibility and adhesion, preventing delamination when birds droppings occur. The synergistic interaction between the two polyesters resolves the contradiction between stonechip protection and adhesion stability.

The patent applies parameter changes by carefully controlling the glass transition temperatures of the polyester components and their weight ratios. By adjusting these parameters, the coating achieves an optimal balance: the higher Tg polyester (≥20°C) provides the hardness needed for stonechip resistance, while the lower Tg polyester (≤10°C) ensures the coating remains flexible enough to maintain adhesion under thermal and mechanical stress from bird droppings.

The patent employs a composite material strategy by combining two polyesters with complementary properties. The first polyester (Tg ≥20°C) contributes to stonechip resistance through its higher crosslink density and rigidity, while the second polyester (Tg ≤10°C) provides flexibility and elongation. Together, they create a coating that is both strong and flexible, resolving the contradiction between strength and ease of operation.

The patent applies local quality by assigning different functional roles to different polyester components within the same coating system. The higher Tg polyester locally provides hardness and chip resistance where needed, while the lower Tg polyester locally provides flexibility and adhesion in areas susceptible to thermal and mechanical stress, achieving both properties simultaneously throughout the coating.