Improve surface levelling of powder coating with semi-crystalline polyester resin

• The levelling performance of polyester powder coating is not as well as liquid coating due to its matrix polyester resin.
• The semi-crystalline polyester resin was introduced to improve the levelling performance of the polyester powder coating.
• The semi-crystalline polyester powder coating exhibited fast reactivity and better levelling performance.

The levelling performance of polyester powder coating is not as well as liquid coating due to its matrix polyester resin. 1,6-hexanediol (HDO), neopentyl glycol (NPG), terephthalic acid (PTA), isophthalic acid (IPA) were used to synthesize semi-crystalline polyester resin (HDO, PTA and IPA) and amorphous polyester resin (NPG, PTA and IPA). The semi-crystalline polyester resin was introduced to powder coating for further use. The structure of semi-crystalline polyester resin was characterized by 1H-nuclear magnetic resonance (1H NMR) and X-ray powder diffraction (XRD). The viscosity of the polyester resins were investigated by cone-and-plate viscometer (CPV). The reactivity of the coatings was characterized by differential scanning calorimetry (DSC). The levelling performance was studied by flow, cone-and-plate viscometer (CPV), atomic force microscope (AFM) and scanning electron microscope (SEM). The results showed that the semi-crystalline polyester powder coating had higher reactivity and better levelling performance than that of amorphous polyester powder coating.

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