Polyvinyl chloride/epoxy double layer powder coating enhances coating adhesion and anticorrosion protection of substrate

• Published in: Progress in organic coatings 2021-09, Vol.158, p.106335, Article 106335
• Main Authors: Wang, ChuanXing, Han, YuYing, Wang, Wenxue, Liu, Juan, Wang, Ning, Hou, BaoRong
• Format: Article
• Language: English
• Subjects: Adhesion; Anticorrosion; Corrosion environments; Corrosion prevention; Corrosion resistance; Corrosion resistant steels; Curing; Double-layer coating; Environmental protection; Epoxy resin; Epoxy resins; Marine environment; Offshore structures; Polyvinyl chloride; Powder coating; Primers (coatings); Protective coatings; PVC; Salt spray tests; Spraying; Substrates
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2021.106335

[Display omitted] •Novel environment-friendly double layer powder coating modified by epoxy (PVC-PVC/EP) was prepared to improve the adhesion and corrosion resistance of the coating.•Compared with the two curing methods of double layer powder coating, the layer by layer curing method has lower porosity, stronger shielding effect and better comprehensive properties than the co-curing method.•When the amount of epoxy in the primer is 50wt%, it can effectively enhance the adhesion of the coating by forming covalent bonds with the metal surface by hydrogen bonds.•The excellent corrosion resistance of the double-layer coating is mainly due to the epoxy in the primer improves the adhesion of the coating, and the PVC in the topcoat improves the barrier of the coating. To reduce the harm of solvent based coating to the environment, a new type of composite powder coating with environmental protection and good corrosion resistance was reported. The epoxy resin modified PVC powder coating was used as a primer and pure PVC powder coating as a topcoat, which could be applied to the corrosion protection of steel in marine environment by electrostatic spraying. The structure of the coating was confirmed by SEM, FT-IR, Raman and TEM, and the effects of co-curing and layer-by-layer curing on the coating were compared. The mechanical property test, salt spray test, SEM and AFM results revealed that the material obtained the highest adhesion and salt spray resistance when the epoxy content in the primer was 50 wt%. In contrast to the pure epoxy coating and the pure PVC coating, the EP-PVC coating exhibited an excellent corrosion resistance, owning to the good adhesion of composite primer and the good barrier and corrosion resistance of the topcoat.