S16-54 black background copper flower
The factors that affect the leveling of powder coatings mainly include three aspects. One is leveling aids. Appropriate leveling aids, such as silicone resins, polyacrylate resins and fluororesins, are added to the formula of powder coatings. After melting, these additives can quickly reduce the surface tension of the coating, promote the rapid movement of the coating before curing and film formation, and eliminate or reduce surface defects such as orange peel, brush marks, ripples, and shrinkage holes; the second is the melt viscosity of the powder coating. , under a certain shear rate (750r/min; 200r/min), as the temperature increases, the intermolecular absorption force weakens, and the melt viscosity decreases significantly; but within a certain temperature range, when the temperature is fixed and the shear rate is changed At shear rate, the shear stress also changes accordingly, and the ratio of shear stress to shear rate (that is, viscosity) changes little, which shows that for Newtonian fluids or fluids whose viscosity changes are not sensitive to shear rate, this method It can roughly distinguish the quality of paint leveling. But for thermosetting powder coatings, during the melting process, along with the crosslinking and curing reaction, the higher the temperature, the faster the curing reaction, the faster the system viscosity rises, the shorter the working time, and the leveling is limited. Therefore, the melt viscosity of the powder coating cannot accurately reflect the final leveling of the coating film, and the influence of the baking process, the heating rate, and the cross-linking curing temperature on the leveling of the coating film must be considered at the same time.
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Yangzhou Jinmao Powder Coating Co., Ltd.
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