Fischer-Tropsch waxes are used in plastics (pvc) processing, such as injection molding, extrusion and pelletizing industries. Fischer-Tropsch wax is used in the production of masterbatches and modified plastics to help dispersion of fillers and excellent slip during compounding. It can be used as an external lubricant for PVC, and its low viscosity can improve the production speed of the product, and it can help the dispersion of the color filler during mixing. When using concentrated colors, the melted Fischer-Tropsch wax can effectively wet the dye and reduce the extrusion viscosity.
The problem of film sagging or poor corner coverage is caused by the low melt viscosity of the powder coating, followed by the slow reaction speed of the resin and curing agent. The former can be caused by adding anti-sagging agent or edge coverage. The corner covering power improver can improve the melt viscosity of the powder coating, reduce the melt horizontal fluidity and the inclined fluidity of the powder coating to solve the problem; the latter can be solved by adjusting the reaction activity of the powder coating. The sagging phenomenon of the coating film is also easy to occur when the coating film thickness is too thick in electrostatic powder coating. The problem of poor coverage of the edges and corners of the coating is likely to occur in fluidized bed dip coating, when coating objects with corners; in electrostatic powder coating, the edges of the coating are sharp, or the melting viscosity of the powder coating is too low. Or it is easy to appear when the coating film thickness is too thick.
The main function of the anti-sagging agent and the corner coverage improver is to increase the melt viscosity of the powder wood coating, or to make the powder coating produce a thixotropic effect when it is melted and leveled, so that the coating thickness of each part of the wave coating is uniform, and the coating film is avoided Sagging and uneven coverage of corners and other issues. Because the effect of anti-sagging agent and corner coverage improver is limited, first of all, in the design of the formula, choose a resin with a suitable melt viscosity according to the thickness of the coating film, and then choose a suitable curing reaction speed. For curing agents and accelerators, consider the variety and use of pigments and fillers. When the requirements cannot be met on this basis, the solution can be further solved by adding anti-sagging agents or corner coverage improvers.
The commonly used anti-sagging agents and corner coverage modifiers in powder coatings include polyvinyl butyral and ultrafine fumed silica. The main function of polyvinyl butyral is to increase the viscosity of the powder coating during melting and leveling; the function of ultra-fine fumed silica is thixotropy. The dosage of polyvinyl butyral in the formula is 1% to 5% of the total amount: the dosage of ultra-fine gas phase dioxide bricks in the formula is 0.5% to 2% of the total amount. The product specifications of the polyvinyl butyral produced by Hunan Xiangwei Co., Ltd. are shown in Table 2-27. The melting temperature is better if the melting temperature is below 180℃, and it is not good if the melting temperature is too high or too low.
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