4 functions of polymeric dispersing agent in paint

1, It can greatly reduce the interfacial tension between pigment and base material, reduce the viscosity of grinding system, and make the operability easier.

2, Especially for the grinding and dispersion of high surface carbon black FW200 and 5000, it has very high blackness.

3, It can increase the color spreading power of pigment, especially for the resin with poor wetting property, it can improve the glossiness.

4, Reduce the viscosity of paint, increase the solid content and good stability, shorten the grinding time and improve the fineness of grinding.

The choice of defoamer
How to choose a defoamer, in addition to achieving the purpose of defoaming, there must be no side effects. These side effects mean that there are no problems in the color development and aggregation of the pigments, and there are no defects such as shrinkage, pinholes, loss of gloss, shrinkage, silk lines, and laughter. The durability of defoaming ability is an important requirement for choosing paint defoamers. The long-lasting performance of defoaming performance needs to be maintained for a few days during the coating production process. However, in the construction after storage, it is more difficult to maintain the initial defoaming ability. The presence of surface active substances in the coating, as well as the high temperature and high shear force during the coating manufacturing process are not conducive to the durability of the defoaming ability. Therefore, the choice of defoamer for coatings is still based on practical experience, careful consideration of actual factors, and adjustment of the formula to achieve an optimal point of balance and stability. Recently, there are many suppliers of coating additives at home and abroad, and they will also recommend some products to provide options. The steps for selecting a defoamer are described below.

①Collect the technical data of resins, surfactants, pigments and other materials: including application construction methods, drying conditions, and requirements for durability of defoaming ability, etc. Combine the work done in similar areas in the past and consult the literature for a careful analysis.
②Select several defoamer varieties, adopt the post-addition method, and complete the preliminary screening. That is to test in the pre-prepared coating samples without defoamer. This should include accelerated tests of heat aging defoaming ability durability and construction process simulation tests.
③Using the best results obtained in the above screening in the coating manufacturing process, wax dispersion use adding defoamers at the selected stage, and then making appropriate adjustments to obtain the best results.
④ When there are several defoamer varieties that can meet various performance requirements, if the cost is acceptable, the variety with less dosage should be selected. Because defoamers are relatively low-molecular substances and will not form a film, they will always affect the quality of the coating film.