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Application of Zinc Stearate Emulsion in Coatings

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Update time : 2019-10-18 11:39:35

Zinc stearate emulsion is mainly used in wood coatings in coatings to fill and improve sanding. This paint has excellent Transparency and affects the Transparency of the color, especially for transparent primers. In addition to the emphasis on grinding and Transparency, zinc stearate emulsion has some other influencing factors such as oil absorption, Thickening, particle size and dispersibility, which also affect the overall performance of wood lacquer.

 

Zinc stearate emulsions have several technical indicators in the wood primer that affect the performance of the paint:

 

1, Grinding

 

Inwood primers, the sanding performance, is an essential indicator in the paint. The usual test method is to use the same paint formulation, and the spray plate is sanded at the same time, there is no fixed standard. If only one paint manufacturer of zinc stearate emulsion is used, it does not matter whether the grinding property is good or bad. Still, the competition in the market leads to the comparison of the products and also stimulates the further development of the zinc stearate emulsion grinding aid. The quality of the sanding performance directly affects the speed of the construction and affects the replacement frequency of the sandpaper, which directly affects the cost of the furniture manufacturer. Generally, the proportion of zinc stearate emulsion in the primer is 5-10%. Still, some white textbooks which are not required for high Grinding and low cost also do not contain zinc stearate emulsion and add a large amount of talcum powder. And calcium carbonate to improve quick-drying and sanding. For the Grinding of zinc stearate emulsion, the manufacturers are not necessarily the same, and the grinding properties of the different materials from the same manufacturer may be slightly different. For example, if the acid value of the semi-finished product produced and the temperature at the time of synthesis are somewhat different, it will have more or less influence on the finished product. Therefore, in the production of zinc stearate emulsion, not only the process should be stable, but also the process should be continuously improved to improve the grinding performance of the zinc stearate emulsion.
 

 
 

2, Transparency

 

In transparent primers, Transparency directly affects the aesthetics of the wood. Therefore, zinc stearate produced by the water method cannot be used in transparent wood lacquers, mainly because of too many impurities. The direct production of zinc stearate can meet the requirements in terms of purity, but the requirements for the process are also very high. Different production processes have a significant influence on Transparency. The slight difference in the process may lead to a massive difference in Transparency. Therefore, although many manufacturers directly produce zinc stearate, it is rare to use it in the coatings industry. This is also the core technology for coating zinc stearate enterprises. Transparency is usually detected by dispersing a certain proportion of resin, solvent, zinc stearate, test sample, and standard sample, and then coating a film on black and white paper or glass with an applicator to see the degree of Transparency.

 

3, Thickening

 

The manufacturer of the coatings does not accept the Thickening of the zinc stearate emulsion. Because the zinc stearate emulsion is added to the surface to make the finished product, the viscosity is determined, and the factory specifications are fixed, even if the error is also ± 500mP·s, so the method of testing zinc stearate emulsion thickening is generally also experimented with a rotary viscometer. If the viscosity of the just dispersed Dispersion is more than 500 mP after a few hours, it is considered Thickening. If the zinc stearate emulsion is thickened, the finished product test produced by the paint manufacturer will be very different from that used, even if the viscosity required for the production of the paint is relatively large, and the zinc stearate emulsion is thickened, so May cause the paint to flow at all, especially PE coatings, resulting in curing scrap.

 

4, Oil absorption

 

The oil absorption and Thickening are not considered to be the same concept. The oil absorption is significant under the condition of the same proportion of addition, and the viscosity of the finished product is large. The thickness for some time does not exceed the error value ±500mP·s. The test standard for oil absorption is “DIN ENISO787-5-1995”. Generally, there is not much requirement for oil absorption in PU coatings, because it will not have too much impact on production, and there are also high requirements for oil absorption by paint manufacturers. This may be because some paint manufacturers add more solvents, but want to reduce the volatilization of the water, it is necessary to find some substances with high oil absorption, and the oil absorption of zinc stearate emulsion is higher than other additives. Auxiliary.
 

 

5, Particle size

 

The particle size is an indicator of the size of the zinc stearate particles and is generally measured by fineness. Usually, the test is the simplest. The quickest result is the scraper fineness. Typically, a certain proportion of zinc powder is added to the alkyd resin. Then add a little solvent to adjust the viscosity, and then test with a scraper fineness meter. The test results will be slightly larger than the actual fineness because the resin-coated powder occupies a certain thickness. Still, as long as the standard is comparable and repeatable, the test method can be used to measure whether the fineness exceeds the norm. In the paint, the fineness of zinc stearate should not be too large, which will cause the effect of the spray plate to be the particles on the surface of the plate, and some areas that are not polished will show unevenness. However, zinc stearate emulsions do not have these problems.

 

6, Dispersion

 

 In the production process of paints, many manufacturers also mentioned the problem of Dispersion. Under normal circumstances, the Dispersion of zinc stearate emulsion in color is not problematic. Still, in the production process of zinc stearate emulsion, some indicators will also have some influence on the dispersibility, such as stearic acid. The acid value of zinc is too high, the temperature of the semi-finished product is too high, and the problem of poor dispersibility of zinc powder in the coating occurs when the worker presses the bag too seriously. At the same time, if the moisture in the zinc powder is too high, the crystallization problem may occur. Dispersion is not good. Similarly, zinc stearate emulsions solve these problems well.