Zinc stearate  is mainly used as wood primer in the paint to fill and improve the sandability. Good transparency, little influence on the transparency of paint, especially for transparent primer. In addition to focusing on polishing and transparency, zinc stearate also has some other influencing factors, such as oil absorption, thickening, particle size, dispersion, which also affect the comprehensive performance of wood paint. 

Sainuo  Zinc Stearate can Inhibit initial coloring, avoid vulcanization pollution, good lubricity, mold release and adhesion.

There are several technical indexes of Zinc stearate in wood primer that affect the performance of the paint:

1. Grinability

In the wood primer, the sanding performance is a very important indicator in the paint. The common test method is to use the same paint formula, and the spray plate is sanded and tested in the same time. There is no fixed standard. The quality of sanding performance directly affects the speed of construction and the replacement frequency of sandpaper, thus directly affecting the cost of furniture manufacturers. In general, the proportion of zinc stearate in primer is 5-10%, but some white primers with low requirements on burnability and low cost also do not add zinc stearate, which can be improved by adding a large amount of talcum powder and calcium carbonate. For the burnability of zinc stearate, different manufacturers are not necessarily the same, and the burnability of materials from different manufacturers may be slightly different. For example, if the acid value of the semi-finished products and the temperature at the time of synthesis are slightly different, the finished products will be more or less affected. Therefore, when producing zinc stearate, not only the process should be stable, but also the process should be constantly improved to improve the grinding performance of zinc stearate.

2. Transparency

In transparent primer, the quality of transparency directly affects the aesthetic degree of wood. Therefore, zinc stearate produced by water method cannot be used in transparent wood paint, mainly because there are too many impurities. The purity of zinc stearate produced by the direct method can meet the requirements, but the requirements for the process are also very high. Different production processes have a great impact on the transparency, which may be caused by the small differences in the process. Therefore, although there are many manufacturers producing zinc stearate by direct method, few can be used in the coating industry. This is also the core technology of coating zinc stearate enterprises. The usual test method for transparency is to disperse a certain proportion of resin, solvent and zinc stearate, with one test sample and one standard sample, and then apply a film on black and white paper or glass with a coater to see the degree of transparency.

3. Oil absorption

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 a great impact on production. Some coating manufacturers have high requirements for oil absorption. This may be because some coating manufacturers add more solvents and want to reduce the volatilization of solvents, so they must find some substances with high oil absorption, The oil absorption of zinc stearate is higher than other additives. However, PE coatings generally require low oil absorption, because when the formula is determined, the lower the oil absorption, from production to use, will reduce or avoid the risk of product curing due to excessive viscosity.

4. Particle size

Particle size is an indicator of the size of zinc stearate particles, generally measured by fineness. Generally, a certain proportion of zinc powder is added to the alkyd resin to disperse, and then a little solvent is added to adjust the viscosity, and then the scraper fineness meter is used to test. The test results will be slightly larger than the actual fineness, because the resin coated powder occupies a certain thickness, but as long as the standard is comparable and repeatable, Then you can use this test to measure whether the fineness exceeds the limit.

5. Dispersibility

In the production process of coatings, many manufacturers also mentioned the problem of dispersion. Under normal circumstances, the dispersion of zinc stearate in the paint is not a problem, but in the production process of zinc stearate, some indicators will also have a certain impact on the dispersion. For example, when the acid value of zinc stearate is too high, the temperature of semi-finished products is too high, and workers press the package too seriously, the dispersion of zinc powder in the paint will be poor. At the same time, if the moisture in the zinc powder is too high, there will be crystallization problems, It is considered that the dispersion is not good.

Qingdao Sainuo Chemical Co.,Ltd. We are manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA,EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing.

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