Talk about the defoaming of airless spraying of water-based coatings

High-pressure airless spraying is an efficient construction method, which can reduce the number of sprays and paint loss. At present, widely used in large-scale components of the paint construction, such as large-scale steel, bridge terminals, container manufacturing and other fields.
principle, airless spraying is the use of high-pressure pumps to inhale the paint, and then pressurized to the hose spray gun, so that the paint sprayed

. According to Henry Law, the higher the pressure, the greater the solubility of the gas in the coating. After construction, the pressure is removed and a large amount of air dissolved inside the paint film is released, creating a lot of micro-foam (imagine us opening a can of violently shaking cola). In addition, airless spray construction process shear force is very large, will promote the formation of micro-bubbles.
by looking at the transparent paint film, we can find different construction methods, bubbles are completely different. Compared with the conventional construction method, airless spray paint film bubbles more, and mainly micro-bubbles, which undoubtedly increases the difficulty of deblistering. (Figure 1).
Figure 1 Bubbles under different construction methods
First of all, look at the application example, in The paint system of Figure 2, respectively, add different deblisters, the same airless spraying method of construction, the use of conventional desmoticant paint film inside can still observe micro-bubble residue, and the use of BYK-1785 paint film can not see bubbles.
In another transparent system of high-solid wood-containing coatings, airless spray construction has similar test results (Figure 3): by using BYK-1780 as a deboist, with fewer bubbles in the paint film than the usual competitors on the market (which are also excellent decosting agents).
Figure 3 Airless spraying, additive additions are based on the total formula
usually, the right desiccant will find a "balance" between compatibility and incompatibility: compatibility is too good, but will lead to steady foaming, not de bubbles. However, too incompatible, resulting in paint film defects such as fog or micro-holes. The best choice is to have a good deblistering effect without defects (fog shadows, micro-holes, etc.).
tests showed no significant effect of desiccant on gloss (Figure 4).
Figure 4 Desiccant addition: 0.5% based on the total formula
you can see that BYK-1780 and BYK-1785 have shown good compatible in many systems, generally no adverse effects on appearance. Alternatively, you can choose a version that is more compatible: BYK-1781. It ensures high-efficiency de-foaming performance while having better compatible. Experiments show that it is applicable to a variety of systems: including water-based acrylic, two-part PU, UV system, etc. , the transparency of the paint film and the episophonal state are not adversely affected.
Figure 5 is applied directly to the glass plate, WFT=150μm (customer system)
from Figure 5, BYK-1781 has less effect on the surface state of the lacquer film than other desobbists.
to achieve such deblistering capacity and be compatible with the system, the deboulant must make a big structural change. As shown in the figure, the molecular weight of conventional desiccant is large, so it is incompatible with the system, thus producing debouling capacity, but also at the expense of rapid migration capacity. In contrast, byK-1780/1785/1781 has a small molecular weight and is able to move quickly to the interface of bubbles and liquids, combined with a special molecular design to achieve a balance of compatibility and migration speed.
of the above
The advantages of byK-1780/1785/1781 series products include:
1. For high-pressure airless spray construction, a strong anti-microblistering ability is equally effective for large bubbles;
2. Can be used in varnish and color paint systems;
3. has minimal influence on gloss and appearance.