Selection of additives in water-based coatings

The amount of additives in water-based coatings is generally very small, but the effect is very large.
because of the low viscosity of water, high surface pressure and film-forming material in the water as a dispersion phase, resulting in water-based paint in the preparation process more dependent on a variety of additives.
than solvent-based coatings, water-based paint has more serious de-foaming and de-foaming, flow and leveling, mold prevention, thickening and other problems

. In addition, the film-forming film of water-like paint is a non-versal, non-molecular grade irreversible process, in order to form a high-quality paint film, but also with the help of film-forming additives plasticization.
, water-based paint is much more dependent on additives than solvent-based paints, so the choice and application of additives will certainly have a greater impact on product quality.
thickeners, moisturizers, dispersants, desiccants, film-forming additives are the most commonly used additives, the following for these additives, a brief analysis.
, thickener
thickener is used to regulate the viscosity and fluid properties of water-specific paints to meet the requirements of production, storage, construction and paint film performance.
different thickeners have different roles in their application and need to be adjusted according to different systems and needs.
1, increase storage stability, prevent hanging, increase film thickness, reduce fluidity should choose a low shear thickener to increase the false plasticity of the paint liquid
2, increase the paint liquid anti-splash, wet film flow leveling, wetting, dry film gloss, permeability, flat polyurethane-type thickener effect is better;
3, promote silver powder directional acrylic or directional wax increaser.
, wetting agent
wetting agent is generally divided into substrate wetting agent, wetting leveling agent, wetting dispersant.
the first two focus on wetting the substrate and the coated surface, which promotes wetting of pigments and fillers to help disperse. Wetting agents generally refer to the first two.
substrate wetting agent: The
is to promote better wetting of the coating substrate. Different types of substrate moisturizers have different abilities to reduce coating surface stress, while the ability to reduce dynamic surface stress and static surface stress is also different.
, the lower the surface pressure, the faster the reduction speed (low dynamic surface pressure), the better the effect.
wetting leveling agent:
substrate moisturizer is more focused on the affinity to the solid surface, wetting leveling agent is more targeted at the liquid on the substrate even distribution of the ability.
application, leveling agent has a better effect to prevent shrink holes, in the case of shrinkage has occurred, can also overcome the shrinkage of the paint film phenomenon.
most wetting agents have the role of substrate wetting and lacquer film leveling, sometimes it is difficult to completely separate the two. In general, the main action of fluid leveling is called wetting leveling agent;
3. There are many kinds of dispersants
, generally through electrostation adsorption, spatial resistance so that particles are evenly dispersed in the medium and prevent flocculation and appendage.
, there are inorganic, organic classification, but also anion, cation, non-ion classification.
Different dispersant applications are also very different, some suitable for dispersing inorganic powder, some suitable for organic pigments, some suitable for dispersing carbon black;
SV-246H as a multi-functional hydrophobic dispersant, with good dispersion capacity, excellent water resistance, color display and light preservation performance, and good compatible with organic pigments and so on. As a result, it has been widely used and well received.
, anti-foaming agent
anti-foaming agent, foaming agent, de-foaming agent collectively known as de-foaming agent. Select deblistering agent, on the one hand to achieve de-foaming purposes and maintain the durability of de-foaming capacity, on the other hand, also pay attention to avoid other side effects on the lacquer liquid or paint film, such as shrinkage, loss of light, reduced transparency and so on.
the amount of anti-foaming agent to be determined through experiments, excessive dosage can easily cause shrink holes, edges, affect re-painting, etc. , insufficient dosage can not achieve deblistering effect.
the choice of desiccant generally has the following points:
1, debobbling capacity;
2, compatible;
3, construction performance and paint film performance;
4, after storage of anti-foaming, de-foaming capacity.
, film additives
water-based paint is water as a dispersion medium, but in order to improve part of the performance, still need to add part of the solvent. The role of solvents in water-based paint is to help film forming, improve dryness, adjust the appearance of paint film and so on.
most film-forming additives can play a role in reducing film-forming temperature, but often need to be fully considered to meet more requirements.
1, film-forming efficiency: This is related to the addition of film-forming additives, that is, the coating VOC content has a great impact;
2, dryness: different solvent volatilization rate is very different, choose different film-forming additives, will greatly affect the drying, do-drying speed;
3, compatible: some solvents directly added to the emulsion may cause a greater degree of impact on the emulsion, resulting in broken milk, generally related to the water solubility of the solvent, poor water solubility is more likely to cause this problem


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