7 common pigment dispersants for coatings and their functions

Dispersant, also known as wet dispersant, in addition to its wetting effect, one end of its active group can be adsorbed on the surface of the pigment crushed into fine particles, the other end solvent into the paint base to form an adsorption layer (the more adsorption base, the more chain Long, thicker adsorption layer), the generation of charge rebuke force (water-based paint) or entropy rebuke force (solvent-based paint), so that pigment particles long-term dispersion suspended in the paint base, to avoid flocculation again, thus ensuring the storage stability of the color paint system.
variety of dispersants, and preliminary estimates suggest that there are more than 1,000 substances in the world that are dispersed. It is divided according to its structure and can be divided into the following 7 types

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anion-type wetting dispersant
mostly consists of a non-polar, negatively charged hydrocarbon chain part and a polar hydro-hydro-friendly group. The two substumps are located at both ends of the molecule, forming an asymmetric hydro-hydro-oil-pro-oil molecular structure. Its varieties are: sodium oorate C17H33COONa, pyrate, sulfate (R-O-SO3Na), sulfonate (R-SO3Na) and so on. Anion dispersants are compatible, such as the
Shanggao special chemical Sago-9700 wetting dispersant
is widely used in water-based coatings and inks. Polycarbonate polymers can also be used in solvent-based coatings and are widely used as controlled flocculation dispersants.
cation-type wetting dispersant
is a non-polar base band positive charge compounds, mainly amine salts, gyramine salts,salts. Cation surfactant adsorption force is strong, carbon black, a variety of iron oxides, organic pigments dispersion effect is better, but pay attention to its chemical reaction with the base material, but also pay attention not to use with anion dispersant at the same time.
controlled free-form ultra-dispersant
using the latest controlled free-form polymerization technology (CFPP) to make the structure of the dispersant more regulated. Common methods are: GTP, ATRP (atomic transfer free-based polymerization), RAFT (reversible addition chain transfer controlled free-based polymerization, including C-RAFT and S-RAFT, etc.), NMP, SFRP (stable free-based polymerization), TEMPO, etc. Through the use of controlled free-based polymerization technology, the relative molecular mass distribution of dispersants can be more concentrated, anchoring groups are more concentrated and more efficient.
such as Shanggao special chemical Sago-9311, EFKA-4310 wetting dispersant,
compatibility is wide, especially for color organic pigment color display ability performance, widely used in nano-universal color paste and other industries.
non-ion wetting dispersant
is not ionized or charged in water, and adsorption is relatively weak on the pigment surface, mainly used in water coatings. Mainly divided into ethylene glycol and polyol type, reduce surface pressure and improve wetting. Used in conjunction with anion dispersants as a wetting agent or emulsifier, it is widely used in water-based slurry, water-based coatings and inks.
type wetting dispersants are
compounds consisting of anions and cations. Typical applications are phosphate-type polymers. The high acid value of these polymers may affect inter-layer adhesion.
electro-neutral wetting dispersant
molecules in the anion and cation organic group size is basically equal, the entire molecule is neutral, but polar.
polymer-type ultra-dispersants
are most commonly used and have the best stability. Polymer-type dispersants are also divided into polyheith polyester polyol-polyethylene subamine inlay co-polymer-type dispersants, acrylate polymer-type dispersants, polyurethanes, polymer polyethers or polyester-type polymer dispersants, etc., because their anchoring groups are attached to pigment particles at one end, and the other end is entangled with resin adsorption, so storage stability is relatively good. In addition, polymer dispersants are not only simple above several types of structures, they can also join each other, cooperate with each other, performance to the extreme. Such as
still high special chemical Sago-9760 wetting dispersant
widely used in water- and alcohol-water and other high-polar systems of industrial coatings, nano-universal color paste, ink, pigment inkjet, resin-free color paste system, good color display, excellent anti-sink performance, prevent floating color, stable performance!
the role of the dispersant
1, enhance the gloss, increase the leveling effect has been tested to show that the exact same formula, using different dispersants, the resulting paint film gloss will be significantly different. For example, in the black coil coating system, the coating film made of different 3 dispersants has a 20-degree gloss of 69.7%, 81.5% and 77.1%, respectively. If the dispersant used is not appropriate, the color flocculation becomes thicker, its effect on the gloss is similar to the anti-light powder, naturally affects the gloss.
2, to prevent floating hair flowers to prevent floating hair flowers, is known as one of the role of dispersants. To prevent floating hair flowers, suitable dispersants should be used, whether floating hair flowers in the tank or paint film floating hair flowers, can be improved or eliminated. There are also some dispersants, is a controlled flocculation dispersant, molecular chain contains some carboxyl groups, and pigment affinity at the same time, but also form hydrogen bonds with each other, so that pigment particles stable, to prevent floating flowering effect.
3, improve the coloring force pigment dispersion and stability better, its coloring force will be significantly strengthened.
4, reduce viscosity, increase pigment load using a suitable dispersant, the resulting color paste viscosity will be significantly reduced. This increases pigment load and increases productivity.
5, reduce flocculation, increase construction and use many people in the assessment of dispersants, will do finger research tests. If the dispersant is not properly matched, the area of study and the area of non-research will produce a significant color difference, flocculation pigment coloring force will decrease, which makes color adjustment and coating construction difficult. The flocculation of the color paste can also be observed by using the flow plate test.
6, to prevent re-coarse, increase storage stability if the selection of inappropriate dispersants, color slurry re-coarse or due to flocculation and produce color changes, are not what we hope. In addition to the resin system, dispersants are an important factor affecting the storage stability of coatings. Poorly dispersed slurry will re-coarse, subside, and decrease coloration.
7, increase color display and color saturation dispersant this effect is most easily ignored. Some examples show that different dispersants are used to disperse the same pigment, and there will be significant differences in color and saturation. In general, the better the dispersion, the higher the saturation (in the case of carbon black, the better the dispersion, the lower the L value, the higher the blackness).
8, increased transparency or cover for aluminum paint, the higher the transparency of the color paste, the better. And for plain paint, and hope that the higher the cover power of the slurry, the better. In fact, this is related to pigment particle size. Data show that, in addition to the refractive index, pigment particle size distribution is another important factor of transparency. The particle size increases and the ability to scatter light increases until the maximum value, and then begins to drop. This ability to scatter light enhances the cover of the pigment, reaching maximum when the scattering capacity is strongest, and the particle size continues to increase the covering force. And when the pigment particle size is below a certain value, transparency increases as the particle size decreases. Dispersants cannot change the properties of the pigment itself, but they can control the particle size distribution of pigments to achieve a better color effect.
9, improve grinding efficiency, reduce production costs wetting dispersant wetting function so that the pigment surface of air and water can be replaced more quickly by the liquid of the grinding medium, while the dispersion phase of the pigment primary particle separation can be maintained and controlled. These improve grinding efficiency and reduce energy and labor costs.
10, to prevent subsidon many people take for granted that anti-sinking must rely on anti-sinking agent, in fact, this is one-sided. If abrasive slurry produces flocculation, pigment particles become erred and density increases, and it will soon subside. The color paste with the appropriate dispersant can add less or even no anti-sinking agent.
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