Selection of wet dispersion in Coating formula

Wetting and dispersing agents are very important for wetting and dispersing effects in coating formulation design. To choose a suitable wetting and dispersing agent, you need to know the following information before designing the mill formulation:

1. Application fields of coatings: According to the characteristics and requirements of different application fields, corresponding wetting and dispersing agents should be used.

2. Types of coatings (primer, top coat, base coat): Different types of coatings have different performance requirements.

3. Type and polarity of the system: Wetting and dispersing agents need to have good compatibility with the system to work.

4. Pigment: Pigment type (organic/inorganic/effect pigment/carbon black), specific surface and surface chemistry (acidic/alkaline): Different pigments have completely different dispersion characteristics, which require different wetting and dispersing agents corresponding to them. Form a firm adsorption on its surface.

5. Co-grinding or color separation grinding: the former requires a compromise solution, while the latter can optimize the grinding conditions.

6. Whether there is grinding resin or not: Generally, there are corresponding wetting and dispersing agent product suggestions for whether there is grinding resin or not.

The choice of wetting and dispersing agent is simply the choice of two aspects: the type and amount of dispersing agent. As with all other additives, the correct dosage of wetting and dispersing additives is very important. The amount of wetting and dispersing additive used to stabilize the pigment depends on the specific surface area of ​​the pigment. Since the dispersant needs to cover the entire pigment surface, pigments with larger surface areas (i.e., smaller particle sizes) require more dispersant. The oil absorption and BET surface area of ​​the pigment can be used as a reference for the amount of dispersant.

The amount of dispersant is closely related to the following factors:

      1. It is related to the end use of the coating: due to cost considerations, the amount of dispersant in architectural coatings is generally low, while in automotive coatings, a higher amount is required to obtain better performance.

      2. It is related to the type and chemical properties of the base material: the wetting and dispersing effect of the resin in the coating is different, which will affect the amount of wetting and dispersing agent used.

      3. It is related to the chemical properties of the wetting and dispersing agent: due to the relative molecular weight and chemical structure, the addition amount of low molecular weight additives is lower than that of high relative molecular weight additives.

      4. It is related to the particle size of the pigment: transparent titanium dioxide requires about 5 to 8 times more dispersant than ordinary titanium dioxide.