Use dispersants well to greatly improve performance

1. Choose the right type of dispersant

High surface carbon black dispersants are mainly divided into two categories: surfactants and polymer dispersants. Surfactants are lipophilic and hydrophilic, which can effectively reduce the electrostatic attraction and cohesion between carbon black particles and avoid particle agglomeration. Common surfactants include organic acid salts, sulfonates and phosphates. Polymer dispersants have the characteristics of high molecular weight and can form a stable coating layer on the surface of carbon black, significantly reducing the specific surface area and agglomeration ability of carbon black particles. Commonly used polymer dispersants include polyacrylates, cellulose esters, etc.

When selecting a dispersant, it is necessary to comprehensively consider the dispersion effect, cost, environmental impact and specific industrial application requirements. For example, for the dispersion of high-pigment carbon black, it is recommended to use a new generation of block polymer dispersants developed based on controlled polymerization technology, such as SN-1327, SN-1352, SN-1832, etc. These dispersants have excellent viscosity reduction effects on high-pigment carbon black and can improve blackness and tinting strength.

2. Control the amount of dispersant

The amount of dispersant is one of the key factors affecting the dispersion effect. If the amount is too small, the ideal dispersion effect cannot be achieved; if the amount is too large, the formulation cost may increase and even affect the performance of the product. Therefore, in practical applications, it is necessary to determine the optimal amount of dispersant through experiments.

A common method is to make a dispersant dosage-viscosity curve. By measuring the viscosity of the system under different dispersant dosages, the amount of dispersant corresponding to the lowest viscosity point is found, which is the optimal dosage. In addition, the amount of dispersant can also be determined by observing the flocculation phenomenon. Add ionic thickener and dispersed pigment slurry to a glass plate lined with a black background and mix gently. If flocculation occurs, increase the amount of pigment dispersant until no flocculation occurs. The amount of dispersant at this time is the C-A value (concentration-flocculation value).

3. Optimize the dispersion process

The dispersion process also has an important influence on the dispersion effect of carbon black. Generally speaking, the dispersion process includes three stages: wetting, separation and stabilization. In the wetting stage, the air on the surface of carbon black or in the middle of the aggregate needs to be replaced by the base material to facilitate the next separation process. In the separation stage, shear force is applied to the carbon black mixed in the base material by mechanical equipment to shear and separate the carbon black into finer particles. In the stabilization stage, the dispersant adsorbs on the surface of carbon black to reduce the surface tension between carbon black and the binder to prevent carbon black from reaggregating.

In order to optimize the dispersion process, the following measures can be taken:

Select appropriate dispersion equipment: According to the characteristics and dispersion requirements of carbon black, select appropriate dispersion equipment, such as sand mill, ball mill, high-speed disperser, etc.

Control the dispersion speed and time: The dispersion speed and time have an important influence on the dispersion effect. Generally speaking, the faster the dispersion speed and the longer the dispersion time, the better the dispersion effect. However, too fast dispersion speed and too long dispersion time may also cause carbon black particles to break or the system temperature to rise, affecting the performance of the product.

Adjust the pH value of the dispersion medium: The pH value of the dispersion medium also affects the dispersion effect of carbon black. By adjusting the pH value of the dispersion medium, the charge properties of the carbon black particle surface can be changed, thereby affecting the adsorption behavior of the dispersant on the carbon black surface.

4. Pay attention to the storage and use conditions of the dispersant

The storage and use conditions of the dispersant also have an important impact on its performance. Generally speaking, the dispersant should be stored in a cool, dry, and ventilated place, avoiding direct sunlight and high temperature. During use, attention should be paid to the order and method of adding the dispersant to avoid adverse reactions with other chemicals. At the same time, the quality and performance of the dispersant need to be checked regularly to ensure that it meets the requirements for use.