Plastic masterbatch belongs to the middle link of the plastic products industry. It is the downstream of pigments and petrochemical products and the upstream of plastic products. It has an important role and position in the plastic products industry.

Why is the dispersion of plastic masterbatch good?

The good dispersibility of the plastic masterbatch means that the pigment is fully dispersed in the plastic to the ideal particle size and mixed evenly in the plastic. The complete pigment dispersion process usually contains three essential stages.

1. Wetting The interface between the pigment and air or water becomes the interface between the pigment and the vehicle.

2. Dispersion The pigment particles break particle agglomerates and aggregates under external force.

3. Stability Stabilizes the pigment particles that have been dispersed in the medium and effectively prevents re-agglomeration.

The important step of pigment dispersion is the wetting of the pigment particles, which is divided into the initial wetting of the pigment and the continuous wetting of the fine particles during the dispersion process. For plastics processing, initial wetting is the process in which the resin vehicle replaces the air and moisture on the surface of the pigment. The purpose of pigment wetting is to reduce the cohesion between the pigment particles. If the pigment surface cannot be completely loaded The body (which also contains a wetting agent) is wetted, then the shear stress generated by the dispersing device through the melt medium has no effect on the pigment agglomerates. The difficulty of pigment wetting is determined by the surface properties of the pigment particles and the properties of the color vehicle. The smaller the contact angle between the pigment and the vehicle, the smaller the surface tension of the vehicle, and the easier the wetting.

The second step of pigment dispersion is the refinement of the pigment particles. After the pigment particles are wetted, the process of pigment micronization is completed under the action of external force, and the pigment is crushed and refined to the desired particle size. At present, the external force of mechanical dispersion is nothing more than pressure, impact force and shear force to pulverize agglomerates and aggregates of pigments.

The third step of pigment dispersion is to stabilize the dispersed pigment particles. The surface area of the refined pigment particles will increase, which will cause re-agglomeration. The refined pigment particles will be further surface treated to reduce the newly formed interface. Surface energy in order to prevent the refined pigment particles from agglomerating again during further processing.

The pigment dispersion process described above, namely: wetting, refining, and stabilizing after refining, are inseparable and occur almost simultaneously in actual operation. They are discussed separately only for the convenience of discussion.

The initial wetting of the pigment has irreplaceable significance for the result of the pigment dispersion. Usually this process is completed through some seemingly simple steps, so it is very easy to be overlooked. However, the initial wetting is not only the wetting of the surface of the pigment particles, but the success or failure of the dispersion of the pigment particles starts from this step. The initial wetting is not done well, and the good dispersion of the pigment particles is impossible to talk about. The reason is Yes: The color vehicle resin must have sufficient capillary penetration between the microscopic gaps in the pigment particle aggregates. Due to the capillary penetration, the cohesive force between the pigment particles is reduced, and it is easily crushed and refined under the action of shearing force. Therefore, the pigment wetting rate and the degree of capillary penetration play a decisive role in the overall dispersion rate and quality of the pigment particles.　

 Countless practices have proved that most of the reasons for the poor dispersion of pigment particles are due to the imperfect initial wetting. When this happens, it is difficult to achieve the desired effect no matter what dispersion method is used to remedy the situation. At this time, Only by re-wetting the pigment particles can the dispersion problem be solved. Under the premise of using a common wetting agent for wetting, the final dispersibility of the same pigment is not satisfactory whether it is extruded and granulated once or for six times; but using a suitable wetting agent for the same Processing, the result will be a qualitative leap.