Tell us about granulation. In fact, there are only two best forms of TGIC in the world, one is micronized to a particle size similar to that used in electronic inks, and the other is a hemispherical particle like the one pictured in the title. Although the story is a bit contradictory, but it is indeed the case.

TGIC from methanol crystallization according to the article (2) is mainly needle crystallization, but because of the crystallization of the stirring and faster cooling rate, the particles are often relatively fine, and the shape is not very regular. After the methanol is separated by centrifugation or filtering, the TGIC crystals that come out of the machine are agglomerated or powdered (with volatiles such as mother liquor and methanol). From this point on, each TGIC has its own drying process for final molding. For the sake of convenience, let's call it ABC

A The most primitive is the drying and pressing process, in which the above-mentioned TGIC crystals are placed in a rotating vacuum tank, and the volatiles are removed by vacuum while heating up. This powder is easily floated in the air due to the large number of fine crystals, and is highly allergenic, but not only in the manufacturing process of TGIC, then these powders are added to an extrusion granulator similar to a tablet press and pressed into continuous tablets by pressure.

The characteristic is that the pressed flakes are thick and tight, the later extrusion dispersion performance is not good, along with the transport extrusion appears more powder, very easy to float in the air caused by the operator's allergy.

B extrusion granulation after drying process. The pelletizer is similar to the extruder, in which the moist TGIC granules are continuously pushed out through the porous die head while the single or twin screws rotate and are cut into uniform lengths at the head to form fine, round particles. The moist cylindrical granules are then passed through the dryer for drying operation. Here the drying process is divided into the difference between atmospheric pressure and negative pressure.

B1 atmospheric pressure drying, generally with microwave drying drum and thermal cycle oven two, its drying products after the effect is similar. Microwave drying is more efficient to heat from the center of the pellet, and the heat cycle is less efficient to transfer heat from the outside of the pellet.

The characteristic is that the pressed pellets are compact, uniform in size and easy to mix in the premixing stage. The particle size is smaller than A. It is more suitable for the extrusion process where the mixing is not very good.

B2 negative pressure drying, on the basis of hot air circulation or heating plate will be made to dry the pellets under negative pressure. Drying temperature can be relatively low and more efficient.

The characteristics are similar to the popcorn effect of negative pressure drying, making the drying of pellets with internal voids. It ensures better extrusion dispersion with little dust. More suitable for poor extrusion conditions than B1.

C Melt granulation, the wet material of TGIC crystallization is first dried under negative or atmospheric pressure and then melted into fluid form. It is then granulated or flaked by a granulator or tablet press and cooled and hardened on a cooling belt.

The characteristic is that the cooling and hardening is a process similar to crystallization, and the better quality of the TGIC melt is the only one that can be hardened within a certain period of time. Therefore, these products are first of all excellent in chemical quality. Then the process is different so that the final product has very low dust content and the fine particles are also crystals after agglomeration, which are not easy to float in the operation site. The disadvantage is that these particles are very dense and require a high degree of extruder dispersion. The allergenicity of these products is lower with good extruder mixing.

D Micronized TGIC, different from the general use of granulation, TGIC crystals are dried and then further crushed by airflow crushing mill.

Characteristics It is very easy to disperse, and the best performance of the coating film can be achieved without too good dispersion equipment, but these products are easy to agglomerate and have poor storage performance. In addition, without reasonable environmental purification equipment, the floating very fine dust is very harmful to the operators on site. Some data show that 90% dosage after micronization can reach the normal curing level.

The above situation in the selection of TGIC you can consider the selection of the appropriate form of TGIC according to their own equipment and the characteristics of the final product.