Nowadays, the process technology of soft capsule has been relatively mature, and there are various automatic solutions. The main process flow of soft capsules is: ingredients - sol - pelleting.
Different drugs should be formulated differently base on its own chemical and physical characteristics.
For the oil type drug, it is just required to add the right amount of bacteriostatic agent, or add a certain amount of PEG400.
For the solid type drug, firstly smash it through a 100-200 mesh sieve, then add PEG400, grind it by colloid, or mix it with low-speed stirring and glass sand to make the drug evenly suspended in the solution in the form of fine particles.
Gelatin, glycerin and water are the main force of soft capsule, the proportion is generally gelatin: glycerin: water=1:0.3-0.4: 0.7-1.4. After being proportioned, adding to the sandwich tank, stirring and heating to melt it, then keeping it warm for 1-2 hours. After the foam floats up, keep warm and filter it to a sol type.
The Pelleting process turns the sol to soft capsule, which is the core process of soft capsule manufacture. There are generally two methods, dropping and pressing.
1.) Dropping- Adding the oil and sol into the dropping machine hopper and maintained with a stable temperature. Placing the non-harm cooling liquid in the soft capsule, adjusting the discharge port base on drug content of soft capsule, after this, dropping the oil and sol in different speed. Normally, the gelatin drops onto the liquid paraffin, and the oil is immediately drops on the surface of the gelatin which has just been unfolded, then the gelatin naturally forms, when the gelatin completely sealed the oil inside, the capsule shape will be in oval due to the surface tension, this method is suitable for laboratory soft capsule need due to slow process speed and low-cost driven.
2.) Pressing-Turning the sol into sol tape by pressing machine, placing the drug solution between two sol tapes, adjusting the thickness of sol tapes then directly pressing drug and sol tapes together with steel mold. This method generally uses a continuous rotating steel mold. Two sol tapes line up different side and joined at steel mold. The drug solution entering the tape by filling pump and pressed all together by the steel mold. This method is suitable for mass production because of 3H (high speed, high automation and high yield).
After the pelleting process, shaping the soft capsule by dynamic air drying in the dryer cage, which generally lasts 4-6 hours.
Scrubbing the soft capsule surface is required during or after the shaping process. If the latest micro-oil lubrication process is applied, then only mild scrubbing needed during the shaping process. If the capsule requires the customized printing, then polishing it as well after scrubbing to enhance the clarity of print.
Drying improves the shape and touch feeling of soft capsule, the normal procedure is static drying by dry tray or dynamically air dry in a double-layer dryer, the drying process usually takes 12 to 16 hours to keep the moisture content of the soft capsule shell reaches 8%-12%.
After that, it is the process of sorting, packaging, etc. These processes are based on product demand so we will not discuss in this article further more.