Scherer method
The Scherer process is a technical process for the production of capsules .
Various processes exist for the production of capsules, including the Accogel process , the Norton process and the Globex process . The Scherer process was developed in 1933 by the company founder Robert Pauli Scherer (1906-1960) and is alternatively known as the Rotary Die process (rotating roller process). It is used in particular in the manufacture of soft capsules.
In the following, the production of capsules in the course of the Scherer process is explained and finally reference is made to the associated advantages and disadvantages.
Manufacturing
In this process, the encapsulation takes place fully automatically and with the help of counter-rotating forming rollers. With this method, the capsule is continuously formed, filled and sealed in one operation. The gelatin melt is applied from the left and right onto a rotating cooling drum. By cooling from 60 to 70 ° C to room temperature, the previous sol state of the gelatin becomes the desired gel state, with the result that two endless gelatin strips are created. The gelatine ribbons are coated with an oil film so that they do not stick to the rollers and impair the further course.
After the flat strips, which can differ in their color, have cooled down, they are passed between two counter-rotating forming rollers. The filling wedge with heating elements located above the rollers fills the capsules.
The filling material is dosed by a dosing pump, which conveys the filling material under pressure and in bursts onto the rollers. Meanwhile, the lower and side parts are welded, so that a pocket-like cavity is formed between the two rollers, which is filled before the upper side is also welded. The welding of the side and top parts is coupled with the punching.
The typical result of the Scherer process is a visually perceptible seam on the long side.
The capsule can be caught in a capsule washing device, in which the oil film on it can be washed off. The capsule should then be dried in a drying drum to set, since the capsule shell contains a high proportion of water and is therefore still very soft and elastic.
After the capsule is stripped off, a gelatin ribbon with punched holes remains, which can be melted down again and used again for production.
The gelatin ribbons themselves can have different colors. This process can also be used to produce capsules of various shapes and sizes on a large scale and with precise dosing.
Advantages and disadvantages
- The Scherer process is a continuous process and allows the manufacture of a soft capsule in just a single operation.
- With this process, an hourly output of 100,000 capsules can be achieved.
However, there are also disadvantages to this procedure:
- The production of the capsules is expensive and prone to failure, since the forming rollers have to work very precisely, so that the economic content of the process, despite the high quantitative output, has to be examined critically.
- All rooms in the packaging and manufacture of the soft capsules must be air-conditioned accordingly.
- The gelatin tape with punched holes cannot be completely recovered either, because it has been coated with release oil.
- Likewise, the capsule shells contaminated with the release oil must be labor-intensive and cost-intensive to clean with the aid of suitable solvents.
literature
- Bauer: Textbook of Pharmaceutical Technology . 8th edition. Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart .
- Voigt: Pharmaceutical Technology . 12th edition. German pharmacist publisher .