Our patented microsphere manufacturing technology is of great help if one wants to produce spherical granules from 50 micron diameter to over 5 millimeter diameter from varying materials. Our technology is applicable to nearly any material that can be liquefied, suspended, or melted and solidified again afterwards.

The liquefaction of the starting material can be achieved by different means:
the dissolving of the raw material in nearly any solvent chosen (this process is called a binder process because a temporary binder is often used), the melting of the raw material in a melting furnace (melting process), or the generation of a gel from a sol (SOL-GEL process).

For the production of microcapsules, a combination of these processes is often used.
 

One of the commonly used processes for the production of spherical granules is based on the application of a (temporary) binder which agglutinates the particles of the starting material, which often is an organic or inorganic powder.

A binder is e.g. used for the production of granules from inorganic oxides like ZrO₂, HfO₂, SiO₂, Al₂O₃ etc.
The binding agent is usually an organic substance like alginate, gelatin, agar-agar, cellulose or an inorganic sol like SiO₂.
The organic or inorganic binders are removed from the resulting microspheres by a slag process with temperatures of about 300° C. It is possible to produce microspheres with hardly any impurities with these simple and versatile processes. According to the starting material many different microspheres can be produced: grinding beads with a very high density, catalysts and catalyst supports, additives for food or cosmetics and so on.

Binder processes can also be used for the encapsulation of mammalian cells for medical purposes and for the encapsulation of aromas and perfumes for food, cosmetics and other consumer goods.

We offer as standard products some of the frequently requested products like ceramic microspheres, catalyst supports and microspheres for cosmetic applications.

We are involved in developing new recipes in cooperation with its customers for the production of microspheres specifically for the customer application.
 

The production of microspheres by a melt process is based on the change of state (solid to liquid) of the starting material by temperature. That's why this process can only be applied to materials that can be melted. Besides, materials that can be melted also have to have a viscosity that is sufficiently low.

Viscosities of about 10 mPa*s are optimal but nearly any material with a viscosity up to 200 mPa*s can be processed in this manner.

According to the features of the starting material it is also possible to process materials with a viscosity up to 10,000 mPa*s.

But one has to keep in mind that the smallest diameter of the microsphere is correlated with the viscosity of the molten starting material: the higher the viscosity, the larger the minimum sphere diameter.
The temperature for the production of microspheres by melting processes is limited only by the starting material itself; so it is even possible for us to process pure silicium at 1450° C.
 

If a metal ion has an oxide with a low solubility, this oxide can be precipitated from a pre-neutralized solution by the addition of a base. In this reaction, the metal ion hydroxide is formed which passes over into the oxide. In the meantime, the viscosity of the solution increases. Therefore, this process is called the formation of a gel from a sol.

The SOL-GEL process is used for the production of extraordinarily pure oxidic microspheres, e.g. for the production of Al₂O₃ microspheres.

These microspheres are precipitated from the solution instead of by adding a binder to it. Therefore, it is possible to produce extraordinarily pure microspheres with a very large surface area.

The SOL-GEL process can also be applied to the production of catalysts, catalyst supports and nuclear fuels which must not be contaminated.
 

Each process previously described can also be applied to the production of microcapsules with our double nozzle systems.  These are shell and core microencapsulates.

Microcapsules are produced with special double nozzles that produce two concentric droplets at the same time. The material in the inner core can be chosen independently from the shell material unless it weakens the stability of the shell.

The shell material, on the other hand, can be chosen to be a solution, a molten mass, a sol, or a combination of these.

The hardening of the spheres is done as described for microspheres. The result is a capsule with a solid shell and a solid (if a molten mass is used for the inner core) or a liquid core.

Materials that are encapsulated are as varied as the industries within which they are applied and include:  aromas, anti-allergic substances, controlled release or sustained release drugs, consumer care beads, flavors, acids, caustics, textile actives which have to be protected, phase change materials, etc.. Such capsules are needed e.g. by the food, textile, agricultural, pharmaceutical, chemical process, nutraceutical, and the building industries

.
Microcapsules are extraordinarily stable. The encapsulated substances can be released at once (e.g. if pressure is applied to the capsule or the shell material is dissolved) or little by little (which is wanted for long-term effects of pharmaceutical controlled or sustained release substances which are released by pH changes). Moreover, it is possible to encapsulate substances stably, like phase change materials.

If binders such as hydrocolloids are used for the production of microcapsules, drying can be helpful. Because commonly used dryers, like heating chambers, fluidized bed dryers, or microwave dryers are not suitable for this purpose, we have developed our special drum dryer.

I