In the coating process, a coating is applied to particle surfaces to envelop and protect sensitive substances. Different properties can be achieved by this: Coating protects against oxidation, for example, and therefore increases the storage stability. The environment can also be protected against aggressive components in this way. Coating can also improve the pourability and dosability. It also covers up a negative smell or unpleasant taste which is important in the production of animal fodder.
The protective coating can do even more. It controls when the protected substances are released. The ingredients release their effects at the desired place at the desired time and can thus unleash their full impact. A certain mechanism is started depending on the chosen type of protection:
The water-insoluble protective coating becomes permeable or even dissolves at a certain place or time by a chemical reaction based on the principle of diffusion., The permeability of the applied coating is influenced, for example, by changes in the temperature, pH value or by the presence of specific trigger elements such as enzymes.
The coating material on the particle surface ensures that the active agents of the particles are released continuously. This reduces the frequency of intake or absorption of the coated particles because the active agents are released over a longer period of time.
inprotec AG as a contract coater uses the fluidized bed technology for the coating. The starting materials are fed into the fluidized bed for the coating process, swirled in the air stream and sprayed with film-forming liquids. In the spray coating or film coating in the fluidized bed, the film material is applied evenly as a surface coating. It is also possible to apply several coating materials one after another to the particle surface to achieve a so-called multilayer coating. Water-soluble and hydrophobic coating materials are available for coating:
- Watery solutions, suspensions or emulsions
- Melt emulsions or melt suspensions
The surface structure of the starting materials can be formed specifically with the process. Macroscopic particles with a particle size of 150–200 µm to 5 mm can be individually enveloped protectively in the coating process.
- Homogeneous distribution of the coating material
- Protection of the particles against external influences
- Protection of the particles against internal incompatibilities
- Protection of the environment against particles or active agents
- Specific controlled release mechanisms
- Controlled semi-permeable diffusion (slow release)
- Improved storage stability
- Particles suitable for tablet forming (direct compression)