Coating Place has been Wurster coating since 1976, so we can guarantee optimal services that meet your capacity, efficiency, and quality needs.
Wurster fluid bed contract manufacturing services are the foundation of Coating Place business. The Wurster process is recognized as the technology for precision application of a film coating onto particulate materials such as powders, crystals, or granules, and other solid ingredients with diameters ranging from 30 µm to several centimeters. Although Wurster technology was originally developed for the pharmaceutical industry, it can be used in a variety of industries. Coating possibilities are almost unlimited, including the ability to place a hydrophilic coating on a hydrophobic core, or an aqueous coating on a water-soluble core. Film coat properties or product performance can be optimized with changes to coating formulation, processing conditions, or use of multiple coat layers.
Film coating processes require evaporative removal of an aqueous or organic solvent as the film is deposited. The speed of a film coat application is related to the drying capacity of the process. Fluid bed film coating processes have a greater drying capacity than other coating systems due to a relatively high fluidizing air volume that is used to both circulate particles and evaporate the coating solvent. This increased drying capacity translates to more efficient film coating applications.
Wurster technology is characterized by the location of a spray nozzle at the bottom of the fluidized bed. The particles are moved with a fluidizing air stream that is designed to induce a cyclic upward flow of particles, past the spray nozzle. The nozzle sprays atomized droplets of coating solution or suspension concurrently with the particle flow, depositing droplets on the surfaces of the particle as they pass upward into an expansion chamber. This expansion chamber reduces air velocity to allow particles to circulate back to the coating chamber. It also allows particles to temporarily separate from one another, minimizing the potential for particle agglomeration and accretion. Organic or aqueous coating solutions evaporate as the particles move into and through the expansion chamber, leaving non-volatile coating formulation ingredients on the particle surface as part of the developing film coat. Process parameters are designed for optimal solution evaporation and film coat characteristics. This batch process is continued until each particle is uniformly coated to the desired coat percentage or film thickness.
In a similar fashion, the Wurster fluid bed process can be used to apply a hot melt coating, such as wax. Wax is heated to a molten state and sprayed in the same manner as a solution suspension. Process parameters are adjusted to congeal molten wax droplets on the surfaces of the circulating particles.