Moisture In Film Printing

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7. Water evaporation rate and moisture effect: Water evaporation rate is most important factor during aqueous film coating. The energy needs for evaporating aqueous medium are much higher than that for organic solvents. The film formation can occur by different mechanisms, based on whether the polymer is dispersed or solvated in an aqueous media. The rate of water loss will impact both the efficinecy of the coating process and ultimately, product performance. Moisture can influence the properties of polymeric coatings. The aqueous film- coating process have the effects of water, due to the possible entrapment of water in the micro domains of the film. Moisture in a film coating reflects effect of plastisizer on the polymer31-33. 1.8.4.3.…show more content…
1. Temperature: As the inlet air temperature increases the drying rate also increases and vice versa. This approach to increase the drying rate can not be used always because some materials are sensitive to high temperature, e.g. Ibuprofen get liquefy above 60°C temperature of inlet air should be optimized without harming product quality. If temperature is higher, it leads to blistering. If temperature is low, soft spot can be formed. Temperature also plays important role to improve coating efficiency. 2. Humidity: Humidity in the inlet air should be as minimum as possible and dehumidified air should be used for faster drying rate because the rate of drying increases as the humidity of inlet air decreases. 3. Air flow rate: The rate of air flow should be controlled properly in order to get effective use of drying air. As the flow rate of air increases, the drying rate also increases and the cost of drying also increases. If drying air is kept in contact with the drying material, a proper heat transfer and mass transfer takes place and thus drying cost decreases. Air flow rate should be optimum for efficient drying. 1.8.4.4. In coating…show more content…
Spray pressure: Atomization of the coating solution depends on the pressure of a spray, thus for proper atomization droplet size should be developeed. Miscellaneous: 1. Moisture should not be present in case of hygroscopic materials. Moisture content can be controlled by using dehumidifier. 2. Method used for coating should be based on the purpose for which it is used. Eg. Sustained Release, Extended Release, etc. 3. Time of drying should be determined on bases of the product and quality of the coat desired. 1.8.5. Product parameters: A. In drying process: 1. Initial moisture content of material should be less to avoid increase in drying time. 2. Batch size- It should be optimum based on occupancy of equipment. B. In coating process: 1. Coating agent. Coating agent should be selected according to type of coating required e.g. enteric coating, sugar coating, delayed coating etc. Solvent should be selected according to the characteristics of the coating agent. 2. Starting material: Dimension of tablets greatly affects the coating process. In powder coating the particles size, shape and density affects the coating process. 1.9. Drug selection criteria for oral modified release drug delivery systems:

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