Binder distribution

Another major function of the starch is to increase the waterholding capacity of the coating. This reduces the tendency for the binder system (there is usually a cobinder present) to migrate excessively during the high-temperature drying process. Any alteration in the binder distribution within the coating can drastically affect the appearance and performance of the coated sheet. 

Increase collision frequency subsection.) Increase binder distribution. Increase mixer impeller or drum rotation speed or fluid-bed gas velocity. 

There are conflicting reports on the preferred method of adding the binder. For example, Holm does not generally recommend adding dry binder to the mix (as commonly done in order to avoid preparation of a binder solution) because homogeneity of binder distribution cannot be assured. Others recommend just the opposite. " " ... 

Reynolds G, Biggs CA. Salman AD. Hounslow MJ. Non-uniformity of binder distribution in high-shear granulation. Powder Tech 2004 l40(3) 203-8. 

Rate of growth (low deformability) Increase rate of nuclei formation. Increase collision frequency. Increase residence time. Improve wetting properties. (See Wetting subsection.) Increase binder distribution. Increase spray rate and number of drops. Increase mixer impeller or drum rotation speed or fluid-bed gas velocity. Increase batch time or lower feed rate. 

Chemistry, wetting characteristics Binder distribution Nozzle position/spray... 

Compared to conventional spray processing, FBT can shorten processing times by reducing water requirements. It can improve reproducibility through more uniform binder distribution. Moreover, it eliminates spray nozzles and their many variables in granulation processing equipment. Foam processing also offers better end-point determinations and reduced equipment clean-up time. 

Clearly, control of rheological properties of coating colours is desirable, and this is achieved through polymeric additives. The aim is not only to favourably adjust the viscosity and other rheological parameters of the suspension per se, but also to improve the water retention properties of the colour. If the suspension dewaters too quickly before or on application, this can lead to severe runnability problems, such as the formation of streaks, dry stalagmites and uneven binder distribution. 

Lewis, J.A., Boyer, M., and Bentz, D.P. (1994) Binder distribution in macro-defect-free cements relation between peicolative properties and moisture absorption kinetics. 

As outlined previously, wetting is the first stage in wet granulation involving liquid binder distribution to the feed powder. There are two extremes (1) liquid drop size is large compared to unit or primary particle size of the feed and (2) particle size is large compared to the drop size. 

Watano et al. (1994) Lactose and cornstarch with water Hybrid fluid bed with agitator Drop size, binder distribution... 

Improve wetting properties (see Wetting subsection) Increase binder distribution... 

Polymer Concentration. The effect of cellulosic polymer concentration on granule properties is dependent on their method of addition. In the wet addition method, increasing the concentration of HPC, different viscosity grades of HPMC and MC in lactose-cornstarch-microcrystalline cellulose systems increases the percentage of binder-rich oversize granules (61). The effect can be attributed to the increase in binder solution viscosity and heterogenous binder distribution. 

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