1. Field of the Invention
This invention relates to a method for preparing granules having a uniform granule size, good disintegrating properties, relatively great apparent density and abrasion resistance by subjecting a crystalline sugar, a basis, adjuvants and a binder-containing solution to a mixing apparatus, whereby the crystalline sugar is coated with the basis and adjuvants to form granules of a uniform particle size.
2. Prior Art
In general, granule or particle products have been heretofore prepared by powdering raw materials such as a basis and some suitable adjuvants, mixing the powdered material with a corrigent such as powdered sugar under wetting conditions, and granulating the mixture by means of an extruder-type or crushing type granulator.
The just-mentioned prior-art method is, however, defective in that: (1) The yield of the granule product becomes low due to substantial loss of the powdered material in the binding stage and, if a binder is used in a larger amount so as to raise the yield, the ultimate granular product will be deteriorated in disintegratability and solubility; (2) It is difficult to produce granules of uniform size and relatively great apparent density, and the commercial value of the products is lowered due to undesirably wide distribution of granule sizes and inconveniences in handling; and (3) A great number of production steps and manual operations are required, causing frequent operational troubles.
In order to overcome these defects, many improved methods have been proposed by introducing new apparatus of different types, including the method using a fluidized bed granulation apparatus and the method of coating core material with a sprayed suspension with use of a coating apparatus. However, the last-metioned coating method has a vital disadvantage that it requires a solvent in such a large amount that may spoil the working conditions with increased possibility of risky accidents, such as fire, explosion and the like, and also may give rise to environmental pollution. In addition, an enormous cost is required for installation of the facilities for collecting the solvent in order to prevent environmental pollution. Moreover, the spraying method has also the disadvantage that it is difficult to coat the core material completely with a powdery material. This results in reduction in yield and undesirably requires provision of a fine powder-collecting apparatus. Furthermore, the coated material is easily excoriated from the ultimate product even by slight friction, such as, for example, that occurred by sieving, due to insufficient binding between the core material and the coat, thus spoiling the commercial value of the product.