Powder/granule adhesives

Spheroidization and lubrication—In the first step, the entire bicone is tumbled to spheroidize the powder granules through abrasion and the adhesion of fine powder particles, further improving the powder flow behavior. In some processes, a lubricant is also added to enhance the flowability of the powder during future handling steps. 

EN 543 1995 Adhesives. Determination of apparent density of powder and granule adhesives. (Norme Frangaise T76-091). 

There are different delivery forms available soft hot-melt adhesives are preferably packed into compact blocks or cartons, while highly viscous hot-melt granules are usually powdered with line mineral powder such as talcum or silica to inhibit the clumping of the granules. This allows them to remain fit for storage. In contrast, as solid hot-melt adhesives do not form clumps easily, they are available in the form of powder, granules, or to some extent, sticks. Hot-melt adhesives also exist as films on release paper, winded into rolls. Such films can be precut into sheets, which are used immediately for mass productions, instead of being stored for later use. 

Often, a binding or adhesive granulating agent is required which may be added in solution or mixed with the tablet ingredients as a dry powder for subsequent activation by moisturing with an appropriate solvent. Many binders are hydrophilic colloids as, for example, polysaccharides (Table 5). 

Suspension polymerization also is used When acrylic monomers or their mixtures with other monomers are polymerized while suspended (usually in aqueous system), the polymeric product is obtained m the form of small beads, sometimes called pearls or granules. Bead polymers are the basis of the production of molding powders and denture materials. Polymers derived from acrylic or methacrylic acid furnish exchange resins of the carboxylic acid type. Solutions in organic solvents furnish lacquers, coatings and cements, while water-soluble hydrolysates are used as thickeners, adhesives, and sizes. 

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