dripping

Specification

Principle of technology

Dripping is the simplest particle formation

Principle of technology

Dripping is the simplest particle formation technique we use. It involves a precursor liquid passing through a nozzle of appropriate diameter, then being broken into equally sized droplets by gravitational forces. The droplets are further processed to form particles by cross-linking or polymerization (hardening process) of the precursor liquid. It is a requirement of the technology that the hardening process is very fast in order to achieve optimal particle quality. If no such fast hardening process is feasible, e.g. in cases where the hardening process is based on radical polymerization, the dripping technology has to be combined with other technologies such as preeTec’s proprietary tandem process, or a two phase system process. Dripping technology gives a very narrow bead size distribution. However, the volumetric flow per nozzle is limited and the size of the resulting particles can only be controlled within a narrow range.

Materials that can be processed

• Alginate: hardened by crosslinking with bivalent metal ions; alginate particles can be further processed to result in coated particles as alginate-polylysine-alginate, alginate-polyethylenimine or multiply coated systems
• Carrageenan: hardened by crosslinking with mono or bivalent metal ions and / or thermal gelation
• Pectinate: hardened by crosslinking with trivalent metal ions
• Agarose: hardened by thermal gelation
• Cellulosesulfate: hardened by PDADMAC
• Chitosan: hardened by crosslinking with polyphosphate
• Acrylamide and other acrylic monomers: hardened by radical polymerization; combination with tandem process or two phase system is mandatory
• Waxes and paraffin: hardened by thermal solidification

Application examples

• Slow release of antimicrobial agents in liquid products
• Implantable immobilized enzyme biosensor systems
• Sorption of environmental contaminants

Superabsorbent polymer (SAP) Beads made from modified acrylics with a very low size distribution (mean size 1.8 mm; sdev 0.01mm) produced by dripping method in a two phase system.