Encapsulation and coating

Teunou and Poncelet (2002), in their extensive review of fluidized bed coating, identify three geometries for continuous processing. First, the monocellular bed which is essentially the type of equipment used 

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An important part of this work is the selection of the right material for encapsulating and coating. They have to be neutral in taste and they need to be approved and safe for food use. By choosing the right materials one can also achieve a better control over the release of the flavour, with the trigger being temperature, pH or the solvent used. 

Until recently, most silicone gels provided inadequate adhesion to coated or encapsulated parts. Modern silicone encapsulants and coatings contain, however, silane "coupling agents", which are able to form a permanent water proof covalent bond to most substrates and therefore avoid failure associated with loss of adhesion to the substrate. 

Fig. n.l3 Depiction of the formation of either a dense or porous capsule during encapsulation and coating processes [11.9]... 

Nonelastomeric Thermosetting Polyurethane Curable mixtures of isocyanate prepolymers or monomers. Has good abrasion resistance and low-temperature stability, but poor heat, fire, and solvent resistance and weather-ability. Processed by reaction inj ection and structural foam molding, casting, potting, encapsulation, and coating. Used in heat insulation, auto panels and trim, and housings for electronic devices. 

Tahcoat, Siloxane polyimide encapsulants and coatings, Ablestik Laboratories... 

The processing step involved simply the compression of the exposed layer to rupture the cyliths and developer capsules and squeeze out the contents. The amount of leuco dye released depended on the degree to which the cyliths were hardened. Image dye was then produced from the leuco forms by the action of developers [51]. In the most compact formats of the system, the developer were encapsulated and coated in the same layer as the cyliths. The system did not reach the necessary quaUty/permanence/cost criteria to make it commercially viable in the longer term and so it remains a clever curiosity and unfortunately another imaging blind alley. 

SnJCONE PROTECTIVE ENCAPSULANTS AND COATINGS FOR ELECTRONIC COMPONENTS AND CIRCUITS... 

Are the components of the formulation chemically compatible with the substrate being encapsulated and coated ... 

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