MICRO-ENCAPSULATION

Science and technology

Micro-encapsulation has gained rapidly interest into a variety of industrial disciplines. One of the first industrial processes dates back to the 1930 years : the carbonless self copying paper : tiny micro-capsules filled with ink are fixed on the back side of the paper and crushed by the pencil when writing on the paper.

In general the micro-encapsulation technology is now well-spread in different application areas, the largest volumes are likely to be the fertilizer, detergent and seed industries.

At the time that a major market research house ( Frost & Sullivan 2002 ) writes “ whilst some of these areas are mature markets where micro-encapsulation has been used for many years, others are just starting to see the true benefits that these enabling technologies can bring to products. Micro-encapsulation will undoubtedly continue to find new and exciting applications “, the number of patents issued were about 1000/year. Only 5 year later this figure has doubled.

The majority of processes include a droplet separation step : either destined to form the shell, or to create the core form and size. In many cases the liquid phase is destined to solve the shell material for deposition around the core and is evaporated during the stabilization phase of the process. Other processes will favor gelling or crystallizing of the capsule wall.

The core can be in liquid or solid form, sometimes as a gas and should be totally surrounded by the shell to form a micro-capsule. A micro-sphere is a common description for the inclusion of a larger number of particles or droplets into a matrix, in most cases providing little protection but providing an agglomerate, which avoids dust circulation.