| abstract |
A process for preparing free-flowing and during handling dust-free micro-particles,nat least 90% by weight having a diameter of 100-400 µm, containing one or more activeningredients in a glassy matrix, using a multi-stage spray drying unit, by forming annaqueous solution which contains on solid basis from 40 to 70 % by weight of at least onenlow molecular weight carbohydrate and/or polyhydroxy compound and 30-60% by weightnof at least one high molecular weight film forming agent, whereby the aqueous solutionncontains at least 50% by weight of said agent(s); incorporating at least one activeningredient into the solution and building an emulsion or suspension, whereby saidnemulsion or suspension contains on aqueous basis between 1-35% by weight of the activeningredient(s); spray drying the emulsion or suspension into a spray drying tower at an airninlet temperature of 100-180°C and an air outlet temperature of 60-95°C; transferring to anfluid bed section the resulting surface dried semi-solid micro-particles having a waterncontent of about 10-20% by weight and having a particle size of about 10-200 µm andncontinuing drying and simultaneously agglomerating said micro-particles at an airntemperature of between 25°C and 55°C resulting in solid, free-flowing particles with anglassy matrix having mainly a size of 400 µm or lower and having a water content of aboutn2-6% by weight; collecting the particles, at least 90% by weight of that particles having ansize in the range of 100-400 µm and a water content of 0.5-4% by weight and recycling thenparticles having a size mainly below about 100 µm from the fluid bed either into the sprayndying tower to allow growth of these particles by wetting the particles with fresh sprayed innemulsion or suspension or to the upper part of the fluid bed to allow growth of thesenparticles by agglomeration to a size in the range of 100-400 µm. |