Capsule formation
View Patent ↗A method and apparatus for forming hard shell capsule components, wherein the capsule components are formed from a material which undergoes gelation upon heating, such as HPMC. A heat station is provided to heat a plurality of molds prior to dipping into a solution of the thermogeling material. The drying conditions following dipping are carefully controlled to control the rate of drying.
1. A process for forming hard shell capsule components wherein said hard she capsule components are formed from a capsule material which undergoes gelation upon heating, comprising:
preheating a plurality of component molds to a temperature above the gelation temperature of said capsule material, by placing said component molds into an oven comprising a heat zone and a soak zone, wherein said component molds are heated in the heating zone, and allowed to achieve the preheating temperature in the soak zone, and further wherein the heating zone and the soak zone are located within the same oven;
dipping the preheated component molds into a solution of the capsule material; and
transferring the molds and their respective molded components to a drying station, wherein the drying station includes a first section in which the molds are subjected to a temperature ranging from 50-90° C. at a relative humidity of 20%-90%.
2. The process according to claim 1 , wherein the capsule material is a cellulosic material.
3. The process according to claim 1 or claim 2 , wherein the molded capsule components are retained within the first section of the drying station for 60-600 seconds.
4. The process according to claim 1 , wherein the solution of capsule material is maintained at a temperature of 25-35° C.
5. The process according to claim 1 , wherein the capsule material is dissolved in a solvent comprising water into which the molds are dipped.
6. The process according to claim 1 , wherein the molds are carried on a mold carrier.
7. The process according to claim 1 , wherein the molds are pre-heated to a temperature of 55-95° C.
8. The process according to claim 1 , wherein the molds are retained within the oven for 60-300 seconds.
9. The process according to claim 8 , wherein an array of molds is provided on a mold carrier and the oven is adapted to receive a plurality of mold carriers.
10. The process according to claim 9 , wherein the oven includes a cylindrical drum which includes a plurality of mold carrier retaining elements, carried on the inwardly facing surface thereof and each mold carrier is guided into a respective retaining element.
11. The process according to claim 10 , wherein the retaining elements are circumferentially spaced around the inwardly facing surface of the cylindrical drum, the drum is driven to rotate about its axis, and the oven includes a carrier element entrance port and a carrier element exit port, whereby an unheated mold carrier is guided into a respective carrier element of the drum via the entrance port, is heated in the drum as it rotates and is ejected from the drum at the desired preheating temperature when the mold carrier arrives at the exit port.
12. The process according to claim 1 , wherein the heating of the capsule component molds is applied with infrared emitters or radiators.
13. The process according to claim 12 , wherein the preheating temperature of the component molds is controlled by adjusting the energy output of the infrared emitters or radiators.
14. The process according to claim 1 , wherein the preheating temperature of the component molds is controlled by adjusting the length of time the component molds are retained within said oven.
15. The process according to claim 1 , wherein the components molds are exposed to a heated gas flow within the soak zone to allow the equalization of the desired preheating temperature.