Package making – Apparatus for forming or partially forming receptacle and... – Forming a pocket – depression – or hollow compartment by...
Reexamination Certificate
2001-11-02
2004-06-08
Sipos, John (Department: 3721)
Package making
Apparatus for forming or partially forming receptacle and...
Forming a pocket, depression, or hollow compartment by...
C053S140000
Reexamination Certificate
active
06745546
ABSTRACT:
TECHNICAL FIELD
This invention relates to an improved apparatus and method for producing ingestible encapsulated products, such as soft capsules filled with a liquid, suspension, solids, semi-solids, powders, tablets, medicines, nutrients and other materials. More specifically, the invention is directed to the use of melt-on-demand devices and extrusion dies to produce a ribbon of encapsulating film. The improved apparatus may also comprise a novel injection wedge.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 1,970,396 to R. P. Scherer describes an early method and machine for producing soft gelatin capsules in an automated process. The process involves the formation of two gelatin sheets or films through the use of a gravity fed spreader box, cooling the liquid gelatin on two separate webs, then lubricating and guiding the two sheets into communication with each other between two co-acting dies while simultaneously dispensing the proper amount of medicine or other filling material between the sheets in registration with half cavities in the outer surface of the dies.
U.S. Pat. No. 4,817,367 to Ishikawa et al. introduced some improvements to the basic machine to aid in the set up, operation and quality of the capsules produced, however, a gravity fed spreader box was still used to form the gelatin ribbons or sheets.
U.S. Pat. No. 5,761,886 to Parkhideh discloses an apparatus for forming capsules that provides rotary dies that are independently moveable and the ability to vary the speed of the dies during the formation of a single capsule. The Parkhideh device also utilizes independently controlled casting drums to reduce “set-up” time and provide better quality control. Even though Parkhideh discloses a very sophisticated encapsulation machine, it still utilizes a gravity feed spreader box for formation of the encapsulating ribbon. Other patents relating to encapsulation techniques which disclose the use of spreader boxes to create the film or ribbon on a casting drum include U.S. Pat. No. 5,246,638 to Ratko et al.; U.S. Pat. No. 5,735,105 to Stroud et al.; U.S. Pat. No. 2,774,988 to Stirn et al.; U.S. Pat. No. 6,022,499 to Schurig et al.; and U.S. Pat. No. 2,288,327 to Scherer.
One interesting reference is U.S. Pat. No. 4,028,024 to Moreland. It discloses a process and apparatus that prepares a gelatin encased medicament. The gelatin and the active are co-extruded as a column. This column is then pinched off by a pair of rotating wheels, each having half cavities therein to form capsules.
These previously utilized machines have many structural and operational shortcomings. Many of the shortcomings relate to the “set-up” of the machine. For example, the die to die timing, pump timing, ribbon formation and wedge adjustments are all important in protecting the equipment and providing a quality product. One aspect of the present invention resides in the use of a melt-on-demand extrusion technology and/or a valved wedge to decrease set-up time, reduce costs and improve product quality. The apparatus and process of the present invention allows for the use of encapsulating materials that were previously unusable on a standard rotary die encapsulation machine due to high viscosities or processing temperatures.
A general discussion of the basic technology, apparatuses and processes relating to the preparation of soft capsules is described in
The Theory and Practice of Industrial Pharmacy
(Lachman, Liberman and Kanig) 3
rd
edition, published by Lee & Febiger.
Conventional technology for the manufacture of soft capsules using the rotary die process typically utilizes a spreader box metering system to cast the films or sheets onto a chilled surface, i.e., the casting drum. The present invention differs from conventional technology by the method of producing the sheets, ribbons or films. In the inventive process, extrusion dies are used as an alternative to spreader boxes. Further, the film-forming composition is not kept molten but rather is allowed to solidify and only the amount needed is melted just prior to its placement on the casting drum. In addition, the novel valved wedge according to the invention provides economical set-up of the encapsulation machine.
The conventional process of producing gelatin films comprises mixing gelatin, plasticizers and water, and heating the mixture while stirring under vacuum. The gelatin and excipients are heated under vacuum with mixing until a molten homogenous mixture is produced that is referred to as a gelatin melt. This occurs at approximately 45-65° C. The molten system is drained into heated tanks that maintain the gelatin in a molten state during staging and casting of the films. Staging can be as long as two to three days. Before encapsulation, other additives such as colorants, preservatives, sweeteners, flavors, texture modifiers and the like may be blended into the gelatin melt.
During the prior art encapsulation process, the molten gelatin melt is transferred to the metering devices (spreader boxes) which are used to cast ribbons with a required thickness onto the casting drum. Commonly, the metering device consists of a heated reservoir that uses a gate box (a heated chamber or box with the rear portion fitted with a variable height slot) wherein the material flows via gravity through the slot onto the rotating casting drum. Film thickness is determined primarily by the height of the slot. Item 8 in Parkhideh, U.S. Pat. No. 5,761,886, is a spreader box. A second type of metering device meters the gelatin onto the rotating casting drum using doctor blades. A rotating cylinder mounted adjacent to the doctor blade assists with the flow of the gelatin. Ribbon thickness is determined by a) the gap between the doctor blade and the casting drum surface; and b) the speed of the spreader box cylinder. The cast ribbon solidifies onto the rotating casting drum after leaving the spreader box and this can take up to 10 to 15 seconds to achieve. The typical spreader boxes are vented to the atmosphere and are not capable or designed to support pressure to facilitate the casting process.
U.S. Pat. No. 2,775,257 to Stim et al. discusses some of the shortcomings associated with the prior art gelatin film casting machines. This reference describes the use of casting hoppers where it has been found that the surface of the gelatin composition exposed to the air lost moisture by evaporation and formed a comparatively hard, inflexible scum or skin. Additionally, changes in the gelatin composition introduced by the evaporation of moisture from the surface caused undesirable variations in the film. Stim et al. found that by placing a layer of an inert liquid, such as mineral oil, on the surface of the gelatin composition, evaporation from the hoppers was prevented. This reference also provides a fairly good description of the use of a casting hopper or spreader box to form the ribbons.
In the prior art process, transfer of molten gelatin from the holding tank to the metering device (or spreader box) is achieved in one of two ways. A common method is to suspend or mount the tank of molten gelatin above the encapsulation machine and allow the molten material to gravity feed through heated tubes into the reservoir of the metering device. Another transfer method conventionally used is to pump the molten gelatin via heated tubes from floor mounted gelatin staging tanks using either a peristaltic or lobe pump system. One shortcoming of the pump feed system is that the pump casing/components and in-line connections must be maintained above the melting point of the film-forming composition. If there are cold areas within the path, the material will freeze and prevent flow. In addition, both gravity and pump systems require a method of controlling flow to prevent overfilling of the spreader boxes.
The conventional process also relies on maintaining the gelatin melt in a molten state from initial manufacture to just before encapsulation. Tanks used to feed the encapsulation machine require the entire tank to be maintained above the melt temperature of the film-formin
Tanner Keith
Waranis Robert P.
Huynh Louis
Nickey Donald O.
R.P. Scherer Technologies, Inc.
Sipos John
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