Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
1998-11-13
2001-08-07
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C424S464000, C424S470000, C424S458000, C424S490000
Reexamination Certificate
active
06270801
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of particle processing including producing and/or processing granules, pellets or other particulate materials by granulating, coating, encapsulation or layering operations.
Various types of equipment and processes are commonly used, or have been suggested, to produce granulae from fine particulate materials and also to perform the other above specified operations on particulate materials.
Examples of apparatuses constructed for said purposes are the following: High-shear mixers, planetary mixers, drums and similar apparatuses having a tumbling effect, stationary or vibrated fluidized beds, and apparatuses characteristic in having a rotating disc at the bottom of a chamber and means for providing a gas flow through an annular slot between the disc and the chamber wall.
This last mentioned type of apparatus exists in two different embodiments, viz. one in which the particulate material is kept fluidized in a gas stream while it is subjected to the influence of the rotating disc, and one in which fluidization is avoided to obtain maximum control between the particles.
To create granulation, the surface of the primary particles to be granulated is wetted by spraying an atomized liquid onto the particles. Said liquid can be a solvent or a solution which in contact with the particle surfaces imparts a certain stickiness to the latter, or it can be a melt having the same capability. Alternatively, the particle surfaces can be wetted by condensation of vapour, such as steam, thereon.
The same applies to powder layering processes where the surface of particles, which can be primary particles, granulae or pellets, is wetted to make the surface thereof adhesive so that injected fine powder sticks thereto.
The granulation process and the characteristics of the product obtained thereby depend on various features among which are the following: The wetting process, the amount of mechanical compaction to which the materials are subjected, the influence of attrition to the particles during the process, and the degree to which the particles are in mutual contact during the process.
The above mentioned various types and embodiments of apparatuses for performing the operations in question all provide different conditions as to said specified features. Consequently, for any specific purpose a specific apparatus type among the above mentioned will normally be preferred.
For certain operations within the pharmaceutical area and also in certain branches of the food and refreshment industry preference is often given to apparatuses of the last mentioned of the above types, that is apparatuses which as main characteristics have a rotary disc in the bottom of a processing chamber and means for providing an upward gas stream through the annular space or slot between the disc and the walls of said chamber, said gas being provided in an amount less than the one which would cause fluidization of the particulate material being treated. Especially for producing pellets by layering powder onto particles that type of equipment is regarded as superior to the rest of the above exemplified apparatuses, and the present invention deals with such an apparatus.
BACKGROUND OF THE INVENTION AND REVIEW OF PRIOR ART
Related apparatuses are known. Thus EP 228633 B1 to Aeromatic AG discloses an apparatus termed Roto-Processor™ which has two treatment zones, an inner zone surrounding the rotating disc and an outer fluidized bed zone. Such an apparatus is used for several purposes, for example wet granulation pellettizing where a starting powder is granulated with water or binder solution and, if reuired, subsequently dried in the fluid bed zone, or for coating by spraying a liquid onto core material where several layers of coating can be applied using either the same or different coating liquids. The apparatus can also be used for layering from liquids where a starting product, e.g. inert cores, crystals etc., is being sprayed with an active substance dissolved or suspended in a liquid which liquid is simultaneously dried. Pellets can also be formed by layering from powders where a substance is added as a powder and is bound to the surface of cores or pellets by simultaneously spraying a liquid binder and subsequently or simultaneously drying the resulting pellets.
Another apparatus and a method for producing pellets by layering powder onto particles are disclosed in EP 505319 B1, where liquid and powder are introduced into the particle layer on the rotating disc by means of a nozzle protruding slightly into the zone above the disc.
A similar apparatus is disclosed in EP 526394 A2, which is specially designed for melt coating of particles.
Various auxiliary devices for these types of apparatuses are known. According to U.S. Pat. No. 4,556,175 the apparatus is supplemented with an agitator and in U.S. Pat. No. 4,623,098 furthermore a disintegrator is included.
EP-608844 A1 also deals with a method and an apparatus of the type in question for powder layering and is concerned with the adjustment of the relative amounts of liquid and solids in the process. According to the specification baffle means can be provided to the inner wall of the granulating vessel or the rotary disc for helping tumbling and fluidizing of the material being treated. The specification also mentions the possibility of introducing gas for drying through a portion of the side wall of the granulating vessel.
In the apparatuses in question the material to be treated is kept moving by a combination of mechanical force and gas flow. The material is propelled by the friction which exists between the rotating disc and the material. When the material gains velocity by the shear force in the disc's rotary direction, it will be moved in the direction of the chamber wall by the centrifugal force.
The processes: Granulation, powder layering and coating all demand wetting of the material, and it is essential for the achievement of a uniform product having the desired characteristics as to particle size, particle size distribution, physical strength, solubility etc., that the wetting process is performed very evenly on all particles forming the material. The wetting is usually made by atomizing a liquid by means of a two-fluid nozzle using a pressurized gas, e.g. pressurized air. It is, therefore, important that the material can be moved around inside the chamber in a controlled manner so that each part of the material passes the spray nozzle substantially the same number of times.
This uniform wetting of the particles is even more important in apparatuses of the type in question than in the high-shear apparatuses where the intensive mechanical processing facilitates a rapid equalizing of humidity on the particle surfaces.
With a view of obtaining a controlled movement of the particulate material and also a high drying capacity apparatuses resembling the one forming basis for the present invention have been provided with means for keeping the particulate material in fluidized condition.
An example of such an apparatus is disclosed in DE 37 05 343 C2. In said patent specification fluidizing gas is introduced through a number of slots in a rotating member in the bottom of the apparatus and also through the walls in the upper part thereof. The gas introduced through the walls form an angle to the radial direction, thereby increasing the velocity of the vortex-like movement in the chamber of the particulate material being treated.
However, for certain applications a fluidization of the material being treated is inappropriate in view of the result desired. Especially in powder layering processes the fluidizing gas blows off the finest particles and the contact between fine particles and cores, unto which the fine particles shall adhere, becomes insufficient.
It is, therefore, an object of the present invention to provide an apparatus of the discussed type, in which a controlled and uniform movement of the particulate material is obtained without fluidizing said material to any substantial extent. By avoi
Aeromatic-Fielder AG
Page Thurman K.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tran S.
LandOfFree
Apparatus and a method for treating particulate materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and a method for treating particulate materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and a method for treating particulate materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2515246