Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS2648609 A
Publication typeGrant
Publication dateAug 11, 1953
Filing dateJan 21, 1949
Priority dateJan 21, 1949
Publication numberUS 2648609 A, US 2648609A, US-A-2648609, US2648609 A, US2648609A
InventorsDale E Wurster
Original AssigneeWisconsin Alumni Res Found
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of applying coatings to edible tablets or the like
US 2648609 A
Previous page
Next page
Description  (OCR text may contain errors)


Patented Aug. 11, 1953 METHOD OF APPLYING COATINGS TO EDIBLE TABLETS OR THE LIKE Dale E. Wurster, Madison, Wis., assignor to Wisconsin Alumni Research Foundation, Madison, W1s., a corporation of Wisconsin Application January 21, 1949, Serial No. 71,997

6 Claims. 1

My invention relates, generally, to methods of and means for applying coatings, and it has particular relation to the coating of medicinal tablets, chewing gum, candy, nuts, etc.

Among the objects of my invention are: T support the tablets in air in a coating chamber and to coat the same While they are so positioned; to support the tablets in an upwardly flowing air stream; to heat the air prior to its contact with the tablets to dr the coating thereon; to cause the air to flow in a turbulent fashion and tumble the tablets so that they may be coated uniformly; to move the tablets downwardly on a bias transversely of the air stream while they are being coated; to introduce the coating material into the air stream under neath its initial contact point with the tablets; to introduce individually into the air stream different coating materials; and to direct a current of air upwardly in the coating chamber along its inner surface to prevent the coating material from impinging thereon.

Other objects of my invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawing and it comprises the features of construction, combination of elements, arrangement of parts and method steps which will be set forth in detail hereinafter and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference can be had to the following detailed description, taken together with the accompanying drawing, in which:

Figure l is a longitudinal sectional view of a coating mechanism constructed in accordance with my invention;

Figure 2 is a View partly in section and partly in elevation at an enlarged scale showing in more detail the construction of the manifold which directs air upwardly along the inner surface of the coating chamber; and

Figure 3 is a top plan View of the rotating disc which causes the air to flow in a turbulent fashion. 7

Referring now particularly to the drawing, it will be observed that the reference character I'll designates a vertically positioned coatin chamber which may be formed of metal or glass. The coating chamber Ill preferably has a circular cross section, and it may be of conical, modified conical, or cylindrical shape as may be desired. Near its lower end there is provided an entrance I I for the tablets to be coated. An inlet tube [2 communicates with the entrance and slides l3 and 14 are positioned therein to permit the introduction of the tablets to be coated into the chamber Ill in batches.

Within the chamber In there is a screen I which extends transversely thereacross and on a bias so that the tablets to be coated and while they are being coated move across the chamber Ill and downwardly to an exit ['6 with which an outlet tube ll communicates. The tube Il may discharge into a polishing pan or similar receptacle. Slides l8 and It may be provided in the outlet tube I! for. controlling the flow of the coated tablets theretln'ough in batches similar to the manner in which they are permitted to flow onto the screen l5 by the slides l3 and M.

It is desirable that the uncoated and partially coated tablets above the screen l5 be supported in air so that they can be evenly coated. For this purpose air jets 20 and 2| are positioned in the lower end of the chamber Ill below the screen l5 and are directed upwardly to suppl an air stream flowing upwardly in the chamber H) of sufiicient velocity to maintain the uncoated and partially coated tablets slightly out of contact with the screen l5. The air jets 20 and 2| may be connected by conduits 2B and 2| to a suitable. source of compressed air, the pressure of which is adjusted so as to maintain the uncoated and partially coated tablets slightly above the screen l5 to be coated in a manner to be described presently.

Not only is it desirable that the tablets be supported in the air stream which flows uD- wardly through the coating chamber I0 but also it is desirable that they be tumbled so as to coat the same more uniformly. For this purpose the flow of air through the coating chamber II] is arranged so that, in place of it being a streamlined flow, it is a turbulent flow. For this purpose a disc 22 is provided which may be rotated at a constant speed by a motor 23. As shown more clearly in Figure 3 the disc 22 has circular rows 24, 25, 26, and 21 of perforations through which the air from the jets 20 and 2| flows. As shown in Figure l the air jets 20 and 2| register with the circular rows 24, 25, 26, and 21 of perforations so that the air from the former is d rected byv the row of perforations individual thereto. Also as shown in Figure 1 the rows 24 and 21 of the perforations are inclined inwardly while the row 25 ofperforations is inclined outwardly. The remaining row 26 extends Vertically through the disc 22. The several air streams thus directed by the perforations 24, 25, 26, and 2'! impinge on the uncoated and partially coated tablets above the screen IS in a turbulent fashion and cause them to be tumbled so that they can be evenly and completely coated with the coating material.

With a view to drying quickly the coating material on the tablets, provision is made for heating the air as it passes upwardly through the chamber ll) underneath the screen [5. For this purpose an electric heater element 28, in the form of a grid, may be positioned immediately above the rotating disc 22. It will be understood that the heater element 28 maybe connected for energization to a suitable Current source and that the degree of heat can be varied by varying the amount of current fl g.


The material for coating the tablets may be supplied through conduits 30, 3| and 32, the number being determined by the number of different coating materials to be employed. Each of the conduits 30, 3| and 32 terminates in a nozzle 33 which, as shown in Figure 1, is directed against the tablets near the upper edge of the screen l5 so that the coating material is supplied to the tablets as soon as they pass through the entrance II. It will be understood that various coating materials can be supplied. As illustrated in Figure 1, the conduit is arranged to have powdered lactose blown therethrough. The conduit 3| carries an acacia solution, while the conduit 32 may carry a sugar solution. It will be understood that these particular materials are mentioned for illustrative purposes only and that other coating materials can be used as may be desired.

Certain of the coating materials may tend to adhere to the inner surface of the coating chamber Ill particularly in the immediate vicinity of the screen l5. In order to prevent this a ringlike manifold 34 may be positioned just above the screen I5. As shown in Figure 2 the manifold 34 has outwardly and upwardly directed openings or apertures 35 which cause air supplied to the manifold 34 from a suitable source of compressed air to flow in the directions indicated by the arrows 36 over the inner surface of the chamber In for preventing the coating material from engaging the same.

At the upper end of the coating chamber II] a screen 31 may be provided to prevent the escape of tablets in the event that the pressure supplied through the jets 20 and 2| should be sufficiently great as to cause them to rise to this position. An exhaust tube 38 connects the coating chamber II) to a suitable recovery and exhaust chamber as will be understood readily.

In operation, the motor 23 is energized to drive the disc 22 at the desired speed. Air under pressure is supplied through the conduits 20' and 2| to the jets 20 and 2| respectively so that the uncoated and partially coated tablets on the screen I5 will be tumbled thereabove. This air pressure also is adjusted so that when the tablets are fully coated it will be insufficient to maintain them above the screen l5 at the lower end thereof adjacent the exit [6. The current flowing through the heating element 28 is adjusted so that the coating applied to the tablets above the screen I5 is dried satisfactorily. The coating materials supplied to the conduits 30, 3| and 32 are arranged and adjusted so that the desired proportions will be applied to the tablets at rates which will provide the desired thickness of coating. Air is supplied to the manifold 34, it being understood that the pressure at the apertures 35 therein is slightly greater than the air pressure at the air jets 20 and 2| so that the desired air flow takes place along the inner surface of the chamber [0 to prevent the coating material from impinging thereon.

Now, the slide I3 is raised to permit a charge of uncoated tablets to flow downwardly through the inlet tube I2 against the slide Id. The slide I3 is closed and then the slide I4 is opened. The uncoated tablets flow through the entrance II onto the upper end of the screen I5 and are immediately lifted thereabove and tumbled. At

4 the same time they are subjected to the atomized flow of coating materials from the nozzles 33 which are supplied individually by the conduits 30, 3| and 32 in the manner described. The partially coated tablets move transversely of the chamber .IO and downwardly on a bias but are still being tumbled above the screen l5 until the coating thereon is sufficiently heavy so that the upwardly flowing air stream is insufficient to maintain them out of contact with the screen '|5. When all of the tablets have been completely coated, the slide I8 is opened and they are allowed to dischargethrough the exit l6 into the outlet tube II. Thereafter the slide 18 is closed and the slide I9 is opened to permit the coated tablets to be discharged into the polishing pan or other receptacle as may be desired.

It will be obvious that certain changes can be made in the foregoing construction and method without departing from the spirit and scope of this invention. Accordingly, it is intended that all matter shown in the accompanying drawing and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. The process of covering eatable tablets of the type of medicinal tablets, chewing gum, candy and nuts with a sugary coating which comprises: moving an air stream in a confined space upwardly past the eatable tablets with a force sufiicient to suspend them continuously therein, and introducing the sugary coating material into said air stream prior to its contact with the eatable tablets.

2. The invention, as set forth in claim 1, wherein the coating is wet on application and the air stream is heated to dry quickly the coating applied to the tablets.

3. The invention, as set forth in claim 2, wherein the air stream is turbulent to tumble the tablets whereby they receive a coating of uniform thickness.

4. The invention, as set forth in claim 1, wherein the tablets move downwardly on a bias transversely of the air stream while being coated.

5. The invention, as set forth in claim 4, wherein the coating material is introduced into the air stream at a position close to the initial contact point thereof with the tablets.

6. The invention, as set forth in claim 1, wherein the coating material comprises a plurality of different materials and they are introduced separately into the air stream.


References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,473,165 Steigmeyer Nov. 6, 1923 1,546,922 Faber July 21, 1925 1,725,608 Zebulski Aug. 20, 1929 2,059,983 Dent et al. Nov. 3, 1936 2,259,879 Denning -1 Oct. 21, 1941 2,339,932 Kuhl Jan. 25, 1944 2,349,230 Thomas May 16, 1944 2,399,717 Arveson May 7, 1946 2,447,006 Gamson Aug. 17, 1948 2,459,836 Murphee Jan. 25, 1949 2,491,632 Wieder Dec. 20, 1949 2,493,198 Kelley, Jr. Jan. 3, 1950 2,498,405 Fader Feb. 21, .1950 2,536,168 Goggin Jan. 2, 1951 2,561,392

Marshall July 24, 1951

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1473165 *Dec 4, 1922Nov 6, 1923Steigmeyer FrederickSeed-conditioning apparatus
US1546922 *Feb 24, 1920Jul 21, 1925Atomized Products CorporaProcess oe desiccation
US1725608 *May 1, 1928Aug 20, 1929 Process and apparatus for coating granular material
US2059983 *Jun 27, 1932Nov 3, 1936Gen Plastics IncMethod of coating abrasive particles
US2259879 *Oct 25, 1937Oct 21, 1941F E Schundler & Co IncLightweight mineral material
US2339932 *Apr 10, 1941Jan 25, 1944Standard Oil Dev CoChemical process
US2349230 *Apr 13, 1942May 16, 1944Shell DevApparatus for the preparation of catalysts
US2399717 *Nov 1, 1941May 7, 1946Standard Oil CoProduction of dust coated materials
US2447006 *Feb 23, 1946Aug 17, 1948Great Lakes Carbon CorpProduction of sulfo compositions
US2459836 *Dec 11, 1942Jan 25, 1949Standard Oil Dev CoControlling reaction temperatures
US2491632 *Sep 9, 1944Dec 20, 1949Stauffer Chemical CoMethods of producing insecticidal compositions containing relatively small quantities of 2,2-bis(p-chlorophenyl) - 1,1,1 - trichlorethane
US2493198 *Jan 7, 1947Jan 3, 1950North American Cement CorpProcess for producing lightweight aggregates
US2498405 *Mar 11, 1946Feb 21, 1950Jeffrey Mfg CoContinuous vibrating reaction chamber
US2536168 *Sep 29, 1947Jan 2, 1951Clark & Clark CoAmphetamine chewing gum
US2561392 *Aug 11, 1945Jul 24, 1951Donald E MarshallProcess and apparatus for treating solutions to recover and coat solid particles
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2799241 *Feb 6, 1953Jul 16, 1957Wisconsin Alumni Res FoundMeans for applying coatings to tablets or the like
US2833241 *Apr 18, 1955May 6, 1958Crowley George CMachine for coating spherical objects
US2844489 *Dec 20, 1957Jul 22, 1958Knapsack AgFluidized bed coating process
US3012900 *Apr 26, 1957Dec 12, 1961Phillips Petroleum CoDusting particles of adhesive materials
US3089824 *Apr 30, 1959May 14, 1963Wisconsin Alumui Res FoundatioGranulating and coating process for uniform granules
US3097958 *Jun 10, 1958Jul 16, 1963Chain Belt CoFluidized coating machine
US3112220 *Feb 26, 1960Nov 26, 1963Abbott LabMethod and apparatus for coating particles
US3145146 *Oct 31, 1961Aug 18, 1964Warner Lambert PharmaceuticalModified mannitol for pharmaceutical tablets
US3152005 *Mar 29, 1962Oct 6, 1964Dow Chemical CoProcess for the preparation of pelletized solids
US3253944 *Jan 13, 1964May 31, 1966Wisconsin Alumni Res FoundParticle coating process
US3256111 *Dec 4, 1964Jun 14, 1966Abbott LabMethod for coating tablets
US3328256 *May 27, 1963Jun 27, 1967Gaunt William ESpherical beads and their production
US3361631 *Sep 30, 1963Jan 2, 1968Sandoz AgMethod of sugar coating pharmaceutical tablets
US3464926 *Apr 26, 1965Sep 2, 1969Pennwalt CorpProcess for encapsulation
US3635752 *Nov 4, 1969Jan 18, 1972Monsanto CoProcess for the preparation of glass-concentrate capsules in a polyvinyl chloride matrix
US3800740 *Dec 14, 1972Apr 2, 1974Int Nickel CoApparatus for decomposition of metal carbonyls
US3849077 *Aug 28, 1972Nov 19, 1974Rhone ProgilContinuous method for the recovery by condensation in the solid state of sublimable substances
US4100148 *May 4, 1976Jul 11, 1978Rutgerswerke AktiengesellschaftStorage-stable, very quickly hardenable, one-component sealant based on mercapto-terminated polymers
US4338878 *Nov 26, 1980Jul 13, 1982United Technologies CorporationFluidized bed with sloped aperture plate
US4615698 *Mar 23, 1984Oct 7, 1986Alza CorporationTotal agent osmotic delivery system
US4675140 *May 6, 1985Jun 23, 1987Washington University Technology AssociatesSupplying suspension to rotating surface
US4735015 *Nov 25, 1983Apr 5, 1988Basf CorporationPolyoxyethylene-polyoxybutylene block copolymer
US4772477 *Oct 17, 1986Sep 20, 1988Balchem CorporationMeat acidulant
US4803092 *Apr 28, 1988Feb 7, 1989Balchem CorporationMethod of acidulating a comminuted meat product
US5095035 *Dec 24, 1990Mar 10, 1992Eby Iii George ASweet carrier
US5098893 *Feb 12, 1990Mar 24, 1992Pafra LimitedStorage of materials
US5190775 *May 29, 1991Mar 2, 1993Balchem CorporationEncapsulated bioactive substances
US5211896 *Jun 7, 1991May 18, 1993General Motors CorporationComposite iron material
US5254168 *Jun 4, 1992Oct 19, 1993Howard LittmanDual-jet and spray; automatic monitoring
US5350659 *Mar 31, 1993Sep 27, 1994Xerox CorporationPreparation of conductive toners using fluidized bed processing equipment
US5591373 *Feb 15, 1996Jan 7, 1997General Motors CorporationEncapsulated in polymer shell of polyetherimide, polyethersulfone or polyamideimide
US5628945 *Aug 3, 1992May 13, 1997Riman; Richard E.Controlling chemical distribution of substances, e.g., by dry mixing particles of powder and triggerable granule facilitator to form microcapsules, dry mixing to form granules, ceasing mixing while keeping granules in dry phase
US6013286 *Dec 8, 1992Jan 11, 2000Balchem CorporationEncapsulated bioactive substances
US6209479Dec 30, 1998Apr 3, 2001Aeromatic-Fielder AgApparatus for coating tablets
US6224939 *May 10, 1999May 1, 2001Fuisz International Ltd.Ejecting a solid matrix additive upwardly through a nozzle, additive descends into a free-fall condition, and is then encapsulated below its ejection point, solidification occurs while still in free-fall; taste masking
US6280683Oct 22, 1999Aug 28, 2001Hoeganaes CorporationMetallurgical compositions containing binding agent/lubricant and process for preparing same
US6296842Aug 10, 2000Oct 2, 2001Alkermes Controlled Therapeutics, Inc.Forming mixture comprising biologically active agent, a biocompatible polymer, and polymer solvent; removing polymer solvent thereby forming solid polymer/active agent matrix; annealing exterior surface of matrix
US6312521Dec 14, 1999Nov 6, 2001Primera Foods CorporationApparatus and process for coating particles
US6368658Apr 17, 2000Apr 9, 2002Scimed Life Systems, Inc.Coating medical devices using air suspension
US6426210May 24, 1999Jul 30, 2002Inhale Therapeutic Systems, Inc.Storage of materials
US6479065Mar 7, 2001Nov 12, 2002Alkermes Controlled Therapeutics, Inc.Process for the preparation of polymer-based sustained release compositions
US6589560Jun 11, 2001Jul 8, 2003Nektar TherapeuticsStable glassy state powder formulations
US6602315Jul 20, 2001Aug 5, 2003Hoeganaes CorporationMetallurgical compositions containing binding agent/lubricant and process for preparing same
US6685775Feb 19, 2002Feb 3, 2004Vector CorporationWurster air diverter
US6730349Mar 1, 2002May 4, 2004Scimed Life Systems, Inc.For coating medical implants that are agitated or moved due to the vibration of vibrating structure
US6825031Feb 8, 2002Nov 30, 2004Nektar TherapeuticsSpraying into a hot gas stream an aqueous mixture of the material and a carrier substance which is water-soluble or water-swellable, thereby drying the mixture to particles which contain the material and the carrier substance
US6881482Aug 16, 2002Apr 19, 2005Southwest Research InstituteExposure to appropriate electromagnetic energy selectively to heat core material with higher dielectric constant and dissipation factor, directly or indirectly fusing shell material and forming microcapsules or hardening to polymerize
US6900162Mar 26, 2003May 31, 2005Georgia-Pacific Resins, Inc.A coated aggregate material for enhancing the extended delivery of nitrogen needed for plant development and growth, the coated aggregate material having a slow release (extended-release) nitrogen coating of a particulate UF
US6919373Feb 19, 1999Jul 19, 2005Alza CorporationMethods and devices for providing prolonged drug therapy
US6930129Mar 8, 2001Aug 16, 2005Alza CorporationOrally administering a dosage form containing a central nervous system-acting drug in a pharmaceutically acceptable carrier, wherein said dosage release the drug at an ascending release rate for an extended time period
US6936573Mar 26, 2003Aug 30, 2005Georgia-Pacific Resins, Inc.Treating the seedling with urea-formaldehyde polymer particles, use as fertilizer for enhancing nitrification
US6936681Mar 26, 2003Aug 30, 2005Georgia Pacific Resins, Inc.Slow release nitrogen fertilizer
US7140874Aug 6, 2002Nov 28, 2006Southwest Research InstituteMethod and apparatus for testing catalytic converter durability
US7213367Mar 26, 2003May 8, 2007Georgia-Pacific Resins, Inc.Slow release nitrogen seed coat
US7407551Nov 4, 2003Aug 5, 2008Boston Scientific Scimed, Inc.Mechanical and acoustical suspension coating of medical implants
US7429407Sep 16, 2003Sep 30, 2008Aeromatic Fielder AgUsing pneumatic means to guide and control movement; eliminating partitions; uniform, rapid spraying; high capacity; reducing mechnical stress
US7625201Sep 6, 2006Dec 1, 2009Southwest Research InstituteMethod and apparatus for testing catalytic converter durability
US7687092Aug 1, 2003Mar 30, 2010Purac Biochem B.V.Encapsulated crystalline lactic acid
US7730603 *Apr 18, 2007Jun 8, 2010Gm Global Technology Operations, Inc.Methods for forming a magnet in a rotor
US7744925May 20, 2005Jun 29, 2010Quadrant Drug Delivery LimitedInsulin and a sugar alcohol; powder for pulmonary delivery; inhalants; storage stability
US7780991May 20, 2005Aug 24, 2010Quadrant Drug Delivery Limitedfor ballistic administration of a bioactive material to subcutaneous and intradermal tissue, delivery vehicle being sized and shaped for penetrating the epidermis; vehicle further comprises a stabilizing polyol glass, in particular, trehalose
US7785631May 20, 2005Aug 31, 2010Quadrant Drug Delivery LimitedSolid dose delivery vehicle and methods of making same
US7966745 *May 19, 2004Jun 28, 2011Urea Casale S.A.Fluid bed granulation process and apparatus
US8163798Aug 12, 2003Apr 24, 2012Alza CorporationAdministering methylphenidate at an ascending release rate over an extended time period; therapeutic affect over long time period; hyperactivity/attention deficit disorder
US8541028Aug 3, 2005Sep 24, 2013Evonik CorporationMethods for manufacturing delivery devices and devices thereof
US8613131Apr 20, 2010Dec 24, 2013GM Global Technology Operations LLCMethods for forming a magnet in a rotor
US8629179Oct 19, 2009Jan 14, 2014Alza CorporationMethods and devices for providing prolonged drug therapy
US8728528Dec 18, 2008May 20, 2014Evonik CorporationProcess for preparing microparticles having a low residual solvent volume
USRE37872 *Mar 17, 1999Oct 8, 2002Inhale Therapeutics Systems, Inc.Enzymes
USRE38385 *Aug 28, 2001Jan 13, 2004Nektar TherapeuticsProteins, peptides, nucleosides, nucleotides; carrier carbohydrates and and sugars which are water soluble or water swellable and in a glassy amorphous state; storage stability
USRE39497 *Aug 28, 2001Feb 27, 2007Nektar TherapeuticsStorage of materials
DE1182394B *Oct 26, 1962Nov 26, 1964Foremost Dairies IncVerfahren zum Dragieren pharmazeutischer Tabletten
EP1649937A1 *Apr 18, 2000Apr 26, 2006Boston Scientific LimitedCoating medical device using air suspension
WO2000062830A2 *Apr 18, 2000Oct 26, 2000Scimed Life Systems IncCoating medical devices using air suspension
WO2010085780A1Jan 26, 2010Jul 29, 2010Teva Pharmaceutical Industries Ltd.Processes for coating a carrier with microparticles
U.S. Classification427/213, 424/440, 424/439, 159/DIG.300, 428/27, 426/302
International ClassificationA61J3/00, A61K9/28
Cooperative ClassificationA61K9/28, A61J3/005, Y10S159/03
European ClassificationA61K9/28, A61J3/00C