US2379817A - Process and apparatus for making capsules - Google Patents

Description

July 3, 1945. q. BB 2,379,817

' PROCESS AND APPARATUS FOR MAKING A CAPSULE Filed Oct. 30, 1940 S'ShGGtS-ShGSi l C'crr/ ,5 Q6196 a TTowx' 7 July 3, 1945. c. E. MABBS' PROCESS AND APPARATUS FOR MAKING A CAPSULE Filed Oct. 50, 1940 s Sheets-Sheet 2 l e Ql a s July3, 1945. c MABBS PROCESS AND APPARATUS FOR MAKING A CAPSULE 3 Sheets-Sheet 3 Filed on. so, 1940 NVELNTOQQ Cam/-57 69770665 '7 PM, M,

Patented July 3, 1945 OFFICE rnocnss srrnna'rns FOB EAPSULES Application October so, 1940, semi No. scans 24 Claims.

This invention relates to the capsulation of liquid or plastic core materials in a shell of congealable material. Gelatin is commonly used to 7 form capsule shells. Because of its aihnity for water and because it becomes insoluble or prefor ingredients to be capsulated,' capsulation heretofore has been limited to oils and oil solvents. v

The primary object is to capsulate aqueous or other core materials which, when in contact with gelatin or other available shell material, will change the physical or chemical condition or properties of the shell material and render the capsule useless.

A more detailed object is to provide a capsule comprising a core, an outer shell of gelatin or the like and a partition or inner shell permanently separating the core material from the outer shell.

above character having a separating or partition film which is substantially solid at ordinary temperatures but capable of liberating the core ma:

' terial at body temperature.

description taken in connection with the accompanying drawings. in which Figure l is a schematic view of an apparatus for practicing the novel method.

Fig: 2 is a fragmentary perspective view of a portion of the retrieving mechanism.

Fig. 3 is a diametrical cross-sectional view of the drop formin nozzle.

Figs. 4 to 9 illustrate successive stages in the Q formation of a capsule.

Fig; it is a cross-sectional view of-a completed capsule havlngasingle core.

Fig. 11 is a similar view ofa multl-cell capsule. Fig. .12 is a view similar to Fig. ashowing a final stage in the-formation of the. multi-cell capsule. 7

While the invention is susceptible of various modifications and alternative constructions, I,

have shown in the drawings and will herein de-' A fur her ject is to provide a. capsule of the methods of carrying out the invention. It is to he understood that I do not intend to limit the invention by such disclosure. but aim to cover all modifications, alternative constructions, methods a and uses falling within the spirit and scope of cipitated when exposed to certain other carriers the invention as expressed in the appended claims. As shown in Figs. 10 and 11 capsules designated generally at 9 and constituting the present invention are generally spheroidal in shape and comlo prise one or more cores W in the form of a generally spherical globule composed of or containing the material to be capsulated completely encased in a. seamless and thin substantially solid ll of substantially uniform thickness conl5 stituting a partition or lining for maintaining 2; case of the multi-cell capsules (Fig. 11) each core is enclosed by partition H which separate the cores from each other in a, single .globule of shell material.

Ordinarily the core consists'of the medicinal as or other material to be capsulated, dissolved or V dispersed in water, glycerin or other liquid, which reacts with the shell material.

The partition layer ll must possess well-defined properties. First, it must be immiscible in 30 or unaffected by the materials, either of the core to stable at body temperatures, so as to free the core materials. Preferably, the lining material should not shrink or crack on standing after coni sealing. Finally, where, as in the present instance, the capsule is produced by natural drop 40 formation, the lining should have a relatively sharp melting point, that is, be capable of soliditying rapidly and completely on cooling below its melting point. Vegetable and animal oils, greases, and certain waxes or various mixtures of as these may be used. Parafiln having a. melting point slightly. above body temperature has proved very satisfactory for use with aqueous core ma, terials. 4

To produce the capsules by natural drop forma- Hll ticn, measured quantities of the core, lining, and

shell materials are subjected to the natural forces of gravity, capillarity, and surface tension while the materials are maintained in" the proper positional relation and at the correct temperatures.

scribe in detail the preferred embodiments and to To this end. globulesofthe liquid core material are discharged intermittently from the end of an orifice 13 which preferably is circular. The lining and shell materials in the liquid state are discharged in properly timed relation from successively larger annular orifices l4 and I5 surroundfing the core orifice and, for purposes to appear later, preferably spaced progressively increasing distances below the core orifice. The three ori fices face downwardly and are positioned sothat the composite drop, as it forms below and-hangs downwardly from the orifice l5 in the final stage,

' contacts a column I6 of cooled receiving liquid,

the density of which is correlated with that of thecomposite drop.

In the apparatus illustrated, the;three orifices are positioned at the lower end of a nozzle l1 defined by the lower ends of tapering relatively thin walled tubes I8, I9, 20. Herein, the upper .endof the tube I8 is threaded into a metal sleeve 2| threading into a metal tube 39 by which it is held in abutment with a block 25 of insulating material. The tube 18 is formed short of the orifice 13 with shoulders 2| against which abuts the end of a tube 2| threading at its upper end into the centralbore 25" of the block 25 and having a bore 2| through which the cold core liquid 22 fiows to the orifice I3. The tubeZI is composed of insulating material and preferably is separated from-the tube l8 bieafdead air space 2| which further insures insulation of the core liquid from the heated lining and shell liquids 23 and 24 to a point adjacent the orifice IS. A screw 25 .threaded into the upper end of the block 25".

has a bore 26. communicating through openings 21Iwith afitting 28 at'the end of a conduit 29 through which the core liquid .is forced by a metering pump 30. On the quick upstroke of the pump piston 3| producedl byya spring 32, core liquid from a storage tank "32 -3 is drawn into the pump cylinder 33 through acheck valve 34. On

the down stroke the valve 34 is closed and a metered amount of the-liquid is discharged .through a check valve ;3 5 into the conduit 29L By immersing the tank an in a water bath 36' .coolcd bla coi1-3I,-the core liquid is maintained .at the desired temperature, .'preferably about 35 degrees Fahrenheit below the meltin point of the lining materiel.

The tube I9 is threaded intoa portion of the sleeve 2| spaced below the tube I8 and cooperates with the latter to define a passage 40 for flow t of the lining material to the orifice l4.

upper end of this passage communicates with a supply conduit 42 through a fitting "threading into a side bore in the sleeve 2| and an opening in the tube 39. Through a valve 44, lining material 23 is drawn from a tank. 45-by a pump 46 'whose discharge is timed accurately withthat of heated to approximately 150 degrees Fahrenheit in 'atank 48 is discharged intermittently by a cam driven pump1-49 through'a simflar control valve 50 into a. conduit 5| and a fitting 52. The

latter communicates with a downwardly; tapering annular ,chamber 53 around the tube l9 and 'within a tube i9 threaded into a counter bore in the sleeve "2| and tapering to an orifice I9. At its lower end, the tube I9 is flared outwardly to form' a flange l9 which fits against the inner downw r ly o v rsin wall of. the tube I9.

Fahrenheit, when paraffin is Holes l9 in the flange permit the flow of the shell liquid to the orifice l5 with a slight Venturi efiect which contributes to the proper positioning of the lining material and the formation of lining and gelatin layers of uniform thickness throughout.

To assist in holding the excess material in the nozzle passages following falling of a drop and also to increase the efiective area of the tip from which the drop falls, the tubes I9 and 20 are spaced apart to form a capillary ring 20 around tric heater 54 not only to facilitate initiating and maintaining proper operation of the apparatus .but also to effect final heating of the lining and shell liquids so as to insure an accurately controllable final temperature at the nozzle orifices.

The heat is conducted through the sleeves 39 and 2| and the metal tubes l8, I9, 20 and IS. the present instance, the capacityof the heater is such that the lining and shell materials are discharged from their orifices at about 160 degrees Fahrenheit. v e The relative sizesfand spacing of the nozzle orifices are approximately as shown in the drawings. This relation and the dimensions of the individual orifices will, of course, vary with the materials used, the size of capsule to be produced, the character of the receiving liquid, etc.

The pumps 30, 46 and-49 are of the same construction, each having a piston 3| raised by. a

.spring 32 and projected downwardly with an ac celerated motion by acam 55 acting on a follower 56. The cam is. shaped to terminate the active stroke abruptly and permit the return movement of the piston to be initiated quickly. As a result of this, the pump pressure is released quickly and the liquids in the nozzle passages are permitted to take' their natural positions. This, combined with the tapering of the passages 40, and 53 and the narrowness of the annular orifices l4 and I5 and the capillary ring 20 avoids dribble and causes the small amounts of surplus materials 'left at the orifices following breaking off of the the, core, lining and shell materialsare of'dif-- ferent lengths and start successively as shown by the time;chart of Fig. 4. Preferably, the discharge of lining material overlaps both ends of the core discharge while the discharge of shell material is initiated substantially before the lining and continues for a-bri'ef time after the lining and core materials have been cut off. lit has been found that this timing is obtainable by making the cams 55 of substantially the same lengths as shown and by properly positioning them-angu- I larly on the shaft 58. The variations in the de- For example, a gelatin solution of. the solids-concentration used'is highly viscous and reacts slowly to pressure changes; consequently,

asvaaiv the pressure must be applied an appreciable length of time before emission of the solution beins. Also, the flow will continue for some time after the pump stroke has been completed. For the same reasons, the characteristics of the lining material determine the timing of the active stroke of the pump it.

In the final stage of formation of the composite drop and while the drop is hanging on the lower end of the nozzle tip, it contacts and is partially supported bythe receiving column iii. This is a liquid, such as vegetable or mineral oil,

or a mixture thereof,'which is free flowing at temperatures below the gel or melting points of the shell and lining materials, and has a density, for example 0.80, somewhat less than that of the compound drop so that each drop descends slowly and yet does not interfere with the formation of the succeeding drop. The descent is prolonged suficiently to enable the lining ii to solidify completely and the shell ii to cool below its ge point and thereby congeal to a rubbery consistency. The receiving liquid should possess some dehydrating property and its interracial surface relation to that of the gelatin solution is such as to accelerate the action of capillarity in caus ing the drop to take a generally spheroidal shape on leaving the nozzle.

. The receiving column is defined by a tube 60 disposed within a larger tubeGi to the lower end of which the circulating receiving liquid is delivered by a motor driven pump 62 through a coil 63 immersed in a cooling tank 64 by which the liquid is maintained at the desired temperature, usually about 40 degrees Fahrenheit. The liquid flows upwardly between the tubes 60 and and then downwardly through the tube 60 so that the drop initially contacts the coolest portion of the column. The lower end of the tube 60 is disposed within a'tank 65 connected intermediate itsends to the inlet of the pump 62.

Provision is made for raising and lowering the 7 level of the receiving liquid and adjustment ofthe spacing of the receiving liquid relative to the nozzle. This'is accomplished herein by an auxiliar reservoir communicating with the tank 85 and mounted for vertical movement as by turning a hand wheel 16. i l

The capsules descending through. the liquid column ii are delivered to a suitable retrieving mechanism. As shown, this comprises an inclined chain type conveyor 6.6 supported by pulleys 61 and 68 and sprockets 69 and "so that the upper run of the chain, which travels along fiat guides 14, ispositioned to receive the completed capsules and carry them out of the receiving liqmit the excess oil to' drain oil. The rod also wipes alongthe underside of the chain and by .capillary action removes any surplus oil from shown in Figs. 5 to 9. .After the falling of one drop and during the return strokes of the pump plunger, the materials will be held in the nozzle passages as shown-in Fig. 5, the shell ma eri and surface tension.

being drawn upwardly into the nomle :as shown by capillary action due to the ring 2%.

,As shown in Fig. 4, the flows of shell, lining and core materials are initiated successively. When the pump pistons have advanced to a, the liquids will occupy approximately the positions shown in Fig. 6. As the'flows progress, the composite globule hanging from the nozzle enlarges as shown in Fig. 7 which is about the time the liquid pump completes its active stroke, as indicated at b. By this time, the core globule hangs by a narrow contracted neck it which soonbecomes pinched ofl whereupon the coreglobule assumes a spherical shape Within the bodies of lining and shell materials still hanging from the orifices i9 and it. As shown in Fig. 8, the lining material breaks off at the completion of the active stroke of the pump 96, which occurs at c, a characteristic curl 19 being formed at the time. Not until this stage does the downwardly hanging globule contact the receiving liquid and become supported thereby as shown in Fig. 8. A rather delicate balance is established between the gravity of the receiving liquid, the weight of the drop and the spacing of the receiving liquid below the nozzle. It is such that if the flow of shell material were interrupted simultaneously with that of the lining material, the globule, would remain suspended as shown in Fig. 8. Thus, when the globule encounters the receiving liquid, its motion is interrupted momentarily for a purpose to appear later. By continuing the flow of shell material as indicated at d, sufilcient weight is added to cause the drop to overcome the buoyant force exerted by the receiving liquid and break from the 0rii'lce'20 as shown in Fig. 9 whereupon the drop as a whole contracts into a sphere'due to the interfacial action of capillarity Momentary suspension of the globule by the receiving liquid in the final stage is an important factor in proper formation of the present type of capsule. This is because the relatively cold core material in leaving its orifice l3 causes the immediately adjacent lining material to congeal' and thereby attach itself to the tip of the tube l8. If the downward movement of the composite drop were permitted to continue uninterruptedly, the congealed lining material thus attached to the core orifice tip would be torn away and broken permitting contact of the core and shell materials. However, by supporting the globule in the receiving liquid suflicient time is allowed for the lining material to become detached, the shellmaterial acting as a receiving liquid for the globule of core and lining material which there- 'by takes'the desired spherical form with the linimportant. If'this'spacing is too great, fracture of the lining material at the orifice i3 is apt to occur. If it is too small, the buoyant force of the receiving liquid will not-permit, of complete separation of the core material Irom the orifice [3 before the complete drop breaks rom the orifice l5.

i The danger of the lining material congealing and adhering too firmly on the core orifice is eliminated in the present instance by providing the heated shield is around the advancing column of core liquid, which shield defines the core orifice l3. This body of heated metal indicated at I8 serves the dual purpose of keeping the lining material fully liquid clear to its area of contact with the core and of transmitting suflicient heat to the orifice 13 to remelt any of the lining material that may become congealed therein by the passage of the colder core material there'- through. This remelting occurs at the time when the shell liquid first encounters the receiving liquid and causes the interruption in the drop movement during which the lining material be- ,comes released as above described from the core and shell materials are at all times maintained properly separated by the lining inaterial which congeals rapidly owing to its sharp melting point and becomes completely solid before the drop has descended far into the column l6. During the descent of the composite drop, the gelatin congeals gradually and by the time it reaches the retrieving mechanism, it will have set surficiently to be handled without danger of changing the shape of the drop.

The size of the finished capsule is, of course, determined by the quantity of core material to be capsulated and thi in turn determines the amount of the lining and shell materials required.

These quantities and the physical properties of the various materials forming the drop will determine the size of the orifices underthe established drop weight and liquid column stability laws.

To form the multi-cell capsules shown in Figs. 11 and 12, the same general arrangement of nozzle orifices above described is employed. In addition, the nozzles are multiplied according to the number of cells to be formed in each capsule and disposed adjacent eacnother as sho'wnin Fig. 12 so that the globules of shell liquid discharged from the orifices l-5 will'contact each .other about the time that the two composite globules encounter the receiving liquid as shown. As" a result, all of the globules break from the res ective nozzle approximately simultaneously whereupon the natural forces act to shape the several globules into a composite ovate drop in which the lining and core drops remain separated in the combined globule of shell material.

I claim as my invention: I

1. Capsulating apparatus having, in combination, a projection defining a downwardly facing orifice, means for discharging measured quantities of a liquid to be capsulated from said orifice,

to form a drop, an annular orifice surrounding said first mentioned orifice, a third orifice surrounding said annular orifice, and mechanism for discharging congealable lining and shell materials from said annular and third orifices to enclose said drops and cause the formation of a compound drop by drop formation and having the core and shell separated by said lining material.

orifice, means for discharging measured quantito form a drop, an annular orifice surrounding said first mentioned orifice,'mechanism .for discharging liquid solidifiable material from said annular orifice to enclose each drop of said liquid,

a third orifice surrounding said annular orifice, mechanism for discharging liquid solidifiable shell first orifice and axially spaced therebelow, means providing a third larger orifice urrounding said second orifice and axially spaced therebelow, a

column of liquid disposed immediately below' said orifices to contact the materials discharged therefrom, mechanism for discharging from said second and third orifices quantities of immiscible liquids congealable at the temperature of said column, and mechanism for discharging from said first orifice a quantity of a core material which is immiscible in the liquid discharged through said second orifice, said mechanism being timed to cause the formation of a compound drop by drop formation in which the core and shell materials are separated by the material discharged from said second orifice. v

4. Capsulating apparatus comprising means defining a downwardly facing orifice, means providing a second larger orifice surrounding said first orifice, means providing a third larger orifice surrounding said second, orifice, a, column of liquid disposed immediately below said orifices to contact the materials discharged therefrom, mechanism for efiecting timed discharges from said second and third orifices of quantities of immiscible liquids congealable at the temperature of said column, and mechanism for,timing the discharge from said first orifice'of a quantity of a core material which is immiscible in the liquid discharged through said second orifice.

5. Capsulating apparatus comprising three subliquid core material, a second orifice surrounding the first orifice and communicating with a supply of molten lining material, a third orifice surrounding said second orifice and communicating with a supply of gelatin, mechanism operable intermittently to discharge measured quantities of said materials from their respectivev orifices to form composite drops by drop formation each having the core and shell separated by said lining material. l

'7. Capsulating apparatus having,"in combination, first, second and third orifices respectively arranged one within the other, means for discharging shell, lining and corematerials from the respective orifices to form a compound drop, said orifices being arranged to cause the core,

ties of a liquid to be capsulated from said orifice steps of intermittently discharging a globule of said first liquid from a downwardly facing orifice, correlatively discharging aquantity of said third liquid from a lower surrounding orifice, and correlatively discharging a quantity oi said second liquid from an orifice surrounding said second orifice and spaced therebelow, the amounts of said second and third liquids being such as to cause the compound drop to fall from said third orifice by drop formation.

9. The process of capsulation which includes successively initiating the flow of shell, lining and core'materials from concentric orifices of progressively decreasing sizes to form a compound drop globule, successively terminating the flow of the core, lining, and shell materials respectively, and

supporting the globule in a cooled receiving liquid after termination of the core material dis-' charge.

10. The process of capsulation which includes successively initiating the fiow of shell, lining and core materials from concentric orifices of progressively decreasing sizes to form a compound drop,

the lining material being immiscible with both the core and shell materials, and supporting the globule of said materials in a cooled receiving liquid during the final stage of drop formation! 11. The process of capsulation which includes successively initiating the fiow of shell, lining and core materials from concentric orifices to form a compound drop globule, successively terminating the fiow of the core and shell materials respectively, so that the discharges of the core,

lining and shell materials are of diiferent lengths,

and supporting the globule ina cooled receiving liquid during the final discharge of the shell material. f

12. The method of forming compound drops of first and second reactable liquids and a third liquid immiscible therewith, which includes the steps of intermittently discharging a globule 01 said first liquid from a downwardly facing orifice, simultaneously discharging a quantity of said third liquid from a surrounding orifice, and simultaneously discharging a quantity of said second liquid from an orifice surrounding said second orifice.

13. In capsulating apparatus, the combination of a pair-of concentric spaced tubes defining a passage there-between for the flow of a melted congealable shell material therethrough, a flange on one of said tubes closing saidpassage and having annularly spaced holes through which the shell material is extruded, the central one of said tubes defining a passage for the flow of within the extruded shell material. 14. The method of forming compound drops a material of first and second reactable liquids and a third,

liquid immiscible therewith, which includes the steps of intermittently vdischarging quantities 01' said first, third, and second liquids from concentric orifices oi successively increasing size.

.15. The process of capsulation which includes the steps of intermittently dropping globules of liquid core material from an orifice, discharging an immiscible congealable liquid around each drop to enclose the latter, and correlatively discharging a congealable liquid around said second liquid to e'nclose'the latter correlatively spaced apart .relation,

liquids into a composite drop -'with the first and second liquids separated by the third liquid, and partially supporting said drop during its formation and descent in a liquid of a density less than that of the drop. 17. The process of capsulation which includes the step of subjecting quantities of first and second miscible liquids and a third liquid cible with the first and second liquids to natural forces of gravity capillarity and surface tension to com blue the same into a composite drop ha'said first liquid enclosed by said third liquid and the third liquid enclosed by the second liquid.

18. The process of capsulation whichlncludes the steps of correlatively discharging separated quantities of core liquid and heated shell liquid from orifices disposed one within the other. and correlatively discharging a measured quantity of a congealable liquid from an intermediate orifice whereby to separate the core and shell materials, said liquids being subjected to natural forces of gravity, capillarity and surface tension.

19. In the process of forming a composite capsule by natural drop formation, the step which includes successively initiating the flow of shell,

lining and core liquids from concentric orifices progressively spaced in the direction of fiow, said liquids being subjected to natural forces -01 gravity, capillarity and surface tension.

20. The process of capsulation' which includes the steps of discharging a quantity of acongealable lining, material into a body of congealable gelatin, simultaneously discharging a. liquid core material into the body of lining material, subjecting the materials to natural forces of gravity, capillarity and surface tension to forms. composite drop, and cooling the drop to congeal said lining material and gelatin, the lining material separating the core material from the gelatin.

21. Apparatus of the character described having, in combination, three means for discharging heated shell and lining materials and cooler core material from the outer, intermediate and inner orificesrespectively to form a composite drop that falls from the outer orifice, the discharge of shell material being prolonged beyond the interruptlon of lining and core material, and a body of cooled liquid oi lower substantiallycomplete' discharge of said and core materials and during the final discharge of the shell material.

22. Capsulating apparatus comprising a nozzle having a plurality of spaced metal tubes nested together to provide three concentric/orifices in a tube of insulation disposed within the inner metal tube and having a longitudinal opening, the latter metal tube extending beyond the end of the insulation tube and having a longitudinal opening inner orifice and being a continuationof the opening in the insulation tube hrough which two-openings cooled core liquid passes the space between thelnner metal tube'and the next butwardly spaced metal tube forming a passage i'or lining material, and the. space-between the last mentioned metal tube spaced metal tube forming a passage for shell concentric orifices.

forming the and the next outwardlymaterial, a common. metal support for said metal to prevent premature congealing of the shell and lining materials at their respective nozzle orifices.

23. .In capsulating apparatus, the combination of an insulating tube having a longitudinal bore, a metal tube enclosing the insulating tube and having an end portion extending beyond the end of the insulating tube and having, a bore in alinement with the bore in the insulating tube, the bore in said end portion forming an inner orifice. for receiving and discharging cooled core material from the bore of the insulating tube, a second metal tube spaced from the first mentioned metal tube, and forming therewith a lining material orifice, a third metal tube defining a passage around the'second metal tube and forming a shell material orifice, and means for heating said metal tubes to prevent premature congealing of the shell and lining materials at their respective orifices.

24. In capsulating apparatus of the character described, a nozzle comprising three tubes nested together to form three concentric orifices in spaced apart relation for discharging core, lining and shell liquids, and a ring outside of the outside metal tube and spaced therefrom to form a.

.capillary chamber.

CARL E. IVIABBS.

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