US2428911A - Method and apparatus for producing capsules - Google Patents

Description

R.,w. GUNNELL 2,428,911

METHOD ZAND APPARATUS FO-R PRODUCING CAPSULES v Filed oct. 19",' 194e f y Sham-sheet 2 *Oct 14,1947.

on ooolnngqQoOoooOoOoooO oonoooooooncooo ooooaooocoo'onu o oooooQonoooOoooo @few @M Oct, 14, 1947.. `R.;w. G'UNNELL METHQD' AND APPARATUS Fon 141013110111@4 CAPSULES Filed Oct. 1,91 1946 4 sheets-sheet 4- fem/z: W. 7am!!!- K I INVENT Patented Oct. 14, 1.947`

METHOD AND APPARATUS FORPRODUCING-L CAPSULES Robert W. Grinnell, Detroit, Mich., assi'gnor fo Industrialr Sound Systems, l Inc,

Cleveland,

Ohio, a corporationr ofy Ohio Applicationoctober 19, 1946, Serial No. 704,476

17 Claims.

This invention relates to the manufacture. of capsules, and'among other objects, aimsto pro- Vide an improvedapparatus and'method for producing capsules containing various content substances such aslmedicaments.

The nature of the invention may be readily understoodY byre-ference to. one apparatus embodyingthe invention andrshovvn in the accompanyin drawings.

In said drawings.:

Figure l is airontv elevation of theapparatus;

Figure 2 is a. plan view thereof;

Figure 3` isa side sectional elevation of the upper portion of the apparatus-taken onthe plane 3--3v of Figure 21;

Figure 4 is a side elevation of the apparatus vie-Wed fromthe left handsideof the apparatus as shown in Figure 1V;

Figure 5 is a section on an enlarged scale of a discharge jet and associated elements ;V

Figure 6 is: a detail, section through aV header takenon the plane 6.-51 of Figure 1; and4 Figure 7 isV alfragmentary side elevation of an alternate form of the apparatus embodyinga single cooling jacket commonvr to the several tubes which supply contentirnaterialto the nozzles or orifices.

According to the illustrative apparatus; the content substances to bef capsul-ated are formed into globules or pellets; lpreferably ofV measured or predetermined volume and covered with a capsule-forminglm or shell such as gelatin; The content substance may advantageously be in liquidl form in which case they may be released in liquid globules or drops- Which, due to their inheren-t. surface tension; .form into spherical shape. OntheA globules or pel-lets a. capsule or coating is formed by selidifying or otherwise setting thereon a retaining lm or shell oi coating substance, The expression drops is used in a general sense and not to define a specific volume of content substance; In! the illustrative apparatus, the globules or pellets are introduced into a coating liquid (such as gelatin sol) thatl is, a liquid co-ntaining gelatin' (comprising the capsule-forming material) andrcollect thereon a shell or coating which constitutes the' capsule. The globules or pelletsv are caused to travel through the coating liquid', preferablyautomatically, andrfor that purpose the latter is adjusted to have a different gravity from that of the globules or pellets. In the'present. case, the coating liquid has a specific gravity greater than that of the content substance so that the globules of the latter will rise in .the coating liquid. 'For capsulating with a y Y thermoplastic coating material, the contentsub- Y purpose.

stance is preferably chilled before being introduced into the coating liquid and the latter is n maintained at such temperature that a coating of the liquid will set o-r congeal on the globules as they pass, in this case rise, through the liquid. The temperature differences between that of the globules and the coating liquid depends on the amount of cooling necessary to congeal an adequate lm of coating on the globules.

The coated globules are removed from the cap.- sulating material before the latter has an opportunity to affect (i. e., melt in the case of, gelatin) or otherwise` impair the coating. The resulant capsules are seamless and therefore cannot develop leaks kas in the seamed capsules heretofore on the market. In the present case, the capsules are separated from the coating liquid andfrom each other by passing them through an adjacent body of liquid immiscible with the gelatin sol` and Which advantageouslyconditions or treats the capsules in this case by further hard' ening the coating orA shell, so that the capsules Wil1`not cohere and maybe readily handled.

In the illustrative apparatus for. performing the aforesaid operations, the content substance in liquid form is introduced into a chamber Il) containing the capsulating substance in liquid form through a plurality of discharge nozzles, orifices or jets. Il located atthe bottom of chamber lil. It will be noted that the nozzles or orices Il project into the chamber I0 and the discharge ends thereof preferably project into the layer of coating liquid above the bottom of such layer. As here shown (Figure 4), the discharge orices ll are arranged for convenience in a pair of rows. Each orice is advantageously connected to a separate supply line I2 which leads from a metering pump or supply means (not shown) for delivering or forcing the content substance through the tubes at such predetermined rate as to cause globules of the content substance to form in the discharge orifices I lof the proper size and at the desired rate. Any appropriate metering pump or other measuring device may be'employed for this Solid or semi-solid pellets of content material are of course introduced'into the coating liquid much more simply. As will presently appear, it is preferable if these also rise so that they will leave the coating liquid' at its upper surface.

In this case, the content substance is conditioned to the proper temperature before issuing from the orifices by passing the same through a cooling device here. shownfin theformof upper and lower headers I3 and I4 connected by tubes or jackets I5 which surround pairs of the rising tubes I2. A 'fluid refrigerating or cooling medium is introduced into the lower header through line I@ and leaves through line Il. As shown in Figure 7, a single jacket Iia common to all oi the tubes I2 may be employed instead of individual jackets for pairs of rising tubes I2 and by the use of va. common jacket, the temperature of the content material passing through the tube I6 may be more efciently controlled. Whether the jacket I5 or common jacket Ia is employed, it is desirable that the refrigerating jacket extend into close proximity to the orifices or nozzles Il so that the content material discharged from the orilices will be accurately maintained at the desired temperature.

For coating with gelatin, the pellets or globules, as the case may be, are advantageously cooled to a temperature of 10 to 20 F. The gelatin solution is maintained in a thoroughly fluid condition by holding it at temperatures from 120 to 150J F. and this assures the formation of an adequately thick shell on the globules. It will be understood that the temperature of the gelatin or other coating material used, depends on the thermal characteristic of the coating liquid. Various types or grades of gelatin sols or other coating liquids require different temperature conditions, depending upon the melting or setting point of the coating used.

The orifices Il are advantageously provided with closing means in the form of slidable pins I8 to i'ill and close theV orifice when the apparatus is not in use to prevent gelatin from congealing in or otherwise clogging the orice. An appropriate closing device is illustrated in Fig. 5. As there shown, the tube I2 after issuing from the upper header I3 enters a fitting I9 fastened to the bottom 2i of the chamber l0 by means of a shouldered nozzle tip 22 screwed inside the fitting and clamping the intervening bottom toform a leak tight joint. The passage 23 connects the tube I2 with the orifice I I. Also threaded into the lower end of fitting `lil is a regulating valve 2d in alignment with the passage 23 surrounding pin I8 Whose extremity 25 is adapted to move into and ll the passage 23 and orifice I I when the apparatus is not in use. A knurled enlargement 22S on the valve 24 facilitates rotation of the latter to adjust its extremity 2l relative to the seat 25 to supplement the regulation of the flow of content substance and to insure discharge of globules of equal size from all of the orices Il. Such regulation is simplified by incorporating sight windows 29 in opposite sides of the chamber to expose the discharge of the globules from the orices for inspection. A packing nut 3l covers the extremity of valve 24 to prevent leakage around the pin I8.

The gelatin sol or other coating liquid is maintained at the proper temperature by heating vmeans in the form of a series of electric heating strips 32 which lie parallel to the rows of oriiices, The heating elements are controlled by an appropriate thermostat or regulator 33 located inside the chamber I0 and responsive to the temperature of the coating liquid. A thermometer Sli also advantageously indicates the temperature of the coating liquid.

After passing through and therebyreceiving a coating from the coating liquid, the globules are separated from the latter and are advantageously further cooled and otherwise treated to harden or set the coating suiliciently for handling and to prevent cohesion. In the present case, they rise through a supernatant body 35 of conditioning or separating liquid Which floats on the body of coating liquid. The separating liquid is lighter than the coating liquid and of such character as to be immiscible therewith. For convenience the conditioning and separating liquid has been termed a cooling liquid in the claims, but it should be understood that its function is not always or solely one of cooling.

For a gelatin sol, a separating liquid comprising a light hydrocarbon such as kerosene, naptha, petroleum ether or the like, mixed with carbon tetrachloride or a chlorinated hydrocarbon such as perchlorethylene, is employed. The mixture is made in such proportions 0f the light and heavier components as will have any desired specic gravity, ranging from about 1.025 to about 1.055 at 60 F. For other coatings the separating liquid should be such as not to impair the coating.

The preferred specific gravity is such as to insure iloating of the conditioning liquid upon the coating liquid employed and yet provide the buoyancy required to cause the capsules to rise therein.

The coating liquid may range in specic gravity from about 1.070 to about 1.100 at F., depending upon its composition and the concentration of gelatin or other base. For example, when the coating liquid employed is a gelatin sol of 1.080 to 1.090 specic gravity at 130 F. the separating liquidV preferably is of 1.020 to 1.050 specio gravity at 60 F.

One illustrating gelatin coating'sol comprises:

Per cent by weight Gelatin (15) to 250 Bloom) 2l Glycerine '7 Water Balance The glycerin is employed to reduce the brittleness of the gelatin in the capsule. It is added in the amount of about thirty to forty percent of the weight of the gelatin.

A harder capsule material may be obtained by increasing the gelatin in the above sol to twentyfour percent and the glycerin correspondingly, i. e., to 9.6%.

If the content substance be heavier than the coating liquid, the former may be coated by down- Ward travel through the liquid. In that event it will be desirable to use a cooling liquid at higher gravity than the coating liquid so that the latter will float on the former. If a buffer or insulating layer be used, it should, of course, be lighter than the lower liquid and heavier than the upper, and immiscible with both, Completed Capsules may be removed from the bottom of the receptacle by hand, by suction or by a mechanical conveyor.

For conditioning the capsules, the separating liquid is such as to cool or set the coating on the capsules adequately as the latter rises through it. In the case of a gelatin sol coating liquid, temperatures of from 40 to 60 F. for the separating liquid are adequate. While the average temperature of the conditioning liquid is lower than that of the sol, the heat of the latter supplied from the heater elements 32 is sumcient to maintain the temperature at the inter-face between gelatin and conditioning liquid suiciently high to prevent congealing of the gelatin at the inter-face by the conditioning liquid. For this purpose, heater elements 32 advantageously extend through the inter-faces 30 between theliquids.

Where it is desired tofobtain' specially' thicker hard. capsules by the-.- use of a solution? ofi high gelatin or other: base concentration, and corriespondinglyl high meltingL or' setting pointpcongealing atv the: inter-face: which. might otherwise occur;y is prevented: byV interposingalayer of an intermediate or buffer. liquidibetweenfthercoating solution'. and. they conditioning liquid and immiscible withboth. Such-a layer of intermediate4-solution of specific gravity lower than that of the coating liquid and higher than' that of, the conditioning. liquid, floats upon theY surface of the coating solutionand protects or insulates it from direct` contact with the: cold' convection. currents descending in the supernatant conditioning. liq.- uid- Thepresence of an intermediate liquid layer also perrrnitsv the-use of'. a conditioning liquidwhich would be miscibleA withy the coating liquiddf they were in contact.

In; such case the intermediate layer may have the composition; above described for. the conditioning liquid, and theuppermost liquidt may con sist of water alone or water to whichiv alcohol, ace'- tone.,. or other soluble substance which: will not attackor affect the capsules, may be added to control and regulate the specic gravity within the` range of about .985- to about 11010 at 60 F; At the low temperatures-of theconditioning; liq.- uid, water doesfnot. aifect thegelatin of the cap;- sules.

Free passage of the ascendingcapsulesthrough the interfaces between the various solutions described above is facilitated by the addition to such. solutions of small. amounts of those sub*- stancesv which reduce `inter-.facial tension. These substances maybe ordinary soa-ps or any' of the well-known wetting agents such as the sul-'- phonated derivatives of the higheralcoholasalts of the'sulphonated alkylzar-yl compounds and the like. They are added to-any orfeachof the above solutions in amountsv preferably ranging from about. 017 to about .25% of' the weight of'. the-solution, depending upon the practical effective.- ness of the particular wetting agent. employed'.

The conditioning' liquid is maintained: at the proper temperature by cooling cells 36 in the formy o-f hollow plates; which in this caselie'parallel. toandv on opposite sides of the paths traveled by thev ris-ing capsules. The cellsy are 'connectedin. series by the conduits-31 and 33, A--liquid refrigerant or. a cooling medium: enters the first cell through the pipe 39 and leaves the last cell throughthe pipe'tl, Appropriate-means (not shown) for eooiing and. circulatingv the' refrigerant. through the cells areprovided'.

Whenthe capsules reach thesurface 42 ofthe conditioning-liquid; they areremoved, in this case, by a discharging devi-ce in the' form of arotating. paddle wheel 43l carrying a plurality of ngers 44 which rake the globules to the overflow Weir 45- and cause them to rolldown a perforated draining plate 45 into acollecting receptacle 47. The conditioning liquid: adhering to the capsules drains through the plate intothe collecting chamber 48 as also` does theY liquid which: ows over weir45. From this chamber, the liquidiis withdrawn through line. 49 by pump 5.!)v and recirculated, iirst passing through a. cooling unit ft in the form of a coil 'immersed in a vessel -containing a' cooling or refrigerating medium; From therefrigerating.` unit the Cooled conditioning liquid isk carried through pipe 54 and discharged. through branch pipes 55f-whose `extremities ii-lie on opposite sides-of the center cooling cell 36 and are provided with upwardlyopening 6. orificesy 511 which induce an upwardly traveling circulation of the conditioning liquid in the chamber 58a A thermometer 59 advantageously lindicates the temperature of the conditioning liquid atits surface.

The paddle wheel 43 is rotated in this instance by a= pulley 5|I towhich anl appropriate driving means, not shown, is connected;

The hydrostatic head of the conditioning liquidv is balanced in the present instanceby a stand pipe 62 connected with the coating liquid supply. Since the conditioning liquid has a lower gravity thanthev coating. liquid, the. level of coating liquidinthe stand pipe issomewhat below the level. 42- of= the conditioning liquid. Additional. coatingliquid is introduced` in the upper end` of the stand pipel621. For. that.purpose,.a supply charnber 631s provided.wherein a. substantially constantflevelI 64. of. coating liquid is maintained'.

The coating. liquidi is. elevated to the proper temperature by anY electric heating element 65 inside-the receptacle 55 which is closely adjacent toY the chamber. lo and connected thereto. by pipe .61. The stand pipe 62 enters the upper end. of. chamber lii` A thermostat or other thermo-regulator 68 inside the chamber 6B controls the heater elements G5 to maintain a predei,`ermined`y constant temperature for'the supply of coating liquid. This temperature is advantageously indicated by thermometer 69 within chamber. 66.- Preheating of the coating liquid asA aforesaid reduces the loadon. the heater elements B'Zinchamber I0 and thereby makescloser temperature regulation. possible.

The foregoing method. assures the formation of a coating. or shell. of uniform thickness re.- gardlessof. the relative grax/'ities of coating liquid and content. substance. The coating. isformed by congealing the coating liquid. on the content substance progressively. The coating substance does. not become a. coating untilit has congealed inwhich-condition it cannot shift, and additional coating.. does not build upI until the underlying coating hascongealed. Since the globulesof con.- tent substance are of. uniform temperature throughouhlthey abstract heatfrom the adjacent coating liquiduniformly tnroughthe surface and therefore a. coating of. uniform thickness is. built upon the globules.

This application is a continuation in part of my application. Serial No. 522,716, filed February 1'7, 1944, and entitled Manufacture of capsules.

Obviously, the invention is not limited to the details of the illustrative apparatus since these may be variously modied. Moreover, it is not indispensable that. all features of the invention be` used. conjointly since various features may be used.. to advantage in dierent combinations and sub-combinations;

What I claim is:

l. The method of fabricating capsuleswhich comprises introducing' into. a capsule forming liquid the content substance at temperatures'below.4 tlie congealing point of the capsule forming liquid soVV that the content substanceV will congeal thereon a coating of congealed capsule formingl material, causing the coated content material to pass out of the coating liquid into a body of cooling liquid whose temperature is belou7 that ofthe coating liquid and insulating the coatingliquidlfrom the cooling liquid by. aliquid layer immiscible with both coating. and. cooling liquids.Y

2. In capsule forming apparatus, the combination comprising a chamber having therein superposed layers of capsule forming liquid and cooling liquid of different gravity and immiscible with each other, means for introducing content substance into the coating liquid and causing it to pass in succession through the coating and cooling liquids, said coating liquid having therein a wetting agent to reduce the surface tension at the inter-face of the coating and cooling liquids.

3. In capsule forming apparatus, the combination comprising a chamber having therein superposed layers of capsule forming liquid and cooling liquid of different gravity and immiscible with each other, said cooling liquid being lighter than the coating liquid so that it floats thereon, means for introducing content material, into the coating liquid and causing it to pass through the coating liquid and then through the cooling liquid, said coating liquid containing a surface active agent to reduce the surface tension at the inter-face of the coating and cooling liquids.

4. Apparatus for fabricating capsules comprising in combination a chamber having therein superposed layers of coating and cooling liquids, means for maintaining the temperature of the cooling liquid lower than that of the coating liquid, and a buffer layer of liquid between the coating and cooling liquids and immiscible with both and of a gravity intermediate that of the cooling and coating liquids, and means for introducing content substance into the coating liquid and causing it to pass through the coating liquid and into the cooling liquid.

5. Apparatus for fabricating capsules comprising in combination a chamber having therein superposed layers of coating and cooling liquids, means for maintaining the temperature of the cooling liquid lower than that of the coating liquid, and a buffer layer of liquid between the coating and cooling liquids and immiscible with both and of a gravity intermediate that of the cooling and coating liquids, said coating liquid having therein a surface active agent to reduce the surface tension at the inter-face of the coating and buffer liquids, and means for introducing content substance into the coating liquid and causing it to pass through the coating liquid and into the cooling liquid.

6. Capsule fabricating apparatus comprising in combination a vessel containing liquid capsule forming material, a series of supply lines conriected with said vessel and leading directly to the capsule forming material for introducing the content substance into the capsule forming material, and a refrigerating jacket aro-und said supply lines to cool the content material to a temperature below the congealing temperature of the coating liquid, said refrigerating jacket extending into close proximity to the point where the supply lines lead to the capsule forming material.

7. In capsule fabricating apparatus, the combination comprising a vessel containing congealable capsule forming liquid, said vessel having therein an orifice through which the content material is introduced into the capsule forming liquid, means for introducing content substance through said orifice at temperatures below the congealing point of said coating liquid, and means for plugging said orifices while the apparatus is idle to prevent congealing of capsule forming liquid in said orifice.

8. In apparatus for fabricating capsules, the

combination comprising a vessel having congealable liquid coating material therein, said vessel having a row of orifices through which content substance may be introduced into said coating material, means for cooling the content substance to temperatures below the congealing point of said coating liquid, and heater units in said coating liquid on opposite sides of said row of orifices to maintain the coating material in liquid condition.

9. Capsule fabricating apparatus comprising in combination a vessel containing superposed layers of coating and cooling liquids, the cooling liquid being of lower gravity than said coating liquid, means for maintaining the cooling liquid at a temperature below the -congealing point of the coating liquid, and a layer of liquid between said coating liquid and cooling liquid and immiscible with both and of a gravity intermediate that of the coating and cooling liquids for insulating said coating liquid from the cooling liquid to prevent congealing of the coating liquid b-y the cooling liquid.

10. Capsule fabricating apparatus comprising in combination a vessel containing superposed layers of coating and cooling liquids, the cooling liquid being of lower gravity than said coating liquid, means for maintaining the cooling liquid at a temperature below the congealing point of the coating liquid, means for heating said coating liquid to maintain the same in liquid condition, and a layer of liquid between said coating liquid and cooling liquid and immiscible with both and of a gravity intermediate that of the coating and cooling liquids for insulating said coating liquid from the cooling liquid to prevent congealing of the coating liquid by the cooling liquid, said coating liquid containing a surface active agent for reducing the surface tension at the inter-face of the coating and the insulating layer.

l1. In apparatus for fabricating capsules, the combination comprising a vessel, means for introducing congealable capsule forming material in liquid condition to said vessel, means for introducing into said capsule forming liquid, content substance cooled to a temperature below the congealing point of said capsule forming liquid, means for heating said capsule forming liquid before 'introduction into said vessel, and separate heating means in said vessel for counteracting the excess cooling effect of the content material.

l2. In capsule forming apparatus, the combination comprising a vessel containing congealable capsule forming material in liquid condition, a plurality of orifices adjacent the bottom of said vessel for introducing globules of content substance into said capsule forming liquid. separate lines connected directly to each of said oriiices and having refrigerating jacket means around the same for cooling the content substance to temperatures below the congealing point of the coating liquid, said jacket means extending into close proximity to said orifices.

13, In capsule forming apparatus, the combination comprising a vessel containing congealable capsule Vforming material in liquid condition, a plurality of oriiices adjacent the bottom of said vessel for introducing globules 0f content substance into said capsule forming liquid, separate lines connected directly with each of said orifices for conveying content substance thereto, refrigerating means for said lines extending into close proximity to said orifices, and regulating means for the discharge ci globules of content substance from said orices.

14. Apparatus for fabricating capsules, comprising in combination a chamber having therein two superposed layers of liquids of different gravities, one of which liquids is a coating forming liquid, and a layer of liquid between the two aforesaid liquids and immiscible with both and of a gravity intermediate thereof to maintain said liquids separated.

15. In an apparatus for fabricating capsules, a vessel, means for introducing a capsule forming liquid into said vessel, heater means for maintaining the capsule forming liquid in heated condition in said vessel, a plurality of orifices in said vessel through which content substance may be introduced into the capsule forming liquid, a supply line for content substance individual to each orifice and extending directly thereto, means extending into proximity of said orifices for refrigerating said supply lines, a column of cooling liquid superposed in and being of lower gravity than the capsule forming liquid and through which capsules rise and iioat on the surface thereof, and means for removing capsules from the surface of the cooling liquid.

16. In an apparatus for fabricating capsules, a chamber having therein superimposed layers of capsule forming and cooling liquids of dierent specific gravity and immiscible with each other, a plurality of nozzles in said chamber for injecting content material into the capsule forming liquid, tube means for directing content material to said nozzles, and refrigerating means common to said tube means for cooling the content material passing therethrough, said refrigerating means extending into close proximity to said nozzles.

1'7. In an apparatus for fabricating capsules, a chamber having therein superposed layers of capsule forming and cooling liquids of diierent specific gravity and immiscible with each other, means for heating the capsule forming liquid Within said chamber, a nozzle having its discharge end projecting into the layer of capsule forming liquid at a point above the bottom of such layer, tube means connected to the inlet end of said nozzle for directing content material thereto, and means for refrigerating the tube means for causing cooled content material to be discharged from said nozzle, said refrigerating means extending into close proximity to said nozzle.

ROBERT W. GUNNELL.

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