[1]Patented Fe'b. 139 1940 2@190@479 PATENT OFFICE UNITED STATES 2,190,479 METHOD AND MEANS FOR MAKrigG CONTAINEITS George ArRucton Moore, Louisville, Ky., assignor to Humoco Corporation, LouisviUe, Ky., a corporation of Delaware Appflcation August 16, 1938, @Serial No. 225,113 13 claims. This invention relates to containers and more particularly to methods and means for joining ov6rlapping portions of materials adapted to be adhesively sealed together in an impervious manner for forming articles such as container bodies, for example. It has been heretofore proposed to form junctures, such as in the fabrication of containers or container bodies made of paper and metahic 10 foil and other flexible materials, by the application of heat and pressure for activating , a dry film of thermoplastic adhesive' interposed between the surfaces being joined. A great am.ount of difficulty has been encounteribd, however, in 15- making these junctures sufficiently strong in instances where high speed production is a highly desirable or paramount factor. Another heretofore insurmountable difficulty in making junctures of the above nature has been in consistent20 ly providing an air-tight, moisture-proof seELm or joint, particularly when edges of the material to be joined extend longitudinally or transversely therethrough and when the thickness of the seam varies. The methods of heat sealing here26 tofore us6d generally fail to provide an, air-tight juncture either because the adhesive, especially during high speed fabrication, is not properly and sufficiently activated over the exitire seam surface, or because the activated adhesive Is not so perniitted to set properly or qitcjcly enough. When the adhesive sets too s@owly, as when it. is the parts to be joined are under tension from folding or bending, as the same ordinarily are, 35 said parts separate sufficiently to permit the entrance of air which prevents the desirl@d adherence of the engaging surfaces thereof. IrregWarities in, the materials or seaftg @means and particularly varying thicknesses, such as may 40 be caused by varying numbers of layers of material In different paxts of the joint, have heretofore prevented the application of sufficient sealing pressure at all points along the joint, and minute holes or unsealed sj>aces along the seam, 45 which permit the passage of air ind moisture, have accordingly resulted. It is necessary, in order to obtain proper activation of the adhesive, that the sealing iron have intimate contact with the seam throughout its entire length. Accord50 ingly, under present methods, the slightest distortion of the con'tact surfaces of the sealing irons or the surfaces against which the same operate may result in an unsealed spot and hence a seam which wfll permit the passage of adr and. g5 moisture. Difficulty ha@ 41so been experienced (Cl. 93-36) in preventing pocketed vapors, generated during the application of heat, from parting the -seam before the adhesive has time to set. It is therefore an object of the present invention to provide a novel method for consistently 5 producin g, at high speed, heat-sealed junctures which are strong, durable, and Impervious to both air and moisture. Anoth er o]iject of the inv6ntion is to provide novel means whereby the novel method above 10 referred to may be effectively and inexpensively practice d A further object is to provide a novel method and means for insuring quick and proper activation by heat and pressure of a dry adhesive sub- 15 stance interposed between the two surfaces to be joined thereby. Still @nother object is to provide novel means and method whereby the irregularities and varying thicknesses in heat sealed junctures may be 20 compens ated for, to thereby insure sealing at all points and hence the hermeticity of the junctures. The above and further objects and novel features , of the invention will more fully appear 25 from the follgwing detailed description when the same is read in connection with the accompanyIng drawing. It is to be expressly understood, however , that the drawing is designed for the pwpose of illustration orily and is not in- 30 tended to define the limits of the invention, refpose to the appended claims. In the drawing, wherein like reference characters refer to like parts throughout the several 35 views, Mg. 1 is an end elevation, partly in section and with parts broken away, illustratirig olie form of apparatus for carrying out the novel method Gf the invention; 46 Fig. 2 is a similar view showing the sealing iron in operative position; Mg. 3 is an enlarged side elevation of said apparatus, partly in sectibn and with parts broken away, the section being taken substahtially on 45 line 3-3 of Flg. 2; Flig. 4 is an isometric view of one type of container body wwch may be formed in accordance with the present invention; and, Figs. 5, 6, 7 and 8 are cross-sectional detail 50 views illustrating various types of seams or Joints which may be formed in practicing the method of the invention. The novel means and method comprehended by the present invention are shown in the dmw- 56 not removed from the influence of heat, and erence being primarily had for this latter pur-
[2]ing and hereinafter described, by way of example, in their application to the making of tubular container bodies from blankq of flexible material, such as paper and metallic foil. It will, of course, be understood that the invention may be practiced in forming Junctures between the above and similar materials for any purpose *hatsoever. A preferred type of container body which may 10 be made in accordance with the present -invention and which may be employed in making a container of the type disclosed in the copend.ing appheation of George Arlington Moore, Serial No. 153,705, ffled July 15, 1937, is consti15 tuted by a single laminated blank having an iiiner layer 10 of fibrous material, such as paper, and an outer layer I I of impervious material, such as metallic foil (Flg. 5). The outei foR surface of blank IO, II Is preferably coated over 20 its entire surface with a thin dry ftlin of thermoplastic lacquer or other siniflar substance having potential adhesive properties. One type of lacquer which has been found suitable for this purpose is Beckwith-Chandler Co. Lacquer No. 25 017308, a lacquer having a sords content of about 26%. The side margins of the blank are preferably folded inwardly to form hems 12, 12 (Mgs. 3 and 4) and a marginal portion at one 30 hem 13 for the purpose of providing the flwshed container with metal-to-metal eldsure seams in the manner more fully disclosed In theabovementioned copending application. U desired, the hemmed marginal portions of fibrous lamina IO may be coated with a thin dry ftlm of thermoplastic adhesive, such as -Pliolite, a chlorinated rubber produet, for securing the lnfolded portions of hems 12 and 13 in place. The tubular body (Fig. 4) may be formed from 40 blank IC, I I by folding the latter, preferably around a mandrel or arbor, with the ends thereof qverlapping and sealed together to form a longitudinal side seam 14 by the application of heat and pressure- which activate the thermoplastic 45 fllms previously applied to the engaging surfaces of the overlapping portions and press the sanie into the interstices of the material. As shown in Fig. 5, the foil surface of the infolded portion of hem 13 is brought into contact with the foil sur50 face of the opposite end of blank IO, I I and the overlapping portions of the two ends are substantially twice the width -of said hem. It wiU be seen that, In the longitudinal side seam of the tubular body thus formed, the portion of the 55 seam between the inner edges bf hems 12 at oppo8ite ends of the body Is made up partly of three, thicknesses of the blank and partly of two thicknesses thereof, as best seen in Flg. 5. Adjacent each end of the body, where the sid6 seam con60 tains hem 12, said seam is made up poztly of six thicknesses of the blank and partly of - four thicknesses thereof. It wiH be obvious that a seam of this character is difficult to seal in an impervious manner since 66 the thicker portions thereof prevent the hot sealing iron from coming into intimate7 contact with, and applying a sufficient pressure to the thinner portions of the seam. Additionally, the particular seam or joint described above has an edge 15 To of blank IO, II extending longitudinally thereof and the inner edges 16 (Mg. 3) of hems 12 extend transversely therethrough. Heretofore, it has been substantially impossible, even when comparati -ely thin stock was employed, to adhesively. IS heat sei I a seam so as to prevent the leakage of end of the blank is f6lded to form a 2,190,470 air and moistuxe along edges of the ifiaterial passing through the seam. Inequalities in the thickness of various portions of the blank itself and the difficulty of maintaining the sealing iron or irons In parallel relationship with the mandrel S or with each other have also been material factors In the failure of others to produce air-tight, adhesively sealed Junctures. The heating anvil and mandrel can very eas ' ily have or develop slight Inequalities in their contact 10 surfaces which prevent the making and maintaining of intimate contact between tije seam and,anvil, and very slight distortions or irregalarities in the anvils or mandrels will leave spots along thi@ seam which are not ptoperly activated. is Where air is preseni in the seam as a result of insufficient contact and pressure, the adhesive cannot be properly activated. Efforts have beerl made to compensate for the above Irregularities by contouring the face of the sealing irons or go mandrel, but it Is impossible as a p@actical matter.to get consistent registry With the neressary. accuracy between the material and the machine parts. Another factor in the failure of others In their W. endeavors to provide an iml*rvious, adhesivel@r sealed Juncture betw'een engaging surfa . ces of fibrous or like materibls has beezi their failure to properly control the flow of. heat employed and the storage thereof. Flor example, heat bealed 30 Jtmctures have been -made heretofore by employing two substaritiallyi equally heated seaung Irons pressing ag t op ains posite sides of the seam or by employing one hot sealing iron and a cold mietal backing plate or mandrel. In the first'N Instance, there is lio actual flow of heat from one heated iron to the other through the adhesive fums ilnd such flow is necessary to get-.quick and proper activation of the dry Mms of adhe-' SiVe. The heitt flows from both sides to the center, thereby caus*9 such an accumulation of vapors that the @gaseous pressure ruptures the seam or causes blisters as soon as the pressure of the iron is released. Also, when two equally heated irons are used, the fibrous miterial be- 45. comes very hot and, being a poor conductor of heat, retains the.same for an appreciable period after withdrawal of the heating irons, thereby preventing quick setting of the activated adhesive. In 'th6 second method mentioned above, So the heat flows, so rapidly from the hot Iron to the cold iron tliit the adhesive Is not activated until a considerable amount of heat has been absorbed by the cold iron, unless such a high degree of heat is employed that the lacquer coat- 65 Ing on the outer surface of the material is decomposed, thereby detracting from the appearance of thelcontainer and, at times, fourng the sealing irons. In high speed production, a properly heoted. sealing iron cannot ordinarily be eo held in @ontact with the s6am sufficiently long to prol*rly activate the adhesive under these conditions and when the seam, after the formation thereof, rem.ains in contact with the Initially cold Iron, such as a mandrel, the large quantity of 6 r), heat absorbed by.the latter prevents quick setting of the adhesive which has been Activated. When qiiiek setting Is not obtained, air tends to enter the seam @ and the engaging portions thereof, being un.der some tension, tend to puU 7o apart. I A novei method and novel means for practicing the same 6,re accordingly provided by this invention for overcoming the, foregoing diffleulties. In the embodiment shown, said novel means com-
[3]2,190,479 prbes a raet&Mc mandrel or arbor 17 of rwtan. gwar@ crowawtion which, rA&y be &Udably mounted on a support 18. Along the fade of arbor 1 17 against which the overlapping ends of 6 blank IO, I I are pressed durim the seam among ope;ration, uUd arbor is provided with a longitudinally extending ;ece83 1,1 In which a pressure equaliiing pad' or element 21 Is 2rmly embedded. Said pad Is, of a resWe4.t, yielding, 10 nature and preferably comprim an outer filee of rubber vwcomized on a fabric ban. One sultable mews for wrapping blank II. I I about mandrel 17 is illustrated and desexibed In the copending application of Gwrge Arlington 15 Moore, Serial No. 173,101, Med NoVember 6, 1937. A portion of said means, shown in phantom L In Plg. 1, comprises a plate 21 for holding the cen,,tral portion of the blank against the lower face ,of arbor 17, a pair of blades 22 for folding the 20 ends of the blank upwardly against opposite sides of the arbor, and members@23'and 24 for 'folding the ends of the blank inwardly agowt the upper face of the arbor and Into overlapping relation directly above pad 206 25 In order to activate the adhesive film dispgsed on the engaging surfaces of the overlapping ends of blank 10, I 1, the lapped portions are engaged and pressed together by a seaung iron 25. The latter may be heated by any suitable ineans, elec80 trical hee@ting means being employed in the illustrated e'mkodiment. The heating cartridge is removably mounted In iron 25 and comprises a heating coil 20 wound on a suitable core and surrounded by a,,ma gnesium-,insulator 27 itnd a m@t@llic casing 28. Cooling fins 29 are provided on iron 25 for minimizing the tmmfer of heat from the latter to the supporting means therefor. For a purpose to appear hereinafter, the face of iron 25 is relieved or recessed at the oppo40 site ends thereof so that hems 12 will not be 6ubjected to material heat.and pressure and to provide for the passage of yieldable fingers 30 which serve to hold the overlapped ends of blai2k IO, I I in position during the descent of iron 25 . If de45 sired, flngers 30 may be Integral with plate 24, which prefeirably extends substantially the f'ull length of arbor 17 or said fingers may be onutted. ftom the disclosure of lmgs. 2 1 and 3, it will be fo seen,, that pad 20 yields under the pressure of the sealing iron and ijresent@ a pressure resisting face which permits the application of a,substantial pressure to all parts of seam 14 irrespective of the varying thickness thereof and 55 irrespective of any misalignment between the operating faces of the arbor and heating iron. The yielding of pad 20 compensates for the variations in the thickness of seam 14 and causes the layers to be pressed into close Lconts@et with the So edges of material in the seam, such as edge 15. There will be a unidirectional.flow of heat from. iron 25 through seam i4 and since pad 20 is a poor conductor of heat, said flow will be at a suffici6ntly low rate so that the adhesive film 65 will be quickly and adequately activated and pressed into the interstices of the material. Additionally, pad 20 absorbs little, If aixy, heat during the short heating Interval and accordingly does not hamper the substantially instantaneotit TO settixig of the adhesive after withdrawal o% the setting iron. In one embodiment@ of mechantain which has been constrlicted for carrying out'the method of the present invention, it has 'been found that, in forming a Junctute of the.particustaud. an efftelent tempemture for iron 25 Is from 400- to 4500 PWnmbdt when the contact period li approximately one,.pwond and the pre-sawe applied Is from 1500 to. 2000 pounds. In se&Ung spun of the character of seam 14 which embodies multiple folcia, it has been found in practice that, if the entire seam is simultaneously pressed by the sealing Iron, gases will be f6rmed and trapped within mdd folds stnd cause blisters or ruptures the moment the exter- 10 nal sealing pressure is released. If blisters are formed without causing a rupture, the trapped gases are very- apt to cause ruptures upon further folding of or application of pressure to the blistered portion. The gases referred to are formed is principally from air ttapped within the folds when the sealing iron abruotly and quickly @ngages the entire area of the seam, and by the vaporization of the normal moisture content of the fibrous component of blank It, II, It being Si) necessary that the fibrous material contain some moisture in order to obtain best results in the working thereof. In the particular embodiment of the sea'm shown in Plg. 4, for exai@ple, it cim be readU7 25 seen from PU. 1 that, if sealingiron 25 moves rapidly, as It does in practice, Into contact with the entire area of seani 14, air WM be trapped within the spece adjacent edge II of hem 13 azxd within thp. folds of hems 12 and 13. Additionally, @90' the heat'from Iron 25, does not flow throuih'. 'ifie multiple thickness of said hems as rapidly as it does through the two-ply portions of the seam so that said-littter portions might be sealed together befdre the formation of moisture vapor W Occurs in the. hem folds, th6r6by cutting off any, avenue of escape for said vilpor. Air and vapor in prohibitive quantities may accordingly be trapped within..the seam and destroy the lmPervious ness of the same or cause blisters there- 40. 1!@ after the release of, the 6xtemal sealing pressure and before the activated adhesive has a chance to set, it being impossible for these gases to escape through the non-porous, non-absorbent metallic lamina;tion II witliout, rupturing the 45 salne. In order, therefore, to Insure the imperviousness of seam 14, the face of iron 25 Is preferably so shaped or conioured that heavy pressure is applied only to the U-shaped area of said seam 50 which Is bounded by hnes a, b, c, and d. (Flg. 4). A lesser presgure is applied to the area 14g, which is bounded by Unes a, and b, thereby I)roviding a vldnt for the gases referred to above. The pressure applied to area 14a is 1)referably only suf- 55 flcient to tack the single-play overlapping L-nd of blank 10, I I In position. 7be marginal end areas of, seam 14 beyond the lines 0 are preferably noi pressed and subjected to heat for the additiona l reason that it is highly desiroble to 00 avoid any ill effects of the heat on the adhe@ive coatings on the inner surfaces of hems 12, which coatings are to be subsequently employecl for heat - seaung th6 ends of the tubular body. It wiU be understo od,,however, that pressure and heat inay 65 be ap@lled to the ends of seam 14, It desired, to seal the sanie at the same time that the centmi Portion of said seam is sealed. Additionally, the face of sealing iron 25 may be ribbed so as to press one or more longitudinal flutes 31 (Eng. 4) TO in thecentral portion of seam 14 to further Insure th.e hermeticity thereof. . In Figs. 6 and 7, there are shown two alternative types of seams or junctures which may be Tg lar type described and embodying the materials mad6 by practicing the present Invention. In To
[4]2,190,479 Mg. 6, the inetal lai@iina I I' is shown on the inside of the body and.fibrous lamina 101 on the outside. In Mg. 7, a simple paper-to-paper seam Is shown. @ Mg. 8 illustrates one manner in which the ends of the body of Mg. 4 may be sealed. The opposed halves of the inner face of hem 12 are pressed Into @ontact and heat sealed by the applic'ation of heat and pressure. 10 There is thus provided a novel method and m,eans whereby variations in thickness may be readily and automatically compensated for in the formation of heat sealed Junctures between flexible materials, such as paper iind foil. A 16 novel means and'method are also Prov@ded for insuring proper activation and quick setting of a heat activated adhesive in a Juncture of the above type. . Although onl3@ a single embodiment of the In20 vention has been illustrated and described in detail, it is to be expressly understood that the sanie is not limited thereto. - Various changes may be made, for example, in the design and arrangement of parts illustrated and In the mate26 rials sp@ecified without departing from the spirit and scope of the Invention, as will now be apparent to those skilled in the art. 'For a definition of tiie limits of the invention, reference is had primarily to the appended claims. 30 What is
