US2506057A - Means and method for rendering paperboard cartons gastight and packages so produced - Google Patents

Description

y 1950 s. BERGSTEIN 2 506,057

MEANS AND METHOD FOR RENDERING PAPERBOARD CARTONS GAS-TIGHT AND PACKAGES S0 PRODUCED F'lled Oct. 25, 1945 3 Sheets-Sheet l ll/II/I/I/IIIi/I/IIIII/I1 I N V EN TOR.

ATTORNEYS.

May 2, 1950 s. BERGSTEIN 2,506,057

mums AND METHOD FOR RENDERING PAPERBOARD CARTONS GAS-TIGHT AND PACKAGES S0 PRODUCED Filed Oct. 25, 1945 3 Sheets-Sheet 2 'lllll 'I/IIIIIr/I INVEN TOR. 504MB. .BE/[GSTE/N.

ATTORNEYS.

y s. BERGSTEIN 2,506,057

ANS AND METHOD FOR RENDERING PAPERBOARD CARTONS GAS-TIGHT AND PACKAGES SO PRODUCED Filed Oct. 25, 1945 3 Sheets-Sheet 3 BY MW ATTORNEYS.

Patented May 2, 1950 MEANS AND METHOD FOR RENDERING PAPERBOARD CARTONS GASTIGHT AND PACKAGES SO PRODUCED Samuel Bergstein, Cincinnati, Ohio Application October 25, 1945, Serial No. 624,438

12 Claims. 1

My invention relates to the provision of packages made of or comprising paperboard cartons or containers, which packages can be made gastight so as to protect the contents from deleterious external gases or to maintain about the contents protective atmospheres for their preservation. Such packages must be capable of being shipped to the packer in knocked-down or collapsed form, of being handled and used by him substantially in accordance with current methods of filling and sealing, and of being rendered gastight and gassed by simple although dependable procedures and apparatus.

Means and procedures for gassing packages have been set forth in my copending applications Serial No. 557,984, filed October 10, 1944, now Patent No. 2,442,161, and entitled Method of making gas filled flexible containers and Serial No. 553,374, filed September 9, 1944, and entitled Method of gassing filled packages. The gassing and sealing procedures of these cases may be employed in connection with the packages of the present invention.

In another copending case, Serial No. 620,724, filed October 6, 1945, and entitled Gas-tight and gas-filled packages and method of making them, I have taught the formation of a type of package which obviates the necessity of an over-all dip in a thermoplastic substance capable'of forming an integral gas-tight film. It is possible in this way to avoid difliculties of appearance and mechanical weaknesses inherent in over-all films as well as the subjection of the package and its contents to the amount of heat transfer inherent in an overall dip. Again, difficulties are not encountered with expansion of internal atmosphere in the package during dipping. Also, substantial economies are made in the quantities of external film forming substances required.

This application relates to improvements in package involving some of the characteristics of the packages taught in the last mentioned copending application.

Objects of this invention include the attainment of still further economies in coating substance and external web, the avoidance of edge treatments for the paperboard or of after treatments of a longitudinal body seam, and the provision of structures having a greater margin of safety as to gastightness, all as will be made fully comprehensible hereinafter by detailed explanation.

These and other objects of my invention, which will be later set forth or will be apparent to one tions, I accomplish by those procedures and in those constructions and arrangements of parts, of which I shall now describe certain exemplary embodiments. Reference is made to the drawings wherein:

Figure 1 is a plan view of an exemplary carton blank.

Figure 2 is a transverse cross-sectional view thereof.

Figure 3 is a plan view of a blank to which a sheet of covering material has been applied.

Figure 4 is a transverse cross-sectional. view of a portion of the structure of Figure 3.

Figure 5 is an enlarged partial cross-sectional view taken along the line 55 of Figure 3.

Figure 6 is a plan view of the tubed paperboard carton blank of Figures 3 and 4.

Figure 7 is a perspective view of the tubed carton in erected but unclosed form.

Figure 8 i a transverse corner section of the carton of Figure 7 on an enlarged scale and taken along the line 88 of Figure 7.

Figure 9 is a perspective view of the carton of Figures 6 and 7 in filled and closed condition.

Figure 10 is a similar perspective view of the final form of a filled, gas-tight package, produced in accordance with my invention.

Figure 11 is a perspective view illustrating how the treatment hereinafter described may be applied toa carton in filled and closed condition.

Figure 12 is a semi-diagrammatic vertical section of means whereby a sleeve structure may be applied to knocked-down cartons in tubular condition.

Figure 13 is a plan view of a knocked-down tubular carton as so treated.

Figure 14 is a cross-section thereof taken along the line |4l4 of Figure 13.

Figure 15 is a cross-sectional view of a portion of a filled package, taken along the line l5-l5 of Figure 10, and showing means provided for certain kinds of gassing procedures.

Figure 16 is a similar view after the insertion of a gassing means.

Figure 17 is a similar view showing one form of reclosure. I

Figure 18 is a similar view showing another form of reclosure.

Figure 19 is a plan view of a knocked-down tubular carton with which is associated a sleeve long enough to cover the closure flap area.

Figure 20 is a perspective view of the same carton in erected condition, showing the start of skilled in the art upon reading these speciflcathe operation of folding the flaps.

tively flexible character.

Figure 21 is a partial perspective view showing an end of the carton with the flaps closed.

Figures 22, 23 and 24 are partial perspective views showing successive stages in the folding of the sleeve.

Figure 25 is a perspective view of the completed package.

The said copending application Serial No. 620,724 describes a method of making gas-tight packages by forming cartons from a material which is resistant as a membrane to the passage of gas. This material is a gas-resistant sheet material plied to paperboard by means of a layer or integral skin of adhesive substance of rela- It also taught severing such a composite material into sheets, and forming cartons from such sheets by the usual cutting and scoring operations.

The body walls of such cartons, together with the end closure flaps, are gas-tight in the transverse direction. But paperboard is not itself gastight, and in spite of a surfacing of gas-tight sheeting, gas can diffuse through the paperboard in the directions of its length and breadth. No seam or closure presenting cut edges of the composite material will be gas-tight without added treatment.

Hence, it is necessary to practice extra steps for rendering the longitudinal seam gas-tight. This is avoided in the present invention.

In the boxes of the said copending application, the end closures are rendered gas-tight by end dipping, which gives a good result, providing the longitudinal seam has been adequately treated, providing the body of the package is dependably gas-tight, and providing the end coatings seal in a gas-tight fashion with the materials rendering the body of the carton gas-tight.

It has been found in practice that while a satisfactorily gas-tight condition of the composite board as a membrane may be preserved in spite of scoring operations, scoring does not improve gastightness and may. under certain circumstances, be detrimental to it. Failure of packages such as have just been described, if it occurs, tends to occur along scored lines. This difiiculty I avoid in the construction of the present application.

The initial plying of a web or film to paperboard by means of a layer of suitable adhesive, not only involves the use of quantities of these substances to cover the carton flaps, where in the present invention they are not needed, but also involves the inclusion of quantities of these substances in the ordinary carton scrap loss. My present invention avoids these difficulties, keeping the external film or webs and the thermoplastic substance out of the paperboard scrap whereby not only to save these substances but also to prevent a contamination of-the scrap which would render it less suitable for return to the paperboard beaters.

The present invention embodies a concept of what amounts in its most elemental form to a three-part package. A paperboard box or carton is employed to hold the contents and to impart suitably rigidity to the package. The package is rendered gas-tight by the conjunction and combined action of two additional means. The first of these is a gas-tight sleeve surrounding a peripheral portion of the carton (preferably the body walls) and having an independent seam. The second comprises cap-like members enclosing remaining portions of the carton, formed by end dipping or the like, lapping the peripheral portions of the carton body walls, bonded in a gas- 4 tight fashion to the sleeve. as hereinafter set forth, and which may be formed on and bonded directly to any portions of the carton not covered by the sleeve.

In the practice of the present invention, I form paperboard carton blanks in the usual way by cutting and scoring paperboard of suitable weight, which may be printed if desired. No gas-proof character is required in the paperboard itself. The carton blanks so formed may be tubed in the usual fashion and by the usual carton folding and gluing machine. They may, indeed, be erected; filled and closed in the usual fashion and by the usual means. All of this may be done prior to the application of the gas-proofing means with entirely satisfactory results; but this is not usually my preferred procedure.

I prefer to apply to the carton blank or to the t'ibed, knocked-down carton the treatment hereinafter set forth for rendering the body of the carton gas-tight. carton user a knocked-down structure which he may then erect, fill and close in the usual fashion, and which additionally requires only a dipping of the end portions of the carton and the employment of suitable means for gassing it.

The treatment referred to comprises as a first element the application of a gas-tight sheeting forming a sleeve, with a gas-tight longitudinal seam. Since the sheeting is applied to the carton blank, or to the tubed but knocked-down carton, or to the erected, filled and closed carton, the sheeting will be folded or bent but does not require to be scored. It may with advantage be so applied as to cover only the body walls of the carton; but it may also, if desired, cover the flap areas of the carton.

Referring to Figure 1, I provide a knocked-down carton blank of any suitable type, style and size. An exemplary form is that of a sealed-end carton having body walls I, 2, 3 and 4 articulated together by the usual score lines. A glue flap 6 is articulated to the edge of one of the body walls. At the ends of the body walls I articulate suitable closure fiaps 9, III, II, and [2 at one end, and their primed counterparts at the other. This provides a seal-end carton of familiar form which may be tubed by bending it along two intermediate score lines with the adhesive union of the glue fiap G to the body wall i as in ordinary practice. In my package the paperboard carton is relied upon for strength and stiffness, but not for gas-tightness. The adhesive employed in afiixing the glue flap to the body wall may be --any suitable adhesive and need not have gastight characteristics.

The carton, indeed, need not be imperforate. It may be a window carton, i. e. a carton with an opening in one or more walls, in which event a portion of the contents may be visible through the web and skin, hereinafter described, which cover the opening.

Two additional features are of importance and value in cartons designed for the purposes of this invention, but are notlimitations upon the invention otherwise than as set forth in the appended claims. The flaps II and II are preferably cut back slightly along their lateral edges excepting at the ends of these edges, as shown at l3. These fiaps are the ones which will immediately underlie the last folded flaps 9 and 9. As described in my copending application Serial No. 538,764, filed June 5, 1944, now Patent No. 2,412,031 of December 3, 1946 and entitled Cartons for sealing by immersion, the cutting back This enables me to ship to the of the lateral edges of the underlying flaps permits a coating of proofing substance applied by dipping or the like to form a more dependable seal at the carton closure, where the coating is applied directly to the flap surfaces.

Also, where the cartons. are to be gassed by certain processes, as hereinafter set forth, I prefer to form in the carton walls means permitting the more ready insertion of a gassing nozzle or needle. These means may be actual perforations, but I prefer to form them as tiny, depressible tabs, demarked partially by a out line as indicated at II. There may be one, two or more of these means, as required by any particular gassing procedure.

A feature of the present invention involves, as indicated, the application of a web or layer of durable and preferably gas-resistant material, by means of a film or skin of relatively flexible substance to the package in such fashion that it surrounds at least one peripheral portion of the carton and is closed by an independent seam to form a sleeve, and in such a way that the web and skin bend with the carton along the carton score lines, but are not themselves scored. The combination of the web and skin will be gastight. I

The web and skin preferably surround the body walls of the carton, covering at least most of their area. They may terminate at or near the lines of articulation by which the closure flaps join the body walls, and I shall first describe such a structure. Exact surface conformity with the body walls is not required.

The web portion of the sleeve may be a good grade of glassine (which by itself is highly resistant to the passage of gas), or it may be of cellulose acetate, or of ethyl cellulose because of the latters stability under cold.

Other materials may be employed such, for example, as metal foil and glassine laminate. Best results are consistentlyobtained with webs which are themselvesgas-tight or nearly so; but since the web is preferably coated with an integral and imperforate film or skin of thermoplastic substance which may itself be gas-resistant, it is elevated temperature, the internal atmosphere in the gas-tight package will expand, and. passing through the carton walls, may inflate a gas-tight the use of additional adhesive.

possible under some circumstances to use webs which are not highly resistant to the passage of gas, including webs of ordinary papers, providing precautions are taken to prevent the lateral transmission of gas through the porous web in the seam of the sleeve, and at the end closure caps hereinafter to be described.

Successful results may be obtained with a web of material which in itself is thoroughly imper vious to gas and is-formed into an independently seamed sleeve without an interior coating or skin of coating substance. In my preferred practice I employ a web such as glassine and a skin, the skin serving three primary purposes:

First, the skin builds up resistance to moisturevapor transmission by the sleeve, where the web,

as is characteristic of cellulosic substances, is deficient in that respect.

Second, the skin serves as an adhesive not only in forming the longitudinal seam of the sleeve,

but also in bringing about adherence of the sleeve to the walls of the carton where that is desired. The modes of manufacture hereinafter described normally result in adhesion of the sleeve to the carton walls and in composite knocked-down structures, it is advantageous to have suflicient adhesion to maintain the association through the expected strains of shipment, and handling, filling, closing and the like. But general adherence has yet another advantage. Under conditions of Nevertheless, adhesion of the sleeve as such and the carton walls may be dispensed with, and is not a limitation on this invention unless expressed in the appended claims. Gas-tightness is not dependent either upon exact and complete surface conformity of the sleeve to the carton walls or upon adhesion of the sleeve to the carton walls.

Third, the skin may, and frequently does, have a useful effect in augmenting the gas-tightness of the sleeve and of the package.

I am not confined to a thermoplastic material as the substance of the skin. Any coating adhesive capable of forming a skin of the required characteristics may be used. For example, natural or synthetic rubbers or resins, or latices, emulsions or dispersions of these substances may be utilized; and if these are not reactable, they may be applied to the web just prior to its application to the carton. Thus, they may be caused to adhere the sleeve to the carton, and under some circumstances to serve as the adhesive for the longitudinal seam of the sleeve.

As a skin forming material I prefer to use thermoplastic substances. These may be applied to the web as a hot melt with advantage in the formation of dependably imperforate films. They permit both the formation of a longitudinal seam in the sleeve and the adhesion of the sleeve to the carton without additional adhesive and merely by heat-reactivation of the thermoplastic. Many of them present a. cost advantage.

The thermoplastic substance should have adequate film forming characteristics and should preferably be moisture-resistant and gas-tight in integral and imperforate layers. It should be cohesive at all of the temperatures which the packages may be expected to encounter; but it should be flexible and not brittle at such temperatures. It should bond well with the web and with paperboard.

v following:

parts of a mixture of 25 parts polybuteneof medium molecular weight (80,000 to 100,000) and 75 parts paraflin. A material of this character is commerciallyavailable under the trade name Tervan.

10 parts microcrystalline wax having a melting point around F. A material of this character is commercially available under the trade name Non-Pareil.

All parts in this typical formula are by weight.

The chosen web, for example glassine, is coated with the skin forming substance in any suitable fashion, as by being passed continuously over and in contact with a roll turning in a pan of the molten thermoplastic. The coated web may then be drawn over a heated smoothing bar which, contacting the coating, acts to unify it as to continuity and thickness. Both sides of the web may be coated, if desired; but this is not necessary and is not ordinarily practiced by me. The thermoplastic coating chills rapidly so that it is possible to rewind the coated web without encountering sticking or blocking. I slit the coated web into widths appropriate to the dimensions of particular carton orders. At this time or later, the web may be cut apart into sheets of required size.

As has been indicated, there are several ways in which a sheet formed as herein described may be applied in making up the package. The way preferred by me, since mechanisms for the purpose can be made simply, involves the application of the sheet to the folded, knocked-down carton after tubing. When this is done, the sheet is applied to the tubed structure, wrapped thereabout and closed with an independent lapped seam to form a sleeve. The sheet will adhere to the carton walls under the application of gentle heat, the skin of thermoplastic adhesive being, of course, located between the carton and the web. The seam in the sheet is preferably made by heat, lapped portions of the sheet being pressed together. Thus, a gas-tight sleeve is formed over the entire body portion of the carton. Yet the resultant structure is a collapsed or knockeddown, treated paperboard carton which may be handled, filled and closed as such.

In Figure 12 I have illustrated diagrammatically a mechanism which I may employ for forming sleeves about the collapsed bodies of tubular cartons. An elevated platform I! is provided with side and end guides l8 and I3 for positioning a sheet 2|] positioned on the platform with its skin or thermoplastic-coated side uppermost. The sheet may be placed in position by hand or by conveying means, not shown. Above the platform I provide a hopper 2| for holding a series 22 of tubular cartons in knocked-down form. A notched, pusher-type feeder 23 is provided in connection with the hopper and is driven in a vertically reciprocating fashion so as to move a tubular carton downwardly. As the carton engaged by the feeder 23 is so moved, a resilient means 24 retains the remainder of the cartons in the hopper.

The platform I! is divided so as to present an opening below the point of delivery of the cartons; and below this opening I mount a pair of pinch rolls 25 and 26, positioned to receive the carton and the sheet. The action of sending the carton and the sheet downwardly through these pinch rolls results in wrapping the sheet about the carton, as indicated at 21 in the samefigure. The pinch rolls 25 and 26 are preferably heated as by electrical heating elements so as to reactivate the thermoplastic coating on the sheet to the extent of causing the sheet to adhere slightly to the carton walls about which it is being wrapped.

The pinch rolls will preferably have about the same length as the carton body walls. Even in instances where the sheet and the sleeve formed from it are to cover the flaps of the carton, it is not desired that the sheet adhere to the flaps themselves.

As the carton and sheet are delivered to the position 21 by the pinch rolls, they come to rest on a lower abutment 23 and against a means 23 now occupying a vertical position, but pivoted on the frame of the machine, as at 33.

By suitable timed mechanism, the member 23 is swung downwardly to the position shown in dotted lines, carrying the carton and sheet also to a position shown in dotted lines, and delivering them to a conveyor or moving means II. A guide or deflector 32 is so located with respect to the path of swinging movement of the carton and sheet as to engage the projecting end 33 of the sheet and bend it upwardly, as indicated in dotted lines.

The conveyor 3| moves the carton and sheet forwardly into the pinch of a pair of rolls 3 and 35, the deflector 32 acting to fold the sheet end 33 back over and in lapping relationship to the other end of the sheet. The rolls 34 and", being electrically heated, iron down the lapping part 33 of the sheet and complete the formation of the sleeve by longitudinally seaming it, reactivating the thermoplastic skin, and pressing the parts together.

These rolls also may be about the same length as the carton body walls, even where the sleeve extends to cover the flaps, since a dependably gastight longitudinal seam is required in the sleeve only over the length of the carton body walls.

The completed assembly of carton and sleeve, indicated at 36, .is delivered by the inch rolls to a conveyor or other moving means 31 which carries it to stacking or other delivery means.

The assembled, collapsed product may be that illustrated in plan in Figure 13 and in section in Figure 14, in which figures the carton parts are marked with numerals corresponding to the indicia of Figure 1, and the sleeve is indicated at 33. The sleeve has a lapped, independent seam shown at 39.

Another way in which a similar structure may be attained is illustrated in Figures 3, 4 and 5, where the same carton is illustrated with like parts similarly numbered. A sheet 43 of the coated web is associated with the carton blank prior to folding and tubing. The sheet is so proportioned as to extend substantially beyond a body wall of the carton, as at 4|. Where the carton is to be tubed in the ordinary way with the glue flap 6 inside and lapped by the opposite body wall, the projection of the sheet 40 will be beyond the said opposite body wall as illustrated. If the carton is to be tubed with the glue flap outside, then the sheet 40 will project substantially beyond the glue flap. The lengthof the sheet will in any event be suflicient to permit the sheet to wrap entirely around the tubed carton blank, and to lap upon itself, beyond the glue seam of the carton, sufiiciently to provide an independent seam.

The sheet will be applied to the outside surface of the carton blank (the under surface in Figure 3) and may be ailixed to the carton blank by heat and pressure at one or more points or over the entire area of coverage. But the carton blank will have been scored prior to the application of the sheet, and the sheet itself will be unscored.

Figure 5 illustrates a portion of the carton blank and the projecting coated sheet. The paperboard carton blank is indicated at 42, the glassine or other web substance at 33, and the coating or skin of thermoplastic at 44.

with a suitable application of adhesive, as at 6a in Figures 3 and 4, the structure of these figures may be tubed by the usual machine and method. The adhesive to may be any suitable substance capable of bonding the parts. The adhesive for uniting the paperboard parts does not require the quality of gas-tightness. The wrapper sheet laps itself and is sealed together in an independent seam (as at 45 in Figure 6) under heat and pressure by means of the thermoplastic skin 44.

Where the carton itself has printed surfaces, these may be visible through the wrapper because of the transparency or translucency of the web 43 and the thermoplastic skin 44, especially where the wrapper is pressed under heat against the folded carton or blank so as to bring about surface conformity. However, it is within the scope of my invention to print the web 43 instead of or in addition to the paperboard carton blanks. This will be resorted to where the web 43 is not suiflciently translucent or where the paperboard material of the carton is not of such character as to take printing with the desired effect.

Figure '7 shows an erected carton composite, such as one made by the procedure outlined in connection with Figures 3, 4 and 5, in condition for closure at one end, filling, and closure at the other. Figure 8 shows the longitudinal seam in cross-section. In this structure the web 43 covers the carton glue flap 6 and is joined by adhesive 46 to the overlying wall I. This implies that the web 43 will be firmly adhered to the glue flap 6 by the film or skin 44. The sheet comprising the web and skin will, however, be lapped upon themselves, as at 45, in a separate seam, tightly sealed by means of the thermoplastic skin 44.

The filling and closure may be accomplished in ways, and by means, known in the art. A filled and closed package is illustrated in Figure 9. It has a gas-tight body portion but is pervious to gas at its ends. It is rendered completely gastight by dipping its ends in a molten thermoplastic substance so as to form over the ends and portions of the body walls cap- like films 41 and 48. This thermoplastic substance may be the same as that employed for the skin 44 but it may with advantage be a composition of harder, tougher character, capable of forming both thinner and more durable skins. It will preferably be a material having high adhesion to paperboard, to the web 40, and to the substance of skin 44, with which it is preferably compatible. It should remain pliable and non-brittle at all temperatures to which the package is to be subjected in commercial use.

Especially where the material of the adhesive is of waxy and resinous character, as will be set forth hereinafter, I prefer to use a waxy and resinous (and hence compatible) material for end d pping.

Again, without limitation of the generic aspects hi this invention, I give as a typical formula, which I have found very satisfactory for the purpose, the following:

Also, I may add parts of a medium microcrystalline wax having a melting point around 165 F.

All parts are by weight. This composition is nearly colorless, has strong film-forming characteristics, forms thin but tough and gas-tight films and bonds well with all materials and parts heretofore described.

The dipping may be done by hand or by any suitable apparatus. It will be. noted that the cap- like films 41 and 48 form cover portions for carton parts not previously covered by the sleeve, and are firmly bonded thereto. These cap-like closures overlap the ends of the sleeve and are firmly bonded to these ends. Because the sleeve does not cover the whole of the carton, but presents edges preferably near the ends of the body walls of the carton, the material forming the cap- like films 41 and 48 is able to bond with the skin 44 of thermoplastic or other material forming part of the sleeve. This insures complete gastightness. The end caps or closures serve additionally to fix the sleeve in place on the carton.

The cap- like closures 41 and 48, while strong, are in practice quite thin and do not detract from the appearance of the package. They may be made to contribute to appearance or distinctiveness by adding coloring materials to the composition from which they are formed. End dipping, it will also be understood, does not result in subjecting the whole carton or its contents to heat, as would an over-all immersion; and gives rise to no problem connected with internal expansion of atmosphere in the sealed package.

The order of the steps heretofore outlined may be varied. The carton may be closed at one end and then dipped'on that end prior to filling, closure, and dipping on the other.

While I prefer to make up in the order listed, composite, knocked-down structures, such as illustrated in Figures '7 and 13, it is possible, as hereinabove indicated, for the packager to erect, fill and close tubular paperboard cartons as such, afterward applying to them the treatment and elements making up my gas-tight structure. As indicated in Figure 11, the product may be completely packaged in the closed carton 49. Thereafter, the sheet 50 will be tightly wrapped peripherally about the carton with its ends in lapping relationship, whereupon the end portions of the sheet may be sealed in a longitudinal seam by the application of heat and pressure if the skin on the web is a reactivable thermoplastic. Otherwise, additional adhesive of a gas-tight nature may be employed in this and other forms of my invention for the longitudinal seaming of the sleeve. The operations may be performed by hand or by machine and they may produce a structure like that shown in Figure 9. Such a structure may then be end dipped as previously described, forming the end closure caps 41 and 48 and a structure such as that illustrated in Figure 10.

It may be noted that, especially where a sheet is to be applied to an erected, filled, and closed carton so as to form a sleeve, there is no limitation in my invention as to the particular periphery of the carton surrounded by the sleeve, and the sleeve may be so associated with the carton as to cover the closure flaps thereof. In this event, the cap- like closures 41 and 48 will cover and be bonded with remaining body wall portions of the cartons.

Yet again, it is possible under some circumstances to preform the sleeves and then associate them with cartons in either knocked-down or erected and closed form, by slipping the sleeve over the carton.

As has been indicated, a sleeve long enough to cover the body walls and the end flaps of a carton may be associated with either the carton blank or with a tubed, knocked-down carton. The modes of accomplishing this may be any of those described hereinabove in connection with Figures 1 to 8 and 12 to 14 inclusive, the only difierence being the use of a sheet of greater dimension in the direction of the length of the carton.

A collapsed carton 54 in association with such a sleeve 55 is shown in Figure 19. The sleeve, as before, will have its own, independent, longitudinal seam of a length at least approximately equal to the length of the body walls of the carton; and while the sleeve will preferably be adhered to the body walls of the carton, it will be preferably be unadhered to the carton flaps.

Such a carton and sleeve may be squared up or erected as shown in Figure 20. The carton flaps can then be interfolded, which will usually be done by hand because of the extending sleeve. The flaps may be adhesively secured or not, as desired. When the carton flaps have been folded down into position as shown in Figure 21, the sleeve will be folded across the end of the carton. This may readily be done by mechanism. The first operations involve folding the sleeve, inwardly from opposite walls (usually the narrower walls if the carton is other than square), as shown in Figure 22 at 56 and 51. Since the sleeve is coated within with a skin of thermoplastic substance, the use of heated pressure members, which may be the folding elements, will cause the portions 56 and 51 to adhere to the uppermost of the end closure flaps. This folding operation leaves upstanding ears 58 and 59 which will subsequently be folded inwardly, as shown in Figures 23 and 24. In the course of this folding operation, the ears may themselves be heated and pressed so that the sleeve walls adhere to themselves in the ears. Since the skin of thermoplastic substance is located on the inner surface of the sleeve however, a means may be required to hold the ears in folded position during a subsequent dipping operation. A cage may be employed for dipping which has a spring finger or the like to retain the ears; but it is possible and usually feasible to hold the ears in folded position by means of a spot of adhesive substance indicated at 60. This may be a thermoplastic substance or not as desired; but if it is thermoplastic, it is well to use a substance of higher softening point than that of the material used subsequently for forming the end caps, so that the ears will not be released during the end dipping.

When the carton flaps have been interfolded on-one end and the sleeve folded as described, the carton may be up-ended, filled through the opposite end, and closed in a similar fashion, whereupon it will be ready for end dipping. The result of the end dipping is the formation of caplike end closures 6i and 62 illustrated in Figure 25 and similar to the end closures which have been described in connection with Figure 10, excepting that these closures are bonded at the ends of the carton to the folded portions of the sleeve rather than to the carton flaps themselves. I have, however, found that excellent gas-tight packages may be formed in this fashion which have adequate mechanical strength where the sleeve is adhered to the body walls of the carton and where, preferably, the first infolded portions of ends of the sleeve are adhered to the carton flaps with the sleeve ears pressed and heated.

A structure such as shown in Figure 25 will be formed by applying a sheet to form a sleeve about a plain carton which has already been filled and closed. The operations are similar to those described in connection with Figure 11, to which are added the sleeve folding operations described in connection with Figures 21 to 24. In applying the sheet to form the sleeve, care is taken both to cause the sheet to adhere to the carton walls and to form a tight, longitudinal seam in the sleeve throughout at least the length of the carton walls. A gas-tight, longitudinal seam is readily formed in this way, and the end closure caps 6| and 62 form gas-tight closures at the ends of the package, whereas I have not found it possible to secure a gas-tight enclosure for a carton by merely wrapping it in a sheet to form a sleeve and by folding and adhesively securing the sleeve ends, in spite of the skin forming part of the sleeve, and in spite of additional adhesive employed or added during the folding of the sleeve.

By means and procedures hereinabove set forth, I produce gas-tight packages which are effective in preventing gaseous exchange between the atmosphere of the outside package and the surrounding atmosphere. For many uses a special atmosphere other than air is required in the packages. Such an atmosphere may be supplied in various ways. With heavier-than-alr gases, by way of example, it is quite feasible to erect and close the cartons on one end, flush them with the desired gas, introduce their contents along with additional quantities of the gas in which the contents are submerged, and then close and seal the cartons, retaining the interior gas so introduced. In other instances, it will be preferred to effect a gas exchange after a completely gas-tight package has been made. In this event the provision of the means, illustrated at is and hereinabove described, find utility. It will be noted, as in Figure 15, that the sleeve 5| covers the perforation or the flap-like means I! but as in Figure 16 the sleeve may be readily punctured by any suitable instrument. Cartons punctured in this fashion may be introduced into a closed chamber which is first exhausted, producing expulsion of the air in the containers through these perforations, and afterwards filled with the desired gas which then, to a large extent, takes the place of the atmosphere originally in the cartons. Such a procedure is described in my copending application Serial No. 557,984, filed October 10, 1944, and entitled Method of making gas-filled flexible containers. In another copending application, Serial No. 553,374, filed September 9, 1944, and entitled Method of gassing filled packages, .I have disclosed methods of effecting gas exchange in otherwise sealed containers by flushing them with gas through a hollow needle of the tube entering the carton and delivering gas within it at a point spaced as far as possible within the confines of the carton from an outlet for the atmosphere which must also be provided.

In Figure 16 I have shown a needle-like means 52 puncturing the sleeve and entering the container. The process may be carried on by providing two openings in the carton remote from each other, introducing gas by means passing through one of the openings and permitting atmosphere to escape through the other of the openings, which also may have been made by a needle or the like furnishing a hollow exit path. Or again, a single elongated needle with an enlarged and grooved upper end may be thrust into a carton in such a way that its point or outlet is 13 located remote from the perforation through which the needle entered the carton, the interior atmosphere of the carton escaping through the same carton perforation in the grooves in the enlarged upper end of the needle.

A carton gassed by these or other procedures requiring the provision of holes or openings may then readily be rescaled so as to retain the introduced gas. In Figure 17 I have shown the puncture in the sleeve closed by a patch of gastight material 52 which, in this instance, may comprise a web and a skin of thermoplastic similar to those set forth above for the sleeve itself. The patch will be applied under pressure with the thermoplastic adhesive reactivated by heat so as to eifect a seal. A seal may also be eflected in the sleeve 5|, as shown in Figure 18, by depositing over the opening a quantity of thermoplastic sealing substance indicated at 53. The substance will be applied in softened condition. It may be the same substance as that of the skin, but in any event, will preferably be compatible with the skin substance. It not only will be bonded to the web of the sleeve, but also, penetrating the perforation, will preferably be bonded to the skin on the under side of the web.

Modifications may be made in my invention without departing from the spirit of it. Having thus described my invention in certain exemplary embodiments, what I claim as new and desire to secure by Letters Patent is:

1. A moisture, vapor and gas-tight package formed of flexible materials and comprising as elements a closed paperboard carton having side and end walls, a preformed gas-tight sleeve of flexible material secured to the blank formin said carton and surrounding peripherally the side walls of said carton and closed by an independent gas-tight seam, and spaced cap-like closure elements overlying the end walls of said carton and overlapping the ends only of said sleeve and forming a moisture, vapor, and gas-tight seal therewith, and comprising each an imperforate skin of flexible gas-proof composition bonded in a gastight manner peripherally of said walls to said sleeve, said sleeve sewing to bridge the space between said spaced closure elements, and forming therewith a moisture, vapor, and gas-tight enclosure for said paperboard carton and its contents.

2. A moisture, vapor, and gas-tight package formed of flexible materials and comprising as elements a closed paperboard carton having side and end walls, a preformed sleeve surrounding peripherally the side walls of said carton and closed by an independent gas-tight seam, said sleeve comprising a skin of flexible gas-proof composition and an overlying protective web secured to the walls of said carton, and spaced closure elements overlying the end walls of said carton and overlapping the ends only of said sleeve and forming a moisture, vapor and gastight seal therewith and comprising each an imperforate skin of flexible gas-proof composition bonded in a gas-tight manner peripherally of said walls to said sleeve, said sleeve serving to bridge the space between said spaced closure elements and forming therewith a moisture, vapor, and gas-tight enclosure for said paperboard carton and its contents.

3. The structure claimed in claim 2 in which said web is of translucent substance and is adhered by said skin to said peripheral walls of said carton.

4. A process of producing a moisture, vapor,

and gas-tight package which comprises providing a paperboard carton having end closure flaps, forming on the exterior surface of said carton an overlying gas-tight covering of flexible material covering a series of walls thereof and lapping on itself with a gas-tight, independent seam of said lapped material to provide the carton with a preformed peripheral moisture, vapor and gastight sleeve on its exterior, folding said closure flaps to close the'ends of said tube and imposing upon the end walls of said carton spaced closure elements comprising each an imperforate skin of flexible gas-proof composition, and bonding said closure elements in a. gas-tight manner to said sleeve peripherally of said end walls, whereby said sleeve bridges the gap between said spaced closure elements and coacts to form a moisture, vapor, and gas-tight covering for said paperboard carton.

5. A process of producing a moisture, vapor. and gas-tight package which comprises providing a paperboard carton having end closure flaps, forming on the exterior surface of said carton an overlying covering of flexible material, said covering comprising a skin of flexible gas-proof composition and a protective web, said covering extending over a series of walls of said blank and lapping on itself with a gas-tight independent seam of said lapped material to provide the carton with a peripheral moisture, vapor and gastlght sleeve on its exterior, folding said closure flaps to close the ends of said tube and imposing upon the end walls of said carton spaced closure elements comprising each an imperforate skin of flexible gas-proof composition, and bonding said closure elements in a gas-tight manner to said sleeve peripherally of said end walls, whereby said sleeve bridges the gap between said spaced closure elements and coacts therewith to form a moisture, vapor and gas-tight covering for said paperboard carton.

6. The process claimed in claim 5 in which said closure elements are formed by imposing said gas-proof composition over said remaining walls and against adjacent portions of the sleeve peripherally surrounding the first mentioned walls whereby to form cap-like closure elements.

7. The process claimed in claim 5 including the step of terminating said sleeve substantially at the ends of the first mentioned walls of the carton.

8. The process claimed in claim 5 including the step of causing end portions of said sleeve to project beyond the ends of the first mentioned walls and folding said projecting portions against said remaining walls.

9. The process claimed in claim 5 including employing as said web a translucent material and adhering it by means of said skin to said first mentioned walls substantially throughout their areas.

10. The process of claim 5 in which said closure elements are formed by dipping portions only of the package including said remaining walls in a bath of thermosplastic gas-proof composition.

11. A process of forming a moisture, vapor and as-tight package which comprises providing a paperboard carton having a series of body walls in articulation and closure means, and wrapping said carton so as to form a sleeve covering contig-uous peripheral body walls in a gas-tight manner, said sleeve comprising a skin of flexible gas-proof composition and a protective web, and

closing said sleeve by a gas-tight independent seam, afterward imposing upon the remaining walls of said carton spaced closure elements comprising each an impertorate skin of flexible gas-proof composition, and bonding said closure elements in a gas-tight manner to said sleeve at end portions of said peripheral walls, whereby said sleeve bridges the gap between said spaced closure elements and coacts therewith to form a moisture, vapor and gas-tight covering for said paperboard carton.

12. The process of claim 11 wherein said sleeve extends beyond said peripheral walls, the extending portion being folded against said remaining walls, and wherein said closure elements are formed over and completely cover the so- !olded portions 01' said sleeve.

SAMUEL BERGS'I'EIlI.

18 REFERENCES crmn The following references are oi record in the file of this patent:

UNITED STATES PATENTS Number Name Date 550,870 Cooke Dec. 3, 1895 925,913 Jenkins June 22, 1909 1,692,822 Ecksfein Nov. 27, 1928 1,870,977 Wilson Aug. 9, 1932 1,969,009 Hutt et al. Aug. 7, 1934 2,008,167 Bergstein July 16, 1935 2,048,123 Howard July 21, 1936 2,139,626 Sidebotham Dec. 8, 1938 2,201,416 Wagner May 21, 1940 2,259,822 Kienlen Oct. 21, 1941 2,333,330 Moore Nov. 2, 1943 2,380,427 Gllfillan July 31, 1945

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