US2776608A

US2776608A - Method of making a multi-layered container

Info

Publication number: US2776608A
Application number: US279618A
Authority: US
Inventors: Paul E Fischer; Robert S Hedin; Charles H Swanson; Henry E Wissman
Original assignee: General Mills Inc
Current assignee: General Mills Inc
Priority date: 1952-03-31
Filing date: 1952-03-31
Publication date: 1957-01-08
Anticipated expiration: 1974-01-08

Description

1957 P. E. FISCHER ET AL 2,776,608

METHOD OF MAKING A MULTI- LAYERED CONTAINER 4 Sheefs-Sheet 1 Filed March 31. 1952 (I LL] 0. E

iii! a I i I Q SR N m m T EN sHAs V .W& W SS EMHE ES MBEM A O L N PRR A H 0 Jan. 8, 1957 P. E. FISCHER ET AL 2,776,508

METHOD OF MAKING A MULTI-LAYERED CONTAINER 4 Sheets-Sheet 2 Filed March 31, 1952 FIG9 l/V VENTORS R N EM%A HENM CHAS .wm r w EMH ES MBEM NAOLYN PRR H Bylaw ATTORNEY Jan. 8, 1957 P. E. FISCHER ET AL 2,776,603

METHOD OF MAKING A MULTI-LAYEIRED CONTAINER Filed March 31, 1952 4 Sheets-Sheet 3 "III,"

INVENTORS PAUL E. FISCHER ROBERT S. HEDIN CHARLES H. SWANSON HENRY E. WISSMAN ATTORNEY 1957 P. E. FISCHER ET AL 2,776,608

METHOD OF MAKING A MULTI-LAYERED CONTAINER 4 Sheets-Sheet 4 Filed March 31, 1952 FIG.28

INVENTORS PAUL E. FISCHER ROBERT S. HEDIN CHARLES H. SWANSON HENRY E. WISSMAN gywl gMxrraR/vn United States Patent O WTHOD OF MAKING A MULTI-LAYERED CONTAINER Paul E. Fischer, Minneapolis, Robert S. Hedin, St. Paul,

Charles H. Swanson, Minneapolis, and Henry E. Wissman, St. Paul, Minn., assignors to General Mills, lno,

' a corporation of Delaware Application March 31, 1952, Serial No. 279,618

Claims. (Cl. 93--36.8)

This invention relates to improvements in multi-layered containers and blanks and the methods for making the same.

There are many advantages known to the art in a con tainer formed of a plurality of layers of material as compared with a container formed of a single layer. These advantages lie principally in the enhanced properties of the container but usually are accompanied by the disadvantage that the container is more difficult to construct.

In a container which is constructed for use with foodstufis and other erishables, it is generally desirable to achieve a high degree of moisture-proofness. In addition, the container should be reasonably strong. An ideal container from many standpoints is the tin can, but this is not always practical as it is relatively expensive, is limited in the shape which can be economically obtained, and requires certain machinery for its manufacture. A container which is made of a plurality of layers which include metallic foil can approach the moisture-proof properties of a rigid metal can and yet be manufactured at a small fraction of the cost. Metal foil, however, is not practical for use alone as it lacks rigidity and, when used in very light weights, may be marked with minute holes which admit passage of air and moisture. If the metallic foil is combined with layers of paper which add rigidity and which are relatively inexpensive, and is also com bined with layers of adhesive materials, such as a thermoplastic, which serve to block the minute holes in the foil and secure the paper and foil together, an improved container will result. In addition, if several layers of foil are used so that the container has foil on the inside facing the contents of the package and foil on the outside to protect the container from atmospheric elements, a very suitable package will be formed. The foil on the outside also enhances a commercial package in that it presents a pleasing surface which is attractive to the customer and is conducive to impulse buying.

When forming a package of a plurality of layers, such as above described, care must be taken so that the layers will remain properly oriented with respect to each other in order to form a neat appearing package and one which will not leak air and moisture due to one of the layers being out of position. Maintaining the various layers in their proper positions is especially difficult with the use of metallc foils as they are notoriously soft and fragile and are easily scuffed, bent or torn. Difficulty is especially encountered when folding a package from a blank formed of laminated layers because of the tendency of the inner blank to wrinkle and the outer blank to stretch when the material is bent to form a corner. The present invention provides a container and blank and method of making the container and blank which avoid the difliculties inherent when working with a plurality of layers of material and material which is soft. Although the invention provides a great many advantages for handling material such as metallic foil laminated in layers by a thermoplastic adhesive, materials of other types may be used, obtaining many of the advantages of the present invention.

Accordingly, an object of the present invention is to provide a greatly improved method of forming a container from a plurality of layers of material wherein the layers of material are permitted to freely shift with respect to each other and the tendency of the inner layer to wrinkle and the outer layer to stretch when folded will be completely avoided.

Another object of the invention is to provide an improved multi-layered blank and method of making the blank which will permit the rapid forming of a container from the blank without disturbing or altering the relative positions of the layers of material and yet permitting the materials to slide with relation to one another.

Another object of the invention is to provide a method of forming a multi-layered container laminated with thermoplastic adhesive in which the container is completely formed with the unlaminated layers and maintained in their proper relative positions and the attaching of the layers is performed as a final step after the folding of the container.

A further object of the invention is to form a multilayered blank and to fold the container therefrom in which the layers are not laminated to each other, but which is capable of withstanding handling without displacing the positions of the layers and which will enable lamination of the container layers at some later time subsequent to the folding of the complete container.

Other objects and advantages will become apparent in the following specification taken in connection with the drawings in which Figure l is a schematic view shown in perspective illustrating the method of preparing the multiple layered blank;

Fig. 2 is a perspective view of the first layer of the blank which will form the outer layer of the container;

Fig. 3 is a perspective view of the outer layer with an additional layer attached which will form the intermediate layer of the container;

Fig. 4 is a perspective view of the outer and intermediate layers with a third or inner layer attached which will form the inner lining of the blank, facing the contents thereof;

Fig. 5 is a sectional view taken along line 5-5 of Fig. 4 illustrating the preferred construction of the inner layer of the blank;

Fig. 6 is a sectional view taken along line 6-6 of Fig. 3 illustrating the preferred construction of the intermediate layer of the blank;

i Fig. 7 is a sectional view taken along line 77 of Fig. 2 illustrating the preferred construction of the outer layer of the blank;

Fig. 8 is a plan view of the multi-layered blank positioned on a device for forming the blank into the container;

I Fig. 9 is a front elevation of the blank positioned on the forming device of Fig. 8;

Fig. 10 is a front elevation illustrating the blank partially folded;

Fig. 11 is a front elevation showing the mechanisms of Figs. 3 through 10 with the edge of the container blank partially folded down to begin folding the final side wall of the container;

Fig. 12 is a front elevation of the mechanism of Figs. 8 through 11 illustrating the folding of the edge of the blank shown partially folded in Fig. 11;

Fig. 13 is an enlarged front elevation illustrating a container as folded into an open-ended four-sided tube;

Fig. 14 is a'perspective view of the container as formed into a tube with a portion of the side wall broken away to show the location of the bonds which secure the layers of material together;

Fig. is vertical sectional view illustrating the beginning of the folding of the end 'fiaps of the container;

16 is a perspective view of the container with the fol-z. ng of the first end flap having been accomplished;

Fig. 17 is a vertical sectional view illustrating the folding of the second end fiap over the container end;

Fig. 13 is a plan view illustrating the flattening of the side ears of the container;

Fig. 19is a perspective view illustrating the-container after the action of the members of Fig. 18;

Fig. 20 is a plan view illustrating the folding of the ears over the container end;

Fig. 21 is a side elevation with the container in vertical section showing the folding of .the cover flap over the other folded flaps of the container end;

Fig. 22 is a perspective view showing the completely folded container;

Fig. 23 is a sectional view taken along lines 23-23 of Fig. 21 and being enlarged to show the location of the bonds between the layers of container material;

Fig. 24 is a vertical sectional view illustrating the insertion of the container into the moulding box prior to the attachment of the layers of the container;

Fig. 25 is a vertical section illustrating the application of heat to weld the walls of the container;

Fig. 26 is a plan view showing the withdrawal of the container from the welding mechanism;

Fig. 27 is a perspective view showing the finished container; and

Fig. 28 is a sectional view taken along line 2328 of Fig. 27, showing the location of the bonds between the layers of material after'the softening of the thermoplastic adhesive between layers and the welding of the layers together.

Referring to Fig. l, the method of forming and attaching to each other .the various layers which make up the completed blank are shown. The individual blanks which form the layers for the completed multi-layered blank are each severed from the web of material and assembled together by being individually placed on the next outer blank. The intermediate blank, for example, is carefully laid on the outer blank and attached thereto over only a limited area of theblanks. The inner or top blank is then laid on the two joined blanks and attached to the intermediate blank over only a limited area.

The areas in which the'bonds which attach the blanks to each other lie, are restricted to being within oneside wall 'of the container. Thus, when the remaining side walls of the container are folded, the layers which form the blanks will be permitted to slide with respect to each other, thereby avoiding any wrinkles or any tensions between the blanks. In the illustrated embodiment, thermoplastic adhesive is used to join the blanks to each other. It is to be understood, however, that other adhesives could be used, while thermoplastic is preferred, because of the simplicity with which the entire container can be later welded by softening the adhesive by penetrating the walls ofthe formed container with heat.

Fig. 7 illustrates a construction which may be used for the outer layer of material. The lowermost layer of paper is metallic foil which is faced with a layer of thermoplastic, such as wax. The 'wax serves to seal the pores which may be present in the foil and will when heated, penetrate the paper which is placed over the wax. The paper which will be penetrated by the wax serves as a binder and also serves as a non-adhering separator enabling storing of the material on rolls without the layers sticking together.

Fig. 6 illustrates a construction which may be used for the intermediate layer of the material. The layer shown is formed of paper and coated on each side with thermoplastic, such as wax. The wax serves as a binding adhesive, penetrating the paper when heated and has a certain amount of rigidity which makes it serve as a stiffener for the walls of the container.

Fig. 5 illustrates a construction which may be used for the inner layer of material for the composite blank. The material is formed with a layer of metallic foil on the upper side so as to face the contents of the container and has a layer of thermoplastic such as wax, coated thereon to close any pores which may be present. A layer of paper is placed over the wax which will serve as a binder when the waxbecomes'heated and penetrates the paper, and which also serves as a separating non-adhering layer permitting the paper to be stored on rolls.

Referring now to Fig. 1, mechanism which may be used to form the blank is shown. The material from which blanks for the outer layer will be formed is wound on a roll 30 rotatablycarried'on-a shaft 32 and may be drawn therefrom in web form 34 over a decurler mechanism 36 which removes the curl that has been acquired in the material from having been stored on the roll. The material 34 passes over tensioning roller flfiand upwardly past a steadying plate 40, opposite which is mounted an electric eye 4-2 which controls the rate of feed of the material. Markings 44 appear on the outer face of the material spaced a distance equal to the length of the blank. The electric eye records the passing of these marks and controls a feeding mechanism, not

shown, to regulate the feed of the material.

The blank next passes up through an edge decurler 46 and over a roller '43, being led horizontally and down over a roller '50 and doubled back to pass over a roller 52 andhence down over a drive roller 54 against which the material is clamped by roller 56. The webbing material then passes down over a roller '58 above a smoothing plate 60 and over a roller 62 which draws the material forward. The material is intermittently clamped against this roller 62 by roller 64 to cause the material to be intermittently driven. When the roller 64 is not clamping the material against the drawing roller 62, the material is held stationary by a brake which consists of alower plate 66 and an-upper clamp 63 which is raised and lowered to cause the braking action.

The drive roller '54 has continuous motion so. that when the material is not drawn forward by the lower rolls, a loop'70 is formed in the material. The roller 62 'has a much higher peripheral speed than the upper drive rollers and so removes the loop from the material when it operates.

During the time the material is not being drawn forward and is held by the brake, a blank'32 is severed from the 'end of the web by the knife 84. Additional slitting knives -86 on one side of the blank and 88 on the. other side of the blank form slits in the blank edge to form cover flaps 90 for the container ends, as shown 'on the blank 82 of Fig. 2. The knives 84, 86 and 88 are carried on a vertically reciprocating supporting block 9t driven by a crank 96 connected to a pin 98 on the block which slides in vertical guides 1'00. After the knives cut a blank from the end of the web they are lifted free of the web and the brake member '63 is raised to release the web and the roller '64 is lowered to carry the web forward.

To draw the foremost portion of the web forward and prevent the drive roller 62 from doubling 0r wrinkling the free end of the web as -it pushes it forward, a pulling roller 102 is provided at the web end. This free end of the web is clamped against this forward pulling roller byrollers 104 which are intermittently raised and lowered against the :drive roller 102 by action of the block 94, through mechanism not shown. When the knives are lowered roller 104 is raised and when the knives are raised'roller .104 is lowered to pull the end of the web for-ward.

To draw the severed blank away from the knives, the blank is pressed between blank removing rollers 106 and 108. Roller 108l1as a high portion 110 which comes around to catch .the blank, forcing it against roller 106, just after the blank has been severed from the end of the awaeos web. After the high portion 110 has passed the roller 106, these rollers cease to engage and cease to drive the material.

The blank is then carried through the mechanism by a conveyor, not shown, but which follows the path indicated by the dotted lines 112.

The next step is to applyand attach the intermediate layer to the outer layer to form a two-layer blank. The material for the intermediate blank is fed from a roll 114 rotatably suspended on an axle 116. The webbing 118 may be drawn off the roll over rollers 12 and 122 and upwardly through a decurler mechanism 124 which removes the curl which the web acquired in being wound on the roll. The web may then be fed horizontally over rollers 126 and downwardly over roller 128. The web is then fed downwardly over roller 130 and reversing it passes betweendrive rollers 132 and 134 and beneath a cutter cylinder 136 which carries a knife 138 to sever blanks from the end of the web.

The intermediate blank 140 which is cut from the end of the webbing is carried downwardly and laid on an outer blank 142 by the attaching cylinder 144. The outer blank passes between the attaching cylinder and a lower pressure roll 146 to have the intermediate blank attached thereto. To secure the intermediate blank to the outer blank a narrow strip of thermoplastic adhesive running across the material is heated. When the heated thermoplastic adhesive contacts the lower strip, the two blanks are secured together. The thermoplastic adhesive may be heated by an electrically heated bar 148 fixed to extend axially along the surface of the attaching cylinder 144.

The outer blank 142 is shown in Fig. 3 having the intermediate blank 140 attached and the area in which the two blanks are attached is indicated by the markings 150. The

dotted lines

152 and 154 in Fig. 3 indicate the boundaries of a side wall of the container which will be formed from the blank. It is important that the area in which the two blanks are bound together be located within one side wall. This is because the container blank when folded will be bent about the

lines

152 and 154 to cause sliding between the two sheets. The bonds, lying within the one side wall which remains unbent, are not affected by the relative shifting of the sheets at the corners of the container.

With the two sheets joined, the inner sheet is next attached to form the three-layered blank. The inner layer is formed from a sheet cut from a web 156 drawn from a roll 153 which rotates on a shaft 160. The web passes upwardly over

rollers

162, 164 and 166 and over angled roller 168. The web passes downwardly over roller 170 and between

drive rollers

172 and 174, and thence beneath cylinder 176 which carries a cutting knife 178 to sever an end from the web to form the inner sheet 180. The inner sheet is positioned on the two attached sheets as they pass between the blank attaching drum 182 and the lower pressing roller 184. The inner sheet is attached to the intermediate sheet by a narrow strip of adhesive extending across the material, as indicated at 186 in Fig. 4. It is to be noted that this narrow strip also lies within the dotted

lines

152 and 154 which designate the'bounds of one side wall of the container.

The narrow strip of thermoplastic adhesive which secures the inner sheet to the intermediate sheet may be activated by a heated member, such as axially extending bar 188 in the surface of the attaching drum 182.

The intermediate blank 140 is of a narrower width than the outer blank 90 extending only to the height of the container asshown by

dotted lines

191 and 193 which indicate the planes of the top and bottom of the container. The blank then does not add thickness to the folds at the container end but gives it body strength and adds layers of thermoplastic and paper to the body.

The inner blank is narrower than the outer but extends over the top of the container and increases the number of seams on the top fold and hence increases the number of moisture barriers in the fold.

Thus, three sheets have been cut from separate webs of material and accurately positioned with respect to each other and attached. The attachment has been made along narrow areas extending across the material or in a direction parallelto the axis of the container which will be folded from the blanks. The blanks have been attached by thermoplastic adhesive, but it is to be understood that other adhesive or other forms of attachment may be utilized.

The blank which is illustrated in the drawings is formed of three sheets and it will be readily understood that the blank could be formed of only two sheets or more than three sheets can be used if desired. The intermediate sheet is attached to the outer sheet within the confines of one side panel of the container and the inner sheet is attached to the intermediate sheet within the confines of the same panel.

It will be recognized, however, that as long as each attachment is between only the two contacting sheets, the lines of attachment need not be restricted to being within the same panel, but may be in two adjoining panels. For example, the intermediate sheet could be attached to the outer sheet in the area bounded by lines 152 and 151 and the inner sheet could be attached to the intermediate sheet within the panel indicated between

lines

152 and 190. In that case, the first crease to make in the container should be along the line 152, so that the crease is adjacent a panel wherein the layers are attached. If, however, the method of forming the containers utilizes the mechanism shown in the drawings of Figs. 8 through 13 where one panel is clamped, it is preferred to have the attachment between the sheets located within the same panel of the container.

It is to be noted that since the line of attachment between the blanks runs parallel the side edges or the axis of the container, the slippage when the sheets are folded to tubular form will be equal from the top to the bottom of the container and thus the slippage will have no misaligning eifect on the container.

Referring now to Figs. 8 through 13, a method of folding the blank to form a container will be illustrated. The multi-layered blank 192 may be laid on a forming machine on

plates

194 and 196 against rear guides 198. The blank may be accurately positioned by

lateral guides

200 and 202 mounted on the

plates

196 and 194, as shown in Fig. 8.

The first step in folding the blank is to fold the two

sides

204 and 206, which are adjacent the panel of the blank which will form the side wall 208. It is to be noted that the panel representing the side wall 208 is the one in which the bonds connecting the sheets of paper to form the blank are located. To fold the side walls, a mandrel 210 descends, clamping the side wall 203 against a plate 212 which is urged upwardly by a spring 214. As the mandrel 210 descends, it folds the

side Walls

204 and 206 upwardly by carrying the blank down into the folding well formed by the

side members

216 and 218, as shown in Fig. 10. In some of the views the multi-layered blank is shown as a single layer to simplify the drawings,

When the three side walls have been formed, the final side wall is formed by folding the extending flap 220, which projects from the side wall 206, against the upper face of the mandrel 210. This may be done by first creasing the flap 220 along its line of attachment to the side wall 206. This is done by a creasing blade 222, and the folding is completed by the plate 194 traveling laterally across the top of the mandrel. The opposing flap 224 is then folded over flap 220 by the folding plate 196, as indicated in Fig. 13. This completes the container 226, folding it into tubular form, the container now having the shape shown in Fig. 14. The seam formed 7 along the upper side of the container is not sealedbut held in place by the plate.

As shown by the broken away section of Fig. 14, the areas which bond the sheets of the container blank together lie entirely within the lower side wall 208 of the container. The container blank hasbeen folded to form a tubular-shaped structure without additionally attaching the sheets forming the blanks. The broken away portion is shown sectioned as a single layer for simplicity but it must be recognized that there are three layers which are unjoined at this stage.

To complete the folding operation on the container, the bottom end projection beyond the mandrel is folded over the end of the mandrel. This may be accomplished by first folding in the lower end panel 228, as indicated" in Fig. by a pivotally movable folding shoe 230. The container is held in tubular form by folding plate 196 remaining over the top of the mandrel 210. The container is illustrated in Fig. 16 having the end panel 228 folded against the end of the mandrel and into the plane of the container end.

The opposing panel 232 is next folded against the end of the mandrel and over the end panel 228' by a pivotal'ly moving shoe 234. The cars 236 and 238' formed by this fold are flattened, such as by

shoes

240 and 242 pressing over against the rounded sides of the folding shoe 234. The container end is thus folded, as illustrated in Fig. 19. Shoe 234 may be heated such as by heating elements 244, so as to activate the thermoplastic adhesive on the under side of flap 232 and causes it to adhere to flap 228 and to activate the adhesive between the layers which form the ears.

The

triangular ears

236 and 238 are next folded against the end of the container. This may be accomplished by a pair of

folding blades

246 and 248. Blade 246 may be mounted on a pair of

pivotal arms

250 and 252 and plate 248 on a similar pair of

arms

254 and 256. The inner arms of each of the plate supports 252 and 254 are connected by segment gears 258 and 260. The

plates

246 and 248 thus mounted, are made to swing inwardly from the dotted line position to the full line position of Fig. 20 to fold the container cars from the dotted line to the full line position. The shoes may be actuated by pivotal'ly moving the arm 262 which is secured to the segment gear 258.

To complete the folding of the bottom of the con tainer, the cover flap 264 is folded over the folded ears and the folded panels, Fig. 21. This may be accomplished by moving a heated folding head 266 upwardly to draw the flap 264 over the ears. The head 266 is mounted on a support 268 which carries it upwardly to fold the cover flap and the

ear folding shoes

246 and 248 are slid upwardly off the end of the container to hold the ears in place until the flap can be folded over them. The head 266 is heated by elements 270 and thereby activates the thermoplastic coating on the flap surface to cause it to adhere over the end of the container. This sealing of the end serves as a means to tack the folded elements in position, rather than permanently secure them.

The finished container with the bottom flaps tacked and with the layers secured to each other along one side wall is illustrated in Fig. 22. The container thusformed is held in folded position but still leaves the layers of material free to shift with respect to each other if the container is expanded or pushed together.

In Fig. 23 the bonds 186 and 150' between the layers of material are shown. It will be noticed from this enlarged drawing that the inner sheet material 180, when folded to form the corner of the container, extend around a much smaller radius than either the outer layer 80 or the intermediate layer 140. When the sides of this material are folded upwardly to form the corners of the container, it will be'apparent that there must be a shifting between the layers to allow for this difference in radius of curvature. The same holds true when the container is folded to form other corners,

The container may be completed by mechanism such as shown in Figs. 24 through 26. The completion of the container requires the welding of the plurality of layers which comprise the blank to form a monolithic structure.

The container 226 is stripped from the mandrel 210 by a stripper plate 264 which is recessed in the end of the mandrel. The plate is carried outwardly on a rod 266 slidably mounted in the mandrel. The stripper plate 264 carries the container into a pocket 268 in a carrier 270 which is cradled on a supporting member 272. When the container is in the pocket of the carrier, the carrier pivots to vertical position in its cradled support and a heated mandrel 274 is inserted into the container. The mandrel is heated by elements 276 supplied with electricity by leads 278 and is expandable so that it presses the container tightly against the walls of the supporting pocket. Since the layers of material are unattached, as the mandrel expands the walls of the container are forced tightly into the corners of the supporting pocket and the layers of material slide with respect to each other so that no tensions or wrinkles are formed. With the container thus held, the heat penetrates its walls and the thermo plastic adhesive is softened to flow into the cracks and crevices and be absorbed by the paper which forms some of the layers of the blank.

When the thermoplastic is adequately softened, the expanding mandrel may be withdrawn and the container pulled from its pockets, such as by grippers shown in Fig. 26. These

grippers

280 and 282 have a roughened jaw 284- and a cooperating resilient jaw 286 which grasp the extending sides of the container and which then move away from the pocket to draw the container therefrom. The container tends to hold its formed position because of the adhesive character of the thermoplastic and because of the metallic foil of the container which has a tendency to remain 'as it is bent. The container is then permitted to cool to solidify the thermoplastic, The finished product is shown in Fig. 27.

An enlarged sectional view is shown in Fig. 28 illustrating how the thermoplastic adhesive now presents a complete binding layer spreading entirely between the sheets. The bonding thermoplastic, as indicated at 290, securely holds the layers together and forms a rigid monolithic container. The layers, which have been permitted to slide with respect to each other up to the time at which the container was completed, have no strain or stresses and are free to lend their entire strength toward the formation of a superior container.

Thus it will be seen that we have provided a container and container blank and method of making the same which are capable of yielding a superior container. The method is well adapted to high-speed mass production of manufacturing containers as the blank may be made up of any number of layers of sheets and yet be as easy to handle as the single sheet. Various numbers of sheets of different materials can be used, each lending their own peculiar quality and yet the finished product will have greater strength than a container formed of a single sheet of one type of material of equal thickness. The multiple sheets forming the container will lie evenly and will not be marred by wrinkles or tears and will not be marked by internal strains and stresses which detract from the strength and efficiency.

We have, in the drawings and specification, presented a detailed disclosure of the preferred embodiment of our invention, but it is to be understood that as the invention is susceptible of modifications, structural changes and various applications of use within the spirit and scope of the invention, we do not intend to limit the invention to the specific form disclosed but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by our invention.

We claim as our invention:

1. The method of making containers having a plurality of layers of material which comprises assembling a plurality of sheets of material, said material including a thermoplastic layer between the sheets extending throughout the entire area of the desired container body, initially applying heat to a limited area and thereby adhering the sheets to each other to form a composite blank, simultaneously folding all of the sheets of the blank into a tubular body portion in which the layers are super-' imposed and thereby creating an unsecured seam running along one side of the body portion, folding the elements at one end of the blank to close one end of the body portion, adhesively securing at least a portion of said end elements without securing said unsecured seam to retain the elements and container body portion in folded position while receiving further handling, and subsequently securing said side seam, and welding the sheets of material to each other by applying heat throughout the entire area of said body portion to form a smooth, strong, multiple-layered container.

2. The method of making containers having a plurality of layers of material, at least one of which includes a thermoplastic layer throughout the entire area of the desired container body, which comprises assembling a plurality of sheets of material, initially applying heat to a limited area and thereby adhering the sheets to each other to form a composite blank, the total area in which the sheets are initially adhered to each other entirely lying within one side wall of the container to be formed, simultaneously folding all of the sheets of the blank and thereby forming a tubular body portion in which the layers are superimposed, closing one end of the body by folding the end of the tubular body to form an end wall, adhesively securing at least a portion of said end wall to maintain it in folded position, and thereafter applying heat and pressure throughout the entire area of said body portion and thereby welding the superimposed layers smoothly to each other throughout said body portion.

3. The method of making containers having a plurality of layers of material which comprises assembling three sheets of material, said material including a thermoplastic layer between each pair of contacting sheets throughout the entire area of the desired container body, initially applying heat to a limited area and thereby adhering the sheets to each other to form a composite blank, the total area in which the sheets are initially adhered to each other lying entirely within one side wall of the container to be formed, simultaneously folding all of said plurality of sheets to form a tubular body portion in which the layers are superimposed, closing one end of the body by folding the end of the tubular body blank to form an end wall, adhesively securing at least a portion of said end wall to maintain it in folded position, the seam at the side of the container remaining unsealed, and subsequently welding the sheets of material to each other by applying heat throughout the entire area of said body portion to form a completed container.

4. The method of forming a container having a plurality of layers which comprises forming an outer layer with material extending beyond the length of the side walls to be folded over the end of the container, forming an inner layer with material extending beyond the ends of the side walls to be folded over the end of the container, forming an intermediate layer being coated with thermoplastic adhesive on both sides to face the inner and outer layers and being of a width equal to the height of the side walls, assembling the blanks and folding them into a container, restraining the outer surface of the container to hold it to the desired container size, and applying heat to the inner walls to actuate the thermoplastic and simultaneously forcing the walls outwardly to joint the layers to each other to form a container having attached layers.

5. The method of forming a container from a blank having a plurality of separate superimposed layers, the layers including a plurality of body wall areas adapted to be folded into a tubularbody portion with end closure portions and being coated with thermoplastic, which comprises initially adhering the layers by applying heat to a limited area located entirely within only one of said body Wall areas, clamping the blank between two faces over an area representing said one side wall of the container, folding two adjacent side walls of the container at right angles to said one side wall, folding the two edges of said side walls together to form the remaining side wall, mechanically holding the edges together to form a seam, folding the end closure portions of the blank to form a container end at right angles to the side Walls, thereafter applying heat to the layers to soften the thermoplastic coating and weld the layers forming the container walls while holding the container in the desired shape, and cooling the thermoplastic to form a completed multilayered welded container.

References Cited in the file of this patent UNITED STATES PATENTS 503,777 Sutton Aug. 22, 1893 550,870 Cooke Dec. 3, 1895 808,520 Duskell et al Dec. 26, 1905 1,762,702 Smith June 10, 1930 2,043,829 Grant et al June 9, 1936 2,432,053 Waters Dec. 2, 1947 2,506,057 Bergstein May 2, 1950