US3498527A - Paperboard container for liquids - Google Patents

Description

March 3, 1970 H. B. MOORS mL 3,498,527

PAPERBOARD coNTAiNER FOR LIQUIDs F IGLI,

2 Sheets-Sheetl 1- Filed sept. 28. 1967 March 3, 1970 H. B. Moons ETAL PAPERBOARD CONTAINER FOR LIQUIDS 2 Sheets-Shaml 2 Filed Sept. 28, 1967 FIGB.

FIGA.

N D T CG xA IN AN Tl G ST WM A 2 Lm D. 5 PC IMl PLASTIC COATING PAPERBOARD HEAT souRcE CoA-ren IIIIIIIIIlIl-Pll United States Patent O 3,498,527 PAPERBOARD CONTAINER FOR LIQUIDS Harold B. Moors, Richboro, William E. Schwenk, Norristown, William J. Crothers, Jr., Exton, and James N. Ademino, Ambler, Pa., assignors to International Paper gonllpany, New York, N.Y., a corporation of New or Continuation-in-part of application Ser. No. 454,935,

May 11, 1965. This application Sept. 28, 1967, Ser.

Int. Cl. B65d 5/72, 5/40 U.S. Cl. 229-48 8 Claims ABSTRACT OF THE DISCLOSURE Paperboard containers, and blanks for assembling such containers, in which the paperboard surface is coated and the portion of the uncoated edge, in a substantially continuous line at the bottom of the Iside seam and bottom seam, is impregnated with a thermoplastic material, such as wax, so that such impregnated edge is liquid repellent when exposed to the liquid contents of the assembled container and the method for making such containers by heating the edge of the container and contacting such heated edge with the impregnating material.

This application is a continuation-impart of U.S. application Ser. No. 454,935, filed May 11, 1965, now abandoned and relates to paperboard containers and methods for making such containers.

Paperboard containers are widely used for packaging a variety of liquid products, such as, milk, juices, Syrups, and the like, and are erected, or assembled, from banks cut from paperboard stock coated on one or both surfaces with a protective coating of thermoplastic material, `such as, wax, or polyethylene. Such blanks are embossed so that, when folded along the embossed lines in erecting or assembling the container, top and bottom closures and side walls are formed. Ordinarily, such containers are folded and side seamed, by machine, and the folded and seamed blank is shipped flat to the iiilling point. The at, 'seamed blank is opened up, the bottom of the blank is folded and sealed, the container is filled with the desired liquid, and the top of the container is then folded and sealed. All of this is usually done where the container is iilled and by machine.

There are many geometrical configurations in which the blank may be cut and embossed to form such a container and the instant invention is not concerned with any particular configuration. In all such configurations, however, the blank is cut from precoated paperboard `stock and, when cut, raw, or uncoated paperboard edges are left around the blank. When folded into the container, certain of these raw, uncoated, paperboard edges are exposed to, and in cnotact with, the liquid contents of the container.

The paperboard stock is relatively thin and the raw, or uncoated paperboard edge exposed to the liquid contents in the container is relatively narrow. It has been discovered, however, that during shipment of such paperboard containers with some liquids, for example, orange juice, vibration of the container and its liquid contents causes a slight, but substantially continuous, liexure in the side wall at the bottom of the container to seep or and that this vibration causes the liquid in the container wick into the raw, uncoated and exposed edge of the paperboard, weaken the structure of the container and cause leakage of the liquid.

One of the objects of this invention is to provide an improved paperboard container for liquids.

Patented Mar. 3, 1970 Another object is to provide a method for making such container.

A further object is to provide such a container, and method, in which the paperboard edge at the side and bottom of the seam is sealed against leakage.

Still a further object is to provide a blank from which such container can be erected, or fabricated, on machines presently in use.

These and other objects will be more apparent from the following description and the appended drawings in which:

FIGURE 1 is a plan view of a container blank in accordance with the instant invention;

FIGURE 2 is a perspective view Iof the bottom of a container assembled from the blank of FIGURE l showing the bottom closure, as the container is being assembled;

FIGURE 3 is an enlarged plan view, partly in section, of a fragment of the container of FIGURE l showing in enlarged detail the impregnation of the paperboard blank;

FIGURE 4 is an enlarged cross sectional view taken along lines 4-4 of FIGURE 3;

FIGURE 5 is a view, in side elevation, of a schematic illustration of the method of the instant invention, and

FIGURE 6 is a top plan view of the schematic illustration of FIGURE 5.

There are many geometrical shapes and sizes of coated paperboard container blanks of which the container blank illustrated, and hereinafter described, is but one. Irrespeetive of the igeometrical shape of the blank, and as will be better understood from the following description, containers assembled from such blanks have, exposed to the liquid in the container, a paperboard edge. The instant invention is concerne-d with such exposed edge and not with the particular shape of the blank.

Referring now to FIGURE 1, ilat blank 2, cut from a larger sheet of coated paperboard, is embossed at vertical lines 4, 6, 8, 10 into body panels 12, 14, 16 and 18 and side seam panel 20. Each panel, 12 through 20, is divided by embossed horizontal lines 22, 24, approximately perpendicular to embossed lines 4, 6, 8, 10, into top sections 12a, 14a, 16a, 18a, 20a, side sections 12b, 14b, 16b, 18b, 20b, and bottom sections 12e, 14e, 16C, 18C, 20c. Each of the top sections is embossed along fold lines to form, when folded, a top closure. Further description of the top sections is not necessary for an understanding of the instant invention.

Side sections 12b, 14b, 16b, 18b,f20b and bottom sections 12c, 14C, 16e, 18C, 20c form the vertical sides and bottom of the assembled container. Bottom sections 14o, 18e are each divided into triangular shaped sections, by embossed diagonal lines 30, 32 and 34, 36. Thus, bottom Section 14c is divided into three triangular portions 38, 40, 42 and bottom section 18e into three triangular portions 44, 46, 48.

Conventionally, the paperboard container blank is assembled, or erected, by machine, part of the assembly occurring after the blanks are cut and embossed and the balance occurring where the containers are filled. For ease and convenience in shipping and storage, it is customary practice for the manufacturer of the blanks to fold the blank, seal the side seam and ship the folded blank liat. The folded and side seamed blank is opened into the rectangular container, the bottom closure is folded and sealed, the container is filled and the top closure is folded and sealed where the containers are filled. All of these folding and sealing operations are performed by conventional machines, not described here.

In the initial assembly of the blank, the surfaces of side panel 12 and seam panel 20 which, when brought into contact with each other, adhere and form a liquid tight seam, are heated to soften the thermoplastic, or polyethylene, coating and side panel 18 is folded onto side panel 16 along embossed line 8. Seam panel 20 projects beyond embossed line 6 onto side .panel 14. Side panel 12 is then folded along embossed line 4 onto side panel 14 and the heated surface at the end of side panel 12 is brought into contact with the heated surface of seam panel 20. Pressure is then applied to seam panel 20 and the thermoplastic coating is cooled to form a liquid tight seam between the mating surface of panels 12 and 20. The folded and seamed blanks are then packaged and shipped.

As the containers are to be filled, the balance of the assembly, or erection, of the containers is completed. The seamed blanks are opened out into a rectangular container, end panels 14, 18 are folded along embossed lines 30, 32 and 34, 36, respectively, and inwardly along embossed lines 24 toward the center of the container, end panels 12, 16 are folded inwardly and the end of the container is sealed. The container is then filled and the top sections are folded inwardly and sealed. The `filled containers can then be shipped.

As shown in FIGURE 4, the container blank is made up of a paperboard center coated on its opposite faces with a thermoplastic coating, such as polyethylene. When the blank is cut from the paperboard sheet and embossed, the thermoplastic coating on the opposite faces of the sheet remain intact and form a liquid proof barrier, or coating, on the faces of the blank. However, the cut edges of the paperboard center of the blank are uncoated and exposed. Thus, the edge of seam panel 20 which, when the container is assembled, is in the inside of the container, will be exposed to the liquid contents of the container.

In the instant invention, the paperboard between the thermoplastic, or polyethylene, coatings is impregnated with a thermoplastic material, such as wax, after the container blank is cut from the coated sheet and embossed and before the initial assembly or erection of the container. As best shown in FIGURES 1 to 4, the paperboard core 50 is impregnated at 52 with wax in a continuous area extending above and below embossed line 24 and into the paperboard core. As will be described, this impregnation is accomplished after the paperboard core is coated and the blank is cut from the coated sheet. The impregnation does not interfere with the coating, nor with conventional erection and sealing, but prevents wicking or wetting of the paperboard core by the liquid container contents and weakening of the seam and leakage resulting therefrom.

Referring now to FIGURES and 6, container blanks 2 are stacked, one on the other, and the edges of the container blanks to be impregnated are advanced past the front of heat source 60. The edge portion to be impregnated is heated to a temperature receptive to the impregnate, but not high enough to soften and cause sticking of the thermoplastic coating on the surfaces of the blanks. With the edge portion thus heated, the thermoplastic material, such as Wax, is brought into contact with the heated edge and the wax is taken up, absorbed or adsorbed by the paperboard core. Preferably, the wax is heated and brought into contact with the paperboard edge by an application, such as coater roller 62 rotated, in the direction of the arrow in FIGURE 5, through heated wax supply reservoir 64. Treated cartons are removed from the bottom of the stack by conveyer 6-6.

The thermoplastic material, or wax, in the treatment of the paperboard edge at the bottom area of the side seam and at the bottom seam of the instant invention, is taken up and flows into the paperboard between the thermoplastic coated surfaces and migrates through the edge into the paperboard. The depth of migration into the paperboard and length of the edge treated can, of course, be varied so long as the line of impregnation is continuous and extends through the fold between the side and bottom.

Migration of the thermoplastic material to a depth not less than one-sixteenth of an inch and not greater than four-sixteenths of an inch, in a continuous path along the side and bottom seals of not substantially less than one and eleven-sixteenths of an inch and not substantially more than two and ten-sixteenths of an inch, with the path continuous and divided substantially equally between the side and bottom seams, has been found satisfactory. A depth of migration of one-eighth of an inch and a continuous path of two inches, divided substantially equally in the side and bottom seams, is preferred.

The thermoplastic material taken up by the paperboard core in the area treated makes the edge of the board liquid repellent or hydrophobic in the treated area but does not interfere with the assembly, or erection, and sealing of the container in the conventional manner. Furthermore, when the bottom panel is folded to form the bottom closure, the treated edge retains its liquid repellency. The container, when filled, may be shipped over extended distances and stored for prolonged periods even when filled with liquids, such as orange juice, that have, in the past, been found to be most prone to leakage from coated paperboard containers.

202,000 one quart paperboard container blanks, cut from paperboard stock coated on its opposite surfaces with polyethylene were treated in accordance with the instant invention. The container blanks were stacked, one or the other, and advanced in a continuous stream so that the edge of the blanks to be impregnated advanced past a heater and heated to a temperature not substantially less than F. and not substantially more than 130 F. The area of the edge to be impregnated was thus heated and parain wax, maintained at a temperature of plus or minus 2 F., was brought into contact with the heated edge of the container blank as the blanks advanced past the applicator. The treated blanks were then removed.

Approximately 58,000 container blanks were treated for each pound of wax consumed. The average depth of wax penetration into the edge of the treated blanks was 3/16 of an inch and the average length along the edge of the blank was 2% inches. The containers were assembled by machine in the conventional manner, tested for side seam bonding and bottom sealing. The seams were found well bonded and the bottoms properly sealed. The containers did not leak.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible.

What is claimed is:

1. A coated paperboard container blank intended to be erected into a container for liquid and having portions to be included in side walls, bottom walls, and a side and bottom wall sealing seam of an erected container, said blank having a paperboard edge which, when the container is erected, will be in said side and bottom sealing seam and exposed to the liquid contents of the erected container, and a thermoplastic impregnate material in said paperboard edge extending inwardly into the paperboard in said sealing seam portion behind the coating on said paperboard and extending axially in a continuous path in said paperboard edge behind said coating from a point in the side wall portion of said sealing seam to a point in the bottom wall portion of said sealing seam.

2. A coated paperboard container blank as recited in claim 1, in which said thermoplastic material is wax.

3. A coated paperboard container blank as recited irl claim 2, in which said thermoplastic material extends inwardly into the edge of said paperboard for not substa11-i tially less than one-sixteenth of an inch and not substantially more than four-sixteenths of an inch.

4. A coated paperboard container blank as recited in claim 3, in which said thermoplastic material extends axially into said edge of said paperboard in a continuous path in said paperboard edge not substantially less than one and eleVen-sixteenths of an inch and not substantially more 4than two and ten-sixteenths of an inch divided substantially equally between said side and bottom sealing seam portions.

5. A coated paperboard container for liquid having side walls, a bottom Wall, a side sealing seam extending along one of said side walls into the bottom wall, a paperboard edge exposed in said container to said liquid contents extending along said sealing seam, and a thermoplastic impregnate material in said paperboard edge extending inwardly into the paperboard in said sealing seam portion behind the coating on said paperboard and extending axially in a continuous path in said paperboard edge behind said coating from a point in the side Wall portion of said sealing seam to a point in the bottom wall portion of said sealing seam.

6. A coated paperboard container as recited in claim 5, in which said thermoplastic material is wax.

7. A coated paperboard container as recited in claim 6, in which said thermoplastic material extends inwardly into the edge of said paperboard for not substantially less than one-sixteenth of an inch and not substantially more than four-sixteenths of an inch.

8. A coated paperboard container as recited in claim 7, in which said thermoplastic material extends axially into said edge of said paperboard in a continuous path in said paperboard edge not substantially less than one and eleven-sixteenths of an inch and not substantially more than two and ten-sixteenths of an inch divided substantially equally between said side and bottom sealing seam portions.

References Cited UNITED STATES PATENTS 2,290,741 7 1942 Eckert 117-37 XR 2,279,382 4/ 1942 Swenson. 2,282,898 5/ 1942 Snader et al. 117-37 2,415,387 2/ 1947 Graebmer et al. `2,474,619 6/ 1949 Farrell et al.

3,081,213 3/1963 Chinn. 3,116,002 12/ 1963 Crawford et al 229-17 3,189,246 6/ 1965 Seline 229--17 DAVIS T. MOORHEAD, Primary Examiner U.S. Cl. X.R. 229--3.1

P04050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,098,527 Dated March 3, 1970 Inventads) Moors et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. l, line 56, "cnotact" should read contact --5 lines 65-66, should read "the side wall at the bottom of the container and that this vibration causes the liquid in the container to selnp or";

Col. Ll, line 29 "or" should read on SIGNED AND SEALED n JUL 2 81970 (SEAL) Attest:

Edwrd M' dan WILLIAM E. somma, JR. Attestng Officer onmissioner of hunts

Images