US 3094269 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
June 18, 1963 w. s. SCHNEIDER 3,094,269
CONTAINER WITH A BUTT SEAM Filed May 1, 1959 (mmmnnu um:
INVEN TOR. I mL/HM 5. 5c/0vE/0E/g United States Patent M 3,094,269 CONTAENER WITH A BUTT SEAM William S. Schneider, Glendale, Califi, assignor, by direct and mesne assignments, to Packaging Frontiers Inc., a corporation of Delaware Filed May 1, 1959, Ser. No. 810,304 5 Claims. (Cl. 22986) The present invention relates generally to containers or packages; and more especially to flexible containers that are made from sheets or webs of thin flexible materials, such as paper, foil, plastic, or combinations of these materials.
In the .art of making containers, it is well known to start with a web which is unwound from a roll as a flat element and is fed continuously into a machine wherein the web is shaped around a tubular mandrel to assume a tubular formation. Portions along opposite sides of the web are brought together in forming the tube and are subsequently joined together in a suitable manner to form a seam that extends longitudinally of the web. One wellknown type of seam is the overlapping seam in which marginal portions along opposite edges of the web are brought into overlapping relation and then sealed together. This seam and apparatus for making it are well known in the art and are disclosed in US. Patent No. 2,741,079 issued April 10, 1956, to R. Rausing for Apparatus for Continuous Production of Filled and Sealed Tetrahedral Packages of Paper or the Like.
After the web is formed into a tube, the material to be packaged is fed into the tube. The individual packages are then completed by making spaced seals extending transversely across the tube at intervals along the length of the tube. If successive transverse seals are all located in a common plane, the package produced is a flat envelope-type package. If the successive seals are located in planes at substantially 90 to one another, as is shown in the Rausing patent referred to above, the packages produced have a tetrahedral shape. Packages of other shapes may likewise be produced from the tube into which the flat web has been formed.
The overlapping type of longitudinal seam has been widely used for many reasons in making packages from a continuous web. However, a seam of this type has some serious disadvantages. For example, in the case of webs which are sealed by the application of heat and pressure, it is necessary to use a web which is heat-sealable on two sides. This requirement exists because of the overlapping character of the seam. This requirement imposes a severe limitation upon the range of materials that may be used for making containers since by far the largest proportion of webs now commercially available for making containers are heat-sealable on one side only.
Another serious disadvantage of a longitudinal seam of the overlapping type is a condition commonly referred to in the trade as wicking. To understand this problem it should be realized that the web or stock from which is made a container of the type with which we are here concerned, is frequently of a character to absorb liquids. In the case of laminated webs consisting of two or more layers of different materials, one of the inner layers, contributing thickness and stiffness to the Web, may be moderately absorbent. Such a layer is usually made of paper or other cellulosic material. It is common practice to coat the absorbent layer with a layer of moistureresistant material which makes the web heat-sealable and prevents direct contact between the liquid contents and the absorbent layer. However, when the conventional overlapping seal is used, this barrier to moisture, provided by the moisture-resistant inner coating is broken at the cut edge of the stock which is exposed on the inside of the container to the liquid contents. At this cut edge, the
3,094,269 Patented June 18, 1963 absorbent layer can absorb enough liquid that its softens or disintegrates, weakening the longitudinal seam and eventually causing it to leak.
In general, the longitudinal seam presents something of a problem in a container made from a continuous web because of the desire to make the seam as inconspicuous as possible. In a container of tetrahedral shape it is desired to have the seam entirely on one side of the container. It will be noted that in the container of this shape disclosed in the Rausing patent mentioned above, the longitudinal seam crosses part of two of the four sides of the container and as a result is always visible to some extent. When the seam is on one side only, it can be hidden by resting the container upon that side. A particular advantage of this construction is that the entire area of the remaining three sides is free for printing, art work, or similar displays. To locate the longitudinal seam entirely on one side of a tetrahedron, the seam must start at one end of one of the transverse seals. When the seam is formed by overlapping the Web and is located at the end of a transverse seal a fold at the end of the transverse seal must be made through three or four thicknesses of the web. This thickness of stock resists folding and is hard to perform satisfactorily in high speed machines. There is a marked tendency for the seam to break open at such a fold, causing the package to leak.
Therefore it becomes a general object of my invention to provide a container, made from a continuous web of thin flexible material, with a longitudinal seam such that no cut edge of the web is exposed to the contents and therefore the container wall is not subject to wicking or the absorption of liquid from the contents.
Another object of the invention is to provide a container with a longitudinal seam that has the above advantages and that permits the container to be manufactured from webs that can be heat sealed on one side only.
A further object of the invention is to provide a longitudinal seam construction which enables the container to be made with transverse seals requiring folding of only .a single thickness of web and formed by the application of heat and pressure for closing the ends of the tube.
Another object of the invention is to provide a container having a longitudianl seam which leaves the maxi mum number of sides of the container free for printing, art work, or the like.
Another object of the invention is to provide a seam construction for a container of the character described which permits incorporation in the seam of novel means for progressively opening the container at the seam.
The above objects of the invention have been attained in a preferred form of container comprising a web of thin, flexible material formed into a tube with opposite longitudinal edges of the web brought into abutting relation. A sealing strip is located inside the tube and is sealed to marginal portions of the web adjoining both edegs to form a longitudinal seam extending for the length of the tube and closing the tube. The package is completed by spaced closure means at each end of the tube. While not necessarily limited to any specific means, such closure preferably consists of marginal portions of the tube heat sealed together inside-face-to-inside-face.
.Such a seam and end seal can be provided with a Web which is heat sealable on one side only by placing the heat sealable side on the inside of the container. The sealing strip is heat sealable on two sides and consequently seals not only to the marginal portions of the web adjoining the abutting edges but also seals to the op posite wall of the container where the strip passes through the transverse seals at the ends of the packages.
I prefer to incorporate in the sealing strip a tear string which is located centrally of the strip and which may be pulled out between the abutting edges of the web to rip the sealing strip apart along these edges. The tear string is particularly adapted to controlled or progressive opening of the package which, in the case of a tetrahedron, for example, permits the opening through which the contents are removed to be progressively expanded as the level of the contents is lowered.
When the transverse end seals lie substantially in planes of 90 to each other to form a tetrahedral shaped container, the longitudinal seam is located in the tube to extend from one lateral end of one end seal across a single triangular side of the container and centrally across the other end closure. In this position the seam can be located entirely on the bottom of the container.
A butt type longitudinal seal of this character produces a neat, unobvious seam which contributes materially to a pleasing appearance to a package. It also permits a design or a text printed on the exterior surface of the container to occupy three of the four sides within any break or interruption caused by a seam and even extend across the seam with only a minimum interruption since the surface containing the seam is substantially continuous.
How the above objects and advantages of my invention, as well as others not specifically mentioned, are attained will be more easily understood by reference to the following description and to the annexed drawing in which:
FIG. 1 is a side elevation of a tetrahedral container embodying my invention.
FIG. 2 is a plan view of the container of FIG. 1.
FIG. 3 is an enlarged fragmentary section on line 33 of FIG. 1, the thickness of the web and sealing strip being exaggerated for purposes of illustration.
FIG. 4 is an enlarged fragmentary section on line 44 of FIG. 1, the thicknesses of the web and strip again being exaggerated.
FIG. 5 is an enlarged fragmentary side elevation of the upper corner of the container of FIG. 1.
FIG. 6 is a view similar to FIG. 5 illustrating an initial step in opening the container.
' 'FIG. 7 is a diagram illustrating steps in the formation of the longitudinal seam.
FIG. 8 is a plan view of an opened tetrahedral container illustrating how the opening may be progressively expanded.
FIG. 9 is a perspective of a fiat container embodying my invention.
Referring now to the drawing, there is shown in FIGS. 1 and 2 a completed container C of tetrahedral shape illustrating a preferred embodiment of the invention. The construction of the container is most easily understood by describing various steps involved in the manufacture of the container, as will now be done.
Making containers of various shapes from a continuous web is so well known in the art as to make unnecessary the recitation in detail of all the steps involved in the forming and/or shaping of the web and appaartus therefor. Commonly, the operation of forming containers starts with unrolling the web as a continuous, planar member from a roll. The web is then formed around a mandrel of suitable size and shape to produce a tubular member. Such an operation is disclosed in Rausing Patent No. 2,741,079 mentioned above.
The web W is illustrated diagrammatically in FIG. 7 after it has assumed this tubular shape. The web W may be considered as being any one of a number of thin, flexible materials that is heat scalable on the face which becomes the inner face of the tube and the subsequent container. Of course the invention is not limited to materials which are heat scalable on one face only. Usual and typical materials are paper stock coated with a waterresistant sealing compound, of a laminated stock which includes a core layer of paper, a coating of synthetic resin or a plastic substance, and an outer layer of metal foil.
Various other combinations of material are available and may be used but a typical laminated web W of this latter construction is illustrated in FIG. 4.
The metal foil 11 is placed on the outside of the completed package and normally carries printing, art work, or the like that contributes to the appearance of the package. The coating of synthetic resin 12 is placed on the inside of the package where it provides a barrier to absorption of moisture by paper core 14 from the contents of the package. The layer of paper or board 14 is absorbent material and must be protected from receiving moisture from the contents of the container if the seal is to remain strong. The inner coating 12 is usually of such a character as to render the inner face of the web heat scalable by the application of heat and pressure.
When the web is formed into a tubular shape as shown in FIG. 7, the longitdinal edges 15 and 16 at opposite sides of the web are brought together in abutting relation as shown in FIG. 4. In this position, marginal portions 17 and 18 of the web adjoining edges 15 and 16 respectively, both overlie sealing strip 20. The sealing strip is a continuous member placed inside the tube and extending parallel to abutting edges 15 and 16. When the parts are in the position shown in FIG. 7, the marginal portions 17 and 13 of the web adjoining edges 15 and 16 can be sealed to strip 20 by the application thereto of heat and pressure. This may be accomplished by a member 21 applying pressure in the direction of arrow 22 to press the web against sealing strip 20. The sealing strip may be backed up by suitable abutment member 24 which typically may be the mandrel around which web W is shaped. It will be understood that heat may be applied to the joint by any suitable means, as by a heated member 21 or by a high frequency electromagnetic field.
Sealing strip 20 is itself scalable on two sides and may be of any construction or material providing this characteristic. As one example of a suitable material, but without limiting the invention thereto, sealing strip 20 may be a homogeneous strip of thermoplastic resin such as polyethylene. Also by way of example, another suitable sealing strip is a product marketed by Minnesota Mining and Manufacturing Company under the trade name Scotch- Pak and which is a polyester film coated on both sides with a sealing coat which will seal to itself and also to many other laminated stocks commonly used for making packages or containers. Either of these sealing strips are moisture resistant and adequately protect the cut edges 15 and 16 of the web from any contact with moisture inside the completed container.
To prevent the sealing strip from adhering to abutment 24, the latter member may be made from or coated with some substance to which the strip does not adhere, for example, a tertafiuoroethylene polymer, commonly known as Teflon.
Each package is completed by compressing the tube in a zone extending transversely across the tube to bring together opposing walls of the tube. The web material being heat sealable on the inside face, a transverse seal is made by the application of heat and pressure at the time of compressing the walls to bring them together in faceto-face relation. As a result, the walls are sealed together inside-face-to-inside-face. In its broader aspect the present invention is not necessarily limited to a transverse seal of this character since under some circumstances other suitable types of closure may be used, including pressure sensitive or water soluble adhesives, staples, and so on.
These transverse seals are ordinarily formed one at a time and in succession at spaced intervals along the length of the tube. Since each transverse seal closes the lower end of the tube, a charge of contents can then be placed in the tube above the seal. Then another transverse seal is placed across the tube above the contents to complete the package and enclose the contents. Individaul packages are severed from the tube by cutting through the tube at one of the seals. Each of the transverse seals thus provides a portion of the sealed area 25 or 26 located at each end of the tube segment which becomes an individual package. As seen in FIGS. 1 and 2, the two end seals 25 and 26 are substantially in planes at approximately 90 to each other, thus producing a four-sided container having four similar triangular sides.
Because sealing strip is heat scalable on both sides or faces, it seals readily either to itself where it passes through seal or to the opposing wall of the container where it passes through end seal 26. This characteristic insures that both end seals are unbroken by the presence of strip 20 and that the contents of the container will not leak or sift out through any minute opening at or around the location of the sealing strip as it passes through the end sealed areas.
In placing the transverse seals, the seal 25 is so located that strip 20 is folded back upon itself where it passes through the seal 25 and is thus located at one lateral end of the elongated sealed area. From this location the longitudinal seam formed by the sealing strip passes over only one triangular side of the container, as shown in FIG. 2. In a symmetrical package the seam bisects this side of the package. Accordingly, the seam and the sealing strip are located centrally of the other end seal 26.
To obtain the most favorable appearance, the container as so far described can be displayed with the longitudinal seam completely hidden. This is done by resting the package on the side which is shown uppermost in FIGS. 1 and 2. The one side crossed by the seam is thus at the bottom of the package where the seam is not seen. The other three sides of the container present smooth, uninterrupted surfaces to receive printing or designs of any character without any discontinuity created by the presence of the longitudinal seam crossing a portion of the side. A butt seam as described, when located at an end of one of the tnansverse seals, eliminates any problem of folding through multiple thicknesses, and produces a completely reliable seal at the ends of the container.
In a preferred embodiment of my invention, sealing strip 20 includes a tear string attached to the inner face of the sealing strip and extending longitudinally of the strip midway between its longitudinal edges. In making the container, this tear string is located directly beneath the abutting edges 15 and 16 of the web. While these abutting edges may be in contact with each other, it is preferred that they be not in contact with each other but very closely spaced'(FIG. 4) when the tear string is provided. This tear string can then be more easily pulled out between the two edges, ripping apart the sealing strip to provide an opening in the container wall. This is facilitated by making the sealing strip of lesser strength than the web constituting the container wall.
As shown particularly in FIGS. 3 and 5, the tear string 30 crosses sealed area 25 at a position very close to one lateral edge. At this location on the container, the edges 15 and 16 of the web are disposed substantially in a common plane and the tear string can be pulled out from between them by tearing through only the thickness of the sealing strip.
When the completed container is severed from the tube by making a transverse cut in sealed area 25, the tear string is cut flush with the end of the container. In order to free it for purposes of opening the package, sealed area 25 is formed with a line of Weakness which intersects the tear string, preferably at or near the inner end of the sealed area. A preferred means for defining this line of weakness is a row of small, closely spaced perforations 32 commencing at the outer end of the container and extending inwardly across sealed area 25 to intersect the tear string. The sealed area can be torn with relative case from one perforation to the next, permitting a triangular corner 34 to be torn off as shown in FIG. 6. The terminal portion of tear string 30 is now free and the string can be pulled from left to right in FIG.
1 along the longitudinal seam and between edges 15 and 16 to tear the sealing strip 20.
It will be noticed that the opening 35 made in the container starts at the highest point of the container so that none of the contents spill or leak out when the opening is first made. The size of the opening can be made as large as desired by pulling the tear string a greater or lesser distance from the seal 25. This is a particularly useful characteristic in the case of a food product packaged in the container which can be eaten with a spoon. As the contents are removed and their level drops, the opening can be progressively enlarged as indicated at 35a and 35b in broken lines in FIG. 8 to provide continuing ease of access to all portions of the container.
In the case of a tetrahedral package made of transparent material, it is difficult to measure by eye the quantity remaining in the package, when partially emptied, because the volume of the contents is not in direct proportion to the height of the contents above the bottom. When desired or necessary to make a close estimate of the volume of the contents, a scale 40 is printed on the outside of the container. Such a scale may be graduated in any unit of volume, such as ounces, cubic centimeters, and the like. A scale of this character permits the user to measure a specific quantity of the contents emptied from the container or to determine from inspection by reference to the scale the volume or quantity of the contents remaining in the partially emptied container. Obviously, because of the shape of the container the utility of such a scale depends upon its accurate positioning upon the package and more particularly with respect to one of the seals. While in general the scale must be positioned properly between the two end seals 25 and 26, it more particularly is located at a fixed distance from the end seal 25 or 26 to measure the contents. Printing may also be placed on the Web in a predetermined position to be adjacent the line of weakness established by perforations 32 which are formed at the time that sealed area 25 is formed. Such printing would include instructions to the user for freeing the end of the tear string and using it to open the container.
In some of its aspects, my invention can be embodied in a flat or envelope type container having two principal sides, as illustrated in FIG. 9. In this type of container, the end seals 37 and 38 are substantially in a common plane instead of being rotated with respect to one another as is the case with end seals 25 and 26. The longitudinal seam is formed in the manner described above and is located at the end of at least one of the transverse seals. A section through the end of transverse seal 37 would appear as in FIG. 3. However, since the two seals 37 and 38 are in the same plane, the longitudinal seam continues down an edge of the package, the abutting edges of the web being indicated at 39. Hence the sealing strip 20 in this type of package crosses both end seals 37 and 38. A row of perforations 32 or other means establishing a line of weakness may be provided to facilitate freeing one end of the tear string, as already described. The package is thus opened along one edge rather than across one of its principal faces and the two large exposed surfaces on the package are left free and uninterrupted for printing, art Work and the like.
From the foregoing it will be realized that various changes in the design and construction of packages are possible within the scope of my invention; and accordingly it is to be understood that the foregoing description is considered to be illustrative of rather than limitative upon, the invention as defined by the appended claims.
1. A filled package comprising a tube formed from a Web of flexible packaging material and being heat-scalable on the inside, the longitudinal edges of the web being contiguous and secured together by a sealing strip on the inside of the tube, said strip being heat-scalable on both its faces and lapping and heat-sealed to the longitudinal margins of the web thereby providing a longitudinal tube seam, each end of the tube being closed by a transverse inside-face-to-inside-face heat seal, one of said transverse seals comprising an end portion of the tube flattened in such a plane that the portion of the Web included therein is folded on a fold line at one end of said one transverse seal and the longitudinal edges of said portion of the Web are located at the corner of the package at the other end of said one transverse seal with the end portion of said strip at said corner folded on a fold line at said other end of said one transverse seal, a tearing member secured to said strip on the inside thereof extending longitudinally of the strip substantially in register with said contiguous longitudinal edges of the Web, the interengaging faces of said folded end portion of said strip being heat-sealed together about the tearing member with said tearing member terminating at the ends of said strip within said transverse seals, and a line of weakness at said corner extending inward from the respective end of the tube across said one transverse seal and across the respective end portion of said strip to provide a tear-off corner portion of said one transverse seal and said strip for freeing the respective end of the tearing member whereby the tearing member along with the tear-oif corner portion heat-sealed thereabout may be gripped and pulled to tear the strip between the contiguous edges of the Web.
2. A filled tetrahedron-shaped package comprising a tube formed from a web of flexible packaging material and being heat-scalable on the inside, the longitudinal edges of the web being contiguous and secured together by a sealing strip on the inside of the tube, said strip being heat-sealable on both its faces and lapping and heat-sealed to the longitudinal margins of the web thereby providing a longitudinal tube seam, each end of the tube being closed by a transverse inside-face-to-inside-face heat seal, each of said transverse seals comprising a flattened end portion of the tube, one of said transverse seals being flattened in such a plane that the portion of the web included therein is folded on a fold line at one end of said one transverse seal and the longitudinal edges of said portion of the web are located at the corner of the package at the other end of said one transverse seal, the
end portion of said strip at said corner being folded genorally in half on a longitudinal fold line at said other end of said one transverse seal with the adjacent faces of the folded end portion being heat-sealed together, the other transverse seal being flattened in a plane at such an angle to the first-mentioned plane as to form a tetrahedron-shaped package with four triangular sides, and said longitudinal seam including said strip extending from said corner across one triangular side only of the package and across the other transverse seal between the ends of the latter, the other end portion of said strip lying flat and unfolded within said other transverse seal.
3. A filled tetrahedron-shaped package as set forth in claim 2 further comprising a tearing member secured to said strip on the inside thereof extending longitudinally of the strip substantially in register with said contiguous longitudinal edges of the web adapted for being pulled to tear the strip between the contiguous edges of the Web.
4. A filled package as set forth in claim 3 wherein the adjacent faces of the folded end portion of the strip are heat-sealed together about the tearing member and said tearing member terminates at the ends of said strip within said transverse seals and wherein a line of weakness is provided at said corner extending inward from the respective end of the tube across said one transverse seal and across the respective end portion of said strip to provide a tear-off corner portion of said one transverse seal and said strip for freeing the respective end of the tearing member.
5. A filled package comprising a tube formed from a web of flexible packaging material and being heat-sealable on the inside, the longitudinal edges of the web being contiguous and secured together by a sealing strip on the inside of the tube, said strip being heat-sealable on both its faces and lapping and heat-sealed to the longitudinal margins of the web thereby providing a longitudinal tube seam, each end of the tube being closed by a transverse inside-face-to-inside-face heat seal, each of said transverse seals comprising a flattened end portion of the tube, each transverse seal being flattened in the same plane with this plane such that the portion of the web included in each transverse seal is folded on a fold line at one end of the transverse seal and the longitudinal edges of said portion of the web are located at the corner of the package at the other end of the transverse seal, said strip being folded throughout its length on a fold line defining one side edge of the package and said strip having its end portions included in the corners of the packages at the ends of said side edge of the package, a tearing member secured to said strip extending longitudinally of the strip within the fold of the strip, the interengaging faces of said folded end portions being heat-sealed together about the tearing member with said tearing member terminating at the ends of said strip within said transverse seals, and a line of Weakness at one of said corners extending inward from the respective end of the tube across the respective transverse seal and the respective end portion of said strip to provide a tear-off corner portion of this transverse seal and the strip for freeing the respective end of the tearing member whereby the tearing member along with the tear-off corner portion heat-sealed thereabout may be gripped and pulled to tear the strip along the fold thereof.
References Cited in the file of this patent UNITED STATES PATENTS 180,773 Magruder et a1 Aug. 8, 1876 1,155,740 Lacroix et al. Oct. 5, 1915 1,853,013 Brady Apr. 5, 1932 1,936,417 Ware Nov. 21, 1933 1,978,035 Thom Oct. 23, 1934 2,169,936 Wagner Aug. 15, 1939 2,226,936 Flood Dec. 24, 1940 2,565,622 Orr Aug. 28, 1951 2,699,285 Bell et al. Jan. 11, 1955 FOREIGN PATENTS 246,680 Switzerland Oct. 1, 1947