US3111796A

US3111796A - Method for closing and sealing containers

Info

Publication number: US3111796A
Application number: US102011A
Authority: US
Inventors: William E Meissner
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1961-04-10
Filing date: 1961-04-10
Publication date: 1963-11-26
Anticipated expiration: 1980-11-26

Description

Nov. 26, 1963 w. E. MEISSNER "METHOD FOR CLOSING AND SEALING CONTAINERS Filed April 10, 1961 United States Patent 3,111,796 liiETI-IGD FUR CLUSING AND SEAMNG CQNTAENERE? William E. Meissner, Devon, Pa, assignor, by mesne assignments, to FMC @erporation, San .iose, Calif, a corporation of Delaware Filed Apr. 10, 1961, st. No. 192,611 8 Claims. (Cl. 53-38) The invention rel-ates to an improved method for closing and sealing containers.

in packing articles of flowable materials in preformed flexible or collapsible containers, such as bags, a common practice is to merely close the open end of the container as by folding or twisting and then fix the same with a tape, cord, or metal fastener. in applications where a more secure or perhaps leakproof closure is required, the container may be heat-sealed or alternately sealed with an adhesive compound. Heat-sealing procedures of course require that the container be formed of or at least coated with a thermoplastic material and often demand exacting operating conditions to facilitate the formation of a strong and uniform bond without damaging either the container or its contents. Employing adhesive compounds, on the other hand, entails the use of various forms of applicators which do not insure an even distribution of the adhesive compound to all areas of the surfaces to be coated. Accordingly, a primary object of this invention is to provide a new or improved and more satisfactory method for closing and sealing preformed containers.

Another object is the provision of an improved method for closing and sealing a collapsible container by rupturing a bubble of tacky film-forming material at least partially within the open end of the container as that portion of the container is urged into a collapsed position.

Still another object is to provide an improved method wherein at least one mass of tacky film-forming material is expanded into the form of a bubble within the open end of a container and then ruptured to provide a uniform and continuous tacky lining on the adjacent surfaces of the container.

A further object is the provision of a method wherein at least one mass or gob of tacky film-forming material is inflated into the form of a bubble within and/ or across the open end of the container and then ruptured as portions of the container itself are urged into collapsed position to provide an adhesive lining on the adjacent container surfaces.

These and other objects and advantages of the invention will become apparent from the following description and ccompanying drawing in which:

FIGURE 1 is a diagrammatic view illustrating a mass of film-forming material being initially expanded into the form of a bubble within the open end of a container;

FIGURE 2 is a View similar to FIGURE 1 showing a bubble of film-forming material as it is deformed during the initial collapse of the container open end;

FIGURE 3 illustrates the container of FIGURE 2 as the bubble of film-forming material is ruptured during collapse of the open end of the container;

FIGURE 4 is a view similar to FIGURE 1 illustrating the inflation of a mass of film-forming material within the open end of a container having non-self supporting flexible Walls;

FIGURE 5 shows the container of FIGURE 4 as closed and sealed by a twisting of a portion thereof;

FIGURE 6 is a view similar to FEGURE 1 illustrating a modified procedure for applying adhesive to a container having an elongated open end; and

FIGURE 7 is a view similar to FIGURE 6' illustrating a still further modified procedure for applying adhesive to a container having an elongated open end.

ice

In general, the present invention relates to closing and sealing of containers, and particularly to a method wherein a mass or gob of film-forming material is suspended within the open end of a container, expanded into the form of a bubble, and then ruptured concomitantly as the open end of the container is collapsed to provide a continuous and uniform adhesive coating along the adjacent internal surfaces of the container walls. During the collapse of the open end of the container, and prior to rupture of the expanded bubble of film-forming material, the bubble is deformed into conformity with the adjacent surfaces of the container walls and thereby progressively lines the same with a continuous adhesive coating which remains in place after bubble rupture.

In accordance with a modified procedure of the present invention, a mass of film-forming material may be eX' panded into the form of a bubble concomitantly as the mass of film-forming material is moved relative to or across the open end of a container. As a further alternative, a series of bubbles of film-forming material may be expanded within the open end of a container so as to together cooperate to adhesively line or coat the internal surfaces of the container walls as the open end thereof is collapsed. These particular procedures are well adapted for sealing containers having relatively wide or elongated open ends and provide for a continuous and uniform adhesive coating along the internal surfaces of the container walls in much the same manner as heretofore mentioned.

Control over the areas of the container walls coated with the adhesive film-forming material may be achieved by selectively positioning the expanded bubble or bubbles of film-forming material relative to the open end of the container. An alternative and preferred procedure for achieving more accurate control however, is to vary the size of the expanded bubble or number of bubbles so that L16 internal surfaces of the container walls, or at least the major portions thereof, engage with the expanded bubble or bubbles of film-forming material only during the terminal stage of the container collapsing operation.

The thickness of the adhesive coating applied to the internal surfaces of the container walls can be regulated by varying the amount of film-forming material, the degree of inflation thereof or the number and size of the bubbles of film-forming material employed. Thus, where a relatively thick adhesive coating is desired, a relatively large mass of film-forming material may be initially applied, or alternatively, additional film-forming material may be supplied concomitantly with the inflation thereof into a bubble form.

A wide variety of film-forming materials which are of a tacky or adhesive character when rendered plastic or flowable may be employed in the practice of the present invention. Preferred types include the synthetic linear polymers of thermoplastic character and the elastomeric types. Examples include vinyl resins, such as polyvinyl acetate, copolymers of vinyl chloride and vinyl acetate, copolymers of acrylonitrile and vinyl acetate, polyacrylonitrile and copolymers of acrylonitrile With vinyl chloride, vinyl acetate, methacrylonitrile, and so forth, polyethylene, linear superpolymers of the polyester of nylon (polyamide) type, polyvinyl butyral, polyvinyl alcohols, polyvinyl ethers; elastomeric types may include neoprene, polymers of chloroprene, copolymers of butadiene with styrene or acrylonitrile, polyisobutylene, and so forth. It is to be understood that the mentioning of these particular materials is not intended to limit the invention thereto but merely to illustrate the wide variety of film-forming materials that can be used in carrying out the invention.

The film-forming material may be converted into a fiowable mass or gob by fusion or by the incorporation of plasticizers or solvents capable of dissolving or dispersing the material. Thus, any of the thermoplastic materials may be heated to fusion after which the inflating medium may be introduced into a gob thereof, preferably at the same temperature as the fused material. If necessary, the temperature of fusion may be lowered by the incorporation of a plasticizer either of solid or liquid charac er. When plasticizers or solvents are incorporated into the plastic material to form the gob, the plasticizer or solvent is preferably non-reactive with the inflating medium. The cooling of the fused plastic mass, with or without plasticizers, is effected as the expanded bubble or envelope of film-forming material progressively lines the adjacent internal surfaces of the container walls during the collapse of the containcr open end.

Volatile solvents may be employed for dissolving or dispersing the film-forming material so that a gob thereof may be formed at room temperature and expanded, with the setting or coagulation of the expanded bubble, after application to the container walls, occurring by volatilize- -tion of the solvent. Known solvents and plasticizers may be employed, the selection depending upon the particular filmiorming material to be used. Thus, acetone or dioxane may be used for vinyl acetate or copolymers of vinyl acetate or vinyl chloride or acrylonitrile. The concentration of the film-forming material, when a solution thereof is used, is preferably as great as possible and is limited only by the necessity that the plastic mass be capable of expanding under the pressure of the inflating medium, yet be of a reasonably viscous and coherent plastic character so as to be capable of supporting its own weight.

The inflating medium may be air or other gas which is non-reactive with the film-forming material or the packaged product. As heretofore mentioned, the inflating medium is preferably heated when delivered into the gob of film-forming material to prevent premature setting thereof. In sealing large containers or receptacles, it may be further desirable to effect sealing with the container itself being heated or disposed within a heated chamber. As more fully described hereafter, a gob of film-forming material may be partially inflated as a bu bble within the open end of a container, after which the container and bubble of film-forming material may be subjected to vacuum conditions. With this procedure, air and other gases may be removed from the packaged product concomitantly as the bubble itself expands into engagement with the adjacent container walls.

The teachings of the present invention are applicable to sealing containers of various types in which portions of the container itself are collapsed to effect closing. The containers may be formed of generally rigid or stiif materials in which preformed crease lines are provided to facilitate collapse of the open end of the container, as for example as in the case of conventional milk cartons, or may be made of flexible materials such as paper, fabrics, plastic films, regenerated cellulose, and the like. If desired, the material forming the container may be fluid-tight or may be lined to form a fluid-tight surface. For the sake of simplicity and ease of description, the method and apparatus of the present invention will hereafter be described as applied to the closing and sealing of conventional paper bags after the material or product to be packaged is disposed therein.

For a more detailed description of the invention, refercnce is initially made to FlGURES 1-3 of the drawing which illustrate a sequence of operations carried out in sealing a conventional paper container or bag 15 after the material or product to be packaged is disposed therein, as indicated by broken lines at 16. Initially, the container 15 is positioned with its open end directly below a nozzle 17 which includes a pair of spaced concentric or

telescoped tubes

19 and 21. The uppermost end of the tube 19 is connected to a supply of flowable film-forming material, with means being provided for periodically delivering the film-forming material. The tube 215. is similarly connected to a suitable pump or pressurized tank for delivering an inflating medium, such as air, in accordance with a predetermined flow pattern. Either the nozzle -17 or a support for the bag 15 Or both is mounted for vertical movement by suitable means, not shown, to facilitate desired positioning of the free end of the nozzle relative to the open end of the bag 15 at the start of operations.

In sealing the bag 15, the nozzle 17 is initially located in a desired position relative to the open end of the bag, after which plastic film-forming material is supplied through the tube 17 to form a gob thereof at the tip of the nozzle 17 where it covers the adjacent end of the tube 21, as shown by broken lines 23. The infiating medium is then supplied through the tube 21 to effect a continuous expansion of the gob of plastic filmforming material into the form of a bubble as shown at 25'. The position and the degree of inflation of the gob of film-forming material or size of the bubble 25 of film-forming material relative to the open end of he bag 15' may be varied to facilitate the application of the adhesive film-forming material to only desired areas of the bag walls, as more fully described hereafter.

Once a bubble of film-forming material of desired size is formed within the bag 15 a pair of tucker plates 27 are urged against opposite walls 29 of the bag 15 to pleat the same along preformed crease lines, as shown at 31. Concomitantly with this pleating operation, opposing walls 33 of the bag 15 are gradually moved toward each other by pressure plates 35 to ultimately close the bag. As the opposing walls 29 and 33 of the bag 15 are urged against the bubble 25, the inherent plastic or flexible character of the film-forming material and the compressible nature of the inflating medium permits the bubble 25 to be initially distorted into the gradually changing configuration of the open end of the bag 15. As best seen in FiGURE 2., during this distortion of the bubble 25, the film-forming material of the bubble wall gradually and progressively moves along and lines or coats the internal surfaces of the portions of the bag walls 29 and 33 with which it engages. The portions of the bubble wall 25 which are not engaged with the bag walls, such as the top and bottom portions of the bubble, are gradually stretched by the contained inflating medium as it is compressed during movement of the bag walls into closed position. Ultimately, these stretched portions of the bubble 25 are ruptured under the stresses imposed by the compressed inflating medium leaving an adhesive coating or lining of film-forming material on the internal surfaces of the bag walls 29 and 33 as shown at 37 in FIGURE 3. At this stage it is merely necessary to further urge the pressure plates 35 toward each other until the adhesively coated bag surfaces are snugly pressed together.

During rupture of the bubble 25, as described above, the portion of the film-forming material which remains attached to the nozzle 17 generally covers the open end thereof and thus prepares the nozzle of subsequent sealing operations. Alternatively, a wiper blade, not shown, may be urged across the free end of the nozzle 17 to remove any excess film-forming material attached thereto, after which film-forming material is again delivered through the tube 19 as heretofore described.

As heretofore mentioned, the surface areas of the bag walls 29 and 33 lined or coated with the adhesive filmforming material can be accurately controlled by the initial positioning of the free end of the nozzle 17 relative to the open end of the bag 15, and the degree of bubble inflation. in accordance with the above description, during the collapse of the open end of the bag 15, the wall of the bubble of film-forming material is distorted and progressively moves along and lines the internal surfaces of the bag walls with which it engages until bubble rupture occurs. Thus, with the free end of the nozzle 17 positioned slightly above or within the open end of the bag 15, the applied adhesive coating or lining of film-forming material generally extends to the uppermost edges of the bag walls. Alternatively, when the nozzle is projected well into the open end of the container, the adhesive lining of film-forming material applied to the internal surfaces of the bag walls terminates inwardly of the bag, leaving the internal bag surfaces directly adjacent to the uppermost edges or" the bag walls uncoated. It will, of course, be apparent that the width of this uncoated portion of the internal bag surfaces will vary with the extent to which the nozzle 17 is projected into the bag 15.

The degree of inflation of the gob of film-forming material relative to the size of the open end of the bag 15 primarily determines the area of the internal surfaces of the bag walls which are coated or lined with the adhesive film-forming material. Thus, where a relatively wide seal is required, the gob of film-forming material may be expanded until the resulting bubble 25 engages with and, if desired, progressively lines portions of the internal surfaces of the bag Walls 29 and 33. Alternatively, the mass of film-frming material may be expanded to form a bubble 25 which is smaller than the open end of the bag 15. With this latter procedure, the internal surfaces of the bag walls 29 and 33 would engage with the bubble 25 after the open end of the bag has been partially collapsed, or only during the terminal stage of the collapsing operation, to thus limit the area of the bag internal surfaces which engage with and are lined with the adhesive filmforming material before the bubble is ruptured.

The method of the present invention is not limited for use with specific bag or container constructions, or by the particular procedures employed in effecting collapse of the open ends of the various forms of containers. Thus, as shown in FIGURES 4 and a gob 41 of film-forming material carried by a nozzle 43 may be positioned adjacent to the open end of a filled bag 45 as it is supported by cooperating

grippers

47 and 49. In much the same manner as described with reference to FIGURES l-3, the gob 41 of film-forming material is expanded within the open end of the bag 45 as a bubble 51 of desired size. Relative movement is then initiated between the filled portion of the bag 45 and the

bag supporting grippers

47 and 49 to twist the bag at the area 53- within which the bubble 51 is located as shown in FIGURE 5. During this twisting operation, the bubble 51 is deformed and progressively lines or coats the internal surfaces of the bag until bubble rupture is occasioned. As heretofore described, the position and size of the bubble 51 relative to the open end of the bag 45 may be varied to control the area of the bag wall which is adhesively coated.

With relatively large containers or containers having elongated open ends, scaling is best achieved as shown in FIGURES -6 and 7. With the preferred procedure illustrated in FIGURE 6, a nozzle 55, similar to the nozzle 17 heretofore described, is positioned within or slightly above the open end of a container 57 and adjacent to one of its side walls 59. A gob of film-forming material is provided at the tip of the nozzle 55, in a manner as heretofore described, and is then expanded into a bubble 61. As the bubble 61 contacts with and adheres to the adjacent container wall 59, the nozzle 55' and container 57 are moved relative to each other concomitantly with the continued expansion of the film-forming material to provide a bubble 61 across the open end of the container. To assure that the wall thickness of the bubble is substantially the same along its entire length, the film-forming material is preferably delivered to the free end of the nozzle 55 at a uniform rate continuously with the expansion thereof. The open end of the container 57 may be then collapsed or 6 pleated and closed in the same manner as described with reference to FIGURES 1-3.

With the arrangement illustrated in FIGURE 7, a series of nozzles 63 are employed in providing a plurality of bubbles 65 01" film-fonming material Within the open end of a container 67. The nozzles 61 are similar to the nozzles 17 in construction and function, each including a duct 69 for delivering film-forming material from a common supply conduit 71, and a duct 73 for an expanding or inflating medium also supplied from a common conduit 75. Alternate nozzles '63 are preferably projected to at least two different levels within the open end of the container 67 to position the resulting bubbles 65 in staggered relationship. Thus, as the bubbles 65 are ruptured upon the collapse of the open end of the container full assurance is provided that all .desired interior surfaces of the container walls are lined with an unbroken coating of adhesive film-fonming material.

Added advantage of the present invention is that the method may be carried out under sub-atmospheric conditions. Thus, where it is desirable or necessary to remove air or other gases from the container and material being packaged, a gob of film-forming material may be partially inflated within the open end of a container while such container is positioned within a sealed chamber, after which the chamber may be evacuated. During the evacuation of the chamber, the partially inflated bubble of film-forming material gradually expands and covers the open end of the container. Final sealing could then be achieved as described with reference to FIGURES 1-3.

While preferred embodiments of the invention have been shown and described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A method of sealing an open-ended container after material to be packaged is inserted therein consisting of the steps of positioning a bubble of tacky film-forming material within an open end of the container above the material being packaged, collapsing a portion of the container adjacent to its open end against the bubble so as to rupture the same and cause the tacky film-forming material thereof to thereby provide a coating of tacky filmforming material along the internal surfaces of the collapsed portion of the container, and pressing the coated surfaces of the container together to bond the same.

2. A method as defined in claim 1 wherein the portion of the container adjacent to its open end is collapsed by twisting.

3. A method as defined in claim 1 wherein the portion of the container adjacent to its open end is collapsed by urging opposite walls thereof toward each other.

4. A method of sealing an open-ended container after material to be packaged is inserted therein consisting of the steps of positioning a bubble of tacky film-forming material within the open end of the container above the material being packaged, gradually collapsing the portion of the container adjacent to its open end to progressively engage the internal surfaces of such portion of the container with the bubble of tacky film-forming material, continuing the collapse of said container portion until the bubble of tacky film-forming material is ruptured to cause the tacky film-forming material thereof to thereby provide an adhesive coating along the internal surfaces of the collapsed portion of the container and pressing the coated surfaces of the container together to bond the same.

5. A method of sealing an open-ended container after material to be packaged is inserted therein consisting of the steps of positioning a mass of tacky film-forming material Within the open end of the container above the material being packaged, expanding the mass of material into the form of bubble which engages with the internal surfaces of that portion of the container adjacent to its open end, and collapsing the portion of the container engaged with the bubble so as to rupture the same and cause the tacky film-forming material thereof to thereby provide a coating of tacky film-forming material along the internal surfaces of the collapsed portion of the container, and pressing the coated surfaces of the container into contacting relationship with each other.

6. A method as defined in claim wherein expansion of the mass of material is effected by partially inflating the same and subsequently applying a vacuum to the open end of the container and the partially inflated mass of material.

7. A method as defined in claim 5 wherein the portion of the container adjacent to its open end is collapsed by twisting.

8. A method of sealing a container having an open end of elongated configuration after material to be packaged is inserted therein consisting of the steps of disposing a mass of tacky film-forming material within the open end of the container above the material being packaged, expanding the mass of tacky film-forming material into the form of a bubble, continuously delivering tacky fihnforming material to the mass during the expansion thereof, effecting movement of the mass of tacky film-forming material relative to and along the open end of the container concomitantly with the expansion thereof, collapsing the portion of the container adjacent to its open end against the bubble so as to rupture the same and cause the tacky film-forming material thereof to thereby provide a coating of tacky film-forming material along the internal surfaces of the collapsed portion of the container, and engaging the coated container surfaces to adhesively bond the same.

References Cited in the file of this patent UNITED STATES PATENTS 1,422,300 Pape July 11, 1922 2,252,435 Lust Aug. 12, 1941 2,313,643 Howard Mar. 9, 1943 2,412,862 Bergstein Dec. 17, 1946 2,532,871 Wagner Dec. 5, 1950 2,585,766 Guggenheim Feb. 12, 1952 2,592,081 Toulmin Apr. 8, 1952 2,833,096 Randall May 6, 1958 2,872,766 Meissner Feb. 10, 1959 2,903,833 Jones Sept. 15, 1959 2,907,153 Toles Oct. 6, 1959 2,962,843 Hoelzer et a1 Dec. 6, 1960 2,996,858 Swenson Aug. 22, 1961 3,037,897 Pelley June 5, 1962

Claims

8. A METHOD OF SEALING A CONTAINER HAVING AN OPEN END OF ELONGATED CONFIGURATION AFTER MATERIAL TO BE PACKAGED IS INSERTED THEREIN CONSISTING OF THE STEPS OF DISPOSING A MASS OF TACKY FILM-FORMING MATERIAL WITHIN THE OPEN END OF THE CONTAINER ABOVE THE MATERIAL BEING PACKAGED, EXPANDING THE MASS OF TACKY FILM-FORMING MATERIAL INTO THE FORM OF A BUBBLE, CONTINUOUSLY DELIVERING TACKY FILMFORMING MATERIAL TO THE MASS DURING THE EXPANSION THEREOF, EFFECTING MOVEMENT OF THE MASS OF TACKY FILM-FORMING MATERIAL RELATIVE TO AND ALONG THE OPEN END OF THE CONTAINER CONCOMITANTLY WITH THE EXPANSION THEREOF, COLLAPSING THE PORTION OF THE CONTAINER ADJACENT TO ITS OPEN END AGAINST THE BUBBLES SO AS TO RUPTURE THE SAME AND CAUSE THE TACKY FILM-FORMING MATERIAL THEREOF TO THEREBY PROVIDE A COATING OF TACKY FILM-FORMING MATERIAL ALONG THE INTERNAL SURFACES OF THE COLLAPSED PORTION OF THE CONTAINER, AND ENGAGING THE COATED CONTAINER SURFACES TO ADHESIVELY BOND THE SAME.