US3471351A

US3471351A - Method and apparatus for producing a packaging material having strip on one side and covering tapes on the other side

Info

Publication number: US3471351A
Application number: US584904A
Authority: US
Inventors: Alfred Fuchs
Original assignee: Tetra Pak AB
Current assignee: Tetra Pak AB
Priority date: 1966-04-12
Filing date: 1966-10-06
Publication date: 1969-10-07
Anticipated expiration: 1986-10-07
Also published as: SE314578B; GB1149545A; CY514A

Description

Oct. 7, 1969 A. FUCHS 3,471,351

' METHOD AND APPARATUS PRODUCING A PACKAGING MATERIAL HAVING RIP 0N om: swan/mu COVERING TAPES on THE OTHER SIDE Filed Oct. 6, 1966 2 Sheets-Sheet 1 Fig.1

INVENTOR A L F R E D F U C H 8 ATTORNEY Oct. 7, 1969 ue s METHOD AND APPARATUS FOR PRODUCING A PACKAGING MATERIAL HAVING STRIP on ONE SIDE AND COVERING TAPES ON THE OTHER SIDE 2 Sheets-Sheet 2 Filed 001;. 6. 1966 Fig.3

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INVENTOR A L FRE D F U C HS ATTORNEY United States Patent 3,471,351 METHOD AND APPARATUS FOR PRODUCING A PACKAGING MATERIAL HAVING STRIP ON ONE SIDE AND COVERING TAPES ON THE OTHER SIDE Alfred Fuchs, Lund, Sweden, assignor to AB Tetra Pak,

Lund, Sweden, a Swedish company Filed Oct. 6, 1966, Ser. No. 584,904 Claims priority, application Sweden, Apr. 12, 1966, 4,881/66 Int. Cl. 1532b 31/10 U.S. Cl. 156252 9 Claims ABSTRACT OF THE DISCLOSURE The method and apparatus for making packaging material with pull tab openings is disclosed in which first a hole is punched in the web then a tab is applied over the holes on one side of the web and a continuous strip is applied to the other side.

This invention refers to a web-shaped packaging material of paper, plastic, cardboard or the like, which has been provided with apertures entirely penetrating the material, the apertures being intended to form access openings in the finished packages, said apertures further being covered by removable tapes or wafers on the side of the material intended to define the outside of the packages.

There are known in the art, i.e. by the US. Patent No. 3,166,226, packages of the kind having an aperture punched in the wall, the aperture being covered by a tape sealed to the container wall around the aperture. The difliculties of, in the case when the packaging material comprises a fibrous carrier layer, providing access means that are not susceptible to leakage have been paid attention to inter alia in the said patent. The solution suggested in the patent for preventing liquid from being sucked up in the fibrous layer, comprises the step of heat sealing the tape to the region of the aperture, which causes some of a polyethylene lamina of the tape to penetrate into the outer portion of the paper lamina of the web-material so that the polyethylene is infused around the fibres thereby impregnating the cut surfaces of the aperture. Though the method has great merits, it cannot, however, be considered sufliciently safe for the use in producing sterile packages, while in this case the tightness of the packages unconditionally must be guaranteed. In this connection it should be noticed that such packages which are not leaking in the normal sense of the word but which in any region have their walls wet through, from a bacteriological point of view are considered as leaky.

One solution of the problem is given in the US. Patent No. 2,870,935, in which is shown a can with an opening and an outer cover and an inner seal united with the outer cover and being able to be removed to obtain access to the contents of the container.

An analogous solution is also shown in the Swedish Patent No. 194,525. According to this patent the inner seal consists of a piece of a sheet material which is thin compared with the outer cover. Preferably the inner sheet consists of a thin plastic material, which easily might be torn as it is well united with the outer cover. However, pieces of a thin sheet material are difiicult to work with, which constitutes a drawback of the method. One object of the present invention therefor is to eliminate this drawback by a covering method which is in line with a continuous way of working.

Thus the material according to the present invention is characterized therein that a continuous strip of a tearable material covering the apertures is applied to the other side 3,471,351 Patented Oct. 7, 1969 of the packaging material, the strip being aflixed on one hand to the material around and between the apertures, and on the other hand to those portions of the outer tapes which are accessible through the apertures.

The invention also aims at a method for producing the material characterized in that the strip together with the web material under compression and active uniting are being brought between a pressure-roller and a counter action means, the strip being fed between the pressure-roller and that surface of the web material which is intended to define the inside of the finished containers, the strip being brought to the apertures and to be affixed on one hand to the packaging material around and between the apertures and on the other hand to portions of the outer tapes accessible through the apertures. The necessary adhesion between the inner strip, the web material and the outer tape, is provided preferably therein that the web material and the tape are coated with a thermoplastic layer on the side turned to the strip, and in that the web material together with its tapes is heated immediately prior to its being brought into contact with the strip. Of course it is also possible instead or in addition to activate the strip to an adhesive state, the strip preferably consisting of a thin thermoplastic material. One can also provide the strip with special glues.

When developing a device for carrying out the method there was first suggested to provide a pressure roller made of soft rubber hoping that the roller might be able to bring the thin inner strip into a good contact with the outer tape. The method might be said to constitute a transfer of the principles shown in the US. Patent No. 2,646,105 to a continuous way of operation. However, the result did not turn out to become the desired and the method also has other drawbacks. Thus, instead of a strong seal between the outer tape and the inner strip within the main portion of the area of the aperture, there was obtained only a rather bad seal between the two members within a region of the centre of the aperture. Further the soft pressure roller proved very soon to be worn-out.

These drawbacks, however, are eliminated by utilizing a new device thereafter developed and which is characterized therein that the pressure roller is knurled and is made of a rather hard material. Thanks to this in itself rather simple design a number of advantages are gained. The hard wear disappears by choosing a non-soft material that has other desirable features. That plastic material which is for sale under the trademark Teflon has proved to be suitable. Thanks to the roller being knurled considerable surface pressures are obtained in the regions of the apexes of the knurl-pattern so that the web material within these regions strongly might be compressed. By the fact that the thickness of the web material thus in certain regions, inter alia in the region of aperture edges, might be reduced and under influence of the radius of the roller good seals have been obtained between the tapes and the inner strip also in the peripheral portions of the discharge openings. In the case when the knurl has been given the shape of a cross-pattern, the seals will receive the shape of a regular pattern of dots. One has noted that a seal which has been made by means of such a device satisfies all demands as to its tightness. Further, at the same seal a piece of the inner strip substantially corresponding to the size of the aperture punched in the web material will certainly be removed when tearing off the outer tape.

The invention will now be more closely described with reference to the attached drawings, in which FIGURE 1 shows a tetrahedron shaped package which is provided with a tape covering a discharge opening punched in the package wall;

FIGURE 2 schematically illustrates how the discharge openings on that side of the package material which is intended to define the inside of the finished containers, are being covered with an inner tightening strip;

FIGURE 3 is a section IIIIII in FIGURE 2 in a large scale;

FIGURE 4 schematically, in a large scale shows a seal obtained according to a method first suggested during the development of the present invention; and

FIGURE 5 shows a seal obtained by means of a preferred embodiment of the device according to the invention.

The package chosen by way of example and to which the principles of the invention are intended to be applied consists, as is apparent from FIGURE 1, of a tetrahedronshaped container of a well-known kind. The package has in a way known in the art been made of a webshaped packaging material, which by special means has been formed into a tube. The tube having been longitudinally sealed, filled up to a certain level with a filling material, sealed and severed in sealing zones transverse to the tube axis. The invention has been developed for the use in an aseptic machine, i.e. a machine which under aseptic conditions fills sterile package containers with a sterile filling material. At these machines the web material is sterilized prior to its being fed into the sterile machine. Preferably the web material is sterilized therein that it is fed through a sterilizing bath as will be shown in the following.

The packaging container shown in FIGURE 1 has in a well-known manner been provided with transverse seal fins TF and a longitudinal seam LS. Positioned in one of the four corners of the container there is a discharge opening 1 punched in the package wall. The discharge opening is exteriorly covered by a tape 2 sealed to the portion of the wall surrounding the opening. An end portion 2a of the tape is unsealed to the container to provide a pull-tab for removing the tape when access to the contents of the container is desired. Interiorly the container is further provided with a strip of a thin thermoplastic material. The strip has been indicated by dash lines in the figure and designated 3. Further, the strip has been sealed to the tape 2 in the region of the aperture 1 in a manner which will be more closely described with reference to the following, so that when the tape is torn away a piece of the inner strip will be removed whereby a passage through the aperture is established.

In FIGURE 2 a process for the manufacturing the packaging material is schematically illustrated. Herein 4 refers to a web-shaped packaging material which at a projected machine is intended to consist of a paper which on the side intended to define the inside of the packages has been provided with a plastic coating. Prefer-ably the material also comprises an aluminum lamina. However, also other materials are possible, e.g. two-side-plasticcoated materials. The present invention, however, has its greatest importance for such materials which for economical or other reasons have been provided with a plastic coating only on one side.

The web material is continuously or intermittently unwound from a supply roll 5; guided over conducting rollers 6, 7 and 8; through a sterilizer 9 in which the plastic coated surface is treated with a sterilizing agent; and into a sterile chamber 10 in which the sterile material is formed into a tube which in a well-known manner under aseptic conditions is filled and separated into closed packages,

Between hte conducting rollers 6 and 7 aperture 1 are punched by means of a puncher 11 penetrating the material 4, the apertures being covered by tapes 2. The tapes preferably consist of plastic strips or plastic coated paper strips which prior to their being applied are heated, so that they when being mounted will adhere to the web material.

By means of heating coils 12 the plastic coated surface of the web material 4 is heated to such an extent that the plastic lamina of the web material 4 and the portions of the tapes defined by the apertures 1 will be adhesive. A strip 3 consisting of a thin thermoplastic material, e.g. polyethylene, is unwound from a supply roll 13. The strip 3 is guided between a cross-knurled pressureroller 14 and the web material 4 by being driven by the web material which is pulled upward between the pressure roller 14 and a counter action roller 15. The two rollers are supported in bearings and are rotated by the web material 4. Further, they are forced against each other thereby compressing the web material 4; the strip 3; and the tapes 2, so that the strip 3 is united with the soft made plastic coating. Due to the fact that the pressure roller 14 is made of the soft material called Teflon damages in the thin strip 3 are avoided. By the choice of material one also prevents from adherence between the pressure roller 14 and the soft made plastic coating. The counter action roller 15 is preferably made of a soft rubber.

In FIGURE 3 is more closely illustrated how the uniting of the inner strip 3 and the outer tape 2 is carried out. At a projected apparatus the two

rollers

14 and 15 are given equal radiuses R=14 mm. and equal axial lengths of 28 mm. The counter action roller 15 is as mentioned made of a rather soft rubber material and the pressure roller 14 is made of Teflon and is crossknurled. The cuts have been made to a depth of 0.6 mm. whereupon the apexes have been smoothed off one or a few tenths of a millimetre. Compared to this might be mentioned that the paper qualities (the packaging material 4) for which the apparatus is intended to be used have a thickness of 0.15 to 0.30 mm. In the region of the access openings the thickness is increased to substantially twice as much due to the tapes 2. The inner strip 3 has a breadth of about 10 mm. and a thickness of 0.05 mm.

Due to the fact that the pressure roller 14 is knurled and by a suitable choice of the radius R very high surface pressures are obtained in the regions of the apexes of the knurl pattern. A strong compression of the packaging material thus is obtained within these well-defined areas. Because of dimensional circumstances these substantially dot-shaped regions of compression are very diflicult to set forth in a vertical section as in FIGURE 3. Instead there is referred to FIGURE 5 in which is shown a typical sealing pattern obtained by means of the device accordmg to the invention. The sealing has been carried out 1n a number of small rhombidic areas corresponding to the apexes of the knurled pattem. As the roller 14 runs over the aperture 1 the knurled apexes force the strip 3 against the tape 2 so that the adhesive-activated tape and the strip are permanently united. In FIGURE 3 a knurled apex in turn to force a piece of the strip 3 into the aperture 1 into contact with the tape 2 has been designated 16.

As a comparison there is in FIGURE 4 shown a seal obtained by means of the device which was first proposed during the development of the present invention, i.e. a device wherein the pressure roller consists of a flexible rubber roller. Due to the fact that one in this case cannot obtain as high surface pressures as when utilizing a firm knurled roller the thickness of the packaging material will have an essential influence upon the result. Contact between the inner strip 3 and the outer tape 2 thus only will occur within a rather small portion of the aperture 1. Further it is not only desirable that the two materials are brought into contact with each other but far rather that they are firmly compressed within the contact regions.

It should be apparent that the invention is not limited by the described embodiment of the invention but only of the attached claims. As possible modifications i.e. might be mentioned that the apertures 1 need not have the shown circular shape. For certain purposes it might instead be more suitable to provide the packaging material with slot-shaped apertures. In this case it might be more advantageous to give the pressure roller a simple knurled-pattern. The applications of the invention of course are not restricted to tetrahedron-shaped packages. Also modifications of the counter-action means as well as of other members of course are possible to carry out without departing from the spirit and scope of the invention.

That which is claimed is:

1. A method of producing web shaped packaging material with pull tab openings therein comprising the steps of: supplying a web of packaging material, creating a series of openings therein, sealing a tab over each opening on one side of said web of material, supplying a con tinuous strip of material to the other side of said web of material over said apertures, and sealing said continuous strip of material to said other side of said web material and to that portion of said tab over said aperture which is accessible through said opening.

2. The method of claim 1 wherein said continuous strip of material is pressure sealed to said web material.

3. The method of claim 2 wherein said heat is supplied to the surface of said other side of said web material prior to pressure sealing of the continuous strip of material thereon.

4. The method of claim 3 wherein the surfaces of said continuous strip of material and the Web material sealed together is thermoplastic.

5. Apparatus to form a web material with sealed openings therein comprising: means to supply a moving web of packaging materials, means to provide a plurality of spaced openings in said materials, means to seal a pull tab over each of said openings on one side of said web material, means supplying a continuous strip of sealant material to the other side of said web material and means to seal said continuous strip of sealant material to said other side of said Web material, to a portion of said pull tab accessible through said apertures and to the edges of said apertures.

6. The apparatus of claim 5 wherein said means to seal said sealant material includes a pressure roller and a counter action means.

7. The apparatus of claim 6 wherein said pressure roller has a knurled surface.

8. The apparatus of claim 7 wherein said counter action means is a roller.

9. The apparatus of claim 5 wherein the surfaces of said web material and said continuous sealant strip facing each other are thermoplastic and means are provided to heat the thermoplastic surface of said web material prior to sealing to said continuous strip.

References Cited UNITED STATES PATENTS 2,899,347 8/1959 Kindseth 156-252 3,336,845 8/1967 Lepisto et al 156-514 3,361,611 1/1968 Stark 156252 DOUGLAS J. DRUMMOND, Primary Examiner US. Cl. X.R. 156-514, 583