JPH06122427A - Method and device to wrap article densely by using synthetic film - Google Patents

Abstract

PURPOSE: To tightly wrap a deformable thin two-dimensional article or three- dimensional article with high sealability by wrapping a surface of an article with a sheet of a shrink film, heating overlapping portions at both ends of the sheet, and keeping a temperature of the heated portion of the sheet below a melting point of the film. CONSTITUTION: Two rotary cylinders 1, 1' are heated by an internal heating means. Then the rotary cylinders 1, 1' are rotated to move an article 2. Simultaneously the article 2 is heated and pressed. That is, the self-sealing action of the overlapping portion 5 and the shrinkage of the shrink film, that is, the shrinkage and the sealing can be simultaneously executed. When the article 2 is a three-dimensional one, the cylinders 3, 3' are mounted and contacted with a side surface of the article 2 for heating the same. Whereby the film covering the most part of a surface of the article 2 can be shrinked. Accordingly, the film can be optionally provided with an additional heating surface on the basis of a type of the article to be wrapped according to the necessity, and this method can be applied to any shape.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method and apparatus for tightly wrapping articles with synthetic films. More specifically, the present invention relates to the use of shrinkable films for packaging, label attachment, and similar purposes.

[0002]

The use of paper or plastic film for labeling purposes and for wrapping articles is a known technique. For example, polystyrene, polypropylene, and PVC films are used as label materials for bottles.

Further, shrinkable or non-shrinkable films of PVC and polyethylene are commonly used to wrap both essentially two-dimensional and three-dimensional articles such as magazines. However, the use of these films is very limited for the following reasons. When wrapping a two-dimensional object in essence, shrinking will deform a thin article, so shrinking is not allowed to produce a significant amount of shrinkage. Further, sealing of the overlapping portions of the film is accomplished by various techniques such as ionization, high voltage, and heat sealing. Some of them require melting the film along the lines of superposition. In these techniques, the connection portion is weakened and the material is not welded uniformly, so that the appearance is not good. On the other hand, three-dimensional or rigid objects can usually withstand relatively high contraction forces. So a shrinkable film can be used.
However, the resulting packaging is not independent of the need for welding along the overlapping portions of the packaging.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus in which a shrinkable film having a sticking and shrinking action can be used as a label material for a deformable container. Another object of the present invention is to provide a method and apparatus for wrapping an essentially deformable, thin two-dimensional object with a shrinkable film and wrapping it tightly without deformation. Another object of the present invention is to provide a method and apparatus in which the connection of overlapping portions of the film for covering can help produce a covering of good appearance and strength. Another object of the present invention is to provide a method and apparatus that can provide excellent sealing of the overlapping portions of the film for covering.

The films used with the method and apparatus of the present invention must have certain properties. It will become apparent with the description herein. It will also be apparent to those skilled in the art. For example, the film used to label a deformable container, such as a PET bottle, must have a relatively low shrink force. And, although it preferably has good adhesion properties, adhesion when wrapped is undesirable. An example of this is a sheet of paper. Suitable shrinkable films are described, for example, in the corresponding Israeli patent application No. 92868 filed December 25, 1989 by the same applicant. This specification is incorporated herein by reference. Also, it is preferable that the shrinkage force is low when wrapping a deformable article, and if the article is essentially non-deformable, the shrinkage force may be high, so it is important to control the shrinkage force of the film. Is.

[0006] As mentioned above, when the article is covered, either labeled or fully wrapped, a sheet of film is provided. Care is then taken to overlap the ends of the film to some extent to provide what is hereinafter referred to as the "overlap region". When the overlapping area is sealed according to methods known in the art, only the narrow width of this area is welded. And most of the overlapping areas are not connected. Of course, the two layers that remain separated by it are not very strong bonds. Furthermore, as described above, the line obtained by welding for sealing between the two layers forming the overlapping region has a poor appearance and is optically
The characteristics are unsatisfactory in terms of sealability and strength. Now, surprisingly, the "self-sealing effect" of the film since then
What is called a layer is formed by integrating one layer with the other to provide a region that retains its excellent appearance and optical properties, which together form a very strong bond. It has been discovered that there can be a seal between the two layers of the overlap region, as is done, and that this can be done by using a temperature below the melting temperature of the film. All of these advantages are obtained with the method of the invention, which is detailed below.

[0007]

A method for densely wrapping an article or a portion thereof with a film is: A, supplying a shrinkable film, B, using a sheet of the shrinkable film. Wrapping the surface of the article by at least partially overlapping at least both ends of the sheet, C, applying heat to at least the overlapping portion of the sheet,
Keeping the temperature of the heated portion of the sheet below the melting point of the film. Preferably, heat is applied with pressure in order to obtain an effective self-sealing effect of the film. Heat may be applied by a variety of techniques, the preferred techniques being contact heat exchange, forced convection, radiation. When it is desired to use a film with adhesive properties, such as in the case of label attachment, it may be desirable to heat the surface of the object to be wrapped before covering with the shrinkable film. This often improves the adhesion of the film to the article surface. Adhesive films, such as those described in Israel Patent Application No. 92868, have excellent self-adhesive properties such that the ends of the sheet adhere to each other so that the overlapping areas are formed very easily. It should be noted that However, it should be noted that heating the contact surfaces temporarily improves the adhesion of the film, similar to that obtained by ionization techniques. However, the sealing action of the overlapping areas must provide a durable connection.

Thus, another aspect of the invention consists essentially of a method for attaching a label to a tubular article.
The method comprises providing a label made of a film as previously defined, wrapping the label around a tubular object, and heating the label at least in the overlap area, its self-sealing action and the label. To get the shrinkability of. Of course, label shrinkability is desirable to ensure retention on the article, as those skilled in the art will appreciate. Again, pressure can be applied to the overlapping area to improve the self-sealing effect. This is particularly convenient when the item to be labeled is a bottle or a can of food or beverage, especially when they are made of a deformable material such as PET, because the force of shrinkage can be controlled. is there. In another aspect of the invention, a method for wrapping an essentially two-dimensional object is provided. The method comprises providing a sheet made of a film as defined above, covering an object with an overlapping area therein, heat sealing the open end of the sheet, and its self-sealing action. To achieve and, optionally, to achieve shrinkage of the shroud, at least the overlap region is pressure heated.

As will be apparent to those skilled in the art, sufficient hold time and temperature must be provided to achieve satisfactory results. However, it has been discovered that excellent results are obtained when the article passes through two successive sealing steps. While not wishing to be bound by any particular theory, a heating cycle consisting of a heating-cooling-heating-cooling sequence is more likely than that obtained when applying the same amount of heat for the same amount of time in one step. It may be responsible for the improvement, especially the appearance of the final packaging. Yet another aspect of the invention provides a method for wrapping a three-dimensional object. The method is to provide a sheet made of a film as defined above, to cover an object and to provide a lap area therein, to heat seal the open end of the sheet, to wrap the film to shrink it. It consists of pressurizing and heating the surface of the object on which the mating area is located, and heating one or more of the remaining surfaces of the object. Heating to shrink the film can be accomplished by various methods such as contact or convection or radiant heating.
Alternatively, it can be performed by a combination of two or more of the above heating methods.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the device comprises two rotating cylinders 1 and 1 '. These cylinders are heated by internal heating means or other suitable means. Then, they rotate and move the object, shown schematically as 2. At the same time heat it and apply pressure. Doing this gives two types of results. The self-sealing action of the overlapping area and the shrinkage of the shrinkable film. It should be noted that it is a new feature of the present invention that the shrinking and the sealing are performed simultaneously. Prior art devices perform sealing one technique at a time, with some time delay and deflation in completely different ways. So, as will be apparent to those skilled in the art, the method of the present invention not only yields better results, but is also more convenient and economical. Providing two or more sets 1 and 1'of the above cylinders in series,
Different heating cycles may be performed. The cylinder itself may be made of various materials such as stainless steel, silicon, etc., or may be coated. A skilled technician can prepare appropriate constituent materials for desired heating conditions. If the article 2 is essentially three-dimensional, it is possible to provide the cylinders 3 and 3'shown in distant position in FIG. The two cylinders 3 and 3 ′ are brought into contact with the side surface of the article 2. Then, heat again. This contributes to shrinking the film covering the article 2 over most of its surface. The cylinders 3 and 3'may contact the article 2 at the same time as the cylinders 1 and 1 '. Alternatively, it may be located some distance from it and act separately.

Turning now to FIG. 2, FIG. 2 (a) is a front view of an article sealed by the technique illustrated by FIG. This article has both open ends 4 and 4'caused by wrapping the sheet material around the article. The open end can be closed by known techniques such as hot cutting or similar techniques. The overlapping area 5 is clearly shown in the figure. This area is created by covering the article with a sheet. In FIG. 2 (b), this area after the self-sealing action has been shown as the location indicated by numeral 6 with a slightly thicker cross section. Although its cross section is thicker than the film in other locations, the overall appearance of the overlapping area after self-sealing is about the same, and it is often difficult to locate this area. . The self-sealing effect according to the invention, in contrast to the weakened area of the overlapped area sealed according to the prior art, is actually greater in areas thicker than the film in other locations around the object. It should also be noted that it is getting stronger. This is also shown in FIG. In FIG. 3, the overlapping area, indicated generally as 7, is sealed by known techniques to give two tongue-shaped free ends 8 and 8 '. They are connected by welding made only along a narrow band shown as 9 in the figure. It is preferable to have some small openings in the film to allow air to escape during the pressure seal, as the film will be completely sealed. This is achieved, for example, by placing a toothed wheel or similar device on the packaging device, which contacts the film before the article reaches the area of pressure, creating a small opening in the film. To be done. If no such opening is provided, the outflow of air will occur at uncontrolled locations during the pressure seal. Although this still yields a generally acceptable product, it is desirable to be able to control the position, size and number of openings present in the film.

FIG. 4 shows a conveyor, instead of a rotating cylinder.
Figure 6 shows another configuration using a belt or ribbon. In this figure, two conveyor belts 10 and 10 'are shown. They may both be heated, for example by plates 11 and 11 'which heat the belts with radiant heat, or it is possible to heat only one of the two belts. The belt can be rotated in various directions to place the tubular object, such as the tubular object 12 schematically shown in FIG. Furthermore, if the tubular object is a cylinder or the like, leave an extra width at the end of the film and shrink it by heating, for example by radiation or forced convection, to hold the end of the cylinder firmly. Good. In such a case, after the film has shrunk on both ends, it has the appearance 12 shown in FIG. 4, with a hole in the center, but the film shrinks along the outer surface of the cylinder end. A cross section of another possible structure is shown schematically in FIG. In this figure, the cross section of the belt shown is matched to the shape of the article to be labeled, in this case the bottle. Thus, the label 13 (shown in phantom in the figure) is heated by the belt 14 having the same shape and being heated, and the label changes at the position where the diameter of the bottle changes, for example, at the positions indicated by 15 and 16. Is contracted. This provides a strong hold of the label on the bottle.

A label applying device according to another preferred embodiment of the present invention is shown schematically in FIG. The device comprises a continuous lower conveyor belt 17, a first upper conveyor belt 18 and a second upper conveyor belt 19. The bottle 20 in the apparatus moves in the direction of the arrow by the movement of the belts 17 and 18. If desired, the bottle can be preheated by the heating element 21. A continuous label applicator (not shown) is provided with label material 22 from label roll 23 via scissor roll 24.
To supply. The label is guided towards the bottle 20 by means known to the skilled technician and not shown for simplicity. And wrap around it. The continuous label 22 is then provided by known means (not shown) to the bottle 2
It is cut at an appropriate time at a position between 0 and the scissors roll 24. The label-wrapped bottle is further moved by the combined action of conveyor belts 17 and 19. It is then heated by the heating element 21 ′ of the belt 17 and / or the belt 25 of the belt 19 while rotating.

All of the above description of the preferred embodiments of the present invention has been presented for purposes of illustration only and should not be construed as limiting. Many modifications will be apparent to those skilled in the art that the method and apparatus of the present invention can be made. For example, various shaped heating surfaces such as cylinders and belts may be provided. Then, heat may be applied by various methods, and pressure may be applied as necessary. Also, various shaped devices, types of objects to be packaged, and films can all be used without departing from the scope of the invention.

[Brief description of drawings]

1 is a schematic diagram of a sealing device according to a preferred embodiment of the present invention.

2 shows an essentially two-dimensional article, such as a sheet of paper, wrapped according to FIG. 1 according to the invention.

FIG. 3 shows the same article as in FIG. 2 but packaged in a prior art method.

FIG. 4 is a diagram showing an apparatus for covering a cylindrical object.

FIG. 5 shows an apparatus for partially covering an object whose ends are no longer cylindrical.

FIG. 6 is a view showing a label attaching device according to another embodiment of the present invention.

[Explanation of symbols]

 1, 1 '... Cylinder 2 ... Article 3, 3' ... Cylinder 4, 4 '... Open end 10, 10' ... Conveyor belt 12 ... Cylindrical object

Claims (18)

[Claims] 1. A method for sealing an article or a part thereof with a film and tightly wrapping by shrinking, A, supplying a shrinkable film, B, one surface of the shrinkable film And at least partially overlapping at least both ends of said sheet, C, applying heat to at least the overlapping area of said sheet,
The temperature of the heated portion of the sheet is kept below the melting point of the film. 2. The method of claim 1, wherein the heat is applied by catalytic heat exchange. 3. The method of claim 1, wherein the heat is applied by forced convection. 4. The method of claim 1, wherein the heat is applied by radiation. 5. The method according to claim 2, further comprising applying pressure to at least the superposition region. 6. The object to be wrapped is further heated before adding the shrinkable film to improve the adhesion of the film to the surface of the object. the method of. 7. Providing a label made of a film as claimed in claim 1, essentially for labeling a tubular object, wrapping the label around the tubular object. And heating the label, at least in the overlap region, to achieve its self-sealing action and to shrink the label. 8. The method of claim 7, further comprising applying pressure to the overlap region. 9. Process according to claim 7 or 8, characterized in that the essentially cylindrical object is a container, in particular a bottle or a can of food or beverage. 10. Providing a sheet made of a film as described in claim 1, covering an essentially two-dimensional object and providing an overlapping area therein, An essentially two-dimensional object consisting of heat-sealing the open end and pressurizing at least the overlapping area to achieve its self-sealing action and to selectively shrink the shroud. How to wrap. 11. Providing a sheet made of a film as claimed in claim 1, enclosing an essentially three-dimensional object and providing an overlapping area therein, Three-dimensional consisting of heat-sealing the open end and pressurizing the surface of the object on which the overlapping area is located and shrinking one or more remaining surfaces of the object to shrink the film. To wrap other objects. 12. Pressure heating is carried out in at least two stages, the surface of the object to be pressure heated being able to be at least partially cooled between two subsequent pressure heating stages. The method according to claim 10 or 11, which comprises: 13. Method according to claim 11 or 12, characterized in that the heating for shrinking the film is carried out by heating by contact, convection or radiation, or by a combination of two or more heating methods. 14. The method according to claim 1, wherein the shrinkable film is a film that acts to adhere and shrink. 15. Two or more transport and pressure elements for transporting an article to be covered through an apparatus and for exerting pressure and heat thereon, said transport and pressure element comprising: An apparatus, comprising at least one provided with or in combination with a heating element, for sealing an article or a part thereof with a film and tightly covering by shrinking. 16. Apparatus according to claim 15, characterized in that the conveying and pressing elements comprise rotating cylinders. 17. The transport and pressure element comprises a conveyor belt or ribbon.
The described device. 18. The apparatus of claim 17, wherein the conveyor belt has a cross section that essentially corresponds to the shape of the surface to be covered by the film.