DE2149414A1 - Vacuum packaging process and device suitable for it - Google Patents

Description

Vacuum packaging method and device suitable for this

The present invention relates to a vacuum packaging method for food. and other packaging goods. Here and in the following, vacuum means in its general sense Form that there is a pressure differential of either gaseous or liquid fluid.

In the so-called "skin" packaging process, which is included in the is essentially a vacuum forming process, a section of thermoplastic film is held by a frame and underneath the frame is a vacuum plate on which the packaging pad is arranged. The goods to be packaged is placed on the base and the thermoplastic film is heated in the frame. If the film is soft enough, so the frame is lowered, whereby the plastic film lays itself over the product. This creates a partial vacuum generated by the vacuum plate and the air under the plastic

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film pulled off through the packing underlay. Because of the pressure difference The air between the top and the bottom of the plastic film is pressed tightly around the product. The foil or the packaging underlay can be coated with an adhesive be, so that a strong adhesion is achieved when the film and the substrate come into contact, resulting in a package in which the Is held firmly to the base and transported safely and later stacked and strung in a pleasing manner at the retailer or can be offered hung.

In the vacuum "Skin" -Verpackungsverfahren is used in contrast to the above described "Skin" -Verpackungsverfahren not only a gas-impermeable plastic film but also a gas impermeable \ ^/ 'erpackungsunterlage, the package obtained, if desired, evacuated and hermetically sealed can be. The aim is to achieve the same effect, ie the product should be held firmly to the packaging substrate by the transparent film. One common method is to use a porous or perforated packaging pad so that the vacuum can be applied directly to the packaging pad. In the vacuum skin ^{ll M} -Verpackungsverfahren generally a vacuum chamber is used having an open top. That

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Packaged goods located on an impermeable packaging substrate are placed inside the vacuum chamber on a Countertop laid; then the open chamber is then covered with the film, which is firmly attached to the chamber and forms a vacuum-tight seal. The chamber is evacuated while the film is on its deformation and Softening temperature is heated. Then the worktop is raised and drives the packaged goods or into the softened film, using compressed air from above to press the film firmly around the material. One such procedure is for example described in French patent specification 1,258,357.

In an improved method of this type according to French patent specification 1,286,018, after evacuation the Chamber and after pressing the packaged goods against the hot, soft film, the vacuum is lifted and outside air let into the chamber so that the thermoplastic film more or less conforms to the product because it is on the side of the film facing the packaged goods has formed a vacuum, while on the other side of the film it is more normal Air pressure prevails.

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From Australian patent specification 245,774 there is a vacuum "skin" packaging method known, in which the goods to be packaged are used in the lower half of a vacuum chamber on a base is followed by a thermoplastic film over the open side of the lower. Half of the chamber placed, the chamber closed and both chamber halves are brought to essentially the same vacuum, the film is heated and softened and then air is introduced under normal pressure into the upper half of the chamber, so that this alone presses the thermoplastic film down around the product and against the packaging substrate.

In a further modification according to U.S. Patent 3,491,504 In such a method, the softened film is moved mechanically downwards over the fixed packaged goods, whereupon together the soft thermoplastic film is molded onto the product with compressed air.

In all of these known methods, the thermoplastic film pulled over the open area of the vacuum chamber, the packaged goods then either pressed up into the film, the film is pulled down over the product or moved by compressed air. By physically touching the film or product must move, the packaging process slows down,

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it is also necessary that the product is sufficient must be stable to withstand the pressing of the film. Another disadvantage of this method is that if a film is drawn flat or straight over the vacuum chamber, excess film material is needed and that creases easily due to unnecessary movement of the film.

The present invention has set itself the task of eliminating these disadvantages and a new advantageous packaging method to propose.

To solve this problem, a method for vacuum packaging is proposed according to the invention, which thereby is characterized in that the packaged goods are arranged on a base, one in a sheet of flexible material Forms recess and - with at least partial enclosure of the product through the indentation - a pressure differential is applied to the film to bring it into sealing engagement with the packaging to bring under.

According to the present invention, a device for vacuum packaging objects in flexible material is also proposed, which is characterized in that it has a vacuum device which has an open, coverable first

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Has part that forms a vacuum chamber and means for supporting of the packaged goods and means for evacuating this first part, and also a second part to the complete first part, which has a concave inner surface that ends in a lower circumferential edge, which in sealing Engagement with the periphery of the first part can be brought to complete this first part and seal against of the atmosphere, and that further means are present to create an air pressure differential on the concave surfaces, wherein a flexible sheet can be pressed against it, and further means for heating the concave surface.

In the following the invention will be explained in more detail with reference to drawings; show it:

Fig, 1 is a schematic representation of the closure part for a vacuum chamber with a flexible packaging sheet, the covers the opening of the recess in the closure part;

Fig. La is a section through the closure part according to FIG. 1, the arrangement of the heating elements, the vacuum openings and the height adjustment means for the closure member are shown;

Fig. 2 is a schematic representation of the vacuum chamber with closure part, wherein the packaging sheet is deformed in a concave manner and the goods to be packaged and the packaging underlay are in the Chamber are arranged;

3 shows a schematic representation of the vacuum chamber during the evacuation of the space between the packaging base and the packaging document;

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Fig. 4 is a schematic representation of the vacuum chamber after the packaging has been moved against the packaged goods and is in sealing engagement with the packaging base is located;

5 shows a schematic representation of a vacuum "skin" package.

The head piece shown partially in section and schematically in FIG or closure part 3 of the vacuum chamber serves as a seal for the vacuum chamber described below, the Details best shown in Fig. 1 and Fig. La. In the head piece 3 is through the inclined inner wall 15 and a horizontal Wall part with passage opening en 14 a concave space or a depression is formed. A multiple area 4 with an outer opening 6 is located above the passage openings. Heating elements 5 are arranged within the multiple area in order to heat the wall with the passage openings 14. These Heating elements can either be steam lines with heating agent inlet openings 12 and heating medium outlet openings 13, or radiant electric heating elements or resistance heating elements.

The head piece 3 has a vertically circumferential wall or support 16, which can be supplemented by an attachment piece 17 to extend the height of the wall 16 or. when not in use

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to shorten the top section. The top piece 17 corresponds in its shape the shape of the opening of the recess in the head piece 3, so that one can determine the height of the head piece or closure part can be adjusted depending on the different sizes of the packaged goods. ■

In FIG. 2, the vacuum chamber 9 is shown, which has a worktop 8 which is supported by the supports 10. On the Worktop 8 is the base 7 for the packaged goods 2 lying on it. A flexible packaging film 1 is arranged in the recess of the head piece and lines it. The chamber 9 has a chamber space 18 with an outlet opening 11; the chamber 9 has a passage to the head piece, the is formed by the distance between the chamber 9 and the worktop 8.

When carrying out the process, the flexible packaging film 1 as shown in Fig. 1 drawn across the opening of the recess in the closure part 3, and preferably a transparent Packaging material and in particular thermoplastic films made of polyethylene, cross-linked polyethylene, polypropylene, saran, nylon, or polyvinyl chloride and laminates of these materials are used.

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Thermoplastic films are relatively stiff or semi-rigid before being made soft or malleable by heating will. Such heat-softenable thermoplastic films are over the opening of the recess of the head piece laid as it is shown in Fig. 1, wherein the films have either been heated for partial softening beforehand or through the heating elements 5 can be brought to the softening temperature.

After arranging the packaging material or the film 1 is a pressure difference or a vacuum, as indicated in Fig. 2 by the arrow, is applied. This pressure difference or this A vacuum is created at the passage openings 14, in the multiple area 4 and at the outer opening 6. Any Vacuum pump can be used. As a result of the pressure difference, the film 1 assumes the shape shown in FIG. 2 and dresses here the recess of the head piece 3 and takes the same concave shape as the recess in the head piece. In other words, at this point there will be a depression in the Slide 1 formed.

As FIG. 2 shows, the packaged goods are already on the base 7, which in turn lies on the worktop 8. the

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Support 7 for the packaged product is preferably made of gas-impermeable material and, for example, an aluminum foil or an aluminum sheet to be _y or a plastic plate made of polystyrene or foamed polystyrene, a surface coated with gas-impermeable plastic material of cardboard or generally an arcuate transparent or opaque material. As shown in FIG. 2, the concavely deformed film 1 is arranged above the goods to be packaged 2 and the base 7. At this point in time, the head piece or the closure part 3 has not yet been placed on the vacuum chamber 9. Closing takes place as shown in FIG. 3. During this entire working sequence, as shown in FIGS. 2 and 3, a vacuum is constantly applied through the passage openings 14, in the multiple area and at the outer opening 6 in order to maintain the concave shape of the film 1. After closing the vacuum chamber with the head piece 3, a vacuum or a pressure difference is applied to the outlet opening 11, as indicated by the arrow pointing downwards. The arrows on the two sides of the worktop 8 are intended to show that the air or the gas is evacuated from the area between the base 7 and the film 1. The air is sucked out of the surroundings of the packaged goods 2 through the circumferential gap between the chamber 9 and the worktop 8 into the chamber cavity or the chamber space 18 and out of this through the outlet opening 11. As mentioned, during

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the evacuation of the chamber, the concave shape of the film 1, preferably by applying a vacuum to the passage openings 14 and maintained in the multiple area 4. During this process, heat can continue to be supplied, to soften the film 1 if it is a thermoplastic material.

In FIG. 4, the film 1 is shown as it is applied and deformed around the packaging material 2 and is in contact with the substrate 7 stands. The vacuum or the pressure difference at the outlet opening 11 has been maintained during the Vacuum at the external opening 6 is removed and external pressure or normal pressure has been applied, which is caused by the down directed arrow is made clear. You can go through the outside opening 6 also apply overpressure in order to move the film faster and more safely against the packaged goods 2. One can also Apply a negative pressure to the movement and stretching speed to slow down the slide. To move the film 1 against the packaged goods 2 and the substrate 7, it is only required that the pressure on the lower side of the film be less than that on the upper side. For example, at In the process shown in FIG. 3, the vacuum applied through the passage openings 14 was performed on the upper side

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of the film 1 must be equal to or greater than the vacuum that acts on the lower side of the film at the outlet opening 11, so that the concave shape of the film is retained. However, if the film is moved against the packaged goods, as shown in FIG. 4 is shown, the film is pressed against the packaged goods 2 by the vacuum which is applied at the outlet opening 11 The film 1 is pulled or is pressed downward in the direction of the packaged goods 2 by the atmospheric pressure.

In order to maintain the recess or the concave shape of the film 1 in the steps shown in FIGS. 2 and 3, one must usually a concentration of more than 490 mnHg at the openings 14 create. Further, to ensure complete evacuation of the package, a vacuum of more is used as 490 mmHg applied to the outlet opening 11. The best results are obtained with a vacuum of about 710 mmHg on the both openings 11 and 14. As long as the vacuum applied above the film is equal to or greater than that below the film If there is a vacuum, the film remains in its position. When the vacuum above the film is released, it moves downward. When the film moves down, it only needs to travel a short distance before it reaches the top of the packaged goods 2 touches. This short way results

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due to the concave shape of the foil. This gives the slide hardly any opportunity before contact with the packaging gixt and forming folds.

Another advantage of deforming the film 1 into a cavity or depression before it is applied or molded to the packaged goods consists in the fact that the film 1 is approximately in the same plane with the base 7 for the Can clamp packaged goods, as shown in FIG. When the packaged goods 2 and the base 7 are far are arranged below the opening of the vacuum chamber 9, the edges or marginal areas of the film 1 are disproportionate strongly stretched and do not adhere to the edge area of the substrate 7 without difficulty, with furthermore, an excess of unusable film forms in the outer area of the base 7. In addition, stick with the present method, the packaged goods and the base after being introduced into the vacuum chamber in place and And do not have to be moved. This reduces the possibility that the packaged goods on the base 7 is moved. Furthermore, the packaged goods 2 can no longer be caused by the physical movement of the product

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deformed or even destroyed in the direction of the film. Fig. 5 shows a finished package in which the rectangular Packaged goods 2 is covered by the film 1, which is tight applied to the shape of the product. In other words, the packaging material 2 serves as a molded part for the film 1. The film is sealed with the base that carries the packaged item 2. The packaging film 1 is preferably an impermeable one Material, i.e. a film with a relatively low air and oxygen permeability; the same goes for for the base 7. The seal between the film 1 and the base 7 can be done in various ways. For example For example, the film 1 can be coated with an adhesive which is activated by heat. When the slide comes into contact with the wall 15 of the cavity of the head piece due to the heating elements 5 as shown in Fig. 2 is heated, so the Adhesive activated and then, after the film has been applied to the base 7, as shown in FIG. 4, bonded to the base 7. If a polyethylene film is used, an extremely satisfactory one can be obtained by coating with ethylene vinyl acetate by means of heat activatable adhesive layer obtained. For gluing you can also use the base 7 with a material such as polyethylene, so the the same material that is used for the film 1, coat.

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When heated sufficiently, the same materials adhere to one another and make a good seal. Furthermore, one can use a pressure sensitive adhesive or one activated by heat ble Apply adhesive to the base, which is then activated by the ■ heat prevailing in the chamber.

The present method and the device according to the invention are particularly suitable for packaging food when evacuated packaging is required in order to extend the storage time of the products. The various foods require packaging material with different permeabilities for water vapor and oxygen. Thus, the \ ^r erpackungsmaterial be selected according to the properties that correspond to the respective foodstuffs to be packed. You can also work with different gases; For example, the space around the packaged goods can be flushed with an inert gas such as nitrogen, whereupon a pressure difference? is applied to the passage openings 14 so that the film is pressed against the product 2 and the substrate 7. In this way a hermetically sealed package is obtained after sealing.

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Claims (1)

Claims Process for vacuum packaging, in which one has to goods to be packaged on a base, characterized in that a recess is made in a sheet flexible material and - with at least partial wrapping of the product by the recess - a Pressure difference generated on the arch to bring this in. Sealing engagement with the base. 2. Verfeihi'en according to claim 1, characterized in that the recess in the arch is produced by the fact that the arch against a concave surface due to a pressure difference pulls. 3. The method according to claim 2, characterized in that the sheet is a thermoplastic film and that the concave surface to the softening temperature of the thermoplastic Material is heated. 4. The method according to claim 2 or 3, characterized in that the sheet is in sealing engagement with the documents 209819/0573 2K94H is pulled by evacuating the space between the arch and the base. 5. The method according to claim 2 to 4, characterized in that the pressure difference forming the depression is maintained while the sheet lies over the product to be packaged. β ^ method according to claim 5, characterized in that the the pressure difference forming the indentation is eliminated when the sheet is in sealing contact with the substrate, wherein the vacuum is maintained between the sheet and the base, thereby wrapping the sheet around the product to be packaged to snuggle up to. 7. The method according to claim 6, characterized in that the sheet is sealed or glued to the base when nestling around the packaged goods . 8. The method according to claim 1 to 7, characterized in that the product is packaged in a vacuum device which has a first part which forms a vacuum chamber and which contains a support for the product and its base, and 209819/0573 2H94U a second part having a concave surface, the second part towards the first part is movable and movable away again in order to open and close the chamber, whereby the base for the product is arranged to be between the first and second parts of the chamber in the closed position of the Chamber is pinched. 9. Apparatus for performing the method according to claim 1, characterized in that the device has a Is a vacuum system that has an open, coverable first part that forms a vacuum chamber (9) that forms a worktop (8) has for the product to be packaged, furthermore means (11) for evacuating the first part (9), a second part (3), which has a concave inner surface (15) which ends in a lower circumferential edge which is in sealing engagement is to be brought to the circumference of the first part (9) in order to close off and seal off the first part from the atmosphere, Means (14) to create a compressed air differential on the concave surface (15), with a flexible arc attached this can be tightened, and a heating device (5) that heats the concave surface (15), 209819/0573 -19- 21494U 10. Apparatus according to claim 9, characterized in that means (17) are provided to increase the height of the second Part (3) set. 11. Device according to claims 9 or 10, characterized in that that the means (14) for generating a different air pressure on the concave surface (15) from a plurality of vacuum passage openings (14) in the " Surface exist, with these passage openings in open into a multiple area (4). 12. The device according to claim 9 to 11, characterized in that the worktop (8) is a platform (8), the upper one The surface is approximately on the same level as the open upper part of the first part (9). 209819/0573