JPH0276720A - Method and device for manufacturing barrier tray - Google Patents

Abstract

PURPOSE: To obtain a barrier tray suitable for vacuum skin packaging by a method in which a heated barrier film is supplied above the tray of a vacuum chamber, the film and the tray are placed in vacuum, and the film is contacted with the top surface of the tray by ventilating the vacuum chamber. CONSTITUTION: A barrier film 2 is supplied from a roll 1, passed through a radiation heater 3 to be heated, and introduced into a vacuum chamber 5. At the same time, a foamed polystyrene tray 4 is moved from the right to the left and introduced into the vacuum chamber, and the vacuum-heated film 2 is arranged over the tray 4. Since the film 2 is heated, it is bonded to the tray along the terminal end of the tray 4 in the vacuum chamber 5. The vacuum chamber, for example, is evacuated through a vacuum port 6 and ventilated, and the heated barrier film 2 is pressed on the top surface 7 of the tray 4 by the atmospheric pressure. A finished tray 9 with a barrier film layer 2 adhered to the top surface of the tray 4 advances further to be discharged from the vacuum chamber 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a barrier tray suitable for vacuum skin packaging, and particularly to a method for manufacturing a barrier tray directly connected to a packaging line.

In vacuum skin packaging, the product is typically placed on a support member such as a ripening tray and surrounded by a plastic film that conforms to the product and adheres to the support member like a skin. In vacuum skin packaging, the film and support member are gas impermeable and the product containing space is evacuated.

For some time now, cancellous or expanded polystyrene in the form of trays has been used for packaging products, especially food products. The advantages of cancellous polystyrene in tray form are well known. The advantages of this material are that it provides a relatively rigid and durable package and that the tray is relatively inert to the product placed and stored in the I-Sea.

One drawback of cancellous polystyrene trays is their oxygen permeability. When the T-Sheet is used as a packaging material in applications where relatively oxygen-impermeable packaging is desired, some modification of the tray is necessary to impart barrier properties to the tray.

For example, in U.S. patent application Ser. A polystyrene sheet 1~ is bonded to the barrier sheet 1~.

Expanded polystyrene sheet 1 is bonded to the barrier sheet by corona bonding or thermal bonding. Adhesives may be used as an alternative method of bonding the expanded polystyrene to the barrier sheet.

Although these methods are effective in producing expanded polystyrene trays with oxygen barrier properties, some drawbacks still remain. One of these drawbacks is the need for a separate production line that includes a foam extruder, lamination machine, and tray aging machine. A separate manufacturing line is required because the blocked foam waste cannot be mixed with unblocked expanded polystyrene and cannot be flexed or recycled. The inability to recycle foam waste reduces the economics of expanded polystyrene.

Accordingly, it would be desirable to eliminate the step of laminating a barrier film to expanded polystyrene in the form of a web and then thermoforming the tray.

In this regard, U.S. Pat. No. 4,611,456 (Gill
io-tos, etc.) are particularly important. The patent describes the process of molding a support made of an air permeable, semipermeable or impermeable material and laminating and adhesively adhering an impermeable film to the molded support to form a container useful for vacuum packaging. A method of manufacturing an impermeable support is disclosed. Preferably, the film is preheated before being introduced into the vacuum chamber.

In the method for manufacturing a barrier tray according to the present invention, a barrier film is supplied to a film heating means, and the film is heated to about 10
A foamed polystyrene tray heated to 0°C to 200°C and having a top and bottom surface is advanced into a vacuum chamber, a heated barrier film is provided above the tray in the vacuum chamber, and the film and tray are placed under vacuum. and venting the vacuum chamber to bring the film into close contact with the top surface of the tray.

Definition-1 The term “barrier” in the text is defined in Section 73 (STP),
24 hour oxygen permeability] is less than 0 Occ/m2, preferably less than about 100 c/l112, more preferably about 1
It means a polymeric material with less than ce/m2. Such materials include various nylons, such as nylon 6. Particularly preferred materials are ethylene vinyl alcohol copolymers and vinylidene chloride copolymers with comonomers such as vinyl chloride and methyl acrylate.

The term "film" in this text refers not only to monolayer or multilayer films obtained by various extrusion and coextrusion methods, but also broadly to laminates containing one or more layers of oxygen-barrier material. do. Lamination 1
~ are manufactured by conventional lamination techniques, corona bonding, thermal bonding, extrusion coating, etc.

According to FIG. 1, a roll 1 of barrier film 2 is arranged to feed the film 2 to heating means 3. As shown in FIG.

The heating means 3 preferably heats the film at a temperature of 100°C to
Preferably a radiant heater or similar device heating to 200°C. If the heating temperature exceeds about 200° C., the expanded polystyrene tray will be damaged when the heated film is attached to the tray.

The heater 3 is preferably suspended above the means 12 for advancing the tray 4. A barrier film 2 is likewise suspended above the advancing means 12 of the tray 4 and is heated by passing it through a radiant heater 3.

Tray 4 is good! , L, < is made of expanded polystyrene. These l-shies have a top surface 7 and a bottom surface 8.

. When carrying out the method, barrier film 2 is placed in roll 1
It is supplied from the radiant heater 3, heated, and introduced into the vacuum chamber 5. At the same time, the expanded polystyrene tray 4 is moved from left to right in FIG. 1 by any suitable means, as schematically shown in FIG. is arranged above the tray 4.

Since the fill 1\2 is heated, it binds to the tray 4 along the edge of the tray 4 inside the vacuum chamber 5.

The vacuum chamber is evacuated, for example via a vacuum boat 6, and then vented and presses the heated barrier film 2 against the top surface 7 of the tray 4 by means of atmospheric pressure, as shown in FIG.

Both the radiant heater 3 and the vacuum chamber 5 may be conventional commercially available devices, modified as appropriate to allow the introduction and placement of the film and tray into the vacuum chamber as shown. Similarly, advancing means 12 and roller means 16 are preferably conventional devices for transporting and advancing film 2 and tray 4, respectively.

As shown in FIG. 2, the finished tray 9, with the barrier film layer 2 adhered to the top surface of the starting tray 4, is further advanced and removed from the vacuum chamber 5. For ease of understanding, the thickness of the tray 4, particularly the thickness of the barrier film 2, is exaggerated in the illustration.

As shown in Figure 2, the barrier film in this case is
It serves as a transfer mechanism from the vacuum chamber to an additional packaging machine, such as a vacuum skin packaging machine.

Accordingly, products such as meat products are filled into the finished tray 4 at a filling station (not shown), and the package is then sealed by bonding a film or laminate top web by processes such as vacuum skin packaging, which are well known in the art. Complete.

The advantage of this method is that conventional off-the-shelf expanded polystyrene trays can be used in-line, and the finished package can be obtained in-line by adding the barrier component to the tray and sealing it to the top of the l-sea. That's true. There is no need to use costly methods of preparing barrier trays from expanded polystyrene in the form of webs and barrier webs.

It will be apparent to those skilled in the art from the description herein that various modifications are possible. For example, if an opening is provided along the bottom of the tray 4 to allow vacuum evacuation through the bottom of the tray, a rotary vacuum forming machine may be used in place of the vacuum chamber shown. Rotary vacuum forming machines are capable of faster processing than vacuum chambers.

The feeding of the tray to the vacuum chamber may be modified such that the tray is introduced into the vacuum chamber in a direction substantially perpendicular to the path of the barrier film. FIG. 3 is a schematic diagram of a take-off system that feeds trays from a rail to a feeder that feeds two trays at a time into the vacuum chamber.

Of course, any suitable number of trays, from one to six or more, may be fed into the vacuum chamber at the same time. This number depends on the dimensions and limitations of the equipment, the dimensions of the vacuum chamber, etc.

The advantage of this side feeding means is that the temperature at which the film 2 is heated by the heating means 3 is not critical since the tray is not directly exposed to the heat of the heater 3.

In yet another embodiment, the film 3 may be heated inside the vacuum chamber. In this case, the preheating step can be omitted, but the above embodiment is not preferred because of the slow processing speed.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a part of the packaging line of the present invention;
FIG. 2 is a schematic diagram showing another part of the packaging line of the present invention, and FIG. 3 is a schematic diagram of a device for feeding trays into a vacuum chamber. 1... Roll, 2... Barrier film, 3... Heating means, 4... Tray, 5
...Vacuum chamber, 6...Boat, 7...
... Top surface, 8 ... Bottom surface, 12 ... Advance means, 16 ... Roller means.

Claims (9)

[Claims] (1) (a) supplying a barrier film to a film heating means; (b) heating the film to about 100°C to 200°C; (c) introducing a foamed polystyrene tray having a top and a bottom into a vacuum chamber; (d) providing a heated barrier film above the tray in the vacuum chamber; (e) placing the film and tray under vacuum; and (f) venting the vacuum chamber to bring the film into close contact with the top of the tray. Features: Barrier tray manufacturing method. 2. The method of claim 1, wherein the barrier film is fed from a roll. 3. The method of claim 1, wherein the film is heated to about 120<0>C to 180<0>C. 4. The method of claim 1, wherein the film is heated to about 140<0>C to 160<0>C. 5. The method of claim 1, further comprising placing the film and tray under vacuum and sealing the film to the edge of the tray. 6. A method according to claim 1, characterized in that the film and tray are placed under vacuum by extracting air from the vacuum chamber through the bottom of the tray. 7. The method of claim 1, further comprising advancing the tray from the vacuum chamber by advancing a barrier film. (8) A barrier tray manufactured by the method according to claim 1. (9) (a) means for advancing the foam tray; (b) means for advancing the barrier film; (c) means for heating the film; and (d) a vacuum chamber for bonding the barrier film to the foam tray. An in-line barrier tray manufacturing device comprising: