JPS63203506A - Method and device for packaging food stored in vessel made of plastic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method and apparatus for packaging foods contained in plastic containers.

(Prior art) Conventionally, this type of equipment has been equipped with batch pressurized high-pressure,
There is a medium-low temperature sterilizer (retort), and in order to prevent the shape of the container from deforming due to thermal expansion caused by heating, as is done when sterilizing canned goods, etc., the container is placed in a pressurized tank in a batch style, and the pressure inside the tank is By heating the container while pressurizing it from the outside with a pump or the like, the expansion volume inside the container and the pressure applied from the outside are calculated from the heating temperature, and the pressing force is controlled to prevent the container from deforming.

(Problem to be solved by the invention) However, there is no problem with containers made of metal such as steel plates, such as the canned foods in the above example, but with the strength of the container itself, such as with plastic containers. For items with a very low grade, such as high temperature sterilization (retort),
If it is carried out at a temperature between 120°C and 120°C, the container will easily deform, and to prevent this, the wall must be thicker than necessary than the container body. Sterilization (boil sterilization) at 85°C
Even if the temperature is 100°C or 60°C to 85°C for pasteurization (thermal sterilization), in order to perform pressure sterilization, the wall must be considerably thicker for strength reasons, even if it is not as strong as high temperature sterilization.
Thick-walled containers were a problem because they were unprofitable from a cost standpoint.

In view of this, the present invention reduces the wall thickness of the container to lower the unit price of the container, and also reduces the internal pressure of [-] in advance by plastic deformation of the container,
The aesthetic deformation limit was experimentally tested on containers scheduled for mass production, and a predetermined value between atmospheric pressure and -760 mmHg was set, and containers sealed to a reduced pressure value of [-] were subjected to separate continuous testing. When heated in a low-temperature heat sterilizer, the volumetric expansion of the air remaining in the container changes the internal pressure from [-] to [+] to prevent plastic deformation of the container, making it possible to use even thin-walled containers. The purpose of this invention is to provide a method and apparatus for packaging food stored in plastic containers, thereby overcoming the drawbacks of the prior art.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, in the method of the present invention, when heat-sheeting a lid material to a plastic airtight tray container containing food, the amount of air remaining in the container is reduced. The apparatus of the present invention is characterized in that deformation of the container due to thermal expansion of the remaining amount is prevented during medium-low temperature sterilization by controlling the pressure reduction. A flat plate-like hot plate that moves up and down is provided, and when the hot plate is lowered, the upper end of the machine frame is covered and a depressurizing means is connected to the airtight chamber that can be opened and closed freely. A receiving mold is provided to match the shape of the plastic tray containing food, and a pushing means is provided which completes the heat sealing of the lid material of the tray when the receiving mold is pressed against the hot plate of the airtight chamber by rising. It is characterized in that it is provided below the receiving mold so as to be movable up and down.

(Function) According to this configuration, the amount of air remaining in the plastic tray container containing food by heat sealing with the lid material can be reduced to an economical level that does not cause deformation due to the rigid structure of the tray container. By reducing the pressure to a value set in a test in advance, it becomes possible to package the container in a way that prevents plastic deformation of the container from thermal expansion stress caused by residual air during heat sterilization.

(Example) The present invention will be described below with reference to the example shown in FIGS. 1 to 4.

The packaging method and device according to the present invention comprises a machine frame 2 fixed on a machine base 1, and a flat plate-shaped machine frame 2 which is suspended so as to be able to rise and fall freely by a push-down means 3 provided above the machine frame 2. A hot plate 4, an airtight chamber 5 formed by the hot plate 4 being lowered by the push-down means 3 to cover the upper surface of the machine frame 2, and a decompression means 6 connected to the airtight chamber 5 so as to be openable and closable. , a receiving mold 8 provided on the machine base 1 in the airtight chamber 5 to match the shape of the plastic tray container 7 containing food; and a receiving mold 8 for press-bonding the receiving mold 8 to the hot plate 4. It is comprised of a push-up means 9, etc., which is provided below the receiving mold 8 so as to be able to rise and fall.

The machine base 1 has a flat plate shape and is fixed on a plurality of supports 10, etc., and a cylindrical machine frame 2 having a predetermined thickness is attached to the top surface of the machine base 1 by connecting the machine base 1 and an O-ring etc. It is sealed and secured by fastening means such as bolts.

A mounting plate 12 of a predetermined height is horizontally formed above the machine frame 2 by a plurality of columns 11 provided on the sides of the machine frame 1, and a plurality of cartridge heaters 13 are mounted on the lower surface of this mounting plate 12. A flat hot plate 4 containing such items is suspended.

Further, on the upper surface of the mounting plate 12, a pressing means 3 using an air cylinder for raising and lowering the hot plate 4 is provided,
It is connected to the hot plate 4 by a rod 14 of the push-down means 3.

The hot plate 4 is formed to have the same diameter as the outer diameter of the machine frame 2, and when the hot plate 4 is lowered by the operation of the push-down means 3 and comes into contact with the top surface of the machine frame 2, a seal provided on the top surface is sealed. An airtight chamber 5 is formed inside the machine frame 2 by being sealed with a gasket.

This airtight chamber 5 has a hole 15.1 communicating with the inside and outside of the machine frame 2.
6 is bored, and one is a pressure reducing means 6 using a vacuum pump,
The other end is connected to a pressure gauge 17, an on-off valve 18, etc., respectively.

In addition, in the airtight chamber 5, a receiving mold 8 made of aluminum or the like is provided on the machine stand 1 to match the shape of the plastic tray container 7 in which food is stored.
9, etc., so as to be non-rotatable.

A recess is provided in the lower part of the receiving mold 8, and a horizontal portion of a T-shaped push-up member 20, which is sealed from the airtight chamber 5, is fitted into the recess. .

A support plate 22 suspended from the machine base 1 by a plurality of stay bolts 21 is provided below the machine base 1, and the support plate 22 has a push-up means 9 using an air cylinder on its lower surface.
is fixed.

The rod 23 of this push-up means 9 is provided to protrude above the support plate 22, and its upper end is connected to the push-up member 2.
It is screwed into the vertical part of 0 and becomes one piece.

Therefore, by driving the pushing up means 9, the pushing up member 20
When raised, the receiving mold 8 can be pressed onto the lower surface of the hot plate 4.

Next, a method of packaging using the apparatus of the present invention will be explained.

First, the machine frame 2 is sealed to the machine base 1 using an O-ring or the like, and then fixed using fastening means such as bolts.

Next, food is placed in a plastic tray container 7, a lid material 24 is placed on top of the food, and the tray container 7 is placed on the mold 8 so that the edge thereof is exposed on the upper surface of the mold 8.

Note that silicone rubber is placed between the receiving mold 8 and the tray container 7 for insulation.

Therefore, this receiving mold 8 is put into the machine frame 2, and the push-up member 20
After fitting and fixing the position with respect to the machine frame 1 with the anti-rotation pin 19, the pressing means 3 using an air cylinder is activated to lower the hot plate 4 to the upper surface of the machine frame 2 and cover it. Create an airtight chamber 5 inside 2.

In the next step (see Figure 3), the pressure inside the airtight chamber 5 is reduced to a value preset in a test using a vacuum pump-based depressurization means 6 to the extent that the rigidity of the tray container 7 does not cause deformation over time. When the pressure is lowered to the pressure, the push-up means 9 using an air cylinder is activated to raise the receiving mold 8, and the upper surface of the receiving mold 8 is brought into contact with the hot plate 4 and bonded by thermocompression, whereby the lid material 24 is attached to the tray container 7. Heat sealing using the point seal method is completed.

At this time, the pressure inside the tray container 7 is already reduced, and the container is plastically deformed due to stress caused by thermal expansion. The packaging can prevent this from happening.

Medium-temperature sterilization is performed in a separate heat sterilization device after the vacuum seal packaging described above.

In this embodiment, the push-down means 3 and the push-up means 9 are explained as air cylinders, and the pressure reduction means 6 is explained as a vacuum pump. You may replace it with this.

〔Effect of the invention〕

As the present invention has been explained above, in the invention of the packaging method, compared to the conventional batch type pressurized method (retort), it is possible to heat sterilize food in a plastic airtight container with a large amount of residual air. The effect of container deformation due to thermal expansion stress due to residual air under general atmospheric pressure can be prevented by vacuum-sealing packaging, and medium-low temperature sterilization under continuous atmospheric pressure, which was previously impossible, can be achieved.

By being able to perform medium-low temperature sterilization, it is now possible to connect the pressurized process in a batch system, which was previously required to prevent container deformation, into a continuous line. It also reduces work steps and improves efficiency.

By carrying out medium-low temperature sterilization based on the present invention, it is possible to prevent the color change and softening of the contents, which would occur if the conventional high temperature sterilization is carried out, thereby improving the quality of the contents. can be increased.

This also saves resources by making the plastic container as thin as possible and simplifying its shape.

Container costs can be reduced.

In the invention of the packaging device, both the formation of an airtight chamber and the compression heat source for heat sealing can be formed at the same time, so that heat sealing can be easily performed by simply pushing the tray container up from below onto the hot plate and thermocompression bonding. In addition, since it is mechanically very simple, the number of parts can be reduced and machine costs can also be reduced.

[Brief explanation of the drawing]

Fig. 1 is a side view of a packaging device for food stored in a plastic container according to the present invention, Fig. 2 is a sectional view taken along line A-B in Fig. 1, and Fig. 3 is a lowering of the hot plate shown in Fig. 1. A side view showing the state of
FIG. 4 is a side view showing the state in which the mold shown in FIG. 3 is raised. DESCRIPTION OF SYMBOLS 1... Machine stand, 2... Machine frame, 3... Push-down means, 4
...Hot plate, 5.Airtight chamber, 6.Decompression means, 7.
... Tray container, 8... Receiving mold, 9... Push-up means,
24...Lid material. Applicant's agent Mr. Sato 9 PLJI drawing 3 Fig. 4

Claims (1)

[Claims] 1. When heat-sealing a lid material to a food-filled plastic airtight tray container, the remaining amount of air in the container is controlled to reduce the pressure, so that thermal expansion of the remaining amount during medium-low temperature sterilization is achieved. A method for packaging food stored in a plastic container, characterized in that the container is prevented from deforming. 2. A flat hot plate is provided above the machine frame provided on the machine base and is moved up and down by a push-down means, and when the hot plate is lowered, the upper end of the machine frame is covered and a pressure reducing means is provided in the airtight chamber formed. In addition to being connected so as to be openable and closable, the airtight chamber is provided with a receiving mold that matches the shape of the plastic tray on which the food is stored on the machine stand, and this receiving mold is pressed onto the hot plate of the airtight chamber by rising. 1. A packaging device for food stored in a plastic container, characterized in that a push-up means is provided below the receiving mold so as to be movable up and down, thereby completing the heat-sealing of the lid of the tray.