JPS6050647B2 - Electron beam sterilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam sterilizer for continuously sterilizing thin plate-shaped objects having a relatively small area, such as carton base paper used as packaging material, shallow dish-shaped containers, and the like.

As technology advances in goods distribution, the scope of application of the so-called one-way packaging system continues to expand, and paper cartons have come to be used in large numbers for the packaging of various beverages such as milk.

Similarly, many shallow dish-shaped containers made of various plastics, paper, etc. have come into use as simple packaging containers for fresh foods. By the way, such articles intended for food and drink, such as containers and containers, require sterilization treatment prior to use, and for this purpose conventionally, sterilization by immersion in hydrogen peroxide (RO2) or ethylene oxide Chemical sterilization methods such as sterilization were mainly used.

Among these methods, the method using ethylene oxide has the disadvantage that ethylene oxide is gaseous, so sterilization must be performed in batches, and it is difficult to sterilize in-line directly connected to automatic packaging machines. Generally, J sterilization treatment using H2O2 has been employed for a long time.

According to this method, this is liquid H. O. Continuous sterilization is possible because it is simply immersed in water, which makes in-line sterilization easier.It is also expected that the heated Lu-00 will have the effect of cleaning the object to be sterilized, and it is possible to use a This is because sterilization treatment can be performed. However, since this method is a wet sterilization method, there is a possibility that H2O2 may remain in the sterilized items, so even if H2O2 actually remains, it may be a trace amount that cannot be detected. However, the use of H2O2 has tended to be discontinued due to the psychological allergy to H2O2 that exists among some users.

Therefore, as an alternative to such chemical sterilization methods, sterilization methods using irradiation with gamma rays, ultraviolet rays (UV), etc. have been proposed.

Among these, the sterilization method using gamma rays is an effective sterilization method in principle, as gamma rays have the property of penetrating packaging materials such as plastic, making it possible to perform in-line sterilization in the final step of the packaging process. There are disadvantages in that the physical properties of the packaging material tend to deteriorate due to gamma ray irradiation, such as a decrease in the strength of the seal portion of the packaging material and the adhesion of odors.

In addition, from a practical point of view, cobalt-60 (CO6) is used as a gamma ray source.
O) is often used, but as a result, it has disadvantages such as a limited period of use (short half-life of 5 years) and the need for a sealing device, making it difficult to handle. However, considering the general psychological allergy to radioactive materials, it is quite difficult to use it as a practical material. On the other hand, the sterilization method using W irradiation is easy to handle because UV has less effect on the human body than other radiations.
There are five advantages: there is almost no need to consider psychological allergies.

However, in the past, it was difficult to obtain a sufficiently strong U source, so it was rarely used alone and was mainly used as an auxiliary means.
With the development of lamps, it has become easy to provide sufficient sterilizing power! As a result, it has come to be used as one of the most effective sterilization methods. However, since we want UV to have the ability to penetrate objects, when targeting packaging materials, it only acts on the surface of the material, and if there is dirt attached, it cannot sterilize that part. Since it is incomplete, it has the disadvantage that a reliable sterilization effect cannot always be expected.

Therefore, as a method to eliminate these drawbacks, a sterilization method using electron beam irradiation was proposed and has been put into practical use.

This method sterilizes packaging materials by emitting high-energy electron beams accelerated by high voltage into the atmosphere through an electron beam-transmitting window. Because it does not require the use of electron beams, it is easy to use in-line and handle, and by increasing the energy of the electron beam, considerable penetrating power can be obtained, making it an excellent method for sterilizing packaging materials for food and beverages. Because of this, it has become widely used. However, from a practical point of view, there is a limit to the increase in accelerating voltage, and therefore there is also a limit to increasing the energy of the electron beam. As a result, electron beam sterilizers that can operate in-line in combination with packaging machines, etc., have traditionally been limited to those that can be used for long strip-shaped packaging materials. It was hot.

In other words, long strips of paper, plastic film, and other packaging materials are usually handled as rolls wrapped around a suitable spool or core material, and the rolls are used for sterilization and other treatments. If you pull out the packaging material while unwinding it sequentially, it will become part of the transport mechanism and be transported, so you can simply pull the packaging material out of the roll while passing through the electron irradiation section, and it will not only remove the front and back sides of the packaging material, but also the front and back sides of the packaging material. It is now possible to sterilize the inside of the package in-line, and it is also now possible to sterilize the stacked packaging materials in-line at the same time by using high-energy electron beams that are practically available. ,
In addition to long strip-shaped packaging materials, for example, the raw material paper used as the base for various beverage cantons (raw material paper cut into a predetermined shape, or it can be pasted onto a body and inflated to form a cylinder immediately after being inflated). In the case of packaging materials that are divided into relatively small shapes, such as containers that are shaped like shallow dishes or containers that are shaped like strips, cannot be used as part of the conveyance mechanism, and must be conveyed by means of conveyance such as a chain conveyor or by various holding mechanisms.

Therefore, in principle, complete sterilization is possible, but from a practical standpoint, sterilization of the transport mechanism and the area where the packaging material is in contact with the transport mechanism tends to be incomplete, and a sufficiently reliable sterilization effect cannot be achieved. I can't wait.

Therefore, the conventional electron beam sterilizer has the drawback that it is difficult to obtain an apparatus that can operate in-line on divided thin plate-shaped packaging materials.

The object of the present invention is to eliminate the drawbacks of the prior art described above, and to transport a thin plate-like packaging material, such as a cardboard base paper, which is divided into relatively small sizes, by sandwiching it between two strip-like films. With a device that enables continuous electron beam irradiation, it is possible to reliably prevent the thin packaging material sandwiched between two strips of film from shifting during transportation, and to ensure reliable sterilization at all times. An object of the present invention is to provide an electron beam sterilization device capable of carrying out the sterilization.

In order to achieve this object, the present invention has a conveying means equipped with a plurality of bar-shaped pushing members that are parallel to each other and move in a direction perpendicular to their length while maintaining a predetermined interval. The present invention is characterized in that the rod-shaped pressing member of the conveying means is pressed against at least one surface of two strips of film sandwiching the thin packaging material between them, and the films are conveyed.

Embodiments of the electron beam sterilizer according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side cross-sectional view showing an embodiment of the present invention. In the figure, 1 is an electron beam generator (referred to as an EB device), 2 is an electron beam transmission window, 3 is an electron beam irradiation chamber, and 4 is an irradiation chamber. 3 outer wall, 5
1 is a first opening, 6 is a second opening, 7 and 8 are supply-side conveyance chains, 9 and 10 are take-out side conveyance chains, 11 is an EB reflector, 12 is a side seal mechanism, and 13 14 is a cooling mechanism, 14 is a seal cutter mechanism, 15 to 18 are chain drive motors, 19 is a supply mechanism for divided thin plate packaging material (hereinafter simply referred to as packaging material), 20 and 21 are rolls on the film supply side, 22 and 23 are film winding rolls, 24 is a seal waste winding roll, 25 is a conveyor for sterilized packaging materials, and 26 to 30 are aseptic rooms.

In addition, ■~A4 are the first films, BO-B4 is the second film, CO-C3 is the packaging material, and E and eO are seal wastes.

The EB device 1 is supplied with operating power from a power supply device (not shown), and emits a high-energy electron beam from the electron beam transmission window 2.

The electron beam irradiation chamber 3 is formed by a wall 4 containing a radiation (for example, X-ray) shielding material such as lead, and is provided with first and second openings 5 and 6.

First and second films A are wound on rolls 20 and 21. , bO consist of long strips of heat-sealable plastic material, such as polyethylene, which are pulled out as films Al, bl by a number of guide rollers, overlapped with each other, and then placed into the electron beam irradiation chamber 3. The chains 7 and 8 are pulled in through the first opening 5 and
and is transported onto the maze by guide block B, and then E
After being irradiated with a high-energy electron beam directly under the electron beam transmission window 2 of the B device 1, the chains 9 and 10 and the guide block B
The film is conveyed in a maze-like manner through the second opening 6, taken out of the electron beam irradiation chamber 3, and entered into the sterile chamber 26. After being peeled off from each other, the film A3, ■ is formed into the sterile chamber 27.
, 28, the film A4, b is placed on the winding rolls 22, 23 in
It is wound up as 4. FIG. 2 shows details of the chains 7, 8 in a perspective view. Chains 7 and 8 have multiple presser rollers R
It is made up of two endless chains formed in the shape of a ladder, and is held movably along a predetermined path by a large number of guide rollers G. These chains 7 and 8 are driven by drive motors 15 and 16 (FIG. 1) to run at the same speed in the direction of the arrow shown. Incidentally, the chains 9 and 10 are also similar, but only the running directions are opposite. next,
The operation of the embodiments shown in FIGS. 1 and 2 will be explained.

First, the EB device 1 is operated to irradiate the electron beam irradiation chamber 3 with a high-energy electron beam, and then the inside of the electron beam irradiation chamber 3 and the sterile chambers 26 to 29 are pre-purified by an appropriate method, such as by spraying H2O2. First and second films A while sterilizing.

, bO from the respective rolls 20 and 21, and the side seal mechanism 12 and the cooling mechanism 13 as shown in FIG.
, opening 5, chains 7, 8, directly below electron beam transmission window 2,
The chains 9, 10, the opening, and the seal cutter mechanism 14 are sequentially passed through a predetermined path, and then wound onto the respective rolls 22, 23 in the sterile chambers 27, 28. Next, roll 22
, 23 and the drive motors 15 to 18 of each chain 7 to 10 are rotated at a predetermined rotational speed, and the first film is also rotated to A4 and the second film B. ~B4, and each chain 7-10
The packaging materials C in the stacker are all moved at the same speed and the packaging material supply mechanism 19 is operated at the same time. are taken out one by one and placed on the first film a1 as the packaging material C1. This state is shown in Figure 3, A. Note that in FIGS. 3 to 6, A is a view from the front, and the mouth is shown in a side view or a cross section. The film a1 travels with the packaging material C on it, and is overlapped with the second film Kg by the guide rollers G1 and G2 before the side seal mechanism 12, as shown in FIG. The packaging material C1 is sandwiched between them, and then the side ends of the first and second films A2 and b2, which are overlapped while passing between the side seal mechanisms 12, are heat-sealed to form a sealed portion S. is formed.

As a result, the packaging material C2 is sealed between the first and second films A2 and b2 before being carried into the electron beam irradiation chamber 3. In this way, the sealed part S is heat-sealed.
is formed, and the first and second films A2 and b2 in which the packaging material C1 is enclosed are passed through the cooling mechanism 13 and exposed to electron beam irradiation from the first opening 5, except for the temperature rise caused by heat sealing. Go into room 3 and take guide block B and chain 7,
8, the traveling direction is changed from the horizontal direction to the downward direction, and then the direction is changed again to the horizontal direction, and the electron beam is passed under the electron beam transmission window 2 of the EB device 1. At this time, films A2 and Y formed by chains 7 and 8 and guide block B
) 2 and packaging material C2, as is clear from FIG. , advance while pressing against block B. Next, in the part where the films A2 and b2 are descending almost vertically, the rollers R of the chains 7 and 8 are in contact with each other with the films A2 and b2 sandwiched between them, as shown in Figure 5 (a) and (b). Transport is carried out at Therefore, the feeding and packaging of the chains 7, 8 are adjusted so that the rollers R of the chains 7, 8 are in contact with the films A2, b2 exactly at the portions where the packaging material C2 does not exist, as shown in FIG. It is necessary to synchronize the operations of the material supply mechanism 19.

In this way, the packaging material C2, which is sandwiched between the first and second films A2 and (2), passes directly under the electron beam transmission window 2 one after another as the films A2 and b2 travel, and is exposed to high-energy electron beams. It is irradiated and sterilized. The relationship between the energy of the electron beam and the sterilization effect at this time will be explained as follows. The thickness of the second film A2 is Tal and the density is ρ.

, the thickness of the second film ■ is T, the density is ρ5, and the packaging material C
The thickness of 2 is T. , the density is ρ. Then, in general Ta=T
Since b<TO and ρ8=ρb<Pc, it is expressed as (thickness×density) as shown in FIG. 7A. Therefore, when the packaging material C2 sandwiched between the films A2, Y)2 is irradiated with an electron beam, when the energy of the electron beam exceeds a certain level, the surface film The packaging material C2 produces a larger absorbed dose, and can also provide a sufficient absorbed dose to the film A2 on the back side.

Therefore, if the acceleration voltage of the EB device 1 is set to 400 kV or higher, and the beam current and the transport speed of the film A2, Y)2 are kept at predetermined values, the packaging material C2 sandwiched between the films A2 and b2 is It can be seen that a sufficient bactericidal effect can be imparted to these films, and a sufficient bactericidal effect can also be imparted to these films.

At this time, in the embodiment shown in FIG.
, b2 and directly below the electron beam transmission window 2 of the EB device 1, that is, the part where the electron beam that has passed through the film A2, ■, or in addition, the packaging material C2 reaches, is made of lead or the like. An EB reflecting plate 11 made of an electron beam reflecting material is provided, and reflects the electron beam that has reached this plate to form the film A2, Y)
By irradiating 2 and the packaging material C2, a so-called backscattering effect is promoted to further increase the absorbed dose, thereby achieving an even better sterilization effect. This EB reflector 11 is
A radiation block may be used, but in either case, heat is generated due to the impact of the electron beam, so it is necessary to provide an appropriate cooling device to prevent the films A2, b2 and packaging material C2 from rising in temperature. In this way, the films A2 and b2 that have passed directly under the electron beam transmission window 2 of the EB device 1 and the packaging material C2 that is sandwiched between them and are in an enclosed state change their course upward by the chains 9 and 10 and the block B, and are almost vertical. It then changes its course upward and horizontally again and is taken out from the electron beam irradiation chamber 3 into the sterile chamber 26 through the second opening 6, and is cut by the cutter of the seal cutter mechanism 14 as shown in FIG. A, C]l As shown, the seal portion S is cut and the seal waste e is cut out.

After that, the first film A3 is placed at the position of the guide roll G3.
is separated from the second film F and wound onto the roll 22 in the sterile chamber 27 as a sterilized film A4. As a result, the packaging material C2 placed on the first film A3 separates from the first film A3 at the position of the guide ronilla G3, becomes a sterilized packaging material C3, and falls onto the conveyor 25. It passes through the sterile room 30 and is transported to a predetermined location,
It is supplied to automatic food packaging machines that have an in-line configuration. Further, the second film (2) is introduced into the sterile chamber 28 through the sterile chambers 26 to 30, and wound onto the roll 23 as a sterilized film B4. Further, the edge waste e separates from the first and second films A3 and b3 at the position of the guide roller G3, and is wound onto the roll 24 in the sterile chamber 29. Therefore, according to this embodiment, packaging material C.

- Since C3 is conveyed in a sealed state sandwiched between two films AO-A4 and AO-B4 through which the first and second electron beams can easily pass, the entire film is not covered during electron beam irradiation treatment. This eliminates the need for electron beam irradiation together with other transport means such as conveyors, making it possible to completely perform electron beam sterilization from a practical standpoint. can. Also,
Such electron beam sterilizers require a labyrinth to prevent radiation such as X-rays generated by electron beam irradiation from leaking outside from the entrance or exit for packaging materials, etc. When it comes to packaging materials other than those in the form of long strips, there are many concerns that the transportation mechanism and maze configuration will be complicated, and that it will be difficult to put them into practical use. Chain 7-1 with
0 and guide block B are used, and the two films A2 and b2 are conveyed while being held down by roller G and guide block B, so they are sandwiched between the two films A2 and B2. It is possible to transport the packaging material C2 in any direction without causing a shift in the position, and as in the above embodiment, the location where the electron beam is irradiated and the openings 5 and 6 are different.
It becomes easy to construct a labyrinth by increasing the height of the position where the is provided, and leakage of X-rays and the like can be sufficiently suppressed.

In addition, in this example, the first and second films AO, b
Since O is also obtained as sterilized films A4 and b4, these can not only be used repeatedly but also supplied to the market as sterilized packaging materials, thereby increasing the operating rate of the EB device.

In addition, at this time, these films A. If the polyethylene film is already a polyethylene film, crosslinking progresses sequentially by electron beam irradiation, so that a modified and sterilized film can be obtained after repeated use. However, in the above embodiment, since the side seal part S is cut off each time it is used, packaging materials of different sizes may be used so that there is no problem even if the width becomes gradually narrower. This will require some effort.
Furthermore, in the above embodiment, the first and second films A are sealed by operating the side seal mechanism 12.

, bO, but as an embodiment of the present invention,
Packaging material C is simply used without this sealing. Film A. ，
It may also be operated in a state where it is simply inserted between bO. According to this embodiment, there is no need to use the cooling mechanism 13 and the seal cutter mechanism 14, and naturally seal waste e is not generated. Therefore, even if the films A4 and b4 are used repeatedly, the widthwise dimension does not become short, and it becomes easy to use them repeatedly many times, and a modified film can also be easily obtained. Furthermore, in the above embodiment, sterile air may be constantly supplied from the sterile room 30.

In this way, sterile air is sent from the sterile chamber 26 into the electron beam irradiation chamber 3 through the second opening 6, and the irradiation chamber 3 is
Since the pressure inside is kept slightly higher than atmospheric pressure, outside air is prevented from entering through the first opening 5 on the side where the films A2, ■ and the packaging material C2 are supplied, and the sterilized films and The sterility of the packaging material can be maintained even better. However, in the above embodiment, the movement of the superimposed first and second films A2, (2) in the electron beam irradiation chamber 3 is guided by the presser rollers R attached to the chains 7 to 10. Because I try to do it,
Even when the transport direction of the first and second films A2 and b2 is bent or perpendicular, the packaging material C2 can be reliably transported without shifting, and the sterilization process by electron beam irradiation can be carried out sufficiently. However, as a further embodiment of the present invention, these pressing rollers R may be made of a permanent magnet or a permanent magnet and a magnetic material.

By doing this, when the holding rollers R of the chains 7 and 8 are pressed against both sides of the films A2 and b2 in the electron beam irradiation chamber 3, a magnetic attraction force is generated between these opposing rollers R. As a result, the rollers R attract each other, sandwiching the films A2 and b2 even more strongly, and holding the packaging material C2 even more reliably to further reduce the possibility of displacement. As explained above, according to the present invention, a thin plate-like packaging material, such as a tonne base paper, which is divided into relatively small shapes, is conveyed by being sandwiched between two long strip-like films. In this electron beam sterilizer, the conveyance state of packaging materials can always be maintained correctly, so that the disadvantages of the conventional technology can be eliminated, and the sterilization treatment of divided packaging materials by electron beam irradiation can be performed continuously and reliably. It is possible to provide an electron beam sterilizer that can easily perform in-line sterilization treatment and can also sterilize long strip-shaped packaging materials at the same time.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view showing an embodiment of an electron beam sterilizer according to the present invention, Fig. 2 is an enlarged perspective view of a part of the chain mechanism, and Fig. 3 is a Figure 4 A,
5A and 6B are explanatory diagrams showing the operation of the embodiment shown in FIG. 1, and FIG. be. 1... Electron beam generator (E-cutting station), 2...
...Electron beam irradiation window, 3...Electron beam irradiation room, 4
...Outer wall, 5...First opening, 6...
... second opening, 7, 8 ... conveyance chain on the supply side, 9, 10 ... conveyance chain on the extraction side,
11...EB reflection plate, 12...Side seal mechanism, 13...Cooling mechanism, 14...
... Seal cutter mechanism, 15-18 ... Chain drive motor, 19 ... Packaging material supply mechanism,
21-24...roll, 25...conveyor, 26-30...sterile room? ~A4...
- First film, BO to B4... Second film, CO-C3... Packaging material.

Claims (1)

[Claims] 1. An electron beam sterilization device that enables continuous electron beam irradiation by sandwiching and conveying a plurality of relatively small-sized thin plate-like objects and two long strip-like films. , a plurality of rod-shaped pressing members are provided, and a conveying means is provided for making the plurality of rod-shaped pressing members parallel to each other and sequentially moving them at a predetermined interval in a direction perpendicular to their length direction. The two strips of film can be conveyed without causing displacement of the thin plate-like object by pressing a rod-shaped pressing member against one or both surfaces of the two strips of film. Electron beam sterilizer. 2. In claim 1, the conveying means comprises:
It is composed of two endless chains and a plurality of rollers mounted in a ladder-like manner at equal intervals between these two endless chains, and the above-mentioned pedestal pressing member is constituted by these plurality of rollers. Characteristic electron beam sterilizer. 3 In claim 2, the plurality of rollers are composed of permanent magnets and magnetic materials, and when pressed against both sides of the two strips of film, a magnetic attraction force acts between these rollers. An electron beam sterilizer characterized by being configured as follows.