JPS6326014B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus for sterilizing sterilization by electron beam irradiation, and is particularly applicable to thin sheets of relatively small area such as carton base paper used as packaging materials and shallow dish-shaped containers. The present invention relates to an electron beam sterilizer suitable for continuously sterilizing objects.

[Conventional technology]

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 packaging various beverages such as milk. Similarly, various plastics,
Many shallow, plate-shaped containers made of paper have come into use.

By the way, such items such as cartons and containers for food and drink require sterilization treatment prior to use, and for this purpose conventionally, sterilization by immersion in hydrogen peroxide (H ₂ O ₂ ) or ethylene Scientific sterilization methods, such as sterilization with oxides, were mainly used.

Among these, the method using ethylene oxide is
Since ethylene oxide is a gas, sterilization must be carried out in batches, and it is difficult to sterilize in-line directly connected to _an automatic packaging machine _. Sterilization treatment has been used since ancient times. This is because, according to this method, continuous sterilization is possible because it is simply immersed in liquid H ₂ O _2. Therefore, in-line sterilization is easy, and heated
This is because H ₂ O ₂ can be expected to have a cleaning effect on the object to be sterilized, and reliable sterilization can be carried out including the transport means.

However, since this method is a wet sterilization method, there is a possibility that H ₂ O ₂ remains in the sterilized items, so even if H ₂ O ₂ actually remains, it will be in trace amounts that cannot be detected. Despite this, there is a tendency for its use to be discontinued due to the psychological allergy to H ₂ O ₂ 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 has the property of penetrating packaging materials such as plastic, so in-line sterilization is possible in the final step of the packaging process, and it is an effective sterilization method in principle. , γ
There are disadvantages in that radiation irradiation tends to cause deterioration in the physical properties of the packaging material, such as a decrease in the strength of the seal portion of the packaging material and the adhesion of odors. In addition, cobalt-60 (Co60) is often used as a gamma ray source from a practical standpoint, but it has a limited period of use (its half-life is short, 5 years) and requires a shielding device. Not only does it have disadvantages such as getting old and becoming difficult to handle,
Considering the general psychological allergy to irradiated substances, the problem is that it is quite difficult to operate this system as a practical device.

On the other hand, sterilization methods using UV irradiation have the advantage that UV has less of an effect on the human body than other radiations, so it is easy to handle and there is almost no need to consider psychological allergies. . However, in the past, it was difficult to obtain a sufficiently powerful UV source, so it was rarely used alone and was mainly used as an auxiliary means, but in recent years, powerful UV lamps have been developed. As it has become easier to provide sufficient sterilization power, it has come to be used as one of the effective sterilization methods.

However, UV has a limited ability to penetrate objects, so when targeting packaging materials, it is only used on the surface of the material, and if there is dirt attached, sterilization will be incomplete in that area. Therefore, there was a drawback that a reliable sterilizing effect could not always be expected.

Therefore, as a method to eliminate these drawbacks, a sterilization method using electron beam irradiation has been proposed and put into practical use. In this method, high-energy electron beams accelerated by high voltage are emitted into the atmosphere through an electron beam transmission window, and are irradiated onto packaging materials, etc., to sterilize them.
In addition to being completely dry sterilized, there is no need to use radioactive materials, making it easy to use in-line and handle.
Moreover, if the energy of the electron beam is increased, a considerable penetrating power can be obtained, so it has extremely excellent properties as a method for sterilizing packaging materials for food and drink products, and has come to be widely used.

[Problem that the invention seeks to solve]

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, so the penetrating power of the electron beam is r
Electron beam sterilizers that can operate in-line in combination with packaging machines have traditionally been used for long strip-shaped packaging materials. The problem was that it was limited to certain things.

In other words, long strips of paper, plastic films, and other packaging materials are usually handled as rolls wrapped around a suitable spool or core material, and the rolls are sequentially rolled during sterilization and other treatments. If you pull out the packaging material while unwinding it, it will become part of the transport mechanism and be transported, so simply pulling the packaging material out of the roll while passing through the electron irradiation section will remove the front and back surfaces of the packaging material. It is now possible to sterilize the inside of the packaging material in-line, and it is now also possible to sterilize the stacked packaging materials in-line at the same time by using high-energy electron beams that are practically available. Other than long strip-shaped packaging materials, for example, carton base paper used as the base of various beverage cartons (material paper cut into a specified shape from raw material paper, or which is further pasted onto a body and inflated into a cylindrical shape) In the case of packaging materials that are divided into relatively small shapes, such as containers that have been prepared in the form of a shallow dish) or containers that are formed into shallow dish shapes, packaging materials that are divided into relatively small shapes, such as containers that have been prepared in the form of a It cannot be used as a storage device, and must be transported by means of transport 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 parts where the packaging material is in contact with the transport mechanism tend to be incomplete, and a sufficiently reliable sterilization effect cannot be obtained. 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.

An object of the present invention is to eliminate the drawbacks of the prior art described above, to be able to continuously and reliably sterilize thin packaging materials such as carton base paper that are divided into relatively small pieces, and to operate in-line. To provide an electron beam sterilizer capable of

[Means for solving problems]

In order to achieve this object, in the present invention 1, two long strip-like films are overlapped and conveyed, and a thin plate-like packaging material is sandwiched between these two films to pass through an electron beam irradiation section. The second invention is characterized in that the sterilization process can be carried out continuously.Furthermore, in the second invention, two long strip-shaped films are overlapped and conveyed, and these two
A thin plate-like packaging material is sandwiched between two films, and both ends of the two films are continuously sealed, and then passed through an electron beam irradiation section, and then the two films are sealed. The feature is that continuous sterilization treatment can be performed by cutting off the sterilized portion.

[Effect]

Since the thin plate-shaped objects to be sterilized are held within two films, they are transported together by transporting the films, and as a result, a plurality of objects can be processed continuously. During this time,
There is no contact with other objects that could lead to incomplete sterilization, and a reliable sterilization process can be carried out online.

[Example] Hereinafter, an example of the electron beam sterilizer according to the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view showing one 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 the outer wall of the irradiation chamber 3, 5 is the first opening, and 6 is the second
openings, 7 and 8 are conveyance chains on the supply side,
9 and 10 are conveyance chains on the extraction side, and 11 is a conveyance chain on the extraction side.
EB reflector, 12 is a side seal mechanism, 13 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), 2
0, 21 are film supply rolls, 22, 23
is a film winding side roll, 24 is a seal waste winding roll, 25 is a conveyor for sterilized packaging materials,
26 to 30 are sterile rooms.

Note that a ₀ to _{a 4} are the first film, and b ₀ to b ₄ are the second film.
, c ₀ to _{c 3} are packaging materials, and e and e ₀ 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 contains radiation such as lead (for example,
The wall 4 is formed by a wall 4 containing a cylindrical material and is provided with a first opening 5 and a second opening 6 .

The first and second films a ₀ , b ₀ wound on rolls 20 and 21 are elongated strips of heat-sealable plastic material, such as polyethylene, and are rolled by a number of guide rollers _. , b ₁ , stacked on top of each other, drawn into the electron beam irradiation chamber 3 through the first opening 5, conveyed in a labyrinth by chains 7 and 8 and guide block B, and then exposed to the electron beam irradiation chamber 3. Device 1
After being irradiated with a high-energy electron beam directly under the electron beam transmission window 2 of
is taken out of the electron beam irradiation room 3 and transferred to the sterile room 2.
6, and after being torn off from each other, the film a ₃ ,
b ₃ , and the winding roll 2 in the sterile room 27, 28
2 and 23 are wound up as films a ₄ and b ₄ .

FIG. 2 shows the chains 7, 8 in detail in a perspective view. The chains 7 and 8 are two endless chains formed in a ladder shape by a plurality of presser rollers R, and are held movably along a predetermined path by a number of guide rollers G. ing. These chains 7 and 8 are driven by drive motors 15 and 16 (FIG. 1) at the same speed in the directions indicated by the arrows. Incidentally, the same applies to chains 9 and 10, but
Only the direction of travel is reversed.

Next, the operation of the embodiments shown in FIGS. 1 and 2 will be explained.

First, the EB device 1 is operated to irradiate a high-energy electron beam into the electron beam irradiation chamber 3, and then the inside of the electron beam irradiation chamber 3 and the sterile chambers 26 to 29 are irradiated with an appropriate method.
For example, the first and second films a ₀ and b ₀ are pulled out from the respective rolls 20 and 21 while being pre-sterilized by spraying with H ₂ O ₂ , and the side seal mechanism 12 and the cooling mechanism 13 are removed as shown in FIG. , opening 5,
After passing through a predetermined route in order: chains 7 and 8, directly below electron beam transmission window 2, chains 9 and 10, opening 6, and seal cutter mechanism 14, it is wound onto rolls 22 and 23 in sterile chambers 27 and 28, respectively.

Next, rolls 22, 23 and each chain 7 to 10
The drive motors 15 to 18 of are rotated at a predetermined rotational speed, and the first films _a0 to _a4 and the second films _b0
~ b ₄ , and each chain 7 to 10 are all run at the same speed, and at the same time, the packaging material supply mechanism 19 is operated to take out the packaging materials c ₀ from the stacker one by one and place them on top of the first film a ₁ . Place it as packaging material c ₁ . This state is shown in Figure 3 A and B. Note that in FIGS. 3 to 6, A shows the view from the front, and B shows the side or cross-section, respectively.

The film A ₁ travels with the packaging material C ₁ placed thereon, and guide rollers G ₁ and G ₂ pass before the side seal mechanism 12.
is superimposed on the second film b ₁ by
As shown in Figures A and B, the packaging material c ₁ is sandwiched between them, and then the first and second films overlapped while passing between the side seal mechanism 12.
Both end portions of a ₂ and b ₂ are heat sealed to form a sealed portion S. As a result, the packaging material c ₂ is separated from the first and second films before being carried into the electron beam irradiation chamber 3.
It is sealed between a ₂ and b ₂ .

In this way, the first and second films are heat-sealed to form a sealed portion S, and the packaging material _c1 is encapsulated.
a ₂ and b ₂ pass through the cooling mechanism 13, remove the temperature rise caused by the heat seal, and proceed into the electron beam irradiation chamber 3 through the first opening 5, and then enter the guide block B and chains 7 and 8. Therefore, the direction of travel is changed from the horizontal direction to the downward direction, and then the direction is changed again to the horizontal direction and passed under the electron beam transmission window 2 of the EB device 1. At this time, the conveyance state of the films a ₂ , b ₂ and the packaging material c ₂ by the chains ₇ and 8 and the guide block B is clear from _FIG . The roller R of the chain 7 comes into contact with the part where the packaging material _c2 is not present and advances while pressing it against the block B. Next, in the part where films a ₂ and b ₂ are descending almost vertically, chains 7 and 8 are connected as shown in Figure 5 A and B.
The conveyance is carried out with the rollers R of 1 and 2 in contact with each other with the films a ₂ and b ₂ sandwiched therebetween.

Therefore, the chains 7 and 8 are arranged so that the rollers R of the chains 7 and 8 are in contact with the films a ₂ and b ₂ exactly at the portions where the packaging material c ₂ does not exist, as shown in FIG. 5A and 5B. It is necessary to synchronize the feeding and the operation of the packaging material supply mechanism 19.

In this way, the packaging material c ₂ sandwiched between the first and second films a ₂ and b ₂ sequentially passes directly under the electron beam transmitting window 2 as the films a ₂ and b ₂ travel. Sterilization is performed by irradiation with high-energy electron beams.

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 first film a ₂ is t _a , the density is ρ _a , the second film a 2
If the thickness of the film b ₂ is t _b , the density is ρ _b , the thickness of the packaging material c ₂ is t c , and the density is ρ _c , generally t _a = t _b <t _{c ,} ρ _a

= ρ _b < ρ _c , so when converted into (thickness x density), it becomes as shown in Fig. 7A.

Therefore, when the packaging material c ₂ sandwiched between the films a ₂ and b ₂ is irradiated with an electron beam, if the energy of the electron beam exceeds a certain level, the surface film b will be damaged as shown in FIG. Packaging material _c2 produces a larger absorbed dose than package material _c2 , and a sufficient absorbed dose can also be given to the film _a2 on the back side.

Therefore, the acceleration voltage of the EB device 1 is set to 400kV, for example.
If the beam current and transport speed of films a ₂ and b ₂ are maintained at predetermined values, sufficient sterilization effect can be achieved even on packaging material c ₂ sandwiched between films a ₂ and b ₂ . It can be seen that sufficient bactericidal action can be imparted to these films a ₂ and b ₂ as well.

At _this time _, in the embodiment shown in _{FIG .} In addition, an EB reflecting plate 11 made of an electron beam reflecting material such as lead is provided at the portion where the electron beam that has passed through the packaging material c ₂ reaches, and reflects the electron beam that has reached this plate to form the film a ₂ , b again. ₂ and the packaging material c ₂ to further increase the absorbed dose.
It is designed to promote the so-called backscattering effect, thereby providing an even better sterilizing effect. This EB reflector 11 may be a reflective block, but in either case, it generates heat due to the impact of the electron beam, so it cannot be used with films a ₂ , b ₂ or packaging materials.
It is necessary to provide a suitable cooling device to prevent the temperature of c ₂ from rising.

In this way, the films a ₂ and b ₂ that have passed directly under the electron beam transmitting window 2 of the EB device 1 and the packaging material c ₂ sandwiched therebetween are connected to the chains 9 and 10 and the block B.
It changes its course upward by the arrow, moves almost vertically, changes its course upward again horizontally, and enters the second opening 6.
is taken out from the electron beam irradiation chamber 3 into the sterile chamber 26, and the seal portion S is cut by the cutter of the seal cutter mechanism 14 to cut out the seal waste e as shown in FIG. It will be done. after that,
At the position of the guide roller _G3 , the first film _a3 is separated from the second film _b3 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 is moved to the first position at the position of the guide roller _G3 .
The film _A3 separates from the film A3, becomes a sterilized packaging material _C3 , falls onto the conveyor 25, passes through the sterile room 30, and is transported to a predetermined location, such as an automatic food packaging machine with an in-line configuration. is supplied to Further, the second film b ₃ is introduced into the sterile chamber 28 through the sterile chambers 26 to 30 and wound onto the roll 23 as a sterilized film b ₄ . Furthermore, the edge waste e has the first and second parts at the position of the guide roller _G3 .
The film leaves the films a ₃ and b ₃ and is wound onto a roll 24 in a sterile room 29.

Therefore, according to this embodiment, the packaging materials c ₀ to _{c 3} are
Two films that are easily penetrated by the first and second electron beams
Since the object is sandwiched between a ₀ - _{a 4} and b ₀ - b ₄ and transported in a sealed state, it can be handled as a long strip-like object during electron beam irradiation treatment. It is no longer necessary to perform radiation irradiation together with other transport means such as a conveyor, and the sterilization process using electron beams can be performed completely from a practical standpoint.

In addition, in such an electron beam sterilizer,
Radiation such as X-rays generated by electron beam irradiation,
A maze is required to prevent packaging materials from leaking outside through the inlet or outlet, and as a result, for packaging materials other than continuous long strips, the transportation mechanism and maze configuration may become complicated. However, according to this embodiment, chains 7 to 10 equipped with fixing rollers G and guide blocks B are used, and the rollers G and guide blocks B can form two sheets. Since the film is conveyed while holding down the films a ₂ and b ₂ ,
Packaging material c ₂ sandwiched between two films a ₂ and b ₂
The electron beam can be transported in any direction without causing a shift in the position, and as in the above embodiment, the height of the position where the electron beam is irradiated and the position where the openings 5 and 6 are provided are significantly shifted. This makes it easy to construct a labyrinth, and leakage of X-rays and the like can be sufficiently suppressed.

Furthermore, in this embodiment, the first and second films
Since a ₀ and b ₀ can also be obtained as sterilized films a ₄ and b ₄ , they can not only be used repeatedly, but also be supplied to the market as sterilized packaging materials, increasing the operating rate of the EB equipment. can be raised. At this time, if these films a ₀ and b ₀ are polyethylene films, crosslinking progresses sequentially by electron beam irradiation, so that a modified sterilized film can be obtained by 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. Furthermore, in accordance with this, the operating positions of the side seal mechanism 12, cooling mechanism 13, seal cutter mechanism 14, etc. can be arbitrarily set according to the width of the films a ₂ and b ₂ , and it is possible to repeat the process. Films a ₂ , b ₂ whose width gradually narrows as the seal waste is separated each time they are used.
These operating positions may also be set narrower in sequence depending on the situation.

Furthermore, in the above embodiment, the side seal mechanism 1
2 to seal the first and second films a ₀ , b ₀ , but in the embodiment of the present invention, this sealing is not performed and the packaging material c ₀ is simply sealed between the films a ₀ , b _{0 .}
It may also be possible to operate it by simply inserting it between the two. According to this embodiment, the cooling mechanism 13;
There is no need to use the seal cutter mechanism 14, and naturally seal waste e is no longer generated. Therefore, even if films A ₄ and B ₄ are used repeatedly, the width dimension will not become short.
It becomes easy to use the film 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 into the electron beam irradiation chamber 3 from the sterile chamber 26 through the second opening 6, and the pressure inside the irradiation chamber 3 is kept slightly higher than atmospheric pressure, so that the film a External air is prevented from entering through the first opening 5 on the side where ₂ , b ₂ and the packaging material c ₂ are supplied, and the sterile state of the sterilized film and packaging material can be maintained even better. .

〔Effect of the invention〕

As explained above, according to the present invention, it becomes possible to handle thin plate-like packaging materials, such as carton base paper, which are divided into relatively small shapes in the same way as long strip-like packaging materials. Despite the shortcomings of the technology, it is possible to continuously and reliably sterilize divided packaging materials by electron beam irradiation, and in-line sterilization is easy. It is possible to provide an electron beam sterilizer that can perform sterilization treatment at the same time.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view showing an embodiment of the electron beam sterilizer according to the present invention, FIG. 2 is an enlarged perspective view of a part of the chain mechanism, and FIG.
Figures A and B, Figure 4 A and B, Figure 5 A and B, and Figure 6 A and B are all explanatory diagrams showing the operation of the embodiment in Figure 1, and Figure 7 A and B are packaging materials. FIG. 2 is an explanatory diagram showing the absorption state of electron beams by 1... Electron beam generator (EB device), 2... Electron beam irradiation window, 3... Electron beam irradiation room, 4... Outer wall, 5
...first opening, 6...second opening, 7,8
...Transportation chain on the supply side, 9, 10...Transportation chain on the extraction side, 11...EB reflector, 1
2...Side seal mechanism, 13...Cooling mechanism, 1
4... Seal cutter mechanism, 15-18... Chain drive motor, 19... Packaging material supply mechanism, 2
1~24...Roll, 25...Conveyor, 26~
30... Sterile room, a ₀ to a ₄ ... First film, b ₀
~ _b4 ...Second film, _c0 ~ _c3 ...Wrapping material.

Claims (1)

[Scope of Claims] 1. An electron beam sterilizer for sequentially and continuously sterilizing a plurality of relatively small-sized thin plate-like objects by electron beam irradiation, comprising first and second long strip-like films; A packaging material supply mechanism that sequentially places the thin plate-like objects to be sterilized on the first film, and a packaging material supply mechanism that sequentially places the thin plate-like objects to be sterilized on the first film, and a packaging material supply mechanism that sequentially places the second film on the first film surface on which the thin plate-like objects are placed. A roller that overlaps the thin plate-like object, an electron beam irradiation means that irradiates the thin plate-like object with a sterilizing electron beam, and the first and second films are continuously stacked with their surfaces in close contact with each other. a film transport means for transporting the film through a portion irradiated with the electron beam by the electron beam irradiation means;
a roller for separating the first and second films; and a means for taking out the sterilized thin plate-like object from between the first and second films;
First and second winding means are provided for winding the first and second films independently, and a thin plate-like object is sandwiched between the two strip-like films and conveyed, thereby continuously winding them. An electron beam sterilizer characterized in that it is configured to perform sterilization processing. 2. In claim 1, a first opening into which the first and second films in the overlapping state are carried in, and a second opening into which these films are carried out are formed. Equipped with an electron beam irradiation room,
An electron beam sterilizer characterized in that the interior of the electron beam irradiation chamber is maintained at atmospheric pressure or higher by supplying sterile air from the second opening. 3. Claim 1 provides that an electron beam reflecting plate or an electron beam reflecting block having a cooling function is provided in a portion of the electron beam irradiation section where the electron beam transmitted through the first and second films reaches. 1. An electron beam sterilization device characterized in that the device is configured so as to promote the backscattering effect of the electron beam. 4. In an electron beam sterilizer for successively sterilizing a plurality of comparatively sized thin plate-like objects by electron beam irradiation, first and second long strip-like films, and a packaging material supply mechanism that sequentially places the thin plate-like objects to be sterilized; and a roller that superimposes the second film on the first film surface on which the thin plate-like objects are placed. , a sealing means for continuously sealing both end portions of the first and second films stacked together; an electron beam irradiation means for irradiating the thin plate-like object with a sterilizing electron beam; and second
a film conveying means that continuously conveys the film through the electron beam irradiation part by the electron beam irradiation means with their surfaces in close contact with each other; a cutter means for separating the first and second films; a roller for separating the first and second films; a means for taking out the sterilized thin plate-like object from between the first and second films; and first, second, and third winding means for independently winding the second film and the separated both end portions, respectively;
An electron beam sterilizer characterized in that it is configured to carry out continuous sterilization by sandwiching and transporting a thin plate-like object between two closely spaced strip-like films. 5. In claim 4, a first opening into which the first and second films in the overlapping state are carried in, and a second opening into which these films are carried out are formed. Equipped with an electron beam irradiation room,
An electron beam sterilizer characterized in that the interior of the electron beam irradiation chamber is maintained at atmospheric pressure or higher by supplying sterile air from the second opening. 6. Claim 4 provides that an electron beam reflection plate or an electron beam reflection block having a cooling function is provided in a portion of the electron beam irradiation section where the electron beam that has passed through the first and second films reaches. What is claimed is: 1. An electron beam sterilization device, characterized in that it is configured to promote backscattering effects of electron beams. 7. The electron beam sterilizer according to claim 4, further comprising means for arbitrarily setting the operating positions of the sealing means and the cutter means in the width direction with respect to the first and second films. .