JP7844802B2 - Sterilization bag - Google Patents

Description

This invention relates to a sterile bag.

Sterilization bags are used as packaging for storing contents such as pharmaceuticals, medical supplies, various cosmetics, and food products. A sterilization bag is a bag-like structure formed by layering laminates of multiple types of resin films and joining the outer edges by heat sealing or other methods. After the contents to be sterilized are placed inside and sealed, the bag is sterilized using methods such as ethylene oxide (EO) gas or gamma ray sterilization before use.

As an example of such a sterilization bag, a sterilization packaging bag has been disclosed in which the packaging bag body is formed from two types of heat-resistant synthetic resin films, and gaps or perforations are formed to connect the inside and outside of the packaging bag body, and these gaps or perforations are covered with a filter material made by laminating nonwoven fabric and a heat-resistant plastic film with numerous small holes (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 4-21481

However, Patent Document 1 did not consider the tear-openability of sterilization packaging bags, and the sterilization packaging bags described in Patent Document 1 had the problem of being difficult to tear during use. Furthermore, packaging bags like those in Patent Document 1 require recyclability from an environmental protection perspective. Moreover, it is important for sterilization packaging bags to be easy to tear during use while maintaining a seal to ensure that the sterilized items remain sterilized until use.

One aspect of the present invention aims to provide a sterilization bag that offers improved tear-openability, maintains internal sealing, and exhibits excellent recyclability.

One embodiment of the sterile bag according to the present invention is:
A bag body comprising a sealed portion formed by laminating a laminated film having a seal layer containing at least one of low-density polyethylene and linear low-density polyethylene and a base layer containing high-density polyethylene, with the seal layers facing each other and their outer edges welded together, and a containment chamber defined by the laminated film and the sealed portion for storing the object to be sterilized, and having a slit in at least one of the laminated films that connects the laminated film,
The slit is provided so as to cover one of the laminated films from the sealing layer side, and is made of a breathable substrate containing polyethylene resin,
It is equipped with.

One embodiment of the sterilization bag according to the present invention enhances tear-openability, maintains the seal of the containment compartment, and offers excellent recyclability.

This is a plan view of a sterilization bag according to an embodiment of the present invention. This is a view from direction A-A in Figure 1. This is a schematic cross-sectional view showing an example of the structure of a laminated film. This is a perspective view showing an example of a film extrusion molding apparatus for manufacturing each layer of a laminated film. This is a plan view showing a breathable substrate. This flowchart shows an example of a method for manufacturing sterile bags. This is a perspective view of a bag-making machine used to manufacture sterile bags. This is a plan view showing an example of a sterile bag. Figure 8 is a cross-sectional view taken along the line B-B. This figure shows the test results for Example 1 and Comparative Example 1 regarding time and EO gas volume.

The embodiments of the present invention will be described in detail below. For ease of understanding, the same reference numerals are used for identical components in each drawing, and redundant explanations are omitted. Furthermore, the scale of each component in the drawings may differ from the actual scale. In this specification, the "~" indicating a numerical range means that the values before and after it are included as the lower and upper limits, respectively, unless otherwise specified.

<Sterilization bag>
A sterilization bag according to an embodiment of the present invention will now be described. Figure 1 is a plan view of the sterilization bag according to this embodiment, and Figure 2 is a view in the direction A-A of Figure 1. As shown in Figures 1 and 2, the sterilization bag 1 according to this embodiment comprises a bag body 10 into which the object to be sterilized is filled, and a breathable base material 20, both of which are made of polyethylene resin. The sterilization bag 1 is used to sterilize the object to be sterilized filled in the bag body 10 by supplying a sterilizing agent into the bag body 10.

In this embodiment, the objects to be sterilized include medical containers, medical devices, medical supplies, pharmaceuticals (drugs), nutritional supplements, food and beverages, and cosmetics. Medical containers include containers into which pharmaceuticals, animal and plant cells, tissues, and cultures are placed, and specifically include ampoules, vials, syringes, and bags. Medical devices and medical supplies include small medical instruments that can be distributed in sterile bags. Small instruments include scalpels, knives, scissors, spoons, spatulas, tweezers, catheters, syringes, injection needles, forceps, sutures, suture needles, bandages, gauze, lenses, gloves, and finger cots. Pharmaceuticals may be substances with high adsorption or permeability to general resins, such as nitroglycerin, albumin, vitamins, trace elements, and radical scavengers, or aqueous solutions containing edaravone, a pyrazolone derivative, or a pharmaceutically acceptable salt thereof. Pyrazolone derivatives may have one or more substituents, such as alkyl groups, aromatic groups, or halogen atoms, on the carbon or nitrogen atom of pyrazolone. Pyrazolone derivatives may also form salts with organic acids, inorganic acids, etc. Multiple objects of the same or different types may be simultaneously contained in the containment space.

The sterilizing agent is not particularly limited as long as it is a chemical that can be used to sterilize the object to be sterilized, such as a disinfectant or antiseptic, and is preferably one that can fill the containment space as a gas or vapor. The sterilizing agent is preferably permeable to the bag body 10 and preferably can diffuse to the outside through the bag body 10. The sterilizing agent may also decompose within the bag body _10. Examples of sterilizing agents include hydrogen peroxide ( _H₂O₂ ), ethylene oxide (EO), ozone, and organic peroxides. Examples of organic peroxides include organic peracids such as performic acid and peracetic acid. Other sterilizing agents include aldehyde-based sterilizing agents such as formaldehyde and chlorine-based sterilizing agents such as chlorine dioxide. Two or more of these sterilizing agents may be used in combination.

[Bag body]
The bag body 10 is a packaging bag (pouch) formed from a pair of overlapping laminated films 100A and 100B. The bag body 10 has a seal portion 11 formed by overlapping the pair of laminated films 100A and 100B so that they face each other and welding their outer edges together, a storage chamber 12 defined by the pair of laminated films 100 and the seal portion 11, and an opening 13 where the outer edges of the pair of laminated films 100 are not welded together. The storage chamber 12 is a space for storing the object to be sterilized. The opening 13 is an unwelded gap between the opposing laminated films 100, and may be welded or otherwise sealed after the storage chamber 12 is filled with the object to be sterilized.

The bag body 10 is a three-sided pouch, but the form of the bag body 10 is not particularly limited. It can be applied to small bags such as four-sided pouches, gusseted pouches, self-standing pouches, as well as larger bags such as inner bags for bag-in-box systems and inner bags for drums.

The laminated film 100A has a plurality of slits (cuts) 101 running through its main surface. The slits 101 may be formed in the laminated film 100B, or in both the laminated film 100A and the laminated film 100B.

The multiple slits 101 may be formed in a single row on the main surface of the laminated film 100A to form a linear perforation, or multiple slits may be formed so that linear perforations are arranged in parallel. In Figure 1, the multiple slits 101 are formed from one long side of the laminated film 100A to the other long side, but they may also be formed only in a portion of the area between the long sides of the laminated film 100A.

The length of the slit 101 and the spacing between adjacent slits 101 in the lengthwise or widthwise direction may be set to any appropriate distance depending on the size or shape of the laminated film 100A or the slit 101, and the area in which the slit 101 is formed. For example, if the length of the slit 101 is approximately 1 mm, the spacing between slits 101 in the lengthwise direction may be approximately 2 mm, and the spacing between slits 101 in the widthwise direction may be approximately 5 mm.

(Laminated film)
The laminated film 100 can be formed by overlapping and welding the seal layers of a laminated film, which has a seal layer mainly composed of at least one of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), and a base layer laminated to the seal layer and mainly composed of high-density polyethylene (HDPE), so that the seal layers face each other. The laminated film 100 may also have other layers besides the seal layer and the base layer. For example, it may include an intermediate layer between the seal layer and the base layer mainly composed of high-density polyethylene and low-density polyethylene. The laminated film 100 may have two or more of each of the seal layer, base layer, and intermediate layer.

Furthermore, the main component refers to a component whose content is 50 wt% or more, preferably 90 wt% or more, and more preferably 99 wt% or more.

Low-density polyethylene and linear low-density polyethylene refer to polyethylene with a density of approximately 0.911 g/ ^m³ to 0.940 g/ ^m³ . High-density polyethylene refers to polyethylene with a density of approximately 0.941 g/ ^m³ to 0.970 g/ ^m³ .

-Layer structure of laminated film-
The layer structure of the laminated film 100 will now be described. Figure 3 is a schematic cross-sectional view showing an example of the structure of the laminated film 100. As shown in Figure 3, the laminated film 100A may be provided by laminating a seal layer 110, an intermediate layer 120, and a base layer 130 in this order from the seal layer 110 side.

(Sealing layer)
The sealing layer 110 preferably contains at least one of low-density polyethylene and linear low-density polyethylene as its main components, is substantially composed of at least one of low-density polyethylene and linear low-density polyethylene, and is preferably composed of at least one of low-density polyethylene and linear low-density polyethylene. The sealing layer 110 preferably contains low-density polyethylene in order to enable the bag body 10 to exhibit sealing properties.

The low-density polyethylene included in the sealing layer 110 is not particularly limited as long as it has a density of approximately 0.911 g/ ^m³ to 0.925 g/ ^m³ , and any general low-density polyethylene can be used.

The linear low-density polyethylene contained in the seal layer 110 is typically copolymerized with α-olefins having four or more carbon atoms, introducing short-chain branching to create a linear molecular structure with fewer long-chain branches. Examples of α-olefins copolymerized with linear low-density polyethylene include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

Examples of linear low-density polyethylene (SLPE) included in the seal layer 110 include resins polymerized using a Ziegler-Natta catalyst and resins polymerized using a single-site catalyst. Linear low-density polyethylene polymerized using a single-site catalyst is preferred because it has a narrow molecular weight distribution and excellent mechanical properties. Examples of single-site catalysts include metallocene catalysts. Examples of metallocene catalysts include catalysts containing a metallocene compound that includes a ligand having a cyclopentadienyl skeleton and whose metal is zirconium, hafnium, etc.

Specific examples of linear low-density polyethylene included in the sealing layer 110 include the Harmolex® series manufactured by Nippon Polyethylene Co., Ltd. and the Nipolon® series manufactured by Tosoh Corporation.

The linear low-density polyethylene contained in the sealing layer 110 may be one type or two or more types.

The flexural modulus of the linear low-density polyethylene contained in the seal layer 110 is preferably 200 MPa to 500 MPa, more preferably 300 MPa to 450 MPa, and even more preferably 360 MPa to 400 MPa. If the flexural modulus of the linear low-density polyethylene contained in the seal layer 110 is within the above preferred range, the seal layer 110 will have appropriate flexibility and exhibit adhesion to the intermediate layer 120.

The flexural modulus can be measured using the method compliant with JIS K7171:2016 (ISO 178:2010).

The melt flow rate (MFR) of linear low-density polyethylene is preferably 0.1 g/10 min to 10 g/10 min, and more preferably 0.5 g/10 min to 5 g/10 min, based on measurements (230°C, 21 N load) according to JIS K 7210-1:2014 (ISO 1133-1:2011). If the MFR of the linear low-density polyethylene is within the above preferred range, when the seal layer 110 is formed by extrusion molding or the like, the extrudeability is relatively stable, and molding defects are suppressed. This makes it easier to form a stable film, and prevents molding defects such as burrs from occurring on the seal layer 110 during molding.

The melting point of linear low-density polyethylene is preferably 120°C to 135°C, and more preferably 122°C to 128°C.

The density of the linear low-density polyethylene is preferably 0.915 g/ ^cm³ to 0.940 g/ ^cm³ , and more preferably 0.920 g/ ^cm³ to 0.930 g/ ^cm³ .

The content of linear low-density polyethylene is preferably 80% to 100% by mass, and more preferably 85% to 95% by mass. If the content of linear low-density polyethylene is within the above preferred range, the seal layer 110 will have sufficient flexibility and exhibit adhesion to the intermediate layer 120.

At least a portion of the low-density polyethylene and linear low-density polyethylene contained in the sealing layer 110 may be plant-derived polyethylene obtained by polymerizing ethylene produced from plants.

Furthermore, at least a portion of the low-density polyethylene and linear low-density polyethylene contained in the seal layer 110 may be recycled polyethylene obtained by recycling polyethylene products. The recycled polyethylene may be mechanically recycled polyethylene or chemically recycled polyethylene.

The thickness of the seal layer 110 is preferably 5 μm to 50 μm, more preferably 10 μm to 30 μm, and even more preferably 8 μm to 20 μm.

(Middle class)
The intermediate layer 120 is provided between the seal layer 110 and the base layer 130, and mainly contains at least one of high-density polyethylene and low-density polyethylene, and is substantially composed of at least one of high-density polyethylene and low-density polyethylene, or may be composed of at least one of high-density polyethylene and low-density polyethylene. The intermediate layer 120 preferably contains high-density polyethylene in order to exhibit tear-openability of the laminated negative film.

As the high-density polyethylene included in the intermediate layer 120, general high-density polyethylene can be used.

The low-density polyethylene used in the intermediate layer 120 is the same as that used in the sealing layer 110, so details are omitted.

At least a portion of the high-density polyethylene and low-density polyethylene contained in the intermediate layer 120 may be plant-derived polyethylene obtained by polymerizing ethylene produced from plants.

At least a portion of the high-density polyethylene and low-density polyethylene contained in the intermediate layer 120 may be recycled polyethylene obtained by recycling polyethylene products. The recycled polyethylene may be mechanically recycled polyethylene or chemically recycled polyethylene.

The thickness of the intermediate layer 120 is preferably 3 μm to 75 μm, more preferably 5 μm to 60 μm, and even more preferably 15 μm to 45 μm.

(Base material layer)
The base layer 130 is provided on the main surface of the base layer 130 and contains high-density polyethylene as its main component, and is substantially composed of high-density polyethylene, preferably composed of high-density polyethylene. The intermediate layer 120 is preferably made of high-density polyethylene in order to allow the bag body 10 to be torn open. The high-density polyethylene used in the base layer 130 is the same as that used in the intermediate layer 120, so details are omitted.

The thickness of the base layer 130 is preferably 3 μm to 50 μm, more preferably 5 μm to 30 μm, and even more preferably 8 μm to 20 μm.

The laminated film 100A may have two or more layers of any of the layers, such as the sealing layer 110, the intermediate layer 120, and the base layer 130, or it may have other layers.

Laminated films 100A and 100B have three layers: a sealing layer 110, an intermediate layer 120, and a base layer 130. However, as described above, they may have multiple layers. For example, laminated film 100A may include five layers, with the sealing layer 110, intermediate layer 120, base layer 130, intermediate layer 120, and base layer 130 laminated in that order, or it may include seven layers, with the sealing layer 110, intermediate layer 120, base layer 130, intermediate layer 120, and base layer 130 laminated in that order.

The materials constituting each layer of the laminated film 100, namely the sealing layer 110, the intermediate layer 120, and the base layer 130, may contain various additives such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants, and anti-blocking agents, to improve the appearance of the container, stabilize its quality, and provide other necessary performance, within limits that do not impair safety and hygiene.

The method for forming each layer of the laminated film 100 is not particularly limited, but methods such as T-die molding and inflation molding can be used. When using T-die molding, after T-die molding, each layer of the laminated film 100 may be formed into a film (sheet) and then rapidly cooled with a cooling roll. When continuously forming the films of each layer of the laminated film 100, it is preferable to wind up the long molded body of each layer of film after molding, as this improves productivity.

The laminated film 100 may have other layers laminated as needed, such as a heat seal layer and a substrate. That is, there may be an adhesive layer or anchoring agent layer between each layer, or the layers may be laminated so that they are in direct contact with each other. Other layers may include a reinforcing layer, a gas barrier layer, a light-shielding layer, a printing layer, etc., and one or more layers can be selected as appropriate. The heat seal layer is the layer used for heat sealing and is placed as the innermost layer in contact with the contents of the packaging material. Heat sealing is a method of bonding by melting the heat seal layer, but the sealing method is not particularly limited and examples include hot plate sealing, ultrasonic sealing, high-frequency sealing, and impulse sealing. The substrate may be the outermost surface of the laminate opposite the heat seal layer, or it may be laminated inside the outermost surface of the other layer.

The total thickness of the laminated film 100 can be designed as appropriate. From the viewpoint of balancing required performance (e.g., transparency, flexibility, etc.) and cost (e.g., productivity, material costs, etc.), a thickness of 20 μm to 150 μm is preferred, 30 μm to 120 μm is more preferred, and 40 μm to 90 μm is even more preferred.

The thickness ratio of each layer—the sealing layer 110, the intermediate layer 120, and the base layer 130—is appropriately designed for the application of the container formed using the laminated film 100. For example, a ratio of 1:1:1 to 1:5:1 is preferred, and 1:2:1 to 1:3:1 is more preferred.

The thicknesses of the sealing layer 110, the intermediate layer 120, and the base layer 130 may be, for example, 15 μm, 30 μm, and 15 μm, respectively.

The manufacturing method for the laminated film 100 is not particularly limited. Each layer constituting the laminated film 100 may be appropriately laminated using an extrusion lamination method, a dry lamination method, a co-extrusion method, or a combination of two or more of these methods.

When manufacturing the laminated film 100, if the three layers—a sealing layer 110, a base layer 130, and an intermediate layer 120—are laminated using a co-extrusion method, as shown in Figure 3, these three layers can be laminated without the need for an adhesive layer or anchoring agent layer.

The sealing layer 110, the intermediate layer 120, and the base layer 130 can be formed, for example, by extruding and uniaxially stretching the resin film 31 constituting each layer of the sealing layer 110, the intermediate layer 120, or the base layer 130 using a film extrusion molding machine 30, as shown in Figure 4. The resin film 31 forming each of the sealing layer 110, the intermediate layer 120, and the base layer 130 is then set and fed into a laminating device (not shown), where the sealing layer 110, the intermediate layer 120, and the base layer 130 are bonded together. This forms a raw material roll of a long, continuous sheet of laminated film 100.

Furthermore, polyethylene, which serves as an interlayer adhesive layer, is extruded in a molten state and sandwiched between the resin films 31 constituting each layer of the seal layer 110, the intermediate layer 120, or the base layer 130. This causes the seal layer 110, the intermediate layer 120, or the base layer 130 to be bonded together via the adhesive layer, and the raw material for the long, continuous sheet-like laminated film 100 is laminated.

The laminated film 100 preferably has a tear strength of 26 N or less in the transport direction (MD) during its formation, more preferably 20 N or less, and even more preferably 16 N or less. A tear strength of 23 N or less improves the tear-openability of the bag body 10.

When the laminated film 100 has a thickness of 15 mm, it is preferable that the tensile strength of the laminated film 100 in the transport direction (MD) during its formation is 21 N/15 mm or more. Furthermore, it is preferable that the tensile strength of the laminated film 100 in the direction perpendicular to the transport direction (TD direction) during its formation is 15 N/15 mm or more. The tensile strength is calculated using a laminated film with a width of 15 mm square, in accordance with JIS Z 0238.

Even when the laminated film 100 has a thickness of 5 mm, it is preferable that the tensile strength of the laminated film 100 in the MD direction at the time of formation is 21 N/15 mm or more, and the tensile strength of the laminated film 100 in the TD direction is 15 N/15 mm or more.

When the laminated film 100 has a thickness of 15 mm, it is preferable that the tensile elongation of the laminated film 100 in the transport direction (MD) during its formation is 400% or more. Furthermore, it is preferable that the tensile elongation of the laminated film 100 in the direction perpendicular to the transport direction (TD direction) during its formation is 600% or more.

Even when the laminated film 100 has a thickness of 5 mm, it is preferable that the tensile elongation of the laminated film 100 in the transport direction during its formation is 400% or more, and the tensile elongation of the laminated film 100 in the TD direction is 600% or more.

[Breathable base material]
As shown in Figures 1 and 2, the breathable substrate 20 is provided on the sealing layer side of the laminated film 100A so as to cover the slit 101 of the laminated film 100A with respect to one of the laminated films 100A.

As shown in Figure 5, the breathable substrate 20 has multiple notches 21 on a side different from the sealing layer side of the laminated film 100A.

The notches 21 are preferably formed to correspond to the longitudinal direction of the breathable substrate 20.

The cut 21 may penetrate the breathable substrate 20, or it may only go partway through the breathable substrate 20.

Preferably, the cut 21 is formed with its longitudinal direction aligned with the transport direction of the laminated film 100.

The breathable substrate 20 only needs to have multiple cuts formed on its surface; for example, sterile paper can be used. Examples of sterile paper include kraft paper and glassine paper, which allow water vapor and ethylene oxide to pass through but not bacteria. Specifically, sterile paper manufactured by Tokushu Paper Co., Ltd. and Tomoegawa Paper Co., Ltd. can be used.

It is preferable that the notch 21 is formed in the same orientation as the slit 101 of the laminated film 100.

The sterilization bag 1 may be equipped with an indicator in a portion of the interlayers of the laminated film 100 that constitutes the bag body 10. A commonly used indicator can be used as the indicator. When the object to be sterilized filled in the bag body 10 is sterilized, the sterilizing agent supplied into the bag body 10 sterilizes the object, and then passes through the bag body 10, causing the indicator to change color. This allows the sterilization status, such as whether sterilization is complete, to be confirmed from the outside.

When sterilization is performed, the sterilization bag 1 is placed in the sterilization chamber of the sterilization device. The sterilizing agent present in the chamber enters the bag body 10 through the breathable substrate 20, sterilizing the items to be sterilized inside the bag body 10.

The sterilizing agent that passes through the breathable substrate 20 and enters the bag body 10 sterilizes the object to be sterilized, and then is released to the outside through the laminated film 100 that makes up the bag body 10. If an indicator is provided in a part of the interlayer of the laminated film 100 that makes up the bag body 10, the sterilizing agent that enters the bag body 10 will cause the indicator ink to change color and be released to the outside. Furthermore, since the laminated film 100 that makes up the bag body 10 is transparent, the color change of the indicator ink can be confirmed from the outside of the sterilization bag 1.

Thus, in this embodiment, the sterilization bag 1 can have its breathable base material made of polyethylene resin. This allows the bag body 10 and the breathable base material 20 of the sterilization bag 1 to be made entirely of the same polyethylene material, thereby improving tear-openability, maintaining the sealing properties of the containment compartment, and providing excellent recyclability.

In other words, as described above, the sterilization bag 1 consists of a bag body 10 formed from a laminated film 100 and a breathable base material 20. Regarding the composition of the laminated film 100, conventional sterilization bags generally consisted of a laminated film with a heat-resistant material such as polyethylene tereoflate (PET) or nylon (Ny) on the surface layer, and a sealant film such as L-LDPE, LDPE, or PP, for sealing suitability during bag manufacturing.

The inventors of this application, in developing a sterilization bag composed of a bag body made of laminated film and a breathable base material made of paper and nonwoven fabric, focused on rationalizing the manufacturing process, reducing costs, and considering environmental considerations by aiming to commercialize the product using a single material. The inventors discovered that, in manufacturing the sterilization bag 1, the laminated film 100 constituting the bag body 10 is made of polyethylene, and the breathable base material 20, which forms the breathable portion of the sterilization bag 1, is made of HDPE, thereby enabling the sterilization bag 1 to be made from a single material, polyethylene.

Furthermore, the inventors of this application have found that, in manufacturing the sterilization bag 1, the bag body 10 exhibits sealing properties. Therefore, the laminated film 100 is formed by creating a base layer on the surface of HDPE, an intermediate layer of HDPE or LDPE, and a sealing layer of LDPE or L-LDPE, thereby creating a temperature difference between the melting points of the base layer and the sealing layer, making sealing easier.

Furthermore, while L-LDPE possesses high sealing strength, it has the property of being difficult to tear by hand. The inventors of this application focused on the advantage of using LDPE as the sealing layer when considering tearability, and found that by using LDPE as the sealing layer for the laminated film 100, the bag body 10 can have sufficient sealing strength.

The sterilization bag 1 comprises a bag body 10 and a breathable base material 20. The bag body 10 is composed of a laminated film in which a sealing layer containing at least one of low-density polyethylene and linear low-density polyethylene is laminated with a base material layer containing high-density polyethylene. The bag body 10 can be easily torn by providing the base material layer containing high-density polyethylene on the surface (outside), and the airtightness of the containment chamber 12 can be maintained by providing the sealing layer containing low-density polyethylene on the back (outside). Therefore, the sterilization bag 1, by comprising the bag body 10, can improve tearability and maintain the airtightness of the containment chamber 12.

The sterilization bag 1 may include an intermediate layer 120 between the sealing layer 110 and the base layer 130 of the laminated film 100. By including high-density polyethylene or low-density polyethylene in the intermediate layer 120, the bag body 10 can be made more torn or the airtightness of the containment chamber 12 can be improved. Therefore, the sterilization bag 1 can be made more torn open and the sealing performance of the containment chamber 12 can be improved.

The sterilization bag 1 can contain high-density polyethylene in its intermediate layer 120. This allows the bag body 10 to be more reliably opened by tearing. Therefore, the sterilization bag 1 can be more reliably opened by tearing.

The sterilization bag 1 can include low-density polyethylene in its sealing layer 110. This allows the bag body 10 to further enhance the airtightness of the containment chamber 12. Therefore, the sterilization bag 1 can more reliably improve the sealing performance of the containment chamber 12.

The sterilization bag 1 can have a laminated film 100 with a thickness of 30 μm to 120 μm. This allows the bag body 10 to achieve both ease of tearing and a secure seal in the storage compartment 12, even when the laminated film 100 is thin. Therefore, the sterilization bag 1 can maintain a balance between improved tearability and the maintenance of a secure seal in the storage compartment 12.

The sterilization bag 1 can have the longitudinal direction of the slit 101 formed in one of the laminated films 100A aligned with the transport direction of the laminated film 100A. By aligning the longitudinal direction of the slit 101 with the transport direction of the laminated film 100, it can be easily formed in the laminated film 100A during the formation of the bag body 10, thereby reducing deformation of the slit 101. Therefore, the sterilization bag 1 can maintain the sealing performance of the containment chamber 12 with greater precision.

The sterilization bag 1 can have multiple notches 21 formed in the breathable base material 20 on a side different from the sealing layer side of the laminated film 100, corresponding to the longitudinal direction of the slit 101. This allows the breathable base material 20 to have substantially uniform breathability across its entire surface. Therefore, the sterilization bag 1 can maintain the sealing performance of the containment chamber 12 with greater precision.

The sterilization bag 1 can use a strip of breathable sterile paper on a breathable base material 20. This allows the sterilization bag 1 to sterilize the air entering the containment chamber 12, thereby more reliably maintaining the sterilization state of the objects to be sterilized contained in the containment chamber 12.

<Method for manufacturing sterilization bags>
An example of a method for manufacturing a sterilization bag according to an embodiment of the present invention will be described. Figure 6 is a flowchart showing an example of a method for manufacturing a sterilization bag according to this embodiment. As shown in Figure 6, in the sterilization bag according to this embodiment, a slit 101 that communicates the inside and outside is formed in one of two laminated films 100A, which consists of a seal layer 110, an intermediate layer 120, and a base layer 130, along the transport direction of the laminated film 100A (slit formation step: step S11).

Next, a breathable substrate 20 is provided on the side of the laminated film 100A facing the seal layer 110, so as to cover the slit 101 (breathable substrate coating step: step S12).

The breathable substrate 20 is joined to the seal layer 110 side of the laminated film 100A by a common joining method such as welding (heat sealing) to cover the slit 101.

Next, the two laminated films 100A and 100B are overlapped along the transport direction of the two laminated films 100A and 100B, with their sealing layer sides facing each other. The outer edges of the two laminated films 100A and 100B are then welded together, leaving unwelded openings, to form a sealed portion (welding process: step S13).

For example, as shown in Figure 7, two long, continuous sheets of laminated film raw material 41 are set in a roll state in the bag-making apparatus 40 and fed along the flow direction by the feeding mechanism 42. The transport direction (MD direction) a1 of each laminated film 100 is the flow direction of the laminated film raw material 41.

At this time, the lower laminated film roll 41 may be transported in a folded state on one side in the width direction between the two laminated film rolls 41.

Next, in the heat-seal section 43, predetermined points of the laminated film roll 41 are fused (heat-sealed), sealing three sides, and a sterilization bag 1 is formed with a breathable base material 20 provided on the sealing layer of one of the laminated films 100A. The lateral direction of the sterilization bag 1 is the direction of movement in the bag-making device 40.

The cutting section 44 separates the sterilization bags 1 one by one.

Subsequently, the sterilization bag 1 is placed into the containment chamber 12 through the opening 13 of the bag body 10, and the opening 13 is heat-sealed. Then, the sterilization bag 1 is placed in the sterilization chamber of the sterilization device. The sterilizing agent supplied to the sterilization chamber enters the bag body 10 through the breathable substrate 20, sterilizing the items to be sterilized inside the bag body 10.

According to the method for manufacturing sterilization bags, it is possible to manufacture sterilization bags 1 that have high tear-openability and maintain internal sealing properties, as described above.

The method for manufacturing the sterilization bag includes a slit formation step (step S11), allowing the slit 101 to be formed in the laminated film 100A along the transport direction of the laminated film 100A. Because the slit 101 can be formed in advance on a flat, step-free surface of the bag body 10, such as the surface of the laminated film 100A or 100B, the sterilization bag can be manufactured productively without compromising its functionality, even without sealing and fusing the breathable substrate 20 at the edges of the laminated film 100A or 100B.

For example, when manufacturing a sterilization bag by sealing a laminated film consisting of a three-layer structure (seal layer, intermediate layer, and base layer) with a gas-permeable film such as sterilization paper, as shown in Figures 8 and 9, the sterilization bag 200 is manufactured by sealing the end 211A of one laminated film 210A and the end 211B of the other laminated film 210B to the gas-permeable film 220. In such a sterilization bag 200, a step is created at the sealing portion between the laminated films 210A and 210B due to the thickness of the gas-permeable film 220, making heat sealing difficult and resulting in poor production efficiency. Furthermore, if heat sealing is not performed sufficiently, the sterilization bag 200 may not achieve sufficient sealing performance and strength.

Furthermore, when the laminated film 210 consists of a three-layer structure of a sealing layer, an intermediate layer, and a base layer, generally, low-density polyethylene or linear low-density polyethylene is used for the sealing layer, and high-density polyethylene is used for the intermediate layer and the base layer. When the laminated film 210 has such a layer configuration, the difference in melting temperature between the high-density polyethylene constituting the base layer and the low-density polyethylene or linear low-density polyethylene constituting the sealing layer is low. This makes it difficult to select optimal conditions for heat sealing, resulting in poor production efficiency of the sterilization bags 200.

In this embodiment, the method for manufacturing a sterilization bag includes a breathable substrate coating step (step S12) and a welding step (step S13). Therefore, a breathable substrate 20 is provided on the seal layer 110 side of the laminated film 100A, which has pre-formed slits, so as to cover the slits 101. The outer edges of the two laminated films 100A and 100B are then welded together to form the bag. As a result, this method allows for welding of the laminated film 100A and laminated film 100B without creating a step in the seal portion 11, thus preserving the function of the sterilization bag 1 and enabling productive manufacturing of the sterilization bag 1. Furthermore, this method makes it less likely for insufficient heat sealing to occur in the seal portion 11, resulting in a sterilization bag 1 with sufficient sealing performance and strength, providing a highly reliable sterilization bag.

As described above, sterilization bag 1, possessing the characteristics described, can be suitably used as a bag for containing and sterilizing medical containers, medical devices, medical supplies, pharmaceuticals (drugs), nutritional supplements, food and beverages, cosmetics, etc.

As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as described in the claims.

The embodiments will be described in more detail below with examples, but the embodiments are not limited to these examples.

<Example 1>
[Preparation of sterilization bags]
(Fabrication of laminated films)
Low-density polyethylene (InnoPlus LD2426H, manufactured by PTT Global Chemical Public Company Limited) was used to form the sealing layer constituting the laminated film, and high-density polyethylene (InnoPlus HD3355F, manufactured by PTT Global Chemical Public Company Limited) was used to form the intermediate layer and the base layer. Using a T-die multilayer film manufacturing machine, the low-density polyethylene, high-density polyethylene, and high-density polyethylene were extruded by co-extrusion to produce a laminated film in which the sealing layer, intermediate layer, and base layer were laminated in this order. The thicknesses of the sealing layer, intermediate layer, and base layer were 15 μm, 30 μm, and 15 μm, respectively, to produce a laminated film with a thickness of 60 μm.

(Evaluation of laminated films)
The prepared laminated film was cut to a predetermined size (width 15 mm x length 100 mm) to create rectangular test pieces 1. The laminated film was cut such that the shorter side of the test piece corresponded to the transport direction of the laminated film (MD direction), and the longer side of the test piece corresponded to the direction perpendicular to the transport direction of the laminated film (TD direction). In accordance with JIS K 7127, the tensile strength and tensile elongation of the prepared laminated film were measured to evaluate its tensile properties, and the tear strength was measured to evaluate its tearability.

- Measurement of the tensile strength of laminated films -
In accordance with JIS Z 0238, the tensile strength (unit: N/15mm) of a 15mm wide laminated film in the short direction, i.e., the transport direction of the laminated film, was calculated to evaluate the tensile properties of the laminated film. Three test specimens were prepared for each thickness, and the average of the measured values of the three specimens was used as the tensile strength of the specimen. A tensile strength of 21 N/15mm or higher was evaluated as good tensile elongation. The measurement results of the tensile strength of the laminated film are shown in Table 1.

- Measurement of tensile elongation of laminated film -
The tensile strength of the laminated film was evaluated by measuring the tensile elongation (in %) in the short direction, i.e., the direction of transport, of the laminated film using an autograph. Three test specimens were prepared for each thickness, and the average of the measurements of the three specimens was used as the tensile elongation for each specimen thickness. A tensile elongation of 400% or more was considered good. The measurement results of the tensile elongation of the laminated film are shown in Table 1.

- Measurement of tear strength of laminated film -
Tear strength (unit: N) was measured in accordance with JIS K 7128-2 (Elmendorf tear method). Seven layers of laminated film were stacked, and the tear strength (unit: N) in the short direction of the laminated film, i.e., the direction of transport of the laminated film, was measured to evaluate the tear-openability. Three test specimens were prepared, and the average value of the measurements of the three test specimens was used. If the tear strength was 26 N or less, the tear-openability was evaluated as good. The measurement results of the tear strength are shown in Table 1.

(Making the bag body)
Of the prepared laminated films, five linear perforations were formed on one of the laminated films, with 1 mm long slits (cuts) spaced approximately 2 mm apart, and five of these linear perforations were arranged in parallel at intervals of approximately 5 mm. These linear perforations were formed so as to be approximately parallel to the shorter side of one of the laminated films. Subsequently, a rectangular piece of sterile paper (high-density polyethylene nonwoven fabric, "Tyvek 2FS", manufactured by DuPont) was heat-sealed to the surface on the sealing layer side. The sterile paper was positioned so that its long side aligned with the shorter side of the laminated film. Then, using one laminated film and the other laminated film, the innermost sealing layers were overlapped, and the outer circumference of the laminate was heat-sealed except for the opening (one side on the shorter side) to create a pouch, which is the bag body with outer dimensions of 300 mm x 360 mm.

(Preparation of sterilization bags)
After trimming the outer edge of the bag body to a seal width of 5 mm, the opening of the bag body was welded to create a sterile bag. Three sterile bags were made, and the average value of the three sterile bags was used.

[Evaluation of appearance after sterilization]
Ethylene oxide (EO) gas was placed in the prepared sterilization bags as a sterilizer, and the amount of gas in the storage chamber was measured. Figure 10 shows the relationship between time and the amount of EO gas.

<Example 2>
The procedure was the same as in Example 1, except that the sealing layer was formed using linear low-density polyethylene (InnoPlus LL7410D1, manufactured by PTT Global Chemical Public Company Limited). The measurement results of the tensile strength and tensile elongation of the fabricated laminated film are shown in Table 1.

<Comparative Example 1>
In Example 1, the laminated film had no intermediate layer and consisted of a two-layer structure comprising a seal layer and a base layer. The thickness of the seal layer was 50 μm, and the seal layer was formed from PET with a thickness of 12 μm. "Tyvek (registered trademark) 1059B" was used as the sterile paper. Otherwise, the procedure was the same as in Example 1. The relationship between time and gas volume is shown in Figure 10.

As shown in Figure 10, in Example 1, the amount of EO gas in the containment chamber of the sterilization bag was approximately 1633 μg/g on day 0. While it gradually decreased over time, it remained at approximately 373 μg/g on day 2 and approximately 170 μg/g on day 3. From day 2 onward, the amount of EO gas in the containment chamber of the sterilization bag hardly decreased and was approximately the same as in Comparative Example 1.

Therefore, the sterilization bag obtained in Example 1 can be opened by tearing while maintaining the seal of the containment chamber. Thus, when used as a sterilization bag, the sterilization bag obtained in Example 1 is easy to tear, can hold the sterilizing agent inside, and can maintain stable storage for a long period of time. Therefore, it can be said that it maintains its function as a sterilization bag while allowing for easy removal and use of the items to be sterilized.

1 Sterilization bag 10 Bag body 11 Seal section 12 Storage compartment 13 Opening 20 Breathable base material 21 Notches 100, 100A, 100B Laminated film 101 Slit 110 Seal layer 120 Intermediate layer 130 Base material layer

Claims (8)

A bag body comprising a sealed portion formed by laminating a laminated film having a seal layer containing at least one of low-density polyethylene and linear low-density polyethylene and a base layer containing high-density polyethylene, with the seal layers facing each other and their outer edges welded together, and a containment chamber defined by the laminated film and the sealed portion for storing the object to be sterilized, and having a slit in at least one of the laminated films that connects the laminated film,
The slit is provided so as to cover one of the laminated films from the sealing layer side, and is made of a breathable substrate containing polyethylene resin,
Equipped with ,
The breathable substrate is a sterilization bag having a plurality of cuts formed on a side of the laminated film different from the sealing layer side, corresponding to the longitudinal direction of the slit . The sterilization bag according to claim 1, wherein the laminated film includes an intermediate layer between the sealing layer and the substrate layer, comprising at least one of high-density polyethylene and low-density polyethylene. The sterilization bag according to claim 2, wherein the intermediate layer comprises the high-density polyethylene. The sterilization bag according to any one of claims 1 to 3, wherein the sealing layer comprises the low-density polyethylene. A sterilization bag according to any one of claims 1 to 4, wherein the thickness of the laminated film is 30 μm to 120 μm. The sterilization bag according to any one of claims 1 to 5, wherein the longitudinal direction of the slit is provided along the transport direction of the laminated film. The sterilization bag according to any one of claims 1 to 6 , wherein the breathable substrate is a strip of breathable sterilization paper. A sterilization bag according to any one of claims 1 to 7 , wherein the object to be sterilized is a pharmaceutical or medical product.