Sterilization packaging materials

Abstract

To provide a sterilization packaging material that improves recyclability and suppresses sealing defects. [Solution] The sterilization packaging material 1 comprises a gas-permeable breathable material 10 and a non-breathable material 20 bonded to a part of the breathable material 10. The breathable material 10 is made of polyolefin fibers. The non-breathable material 20 has a base material 21 including an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated on the inner surface 21b of the base material 21 and bonded to a part of the breathable material 10. The base material 21 is made of stretched polyolefin containing high-density polyethylene. The sealant layer 22 contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene.

Description

[Technical Field]

[0001] This disclosure relates to packaging materials for sterilization. [Background technology]

[0002] Medical sterile bags for storing medical supplies have been known for some time (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a medical sterilization bag in which the periphery of overlapping flexible and impermeable main sheets (non-breathable material) are tightly joined to form the bag body, and the bag body has two opposing sides and a sterile storage section between the two sides for storing medical articles. In this medical sterilization bag, an opening for removing articles from the storage section is formed in a required part of the bag body, and a flexible, breathable, and impermeable covering sheet (breathable material) is located on the outer surface of the bag body and covers the entire area of ​​the opening and the surrounding area of ​​the opening. Furthermore, in this medical sterilization bag, the periphery of the covering sheet is peelably and tightly joined to the outer surface of the bag body, and the article, the surrounding area, and the inner surface of the covering sheet facing the outer surface of the bag body are kept in a sterile state. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-286538 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the airtight materials used in conventional sterilization bags are generally composed of a laminate in which layers made of different materials such as polyethylene terephthalate and polyethylene are laminated. Therefore, with such sterilization bags, it may be difficult to recycle the sterilization bags. Also, when an airtight material made of only a single material such as polyethylene or polypropylene is used to improve recyclability, the heat resistance of the airtight material may decrease. Thus, when the heat resistance of the airtight material decreases, seal failure may occur when an air-permeable material is heat-sealed to the airtight material.

[0006] The present disclosure has been made in consideration of such points, and an object thereof is to provide a packaging material for sterilization that can improve recyclability and suppress seal failure.

Means for Solving the Problems

[0007] Embodiments of the present disclosure relate to the following [1] to [8].

[0008] [1] An air-permeable material having gas permeability, and an airtight material joined to a part of the air-permeable material, the air-permeable material is composed of polyolefin fibers, the airtight material a base material including an outer surface and an inner surface, and a sealant layer laminated on the inner surface of the base material and joined to a part of the air-permeable material, the base material is composed of a stretched polyolefin containing high-density polyethylene, the sealant layer includes linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene, a packaging material for sterilization.

[0009] [2] An air-permeable material having gas permeability, and an airtight material joined to a part of the air-permeable material, The aforementioned breathable material is composed of polyolefin fibers, The aforementioned non-breathable material is A substrate including the outer surface and the inner surface, The substrate has a sealant layer which is laminated on the inner surface and bonded to a part of the breathable material, The aforementioned substrate is composed of stretched polyolefin, The sealant layer contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene. A sterilization packaging material wherein the softening point of the outer surface of the substrate is 140°C or higher.

[0010] [3] The aforementioned substrate is a sterilization packaging material according to [2], comprising high-density polyethylene.

[0011] [4] The substrate is a sterilization packaging material according to any one of [1] to [3], comprising a plurality of layers.

[0012] [5] The sterilization packaging material according to [4], wherein the layer constituting the outer surface of the substrate has a high-density polyethylene content of 30% by mass or more and 100% by mass or less.

[0013] [6] The substrate comprises an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer, arranged in order from the outer surface to the inner surface, wherein the density of the outermost layer is higher than that of the first intermediate layer, the density of the first intermediate layer is higher than that of the second intermediate layer, the density of the innermost layer is higher than that of the third intermediate layer, and the density of the third intermediate layer is higher than that of the second intermediate layer, as described in [4] or [5].

[0014] [7] The substrate includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer, arranged in order from the outer surface to the inner surface, wherein the thickness of the outermost layer is thinner than the thickness of the first intermediate layer, the thickness of the first intermediate layer is thinner than the thickness of the second intermediate layer, the thickness of the innermost layer is thinner than the thickness of the third intermediate layer, and the thickness of the third intermediate layer is thinner than the thickness of the second intermediate layer, as described in any one of [4] to [6].

[0015] [8] The sterilization packaging material according to any one of [1] to [7], wherein the base material is made of stretched polyethylene. [Effects of the Invention]

[0016] According to this disclosure, the recyclability of sterilization packaging materials can be improved, and sealing defects can be suppressed. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a front view showing an example of a packaging bag according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view of a packaging bag according to one embodiment of the present disclosure (cross-sectional view along line II-II in Figure 1). [Figure 3A] Figure 3A is a cross-sectional view showing an example of a non-permeable material according to one embodiment of the present disclosure. [Figure 3B] Figure 3B is a cross-sectional view showing another example of a non-permeable material according to one embodiment of the present disclosure. [Figure 4A] Figure 4A is a cross-sectional view showing a method for manufacturing a sterilization packaging material according to one embodiment of the present disclosure. [Figure 4B] Figure 4B is a cross-sectional view showing a method for manufacturing a sterilization packaging material according to one embodiment of the present disclosure. [Figure 4C] Figure 4C is a cross-sectional view showing a method for manufacturing a sterilization packaging material according to one embodiment of the present disclosure. [Figure 4D]Figure 4D is a cross-sectional view showing a method for manufacturing a sterilization packaging material according to one embodiment of the present disclosure. [Figure 5] Figure 5 is a diagram illustrating the method for measuring the softening point. [Figure 6] Figure 6 is a diagram illustrating the method for measuring the softening point. [Figure 7] Figure 7 is a diagram illustrating the method for measuring the softening point. [Figure 8] Figure 8 is a diagram illustrating the method for measuring the softening point. [Modes for carrying out the invention]

[0018] An embodiment will be described below with reference to the drawings. Figures 1 to 4D show an embodiment. The following figures are schematic representations. Therefore, the size and shape of each part are exaggerated as appropriate to facilitate understanding. Furthermore, it can be modified as appropriate without departing from the technical concept. In the following figures, the same parts are denoted by the same reference numerals, and some detailed explanations may be omitted. In addition, the numerical values ​​such as dimensions and material names of each component described in this specification are examples of embodiments and are not limited to them; they can be selected and used as appropriate. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and perpendicular, will be interpreted to include not only their strict meaning but also substantially the same state.

[0019] <Sterilization packaging materials> First, an overview of the sterilization packaging material 1 according to one embodiment of the present disclosure will be described with reference to Figure 1.

[0020] As shown in Figures 1 and 2, the sterilization packaging material 1 comprises a gas-permeable breathable material 10 and a non-breathable material 20 joined to a part of the breathable material 10. Here, we will first describe the breathable material 10.

[0021] <<Breathable material>> As described above, the breathable material 10 is gas permeable. On the other hand, the breathable material 10 is impermeable to microorganisms. Therefore, as will be described later, the sterilization packaging material 1 is configured to maintain the sterile state of the instruments after sterilization. This breathable material 10 may be a nonwoven fabric. In this case, the fibers of the nonwoven fabric may be joined together by a wet, dry, direct, thermal bond, or chemical bond method. The fiber length of the nonwoven fabric is not particularly limited. The fibers of the nonwoven fabric may be short fibers or long fibers. From the viewpoint of suppressing the generation of fiber debris at the cut portion and reducing thread shedding, a nonwoven fabric formed by a thermal bond method and having long fibers can be preferably used.

[0022] The breathable material 10 is composed of polyolefin fibers. That is, general polyethylene or polyolefin such as polypropylene can be used as the raw material for the fibers forming the nonwoven fabric. This improves the recyclability of the sterilization packaging material 1, as will be described later. The breathable material 10 may also be composed of high-density polyethylene fibers among the polyolefin fibers. This improves the strength and heat resistance of the breathable material 10.

[0023] A heat-sealing agent may be applied to the surface of the fibers constituting the nonwoven fabric. In this case, the heat-sealing agent can be applied to the fiber surface by known coating methods such as gravure coating or dip coating. Furthermore, the fibers of the nonwoven fabric may be randomly intertwined. In addition, a nonwoven fabric in which thicker fibers are regularly and mesh-like overlapped and joined together may be used.

[0024] The basis weight of the nonwoven fabric is not particularly limited and depends on the required specifications, up to 5 g / m². 2 More than 100g / m 2 The following types can be used interchangeably: Nonwoven fabric with a basis weight of 5g / m². 2 As a result, the strength of the breathable material 10 can be well maintained. Also, the basis weight of the nonwoven fabric is 100 g / m². 2 The following factors can reduce manufacturing costs.

[0025] The gas permeability of the permeable material 10 may be 10 seconds / 100 mL or more, or 20 seconds / 100 mL or more. The gas permeability of the permeable material 10 shall be measured in accordance with the Gurley method of JIS P 8117:2009.

[0026] As such a breathable material 10 (nonwoven fabric), for example, Tyvek® 1073B (product number) manufactured by DuPont de Nemours, Inc. can be used.

[0027] Although not shown in the illustrations, a printed layer of characters, patterns, or barcodes may be formed on the breathable material 10. Known printing techniques may be employed. Generally, the surface of the breathable material 10, which serves as the printing surface, is rougher than the surface of the film or the printing paper. Therefore, the printed layer is preferably printed by gravure printing, letterpress printing, or flexographic printing.

[0028] Next, we will describe the non-permeable material 20.

[0029] <<Non-breathable material>> The non-permeable material 20 may be transparent or translucent. As shown in Figures 3A and 3B, the non-permeable material 20 has a base material 21 including an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated on the inner surface 21b of the base material 21 and bonded to a part of the permeable material 10. In this case, as shown in Figure 3A, the base material 21 may be composed of a single layer. Also, as shown in Figure 3B, the base material 21 may include multiple layers. In the example shown in Figure 3B, the base material 21 includes an outermost layer 23, a first intermediate layer 24, a second intermediate layer 25, a third intermediate layer 26, and an innermost layer 27, arranged in order from the outer surface 21a side to the inner surface 21b side. Of these, the outermost layer 23 may be a layer for improving the heat resistance of the base material 21. The first intermediate layer 24 may be a layer for bonding the outermost layer 23 and the second intermediate layer 25. The second intermediate layer 25 may be a layer for improving the strength of the base material 21. The third intermediate layer 26 may be a layer for bonding the innermost layer 27 and the second intermediate layer. The innermost layer 27 may be a layer for improving the heat resistance of the base material 21.

[0030] The substrate 21 and the sealant layer 22, etc., may be bonded together via an adhesive layer (not shown). The adhesive layer is an adhesive layer or thermoplastic resin layer formed to bond any two layers by lamination. As the adhesive for lamination, for example, one-component or two-component curing or non-curing type vinyl-based, (meth)acrylic-based, polyamide-based, polyester-based, polyether-based, polyurethane-based, epoxy-based, rubber-based, and others, solvent-based, water-based, or emulsion-type laminating adhesives can be used. As the coating method for the above adhesive, for example, it can be applied by direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, fontein method, transfer roll coating, or other methods. Furthermore, as the material for the thermoplastic resin layer, for example, the same material as for the sealant layer 22 can be used.

[0031] The following describes each layer that makes up the non-breathable material 20.

[0032] <<<Base material>>> The base material 21 is, for example, a layer that supports the sealant layer 22 and increases the strength of the entire sterilization packaging material 1.

[0033] The base material 21 may contain a stretched polyolefin. That is, the base material 21 contains polyolefin as a main component. In this embodiment, the base material 21 may be composed of a stretched polyolefin. Note that the "main component" refers to a component that occupies 51% by mass. In this case, the base material 21 may be composed of a stretched polyolefin containing high-density polyethylene. By containing high-density polyethylene in the base material 21, the density of the base material 21 can be increased. Thereby, the strength of the base material 21 can be increased, and the heat resistance of the base material 21 can be effectively increased. Also, the base material 21 may be composed of a stretched polyethylene film.

[0034] The base material 21 may be composed of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a mixture thereof. Also, the base material 21 may contain polypropylene or the like as a polyolefin. The base material 21 may be composed of a film or sheet of the resin as described above.

[0035] Here, low-density polyethylene has a density of 910 kg / m 3 or more and 930 kg / m 3 or less. Also, medium-density polyethylene has a density of 930 kg / m 3 or more and 942 kg / m 3 or less. Further, high-density polyethylene has a density of 942 kg / m 3 or more. Low-density polyethylene can be obtained, for example, by polymerizing ethylene at a high pressure of 1000 atmospheres or more and less than 2000 atmospheres. Medium-density polyethylene and high-density polyethylene can be obtained, for example, by polymerizing ethylene at a medium pressure or low pressure of 1 atmosphere or more and less than 1000 atmospheres.

[0036] Medium-density polyethylene and high-density polyethylene may partially contain copolymers of ethylene and α-olefins. Furthermore, even when polymerizing ethylene at medium or low pressure, medium-density or low-density polyethylene can be produced if it contains copolymers of ethylene and α-olefins. The linear low-density polyethylene described above is such a polyethylene. Linear low-density polyethylene is obtained by copolymerizing a linear polymer obtained by polymerizing ethylene at medium or low pressure with α-olefins to introduce short-chain branching. Examples of α-olefins include 1-butene (C4), 1-hexene (C6), 4-methylpentene (C6), and 1-octene (C8). The density of linear low-density polyethylene is, for example, 915 kg / m³. 3 More than 945kg / m 3 The following applies:

[0037] In the layers of the base material 21, the high-density polyethylene content in the layer constituting the outer surface 21a may be 30% by mass or more and 100% by mass or less. For example, if the base material 21 is composed of a single layer, the high-density polyethylene content in the base material 21 may be 30% by mass or more and 100% by mass or less. This increases the density of the base material 21. As a result, the strength of the base material 21 can be increased. Furthermore, because the density of the base material 21 can be increased, the heat resistance of the base material 21 can also be increased. Therefore, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 due to heat can be suppressed.

[0038] Furthermore, if the base material 21 has multiple layers, the outermost layer 23 constituting the outer surface 21a of the base material 21 may contain high-density polyethylene. By containing high-density polyethylene in the outermost layer 23, the density of the outermost layer 23 can be increased. This can increase the strength of the outermost layer 23 and effectively improve its heat resistance. The content of high-density polyethylene in the outermost layer 23 constituting the outer surface 21a of the base material 21 may be 30% by mass or more and 100% by mass or less. This can increase the density of the outermost layer 23 of the base material 21. Therefore, the strength of the base material 21 can be increased. In addition, because the density of the outermost layer 23 can be increased, the heat resistance of the outermost layer 23 can also be improved. Therefore, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 by heat can be suppressed.

[0039] In this embodiment, the outermost layer 23 may further contain medium-density polyethylene. This reduces the density difference between the outermost layer 23 and the first intermediate layer 24, which contains medium-density polyethylene as described later. As a result, a decrease in adhesive strength between the outermost layer 23 and the first intermediate layer 24 can be suppressed.

[0040] The first intermediate layer 24 may contain medium-density polyethylene and linear low-density polyethylene. This reduces the density difference between the outermost layer 23 containing medium-density polyethylene and the first intermediate layer 24. Therefore, a decrease in adhesive strength between the outermost layer 23 and the first intermediate layer 24 can be suppressed. Furthermore, the density difference between the first intermediate layer 24 and the second intermediate layer 25 containing linear low-density polyethylene, as described later, can be reduced. Therefore, a decrease in adhesive strength between the first intermediate layer 24 and the second intermediate layer 25 can be suppressed.

[0041] As mentioned above, the first intermediate layer 24 is a layer for bonding the outermost layer 23 and the second intermediate layer 25. Also, as mentioned above, the outermost layer 23 is a layer for improving the heat resistance of the substrate 21, and the second intermediate layer 25 is a layer for improving the strength of the substrate 21. For this reason, the material of the outermost layer 23 and the material of the second intermediate layer 25 may be different from each other. Even if the material of the outermost layer 23 and the material of the second intermediate layer 25 are different, the first intermediate layer 24 can improve the adhesion between the outermost layer 23 and the second intermediate layer 25. In other words, the first intermediate layer 24 can improve the adhesion between the outermost layer 23 and the second intermediate layer 25 while maintaining the heat resistance and strength of the substrate 21. Furthermore, increasing the strength of the substrate 21 improves the stretchability of the substrate 21. And by improving the stretchability of the substrate 21, the printability (ink adhesion) of the substrate 21 can be improved.

[0042] The second intermediate layer 25 may contain linear low-density polyethylene. Linear low-density polyethylene has excellent puncture resistance and stretchability. Therefore, the inclusion of linear low-density polyethylene in the second intermediate layer 25 can increase the strength of the base material 21.

[0043] The third intermediate layer 26 may contain medium-density polyethylene and linear low-density polyethylene. This reduces the density difference between the second intermediate layer 25 and the third intermediate layer 26. Therefore, a decrease in adhesive strength between the second intermediate layer 25 and the third intermediate layer 26 can be suppressed. In addition, the density difference between the third intermediate layer 26 and the innermost layer 27, which contains medium-density polyethylene as described later, can be reduced. Therefore, a decrease in adhesive strength between the third intermediate layer 26 and the innermost layer 27 can be suppressed. Furthermore, by including medium-density polyethylene and linear low-density polyethylene in the third intermediate layer 26, the composition of the third intermediate layer 26 can be made closer to the composition of the first intermediate layer 24 described above. Therefore, the film-forming properties of the substrate 21 can be improved.

[0044] As mentioned above, the third intermediate layer 26 is a layer for bonding the second intermediate layer 25 and the innermost layer 27. Also, as mentioned above, the second intermediate layer 25 is a layer for improving the strength of the substrate 21, and the innermost layer 27 is a layer for improving the heat resistance of the substrate 21. For this reason, the material of the second intermediate layer 25 and the material of the innermost layer 27 may be different from each other. Even if the material of the second intermediate layer 25 and the material of the innermost layer 27 are different, the third intermediate layer 26 can improve the adhesion between the second intermediate layer 25 and the innermost layer 27. In other words, the third intermediate layer 26 can improve the adhesion between the second intermediate layer 25 and the innermost layer 27 while maintaining the heat resistance and strength of the substrate 21. Furthermore, increasing the strength of the substrate 21 improves the stretchability of the substrate 21. And by improving the stretchability of the substrate 21, the printability (ink adhesion) of the substrate 21 can be improved.

[0045] The innermost layer 27 may contain high-density polyethylene and medium-density polyethylene. This reduces the density difference between the third intermediate layer 26 and the innermost layer 27. As a result, a decrease in adhesive strength between the third intermediate layer 26 and the innermost layer 27 can be suppressed. Furthermore, by containing high-density polyethylene and medium-density polyethylene in the innermost layer 27, the composition of the innermost layer 27 can be made closer to the composition of the outermost layer 23 described above. As a result, the film-forming properties of the substrate 21 can be improved.

[0046] If the substrate 21 has multiple layers, the density D23 of the outermost layer 23 may be higher than the density D24 of the first intermediate layer 24, and the density D24 of the first intermediate layer 24 may be higher than the density D25 of the second intermediate layer 25. Also, the density D27 of the innermost layer 27 may be higher than the density D26 of the third intermediate layer 26, and the density D26 of the third intermediate layer 26 may be higher than the density D25 of the second intermediate layer 25. In other words, the density of each layer may decrease as it approaches the second intermediate layer 25 (D23 > D24 > D25). <D26<D27)。

[0047] Thus, the density D23 of the outermost layer 23 is higher than the density D24 of the first intermediate layer 24, and the density D24 of the first intermediate layer 24 is higher than the density D25 of the second intermediate layer 25, thereby increasing the density of the outermost layer 23 of the base material 21. By arranging the density relationship of each layer in this way, the heat resistance of the outermost layer 23 of the base material 21 can be improved. For this reason, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 due to heat can be more effectively suppressed.

[0048] Furthermore, the density D27 of the innermost layer 27 is higher than the density D26 of the third intermediate layer 26, and the density D26 of the third intermediate layer 26 is higher than the density D25 of the second intermediate layer 25, thereby increasing the strength of the substrate 21. When the strength of the substrate 21 is increased in this way, the stretchability of the substrate 21 improves. And by improving the stretchability of the substrate 21, the printability (ink adhesion) of the substrate 21 can be improved.

[0049] Furthermore, the density D23 of the outermost layer 23 and the density D27 of the innermost layer 27 may be equal to each other. Also, the density D24 of the first intermediate layer 24 and the density D26 of the third intermediate layer 26 may be equal to each other. This helps to suppress warping (curling) of the base material 21.

[0050] If the substrate 21 has multiple layers, the thickness T23 of the outermost layer 23 (see Figure 3B) may be thinner than the thickness T24 of the first intermediate layer 24 (see Figure 3B), and the thickness T24 of the first intermediate layer 24 may be thinner than the thickness T25 of the second intermediate layer 25 (see Figure 3B). Also, the thickness T27 of the innermost layer 27 (see Figure 3B) may be thinner than the thickness T26 of the third intermediate layer 26 (see Figure 3B), and the thickness T26 of the third intermediate layer 26 may be thinner than the thickness T25 of the second intermediate layer 25. In other words, the thickness of each layer may increase as it approaches the second intermediate layer 25 (T23 <T24 <t25>T26 > T27). In other words, the thickness of each layer may decrease as it moves away from the second intermediate layer 25 (T23 <T24 <t25>T26 > T27).

[0051] Thus, by making the thickness T25 of the second intermediate layer 25 thicker than the thicknesses of the other layers, the strength of the base material 21 can be increased. Here, as described above, linear low-density polyethylene can be used for the second intermediate layer 25 in order to increase the strength of the base material 21. Also, as described above, linear low-density polyethylene has excellent puncture resistance and stretchability. Therefore, by increasing the thickness T25 of the second intermediate layer 25 having linear low-density polyethylene, the strength of the base material 21 can be increased.

[0052] Also, by making the thickness T23 of the outermost layer 23 thinner than the thickness T24 of the first intermediate layer 24 and making the thickness T24 of the first intermediate layer 24 thinner than the thickness T25 of the second intermediate layer 25, the heat resistance and strength of the base material 21 can be improved. That is, in the film constituting the base material 21, an anti-blocking agent (AB agent), a slip agent, or the like may be added in order to improve processing suitability. In this case, additives such as the AB agent or the slip agent are generally added to the layer constituting the surface of the film. Therefore, by making the thickness T23 of the outermost layer 23 thinner than each layer (that is, T23 < T24 < T25), the content of the additive in the film can be reduced. Also, additives such as the AB agent or the slip agent improve processing accuracy but may reduce the heat resistance and strength of the film. Therefore, by reducing the content of the additive in the film, the heat resistance and strength of the base material 21 can be improved. Note that the thickness T23 of the outermost layer 23 may be equal to the thickness T24 of the first intermediate layer 24.

[0053] Furthermore, by making the thickness T27 of the innermost layer 27 thinner than the thickness T26 of the third intermediate layer 26 and making the thickness T26 of the third intermediate layer 26 thinner than the thickness T25 of the second intermediate layer 25, the printing suitability (ink adhesion) can be improved when printing is performed on the innermost layer 27. Note that the thickness T27 of the innermost layer 27 may be equal to the thickness T26 of the third intermediate layer 26.

[0054] The thickness T23 of the outermost layer 23 and the thickness T27 of the innermost layer 27 may be equal to each other. Also, the thickness T24 of the first intermediate layer 24 and the thickness T26 of the third intermediate layer 26 may be equal to each other. The thickness T23 of the outermost layer 23 may be, for example, 0.5 μm or more and 10 μm or less. The thickness T24 of the first intermediate layer 24 may be, for example, 0.5 μm or more and 15 μm or less. The thickness T25 of the second intermediate layer 25 may be, for example, 1 μm or more and 50 μm or less. The thickness T26 of the third intermediate layer 26 may be, for example, 0.5 μm or more and 15 μm or less. The thickness T27 of the innermost layer 27 may be, for example, 0.5 μm or more and 10 μm or less.

[0055] In such a substrate 21, the softening point of the outer surface 21a of the substrate 21 may be 140°C or higher. This makes it possible to suppress damage to the outer surface 21a of the substrate 21 by heat when heat sealing the breathable material 10 and the non-breathable material 20.

[0056] The softening point of the outer surface 21a of the base material 21 can be adjusted by appropriately selecting the resin that constitutes the outer surface 21a of the base material 21. For example, by using a resin containing high-density polyethylene as the resin that constitutes the outer surface 21a of the base material 21, the softening point of the outer surface 21a of the base material 21 can be raised.

[0057] The softening point of the outer surface 21a of the substrate 21 is measured by local thermal analysis, also known as nano-TA. Details of the local thermal analysis will be explained in the examples described later.

[0058] The resin film or sheet described above may be a uniaxially stretched film or a biaxially stretched film. If it is a uniaxially stretched film, the stretching ratio is preferably 2 to 10 times, and more preferably 3 to 7 times. If it is a biaxially stretched film, the stretching ratio in one direction (e.g., the longitudinal direction (MD direction)) is preferably 2 to 10 times, and more preferably 3 to 7 times. If it is a biaxially stretched film, the stretching ratio in the other direction (e.g., the width direction (TD direction)) is preferably 2 to 10 times, and more preferably 3 to 7 times. By having a stretching ratio of 2 times or more, for example, the rigidity, strength, and heat resistance of the film can be improved. This can improve ink adhesion to the film. Also, by having a stretching ratio of 2 times or more, the transparency of the film can be improved. Furthermore, if the stretching ratio is 10 times or less, the film can be stretched effectively during the stretching process.

[0059] The thickness T of such a substrate 21 (see Figures 3A and 3B) may be, for example, 10 μm or more and 60 μm or less.

[0060] <<<Sealant layer>>> The sealant layer 22 is a layer for bonding the breathable material 10 and the non-breathable material 20 to each other. The sealant layer 22 is the innermost layer in the non-breathable material 20. This sealant layer 22 is bonded to the breathable material 10 in the sterilization packaging material 1.

[0061] The sealant layer 22 contains linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a mixture of linear low-density polyethylene and low-density polyethylene. In this embodiment, the sealant layer 22 is composed of linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a mixture of linear low-density polyethylene and low-density polyethylene. The sealant layer 22 may also be composed of a resin film or sheet as described above, or a coating film thereof.

[0062] The thickness of the sealant layer 22 may be, for example, 20 μm or more and 150 μm or less. The sealant layer 22 may consist of a single layer or multiple layers.

[0063] Referring again to Figure 1, the sterilization packaging material 1 comprises an upper edge 2, a lower edge 3 facing the upper edge 2 in a first direction d1, and a pair of side edges 4 extending from the upper edge 2 to the lower edge 3 along the first direction d1. Of these, the lower edge 3 has an opening 5 for accommodating instruments to be sterilized. This opening 5 is closed after the instruments are placed inside the sterilization packaging material 1. The first direction d1 is the transport direction of the non-permeable material 20 when manufacturing the non-permeable material 20, and is the so-called MD (Machine Direction). In the example shown in Figure 1, the upper edge 2 and the lower edge 3 extend in a second direction d2 perpendicular to the first direction d1, and the sterilization packaging material 1 has a rectangular outer shape. Although not shown, the upper edge 2 and the lower edge 3 may also extend in a direction inclined with respect to the second direction d2.

[0064] In the sterilization packaging material 1, the breathable material 10 and the non-breathable material 20 are bonded to each other at the seal portion 6. The seal portion 6 has a pair of first seal portions 7 extending along the side edge 4 of the sterilization packaging material 1, and a second seal portion 8 extending from one first seal portion 7 to the other first seal portion 7.

[0065] Of these, the second sealing portion 8 has a V-shape. In this case, the second sealing portion 8 is formed so that the tip of the V-shape faces the upper edge 2. This makes it easier for the breathable material 10 and the non-breathable material 20 to separate from each other at the tip of the V-shape in the second sealing portion 8 when opening the sterilization bag made of the sterilization packaging material 1. Note that the second sealing portion 8 is not limited to a V-shape and may have any shape such as a rectangle.

[0066] The method for forming the seal portion 6 is not particularly limited. For example, the seal portion 6 may be formed by welding the breathable material 10 and the non-breathable material 20 together by heating (heat sealing) or the like. In this case, known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, or ultrasonic sealing can be used as the heat sealing method.

[0067] The sterilization packaging material 1 shown in Figure 1 is suitably used, for example, when sterilizing medical instruments, etc., by gas sterilization with ethylene oxide gas (EOG) or steam sterilization.

[0068] As mentioned above, the opening 5 formed on the lower edge 3 is closed after the instrument is placed inside the sterilization packaging material 1. For this reason, in the illustrated example, the sterilization packaging material 1 is a so-called four-sided sealed packaging bag. However, it is not limited to this, and the sterilization packaging material 1 may be any type of sealing bag, such as a side-sealed type, a two-sided sealed type, a three-sided sealed type, an envelope-type sealed type, a center-gusseted sealed type (pillow seal type), a back-sealed tape type, a pleated sealed type, a flat-bottom sealed type, a gusseted bag type, a single-gusseted bag type, a standing pouch type, a tube bag type, or a square-bottom sealed type.

[0069] In such sterilization packaging material 1, at least 90% or more is made of the same resin system. In this case, sterilization packaging material 1 can be classified as a monomaterial material in accordance with the CEFLEX guidelines (2020) and can be suitably used to produce packaging bags (so-called monomaterial packaging containers) made of the same resin system material. Here, for example, polyethylene can be exemplified by high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene. These high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene are classified as "materials of the same resin system" in this specification. Polyolefins can also be exemplified by polyethylene and polypropylene, etc. These polyethylenes and polypropylenes are classified as "materials of the same resin system" in this specification. On the other hand, polyethylene and polyester, for example, are not classified as materials of the same resin system.

[0070] Next, the operation of the sterilization packaging material 1 according to this embodiment, which has the above configuration, will be explained. Here, first, the manufacturing method of the sterilization packaging material 1 shown in Figure 1 will be explained with reference to Figures 4A to 4D.

[0071] <Method for manufacturing sterilization packaging materials> First, prepare the breathable material 10 as shown in Figure 4A. The breathable material 10 may be a nonwoven fabric made of high-density polyethylene fibers. Although not shown in the figure, the breathable material 10 may be stored in a rolled state.

[0072] Furthermore, as shown in Figure 4B, an airtight material 20 is prepared. In this process, the resin film as the base material 21 and the resin film as the sealant layer 22 are bonded to each other, for example, by a dry lamination method. In this way, the airtight material 20 is obtained as shown in Figure 4B. Although not shown in the figures, the airtight material 20 may be stored in a rolled state.

[0073] Next, a sterilization packaging material 1 is prepared using the breathable material 10 and the non-breathable material 20.

[0074] In this case, as shown in Figure 4C, for example, the breathable material 10 is continuously unwound from a roll of breathable material 10. Similarly, the non-breathable material 20 is continuously unwound from a roll of non-breathable material 20. Then, the breathable material 10 and the non-breathable material 20 are superimposed on each other so that the sealant layer 22 of the non-breathable material 20 (see Figure 3A, etc.) faces the breathable material 10.

[0075] Next, as shown in Figure 4D, the positions corresponding to the vicinity of the pair of side edges 4 of the sterilization packaging material 1 are heat-sealed to form the first seal portion 7. At this time, a second seal portion 8 is formed at the position corresponding to each individual sterilization packaging material 1. The dashed lines (two-dot lines) shown in Figure 4D indicate the regions corresponding to each individual sterilization packaging material 1.

[0076] In this way, the sterilization packaging material 1 is obtained. Although not shown in the diagram, the sterilization packaging material 1 may be stored in a rolled state. Alternatively, the sterilization packaging material 1 may be cut into individual pieces and stored in that form.

[0077] Subsequently, the instruments to be sterilized are placed inside the sterilization packaging material 1 through an opening 5 formed in the lower edge 3 (see Figure 1) of the sterilization packaging material 1. Next, a seal is formed by heat sealing the vicinity of the lower edge 3, closing the lower edge 3 of the sterilization packaging material 1. In this way, the instruments are sealed inside the sterilization packaging material 1. Then, the instruments contained inside the sterilization packaging material 1 are sterilized by gas sterilization or steam sterilization, etc. As described above, the breathable material 10 of the sterilization packaging material 1 is impermeable to microorganisms but permeable to gas. Therefore, gas or steam enters the sterilization packaging material 1 through the breathable material 10 and sterilizes the instruments contained inside the sterilization packaging material 1. In addition, because the breathable material 10 is impermeable to microorganisms, the sterile state of the instruments after sterilization is maintained inside the sterilization packaging material 1.

[0078] After sterilizing instruments using the sterilization packaging material 1, the sterilization packaging material 1 is recycled. In this embodiment, the breathable material 10 is made of polyolefin fibers. The base material 21 of the non-breathable material 20 is made of stretched polyolefin, and the sealant layer 22 is made of linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene. Therefore, the sterilization packaging material 1 can be recycled without separating the breathable material 10 and the non-breathable material 20.

[0079] As described above, according to this embodiment, the sterilization packaging material 1 comprises a breathable material 10 that is impermeable to microorganisms but permeable to gas, and a non-breathable material 20 bonded to a part of the breathable material 10. The breathable material 10 is made of polyolefin fibers. The non-breathable material 20 has a base material 21 including an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated on the inner surface 21b of the base material 21 and bonded to the breathable material 10. The base material 21 is made of stretched polyolefin containing high-density polyethylene. Furthermore, the sealant layer 22 is made of linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene. Thus, in this embodiment, the breathable material 10 and the non-breathable material 20 are made of the same resin-based material. Therefore, the sterilization packaging material 1 can be recycled without separating the breathable material 10 and the non-breathable material 20. This improves the recyclability of the sterilization packaging material 1.

[0080] Furthermore, the base material 21 is composed of a stretched polyolefin containing high-density polyethylene. This enhances the heat resistance of the base material 21. As a result, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 due to heat can be suppressed. Consequently, the breathable material 10 and the non-breathable material 20 can be heat-sealed at a desired sealing temperature. This suppresses sealing defects between the breathable material 10 and the non-breathable material 20. Also, if the breathable material 10 is a nonwoven fabric, the surface irregularities of the breathable material 10 become larger. When heat-sealing another material to a material with large surface irregularities, the sealing pressure may need to be increased. When the sealing pressure is increased, the base material 21 may be more susceptible to heat damage during heat sealing. In contrast, in this embodiment, the heat resistance of the base material 21 can be enhanced, so even when the sealing pressure is increased, damage to the outer surface 21a of the base material 21 due to heat can be suppressed. Therefore, even when a breathable material 10 with a large surface irregularity and a non-breathable material 20 are heat-sealed, sealing defects between the breathable material 10 and the non-breathable material 20 can be suppressed.

[0081] Furthermore, according to this embodiment, the sterilization packaging material 1 comprises a breathable material 10 that is impermeable to microorganisms but permeable to gas, and a non-breathable material 20 bonded to a part of the breathable material 10. The breathable material 10 is made of polyolefin fibers. The non-breathable material 20 has a base material 21 including an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated on the inner surface 21b of the base material 21 and bonded to the breathable material 10. The base material 21 is made of stretched polyolefin. The sealant layer 22 is made of linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene. In this case as well, since the breathable material 10 and the non-breathable material 20 are made of the same resin-based material, the sterilization packaging material 1 can be recycled without separating the breathable material 10 and the non-breathable material 20. This improves the recyclability of the sterilization packaging material 1.

[0082] Furthermore, the softening point of the outer surface 21a of the base material 21 is 140°C or higher. In this case as well, the heat resistance of the base material 21 can be increased. Therefore, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 due to heat can be suppressed. As a result, sealing defects between the breathable material 10 and the non-breathable material 20 can be suppressed.

[0083] Furthermore, according to this embodiment, the base material 21 includes an outermost layer 23, a first intermediate layer 24, a second intermediate layer 25, a third intermediate layer 26, and an innermost layer 27, arranged in order from the outer surface 21a to the inner surface 21b. In addition, the density D23 of the outermost layer 23 is higher than the density D24 of the first intermediate layer 24, and the density D24 of the first intermediate layer 24 is higher than the density D25 of the second intermediate layer 25. This makes it possible to increase the density of the outermost layer 23 side of the base material 21. As a result, the heat resistance of the outermost layer 23 side of the base material 21 can be improved. Consequently, when heat sealing the breathable material 10 and the non-breathable material 20, damage to the outer surface 21a of the base material 21 due to heat can be more effectively suppressed. Furthermore, the density D27 of the innermost layer 27 is higher than the density D26 of the third intermediate layer 26, and the density D26 of the third intermediate layer 26 is higher than the density D25 of the second intermediate layer 25. This improves printability (ink adhesion) when printing is applied to the innermost layer 27.

[0084] Furthermore, according to this embodiment, the thickness T23 of the outermost layer 23 is thinner than the thickness T24 of the first intermediate layer 24, and the thickness T24 of the first intermediate layer 24 is thinner than the thickness T25 of the second intermediate layer 25. This improves the heat resistance and strength of the substrate 21. Also, the thickness T27 of the innermost layer 27 is thinner than the thickness T26 of the third intermediate layer 26, and the thickness T26 of the third intermediate layer 26 is thinner than the thickness T25 of the second intermediate layer 25. This improves printability (ink adhesion) when printing is applied to the innermost layer 27.

[0085] Furthermore, the base material 21 is composed of stretched polyethylene film. This allows for a higher proportion of polyethylene in the sterilization packaging material 1. This further improves the recyclability of the sterilization packaging material 1. [Examples]

[0086] Next, the operation of this embodiment described above will be explained in detail.

[0087] (Example A1) A non-permeable material was prepared as shown in Figure 3A. For this preparation, a polyethylene film (25 μm thick) uniaxially stretched in the first direction d1 (MD) was prepared as the base layer. This uniaxially stretched polyethylene film had a high-density polyethylene content of 100% by mass. The high-density polyethylene used was ELITE5960G (trade name) from Dowchemical (density 0.962 g / cm³). 3 (MFR 0.85g / 10min, melting point 134℃) was used (the same applies below).

[0088] In addition, a polyethylene film (50 μm thick) was prepared as a sealant layer.

[0089] Next, a non-permeable material was fabricated by bonding polyethylene films together using a dry lamination method with an adhesive layer containing an adhesive.

[0090] (Example A2) An airtight material was prepared in the same manner as in Example A1, except that the uniaxially oriented polyethylene film used as the base layer had a high-density polyethylene content of 70% by mass and a medium-density polyethylene content of 30%. The medium-density polyethylene used was Enable4002MC (trade name) from ExxonMobil (density 0.938 g / cm³). 3 (MFR 0.25g / 10min, melting point 128℃) was used (the same applies below).

[0091] (Example A3) A non-permeable material was prepared in the same manner as in Example A1, except that the uniaxially oriented polyethylene film used as the base layer had a high-density polyethylene content of 30% by mass and a medium-density polyethylene content of 70%.

[0092] (Example A4) An airtight material was prepared in the same manner as in Example A1, except that the uniaxially oriented polyethylene film used as the base layer contained 50% by mass of high-density polyethylene, 30% of medium-density polyethylene, and 20% of low-density polyethylene. The low-density polyethylene used was XP8656ML (product name) from ExxonMobil (density 0.916 g / cm³). 3 (MFR 0.50g / 10min, melting point 121℃) was used (the same applies below).

[0093] (Example A5) An airtight material was prepared in the same manner as in Example A1, except that a biaxially oriented polyethylene film was used as the base layer, and in the biaxially oriented polyethylene film, the high-density polyethylene content was 50% by mass, the medium-density polyethylene content was 30%, and the low-density polyethylene content was 20%.

[0094] (Example A6) A non-permeable material was prepared in the same manner as in Example A1, except that a biaxially oriented polypropylene film (manufactured by Toyobo Co., Ltd., P2171 (product name), 20 μm thick) was used as the base layer, and the polypropylene content of the biaxially oriented polypropylene film was 100%.

[0095] (Comparative example A) A non-permeable material was prepared in the same manner as in Example A1, except that the uniaxially oriented polyethylene film used as the base layer had a low-density polyethylene content of 100%.

[0096] (Example B1) A non-permeable material, as shown in Figure 3B, was prepared.

[0097] In this process, a resin containing 100% by mass of high-density polyethylene was prepared as the outermost layer. The density of the resin was 0.962 g / cm³. 3 That was the case.

[0098] Furthermore, a resin containing 100% by mass of high-density polyethylene was prepared as the resin constituting the first intermediate layer. The density of the resin was 0.962 g / cm³. 3 That was the case.

[0099] Furthermore, a resin containing 100% by mass of linear low-density polyethylene was prepared as the resin constituting the second intermediate layer. The density of the resin was 0.916 g / cm³. 3 That was the case.

[0100] Furthermore, a resin containing 100% by mass of high-density polyethylene was prepared as the resin constituting the third intermediate layer. The density of the resin was 0.962 g / cm³. 3 That was the case.

[0101] Furthermore, a resin with a high-density polyethylene content of 100% by mass was prepared as the resin constituting the innermost layer. The density of the resin was 0.962 g / cm³. 3 That was the case.

[0102] Next, these molten materials were co-extruded by inflation molding to produce polyethylene films. Subsequently, uniaxially stretched polyethylene films (25 μm thick) were produced by stretching in the first direction d1 (MD). At this time, the thickness of the outermost layer was 3.0 μm, the thickness of the first intermediate layer was 4.5 μm, the thickness of the second intermediate layer was 10.0 μm, the thickness of the third intermediate layer was 4.5 μm, and the thickness of the innermost layer was 3.0 μm. The thickness of each layer was measured by cutting the polyethylene film using a microtome (e.g., REM-710·SBF240W (product name) manufactured by Yamato Koki Kogyo Co., Ltd.) and then measuring the cut surface using a digital microscope (e.g., VHX-6000 (product name) manufactured by Keyence Corporation).

[0103] In addition, a polyethylene film (manufactured by Futamura Chemical Co., Ltd., product name LL-XMTN, thickness 50 μm) was prepared as a sealant layer.

[0104] Next, a non-permeable material was fabricated by laminating polyethylene films together using a dry lamination method with an adhesive layer containing adhesive. The adhesive used was a two-component polyurethane adhesive (main component: RU-004, curing agent: H-1) manufactured by Rock Paint Co., Ltd. The thickness of the adhesive layer was 3.0 μm.

[0105] (Example B2) The resin constituting the first intermediate layer is a resin containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used.

[0106] (Example B3) The outermost layer is made up of a resin with a high-density polyethylene content of 70% by mass and a medium-density polyethylene content of 30% by mass (density 0.955 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 ) was used, and the resin constituting the innermost layer is a resin with a high-density polyethylene content of 70% by mass and a medium-density polyethylene content of 30% by mass (density 0.955 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used.

[0107] (Example B4) The outermost layer is made up of a resin containing 50% by mass of high-density polyethylene, 30% by mass of medium-density polyethylene, and 20% by mass of linear low-density polyethylene (density 0.946 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 The resin used for the innermost layer consists of a resin with a high-density polyethylene content of 50% by mass, a medium-density polyethylene content of 30% by mass, and a linear low-density polyethylene content of 20% by mass (density 0.946 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used.

[0108] (Example B5) The outermost layer is made up of a resin containing 30% by mass of high-density polyethylene and 70% by mass of medium-density polyethylene (density 0.945 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 ) was used, and the resin constituting the innermost layer is a resin with a high-density polyethylene content of 30% by mass and a medium-density polyethylene content of 70% by mass (density 0.945 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used.

[0109] (Example B6) The outermost layer is made up of a resin with a high-density polyethylene content of 70% by mass and a medium-density polyethylene content of 30% by mass (density 0.955 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 ) was used, and the resin constituting the innermost layer is a resin with a high-density polyethylene content of 30% by mass and a medium-density polyethylene content of 70% by mass (density 0.945 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used.

[0110] (Example B7) The outermost layer is made up of a resin containing 30% by mass of high-density polyethylene and 70% by mass of medium-density polyethylene (density 0.945 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin (density 0.929 g / cm³) with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass. 3 ) was used, and the resin constituting the innermost layer is a resin with a high-density polyethylene content of 30% by mass and a medium-density polyethylene content of 70% by mass (density 0.945 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used. In this case, the thickness of the outermost layer was 4.5 μm, the thickness of the first intermediate layer was 5.0 μm, the thickness of the second intermediate layer was 7.5 μm, the thickness of the third intermediate layer was 4.5 μm, and the thickness of the innermost layer was 3.5 μm.

[0111] (Comparative example B) The outermost layer is made up of a resin containing 70% by mass of medium-density polyethylene and 30% by mass of linear low-density polyethylene (density 0.931 g / cm³). 3 The resin used for the first intermediate layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 ) was used, and the resin constituting the third intermediate layer is a resin with a medium-density polyethylene content of 70% by mass and a linear low-density polyethylene content of 30% by mass (density 0.931 g / cm³). 3 The resin used for the innermost layer is a resin with a medium-density polyethylene content of 60% by mass and a linear low-density polyethylene content of 40% by mass (density 0.929 g / cm³). 3 A non-permeable material was prepared in the same manner as in Example B1, except that ) was used. In this case, the thickness of the outermost layer was 4.0 μm, the thickness of the first intermediate layer was 3.5 μm, the thickness of the second intermediate layer was 10.0 μm, the thickness of the third intermediate layer was 3.5 μm, and the thickness of the innermost layer was 4.0 μm.

[0112] <Softening point measurement> Next, the softening point of the outer surface of the substrate was measured for the sterilization packaging materials of Examples A1 to Comparative Example B. The softening point of the substrate was measured by the method shown in Figures 5 to 8.

[0113] First, as shown in Figure 5, a sample S was prepared in which the outer surface 21a of the substrate 21 was exposed.

[0114] Furthermore, a nanoTA from ANASYS INSTRUMENTS was used as the softening point measurement device. A PR-EX-AN2-300-5 from ANASYS INSTRUMENTS was used as the thermal probe.

[0115] The following calibrations were performed before measurement. As standard samples, BRUKER nanoTA Calibration Samples were prepared. The standard sample holder contained polycaprolactone (softening point: 55°C), polyethylene (softening point: 116°C), and polyethylene terephthalate (softening point: 235°C), all of which have known softening points. Each standard sample was heated while a thermal probe was in contact with its surface. During heating, the thermal expansion directly beneath the thermal probe was measured, and a graph representing the Deflection (displacement) against Voltage (potential) was obtained. The measurement conditions set on the instrument were as follows: Measurement start temperature: 0.1V Measurement end temperature: 10V Heating rate: 0.5V / sec

[0116] Using the softening points of each standard sample, the graph representing the displacement of the thermal probe against potential was converted into a graph representing the displacement against temperature. Calibration (n=10) was performed in this manner.

[0117] After calibration, the softening point of the outer surface 21a of the substrate 21 was measured. The softening point was measured at five or more locations on the outer surface 21a. At this time, five or more measurement locations were selected so that the distance between adjacent locations was 5.0 μm or more. The median of the five or more measured values ​​and four measured values ​​close to the median were selected, and the arithmetic mean of these five measured values ​​was adopted as the softening point of the outer surface 21a. The median is the value that is in the middle when n (n is a natural number) measured values ​​are arranged in order of size. If n is odd, the median is the value with a size of (n+1) / 2. If n is even, the median is the average of the value with a size of n / 2 and the value with a size of (n / 2)+1.

[0118] In the measurement process, first, as shown in Figure 5, the tip 61 of the thermal probe 60 is brought into contact with the outer surface 21a of the sample S (substrate 21). The tip 61 includes an element for locally heating the sample S. The heating conditions are as follows. Measurement start temperature: 40℃ Measurement end temperature: 300℃ Heating rate: 30°C / sec

[0119] As the temperature of the tip portion 61 rises, the sample S is locally heated. As shown in Figure 6, when thermal expansion occurs in the heated portion of the sample S, the tip portion 61 is displaced upward by pressure from the expanded portion Se. As the temperature of the tip portion 61 rises further, the sample S softens due to melting or glass transition. As a result, as shown in Figure 7, the tip portion 61 enters the expanded portion Se of the sample S.

[0120] Figure 8 is a graph showing the displacement of the tip 61 in the vertical direction. The graph is also called a thermal expansion curve. The vertical axis shows the displacement of the tip 61, and the horizontal axis shows the temperature. When the sample S (substrate 21) softens, if a peak appears in the thermal expansion curve as shown in Figure 8, the temperature of the peak is adopted as the softening point Tf. If multiple peaks appear in the thermal expansion curve, the temperature of the peak appearing on the lowest temperature side is adopted as the softening point Tf. If a continuous decrease in displacement of 0.2V or more is measured from the highest displacement on the thermal expansion curve, it is considered that a peak has appeared.

[0121] <Heat resistance test> Next, heat resistance tests were conducted on the sterilization packaging materials of Examples A1 to Comparative Example B. In the heat resistance tests, a breathable material and a non-breathable material were heat-sealed, and damage to the non-breathable material at the seal was checked. The heat sealing conditions were as follows. Equipment: Heat sealer TP-701-A, manufactured by Tester Industries Co., Ltd. Temperature: 140℃ Pressure: 0.1 MPa Time: 1 second

[0122] The results are shown in Tables 1 to 3. In Table 1, "MDOPE" in the "Base Material" column refers to a uniaxially oriented polyethylene film stretched in the first direction d1 (MD). In Table 1, "BOPE" in the "Base Material" column refers to a biaxially oriented polyethylene film. Furthermore, "OPP" in the "Base Material" column refers to a biaxially oriented polypropylene film.

[0123] Furthermore, the evaluation criteria for the "Heat Resistance" column in Tables 1 and 3 are as follows: S...No damage was observed to the non-breathable material in the seal area. A...Shrinkage was observed in the non-permeable material at the seal. B...In the seal area, the non-breathable material had shrunk, causing wrinkles to form in the seal area. C...In the sealed area, the non-breathable material was torn, or part of the non-breathable material was attached to the heat sealer.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3]

[0127] As a result, as shown in Tables 1 and 3, the softening point of the outer surface of the substrate in the sterilization packaging material of Comparative Example A and the sterilization packaging material of Comparative Example B was below 140°C. In contrast, the softening point of the outer surface of the substrate in the sterilization packaging materials of Examples A1 to B7 was 140°C or higher. Therefore, it was found that the heat resistance of the substrate can be improved in the sterilization packaging material of this embodiment while increasing the proportion of the same resin-based material.

[0128] Furthermore, as shown in Tables 1 and 3, in the heat resistance test, in the sterilization packaging material of Comparative Example A and the sterilization packaging material of Comparative Example B, the non-permeable material either tore at the seal or a portion of the non-permeable material adhered to the heat sealer. In contrast, in the sterilization packaging materials of Examples A1 to B7, no tearing of the non-permeable material or adhesion of the non-permeable material to the heat sealer occurred in the heat resistance test. In particular, no damage was observed to the non-permeable material in the sterilization packaging materials of Examples A1, A6, B1, and B2. Therefore, it was found that the heat resistance of the base material can be improved in the sterilization packaging material according to this embodiment while increasing the proportion of the same resin-based material.

[0129] It is also possible to combine the multiple components disclosed in each of the above embodiments as needed. Alternatively, some components may be removed from all the components shown in each of the above embodiments. [Explanation of Symbols]

[0130] 1 Sterilization packaging materials 10 Breathable materials 20 Non-breathable materials 21 Base material 21a Exterior 21b Inner Self 22. Sealant layer 23 Outermost layer 24. First Meso-Place 25. Second Meso-Marginal Layer 26. Third Meso-Marginal Layer 27 Innermost layer

Claims

1. A sterilization packaging material having a surface and a back surface located opposite to the surface, A breathable material that has gas permeability, The system comprises a non-breathable material bonded to a portion of the aforementioned breathable material, The aforementioned surface is composed solely of the breathable material. The aforementioned breathable material is composed of polyolefin fibers, The aforementioned non-breathable material is A substrate including the outer surface and the inner surface, The substrate has a sealant layer which is laminated on the inner surface and bonded to a part of the breathable material, The substrate is composed of a stretched polyolefin containing high-density polyethylene. The sealant layer comprises linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene, and is a sterilization packaging material.

2. The sterilization packaging material according to claim 1, wherein the substrate comprises a plurality of layers.

3. The sterilization packaging material according to claim 2, wherein the layer constituting the outer surface of the substrate has a high-density polyethylene content of 30% by mass or more and 100% by mass or less.

4. The sterilization packaging material according to claim 2, wherein the substrate includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer, arranged in order from the outer surface to the inner surface, wherein the density of the outermost layer is higher than that of the first intermediate layer, the density of the first intermediate layer is higher than that of the second intermediate layer, the density of the innermost layer is higher than that of the third intermediate layer, and the density of the third intermediate layer is higher than that of the second intermediate layer.

5. The sterilization packaging material according to claim 2, wherein the substrate includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer, arranged in order from the outer surface to the inner surface, wherein the thickness of the outermost layer is thinner than the thickness of the first intermediate layer, the thickness of the first intermediate layer is thinner than the thickness of the second intermediate layer, the thickness of the innermost layer is thinner than the thickness of the third intermediate layer, and the thickness of the third intermediate layer is thinner than the thickness of the second intermediate layer.

6. The sterilization packaging material according to claim 1, wherein the base material is made of stretched polyethylene.

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