Packaging material for sterilization

Abstract

[Problem] To provide a packaging material which is for sterilization, which has improved recyclability, and in which a sealing defect can be suppressed. [Solution] A packaging material 1 for sterilization comprises an air-permeable material 10 which has gas permeability and a non-air-permeable material 20 which is bonded to a part of the air-permeable material 10. The air-permeable material 10 is constituted by polyolefin fibers. The non-air-permeable material 20 has a base material 21 which includes an outer surface 21a and an inner surface 21b and a sealant layer 22 which is laminated on the inner surface 21b of the base material 21 and which is bonded to a part of the air-permeable material 10. The base material 21 is constituted by an oriented 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

Sterilization packaging material

[0001] The present disclosure relates to packaging materials for sterilization.

[0002] BACKGROUND ART Medical sterilization bags for storing medical items have been known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a medical sterilization pouch having a pouch body formed by tightly joining the peripheral edges of overlapping flexible, bacteria-impermeable main sheets (made of non-breathable material), the pouch body having opposing side surfaces and a sterile storage compartment between the side surfaces for storing medical items. This pouch also has an opening for removing the item from the storage compartment formed at a desired location on the pouch body, and a flexible, breathable, bacteria-impermeable covering sheet (made of breathable material) positioned on the outer surface of the pouch body to cover the entire open area and the area surrounding the open area. Furthermore, in this medical sterilization pouch, the peripheral edge of the covering sheet is tightly and releasably joined to the outer surface of the pouch body, maintaining the item, the peripheral area, and the inner surface of the covering sheet facing the outer surface of the pouch body in a sterile state.

[0004] Japanese Patent Application Laid-Open No. 2001-286538

[0005] However, the non-breathable materials used in conventional sterilization bags are generally composed of laminates of layers of different materials, such as polyethylene terephthalate and polyethylene. This can make such sterilization bags difficult to recycle. Furthermore, if a non-breathable material made of a single material, such as polyethylene or polypropylene, is used to improve recyclability, the heat resistance of the non-breathable material may be reduced. This reduced heat resistance of the non-breathable material can result in poor sealing when a breathable material is heat-sealed to the non-breathable material.

[0006] The present disclosure has been made in consideration of these points, and aims to provide a packaging material for sterilization that is capable of improving recyclability and suppressing sealing defects.

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

[0008] [1] A packaging material for sterilization, comprising: a breathable material having gas permeability; and a non-breathable material joined to a portion of the breathable material, wherein the breathable material is made of polyolefin fibers, and the non-breathable material has: a substrate having an outer surface and an inner surface; and a sealant layer laminated to the inner surface of the substrate and joined to a portion of the breathable material, wherein the substrate is made of oriented polyolefin containing high-density polyethylene, and the sealant layer contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene.

[0009] [2] A packaging material for sterilization, comprising: a breathable material having gas permeability; and a non-breathable material joined to a portion of the breathable material, wherein the breathable material is made of polyolefin fiber, and the non-breathable material has: a substrate having an outer surface and an inner surface; and a sealant layer laminated to the inner surface of the substrate and joined to a portion of the breathable material, wherein the substrate is made of oriented polyolefin, and the sealant layer contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene, and the softening point of the outer surface of the substrate is 140°C or higher.

[0010] [3] The packaging material for sterilization according to [2], wherein the base material contains high-density polyethylene.

[0011] [4] The packaging material for sterilization according to any one of [1] to [3], wherein the substrate includes a plurality of layers.

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

[0013] [6] The sterilization packaging material according to [4] or [5], wherein the base material includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer arranged in that order from the outer surface side to the inner surface side, and 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.

[0014] [7] The sterilization packaging material according to any one of [4] to [6], wherein the base material includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer arranged in that order from the outer surface side to the inner surface side, and 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.

[0015] [8] The packaging material for sterilization described in any one of [1] to [7], wherein the base material is made of oriented polyethylene.

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

[0017] FIG. 1 is a front view showing an example of a packaging bag according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view (cross-sectional view taken along line II-II in FIG. 1 ) of the packaging bag according to an embodiment of the present disclosure. FIG. 3A is a cross-sectional view showing an example of an air-impermeable material according to an embodiment of the present disclosure. FIG. 3B is a cross-sectional view showing another example of an air-impermeable material according to an embodiment of the present disclosure. FIG. 4A is a cross-sectional view showing a method for manufacturing a packaging material for sterilization according to an embodiment of the present disclosure. FIG. 4B is a cross-sectional view showing a method for manufacturing a packaging material for sterilization according to an embodiment of the present disclosure. FIG. 4C is a cross-sectional view showing a method for manufacturing a packaging material for sterilization according to an embodiment of the present disclosure. FIG. 4D is a cross-sectional view showing a method for manufacturing a packaging material for sterilization according to an embodiment of the present disclosure. FIG. 5 is a diagram for explaining a method for measuring a softening point. FIG. 6 is a diagram for explaining a method for measuring a softening point. FIG. 7 is a diagram for explaining a method for measuring a softening point. FIG. 8 is a diagram for explaining a method for measuring a softening point.

[0018] An embodiment will now be described with reference to the drawings. FIGS. 1 to 4D are diagrams illustrating one embodiment. The following figures are schematic illustrations. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, appropriate modifications can be made without departing from the technical concept. In the following figures, identical parts are denoted by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each component described in this specification are merely examples of an embodiment, and are not limited thereto and may be selected and used as appropriate. In this specification, terms specifying shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are interpreted not only strictly but also to include substantially the same state.

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

[0020] 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. First, the breathable material 10 will be described.

[0021] <<Breathable Material>> As described above, the breathable material 10 is gas permeable. On the other hand, the breathable material 10 does not allow microorganisms to pass through. Therefore, as will be described later, the breathable material 10 is configured to maintain the sterility of instruments after sterilization within the sterilization packaging material 1. The breathable material 10 may be a nonwoven fabric. In this case, the fibers of the nonwoven fabric may be bonded to each other 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 loss, a nonwoven fabric formed by a thermal bond method and containing long fibers may be preferably used.

[0022] The breathable material 10 is made of polyolefin fibers. That is, the raw material for the fibers forming the nonwoven fabric can be a general polyolefin such as polyethylene or polypropylene. This improves the recyclability of the sterilization packaging material 1, as will be described later. The breathable material 10 may also be made of high-density polyethylene fibers, which are 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 may be applied to the surface of the fibers by a known coating method such as gravure coating or dip coating. The fibers of the nonwoven fabric may be randomly entangled. Alternatively, a nonwoven fabric may be used in which thick fibers are regularly overlapped and bonded in a mesh pattern.

[0024] The basis weight of the nonwoven fabric is not particularly limited, and may be 5 g / m or more depending on the required specifications. ２ More than 100g / m ２ The following nonwoven fabrics may be used: ２ By setting the nonwoven fabric weight to 100 g / m or more, the strength of the breathable material 10 can be maintained satisfactorily. ２ By satisfying the following, the manufacturing cost can be reduced.

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

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

[0027] Although not shown, a printed layer of letters, designs, barcodes, etc. may be formed on the breathable material 10. A known printing method may be used. Generally, the surface of the breathable material 10 to be printed is rougher than the surface of a film or a printing paper. For this reason, the printed layer is preferably printed by gravure printing, letterpress printing, or flexographic printing.

[0028] Next, the breathable material 20 will be described.

[0029] <<Breathable Material>> The breathable material 20 may be transparent or translucent. As shown in FIGS. 3A and 3B , the breathable material 20 includes a substrate 21 having an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated to the inner surface 21b of the substrate 21 and bonded to a portion of the breathable material 10. In this case, as shown in FIG. 3A , the substrate 21 may be composed of a single layer. Alternatively, as shown in FIG. 3B , the substrate 21 may include multiple layers. In the example shown in FIG. 3B , the substrate 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 this 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 substrate 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 substrate 21. The third intermediate layer 26 may be a layer for bonding the innermost layer 27 and the second intermediate layer together. The innermost layer 27 may be a layer for improving the heat resistance of the substrate 21.

[0030] Each layer, such as the substrate 21 and the sealant layer 22, may be bonded via an adhesive layer (not shown). The adhesive layer is an adhesive layer or a thermoplastic resin layer formed to bond any two layers together by lamination. Examples of laminating adhesives that can be used include one-component or two-component curing or non-curing vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber, and other solvent-based, water-based, or emulsion-based laminating adhesives. Examples of coating methods for the adhesives include direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fountain coating, transfer roll coating, and other methods. The thermoplastic resin layer can be made of the same material as the sealant layer 22.

[0031] Each layer constituting the breathable material 20 will now be described.

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

[0033] The substrate 21 may contain a stretched polyolefin. That is, the substrate 21 contains a polyolefin as a main component. In the present embodiment, the substrate 21 may be made of a stretched polyolefin. Note that "main component" refers to a component that accounts for 51% by mass. In this case, the substrate 21 may be made of a stretched polyolefin containing high-density polyethylene. By including high-density polyethylene in the substrate 21, the density of the substrate 21 can be increased. This can increase the strength of the substrate 21, and effectively improve the heat resistance of the substrate 21. Alternatively, the substrate 21 may be made of a stretched polyethylene film.

[0034] The substrate 21 may be made of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a mixture thereof. The substrate 21 may also contain polyolefin such as polypropylene. The substrate 21 may be made of a film or sheet of any of the above resins.

[0035] Here, low density polyethylene has a density of 910 kg / m ３ More than 930kg / m ３ The medium density polyethylene has a density of 930 kg / m ３ More than 942kg / m ３ Furthermore, high density polyethylene has a density of 942 kg / m ３ The low-density polyethylene is obtained by polymerizing ethylene at a high pressure of, for example, 1,000 atmospheres or more but less than 2,000 atmospheres. The medium-density polyethylene and the high-density polyethylene are obtained by polymerizing ethylene at a medium or low pressure of, for example, 1 atmosphere or more but less than 1,000 atmospheres.

[0036] The medium-density polyethylene and high-density polyethylene may partially contain a copolymer of ethylene and an α-olefin. Even when ethylene is polymerized under medium or low pressure, medium-density or low-density polyethylene can be produced if it contains a copolymer of ethylene and an α-olefin. The linear low-density polyethylene described above is such a polyethylene. Linear low-density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene under medium or low pressure to introduce short-chain branches. Examples of α-olefins include 1-butene (C ４ ), 1-hexene (C ６ ), 4-methylpentene (C ６ ), 1-octene (C ８ The density of linear low-density polyethylene is, for example, 915 kg / m ３ More than 945kg / m ３ The following is the result.

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

[0038] Furthermore, when the substrate 21 has multiple layers, the outermost layer 23 constituting the outer surface 21a of the substrate 21 may contain high-density polyethylene. By including high-density polyethylene in the outermost layer 23, the density of the outermost layer 23 can be increased. This increases the strength of the outermost layer 23, effectively improving the heat resistance of the outermost layer 23. The high-density polyethylene content in the outermost layer 23 constituting the outer surface 21a of the substrate 21 may be 30% by mass or more and 100% by mass or less. This increases the density of the outermost layer 23 of the substrate 21. This increases the strength of the substrate 21. Furthermore, the increased density of the outermost layer 23 also increases the heat resistance of the outermost layer 23. This prevents the outer surface 21a of the substrate 21 from being damaged by heat when the breathable material 10 and the non-breathable material 20 are heat-sealed.

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

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

[0041] As described above, the first intermediate layer 24 is a layer for bonding the outermost layer 23 and the second intermediate layer 25 together. As described 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. Therefore, the material of the outermost layer 23 and the material of the second intermediate layer 25 can be different from each other. Even when the material of the outermost layer 23 and the material of the second intermediate layer 25 are different from each other, the first intermediate layer 24 can improve the adhesion between the outermost layer 23 and the second intermediate layer 25. That is, 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. Increasing the strength of the substrate 21 improves the stretchability of the substrate 21. Furthermore, improving the stretchability of the substrate 21 can improve the printability (ink adhesion) of the substrate 21.

[0042] The second intermediate layer 25 may contain linear low-density polyethylene. Linear low-density polyethylene has excellent puncture resistance and extensibility. Therefore, when the second intermediate layer 25 contains linear low-density polyethylene, the strength of the substrate 21 can be increased.

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

[0044] As described above, the third intermediate layer 26 is a layer for bonding the second intermediate layer 25 and the innermost layer 27 together. As described 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. Therefore, the material of the second intermediate layer 25 and the material of the innermost layer 27 can be different from each other. Even when the material of the second intermediate layer 25 and the material of the innermost layer 27 are different from each other, the third intermediate layer 26 can improve the adhesion between the second intermediate layer 25 and the innermost layer 27. That is, 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. Increasing the strength of the substrate 21 improves the stretchability of the substrate 21. Furthermore, improving the stretchability of the substrate 21 can improve the printability (ink adhesion) of the substrate 21.

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

[0046] When 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, which may be higher than the density D25 of the second intermediate layer 25. Furthermore, the density D27 of the innermost layer 27 may be higher than the density D26 of the third intermediate layer 26, which may be higher than the density D25 of the second intermediate layer 25. That is, the density of each layer may decrease toward the second intermediate layer 25 (D23 > D24 > D25 < D26 < D27).

[0047] In this way, 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 side of the substrate 21. By achieving this relationship in density between the layers, the heat resistance of the outermost layer 23 side of the substrate 21 can be improved. Therefore, when the breathable material 10 and the non-breathable material 20 are heat-sealed, damage to the outer surface 21a of the substrate 21 by heat can be more effectively prevented.

[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 manner, the stretchability of the substrate 21 is improved. Furthermore, the improved stretchability of the substrate 21 can improve the printability (ink adhesion) of the substrate 21.

[0049] The density D23 of the outermost layer 23 and the density D27 of the innermost layer 27 may be equal to each other. 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 can suppress warping (curling) of the substrate 21.

[0050] When the substrate 21 has multiple layers, the thickness T23 of the outermost layer 23 (see FIG. 3B ) may be thinner than the thickness T24 of the first intermediate layer 24 (see FIG. 3B ), which may be thinner than the thickness T25 of the second intermediate layer 25 (see FIG. 3B ). The thickness T27 of the innermost layer 27 (see FIG. 3B ) may be thinner than the thickness T26 of the third intermediate layer 26 (see FIG. 3B ), which may be thinner than the thickness T25 of the second intermediate layer 25. That is, the thickness of each layer may increase toward the second intermediate layer 25 (T23<T24<T25>T26>T27). In other words, the thickness of each layer may decrease away from the second intermediate layer 25 (T23<T24<T25>T26>T27).

[0051] In this way, the thickness T25 of the second intermediate layer 25 is greater than the thicknesses of the other layers, thereby increasing the strength of the substrate 21. As described above, linear low-density polyethylene may be used for the second intermediate layer 25 to increase the strength of the substrate 21. Also, as described above, linear low-density polyethylene has excellent puncture resistance and extensibility. Therefore, by increasing the thickness T25 of the second intermediate layer 25 containing linear low-density polyethylene, the strength of the substrate 21 can be increased.

[0052] Furthermore, by making the thickness T23 of the outermost layer 23 thinner than the thickness T24 of the first intermediate layer 24, which in turn is thinner than the thickness T25 of the second intermediate layer 25, the heat resistance and strength of the substrate 21 can be improved. That is, an antiblocking agent (AB agent), a slip agent, or the like may be added to the film constituting the substrate 21 to improve processability. In this case, additives such as AB agents or slip agents 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 (i.e., T23 < T24 < T25), the content of additives in the film can be reduced. Furthermore, additives such as AB agents or slip agents improve processability, but may also reduce the heat resistance and strength of the film. Therefore, by reducing the content of additives in the film, the heat resistance and strength of the substrate 21 can be improved. The thickness T23 of the outermost layer 23 may be equal to the thickness T24 of the first intermediate layer 24.

[0053] Furthermore, 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, thereby improving printability (ink adhesion) when printing is performed on the innermost layer 27. 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. 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 prevent the outer surface 21a of the substrate 21 from being damaged by heat when the breathable material 10 and the non-breathable material 20 are heat-sealed together.

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

[0057] The softening point of the outer surface 21a of the substrate 21 is measured by local thermal analysis, so-called nano-TA. Details of the local thermal analysis will be explained in the examples below.

[0058] The resin film or sheet may be a uniaxially stretched film or a biaxially stretched film. In the case of a uniaxially stretched film, the stretching ratio is preferably 2 to 10 times, and more preferably 3 to 7 times. In the case of a biaxially stretched film, the stretching ratio in one direction (e.g., the longitudinal direction (MD)) is preferably 2 to 10 times, and more preferably 3 to 7 times. Furthermore, in the case of a biaxially stretched film, the stretching ratio in the other direction (e.g., the width direction (TD)) is preferably 2 to 10 times, and more preferably 3 to 7 times. A stretching ratio of 2 times or more can improve, for example, the rigidity, strength, and heat resistance of the film. Therefore, the ink adhesion to the film can be improved. Furthermore, a stretching ratio of 2 times or more can improve the transparency of the film. Furthermore, if the stretching ratio is 10 times or less, the film can be stretched well when stretching the film.

[0059] The thickness T of the substrate 21 (see FIGS. 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 of 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 be composed of a film or sheet of the above-mentioned resin, 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 be composed of a single layer or multiple layers.

[0063] Referring again to FIG. 1 , the sterilization packaging material 1 includes 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 along the first direction d1 from the upper edge 2 to the lower edge 3. An opening 5 is formed in the lower edge 3 for accommodating an instrument to be sterilized. This opening 5 is closed after the instrument is accommodated in the sterilization packaging material 1. The first direction d1 is the conveying direction of the breathable material 20 when producing the breathable material 20, which is the so-called MD (machine direction). In the example shown in FIG. 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 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 edges 4 of the sterilization packaging material 1, and a second seal portion 8 extending from one of the first seal portions 7 to the other first seal portion 7.

[0065] Of these, the second seal portion 8 has a V-shape. In this case, the second seal 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 peel from each other at the tip of the V-shape in the second seal portion 8 when opening the sterilization bag made of the sterilization packaging material 1. Note that the second seal portion 8 is not limited to a V-shape and may have any shape, such as a rectangle.

[0066] There are no particular limitations on the method for forming the sealed portion 6. For example, the sealed 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, and ultrasonic sealing may be used as the heat sealing method.

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

[0068] As described above, the opening 5 formed in the lower edge 3 is closed after the instruments have been placed inside the sterilization packaging material 1. For this reason, in the illustrated example, the sterilization packaging material 1 is a so-called four-side sealed packaging bag. However, the sterilization packaging material 1 is not limited to this, and may be a packaging bag with any seal type, such as a side seal type, two-side seal type, three-side seal type, envelope seal type, center flared seal type (pillow seal type), back tape type, pleated seal type, flat bottom seal type, gusset bag type, one-gusset bag type, standing pouch type, tube bag type, or square bottom seal type.

[0069] In such a sterilization packaging material 1, at least 90% or more of the materials are made of the same resin system. In this case, the 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 made of the same resin system (so-called monomaterial packaging containers). Examples of polyethylene include 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. Examples of polyolefins include polyethylene and polypropylene. These polyethylenes and polypropylenes are classified as "materials of the same resin system" in this specification. On the other hand, for example, polyethylene and polyester are not classified as materials of the same resin system.

[0070] Next, the operation of the packaging material for sterilization 1 according to this embodiment having the above-described configuration will be described. First, a method for manufacturing the packaging material for sterilization 1 shown in FIG. 1 will be described with reference to FIGS. 4A to 4D.

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

[0072] Further, as shown in Fig. 4B , a non-breathable material 20 is prepared. At this time, a resin film as the substrate 21 and a resin film as the sealant layer 22 are bonded to each other by, for example, a dry lamination method. In this manner, the non-breathable material 20 is obtained as shown in Fig. 4B . Although not shown, the non-breathable material 20 may be stored in a rolled state.

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

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

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

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

[0077] Thereafter, the instruments to be sterilized are placed into the sterilization packaging material 1 through an opening 5 formed in the lower edge 3 (see FIG. 1 ) of the sterilization packaging material 1. Next, a seal is formed by heat-sealing the vicinity of the lower edge 3, and the lower edge 3 of the sterilization packaging material 1 is closed. In this manner, the instruments are enclosed within the sterilization packaging material 1. The instruments contained in the sterilization packaging material 1 are then sterilized by gas sterilization, steam sterilization, or the like. As described above, the breathable material 10 of the sterilization packaging material 1 is impermeable to microorganisms but is gas-permeable. Therefore, gas or steam enters the sterilization packaging material 1 through the breathable material 10 and sterilizes the instruments contained in the sterilization packaging material 1. Furthermore, because the breathable material 10 is impermeable to microorganisms, the sterility of the instruments is maintained within the sterilization packaging material 1 after sterilization.

[0078] After instruments are sterilized using the sterilization packaging material 1, the sterilization packaging material 1 is recycled. In this embodiment, the breathable material 10 is made of polyolefin fiber. Furthermore, the base material 21 of the non-breathable material 20 is made of oriented 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 includes a breathable material 10 that is impermeable to microorganisms but gases, and a non-breathable material 20 bonded to a portion of the breathable material 10. The breathable material 10 is made of polyolefin fibers. The non-breathable material 20 includes a substrate 21 having an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated to the inner surface 21b of the substrate 21 and bonded to the breathable material 10. The substrate 21 is made of an oriented polyolefin containing high-density polyethylene. 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. As described above, 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 substrate 21 is made of a stretched polyolefin containing high-density polyethylene. This enhances the heat resistance of the substrate 21. Therefore, when the breathable material 10 and the non-breathable material 20 are heat-sealed, the outer surface 21a of the substrate 21 is prevented from being damaged by heat. As a result, the breathable material 10 and the non-breathable material 20 can be heat-sealed at a desired sealing temperature. This reduces sealing defects between the breathable material 10 and the non-breathable material 20. Furthermore, when the breathable material 10 is a nonwoven fabric, the surface irregularities of the breathable material 10 become large. Thus, when heat-sealing another material to a material with large surface irregularities, the sealing pressure may be increased. Furthermore, increasing the sealing pressure may make the substrate 21 more susceptible to heat damage during heat sealing. In contrast, in this embodiment, the heat resistance of the substrate 21 can be enhanced, thereby reducing heat damage to the outer surface 21a of the substrate 21 even when the sealing pressure is increased. Therefore, even when the breathable material 10 and the non-breathable material 20 having large surface irregularities are heat-sealed together, poor sealing between the breathable material 10 and the non-breathable material 20 can be suppressed.

[0081] According to this embodiment, the sterilization packaging material 1 includes a breathable material 10 that is impermeable to microorganisms but gases, and a non-breathable material 20 bonded to a portion of the breathable material 10. The breathable material 10 is made of polyolefin fibers. The non-breathable material 20 includes a substrate 21 having an outer surface 21a and an inner surface 21b, and a sealant layer 22 laminated to the inner surface 21b of the substrate 21 and bonded to the breathable material 10. The substrate 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. Even in this case, since the breathable material 10 and the non-breathable material 20 are made of the same resin, 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 substrate 21 is 140°C or higher. Even in this case, the heat resistance of the substrate 21 can be improved. Therefore, when the breathable material 10 and the non-breathable material 20 are heat-sealed together, the outer surface 21a of the substrate 21 can be prevented from being damaged by heat. As a result, poor sealing between the breathable material 10 and the non-breathable material 20 can be prevented.

[0083] Furthermore, according to this embodiment, the substrate 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, which are arranged in this order from the outer surface 21a toward the inner surface 21b. The density D23 of the outermost layer 23 is higher than the density D24 of the first intermediate layer 24, which in turn is higher than the density D25 of the second intermediate layer 25. This increases the density of the outermost layer 23 side of the substrate 21. This increases the heat resistance of the outermost layer 23 side of the substrate 21. As a result, heat damage to the outer surface 21a of the substrate 21 can be more effectively prevented when the breathable material 10 and the non-breathable material 20 are heat-sealed. Furthermore, the density D27 of the innermost layer 27 is higher than the density D26 of the third intermediate layer 26, which in turn is higher than the density D25 of the second intermediate layer 25. This improves printability (ink adhesion) when printing is performed on the innermost layer 27.

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

[0085] Furthermore, the base material 21 is made of a stretched polyethylene film, which increases the proportion of polyethylene in the sterilization packaging material 1. This further improves the recyclability of the sterilization packaging material 1.

[0086] Next, the operation of the above-described embodiment will be specifically described.

[0087] (Example A1) An air-impermeable material shown in FIG. 3A was prepared. At this time, a polyethylene film (thickness 25 μm) uniaxially stretched in the first direction d1 (MD) was prepared as a base layer. This uniaxially stretched polyethylene film had a high-density polyethylene content of 100% by mass. The high-density polyethylene was ELITE 5960G (trade name) (density 0.962 g / cm) manufactured by Dow Chemical. ３ , MFR 0.85 g / 10 min, melting point 134°C) was used (the same applies below).

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

[0089] Next, the polyethylene films were bonded together by dry lamination using an adhesive layer containing an adhesive, thereby producing a non-breathable material.

[0090] (Example A2) A non-breathable material was produced in the same manner as in Example A1, except that the content of high-density polyethylene in the uniaxially stretched polyethylene film used as the substrate layer was 70% by mass, and the content of medium-density polyethylene was 30%. The medium-density polyethylene was Enable 4002MC (trade name) (density 0.938 g / cm) manufactured by ExxonMobil. ３ , MFR 0.25 g / 10 min, melting point 128°C) was used (the same applies below).

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

[0092] (Example A4) A non-breathable material was produced in the same manner as in Example A1, except that the uniaxially stretched polyethylene film used as the substrate layer contained 50% by mass of high-density polyethylene, 30% by mass of medium-density polyethylene, and 20% by mass of low-density polyethylene. The low-density polyethylene was XP8656ML (trade name) (density 0.916 g / cm) manufactured by ExxonMobil. ３ , MFR 0.50 g / 10 min, melting point 121°C) was used (the same applies below).

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

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

[0095] Comparative Example A A non-breathable material was produced in the same manner as in Example A1, except that the content of low-density polyethylene in the uniaxially stretched polyethylene film used as the base layer was 100%.

[0096] Example B1 A non-breathable material shown in FIG. 3B was prepared.

[0097] First, a resin containing 100% by mass of high-density polyethylene was prepared as the resin for the outermost layer. The density of the resin was 0.962 g / cm ３ It was.

[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 / cm ３ It was.

[0099] In addition, 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 / cm ３ It was.

[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 / cm ３ It was.

[0101] Furthermore, a resin containing 100% by mass of high-density polyethylene was prepared as the resin constituting the innermost layer. The density of the resin was 0.962 g / cm ３ It was.

[0102] Next, these melts were co-extruded by inflation molding to produce a polyethylene film. Subsequently, a uniaxially stretched polyethylene film (thickness 25 μm) was produced by stretching in the first direction d1 (MD). The outermost layer had a thickness of 3.0 μm, the first intermediate layer had a thickness of 4.5 μm, the second intermediate layer had a thickness of 10.0 μm, the third intermediate layer had a thickness of 4.5 μm, and the innermost layer had a thickness of 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] Furthermore, a polyethylene film (manufactured by Futamura Chemical Co., Ltd., LL-XMTN (trade name), thickness 50 μm) was prepared as a sealant layer.

[0104] Next, the polyethylene films were bonded together by dry lamination using an adhesive layer containing the adhesive, to produce a non-breathable material. The adhesive used was a two-component polyurethane adhesive (main agent: 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) As the resin constituting the first intermediate layer, a resin (density 0.929 g / cm 3 ) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene was used. ３ The third intermediate layer is made of a resin (density 0.929 g / cm) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene. ３ A non-breathable material was prepared in the same manner as in Example B1, except that the non-breathable material B1 was used.

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

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

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

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

[0110] (Example B7) As the resin constituting the outermost layer, a resin (density 0.945 g / cm 3 ) containing 30% by mass of high-density polyethylene and 70% by mass of medium-density polyethylene was used. ３ The resin constituting the first intermediate layer is a resin (density 0.929 g / cm) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene. ３ The third intermediate layer is made of a resin (density 0.929 g / cm) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene. ３ The resin constituting the innermost layer is a resin (density 0.945 g / cm) containing 30% by mass of high-density polyethylene and 70% by mass of medium-density polyethylene. ３ An air-impermeable material was prepared in the same manner as in Example B1, except that the outermost layer had a thickness of 4.5 μm, the first intermediate layer had a thickness of 5.0 μm, the second intermediate layer had a thickness of 7.5 μm, the third intermediate layer had a thickness of 4.5 μm, and the innermost layer had a thickness of 3.5 μm.

[0111] (Comparative Example B) The resin constituting the outermost layer was a resin (density 0.931 g / cm 3 ) containing 70% by mass of medium-density polyethylene and 30% by mass of linear low-density polyethylene. ３ The resin constituting the first intermediate layer is a resin (density 0.929 g / cm) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene.３ The third intermediate layer is made of a resin (density 0.931 g / cm) containing 70% by mass of medium-density polyethylene and 30% by mass of linear low-density polyethylene. ３ The resin constituting the innermost layer is a resin (density 0.929 g / cm) containing 60% by mass of medium-density polyethylene and 40% by mass of linear low-density polyethylene. ３ An air-impermeable material was prepared in the same manner as in Example B1, except that the outermost layer had a thickness of 4.0 μm, the first intermediate layer had a thickness of 3.5 μm, the second intermediate layer had a thickness of 10.0 μm, the third intermediate layer had a thickness of 3.5 μm, and the innermost layer had a thickness of 4.0 μm.

[0112] <Softening Point Measurement> Next, the softening points of the outer surfaces of the substrates were measured for the sterilization packaging materials of Example A1 to Comparative Example B. The softening points of the substrates were measured by the methods shown in Figs.

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

[0114] The softening point was measured using a nanoTA manufactured by ANASYS INSTRUMENTS, Inc. The thermal probe used was a PR-EX-AN2-300-5 manufactured by ANASYS INSTRUMENTS, Inc.

[0115] Prior to the measurement, the following calibration was performed. BRUKER nanoTA Calibration Samples were prepared as standard samples. Polycaprolactone (softening point: 55°C), polyethylene (softening point: 116°C), and polyethylene terephthalate (softening point: 235°C), each with a known softening point, were placed on the standard sample stage. Each standard sample was heated while being brought into contact with a thermal probe on its surface. During heating, the thermal expansion directly below the thermal probe was measured, and a graph showing deflection versus voltage was obtained. The measurement conditions set in the device were as follows: Measurement start temperature: 0.1 V Measurement end temperature: 10 V Heating rate: 0.5 V / sec

[0116] Using the softening point of each standard sample, the graph showing the displacement of the thermal probe versus potential was converted into a graph showing the displacement versus 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 measurements were performed at five or more locations on the outer surface 21a. At this time, the five or more measurement locations were determined so that the distance between adjacent locations was 5.0 μm or more. The median of the five or more measurement locations and four measurement values ​​closest to the median were selected, and the arithmetic mean of these five measurement values ​​was adopted as the softening point of the outer surface 21a. The median refers to the value located in the middle when n (n is a natural number) measurement values ​​are arranged in order of magnitude. If n is an odd number, the median is the (n+1) / 2th value. If n is an even number, the median refers to the average of the n / 2th value and the (n / 2)+1st value.

[0118] In the measurement process, first, as shown in FIG. 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°C Measurement end temperature: 300°C Heating rate: 30°C / sec

[0119] As the temperature of the tip 61 rises, the sample S is locally heated. As shown in Fig. 6, when thermal expansion occurs in the heated portion of the sample S, the tip 61 is pressed by the expanding portion Se, causing it to displace upward. As the temperature of the tip 61 further rises, the sample S softens due to melting or glass transition. As a result, the tip 61 enters the expanding portion Se of the sample S, as shown in Fig. 7.

[0120] FIG. 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 FIG. 8, the temperature of the peak is taken as the softening point Tf. If multiple peaks appear in the thermal expansion curve, the temperature of the peak that appears on the lowest temperature side is taken as the softening point Tf. If a continuous decrease in displacement of 0.2 V or more is measured from the maximum displacement in the thermal expansion curve, it is considered that a peak has appeared.

[0121] <Heat Resistance Test> Next, a heat resistance test was conducted on the sterilization packaging materials of Example A1 to Comparative Example B. In the heat resistance test, a breathable material and a non-breathable material were heat-sealed together, and damage to the non-breathable material at the sealed portion was confirmed. The heat sealing conditions were as follows: Device: Heat Sealer TP-701-A manufactured by Tester Sangyo Co., Ltd. Temperature: 140°C Pressure: 0.1 MPa Time: 1 second

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

[0123] The evaluation criteria for the "heat resistance" column in Tables 1 and 3 are as follows: S: No damage was observed in the non-breathable material in the sealed area. A: Shrinkage was observed in the non-breathable material in the sealed area. B: Shrinkage of the non-breathable material in the sealed area caused wrinkles in the sealed area. C: The non-breathable material in the sealed area was torn, or part of the non-breathable material was attached to the heat sealer.

[0124]

[0125]

[0126]

[0127] As a result, as shown in Tables 1 and 3, the softening points of the outer surfaces of the substrates in the sterilization packaging materials of Comparative Examples A and B were less than 140° C. In contrast, the softening points of the outer surfaces of the substrates in the sterilization packaging materials of Examples A1 to B7 were 140° C. or higher. Therefore, it was found that the sterilization packaging material of this embodiment can improve the heat resistance of the substrate while increasing the proportion of materials of the same resin system.

[0128] Furthermore, as shown in Tables 1 and 3, in the heat resistance test, the sterilization packaging materials of Comparative Example A and Comparative Example B had tears in the air-impermeable material at the seal or had portions of the air-impermeable material adhere to the heat sealer. In contrast, in the sterilization packaging materials of Examples A1 to B7, no tears in the air-impermeable material or adhesion of the air-impermeable material to the heat sealer occurred in the heat resistance test. In particular, no damage was observed in the air-impermeable material in the sterilization packaging materials of Examples A1, A6, B1, and B2. Therefore, it was found that the sterilization packaging material of this embodiment can improve the heat resistance of the substrate while increasing the proportion of materials based on the same resin.

[0129] It is also possible to combine the multiple components disclosed in each of the above embodiments as needed, or to delete some of the components disclosed in each of the above embodiments.

[0130] REFERENCE SIGNS LIST 1 Sterilization packaging material 10 Breathable material 20 Non-breathable material 21 Base material 21a Outer surface 21b Inner surface 22 Sealant layer 23 Outermost layer 24 First intermediate layer 25 Second intermediate layer 26 Third intermediate layer 27 Innermost layer

Claims

1. A packaging material for sterilization comprising: a breathable material having gas permeability; and a non-breathable material bonded to a portion of the breathable material, wherein the breathable material is composed of polyolefin fibers, and the non-breathable material has: a substrate having an outer surface and an inner surface; and a sealant layer laminated to the inner surface of the substrate and bonded to a portion of the breathable material, wherein the substrate is composed of an oriented polyolefin containing high-density polyethylene, and the sealant layer contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene.

2. A packaging material for sterilization comprising: a breathable material having gas permeability; and a non-breathable material bonded to a portion of the breathable material, wherein the breathable material is made of polyolefin fiber, and the non-breathable material has: a substrate having an outer surface and an inner surface; and a sealant layer laminated to the inner surface of the substrate and bonded to a portion of the breathable material, wherein the substrate is made of oriented polyolefin, and the sealant layer contains linear low-density polyethylene, low-density polyethylene, or a mixture of linear low-density polyethylene and low-density polyethylene, and the softening point of the outer surface of the substrate is 140°C or higher.

3. The sterilization packaging material of claim 2, wherein the substrate comprises high-density polyethylene.

4. The sterilization packaging material of claim 1 or 3, wherein the substrate comprises multiple layers.

5. A sterilization packaging material as described in claim 4, wherein the layer of the base material that constitutes the outer surface has a high-density polyethylene content of 30% by mass or more and 100% by mass or less.

6. The sterilization packaging material described in claim 4, 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 that order from the outer surface side to the inner surface side, and 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.

7. The sterilization packaging material described in claim 4, wherein the base material includes an outermost layer, a first intermediate layer, a second intermediate layer, a third intermediate layer, and an innermost layer arranged in that order from the outer surface side to the inner surface side, and 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.

8. The sterilization packaging material according to claim 1 or 2, wherein the substrate is made of oriented polyethylene.

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