JP2010105312A - Air-permeable packaging material and package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air-permeable packaging material having a high mechanical strength and moisture permeability sufficient as the whole packaging material, and capable of restraining raising-up or the like from being generated, and a package using the same. <P>SOLUTION: This air-permeable packaging material 1 is formed by laminating a porous nylon film 2, a reinforcing material layer 3 of network structure, and a moisture permeable film, in this order. The reinforcing material layer 3 is constituted by laminating the first fiber layer 3a faced to the reinforcing material layer 3 and comprising a plurality of the first fibers arrayed unidirectionally each other, and the second fiber layer 3b faced to the porous film 2 and comprising a plurality of the second fibers arrayed unidirectionally each other along a direction different from that of the first fibers. A cavity is formed along the second fibers in a sideway of the second fibers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a breathable packaging material and a package using the same, and more particularly to a breathable packaging material suitably used for packaging a desiccant made of silica, clay or calcium chloride.

Oxygen scavengers and desiccants are often used to prevent spoilage, alteration and deterioration of processed foods. This type of oxygen scavenger and desiccant is packaged in a breathable sachet and stored with food. The same applies to packaging of contents whose quality changes due to oxidation, moisture absorption, etc. in addition to food. As a packaging material used for packaging an oxygen scavenger and a desiccant, conventionally, a material using a breathable base material such as paper as a surface layer has been used. However, since such a surface layer cannot avoid the occurrence of fuzz and paper dust, in recent years, a perforated film using nylon, polypropylene, or the like as the surface layer has been used (for example, see Patent Documents 1 and 2). In Patent Documents 1 and 2, in order to ensure mechanical strength and air permeability as a whole packaging material, a reinforcing material layer made of a nonwoven fabric is laminated on the back surface of the base material, and a permeable film is further provided under the reinforcing material layer. A breathable packaging material having a three-layer structure in which is laminated is disclosed.
JP 2004-216701 A JP 2003-340950 A

  Conventionally, quick lime, silica, clay, calcium chloride, and the like are used as the desiccant in the case of producing a package in which the desiccant is enclosed. Of these, quick lime is excellent in water absorption at low humidity, but due to the strong alkali, the influence on the human body is unavoidable. In recent years, desiccants made of silica, clay or calcium chloride that do not have such problems have been used. Widely used. In order to exhibit the ability of these desiccants, it is necessary to ensure sufficient moisture permeability of the package. However, the breathable packaging materials disclosed in Patent Documents 1 and 2 do not have sufficient moisture permeability.

  An object of the present invention is to provide a breathable packaging material having mechanical strength and sufficient moisture permeability as a whole packaging material and capable of suppressing the occurrence of fuzz and the like, and a package using the same. Objective.

  In the breathable packaging material according to one embodiment of the present invention, a perforated film made of nylon, a reinforcing material layer having a network structure, and a porous moisture-permeable film are laminated in this order. The reinforcing material layer faces the reinforcing material layer and faces the perforated film in a direction different from the first fiber, the first fiber layer including a plurality of first fibers arranged in the same direction. And the 2nd fiber layer which consists of a some 2nd fiber arranged in the mutually same direction is laminated | stacked and comprised. A gap is formed along the second fiber on the side of the second fiber.

  By forming a void along the second fiber on the side of the second fiber, it becomes possible to secure a flow path of water vapor entering from the perforated film. That is, when water vapor enters from the perforated film, it continues to flow into the second fiber layer facing the perforated film, but there is a large space due to voids on the side of each second fiber constituting the second fiber layer. Since it is formed, it becomes easy to ensure the flow path of water vapor. As a result, it becomes easy to ensure a desired moisture permeability.

   FIG. 1 is a schematic view of a breathable packaging material according to an embodiment of the present invention, in which FIG. 1 (a) is a cross-sectional view and FIG. 1 (b) is a top view. As shown to Fig.1 (a), the air permeable packaging material 1 of this embodiment is the porous film 2 made from nylon, the reinforcing material layer 3 of a network structure, and the porous moisture-permeable film 4 in this order. Are stacked. Printing (not shown) is applied to the back surface 2 a facing the reinforcing material layer 3 of the perforated film 2. The perforated film 2, the reinforcing material layer 3, and the moisture permeable film 4 can be joined together by a thermocompression bonding method. This breathable packaging material 1 is formed into a bag shape, and packaged by storing functional articles such as oxygen scavenger, desiccant, exothermic agent, moisture absorbent, deodorant, insect repellent, dehumidifier, and fragrance inside The body can be formed. In FIG. 2, sectional drawing of a package is shown. When making the package 6 from the breathable packaging material 1, the moisture-permeable film 4 is used as a heat seal layer. Specifically, the breathable packaging material 1 is folded into a bag shape with the moisture permeable film 4 facing inside so that both ends of the moisture permeable film 4 are opposed to each other, the functional article 5 is wrapped, and the peripheral portion is formed by a hot press method. Heat seal. Below, each layer which comprises the air permeable packaging material 1 is demonstrated in detail.

(1) Perforated film An unstretched nylon film is used for the perforated film 2. In one example, the non-stretched nylon film has a thickness of about 15 μm, and pores 7 are formed at regular intervals as shown in FIG. Specific examples of perforated film 2 include “Bonyl” (trade name) manufactured by Teijin Limited, “Harden” (trade name) manufactured by Toyobo Co., Ltd., and “Emblem” manufactured by Unitika Ltd. (Product name).

  The perforated film 2 constitutes the outermost layer of the package 6 as described above. Therefore, unlike the conventional case where paper is used for the outermost layer, fuzz and paper dust are not generated, and it is hygienic even if the package is stored together with food.

  Printing can be performed on the back surface 2a of the perforated film 2 (the surface facing the reinforcing material layer 3). Since the perforated film 2 is superior in surface smoothness compared to paper, clear printing is possible. Moreover, since the perforated film 2 consists of a transparent unstretched nylon film, printing information can be seen clearly also from the surface side. Since printing is performed on the back surface 2a of the perforated film 2, the printing part is not exposed on the surface of the package, and the printing ink does not come into contact with the food even when the package is stored together with the food. Therefore, for printing, ink that is generally used for printing on packaging materials that conforms to the NL regulations of “Voluntary Regulations for Printing Inks for Food Packaging Materials” established by the Federation of Printing Ink Industries can be used. As a result, there is no need to use a special ink as in the prior art, and printing with an arbitrary color tone can be performed using an ink having excellent adhesion to the perforated film 2. Moreover, since cheap ink can be used, the breathable packaging material 1 can be manufactured at low cost.

(2) Reinforcing Material Layer FIG. 3 shows a partial perspective view of the reinforcing material layer. The figure (a) is a perspective view, The figure (b) is the top view seen from the direction of a perforated film. The reinforcing material layer 3 is arranged in the same direction y in the first fiber layer 3a composed of a plurality of first fibers 11 arranged in the same direction x, and in the direction y substantially orthogonal to the first fibers 11. The second fiber layer 3b composed of the plurality of second fibers 12 is laminated. The first fiber layer 3 a faces the moisture permeable film 4, and the second fiber layer 3 b faces the perforated film 2. The thickness h of the reinforcing material layer 3 at the intersection P between the first fiber 11 of the first fiber layer 3a and the second fiber 12 of the second fiber layer 3b is 120 μm or more. See also FIG. 5 for the thickness h of the reinforcement layer. The second fiber layer 3b does not need to be orthogonal to the first fiber layer 3a, but is oriented at least in a different direction, and the first fiber layer 3a and the second fiber layer 3b are stacked. Should just be formed. The thickness of the reinforcing material layer 3 is made larger than that of the prior art. As a result, a gap 8 is formed along the second fiber on the side of the second fiber (see FIG. 5).

  In the present embodiment, the reinforcing material layer 3 is formed by laminating a first fiber layer 3a in which the first fibers 11 are arranged in the vertical direction and a second fiber layer 3b in which the second fibers 12 are arranged in the horizontal direction. It is a split fiber nonwoven fabric. The second fiber layer 3b is joined to the perforated film 2 by a thermocompression bonding method. In the present specification, the “longitudinal direction” means a machine direction, that is, a feeding direction in manufacturing a nonwoven fabric, a web, a laminate, etc., and “transverse direction” means a direction perpendicular to the longitudinal direction, that is, a nonwoven fabric, The width direction of a web, a laminated body, etc. is meant.

  As the reinforcing material layer 3, various materials can be used as long as they have moisture permeability and can reinforce the perforated film 2. In addition to the split fiber nonwoven fabric, a lattice network such as a net-like material can be used. The body can be used.

  A split fiber nonwoven fabric is formed by forming a large number of slits in a polyolefin resin film and stretching it in the direction of the slit, and then extending the film in a direction perpendicular to the stretching direction, or unidirectionally forming a polyolefin resin film in one direction. After forming a large number of slits parallel to the stretching direction, the film is spread in a direction perpendicular to the stretching direction to form a mesh film, and the two mesh films are overlapped so that the stretching directions are orthogonal to each other. It is a nonwoven fabric obtained by heat bonding.

  Thus, since the split fiber nonwoven fabric is laminated with two reticulated films so that their stretching directions are orthogonal, the strength balance in the vertical and horizontal directions is excellent. Moreover, since the split fiber nonwoven fabric has a network structure in which the slit-formed portion is a ventilation portion, it has sufficient air permeability. A typical example of the split fiber non-woven fabric is Walif (trade name, manufactured by Nippon Petroleum Co., Ltd.).

  When a split fiber nonwoven fabric is used for the reinforcing material layer 3, a film having a three-layer structure of a low melting point resin layer / a high melting point resin layer / a low melting point resin layer suitable for thermal bonding is preferable as the film used for the production thereof. . In particular, considering the adhesiveness with the moisture permeable film 4, it is preferable that the resin constituting the base film of the split fiber nonwoven fabric is a resin of the same quality as the moisture permeable film 4. For example, when the moisture-permeable film 4 is made of polyethylene, it is preferable that the low-melting resin layer is made of low-density polyethylene and the high-melting resin layer is made of high-density polyethylene. The draw ratio of the film is preferably 1.1 to 15 times. When the draw ratio is less than 1.1 times, the mechanical strength of the nonwoven fabric is not sufficient. On the other hand, when the draw ratio exceeds 15 times, it is difficult to stretch by a usual method, and an expensive apparatus is required.

  As the lattice network, a net-like material made of polyethylene or polypropylene can be used in addition to the split fiber nonwoven fabric. Net-like products include Sofsui Film Co., Ltd. Sofnet, Sofcross (trade name), Kurabo Industries Kurenet (trade name), Global Netting Solutions Co. net, Thermanet ( Product name). In addition, Meltac (trade name) manufactured by Ebara Industries Co., Ltd., which is a woven fabric, can be used.

(3) Moisture permeable film A porous moisture permeable film is a microporous film which consists of polyolefin resin. The moisture permeable film 4 is formed by stretching a resin composition made of a thermoplastic resin containing a filler to form micropores in the resin composition and imparting air permeability.

  The breathable packaging material 1 is required to have an appropriate moisture permeability necessary for the functional article 5 accommodated therein to function. This moisture permeability varies depending on the application, such as the type of functional article and the size of the package, and is not particularly limited. However, when used for a desiccant made of silica, clay or calcium chloride, the moisture permeability is sufficient. Desired. In particular, in applications for desiccants made of calcium chloride, which may melt and flow out when absorbing water having a water retention capacity or more, it is also required that the desiccant does not leak.

  Examples of the thermoplastic resin used for the moisture permeable film 4 include α-olefin homopolymers such as low-density polyethylene, high-density polyethylene, polypropylene, and polybutene, and copolymers of ethylene and at least one α-olefin having 3 to 18 carbon atoms. Polymer, Copolymer of propylene and ethylene and / or butene-1, Copolymerization of ethylene with organic carboxylic acid derivative having ethylenically unsaturated bond such as vinyl acetate and / or acrylate ester / methacrylate ester Examples include coalescence.

  Among these, in particular, a copolymer of ethylene and at least one α-olefin having 3 to 8 carbon atoms is preferable from the viewpoint of strength at the time of blending the filler, and further, low density polyethylene, ethylene, and 3 to 8 carbon atoms. Of these, a blend of a copolymer with at least one α-olefin is preferred from the viewpoint of extrusion lamination and stretchability.

  The amount of the filler blended in the moisture permeable film 4 is 30 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. When the amount is less than 30 parts by mass, it is difficult to develop air permeability after stretching, and when it exceeds 300 parts by mass, there is a possibility of breaking at the time of stretching.

  The filler is blended with the thermoplastic resin in the form of fine powder. As the filler, both inorganic fillers and organic fillers can be used. Examples of inorganic fillers include carbonates such as calcium carbonate, magnesium carbonate and barium carbonate, sulfates such as barium sulfate, magnesium sulfate and calcium sulfate, phosphates such as magnesium phosphate and calcium phosphate, magnesium hydroxide, water Hydroxides such as aluminum oxide, oxides such as alumina, silica, magnesium oxide, calcium oxide, zinc oxide and titanium oxide, chlorides such as zinc chloride, iron chloride and sodium chloride, aluminum powder, zeoite, shirasu, clay, Examples include diatomaceous earth, talc, carbon black, and volcanic ash. Examples of organic fillers include cellulose-based powders such as wood powder and pulp powder, synthetic resin-based powders such as nylon powder, polycarbonate powder, polypropylene powder, and poly-4-methylpentene-1 powder, and starch. These may be used alone or in combination of two or more. Among the fillers described above, in the present invention, calcium carbonate is particularly preferably used from the viewpoint of the breathability, flexibility, appearance and the like of the final breathable packaging material 1. The average particle diameter of the filler is preferably 0.1 to 20 μm from the viewpoint of uniformity of the moisture permeable film 4, and more preferably 0.8 to 5.0 μm from the viewpoint of workability.

The draw ratio for obtaining the moisture-permeable film 4 in which micropores are formed is 1.02 or more. When the draw ratio is less than 1.02, micropores are not sufficiently formed, and it becomes difficult to obtain desired moisture permeability. In order to exhibit high air permeability at such a low draw ratio, the thermoplastic resin preferably contains 30% by mass or more of a resin having a density of 0.920 g / cm ³ or more.

  As described above, according to the breathable packaging material 1 of the present embodiment, the non-stretched nylon perforated film 2 is reinforced with the reinforcing material layer 3 having a ventilation portion, thereby ensuring breathability. As compared with conventional packaging materials in which paper and a reinforcing material layer are laminated, the breathable packaging material 1 having excellent mechanical strength such as tensile strength can be obtained. Moreover, as will be described later, the moisture permeability of the breathable packaging material 1 is the thickness of the reinforcing material layer 3 at the intersection position P, that is, the total thickness of the first fibers 11 and the second fibers 12 is 120 μm. It can adjust by setting suitably in the above range. Therefore, the moisture permeability required for the package 6 can be easily ensured.

  As described above, the mechanical strength of the breathable packaging material 1 is excellent, so that when the package is formed using the breathable packaging material 1, damage due to the functional article housed therein is not likely to occur. In addition to the oxygen agent and the desiccant, it can also be effectively used as a large packaging material for storing heavy functional articles such as activated carbon and charcoal. Further, since the surface layer of the package is the perforated film 2, paper dust is not generated as in the prior art, and it is hygienic. Furthermore, since the moisture-permeable film 4 which becomes a heat seal layer when forming a package uses a polyolefin-based resin as a thermoplastic resin, the melting point difference from the perforated film 2 which is a surface layer becomes large. Accordingly, the heat sealing temperature can be set high to shorten the heat sealing time, and the filling speed of the functional article can be increased accordingly, so that the productivity of the package can be improved.

  By using a split fiber nonwoven fabric as the reinforcing material layer 3, the strength balance in the longitudinal direction and the transverse direction is excellent, and the tensile strength and moisture permeability can be further improved.

  Furthermore, since the breathable packaging material 1 of this embodiment can be manufactured by joining the perforated film 2, the reinforcing material layer 3, and the moisture permeable film 4 at a stretch by a thermocompression bonding method, also from the viewpoint of manufacturing cost. It is advantageous.

  The breathable packaging material of the present invention can be suitably used for desiccant packaging, but also for packaging functional articles such as oxygen scavengers, moisturizers, fragrances, hygroscopic agents, deodorants, insect repellents, and dehumidifiers. It can be suitably used. The package for storing these functional articles may be in any form as long as the functional articles function. When the package is in the form of a bag, the breathable packaging material is used on a portion, one side, or the whole of the bag. A heat press method using a heat seal bar is generally used as a heat sealing method for a breathable packaging material for forming a package. Therefore, when the package is in the form of a bag, a general bag making and packaging machine that forms a bag from a sheet material can be used. Moreover, since the breathable packaging material of this invention is excellent in tensile strength as mentioned above, it can be utilized also as a large sized package and a sheet-like package.

  Next, typical examples of the present invention will be described together with comparative examples. Breathable packaging materials were produced by the methods shown in Examples 1 and 2 below, and the thickness of the reinforcing material layer, the tensile strength in the longitudinal and transverse directions, and the moisture permeability were measured for each. For the measurable material, the thickness of the warp (first fiber) and weft (second fiber) of the reinforcement layer was also measured. The reinforcing material layer and the thickness in the vertical and horizontal directions were measured by microscope observation. The tensile strength was measured according to JIS P 8113 (1998). The moisture permeability was measured according to JIS Z 0208 (cup method).

Example 1
As a perforated film, an unstretched nylon film having a thickness of 15 μm was prepared, and fine holes were formed by piercing a needle having a diameter of 0.3 mm at a vertical and horizontal interval of 3 mm. On one side, necessary prints such as product logos were applied by gravure printing. As the reinforcing material layer, the product number SS (T) (weight per unit area 20 g / m ² , intersection thickness 120 μm, vertical length of “Warif” (trade name, manufactured by Nippon Oil Plastic Co., Ltd.), which is a polyethylene non-woven fabric. Web thickness 45 μm, weft thickness 75 μm) was used. As the moisture permeable film, “Porum” (trade name, manufactured by Tokuyama Corporation), which is a stretched PE moisture permeable film containing an inorganic filler, was used, and the thickness was selected to be 35 μm. With the nylon film printed layer on the inside, corona treatment is applied to the side of the reinforcing material layer where the fibers are arranged in the lateral direction, and the moisture-permeable film is further fed out simultaneously so as to come into contact with the printed layer. The product was passed through a roll to produce a breathable packaging material. The lamination conditions were a heat roll temperature of 130 ° C., a linear pressure of 200 N / cm, and a feed rate of 20 m / min. The nylon film side is in contact with the heat roll. The corona treatment was performed at an output of 100 W / (m ² · min.).

(Example 2)
Part number HS (T) (weight per unit area: 36 g / m2, weight of intersection 140 μm, warp thickness, “Warif” (trade name, manufactured by Nippon Petroleum Co., Ltd.), a split fiber nonwoven fabric made of polyethylene, as a reinforcing material layer A breathable packaging material was prepared in the same manner as in Example 1 except that 55 μm and weft thickness of 85 μm were used.

(Example 3)
As a reinforcing material layer, the product number EX (T) (weight per unit weight 48 g / m ² , weight of intersection 200 μm, warp yarn, “Warif” (trade name, manufactured by Nippon Petroleum Co., Ltd.) which is a polyethylene split fiber nonwoven fabric A breathable packaging material was produced in the same manner as in Example 1 except that a thickness of 78 μm and a weft thickness of 122 μm were used.

Example 4
The same as in Example 1 except that “SOF” (product name, manufactured by Sekisui Film Co., Ltd.), which is a non-woven fabric made of polyethylene, was used as the reinforcing material layer, product number TS605 (weight per unit area 44 g / m ² , thickness 175 μm). Thus, a breathable packaging material was produced.

(Example 5)
Except for using as a reinforcing material layer part number R05090 (weight per unit area 23 g / m ² , intersection thickness 500 μm) of a net “Thermanet” (trade name, manufactured by Global Netting Solutions Co., Ltd.) which is a polyethylene vinyl acetate layer on both sides. A breathable packaging material was prepared in the same manner as in Example 1.

(Comparative Example 1)
The same as in Example 1 except that “SOF” (product name, manufactured by Sekisui Film Co., Ltd.), which is a non-woven fabric made of polyethylene, was used as the reinforcing material layer, product number TS405 (weight per unit area 31 g / m ² , thickness 90 μm). Thus, a breathable packaging material was produced.

(Comparative Example 2)
As a perforated film, a perforated film was produced in the same manner as in Example 1 using a biaxially stretched polyethylene terephthalate film having a thickness of 20 μm, and a breathable packaging material was produced. The split fiber nonwoven fabric was subjected to corona treatment and thermocompression bonded with polyethylene terephthalate by a thermal lamination method.

The physical property values are shown in Table 1. In FIG. 4, the relationship between the intersection thickness of the reinforcing material layer obtained in each Example and the comparative example 1 and moisture permeability is shown. It can be seen that in order to obtain the desired moisture permeability, it is necessary to set the intersection thickness of the reinforcing material layer accurately. In Example 1-5 in which the thickness of the reinforcing material layer is increased, the moisture permeability is higher than that of a packaging material conventionally used when quicklime is used as a desiccant (the moisture permeability is approximately 200 g / (m ² · 24 hr)). It can be seen that it has been realized.

In a packaging material used for a desiccant such as silica, clay, or calcium chloride, moisture permeability of several times that when quick lime is used as a desiccant is required. Unstretched nylon film is 460g / (m ² · 24hr) but moisture permeability is only about, ensuring 2500g / (m ² · 24hr) about the moisture permeability by the apertured film 2 formed micropores to it can. For this reason, if only the moisture permeability is taken into consideration, it is conceivable that the packaging material is constituted only by the perforated film, but since there is no heat seal layer, it cannot be used as a packaging material for a desiccant as it is. For this reason, it is conceivable to provide a heat-seal layer with a low melting point, such as polyethylene, and drill holes, but if the contents of the desiccant are very fine powder, the contents may leak from the holes. There is.

Therefore, in order to prevent the contents from leaking, the breathable packaging material of this embodiment uses a porous moisture-permeable film. Moisture permeability of typical porous moisture-permeable film ^{is, 9900g / (m 2 · 24hr} ) at a basis weight 35 g / m ^2, a 11200 / in basis weight ^{50g / m 2 (m 2 ·} 24hr). Since the moisture permeable waterproof film has a lower melting point than the nylon film, heat sealing is possible and the sealing strength is high. Moreover, it is excellent in hot tack property and the filling speed can be increased. However, since the porous moisture-permeable film has low tensile strength and tear strength, and similarly the porous nylon film has low strength, when using these members to prepare a desiccant packaging material, a reinforcing material is required. Therefore, in the breathable packaging material of this embodiment, the above-described breathable mesh is used as a reinforcing material (reinforcing material layer).

By changing the thickness of the reinforcing material layer, the present inventors form a gap where the perforated nylon film does not contact other members in the vicinity of the contact portion between the reinforcing material layer (second fiber) and the perforated nylon film. It was found that it is effective to maintain the high moisture permeability of the perforated nylon film as much as possible. By changing the thickness of the reinforcing material layer, the moisture permeability can be controlled in a wide range of 500 to 2000 g. This is a water vapor transmission rate that is much higher than the conventional level of about 200 g / (m ² · 24 hr). The inventor of the present application believes that such high moisture permeability can be obtained if the intersection thickness of the reinforcing material layer is 120 μm or more. This makes it possible to handle desiccants such as silica-based, clay-based, or calcium chloride, has mechanical strength and sufficient moisture permeability for the entire packaging material, and can prevent the occurrence of fuzz and the like. It becomes possible to provide a material and a package using the same. When the thickness of the reinforcing material layer becomes small, voids are not formed on the sides of the second fibers, and the moisture permeability becomes small and cannot be used for the desiccant.

  As is clear from Comparative Example 2, even if a perforated film is similarly produced using polyethylene terephthalate instead of a nylon film for the surface layer, the moisture permeability is small, and it is used as a packaging material for a silica-based desiccant or the like. Can not do it. From this, it was confirmed that it is important to use a material having sufficient moisture permeability for the surface layer. In Comparative Example 2, sufficient adhesive strength cannot be obtained, and it is difficult to use as a packaging material.

  FIG. 5 shows a cross-sectional view of the breathable packaging material prepared in Example 2. FIG. 4A is a cross-sectional photograph, and FIG. 2B is a sketch drawn based on the photograph of FIG. 1A, both representing the same contents. The first fibers (warp yarns) 11 and the second fibers (weft yarns) 12 intersect to form a three-dimensional network structure. In the vicinity of the intersection P between the weft yarn and the perforated film, the perforated film 2 swells upward so as to ride on the weft yarn 12, and a gap 8 extending along the weft yarn 12 is formed on the side of the weft yarn 12.

  The effects of the present invention will be further described with reference to FIGS. The arrangement pitch of the pores 7 of the perforated film 2 is larger than the arrangement pitch of the first fibers (warp yarns) 11 and the second fibers (weft yarns) 12. For this reason, the water vapor that has flowed from the pores 7 of the perforated film 2 advances in the space between the warp yarn 11 and the weft yarn 12 in a two-dimensional manner in the transverse direction (x direction and y direction). Invade the hole. Specifically, water vapor first enters the pores 7 of the perforated film 2 downward in the z direction (path a1), and then most of the water vapor that has entered thereafter travels in the y direction along the space between the weft threads 12 (path). a2). Further, the water vapor sequentially branches in the x direction as it advances in the y direction, advances in the space between the warp yarns 11 in the x direction (path a3), and finally enters the micropores of the moisture permeable film 4 downward in the z direction ( Route a4) is trapped by the internal desiccant.

  Therefore, in order to increase moisture permeability, a two-dimensional path in the in-plane direction of the reinforcing material layer 3 is ensured until water vapor enters the micropores of the moisture permeable film 4 from the pores 7 of the perforated film 2. It becomes important. In Examples 1 to 5, it is possible to ensure the thickness of the reinforcing material layer and thereby sufficiently ensure the height of the two-dimensional path. On the other hand, in the comparative example 1, the thickness of the reinforcing material layer is insufficient, and therefore the height of the two-dimensional path cannot be sufficiently secured. For this reason, the inflow resistance of water vapor increases and external water vapor cannot be taken in effectively.

  In particular, in order to obtain a high moisture permeability, it is effective to diffuse the water vapor over a wide range immediately after the water vapor enters the pores 7 of the perforated film 2. For this purpose, it is necessary to secure a sufficient cross-sectional area of the path a2. In general, it is easier to secure the height h1 and the width d (see FIG. 4) of the space 8 constituting the path a2, when the thickness (diameter) of the second fiber 12 is larger than that of the first fiber 11. It is considered more preferable. On the other hand, in order to obtain high moisture permeability, we considered increasing the number of holes in the perforated film and increasing the number of the perforated films, but the perforated film itself was greatly damaged, and the film was transported stably in the thermocompression bonding process. It was difficult to do and sometimes broke along the way. Therefore, there is a limit to controlling the moisture permeability by adjusting the holes of the perforated film, and it is effective to control the moisture permeability by changing the thickness of the reinforcing material layer as in the present invention. found.

It is typical sectional drawing of the air permeable packaging material by one Embodiment of this invention. Sectional drawing of the package produced using the air permeable packaging material shown in FIG. 1 is shown. It is a fragmentary perspective view of the reinforcing material layer of the air permeable packaging material shown in FIG. It is a graph which shows the relationship between the intersection thickness of a reinforcing material layer, and a water vapor transmission rate. 3 is a cross-sectional view of a breathable packaging material created in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Breathable packaging material 2 Perforated film 3 Reinforcing material layer 3a 1st fiber layer 3b 2nd fiber layer 4 Porous moisture permeable film 5 Functional article 6 Packaging 7 Pore 8 Void 11 First Fiber (warp)
12 Second fiber (weft)
h Intersection thickness P Intersection

Claims (8)

A perforated film made of nylon, a reinforcement layer having a network structure, and a porous moisture-permeable film are laminated in this order,
The reinforcing material layer faces the porous moisture-permeable film, faces a first fiber layer composed of a plurality of first fibers arranged in the same direction, and faces the perforated film. And a second fiber layer composed of a plurality of second fibers arranged in a direction different from the fibers and in the same direction as each other, and the second fiber layer is formed on the side of the second fibers. A breathable packaging material in which voids are formed along the fibers.   The breathable packaging material according to claim 1, wherein a thickness of the reinforcing material layer at an intersection of the first fiber and the second fiber is 120 µm or more.   The breathable packaging material according to claim 1 or 2, wherein printing is performed on a surface of the perforated film facing the reinforcing material layer.   The breathable packaging material according to any one of claims 1 to 3, wherein the porous moisture-permeable film is a microporous film made of a polyolefin resin.   The breathable packaging material according to any one of claims 1 to 4, wherein the reinforcing material layer is a split fiber nonwoven fabric made of a polyolefin resin.   The split fiber nonwoven fabric is a nonwoven fabric in which the first fibers of the first fiber layer are arranged in the vertical direction, and the second fibers of the second fiber layer are arranged in the horizontal direction, The breathable packaging material according to claim 5, wherein the second fiber layer is bonded to the perforated film by a thermocompression bonding method.   The breathable packaging material according to claim 6, wherein the second fibers are formed thicker than the first fibers.   A breathable packaging material according to any one of claims 1 to 7 is used for at least a part thereof, and the perforated film layer is disposed on the outside so that an oxygen scavenger, a desiccant, a heat generating agent, a hygroscopic agent, a deodorant, an insect repellent A package containing an agent, dehumidifier or fragrance.