JP6393571B2 - Breathable packaging material - Google Patents

Description

  The present invention relates to a breathable packaging material. In particular, the present invention relates to a breathable packaging material that satisfies standards such as the Food Sanitation Law and can be used for many purposes including food.

  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 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. Such packaging materials such as desiccants, oxygen scavengers, and freshness-keeping agents are required to have air permeability because of evaporation of components for oxygen removal, drying, or freshness preservation.

  A breathable packaging material formed by laminating a perforated film made of nylon, a reinforcing material layer having a network structure, and a microporous moisture-permeable film in this order by the present applicants is known ( For example, see Patent Document 1). This breathable packaging material has mechanical strength and sufficient moisture permeability, and does not cause inconvenience such as fluffing.

JP 2010-105312 A

  However, with the diversification of food packaging forms, it has higher functionality in line with the standards of the Food Sanitation Law such as oil resistance, water resistance, and acid resistance compared to conventional breathable packaging materials. There is a need for breathable packaging materials.

  The present invention has been made to solve the above problems. The present inventors have found that adhesion between layers can be further improved with respect to conventional packaging materials, and characteristics such as acid resistance can be imparted while maintaining conventional characteristics, and the present invention has been completed. It was. That is, the present invention, according to one embodiment, is a breathable packaging material, in which a porous polyethylene terephthalate layer, a porous polyethylene layer, a reinforcing material layer, and a microporous film layer are laminated in this order. The reinforcing material layer is arranged in the same direction as the first fiber layer composed of a plurality of first fibers arranged in the same direction and in the direction different from the first fibers. A second fibrous layer composed of a plurality of second fibers is a network structure that is laminated or woven.

  In the breathable packaging material, the porous polyethylene terephthalate layer, the porous polyethylene layer, the reinforcing material layer, and the microporous film layer have a temperature of 120 to 140 ° C. and a linear pressure of 200 to 260 N. It is preferably thermocompression-bonded at / cm.

  In the breathable packaging material, it is preferable that air communication in the direction parallel to the surface of the reinforcing material layer is prevented.

  In the breathable packaging material, the network structure is a non-woven fabric obtained by laminating a split fiber film obtained by splitting and stretching a longitudinally uniaxially stretched multilayer polyolefin film so that the stretching directions are orthogonal to each other. Preferably there is.

  In the breathable packaging material, after the network structure splits the longitudinally uniaxially stretched multilayer polyolefin film, the split fiber film obtained by widening, and the multilayer polyolefin film, after forming slits in the width direction, A nonwoven fabric obtained by laminating a net-like film obtained by uniaxial stretching in the transverse direction so that the stretching directions are orthogonal to each other is preferable.

  The breathable packaging material described in any of the foregoing preferably has a 4% acetic acid evaporation residue of 30 μg / ml or less based on the standard of the Food Sanitation Law.

  According to another aspect of the present invention, there is provided a method for producing a breathable packaging material, wherein a porous polyethylene terephthalate layer, a porous polyethylene layer, a reinforcing material layer, and a microporous film layer are laminated in this order. And the step of thermocompression bonding the laminate obtained by the above step at a temperature of 120 to 140 ° C. and a linear pressure of 200 to 260 N / cm, and the reinforcing material layers are arranged in the same direction as each other A first fiber layer made of a plurality of first fibers, and a second fiber layer made of a plurality of second fibers arranged in the same direction as the first fibers, A network structure that is laminated or woven.

  According to another embodiment of the present invention, there is provided a package, wherein the breathable packaging material according to any one of the foregoing is used at least in part, with the perforated polyethylene terephthalate layer on the outside, an oxygen scavenger, It contains a desiccant, freshness-retaining agent, exothermic agent, hygroscopic agent, deodorant, insect repellent, dehumidifying agent or fragrance.

  According to another aspect of the present invention, there is provided a method for manufacturing a package, wherein the breathable packaging material according to any one of the foregoing is used at least in part, and both ends of the microporous film layer are in contact with each other. The step of making the air-permeable packaging material into a bag shape with the microporous film layer inside, and the bag-like air-permeable packaging material with an oxygen scavenger, a desiccant, a freshness retaining agent, an exothermic agent, and a hygroscopic agent And a step of housing a deodorant, an insect repellent, a dehumidifying agent or a fragrance, and a step of heat-sealing the peripheral portion of the bag-shaped breathable packaging material by a hot press method.

  According to the present invention, the conventional mechanical strength, air permeability, moisture permeability, etc. are sufficiently retained, and the oil permeability, water resistance, and acid resistance are excellent, and the air permeability conforming to the standards of the Food Sanitation Law. A packaging material can be obtained. In addition, the breathable packaging material of the present invention can be used even in a humid environment, and is particularly suitable as a packaging material for an oxygen scavenger and a freshness-keeping agent. Furthermore, the breathable packaging material according to the present invention is excellent in smoothness, is suitable for molding by the heat seal method, and is rich in applicability to various forms.

1 is a conceptual cross-sectional view of a breathable packaging material according to a first embodiment of the present invention. It is a fragmentary perspective view of a split fiber film (longitudinal web) which is an example of a member which constitutes a network structure. It is the fragmentary perspective view which performed the split fiber process to the original fabric film used for manufacture of the split fiber film shown in FIG. It is a fragmentary perspective view of the net-like film (horizontal web) which is an example of the member which comprises a net-like structure. It is the fragmentary perspective view which gave the slit process to the original fabric film used for manufacture of the reticulated film shown in FIG. It is a conceptual diagram which shows the example of the reinforcing material layer which comprises the air permeable packaging material shown in FIG. It is a conceptual sectional view of the package concerning a 2nd embodiment of the present invention. 2 is a cross-sectional photograph of a breathable packaging material according to Example 1. 4 is a cross-sectional photograph of a breathable packaging material according to Comparative Example 1.

[First embodiment: Breathable packaging material]
The present invention relates to a breathable packaging material according to the first embodiment. FIG. 1 is a conceptual cross-sectional view of a breathable packaging material 1 according to the first embodiment of the present invention. The breathable packaging material is formed by laminating a porous polyethylene terephthalate layer 11, a porous polyethylene layer 12, a reinforcing material layer 10 having a network structure, and a microporous film layer 13 in this order. Below, each layer which comprises the air permeable packaging material 1 is demonstrated in detail.

(1) Perforated polyethylene terephthalate layer The perforated polyethylene terephthalate layer 11 constitutes one outermost surface layer in the breathable packaging material 1 and normally functions as a layer in contact with food. For the perforated polyethylene terephthalate layer 11, a general polyethylene terephthalate film material is used. The thickness of the perforated polyethylene terephthalate layer 11 can be appropriately determined by those skilled in the art according to the purpose and application of the breathable packaging material 1. For example, the thickness is about 5 to 50 μm, and typically 7 to 30 μm, but is not limited thereto. Moreover, the porous polyethylene terephthalate layer 11 has pores 50 formed at regular intervals as shown in FIG. The pores 50 are typically provided so as to penetrate all of the perforated polyethylene terephthalate layer 11 and an optional printed layer (not shown) described later, and the perforated polyethylene layer 12. This is to ensure air permeability. As the size of the pore 50, for example, the pore diameter is about 0.05 to 0.5 mm, and typically 0.1 to 0.4 mm, but is not limited thereto. The density of the pores 50 is, for example, 2 to 10 mm, and typically 2.5 to 5 mm, but is not limited thereto.

  Further, the porous polyethylene terephthalate layer 11 may be colored although it depends on the presence or absence of printing described later. The perforated polyethylene terephthalate layer 11 may be a commercially available polyethylene terephthalate film, but can be appropriately produced by a generally known production method. Furthermore, if necessary, a polyethylene terephthalate layer having a surface treatment that imparts a desired function on the surface that is the outermost surface can be used.

  When the porous polyethylene terephthalate layer 11 forms a package using the breathable packaging material 1 according to the present embodiment, the porous polyethylene terephthalate layer 11 usually does not contact the inclusion and constitutes the outermost layer. Since the polyethylene terephthalate layer 11 has many uses in food packaging applications, there are advantages in that the resin has been widely used and the reliability in terms of quality is high.

  Printing can be performed on the back surface of the perforated polyethylene terephthalate layer 11, that is, the surface in contact with the perforated polyethylene layer 12. The perforated polyethylene terephthalate layer 11 can be printed clearly, and print information can be clearly seen from the surface side. Since printing is performed on the back surface of the perforated polyethylene terephthalate layer 11, the printing portion is not exposed on the surface of the package, and even if the package is stored together with food, the printing ink does not come into contact 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.

(2) Perforated polyethylene layer The perforated polyethylene layer 12 functions as an adhesive between the perforated polyethylene terephthalate layer 11 and the reinforcing material layer 10, and improves the adhesion between the layers. As the porous polyethylene layer 12, for example, general-purpose low density polyethylene can be used. The thickness of the perforated polyethylene layer 12 can be appropriately determined by those skilled in the art according to the purpose and use of the breathable packaging material 1. For example, the thickness is about 5 to 50 μm, and typically 7 to 30 μm, but is not limited thereto. The perforated polyethylene layer 12 is formed with pores 50 penetrating from the perforated polyethylene terephthalate layer 11 through a printing layer that is optionally provided.

(3) Microporous film layer The microporous film layer 13 constitutes the outermost surface opposite to the perforated polyethylene terephthalate layer 11, and when the breathable packaging material 1 is used as a package, Functions as a contact surface. The microporous film layer 13 is a film made of a polyolefin-based thermoplastic resin, and forms a micropore in the resin composition by stretching a resin composition made of a polyolefin-based resin containing a filler. It is given air permeability. The thickness of the microporous film layer 13 can be appropriately determined by those skilled in the art according to the purpose and application of the breathable packaging material 1. For example, it is about 5 to 70 μm, and typically 10 to 50 μm, but is not limited thereto. Moreover, in the packaging material aiming at shape | molding as a package body mentioned later especially, it is preferable that melting | fusing point of the microporous film layer 13 is 120 degrees C or less. This is because it is advantageous in heat-sealing bags. Such a low melting point can be realized by a preferable specific resin composition described later.

  Specifically, examples of the thermoplastic resin used for the microporous film layer 13 include α-olefin homopolymers such as low density polyethylene, high density polyethylene, polypropylene, and polybutene, and at least one of ethylene and 3 to 18 carbon atoms. Copolymers of α-olefins, copolymers of propylene and ethylene and / or butene-1, organic carboxylic acids having an ethylenically unsaturated bond, such as ethylene and vinyl acetate and / or acrylic esters and methacrylic esters Examples include copolymers with acid derivatives. 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 to be blended in the microporous film layer 13 is preferably 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 during 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, zeolite, 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 size of the filler is preferably 0.1 to 20 μm from the viewpoint of uniformity of the microporous film layer 13, and more preferably 0.8 to 5.0 μm from the viewpoint of workability.

The draw ratio for making the thermoplastic resin containing the filler into the microporous film layer 13 is preferably 1.02 or more. If the draw ratio is less than 1.02, micropores are not sufficiently formed, and it becomes difficult to obtain a desired air 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.

(4) Reinforcing Material Layer The reinforcing material layer 10 is located between the perforated polyethylene layer 12 and the microporous film layer 13 and imparts mechanical strength to the breathable packaging material 1 according to this embodiment. Ensure the necessary breathability. The reinforcing material layer 10 includes a first fiber layer composed of a plurality of first fibers arranged in the same direction and a plurality of second fibers arranged in a direction different from the first fibers and in the same direction. The second fiber layer made of the above fibers is a network structure that is laminated or woven. Examples of such a network structure include various embodiments and are not particularly limited, but those having a certain strength and air permeability derived from the network structure are preferable.

  The network structure is preferably formed by laminating a second fiber layer in which the second fibers are arranged in the longitudinal direction and a first fiber layer in which the first fibers are arranged in the transverse direction. There is no particular limitation on which fiber layer of the first fiber layer and the second fiber layer is in contact with the porous polyethylene layer 12. 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, and the like, and is also referred to as a length direction. “Lateral direction” means a direction perpendicular to the longitudinal direction, that is, the width direction of a nonwoven fabric, web, laminate, or the like. Hereinafter, a specific structure and manufacturing method of the network structure functioning as the reinforcing material layer 10 will be described.

[First network structure: split fiber nonwoven fabric]
In one embodiment, the network structure is a split fiber nonwoven fabric obtained by splitting a longitudinal fiber monoaxially stretched multilayer polyolefin film and then splitting the resulting split fiber film so that the stretch direction is substantially orthogonal. It is. That is, in the first embodiment, the first fiber layer and the second fiber layer are both split fiber films, and the arrangement direction of the fibers is substantially orthogonal.

  FIG. 2 shows a split fiber film (longitudinal web) in which fibers are arranged in the longitudinal direction, which is an example of a second fiber layer according to the present embodiment. As shown in FIG. 2A, the split fiber film 102 has a plurality of trunk fibers 102c extending in parallel with each other, and intersecting with the trunk fibers 102c, and adjacent trunk fibers 102c. It is comprised with the branch fiber 102d which connects. The branch fibers 102d are thinner than the trunk fibers 102c, and the mechanical strength of the split fiber film 102 is mainly provided by the trunk fibers 102c. The split fiber film 102 has a high tensile strength in the stretching direction. Then, as shown in FIG. 2B, the split fiber film 102 is formed by sequentially laminating a second thermoplastic resin layer 102b, a first thermoplastic resin layer 102a, and a second thermoplastic resin layer 102b. It has a three-layer structure.

  In the split fiber film 102, the thickness of the second thermoplastic resin layer 102b is 50% or less, desirably 40% or less, of the total thickness of the second fiber layer. In order to satisfy various physical properties such as adhesive strength at the time of thermal welding between the first fiber layer and the second fiber layer, the thickness of the second thermoplastic resin layer 102b may be 5 μm or more, preferably Is selected from the range of 10 to 50 μm. In addition, the thickness here is the thickness before extending | stretching.

  The first thermoplastic resin layer 102a and the second thermoplastic resin layer 102b are resin layers mainly composed of a thermoplastic resin. Examples of the thermoplastic resin include polyolefins such as polyethylene and polypropylene, which have good splitting properties, and copolymers thereof. Further, the difference in melting point between the first thermoplastic resin and the second thermoplastic resin is required to be 5 ° C. or more, and preferably 10 to 50 ° C. for manufacturing reasons.

  The illustrated split fiber film 102 has a three-layer structure, but may be a single layer or two layers. Alternatively, it may be provided with more layers, for example, a four-layer, five-layer, or six-layer structure.

  Examples of the method for producing the split fiber film 102 include the following methods. First, a resin constituting each layer is kneaded, and then an original film having a three-layer structure is manufactured by extrusion molding such as a multilayer inflation method or a multilayer T-die method. Next, as shown in FIG. 3, the raw film 200 is stretched in the longitudinal direction (L direction in the figure). The draw ratio (orientation ratio) is preferably 1.1 to 15 times, more preferably 3 to 10 times. If the draw ratio is less than 1.1 times, the mechanical strength may not be sufficient. On the other hand, when the draw ratio exceeds 15 times, it is difficult to stretch by a usual method, and there may be a problem that an expensive apparatus is required. Stretching is preferably performed in multiple stages in order to prevent stretching unevenness. Next, the stretched film is split in a vertical direction (L direction shown in FIG. 3) in a zigzag manner using a splitter (split treatment) to form a large number of parallel slits 200a. Furthermore, it widens in the direction orthogonal to this. Thereby, the split fiber film 102 as shown to Fig.2 (a) is obtained. The split fiber film 102 thus manufactured has a high tensile strength in the stretching direction.

  Next, two pieces of the obtained split fiber film 102 are overlapped so that the trunk fibers are substantially orthogonal to each other, and this is heated and welded. At this time, one of the two split fiber films corresponding to the second fiber layer can be continuously supplied in-line in the machine direction. The other split fiber film corresponding to the first fiber layer is manufactured as described above, and the wound split fiber film is cut into the same length as the width of the split fiber film supplied in-line. Then, the tiles are intermittently supplied and overlapped. When heat-welding, the two split fiber films overlapped are supplied between a pair of opposed heating cylinders and fixed so as not to shrink in the width direction, and the stretching effect of the surface layer is lost. In order to prevent this, thermal welding is performed at a temperature not higher than the melting point of the thermoplastic resin constituting the inner layer and not lower than the melting point of the thermoplastic resin constituting the surface layer. Thereby, a network structure can be obtained. In addition, it can replace with the heat welding in the manufacturing method of a network structure, and can also integrate using other arbitrary adhesion means, such as an adhesive material.

  The reinforcing material layer 10 made of the split fiber nonwoven fabric configured as described above has a mesh structure and has a certain opening ratio, and therefore has air permeability. Examples of typical commercial products of such split fiber nonwoven fabric include, but are not limited to, JX Nippon Mining & Energy Co., Ltd., Warif (registered trademark) S24L, SS28L and the like.

[Second network structure: network nonwoven fabric]
In another embodiment, the network structure includes a split fiber film obtained by splitting a longitudinally uniaxially stretched multilayer polyolefin film and then widening the slit, and a slit is formed in the width direction in the multilayer polyolefin film. A reticulated nonwoven fabric obtained by laminating a reticulated film obtained by uniaxial stretching in a direction so that the stretching directions are substantially orthogonal. That is, in the second embodiment, the first fiber layer is a split fiber film, and the second fiber layer is a mesh film. The first fiber layer and the second fiber layer are terms used for distinguishing between the two layers constituting the network structure, and are distinguished in the stacking order and relative relationship with other layers. It is not something.

  The shape, structure, and manufacturing method of the split fiber film constituting the first fiber layer are as described above.

  FIG. 4 shows a reticulated film (transverse web) in which fibers are arranged in the transverse direction, which is an example of the second fiber layer according to the present embodiment. As shown in FIG. 4A, the net-like film 103 is formed in a mesh shape having a substantially rhombic shape. And as shown in FIG.4 (b), the net-like film 103 laminated | stacked the 2nd thermoplastic resin layer 103b, the 1st thermoplastic resin layer 103a, and the 2nd thermoplastic resin layer 103b in order. It has a three-layer structure.

  The relationship between the thickness of the entire mesh film 103 and the thickness of the second thermoplastic resin layer 103b is the same as that described for the split fiber film 102 described above, and the resin material constituting the mesh film 103 is also described above. Substantially the same material as the split fiber film 102 can be used, and detailed description thereof is omitted.

  The method for producing the net-like film 103 is to first produce a three-layer original film, and then, as shown in FIG. 5, slits are staggered in the lateral direction (T direction shown in FIG. 5) with respect to the original film 300. Processing is performed to form a large number of parallel slits 300a. Thereafter, the raw film 300 is stretched in the lateral direction (T direction shown in FIG. 5). In this way, after forming slits in the original fabric film 300 in advance, the slit films 103 are stretched in the lateral direction to obtain a net-like film 103 in which rhombic meshes are formed. The slit 300a in the horizontal direction passes and conveys the raw film between a rotating roller having a linear protrusion formed in the axial direction on the outer peripheral surface of the cylinder and a rotating roller having a flat outer peripheral surface opposite to the rotating roller. Can be formed.

  Finally, the split fiber film 102 and the net-like film 103 are overlapped so that the stretching directions are substantially orthogonal, and these are heated and welded to obtain a net-like structure made of a net-like non-woven fabric. In this case, the mode of heat welding or adhesion may be the same as in the first embodiment.

  The reticulated film is not limited to the one having the rhombic reticulated structure shown in the figure. It is generally stretched in the transverse direction, and when it is overlapped with the split fiber film in the machine direction, it is only necessary that the stretch direction is substantially orthogonal. For example, similar to the split fiber film shown in FIG. A pattern composed of a plurality of extended trunk fibers and branch fibers that extend across the trunk fibers and connect adjacent trunk fibers, and rotated by ± 90 ° with respect to the split fiber film when viewed in plan Alternatively, it may have a similar pattern.

  When laminating a network structure composed of a network nonwoven fabric with the porous polyethylene terephthalate layer 11, the porous polyethylene layer 12 and the microporous film layer 13 shown in FIG. It may be laminated so that the side contacts the porous polyethylene layer 12, or may be laminated so that the mesh film 103 side contacts the porous polyethylene layer 12.

  The reinforcing material layer 10 itself made of a net-like nonwoven fabric configured as described above has a mesh structure and has a certain aperture ratio, and therefore has air permeability. As an example of a typical commercial item of such a network nonwoven fabric, JX Nippon Mining & Energy Co., Ltd., CLAF (registered trademark) SS (T) EL, 3S (T), S (F) EL can be mentioned. However, it is not limited to these.

[Third network structure: non-woven fabric / woven fabric composed of longitudinally uniaxially stretched multilayer polyolefin tape]
In yet another embodiment, the network structure is a nonwoven fabric or a woven fabric formed by weaving longitudinally uniaxially stretched multilayer polyolefin tapes. That is, both the first fiber layer and the second fiber layer are composed of a plurality of longitudinally uniaxially stretched multilayer polyolefin tape groups. In the case of a nonwoven fabric, a plurality of longitudinally uniaxially stretched multilayer polyolefin tape groups are laminated and welded or bonded so that the stretching directions are substantially orthogonal. In the case of woven fabric, a plurality of longitudinally uniaxially stretched multilayer polyolefin tape groups are warp yarns, and a plurality of longitudinally uniaxially stretched multilayer polyolefin tape groups are weft yarns. The direction is in the transverse direction) and is woven in any weave and welded or bonded.

  As in the case of the split fiber film described in the first embodiment, the longitudinally uniaxially stretched multilayer polyolefin tape is manufactured by producing a three-layer raw film by extrusion molding such as a multilayer inflation method or a multilayer T-die method. 1.1 to 15 times, preferably 3 to 10 times, and then uniaxially stretched, and then cut along the stretching direction, for example, with a width of 2 mm to 7 mm. Alternatively, similarly, a three-layer original film is manufactured, cut in the same direction along the machine direction, and then uniaxially stretched 1.1 to 15 times, preferably 3 to 10 times in the machine direction. Can be manufactured.

  An example of a network structure composed of a nonwoven fabric is shown in FIG. In FIG. 6, the network structure 40 includes a plurality of uniaxially stretched multilayer tapes corresponding to warps arranged in parallel as a first fiber layer 402 at a certain interval, and the longitudinal direction of the uniaxially stretched multilayer tape is substantially perpendicular to the mesh structure 40. As described above, another uniaxially stretched multilayer tape corresponding to the weft is laminated as the second fiber layer 403. And the network structure is obtained by heat-welding the contact surface of a warp and a weft. In this case, the mode of heat welding or adhesion is the same as that of the above-mentioned embodiment. The woven fabric can be produced in the same manner except that a plurality of uniaxially stretched multilayer tapes are woven instead of being laminated.

  As an example of such a commercial product of nonwoven fabric, Sof (trade names) HN55 and HN66 manufactured by Sekisui Film Co., Ltd. can be used. As an example of a commercially available woven fabric, Meltac (trade name) manufactured by Ebara Industries Co., Ltd. can be used.

[Fourth network structure: various laminates]
In addition, the reinforcing material layer 10 is formed by laminating the above-mentioned split fiber film (longitudinal web) or net-like film (transverse web) and the longitudinal uniaxially stretched multilayer polyolefin tape so that the stretching direction is substantially orthogonal or crossed. It is also possible to use a laminated body or a woven fabric or a nonwoven fabric in which filaments spun from a thermoplastic resin and stretched are combined so that the stretching directions are substantially orthogonal. In short, it is only necessary that the plurality of network layers are integrated so that the extending directions are substantially orthogonal or crossed and have air permeability.

[Fifth network structure: Net object]
As still another example of the reinforcing material layer, a net-like material made of polyethylene or polypropylene can be used. Examples of the net-like material include Kurenet (trade name) manufactured by Kurabo Industries Co., Ltd., Conwed Net manufactured by Conwed, and Thermanet (trade name).

[Method for producing breathable packaging material]
Next, the breathable packaging material according to the present embodiment will be described from the viewpoint of the manufacturing method. As a method for producing a breathable packaging material, first, a polyethylene terephthalate film is printed on the back surface as necessary, and then a polyethylene layer is formed on the back surface by an extrusion coating method or the like. By subjecting this polyethylene terephthalate film having a polyethylene layer formed on the back surface to a hole opening treatment, a laminate of the porous polyethylene terephthalate layer 11 and the porous polyethylene layer 12 is obtained. Finally, the laminate, the reinforcing material layer 10, and the microporous film layer 13 are joined by a thermocompression bonding method. Bonding of these layers can be performed at a stretch by a thermocompression bonding method after each layer is individually manufactured, and the breathable packaging material 1 according to the present invention can be obtained by such steps. In this case, the thermocompression bonding conditions are, for example, 120 to 140 ° C., preferably 125 to 140 ° C., for example, a linear pressure of 200 to 260 N / cm, preferably a linear pressure of 210 to 260 N / cm. It can be a condition. In particular, the high pressure bonding condition with a linear pressure of 210 to 260 N / cm is more advantageous because water resistance, acid resistance, and heat resistance can be greatly improved. Although the specific method of thermocompression bonding can be implemented by a steam heating roll or a dielectric heating roll, it is not limited to these.

  In the breathable packaging material 1 obtained by the above production method, the reinforcing material layer 10 is at least partially embedded in the porous polyethylene layer 12 with which the reinforcing material layer 10 comes into contact, preferably partially embedded in the microporous film layer 13 as well. doing. When the cross-section of the breathable packaging material 1 after lamination and thermocompression bonding is observed by the method described later, the portion buried is a portion corresponding to the thickness of the porous polyethylene layer 12 before thermocompression bonding and / or microporous. This can be confirmed by the penetration of the reinforcing material layer 10 into the portion corresponding to the thickness of the conductive film layer 13. In some cases, the reinforcing material layer 10 bites in, so that the porous polyethylene layer 12 and / or the microporous film layer 13 loses flatness, and it can be confirmed that there are places where they are pushed up and rise.

  The porous polyethylene layer 12 and the microporous film layer 13 are in contact with each other and welded in at least a part of the opening of the reinforcing material layer 10 of the network structure. Similarly, when the cross section of the breathable packaging material 1 after lamination and thermocompression bonding is observed, the microporous structure is formed in the opening of the reinforcing material layer 10, that is, in the portion where neither the first fiber nor the second fiber exists. It can confirm by the location which the porous film layer 13 and the said porous polyethylene layer 12 contact is recognized.

  The structural features of the reinforcing material layer 10, the microporous film layer 13 in contact with the reinforcing material layer 10, and the perforated polyethylene layer 12 are such that air communication in the reinforcing material layer 10 is preferably performed in a direction parallel to the surface. To prevent. Referring to FIG. 1, the direction parallel to the surface of the reinforcing material layer 10, that is, the direction along the surface perpendicular to the direction in which the pores 50 are provided corresponds to the left-right direction of the paper surface. There is no air communication to. In the breathable packaging material 1, due to the presence of the pores 50 penetrating the perforated polyethylene terephthalate layer 11 and the perforated polyethylene layer 12, the reinforcing material layer 10 from the pore inlet on the perforated polyethylene terephthalate layer 11 side, A gas can enter the microporous film layer 13. That is, the gas can move in a direction substantially perpendicular to the surface of the breathable packaging material 1. In addition, when moisture is present in the laminated breathable packaging material 1, gas such as moisture and air is partly in a locally communicating space that can be formed by the reinforcing material layer 10 that is a member having irregularities. It is possible to move. However, as a whole, due to the close contact between the porous polyethylene layer 12, the reinforcing material layer 10, and the microporous film layer 13, and due to partial contact between the porous polyethylene layer 12 and the microporous film layer 13, Air communication in the direction parallel to the direction is blocked. Therefore, the pores 50 are filled with air, and the presence of this air prevents moisture from entering from the pore inlet on the porous polyethylene terephthalate layer 11 side. Therefore, in the breathable packaging material 1 according to the present invention, moisture does not enter the inside through the pores.

  And this breathable packaging material 1 is a form of the film which has the film thickness of about 150-250 micrometers normally, Preferably, about 100-200 micrometers, and has a flexibility. The breathable packaging material 1 according to the present embodiment has the above-described layer structure, so that it is a 4% acetic acid elution residue in the standard of food, additives, etc. (S34 Ministry of Health and Welfare Notification No. 370) based on the Food Sanitation Law. Conform to the test. Specifically, the breathable packaging material 1 according to this embodiment satisfies the evaporation residue “30 μg / ml or less” defined by the above-mentioned standard. The amount of evaporation residue of the breathable packaging material 1 according to the present embodiment is more preferably 20 μg / ml or less, and still more preferably 15 μg / ml or less. By conforming to this standard, it can be used for packaging materials such as a desiccant, a freshness-preserving agent, and an oxygen scavenger that are impossible in the prior art. Further, as described above, the breathable packaging material according to the present embodiment preferably prevents moisture from entering the packaging material itself by preventing air from communicating in a direction parallel to the surface of the reinforcing material layer. It is suitable for the 4% acetic acid elution residue test by suppressing, ie, increasing water resistance. If the water resistance is inferior, the oxidation of the contents to be packaged rapidly proceeds, for example, there is a problem that iron powder as an oxygen scavenger does not last long, but according to the breathable packaging material according to this embodiment Can overcome this problem. In addition, for example, when the content is iron powder, if the water resistance is low, the water that has entered from the pores has a problem that the black color of the iron powder is noticeable and the appearance is deteriorated. Can be overcome. Furthermore, the breathable packaging material according to the present embodiment similarly suppresses the infiltration of oil, that is, has improved oil resistance as compared with the prior art, and the oil enters and closes the holes of the perforated film. It is possible to prevent the air permeability of the material from being impaired. The air permeability required for the packaging material varies depending on the inclusion, and the desired number of pores of the porous polyethylene terephthalate film 11 and the porous polyethylene film 12 and the microporous film layer 13 can be adjusted by adjusting the air permeability. Can be air permeability

  Moreover, by providing the reinforcing material layer 10 as described above, the breathable packaging material 1 having excellent mechanical strength such as tensile strength similar to that of the prior art can be obtained, and a desired air permeability can be provided. Furthermore, by using the network structure described in the above embodiment as the reinforcing material layer, the strength balance in the vertical direction and the horizontal direction is excellent, and the tensile strength and air permeability can be further improved. Furthermore, the breathable packaging material 1 of the present embodiment is a laminate of a porous polyethylene terephthalate layer 11 and a porous polyethylene layer 12, a reinforcing material layer 10, and a microporous film layer 13 all at once by a thermocompression bonding method. Since it can manufacture by joining, it is advantageous also from the surface of manufacturing cost.

[Second Embodiment: Package]
The present invention, according to the second embodiment, is a package, which uses at least part of the breathable packaging material 1 according to the first embodiment, with the perforated polyethylene terephthalate layer on the outside, and an oxygen scavenger, dried It contains an agent, a freshness-keeping agent, an exothermic agent, a hygroscopic agent, a deodorizing agent, an insect repellent, a dehumidifying agent or a fragrance.

  FIG. 7 shows a conceptual cross-sectional view of the package according to the present embodiment. The packaging body 6 according to the second embodiment is formed by forming the breathable packaging material 1 according to the first embodiment into a bag shape so that the microporous film layer 13 is on the inside, and storing the functional article 5 therein. Become. In FIG. 7, the illustration of pores penetrating the perforated polyethylene terephthalate layer 11 and the perforated polyethylene layer 12 is omitted. When making the package 6 from the breathable packaging material 1, the microporous film layer 13 is used as a heat seal layer. Specifically, the breathable packaging material 1 is folded into a bag shape with the microporous film layer 13 inside so that both ends of the microporous film layer 13 face each other, and the functional article 5 is wrapped, and the peripheral portion is Heat seal by hot press method. Thereby, it seals so that the functional article 5 may not be discharge | released outside the package. Specific functional articles 5 include, but are not limited to, silica-based, clay-based or calcium chloride, iron powder, magnesium oxide, zeolite, and silica-ethanol.

  In the package 6 according to the present embodiment, for example, the functional article 5 can be used particularly preferably in order to enclose an oxygen scavenger and a freshness-keeping agent. The characteristics of the layer structure described as the characteristics of the breathable packaging material 1, in particular, the air communication in the direction parallel to the surface of the reinforcing material layer 10 is prevented, so that it can be used even in the presence of moisture. This is because even if water is present near the pores of the porous polyethylene terephthalate layer 11 that is the front side surface of the body 6, the movement of water from the pores to the inside is prevented.

  Due to the excellent mechanical strength of the breathable packaging material 1, when the packaging body 6 is formed using the breathable packaging material 1, the functional article 5 housed therein is less likely to be damaged, and the oxygen scavenger In addition to the desiccant and the desiccant, it can be effectively used as a large packaging material for storing the functional article 5 having a large weight such as activated carbon or charcoal. Moreover, since the surface layer of the package 6 becomes the porous polyethylene terephthalate layer 11, paper dust is not generated and it is hygienic. Furthermore, since the microporous film layer 13 which becomes a heat seal layer when forming the package 6 uses a polyolefin-based resin as a thermoplastic resin, the melting point difference from the perforated polyethylene terephthalate layer 11 which is a surface layer is large. Become. Accordingly, the heat sealing temperature can be set high to shorten the heat sealing time, and the filling speed of the functional article 5 can be increased accordingly, so that the productivity of the package 6 can be improved.

  The breathable packaging material of the present invention can be suitably used for packaging oxygen scavengers, desiccants, and freshness-retaining agents, but has functionalities such as moisturizers, fragrances, moisture absorbents, deodorants, insect repellents, and dehumidifiers. It can also be suitably used for packaging the article 5. The packaging body for storing these functional articles 5 may be in any form as long as the functional articles 5 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.

  Below, the typical Example of this invention is demonstrated with a comparative example. The following examples are intended to illustrate the present invention and are not intended to limit the present invention.

(Example)
A breathable packaging material according to the first embodiment of the present invention was produced. After applying necessary printing such as a product logo by gravure printing on one side of a polyethylene terephthalate film with a layer thickness of 12μm, extrusion coating is applied to the printed surface side so that the layer thickness is 15μm, and the vertical and horizontal intervals are Fine pores were formed by piercing a needle having a diameter of 0.3 mm at 3 mm. Each layer thus obtained is hereinafter also referred to as perforated PET and perforated PE. As the reinforcing material layer, “CLAF” (made by JX Nippon Mining & Energy Co., Ltd., trade name, registered trademark), which is a reticulated nonwoven fabric made of polyethylene, has a product number SS (T) EL (weight per unit area 20 g / m ² , A thickness of 110 μm, a vertical web thickness of 40 μm, and a horizontal web thickness of 70 μm) were used. As the microporous film layer, “Porum” (trade name, manufactured by Tokuyama Corporation), which is a stretched PE microporous film containing an inorganic filler, was used, and the thickness was selected to be 35 μm. Hereinafter, the microporous film is also referred to as MPF.

Make the porous polyethylene terephthalate layer and porous polyethylene layer in contact with the porous polyethylene layer while corona treatment is applied to the surface of the reinforcing material layer that contacts the porous polyethylene layer. Further, a microporous film was simultaneously fed out, and three layers were simultaneously passed through a hot roll to produce a breathable packaging material. The lamination conditions were a heat roll temperature of 130 ° C., a linear pressure of 260 N / cm, and a feed rate of 20 m / min. It was the porous polyethylene terephthalate layer side that contacted the hot roll. The corona treatment was performed at an output of 100 W / (m ² · min.).

(Comparative Example 1)
In place of the porous polyethylene terephthalate layer and porous polyethylene layer of the example, an unstretched nylon film with a thickness of 15 μm was prepared, and fine holes were formed by piercing needles with a diameter of 0.3 mm at a vertical and horizontal interval of 3 mm. (Perforated nylon, normal number of holes). Similarly, a non-stretched nylon film having a thickness of 15 μm was prepared, and pores were formed by piercing needles having a diameter of 0.3 mm at a longitudinal and lateral interval of 6 mm (perforated nylon, reduced number of pores). Moreover, the same reticulated nonwoven fabric CLAF as an Example was used as a reinforcing material layer, and the packaging material of the comparative example 1 was obtained like the Example. The configuration of Comparative Example 1 is the same as the configuration of Example 1 of Japanese Patent No. 5070560 by the applicants.

(Comparative Example 2)
A packaging material of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that cellophane having a thickness of 210 μm (PT-PL # 300 manufactured by Phutamura Chemical Co., Ltd.) was used instead of the unstretched nylon film of Comparative Example 1.

[Water and oil resistance evaluation test]
About the packaging material of an Example, the comparative example 1, and the comparative example 2, water resistance and oil resistance were evaluated. For water resistance and oil resistance, conduct a mounting test under the conditions in which the above packaging material is actually used, visually check whether moisture and oil have entered the packaging material, and if no intrusion is observed, The case where intrusion was recognized was set as x.

  Subsequently, acid resistance was evaluated about these packaging materials. The evaluation of acid resistance was based on standards for food hygiene law, food, additives, etc. (S34 Ministry of Health and Welfare Notification No. 370). Specifically, 4% acetic acid, which is a test method for equipment or containers and packaging made of synthetic resin mainly composed of polyethylene and polypropylene, used in contact with “foods other than fat and fatty foods and foods other than alcoholic beverages” is used. An elution test (measurement of evaporation residue) was performed on a test solution prepared using the leaching solution.

As a method of operation, the side opposite to the microporous film layer of the packaging material test body is fixed with a jig, and 200% to 300 ml of 4% acetic acid is introduced from above, and the solution leached at 60 ° C. is applied from the bottom. It collect | recovered and it was set as the test solution. In the case of the examples, there was no leaching of the liquid to the lower part, so the liquid remaining on the upper part after 30 minutes at 60 ° C. was used as a test solution. The test solution was taken in a platinum, quartz, or heat-resistant glass evaporating dish with a known weight previously dried at 105 ° C., and evaporated to dryness on a water bath. Subsequently, after drying at 105 degreeC for 2 hours, it stood to cool in a desiccator. After standing to cool, it weighed and calculated | required the mass difference a (mg) before and behind an evaporating dish, and calculated | required the quantity of the evaporation residue by following Formula.
Evaporation residue (μg / ml) = ((ab) × 1,000) / sample collected (ml)
Where b is the blank test value (mg) obtained for the same amount of leaching solution as the test solution.

The results are shown in Table 1 below. From Table 1, the breathable packaging material according to the present invention conforms to the standards in any of 4% acetic acid elution residue test, water resistance test, and oil resistance test, and can be used for packaging applications in contact with food. I understood.

[Section observation test]
About the packaging material of the Example and the comparative example 1, the cross-sectional photograph was image | photographed using the scanning electron microscope, and it compared and observed. The results are shown in FIGS. 8 and FIG. 9 add outlines to the boundaries of the layers constituting the packaging material based on the electron micrographs. In FIG. 8, since the fiber layer constituting the reinforcing material layer 10 bites into the perforated polyethylene layer 12, there is a portion where the perforated polyethylene layer 12 is pushed by the reinforcing material layer 10 and is raised. Visible. On the other hand, in FIG. 9, the biting of the reinforcing material layer 10 into the perforated nylon layer 17 is not visible. Based on the results of these cross-sectional observation tests, it can be reasonably inferred that the difference in layer structure caused a difference in adhesion between layers, leading to an improvement in water resistance and oil resistance.

  The breathable packaging material according to the present invention is useful as a packaging material in direct contact with food.

DESCRIPTION OF SYMBOLS 1 Breathable packaging material 5 Functional article 6 Packaging body 10 Reinforcement material layer 11 Perforated polyethylene terephthalate layer 12 Perforated polyethylene layer 13 Microporous film layer 17 Perforated nylon layer 40 Reticulated structure 50 Pore 102 Split fiber film ( Vertical web)
103 Reticulated film (horizontal web)

Claims (9)

A porous polyethylene terephthalate layer, a porous polyethylene layer, a reinforcing material layer, and a microporous film layer are laminated in this order,
The reinforcing material layer includes a first fiber layer composed of a plurality of first fibers arranged in the same direction, and a plurality of second fibers arranged in a direction different from the first fiber and in the same direction. a second fibrous layer comprising fiber of, Ri laminated or woven net structure der comprising,
Wherein at least a portion of the opening portion of the network structure, and the porous polyethylene layer, wherein and the microporous film layer that is welded, breathable packaging material.   The porous polyethylene terephthalate layer, the porous polyethylene layer, the reinforcing material layer, and the microporous film layer are thermocompression bonded at a temperature of 120 to 140 ° C. and a linear pressure of 200 to 260 N / cm. The breathable packaging material according to claim 1.   The breathable packaging material according to claim 1 or 2, wherein communication of air in a direction parallel to the surface in the reinforcing material layer is prevented.   The said network structure is a nonwoven fabric obtained by longitudinally laminating a split fiber film obtained by splitting and stretching a longitudinally uniaxially stretched multilayer polyolefin film so that the stretching directions are orthogonal to each other. The breathable packaging material according to any one of the above. A porous polyethylene terephthalate layer, a porous polyethylene layer, a reinforcing material layer, and a microporous film layer are laminated in this order,
The reinforcing material layer includes a first fiber layer composed of a plurality of first fibers arranged in the same direction, and a plurality of second fibers arranged in a direction different from the first fiber and in the same direction. The second fiber layer made of the fibers is a breathable packaging material, which is a network structure laminated or woven,
The network structure is formed by splitting a longitudinally uniaxially stretched multilayer polyolefin film and then widening it, and after forming slits in the width direction in the multilayer polyolefin film, it is uniaxially stretched in the transverse direction. A breathable packaging material , which is a nonwoven fabric obtained by laminating the obtained network film so that the stretching directions are orthogonal.   The breathable packaging material according to any one of claims 1 to 5, wherein a 4% acetic acid evaporation residue based on a standard specified by the Food Sanitation Law is 30 µg / ml or less. Laminating a porous polyethylene terephthalate layer, a porous polyethylene layer, a reinforcing material layer, and a microporous film layer in this order;
And thermocompression bonding the laminate obtained by the above process at a temperature of 120 to 140 ° C. and a linear pressure of 200 to 260 N / cm,
The reinforcing material layer includes a first fiber layer composed of a plurality of first fibers arranged in the same direction, and a plurality of second fibers arranged in a direction different from the first fiber and in the same direction. A method for producing a breathable packaging material, wherein the second fiber layer made of the fibers is a network structure formed by being laminated or woven.   A breathable packaging material according to any one of claims 1 to 6 is used for at least part of the porous polyethylene terephthalate layer, and an oxygen scavenger, desiccant, freshness-retaining agent, exothermic agent, and hygroscopic agent. A package containing a deodorant, insect repellent, dehumidifier or fragrance. The breathable packaging material according to any one of claims 1 to 6, wherein the breathable packaging material is used as at least a part thereof, and the microporous film layer is disposed inward so that both ends of the microporous film layer face each other. A step of making the material into a bag,
Storing the oxygen-absorbing agent, desiccant, freshness-retaining agent, exothermic agent, moisture-absorbing agent, deodorant, insecticide, dehumidifying agent or fragrance in the bag-like breathable packaging material;
And a step of heat-sealing a peripheral portion of the bag-shaped breathable packaging material by a hot press method.