JP6413341B2 - Multilayer structure, packaging material, and packaging bag - Google Patents

Description

  The present invention relates to a multilayer structure including a heat-adhesive resin layer, a packaging material having the multilayer structure, and a packaging bag using the packaging material.

  The packaging material is used for packaging bags for packaging food products, pharmaceuticals, and the like, and the contents of the packaging bags have various states such as liquid, powder, paste, and solid. Such a packaging bag is required to have characteristics such as strength against external force, air tightness, and unsealing property when the packaging bag is opened.

  For example, the packaging material described in Patent Document 1 has a multilayer structure including a base material layer made of a resin or the like, a barrier layer made of an aluminum foil or the like, and a thermoadhesive resin layer. In a packaging bag using such a packaging material, strength against external force is increased and airtightness is secured by a barrier layer. Furthermore, even if an adhesive is not required, the packaging bag can be sealed by thermally bonding the heat-adhesive resin layers facing each other.

  On the other hand, for example, the packaging bag described in Patent Document 2 has a notch that is a notch or a V-shaped cutout at the edge of the packaging bag. According to such a configuration, since the packaging bag can be easily opened by tearing the packaging bag starting from the notch, the opening property of the packaging bag is improved.

Japanese Patent No. 5385484 Japanese Unexamined Patent Publication No. 7-96949

  By the way, the addition of the heat-adhesive resin layer to the component of the packaging material causes an increase in force necessary for tearing and a decrease in straightness of the torn part. Therefore, the packaging material having the heat-adhesive resin layer is evaluated based on the magnitude of the force required for tearing and the straightness of the torn part, compared to the packaging material not having the heat-adhesive resin layer. Tearability is low. Therefore, there is a limit to improving the unsealing property of such a packaging bag only by providing a notch in the packaging bag formed from the packaging material having the heat-adhesive resin layer.

  The present invention provides a multilayer structure provided with a heat-adhesive resin layer, a packaging material and a packaging bag having such a multilayer structure, and a multilayer structure, a packaging material, and a packaging bag that can improve tearability. With the goal.

  A multilayer structure for solving the above-mentioned problems is a thermoadhesive resin layer having a first surface and a second surface that is a surface opposite to the first surface, and the thermal adhesive resin layer. An adjacent layer in close contact with a part of the second surface, wherein the first surface of the thermoadhesive resin layer includes a plurality of convex portions and a concave portion that is a portion between the adjacent convex portions. And the second surface of the heat-adhesive resin layer is separated from the adjacent layer in a portion located on the opposite side of the convex portion, and in the part located on the opposite side of the concave portion, Adhering to the adjacent layer.

  According to the above configuration, in the multilayer structure, the portion where the concave portion is located on the first surface of the heat-adhesive resin layer is easier to tear than the portion where the convex portion is located on the first surface. Therefore, when the multilayer structure is torn, the multilayer structure is torn through the portion where the recess is located. As a result, the position where the multilayer structure is torn is limited, and the relatively small portion of the magnitude of the force required for tearing is selectively torn, so that the tearability of the multilayer structure is improved.

  In the above configuration, the plurality of convex portions are scattered on the first surface, and any one of the plurality of convex portions is defined as the first convex portion, and the plurality of convex portions are included in the plurality of convex portions. When the convex portion closest to the first convex portion is the second convex portion, the length of the first convex portion in the direction in which the first convex portion and the second convex portion are arranged And the total length of the concave portion between the first convex portion and the second convex portion is preferably 100 μm or more and 1000 μm or less.

According to the above configuration, the tearing position of the multilayer structure can be suitably enhanced because the position at which the multilayer structure is torn is easily limited to the recess.
The said structure WHEREIN: It is preferable that the area of the said recessed part is 20% or more and 60% or less of the total area of the area of the said convex part, and the area of the said recessed part in planar view facing the said 1st surface.

  According to the said structure, since the area of a recessed part is 20% or more of the said total area, it can suppress that the area | region torn in a multilayered structure overlaps the part in which a convex part is located. As a result, the tearability of the multilayer structure is improved. In addition, since the area of the recess is 60% or less of the total area, the degree to which the position where the multilayer structure is torn is limited is sufficiently large, and the straightness of the portion torn by the multilayer structure is increased. As a result, the tearability of the multilayer structure is improved.

The said structure WHEREIN: It is preferable that the thickness of the said thermoadhesive resin layer in the part in which the said convex part is located is larger than the thickness of the said thermoadhesive resin layer in the part in which the said recessed part is located.
According to the above configuration, the thickness of the heat-adhesive resin layer is relatively increased in the portion where the convex portion that is difficult to tear, and the portion where the concave portion that is easy to tear is located, By making the thickness of the adhesive resin layer relatively small, it is possible to increase the heat seal strength when the heat adhesive resin layers are welded together while improving the tearability.

The packaging material which solves the said subject has the said multilayered structure at least in part.
According to the said structure, the tearability of a packaging material is improved at the part which has a multilayer structure at least.

The packaging bag which solves the said subject is a packaging bag formed from the said packaging material, Comprising: It has the said multilayered structure in the opening part of the said packaging bag at least.
According to the above configuration, the tearability of the packaging bag is enhanced at least at the planned opening site, so that the opening property of the packaging bag is enhanced.

  According to the present invention, tearability can be enhanced in a multilayer structure including a heat-adhesive resin layer, a packaging material having such a multilayer structure, and a packaging bag.

It is sectional drawing which shows the cross-section of the multilayer structure of one Embodiment. It is a top view which shows the planar structure of the multilayer structure of one Embodiment. It is a top view which shows the modification of the planar structure of the multilayer structure of one Embodiment. It is a perspective view which shows the perspective structure of the packaging bag of one Embodiment. In the heat-adhesive resin layer which the packaging bag of one Embodiment has, it is a figure which shows the arrangement | positioning aspect of the pattern comprised from a convex part and a recessed part, Comprising: Thermal adhesiveness of the part A enclosed by the dashed-dotted line in FIG. It is a figure which expands and shows a resin layer.

  An embodiment of a multilayer structure, a packaging material, and a packaging bag will be described with reference to FIGS. In FIG. 1 to FIG. 5, the size and shape of each part are exaggerated for convenience of explanation.

[Configuration of multilayer structure and packaging material]
As shown in FIG. 1, the multilayer structure 10 includes a base material layer 11, a barrier layer 12, and a thermal adhesive resin layer 13.

  The base material layer 11, the barrier layer 12, and the thermoadhesive resin layer 13 are arranged in this order, and the first surface of the thermoadhesive resin layer 13 constitutes the outermost surface of the multilayer structure 10, and is thermally bonded. A part of the second surface, which is the surface opposite to the first surface in the conductive resin layer 13, is in close contact with the barrier layer 12. The barrier layer 12 is sandwiched between the base material layer 11 and the thermoadhesive resin layer 13. That is, in the multilayer structure 10 in the present embodiment, the barrier layer 12 is an adjacent layer adjacent to the thermal adhesive resin layer 13.

  The base material layer 11 is a layer that functions as a support for the multilayer structure 10. As the material of the base material layer 11, for example, polyethylene, polypropylene, polyethylene terephthalate, nylon, paper, or the like is used. The base material layer 11 may be a single layer made of one of the above materials, or may be a layer in which a plurality of the above materials are combined by stacking such single layers.

  The barrier layer 12 is a layer having a function of improving the barrier property of gas or liquid. As a material of the barrier layer 12, for example, a metal such as aluminum is used. The barrier layer 12 is formed, for example, by depositing a metal on the base material layer 11 or laminating a metal foil on the base material layer 11 by a laminating process.

  The heat-adhesive resin layer 13 is a layer that contributes to making a packaging bag by welding the heat-adhesive resin layers 13 together. The material of the heat-adhesive resin layer 13 is preferably a thermoplastic resin having an appropriate flexibility and having a good workability such as, for example, a processability by an extruder. Examples of such materials include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene, ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl. An acrylate copolymer (EBA), an ethylene-methacrylic acid copolymer (EMAA), etc. are mentioned. These materials may be used alone, or a plurality of these materials may be used in combination. The heat-adhesive resin layer 13 is laminated on the barrier layer 12 by being adhered to the barrier layer 12 by an adhesive or by being laminated on the barrier layer 12 by laminating.

  The heat-adhesive resin layer 13 has a plurality of convex portions 14 projecting on the first surface and a concave portion 15 that is a portion between the convex portions 14 adjacent to each other. Each of the plurality of convex portions 14 protrudes along the direction in which the layers constituting the multilayer structure 10 are arranged, and is scattered on the first surface of the thermoadhesive resin layer 13. Due to the plurality of convex portions 14 and the concave portions 15, the first surface of the thermoadhesive resin layer 13 has an uneven structure.

  On the second surface of the thermoadhesive resin layer 13, the portion located on the opposite side of the convex portion 14 is separated from the barrier layer 12 facing the thermoadhesive resin layer 13. On the other hand, on the second surface of the thermoadhesive resin layer 13, the part located on the opposite side to the recess 15 is in close contact with the barrier layer 12 facing the thermoadhesive resin layer 13. And between the thermoadhesive resin layer 13 and the barrier layer 12, the space | gap surrounded by the site | part located on the opposite side to the convex part 14 in the 2nd surface of the thermoadhesive resin layer 13, and the barrier layer 12 is enclosed. S is formed.

  In the portion of the second surface of the multilayer structure 10 located on the side opposite to the recess 15, the heat-adhesive resin layer 13 and the barrier layer 12 are in close contact, and the barrier layer 12 and the base material layer 11 are in close contact. Yes. Therefore, when the multilayer structure 10 is torn, the thermoadhesive resin layer 13, the barrier layer 12, and the base material layer 11 follow the layers having relatively high tearability among these layers. Torn. Therefore, the portion where the concave portion 15 is located on the outermost surface in the multilayer structure 10 is the portion where the heat-adhesive resin layer 13 and the barrier layer 12 are separated, that is, the convex portion on the outermost surface in the multilayer structure 10. It is easy to tear compared with the part in which 14 is located.

  Depending on whether the heat-adhesive resin layer 13 and the barrier layer 12 are in close contact with each other, the tearability of the portion where the convex portion 14 is located on the outermost surface and the ease of tearing the portion where the concave portion 15 is located on the outermost surface There is a sufficient difference. Therefore, when the multilayer structure 10 is torn, when the tip of the portion where the tearing proceeds reaches the portion where the convex portion 14 is located, the tip is moved from the portion where the convex portion 14 is located. The tearing proceeds by shifting to the portion where the surrounding concave portion 15 is located. As a result, the multilayer structure 10 is torn so as to pass through the portion where the recess 15 is located on the outermost surface.

  According to such a configuration, the tearing position of the multilayer structure 10 is limited, and therefore, the direction in which tearing proceeds is suppressed from varying in multiple directions as compared to the case where there is no such limitation. In addition, since the portion where the concave portion 15 is located on the outermost surface, that is, the portion where the magnitude of the force necessary for tearing is relatively small is selectively torn, the magnitude of force necessary for tearing may increase. It can be suppressed. Therefore, the tearability of the multilayer structure 10 is improved.

  In the direction in which the layers in the multilayer structure 10 are arranged, the thickness d1 of the portion of the thermal adhesive resin layer 13 where the convex portion 14 is located on the outermost surface is the thickness d1 of the portion of the thermal adhesive resin layer 13 where the concave portion 15 is located on the outermost surface. The thickness d2 is preferably larger than the thickness d2, and the thickness d2 is more preferably 60% or less of the thickness d1.

  In order to improve the tearability, it is preferable that the thickness of the heat-adhesive resin layer 13 is small. On the other hand, in order to increase the heat-sealing strength of the heat-sealed part, which is a welded part in the packaging bag, the heat-adhesive resin layer 13 is welded. The thickness of the heat-adhesive resin layer 13 is preferably large enough to ensure a sufficient amount of resin. Therefore, the thickness d2 of the heat-adhesive resin layer 13 is relatively reduced at the portion where the concave portion 15 is torn, and the portion at which the convex portion 14 is located which is not torn is thermally bonded. By making the thickness d1 of the conductive resin layer 13 relatively large, the heat seal strength can be increased while improving the tearability.

  Further, from the viewpoint of balancing the improvement in heat seal strength and the reduction in material cost that increases with the amount of resin, the thickness d1 of the heat-adhesive resin layer 13 in the portion where the convex portion 14 is located is 10 μm or more and 50 μm or less. The thickness d2 of the heat-adhesive resin layer 13 in the portion where the recess 15 is located is preferably 5 μm or more and 30 μm or less.

  If the gap S has a size that does not allow at least the thermal adhesive resin layer 13 and the barrier layer 12 to contact, the gap S is easily torn at the portion where the convex portion 14 is located and the portion where the concave portion 15 is located. It is possible to ensure a difference in height. Therefore, the thickness ds of the gap S in the stacking direction of the multilayer structure 10 is preferably smaller than the thickness d1 of the heat-adhesive resin layer 13 in the portion where the convex portion 14 is located on the outermost surface.

  As shown in FIG. 2, when viewed from the direction facing the first surface of the heat-adhesive resin layer 13, the convex portion 14 has, for example, a substantially rectangular shape, and the X direction is perpendicular to the X direction. Lined up along the direction. At this time, the recess 15 has a lattice shape in which a straight line extending along the X direction and a straight line extending along the Y direction intersect at a right angle.

  In the X direction, the total length of the length W1 of the convex portion 14 and the length L1 of the concave portion 15 between the convex portion 14 and the other convex portion 14 closest to the convex portion 14 is: The pitch P1 in the X direction. When the length W1 for each convex portion 14 is constant and the pitch P1 for each convex portion 14 is constant, the pitch P1 is the length of one cycle of the pattern repeated along the X direction.

  In the Y direction, the total length of the length W2 of the convex portion 14 and the length L2 of the concave portion 15 between the convex portion 14 and the other convex portion 14 closest to the convex portion 14 is: The pitch P2 in the Y direction. When the length W2 for each convex portion 14 is constant and the pitch P2 for each convex portion 14 is constant, the pitch P2 is the length of one cycle of the pattern repeated along the Y direction.

  The pitch P1 in the X direction is preferably 100 μm or more and 1000 μm or less, and the pitch P2 in the Y direction is also preferably 100 μm or more and 1000 μm or less. The pitch P1 in the X direction and the pitch P2 in the Y direction may be equal to each other or different from each other. Regardless of whether the pitch P1 and the pitch P2 are equal to each other, the length W1 of the convex portion 14 in the X direction and the length W2 of the convex portion 14 in the Y direction may be equal to each other, Further, the length L1 of the recess 15 in the X direction and the length L2 of the recess 15 in the Y direction may be equal to each other or different from each other.

  When the pitches P1 and P2 are 100 μm or more, the pitches P1 and P2 are sufficiently larger than the width occupied by the linear part that is the area to be torn in the multilayer structure 10, so the linear part is It is suppressed that it overlaps with both the part in which the convex part 14 is located, and the part in which the recessed part 15 is located. As a result, since the portion where the convex portion 14 is located, that is, the portion that requires a relatively large force for tearing, is prevented from being torn, an increase in the amount of force necessary for tearing can be suppressed. Therefore, the tearability of the multilayer structure 10 is improved.

  Further, when the pitches P1 and P2 are 1000 μm or less, even when the multilayer structure 10 is torn from an arbitrary position, the concave portion 15 is positioned in the immediate vicinity of the place where the force for tearing is applied. The portion where the recess 15 is located tends to be the starting point of tearing. Therefore, the tearability can be improved at an arbitrary position of the multilayer structure 10 without specifying the tear starting point in advance.

  In a plan view facing the first surface of the thermoadhesive resin layer 13, the area of the recess 15 is 20% or more and 60% or less of the total area of the area of the protrusion 14 and the area of the recess 15. It is preferable. If the area of the recess 15 is 20% or more of the total area, the area of the recess 15 with respect to the protrusion 14 is sufficiently large, so that the region to be torn of the multilayer structure 10 is the protrusion 14. It is suppressed that it overlaps with the part which is located. As a result, the tearability of the multilayer structure 10 is improved. Further, when the area of the recess 15 is 60% or less of the total area, the degree to which the position to which the multilayer structure 10 is torn is limited is sufficiently large, so that the straightness of the torn part is improved. As a result, the tearability of the multilayer structure 10 is improved.

  In the X direction, the length W1 of the convex portion 14 may be different for each convex portion 14, and the length L1 of the concave portion 15 may be different for each adjacent convex portion 14. Good. Further, the pitch P1 in the X direction may be different for each convex portion 14. Similarly, in the Y direction, the length W2 of the convex portion 14 may be different for each convex portion 14, and the length L2 of the concave portion 15 is different for each convex portion 14 adjacent to each other. Also good. Further, the pitch P2 in the Y direction may be different for each convex portion 14.

  In addition, the shape of the recess 15 does not have to be a lattice shape in a plan view facing the first surface of the thermoadhesive resin layer 13. For example, as shown in FIG. 3, the plurality of convex portions 14 may not be arranged in a straight line in the Y direction. Similarly, the plurality of convex portions 14 may not be arranged in a straight line in the X direction. Furthermore, the plurality of convex portions 14 may be irregularly arranged regardless of the X direction and the Y direction.

  Further, in the plan view facing the first surface of the thermal adhesive resin layer 13, the shape of the convex portion 14 is not limited to the rectangular shape, and may be a polygonal shape different from the rectangular shape, or a circular shape, It may be a shape surrounded by a straight line or a curve or a straight line and a curve. Moreover, the some convex part 14 may have a mutually different shape.

  In short, in the multilayer structure 10, the difference between whether the portion where the convex portion 14 is located on the outermost surface and the portion where the concave portion 15 is located is in close contact with the thermal adhesive resin layer 13 and the barrier layer 12. Since the position where the multilayer structure 10 is torn is limited, the tearability is improved compared to the case where there is no such limitation. Even when the protrusions 14 are irregularly arranged, the length corresponding to the pitches P1 and P2 may be 100 μm or more and 1000 μm or less in order to appropriately obtain the effect of improving the tearability. preferable. That is, when any one convex portion 14 is the first convex portion 14 and the convex portion 14 closest to the first convex portion 14 is the second convex portion 14, the first convex portion 14 and the second convex portion 14 The total length of the length of the first convex portion 14 and the length of the concave portion 15 between the first convex portion 14 and the second convex portion 14 in the direction in which the convex portions 14 are arranged is 100 μm or more and 1000 μm or less is preferable. According to such a configuration, the tearing position of the multilayer structure 10 is appropriately limited, so that the tearability of the multilayer structure 10 is preferably improved.

  However, from the viewpoint of facilitating the design of the pattern constituted by the convex portions 14 and the concave portions 15 and the manufacture of the mold used for forming the concavo-convex structure, the scattered convex portions 14 are regularly arranged, and the pattern is It is preferable to have periodicity. In particular, as shown in FIG. 2, a plurality of convex portions 14 having the same rectangular shape are arranged along the X direction and the Y direction, and the concave portion 15 has a lattice shape, and the pitch P1 and the pitch P2 are Are preferably equal.

  The concavo-convex structure constituted by the convex portions 14 and the concave portions 15 is formed using an embossing roll having a shape obtained by inverting the concavo-convex structure of the concavo-convex structure when the heat-adhesive resin layer 13 is formed by extrusion molding, for example. It is formed by doing. The concavo-convex structure is not limited to extrusion molding and may be formed by a known method.

  The multilayer structure 10 may include other layers in addition to the base material layer 11, the barrier layer 12, and the thermal adhesive resin layer 13. The point is that the heat-adhesive resin layer 13 is separated from the layer adjacent to the heat-adhesive resin layer 13 at the part opposite to the convex part 14 and the part opposite to the concave part 15. If the heat-adhesive resin layer 13 is in close contact with the layer adjacent to the heat-adhesive resin layer 13, the effect of improving the tearability of the multilayer structure 10 can be obtained.

  Moreover, each of the base material layer 11, the barrier layer 12, and the thermoadhesive resin layer 13 may contain various additives in addition to the above-described materials. As an additive, an additive generally used as an additive for a film or a sheet can be used for improving processability at the time of molding and suitability at the time of use. For example, an additive such as an anti-blocking agent such as a filler or a lubricant for improving lubricity may be added to the material of the layer in order to impart processing stability.

  The packaging material is a sheet having the multilayer structure 10 described above in at least a part of the packaging material. The packaging material has the multilayer structure 10 at least at a site to be torn when a packaging bag is formed from the packaging material. For example, the packaging material has the multilayer structure 10 at a site used for the opening position of the packaging bag. Moreover, another layer may be laminated | stacked on the above-mentioned multilayer structure 10, and a packaging material may be formed.

[Composition of packaging bag]
With reference to FIG. 4 and FIG. 5, the packaging bag formed using the packaging material which has the above-mentioned multilayered structure 10 is demonstrated. In the following, an example in which the entire packaging material is composed only of the multilayer structure 10 will be described.

  As shown in FIG. 4, the packaging bag 20 is formed in a sealed bag shape. The contents are accommodated inside the packaging bag 20. The content is not particularly limited, and the content may be liquid, solid, powder, or paste. The size and shape of the packaging bag 20 are not particularly limited and may be determined according to the contents.

  In the packaging bag 20, the thermoadhesive resin layer 13 faces the inside of the packaging bag 20, and the base material layer 11 faces the outside of the packaging bag 20. The packaging bag 20 has a heat seal portion 21 at the edge of the packaging bag 20. The heat seal portion 21 is formed by welding the heat adhesive resin layers 13 facing each other. For example, the heat-adhesive resin layers 13 facing each other are melted and adhered by being heated and pressed, and the heat seal portion 21 is formed. By forming the heat seal portion 21, the packaging bag 20 is sealed.

  In addition, the position of the heat seal part 21 should just be determined according to the form of the packaging bag 20, the aspect of the bag making from the packaging material to the packaging bag 20, etc., and the packaging bag 20 is the edge part of 20 of a packaging bag. It suffices to have the heat seal part 21 at least in part.

  With reference to FIG. 5, the arrangement | positioning aspect of the pattern comprised from the convex part 14 and the recessed part 15 is demonstrated. 5 shows one of the two heat-adhesive resin layers 13 facing each other in the vicinity of the heat-seal portion 21, with the convex portions 14 and the concave portions 15 in a plan view facing the first surface of the heat-adhesive resin layer 13. The arrangement is shown. In the heat seal part 21, the convex part 14 and the concave part 15 are joined to the convex part 14 and the concave part 15 of the other thermoadhesive resin layer 13 facing each other. Hereinafter, an example in which the pattern shown in FIG. 2 is formed by the convex portion 14 and the concave portion 15 will be described.

  As shown in FIG. 5, the inner peripheral edge of the heat seal portion 21, that is, the portion of the heat-adhesive resin layer 13 that is welded to form the heat seal portion 21, and the inner surface of the packaging bag 20 without being welded. A boundary with a constituent part is defined as a boundary M. The pattern composed of the convex portion 14 and the concave portion 15 is arranged so that the X direction and the Y direction in the pattern are different from the direction in which the boundary M extends.

  At this time, the lattice shape of the recess 15 is inclined with respect to the direction in which the boundary M extends, and the direction in which the recess 15 extends, that is, the direction in which the straight lines constituting the lattice shape extend is the direction in which the boundary M extends. Different.

  In such a configuration, when a shearing force is applied to the outer peripheral edge of the packaging bag 20, that is, the outer peripheral edge of the heat seal portion 21, at a position indicated by a two-dot chain line F, a multilayer structure is formed. The body 10 is torn so as to pass through a portion where the concave portion 15 is located by sewing between the plurality of convex portions 14 as indicated by a broken line X, for example. The position of the broken line X is an example, and changes depending on the direction in which a force to tear the packaging bag 20 is applied.

  Here, the inner peripheral edge and the outer peripheral edge of the heat seal part 21 are usually arranged in parallel. Therefore, the shortest path connecting the inside and the outside of the packaging bag 20 is a linear path extending from the boundary M toward the outer peripheral edge of the heat seal portion 21 in a direction orthogonal to the direction in which the boundary M extends. In the above configuration, since the X direction and the Y direction of the pattern formed by the convex portions 14 and the concave portions 15 are different directions from the direction in which the boundary M extends, the direction in which the convex portions 14 are arranged most closely extends the shortest path. Does not match the direction. Further, the extending direction of the recess 15 does not coincide with the extending direction of the shortest path.

  For example, when the packaging bag 20 falls in a state in which a content such as fluid is included, the force that the packaging bag 20 receives from the content is in a direction in which the heat-adhesive resin layers 13 are peeled off from the heat seal portion 21. Works. At this time, the bonding strength of the portion including the recess 15 in the heat seal portion 21 tends to be lower than that of other portions in the heat seal portion 21. In this regard, as described above, if the configuration in which the extending direction of the recess 15 does not coincide with the extending direction of the shortest path, thermal bonding is performed as compared with the configuration in which the extending direction of the recess 15 and the extending direction of the shortest path match. The resistance against external force that tries to peel off the conductive resin layers 13 is increased, and the sealed state of the packaging bag 20 is prevented from being broken.

  Further, due to the impact such as dropping being applied to the packaging bag 20, the structure between the adjacent convex portions 14 collapses and a defect occurs in the parallel structure of the convex portions 14, or the inner peripheral side of the heat seal portion 21. Even if a defect such as a crack occurs in the recess 15, it is possible to suppress such a defect from proceeding along the shortest path. Therefore, as compared with the case where the defect is likely to travel along the shortest path as in the case where the convex portions 14 are aligned most closely or the extending direction of the concave portion 15 coincides with the extending direction of the shortest path, This prevents the inside and outside of the packaging bag 20 from communicating and the sealed state of the packaging bag 20 from being broken.

  The packaging bag 20 may be formed from a packaging material having the multilayer structure 10 in part. In this case, at least a portion of the packaging bag 20 that is to be torn when the packaging bag 20 is opened. The part which has the multilayer structure 10 of a packaging material should just be arrange | positioned in a certain opening expected site | part. According to such a configuration, the tearability of the packaging bag 20 is enhanced at least at the planned opening site, and as a result, the opening property of the packaging bag 20 is enhanced.

  Moreover, the packaging bag 20 may have a notch which is a notch or a V-shaped notch at the edge. By tearing the packaging bag 20 starting from the notch, the force required for tearing at the start of opening is reduced, so that the packaging bag 20 can be opened more easily. And in the packaging bag 20 having the multilayer structure 10 of the present embodiment, the force required for tearing not only at the start of opening but also during the opening of the opening due to the structure having the above-described convex portions 14 and concave portions 15. Is reduced, and the straightness of the progress of tearing is enhanced, so that the opening of the packaging bag 20 is effectively enhanced. Therefore, it takes time to open the packaging bag, or excessive force is applied to open the packaging bag, the packaging bag is opened suddenly, the contents are spilled, or the packaging bag is opened in an unintended direction, making it difficult to take out the contents. Is suppressed.

As described above, according to the multilayer structure, the packaging material, and the packaging bag of the present embodiment, the effects listed below can be obtained.
(1) In the multilayer structure 10, the thermoadhesive resin layer 13 has, on the first surface, a plurality of protrusions 14 and a recess 15 that is a portion between the plurality of protrusions 14. The second surface of the heat-adhesive resin layer 13 is separated from the barrier layer 12 at the portion where the convex portion 14 is located on one surface, and the heat-adhesive resin layer at the portion where the concave portion 15 is located on the first surface. The second surface 13 is in close contact with the barrier layer 12. According to such a configuration, in the multilayer structure 10, the portion where the concave portion 15 is located on the outermost surface is easier to tear than the portion where the convex portion 14 is located on the outermost surface. Torn through the portion where the recess 15 is located. As a result, the position at which the multilayer structure 10 is torn is limited, and the relatively small portion of the magnitude of the force required for tearing is selectively torn, so that the tearability of the multilayer structure 10 is enhanced. . Thereby, also in the packaging material which has the multilayered structure 10, and the packaging bag 20 formed from a packaging material, tearability is improved.

  Moreover, the position and direction where the multilayer structure 10 is torn can be adjusted by adjusting the arrangement of the convex portions 14 and the concave portions 15. In this case, the concave portion 15 may be disposed at a portion desired to be torn and the convex portion 14 may be disposed around the concave portion 15.

  Moreover, since the uneven structure is formed in the 1st surface of the thermoadhesive resin layer 13, the lubricity of a packaging material, such as when the packaging bag 20 is formed, is improved. As a result, the productivity of the packaging bag 20 can be improved.

  (2) When the pitches P1 and P2 between the convex portion 14 and the concave portion 15 are 100 μm or more, the region to be torn by the multilayer structure 10 is both a portion where the convex portion 14 is located and a portion where the concave portion 15 is located. It can be suppressed to overlap. Therefore, an increase in the magnitude of force required for tearing can be suppressed. Further, when the pitches P1 and P2 are 1000 μm or less, good tearability can be obtained even when the multilayer structure 10 is torn from an arbitrary position. As described above, the tearing position of the multilayer structure 10 is appropriately limited, so that the tearability of the multilayer structure 10 is preferably improved.

  (3) When the area of the recess 15 is 20% or more of the total area of the area of the protrusion 14 and the area of the recess 15, the region to be torn by the multilayer structure 10 is a portion where the protrusion 14 is positioned. It can be suppressed to overlap. In addition, when the area of the recess 15 is 60% or less of the total area, the degree to which the position where the multilayer structure 10 is torn is limited is sufficiently large, and the portion is torn by the multilayer structure 10. The straightness of the is improved. As a result, the tearability of the multilayer structure 10 is enhanced by the above configuration.

  (4) The thickness d1 of the heat-adhesive resin layer 13 is relatively increased in the portion where the convex portion 14 is a portion that is difficult to tear, and in the portion where the concave portion 15 is the portion that is easily torn, By making the thickness d2 of the heat-adhesive resin layer 13 relatively small, it is possible to increase the heat seal strength when the heat-adhesive resin layers 13 are welded together while improving the tearability.

  (5) In the packaging material having the multilayer structure 10, the tearability of the packaging material is enhanced at least in the portion having the multilayer structure 10. And the packaging bag 20 formed from such a packaging material has the multilayered structure 10 in the opening plan part of the packaging bag 20 at least, and the tearability of the packaging bag 20 is improved at least in the opening plan part. As a result, the openability of the packaging bag is improved.

The multilayer structure, the packaging material, and the packaging bag described above will be described using specific examples and comparative examples.
[Test for presence of uneven structure and thickness of heat-adhesive resin layer]
Example 1
The substrate layer 11 is made by sand lamination using PET having a thickness of 12 μm as the substrate layer 11, using an aluminum foil having a thickness of 7 μm as the barrier layer 12, and sandwiching 15 μm thick polyethylene between the substrate layer 11 and the barrier layer 12. A barrier layer 12 was laminated thereon. Furthermore, EMAA was laminated on the barrier layer 12 as a heat-adhesive resin layer 13 by extrusion lamination. At this time, using an embossing roll having irregularities on the surface, as shown in FIG. 2, the protrusions 14 are formed in the X direction and the Y direction on the upper surface, which is the first surface of the thermal adhesive resin layer 13. A pattern in which the recesses 15 are regularly arranged and have a lattice shape is formed. Thereby, the multilayer structure 10 of Example 1 was obtained.

  By observing the cross-sectional structure of the multilayer structure 10 of Example 1, it was confirmed that the void S was formed in the convex portion 14. The presence or absence of the gap S is determined by cutting the multilayer structure 10 and then checking the cross section with an optical microscope (Microscope manufactured by Keyence (model number: VHX-1000)) and a laser microscope (Laser manufactured by Keyence). It confirmed with two methods of the method of confirming with a microscope (model number: VK-X200). The void S was confirmed by either of these two methods. In addition, about all the following examples and comparative examples, the presence or absence of the space | gap S was confirmed by the above-mentioned two methods, but there was no big difference in the result by two methods.

  Of the direction in which the convex portions 14 are arranged, one direction is the X direction, and the direction perpendicular to the X direction is the Y direction, and the pitches P1 and P2, the lengths L1 and L2 of the concave portions 15, and the thermal adhesive resin layer 13 The thicknesses d1 and d2 were measured using the laser microscope described above. As a result, P1 = P2 = 300 μm, L1 = L2 = 60 μm, and d1 = d2 = 15 μm. The recess area ratio, which is the ratio of the area of the recess 15 to the total area of the protrusion 14 and the recess 15, is calculated using the pitches P 1 and P 2 and the lengths L 1 and L 2 of the recess 15. About 36%.

(Example 2)
In the manufacturing method of Example 1, the surface shape and the resin amount of the embossing roll used in the extrusion laminating are changed, the thickness d1 of the heat-adhesive resin layer 13 in the convex portion 14 is 25 μm, and the heat-adhesive resin layer in the concave portion 15 A multilayer structure 10 of Example 2 having the same configuration as that of Example 1 was obtained except that the thickness d2 of 13 was 15 μm.

(Comparative Example 1)
In the manufacturing method of Example 1, a comparative example having the same configuration as that of Example 1 except that a roll having no unevenness on the surface by extrusion lamination is used and the heat-adhesive resin layer 13 is a flat layer having a thickness of 15 μm. The multilayer structure 10 of Example 1 was obtained.

<Evaluation method>
About the multilayer structure 10 of Examples 1, 2 and Comparative Example 1, tearability and heat seal strength were evaluated. As evaluation of tearability, measurement of tear strength and evaluation of straightness of tearing were performed.

(Tear strength)
The tear strength was measured at a pulling rate of 200 mm / min using a Shimadzu Corporation tensile tester (model number AGS-500NX) according to the trouser tear method in accordance with JIS K 7128-1.

(Tear straightness)
With respect to the multilayer structure 10 that was torn during the measurement of the tear strength, the difference between the torn part and the straight line extending in the direction perpendicular to the tensile direction from the position where tearing was started was measured. Samples in which this deviation was within 5 mm were marked with ◎, samples with more than 5 mm within 10 mm, and samples with more than 10 mm marked with x.

(Heat seal strength)
Using a heat sealer (model number TP-701-B) manufactured by Tester Sangyo Co., Ltd., with a sealing pressure of 0.2 MPa, a sealing time of 1 second, a sealing width of 10 mm, a sealing temperature of 110 ° C. and 130 ° C., The heat-adhesive resin layers 13 facing each other were welded. The welded multilayer structure 10 is pulled by hand, the heat-seal strength is remarkably weak, and a sample in which the bonding of the heat-adhesive resin layer 13 is easily released is x. Samples with good heat-seal strength were marked with ◯, and samples with good heat-seal strength even when pulled with a strong force were marked with 引 張.

  For Examples 1 and 2 and Comparative Example 1, data relating to the structures of the convex portions 14 and the concave portions 15 are shown in Table 1, and evaluation results of tear strength, tear straightness, and heat seal strength are shown in Table 2. In addition, the comprehensive judgment was evaluated as “good” for a sample having a tear strength smaller than that of Comparative Example 1, a straight tearing ability of “◯” or “◎”, and a heat seal strength of “◯” or “◎”.

表２に示されるように、凸部１４の位置する部分にて空隙Ｓの形成された実施例１，２では、いずれも、こうした凸部１４を有さない比較例１と比較して、引裂き強度が小さくなり、かつ、引裂き直進性が向上した。したがって、凸部１４の位置する部分にて空隙Ｓが形成されていることによって、多層構造体１０の引裂き性が向上することが示された。

As shown in Table 2, in Examples 1 and 2 in which the gap S is formed in the portion where the convex portion 14 is located, both are torn compared to Comparative Example 1 having no such convex portion 14. Strength decreased and tear straightness improved. Therefore, it was shown that the tearability of the multilayer structure 10 is improved by forming the gap S at the portion where the convex portion 14 is located.

  Further, in Example 2 in which the thickness of the thermal adhesive resin layer 13 in the portion where the convex portion 14 is located is larger than the thickness of the thermal adhesive resin layer 13 in the portion where the concave portion 15 is located, there is no difference in these thicknesses. Compared to Example 1, the heat seal strength was improved. Therefore, it was shown that when the thickness of the heat-adhesive resin layer 13 is larger at the convex portion 14 than at the concave portion 15, the heat seal strength is improved.

[Test on pitch of uneven structure]
(Example 3)
Implementation having the same configuration as in Example 1 except that the surface shape of the embossing roll used in the extrusion lamination is changed in the manufacturing method of Example 1 and P1 = P2 = 30 μm and L1 = L2 = 6 μm. The multilayer structure 10 of Example 3 was obtained.

Example 4
Implementation having the same configuration as in Example 1 except that the surface shape of the embossing roll used in the extrusion lamination is changed in the manufacturing method of Example 1 and P1 = P2 = 100 μm and L1 = L2 = 20 μm. The multilayer structure 10 of Example 4 was obtained.

(Example 5)
Implementation having the same configuration as in Example 1 except that the surface shape of the embossing roll used in the extrusion lamination is changed in the manufacturing method of Example 1 and P1 = P2 = 1000 μm and L1 = L2 = 200 μm. The multilayer structure 10 of Example 5 was obtained.

(Example 6)
In the manufacturing method of Example 1, the surface shape of the embossing roll used in the extrusion laminating is changed, and P1 = P2 = 3000 μm and L1 = L2 = 600 μm. The multilayer structure 10 of Example 6 was obtained.

  About Examples 3-6, the data regarding the structure of the convex part 14 and the recessed part 15 are shown in Table 3, and the tear strength evaluated by the method similar to the above-mentioned evaluation method, tear straightness, and the evaluation result of heat seal strength are shown. Table 4 shows. For comparison, Table 3 and Table 4 also show the results for Example 1. The overall judgment was made based on the same criteria as those in Table 2 above. In addition, about Example 6, since the dispersion | variation in the result in a some sample was large about each of tearing strength and tearing rectilinearity, the range of the best result and the worst result is shown.

表４に示されるように、互いに異なるピッチの凹凸構造を有する実施例１，３〜６のうち、ピッチが１００μｍ以上１０００μｍ以下である実施例１，４，５では、上述の比較例１に対して、引裂き強度の低下と引裂き直進性の向上とが顕著であった。したがって、ピッチが１００μｍ以上１０００μｍ以下であると、多層構造体１０の引裂き性が顕著に向上することが示された。

As shown in Table 4, among Examples 1, 3 to 6 having concavo-convex structures having different pitches, Examples 1, 4 and 5 having a pitch of 100 μm or more and 1000 μm or less are compared with Comparative Example 1 described above. Thus, the reduction in the tear strength and the improvement in the straightness of tearing were remarkable. Therefore, it was shown that the tearability of the multilayer structure 10 is significantly improved when the pitch is 100 μm or more and 1000 μm or less.

  On the other hand, in Example 3 where the pitch was less than 100 μm, the tear strength was slightly smaller than that of Comparative Example 1, and although an improvement in tearability with respect to the tear strength was observed, an improvement in tear straightness was not confirmed. This is presumably because the portion where the convex portion 14 is located is also torn due to the small pitch.

  Further, in Example 6 in which the pitch exceeds 1000 μm, both the tear strength and the straightness of tearing vary, and there are samples with low tearing strength and good straightness of tearing, while the tearing strength is large and the straightness of tearing is good. There was also a bad sample. In Example 6, when the position where tearing is started is a portion where the recess 15 is located due to the large pitch, the tearing strength is small and the straightness of tearing is good, while the position where tearing is started is When the convex portion 14 is located, it is considered that the tear strength is large and the straightness of tearing is poor. Therefore, for example, if the position at which tearing is started is set in the portion where the recess 15 is located by preliminarily specifying the position at which tearing starts, good tearability can be obtained also in the sixth embodiment.

[Test on recess area ratio]
(Example 7)
In the production method of Example 1, the surface shape of the embossing roll used in the extrusion lamination was changed, except that P1 = P2 = 300 μm, L1 = L2 = 24 μm, and the recess area ratio was 15%. A multilayer structure 10 of Example 7 having the same configuration as that of Example 7 was obtained.

(Example 8)
In the production method of Example 1, the surface shape of the embossing roll used in the extrusion lamination was changed, except that P1 = P2 = 300 μm, L1 = L2 = 32 μm, and the recess area ratio was 20%. A multilayer structure 10 of Example 8 having the same configuration as that of Example 8 was obtained.

Example 9
In the production method of Example 1, the surface shape of the embossing roll used in the extrusion lamination was changed, except that P1 = P2 = 300 μm, L1 = L2 = 85 μm, and the recess area ratio was 49%. A multilayer structure 10 of Example 9 having the same configuration as that of Example 9 was obtained.

(Example 10)
In the production method of Example 1, the surface shape of the embossing roll used in the extrusion lamination was changed, except that P1 = P2 = 300 μm, L1 = L2 = 110 μm, and the recess area ratio was 60%. A multilayer structure 10 of Example 10 having the same configuration as that of Example 10 was obtained.

(Example 11)
In the production method of Example 1, the surface shape of the embossing roll used in the extrusion laminating was changed, except that P1 = P2 = 300 μm, L1 = L2 = 130 μm, and the recess area ratio was 68%. A multilayer structure 10 of Example 11 having the same configuration as that of Example 11 was obtained.

  About Examples 7-11, the data regarding the structure of the convex part 14 and the recessed part 15 are shown in Table 5, and the evaluation result of tear strength evaluated by the method similar to the above-mentioned evaluation method, tear straightness, and heat seal strength is shown. Table 6 shows. For comparison, Tables 5 and 6 also show the results for Example 1. The overall judgment was made based on the same criteria as those in Table 2 above.

表６に示されるように、凹部面積率が２０％以上６０％以下である実施例１，８〜１０では、引裂き強度は０．８Ｎ以下であり、かつ、引裂き直進性は特に良好であって、比較例１に対して、引裂き強度の低下と引裂き直進性の向上とが顕著であった。一方、凹部面積率が２０％未満である実施例７、および、凹部面積率が６０％を超える実施例１１では、比較例１よりも引裂き強度の低下と引裂き直進性の向上とが認められたものの、実施例１，８〜１０の結果には及ばなかった。したがって、凹部面積率が２０％以上６０％以下であると、多層構造体１０の引裂き性が顕著に向上することが示された。

As shown in Table 6, in Examples 1 and 8 to 10 in which the recess area ratio is 20% or more and 60% or less, the tear strength is 0.8 N or less, and the tear straightness is particularly good. Compared with Comparative Example 1, the reduction in tear strength and the improvement in tear straightness were significant. On the other hand, in Example 7 in which the recess area ratio was less than 20% and in Example 11 in which the recess area ratio exceeded 60%, a reduction in tear strength and an improvement in tear straightness were observed as compared with Comparative Example 1. However, it did not reach the results of Examples 1 and 8 to 10. Therefore, it was shown that the tearability of the multilayer structure 10 is significantly improved when the recess area ratio is 20% or more and 60% or less.

  DESCRIPTION OF SYMBOLS 10 ... Multilayer structure, 11 ... Base material layer, 12 ... Barrier layer, 13 ... Thermal-adhesive resin layer, 14 ... Convex part, 15 ... Concave part, 20 ... Packaging bag, 21 ... Heat seal part, S ... Space | gap.

Claims (5)

A heat-adhesive resin layer having a first surface and a second surface opposite to the first surface;
An adjacent layer in close contact with a part of the second surface of the thermal adhesive resin layer;
With
The first surface of the thermal adhesive resin layer is:
A plurality of convex portions and a concave portion that is a portion between the convex portions adjacent to each other;
The second surface of the thermal adhesive resin layer is:
Away from the adjacent layer at a site located on the opposite side of the convex part,
In close contact with the adjacent layer in the part located on the opposite side of the recess ,
The thickness of the said thermoadhesive resin layer in the part in which the said convex part is located is a multilayer structure larger than the thickness of the said thermoadhesive resin layer in the part in which the said recessed part is located . The plurality of convex portions are scattered on the first surface,
Arbitrary one said convex part is made into the 1st convex part in the said several convex part,
When the convex portion closest to the first convex portion is a second convex portion among the plurality of convex portions,
In the direction in which the first convex portion and the second convex portion are aligned, the length of the first convex portion and the length of the concave portion between the first convex portion and the second convex portion The multilayer structure according to claim 1, wherein a total length of the multi-layer structure is 100 μm or more and 1000 μm or less. 3. The multilayer according to claim 1, wherein an area of the concave portion is 20% or more and 60% or less of a total area of the area of the convex portion and the area of the concave portion in a plan view facing the first surface. Structure. The packaging material which has the multilayer structure as described in any one of Claims 1-3 in at least one part. A packaging bag formed from the packaging material according to claim 4 ,
A packaging bag having the multilayer structure at least at a site to be opened of the packaging bag.

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