JP2005047234A - Packaging material containing reinforcing layer and packaging bag using this packaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging material which shows successful linear tearing strength and a strength to sufficiently withstand a heavy load even when packed with the material and a packaging bag. <P>SOLUTION: The packaging material 1 has a reinforcing layer 3, and a face layer 2 and a back layer 4 laminated on both surfaces of the reinforcing layer 3 respectively. The reinforcing layer 3 is constituted by laminating a laminate layer on a reticular structure, which is formed by stretching a thermoplastic resin in one direction and combining stretched elements of respectively different shear strength in the way that their stretching directions are orthogonal with each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a packaging material containing a reinforcing layer and a packaging bag using the packaging material, which has high strength and excellent linear tearability.

  Conventionally, as a packaging material used for packaging an article, a material in which paper or nonwoven fabric is used as a base material and a polyethylene film is laminated on the back surface thereof is known. And a packaging bag is obtained by enclosing a to-be-packaged object with a polyethylene film inside, and heat-sealing the polyethylene films which oppose around the to-be-packaged object. However, the paper-based packaging material has low strength, and the tearing direction is not constant due to the arrangement structure of the paper fibers. Fluffing may occur. Non-woven fabric-based packaging materials are also generally used as spunbond nonwoven fabric, and the fibers are arranged in random directions, so that strength and linear tearability are still insufficient. It is.

Patent Document 1 includes a mixture of 100 parts by weight of linear low density polyethylene and 5 to 40 parts by weight of low density polyethylene as a packaging material that can be easily torn by hand and has excellent heat sealability. The packaging material which laminated | stacked the polyethylene-type film on the base material layer which consists of a thermoplastic resin film, a metal vapor deposition film, etc. is disclosed.
Japanese Patent Laid-Open No. 2002-287962

  However, in the packaging material disclosed in Patent Document 1, although the strength, tearability, and heat sealability are superior to those using paper or a spunbonded nonwoven fabric as the base material, the weight of the packaged item is large. Sometimes the required strength could not be obtained. It is important that the packaging bag does not tear when dropped from a certain height. Although what was disclosed by patent document 1 has the intensity | strength which does not become a problem in particular if the weight of a packaged thing is about several hundred g, when the weight of a packaged article reaches several to several dozen kg. The required strength is not always obtained. In the worst case, the packaging bag is torn due to an external impact such as dropping, and the packaged item flows out.

  In view of the above, an object of the present invention is to provide a packaging material and a packaging bag that have good linear tearability and have sufficient strength to withstand even when heavy objects are packaged.

  In order to achieve the above object, the packaging material of the present invention has a surface layer and a reinforcing layer laminated on one surface of the surface layer. The reinforcing layer is made of a thermoplastic resin and stretched in one direction and is formed by stretching the stretched bodies having different shear strengths so that the stretch directions are orthogonal to each other, and the laminate is laminated on the network structure. And a laminate layer made of a thermoplastic resin.

  In the packaging material described above, by making the thickness of the stretched body having the lower shear strength smaller than the thickness of the stretched body having the higher shear strength, the shear strength of each stretched body can be made different. The network structure can be made from a raw material in which a layer made of a second thermoplastic resin having a melting point lower than that of the first thermoplastic resin is laminated on both surfaces of the layer made of the first thermoplastic resin. Specific embodiments of the network structure include (1) a nonwoven fabric obtained by laminating uniaxially stretched network films so that the stretching directions are perpendicular to each other, and (2) a woven fabric obtained by weaving uniaxially stretched tapes so that the stretching directions are perpendicular to each other. Examples thereof include a cloth, (3) a nonwoven fabric obtained by laminating uniaxially stretched tapes so that the stretching directions are orthogonal, and (4) and a laminate in which uniaxially stretched network films and uniaxially stretched tapes are laminated so that the stretching directions are orthogonal. .

  Moreover, in the packaging material of this invention, it is preferable that the heat seal layer which consists of a thermoplastic resin is provided in the surface on the opposite side to the surface where the surface layer of the reinforcement layer was laminated | stacked. In this case, considering recyclability, it is preferable that the surface layer, the reinforcing layer, and the heat seal layer are made of polyethylene resin.

  The packaging bag of this invention is a packaging bag using the packaging material of the said invention, Comprising: The notch is formed in the edge part in the extending | stretching direction of the extending | stretching body with higher shear strength, It is characterized by the above-mentioned.

  In the present specification, the “longitudinal direction” of the film, the nonwoven fabric, and the packaging material means a machine direction, that is, a feeding direction in manufacturing these, and the “lateral direction” is a direction perpendicular to the longitudinal direction. That is, it means these width directions when manufacturing films, nonwoven fabrics, and packaging materials.

  According to the packaging material of the present invention, since it has a reinforcing layer using a network structure in which stretched bodies formed by stretching are combined so that the stretching directions are orthogonal to each other, the tensile strength necessary for the packaging material is ensured. Even when heavy objects are packaged, the packaging material can be prevented from being torn. Moreover, since each stretched body has a different shear strength and is restrained by the laminate layer, the packaging material can be easily and linearly torn along the stretched body having the higher tip strength.

  In addition, according to the packaging bag of the present invention, the packaging material of the present invention can be easily torn linearly from the notch by forming a cut at an appropriate place according to the shear strength of the stretched body. Therefore, it is possible to prevent the packaged items from being scattered or spilled when the packaging bag is opened. Further, since the packaging material has a high tensile strength, the packaging bag is not easily broken even when a heavy object is packaged.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a packaging material according to an embodiment of the present invention. The packaging material 1 of the present embodiment has a reinforcing layer 3, a surface layer 2 laminated on one surface of the reinforcing layer 3, and a back surface layer 4 laminated on the other surface of the reinforcing layer 3. The surface layer 2 imparts designability to the packaging material 1 and has a predetermined function required for the packaging material 1 in accordance with an object to be packaged. The reinforcing layer 3 bears the strength of the packaging material 1. The back layer 4 is an inner layer when manufacturing the packaging bag, and functions as a heat seal layer when the packaging bag is manufactured by heat sealing.

  Hereinafter, each of these layers will be described.

(1) Surface layer The surface layer 2 is a layer that appears on the surface of the packaging bag when it is used as a packaging bag, and displays information such as the design of the packaging bag, product name, manufacturer, seller, and content. Is applied to the surface layer 2 by printing or the like. Therefore, in order to obtain a good appearance and printability, the surface layer 2 is preferably smooth. For this purpose, a film can be used for the surface layer 2. In addition, when displaying information by sticking a label, it is not necessary to print.

  Further, the surface layer 2 can have a function required for the packaging bag in accordance with the type of the object to be packaged to be packaged in the packaging bag. The function is, for example, a moisture-proof function if the package does not like moisture ingress, and prevents the package from being affected by static electricity such as when the package is an electronic component or electronic device. It is an antistatic function when necessary.

  The surface layer 2 does not need to be a single layer, and can be composed of a plurality of layers if necessary to provide the above-described functions. Below, the structural example of the surface layer 2 applicable to this invention is shown.

  In consideration of recyclability, polyethylene (low / medium / high density polyethylene) can be used for the surface layer 2. In this case, however, the other layers (reinforcing layer 3 and back layer 4) must also be made of a polyethylene resin. If the surface layer 2 is composed of a polyethylene film, the back surface (laminated surface with the reinforcing layer 3) can be printed in advance. The print information is visible through the polyethylene film.

  When it is set as the packaging bag which needs moisture-proof property, the surface layer 2 can be comprised with the polyethylene terephthalate film (PET film) which vapor-deposited aluminum, aluminum foil, etc. Further, when printing is necessary, for example, a surface layer 2 is obtained by laminating a film on which the back surface is printed on the surface opposite to the surface on which the PET film is laminated with the reinforcing layer 3 by a dry lamination method or the like. Can be used. Examples of this film include nylon films and biaxially stretched polypropylene films.

(2) Reinforcing layer The reinforcing layer 3 imparts a linear tearing property while giving the packaging material 1 the necessary strength.

  A schematic cross-sectional view of the reinforcing layer 3 is shown in FIG. As shown in FIG. 2, the reinforcing layer 3 is obtained by forming laminated layers 35 on both surfaces of a split fiber nonwoven fabric 32 obtained by laminating two uniaxially stretched split fiber films 31 by thermal fusion.

  As shown in FIG. 3B, the uniaxially stretched split fiber film 31 is a second thermoplastic resin having a melting point lower than that of the first thermoplastic resin on both surfaces of the layer 31a made of the first thermoplastic resin. 3b. As shown in FIG. 3A, a plurality of trunk fibers 33 that extend in parallel to each other, and the trunk fibers adjacent to each other that extend across the trunk fibers 33. It is comprised with the branch fiber 34 which connects 33 mutually. The branch fibers 34 are thinner than the trunk fibers 33, and the mechanical strength of the uniaxially stretched split fiber film 31 is mainly provided by the trunk fibers 33.

  The thickness of the layer 31b made of the second thermoplastic resin is 50% or less, desirably 40% or less, of the total thickness of the uniaxially stretched split fiber film 31. In order to satisfy various physical properties such as adhesive strength at the time of thermal fusion of the two uniaxially stretched split fiber films 31, the thickness of the layer 31b made of the second thermoplastic resin may be 5 μm or more, preferably Is selected from the range of 10 to 100 μm.

  As a manufacturing method of the uniaxial stretch split fiber film 31, the method as shown below is mentioned, for example.

  First, an original film having a three-layer structure in which a layer 31b made of a second thermoplastic resin is laminated on both surfaces of a layer 31a made of a first thermoplastic resin by extrusion molding such as a multilayer inflation method or a multilayer T-die method. Manufacturing. Next, as shown in FIG. 4, the raw film 30 is split in a vertical direction (L direction shown in FIG. 4) in a zigzag manner using a splitter (splitting treatment) or slitted with a hot blade. Is applied to form a large number of parallel slits 30a, which are further stretched in the longitudinal direction to widen them. Thereby, the uniaxially stretched split fiber film 31 in which the trunk fibers 33 are arranged substantially in the longitudinal direction as shown in FIG. 3 is obtained.

  The draw ratio (orientation ratio) is preferably 1.1 to 15 times. If the draw ratio is less than 1.1 times, the mechanical strength when used as the reinforcing layer 3 may not be sufficient. On the other hand, when the draw ratio exceeds 15 times, it is difficult to draw by a usual method, and problems such as the need for an expensive apparatus arise. Stretching is preferably performed in multiple stages in order to prevent stretching unevenness.

  Finally, the uniaxially stretched split fiber film 31 obtained as described above is overlapped so that the stretching directions are orthogonal to each other, and this is heated and fused, as shown in FIG. A split fiber nonwoven fabric 32 in which the trunk fibers 33 of the uniaxially stretched split fiber film 31 are orthogonal is obtained. At the time of heat fusion, the superposed uniaxially stretched split fiber film 31 is supplied between a pair of opposed heating cylinders and fixed so as not to shrink in the width direction, and the first thermoplastic resin is used. In order not to lose the stretching effect of the layer 31a made of, heat fusion is performed at a temperature not higher than the melting point of the first thermoplastic resin and not lower than the melting point of the second thermoplastic resin.

  Here, in the present invention, the uniaxially stretched split fiber films 31 have different tear strengths in the direction perpendicular to the arrangement direction of the trunk fibers 33, and the trunk fibers 33 are arranged along the intended tear direction. The uniaxially stretched split fiber film 31 is smaller in tear strength than the other. For this reason, in this embodiment, the thickness (width) of the trunk fiber 33 which is a fiber mainly constituting the uniaxially stretched split fiber film 31 for reducing the tear strength is compared with that of the other uniaxially stretched split fiber film 31. It is thin.

  As shown in FIG. 2, a resin laminate layer 35 is formed on both surfaces of the split fiber nonwoven fabric 32 described above. In FIG. 2, the boundary between the laminate layer 35 and the split fiber nonwoven fabric 32 is clearly shown, but actually, the laminate layer 35 is formed so that the resin of the laminate layer 35 constitutes the split fiber nonwoven fabric 32. It penetrates between the fibers of the stretched split fiber film 31 or penetrates between the fibers and is joined to the opposite laminate layer 35.

  As the resin used for the laminate layer 35, polyethylene (low / medium / high density polyethylene), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), or the like can be used. For the formation of the laminate layer 35, for example, an extrusion lamination method such as a T-die method can be used. Moreover, a laminated layer can also be formed by laminating the film on the split fiber nonwoven fabric 32 in a softened state.

(3) Back surface layer Referring back to FIG. 1, the back surface layer 4 functions as a heat seal layer when making a packaging bag from the packaging material 1 as described above. Therefore, when making a packaging bag by adhesion | attachment or sewing machine sewing, the back surface layer 4 does not necessarily need to be provided.

  As the resin constituting the back layer 4, any resin can be used as long as it is a resin suitable for heat sealing, and a polyolefin resin is particularly preferably used. Examples of polyolefin resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer, high-pressure low-density branched polyethylene, polypropylene, propylene and other olefins. A copolymer or a mixture of these polyolefins can be used, and among them, a polyethylene resin is preferable from the viewpoint of heat sealability.

  As mentioned above, although the surface layer 2, the reinforcement layer 3, and the back surface layer 4 which comprise the packaging material 1 were demonstrated, the packaging material 1 of this embodiment uses the reinforcement layer 3 which has the split fiber nonwoven fabric 32 as mentioned above. Yes. Since the split fiber nonwoven fabric 32 is configured by laminating two uniaxially stretched split fiber films 31 such that the stretching directions thereof are orthogonal to each other, the packaging material 1 in the directions orthogonal to each other (for example, the vertical direction and the horizontal direction). Even when it is used for packaging heavy objects reaching several kg to several tens kg, it is not easily broken by an impact such as dropping.

  Moreover, each uniaxially stretched split fiber film 31 has different thicknesses of the trunk fibers 33 and different shear strengths. Therefore, when the packaging material 1 is torn along the trunk fiber 33 having the higher shear strength, the trunk fiber 33 having the lower shear strength is individually broken, but the trunk fiber 33 having the higher shear strength is Without breaking, the packaging material 1 is torn linearly along the trunk fiber 33 having the higher shear strength. On the other hand, when trying to tear the packaging material 1 along the trunk fiber 33 having a lower shear strength, a greater force is required than in the above case.

  Here, since the laminate layers 35 are formed on both surfaces of the split fiber nonwoven fabric 32, the fibers (the trunk fibers 33 and the branch fibers 34) constituting the uniaxially stretched split fiber film 31 are more firmly restrained by the laminate layer 35. . As a result, the force applied when tearing the packaging material 1 acts on the trunk fiber 33 to be broken, and the tearability of the packaging material 1 is improved. If the binding force of the fibers constituting the uniaxially stretched split fiber film 31 is small, the uniaxially stretched split fiber film 31 is peeled off and the trunk fiber 33 is not easily broken when a tearing force is applied to the packaging material 1. Tearability is not obtained.

  Moreover, since each layer of the surface layer 2, the reinforcement layer 3, and the back surface layer 4 which comprise the packaging material 1 can be comprised with a thermoplastic resin, if these are comprised with the same kind of resin, recycling is also easy. . In consideration of recycling, it is preferable to use a polyethylene resin as the resin.

  In addition, as shown in FIG. 5, when the split fiber nonwoven fabric 32 is comprised using the uniaxially stretched split fiber film 31 of the same form, an orthogonal laminating machine is used for the heat fusion of the uniaxial stretch split fiber film 31. Used. At the time of heat fusion by this orthogonal laminating machine, one uniaxially stretched split fiber film 31 is supplied to the orthogonal laminator as it is, but the other is cut into a sheet having the same length as the width of the uniaxially stretched split fiber film 31. And is supplied from a direction perpendicular to one of the uniaxially stretched split fiber films 31. Therefore, in the form shown in FIG. 5, there is a seam of the other uniaxially stretched split fiber film 31 at regular intervals.

  As mentioned above, although the example which comprised the network structure using the uniaxially stretched split fiber film 31 as a network film in the present invention was shown, when the existence of the above-mentioned joint which arises in this case is not preferred, 6 is preferably laminated with the uniaxially stretched split fiber film 31 shown in FIG. 3 to form a split fiber nonwoven fabric.

  The uniaxially stretched slit film 36 shown in FIG. 6 can be made from an original fabric film having the same structure as that used to manufacture the uniaxially stretched split fiber film 31 shown in FIG. That is, as shown in FIG. 6, the uniaxially stretched slit film 36 includes a layer 36 a made of the first thermoplastic resin, and a second melting point lower than that of the first thermoplastic resin laminated on both surfaces thereof. And a layer 36b made of a thermoplastic resin. Then, the raw film is split in the horizontal direction (arrow T direction shown in FIG. 6) in a zigzag manner, or stretched in the horizontal direction and stretched in the vertical direction so that the fibers are almost The uniaxially stretched slit film 36 arranged in the transverse direction is obtained. Thus, by laminating the uniaxially stretched split fiber film 31 stretched in the longitudinal direction and the uniaxially stretched slit film 36 stretched in the lateral direction, a seamless split fiber nonwoven fabric can be obtained. In addition, although a seam will exist like what was shown in FIG. 3, the split fiber nonwoven fabric is comprised by superimposing two uniaxially stretched slit films 36 shown in FIG. 6 so that the orientation axes are orthogonal to each other. You can also

  Examples of the resin constituting the uniaxially stretched split fiber film 31 and the uniaxially stretched slit film 36 include polyolefins such as polyethylene and polypropylene and copolymers thereof, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and copolymers thereof, Examples thereof include polyamides such as nylon 6 and nylon 66 and copolymers thereof, polymers and copolymers of polyvinyl chloride, methacrylic acid or derivatives thereof, polystyrene, polysulfone, polytetrachloroethylene polycarbonate, polyurethane and the like. Among these, polyolefins having good splitting properties and polymers thereof, polyesters and polymers thereof are preferable. 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.

  As described above, the example in which the split fiber nonwoven fabric 32 is used for the reinforcing layer 3 has been described. In addition to this, the reinforcing layer 3 includes a nonwoven fabric 37 or a woven fabric made of a uniaxially stretched multilayer tape 39 as shown in FIGS. A cloth 38 or the like can also be used. The nonwoven fabric 37 and the woven fabric 38 are 1.1 to 15 times, preferably 3 to 10 times, the same raw film as that used for producing the uniaxially stretched split fiber film 31 shown in FIG. The uniaxially stretched multilayer tape 39 is uniaxially stretched and then cut along the stretch direction. The raw film may be cut before stretching. The nonwoven fabric 37 shown in FIG. 7 is obtained by arranging the uniaxially stretched multilayer tapes 39 in parallel at regular intervals and laminating them vertically and horizontally. The woven fabric 38 shown in FIG. 8 is obtained by weaving the uniaxially stretched multilayer tape 39 vertically and horizontally. In the nonwoven fabric 37 and the woven fabric 38, the uniaxially stretched multilayer tape 39 has different tear strengths in the longitudinal direction and the transverse direction, and the uniaxially stretched multilayer tape 39 arranged in a direction perpendicular to the intended tear direction is Compared with the other uniaxially stretched multilayer tape 39, the width is narrow and the shear strength is small.

  And the nonwoven fabrics 37 and 38 comprise the laminated layer 35 on both surfaces similarly to the split fiber nonwoven fabric 32 shown in FIG.

  In addition to the above-described uniaxially stretched split fiber film, split fiber nonwoven fabric composed of uniaxially stretched slits, woven fabric composed of uniaxially stretched multilayer tape, and nonwoven fabric, the network structure constituting the reinforcing layer 3 is uniaxially stretched and fibers. A laminate in which a film and a uniaxially stretched multilayer tape are laminated so that the stretching directions are orthogonal, and further, a woven fabric or a nonwoven fabric in which filaments spun and stretched from a thermoplastic resin are combined so that the stretching directions are orthogonal Also good.

  In order to manufacture a packaging bag from the packaging material 1 shown in FIG. 1, at least a step of enclosing an article to be packaged with the packaging material 1 and at least one step of heat-sealing the packaging material 1 are necessary. In the process of surrounding the packaged object, the packaged object is surrounded with the back surface layer 4 as the inner side. Moreover, the process of heat-sealing the packaging material 1 may be performed separately before and after the process of surrounding the packaged object, depending on the type of packaged object and the form of the packaging bag.

  For example, when the article to be packaged is a solid substance, the article to be packaged is placed on the packaging material 1 with the back surface layer 4 facing the upper surface, and then the object to be packaged is surrounded by an appropriate method so that the back layer 4 By facing each other and heat-sealing the opposite back surface layers 4 around the packaged object, a packaging bag in which the packaged object is enclosed can be manufactured. In addition, when the packaged material is a powder, granule, fluid, or the like that does not take a certain shape in the packaging bag, first, heat the appropriate portion of the packaging material 1 with the back layer 4 inside. By sealing, a bag having an open upper end is formed. Next, the packaging material is put into the bag from the opened upper end, and finally, the packaging bag in which the packaging material is enclosed is sealed by heat-sealing the upper end portion of the bag in which the packaging material is placed. Can be manufactured. This method is applicable even when the packaged item is a solid.

  There are various forms of packaging bags, an example of which is shown in FIG. The packaging bag 40 shown in FIG. 9 is a so-called four-side seal type, and is manufactured by stacking two packaging materials 1 between the objects to be packaged, and heat-sealing the four sides of the peripheral portion. Each has a vertical seal portion 40a along the vertical direction and a horizontal seal portion 40b along the horizontal direction at the upper and lower ends.

  The packaging material 1 used for the packaging bag 40 has the reinforcing layer 3 in which the shear strengths of the two uniaxially stretched split fiber films 31 (see FIG. 5) are different from each other so that the packaging material 1 is easier to tear in the lateral direction than in the longitudinal direction. (See FIG. 1). Specifically, the stretching direction of each uniaxially stretched split fiber film 31 in FIG. 5, that is, the arrangement direction of the trunk fibers 33 is the longitudinal direction and the transverse direction, respectively, and the thickness of the trunk fibers 33 arranged in the longitudinal direction is the transverse direction. By making it thinner than the thickness of the arranged trunk fibers 33, the shear strength of the one-way stretched split fiber film 31 having the trunk fibers 33 arranged in the longitudinal direction is made larger than the shear strength of the other one-way stretched split fiber film 31. The packaging material 1 is produced at a low level.

  Accordingly, the packaging bag 40 has a seal portion at the end in the stretching direction of the uniaxially stretched split fiber film 31 having higher shear strength, in other words, the uniaxially stretched split fiber film 31 having lower shear strength. A cut 41 is formed in a part of the vertical seal portion 40a which is a seal portion along the extending direction.

  In order to open the packaging bag 40, the upper portion and the lower portion of the cut 41 are held by hand, and the upper portion is pulled in the lateral direction. As a result, the packaging material 1 is torn laterally from the cuts 41 and the packaging bag 40 is opened. Since the notch 41 is formed in the packaging bag 40, stress concentrates at the tip of the notch 41 at the start of tearing, and the packaging material 1 can be easily torn using the notch 41 as a guide. Moreover, as described above, since the packaging material 1 is torn linearly, the packaged material is not spilled or scattered even if the packaged material is powder or fluid.

  The shape of the notch 41 may be a wedge shape as shown in FIG. 9 as long as it can trigger tearing, or may be formed simply as a cut, or any shape.

  FIG. 9 shows a four-side-seal type packaging bag 40, but other various types of packaging bags such as a three-side-seal type packaging bag, a back-sticking type packaging bag, and a standing-type packaging bag can be used. The present invention is also applicable. By the way, the three-side-seal type packaging bag can be manufactured by folding the packaging material in half at the center in the width direction and heat-sealing the three sides of the peripheral portion. The back-packed packaging bag first overlaps the side edges of the packaging material with the inner surfaces facing each other, and heats the overlapped portion along the side edge of the packaging material to form a cylinder, Next, the open end of the cylindrical packaging material can be manufactured by heat-sealing over the entire width of the packaging material. In the back-wrapping packaging, the heat seal part for making the packaging material into a cylindrical shape is located on the back surface (preferably the central part in the width direction) of the packaging bag. Further, back-packed packaging is roughly classified into a flat bag shape and a gusset bag in which both lateral ends are folded inward, and the present invention can be applied to any of these. In addition, the standing type packaging bag heat-seals the entire circumference of the packaging bag, but can be manufactured by folding this portion inward when the portion corresponding to the bottom of the packaging bag is heat-sealed.

  In the three-side seal type, four-side seal type and standing type packaging bags, the heat seal part (vertical seal part and horizontal seal part) is located at the end of the packaging bag, so that the packaging material is easily torn in the lateral direction. In this case, a cut is formed in the corresponding heat seal portion (that is, the vertical seal portion when tearing in the horizontal direction and the horizontal seal portion when tearing in the vertical direction). By doing so, the packaging bag can be torn laterally or longitudinally from its end.

  On the other hand, in the case of back-wrapped packaging, the situation is different from that of a three-way seal. In FIG. 10, the perspective view which looked at the typical back-sticking type packaging bag by this invention from the back side is shown. The packaging bag 50 shown in FIG. 10 is formed so as to be easily torn in the lateral direction compared to the longitudinal direction from the packaging material in which the surface layer, the reinforcing layer, and the back layer of the present invention are laminated. In the packaging bag 50, a vertical seal portion 50a is formed at the central portion in the horizontal direction, and horizontal seal portions 50b are formed at both ends in the vertical direction. The notch 51 is formed not at the end portion of the packaging bag 50 but at a position of the vertical seal portion 50a that does not overlap the horizontal seal portion 50b. Thereby, by tearing the packaging material at the portion of the notch 51, the packaging bag 50 is torn linearly from the center in the width direction and opened. When the packaging material is formed so as to be easily torn in the vertical direction, a cut can be formed in the horizontal seal portion 50b so as to be torn in the vertical direction.

  FIG. 11 shows another example of the back-attached packaging bag according to the present invention. The packaging bag 60 shown in FIG. 11 is also made of a packaging material formed so as to be easily torn in the horizontal direction compared to the vertical direction, similar to that shown in FIG. A vertical seal 60a is formed on each side, and horizontal seal portions 60b and 60c are formed on both ends in the vertical direction. However, in this example, one horizontal seal portion 60c is formed in a boat bottom type so that the seal width becomes large at one end portion or both end portions and extends in the vertical direction. And the notch 61 is formed in the extended part of this horizontal seal | sticker part 60c. Thus, by making the horizontal seal part 60c into a boat bottom type, even in a back-paste type packaging bag, it can be opened from the end of the packaging bag in the same manner as a three-sided seal type or four-sided seal type packaging bag. .

  The packaging bag described above has been described by taking the case of using a packaging material having a back layer (heat seal layer) as an example, but the same applies to a packaging material in which a back layer is not provided. For example, when a packaging bag is formed by an adhesive instead of heat sealing, the adhesive portion, which is an area bonded with the adhesive, is considered to be replaced with the heat sealing portion described above, and a cut is formed at an appropriate portion of the adhesive portion. In the case of sewing, the outer region is replaced with the heat seal portion described above with the perforation as a boundary, and cuts are formed at appropriate locations in the outer region of the perforation.

  Hereinafter, specific examples of the present invention will be described together with comparative examples.

(Example)
A nylon film printed on the back surface and a PET film deposited with aluminum were laminated by a dry lamination method to produce a surface layer. As the reinforcing layer, uniaxially stretched split fiber films produced in the pattern shown in FIG. 3 are laminated so that the stretching directions are orthogonal to form a split fiber nonwoven fabric as shown in FIG. A laminate layer of 20 μm thick was used. The uniaxially stretched split fiber film is subjected to split treatment on a raw film in which a layer made of low-density polyethylene having a thickness of 15 μm is laminated on both sides of a layer made of high-density polyethylene having a thickness of 65 μm. It was produced by stretching twice and widening. The total thickness of the uniaxially stretched split fiber film was 35 μm. In addition, the thickness of the stem fiber of the uniaxially stretched split fiber film is 0.565 mm and 0.433 mm, respectively, the thicker trunk fibers are arranged in the horizontal direction, and the thinner trunk fibers are arranged in the vertical direction. Thus, by laminating uniaxially stretched split fiber films, a split fiber nonwoven fabric that is easily torn in the transverse direction as compared to the longitudinal direction was obtained. For reference, the thickness of the branch fiber was 0.141 mm for the uniaxially stretched split fiber film with the thicker trunk fiber and 0.144 mm for the uniaxially stretched split fiber film with the thinner stem fiber.

  Then, a surface layer was laminated on one side of the reinforcing layer, and a back layer made of linear low density polyethylene was laminated as a heat seal layer on the opposite side to obtain a packaging material.

  Using the obtained packaging material, a packaging bag having outer dimensions of a longitudinal length of 660 mm and a lateral length of 470 mm so that the longitudinal direction of the packaging material becomes the longitudinal direction of the broadcast bag as it is by a filling and packaging machine. Was made. The form of the packaging bag was a four-side sealed package. In the packaging bag, 25 kg of asphalt was enclosed. Further, a wedge-shaped cut having a length of 10 mm was formed in the vertical seal portion of the packaging bag.

(Comparative example)
A packaging material was prepared in the same manner as in the example except that paper having a basis weight of 80 g / m ² was used instead of the reinforcing layer in the example, and the packaging bag similar to the example was prepared using the packaging material. Produced.

(Evaluation)
About an Example and a comparative example, evaluation of the strength by a bag drop test and evaluation about tearability were performed.

  In the bag drop test, each of the three directions of (a) the direction falling from the horizontal side, (b) the direction falling from the vertical side, and (c) the direction falling from the corner is 10 m from the height of 1 m. Practical strength was evaluated by dropping the bags one by one and the number of bags that had broken bags. If no bag breakage occurs, repeat the same test until the bag breakage occurs. Normally, in this type of bag drop test, if no bag breakage occurs after two drops, it is judged as acceptable. Table 1 shows the results of the bag drop test. In Table 1, the test results are expressed as (number of broken bags) / (number of dropped bags).

表１から明らかなように、実施例ではいずれの方向についても２回の落下で破袋は生じなかった。また、３回目の落下においても破袋が生じたのは一部の包装袋のみであった。このことから、実施例の包装袋は十分な実用強度を有しているといえる。一方、比較例では、いずれの方向についても１回目の落下で全数に破袋が生じた。

As is clear from Table 1, in the example, no bag breakage was caused by two drops in any direction. In addition, only a part of the packaging bags were broken even in the third drop. From this, it can be said that the packaging bag of an Example has sufficient practical strength. On the other hand, in the comparative example, in all directions, bag breakage occurred in the total number by the first drop.

  In the evaluation of tearability, the evaluation was made based on whether or not the packaging bag could be torn linearly when it was torn at the cut portion. In the example, due to the structure of the reinforcing layer, it could be torn linearly in the lateral direction. On the other hand, in the comparative example, the tearing direction was not stable and could not be torn linearly.

  For reference, the tensile strength in the machine direction and transverse direction of the split fiber nonwoven fabric used in the examples was measured. The tensile strength was measured by taking a sample having a length of 200 mm and a width of 50 mm in the longitudinal direction and the transverse direction, respectively, from the obtained split fiber nonwoven fabric, and taking the sample at a constant speed with a chuck-to-chuck distance of 100 mm and a pulling speed of 200 mm / min. The tensile load (N / 50 mm) was taken as the maximum load until the sample was broken by a tensile tensile tester. The tensile strength was 145 N / 50 mm in the vertical direction and 285 N / 50 mm in the horizontal direction. As a measure of the tensile strength per fiber (stem fiber), the number of stem fibers in the sample was counted, and the single fiber strength was determined by dividing the measured tensile strength value by the number of fibers. The direction was 5N and the horizontal direction was 9N.

It is typical sectional drawing of the packaging material by one Embodiment of this invention. FIG. 2 is a schematic cross-sectional view of a reinforcing layer shown in FIG. 1. It is a fragmentary perspective view of the uniaxially stretched split fiber film shown in FIG. It is a fragmentary perspective view in the state where the slit was put of the original fabric film used for manufacturing the uniaxially stretched split fiber film shown in FIG. It is a top view of the split fiber nonwoven fabric shown in FIG. It is a fragmentary perspective view of the uniaxially stretched split fiber film extended | stretched to the horizontal direction applicable to this invention. It is a top view of the nonwoven fabric which is another example of the network structure applicable to this invention. It is a top view of the woven fabric which is another example of the network structure applicable to this invention. FIG. 2 is a front view of an example of a four-side sealed packaging bag manufactured using the packaging material shown in FIG. 1. It is a perspective view of an example of the back-sticking type packaging bag by this invention. It is a front view of the other example of the back bonding type packaging bag by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Packaging material 2 Surface layer 3 Reinforcement layer 4 Back surface layer 31 Uniaxially stretched split fiber film 31a, 36a Layer made of the first thermoplastic resin 31b, 36b Layer made of the second thermoplastic resin 32 Split fiber nonwoven fabric 33 Trunk fiber 34 Branch fiber 35 Laminate layer 36 Uniaxially stretched slit film 37 Nonwoven fabric 38 Woven fabric 39 Uniaxially stretched multilayer tape 40, 50, 60 Packaging bag 40a, 50a, 60a Vertical seal portion 40b, 50b, 60b, 60c Horizontal seal portion 41, 51, 61 Notch

Claims (5)

A surface layer, and a reinforcing layer laminated on one side of the surface layer,
The reinforcing layer is made of a thermoplastic resin and stretched in one direction, and is formed by stretching the stretched bodies having different shear strengths so that the stretch directions are orthogonal to each other, and the laminate is laminated on the mesh-like structure. A packaging material comprising a laminate layer made of a thermoplastic resin.   The packaging material according to claim 1, wherein a thickness of the stretched body having a lower shear strength is thinner than a thickness of the stretched body having a higher shear strength.   The network structure is made of a raw material in which a layer made of a second thermoplastic resin having a melting point lower than that of the first thermoplastic resin is laminated on both surfaces of the layer made of the first thermoplastic resin. (1) A nonwoven fabric obtained by laminating uniaxially stretched network films so that the stretching directions are perpendicular to each other, (2) a woven fabric obtained by weaving uniaxially stretched tapes so that the stretching directions are perpendicular, and (3) a uniaxially stretched tape in the stretching direction. The packaging according to claim 1 or 2, which is any one of a non-woven fabric obtained by laminating so as to be orthogonal to each other, (4), and a laminate obtained by laminating a uniaxially stretched network film and a uniaxially stretched tape so that the stretching directions are orthogonal material.   The packaging material according to any one of claims 1 to 3, wherein a heat seal layer made of a thermoplastic resin is provided on a surface opposite to the surface on which the surface layer of the reinforcing layer is laminated. A packaging bag using the packaging material according to any one of claims 1 to 4,
A packaging bag, wherein an incision is formed in an end portion in the stretching direction of the stretched body having higher shear strength.

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