packaging bags

Abstract

The present invention provides a packaging bag, in which a bottom component folded in half using a fold line is clamped between a pair of main body components, a main body sealing portion is formed at a position above the packaging bag relative to the fold line, the inner surfaces of the pair of main body components being joined to each other along the left and right peripheral portions of the packaging bag, and a bottom sealing portion is formed at a position below the packaging bag relative to the fold line, the inner surface of the bottom component being joined to the inner surface of the main body component, and contents can be stored in an unsealed portion surrounded by the main body sealing portion and the bottom sealing portion, the main body component and the bottom component being formed by a film whose resin layer is composed only of a polyethylene resin, and the boundary between the bottom sealing portion and the unsealed portion is convex toward the upper side of the packaging bag near the contact with the main body sealing portion.

Description

Technical Field

[0001] The present invention relates to a packaging bag.

[0002] This application claims priority based on Japanese Patent Application No. 2020-182473 filed in Japan on October 30, 2020, and incorporates the contents thereof herein. Background Art

[0003] Patent Document 1 describes a packaging bag having a structure in which a mountain-folded bottom member is sandwiched between the lower portions of a pair of opposing main body members. This packaging bag is formed into a self-standing packaging bag (stand-up bag) by combining the pair of main body members and the mountain-folded bottom member and unfolding the four overlapping lower portions.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-129690 Summary of the Invention

[0007] Technical issues

[0008] In conventional packaging bags, the composite film used for the main body and bottom parts has a heat-adhesive resin (sealant) layer, such as polyethylene (PE), laminated on the inner surface, and a base material, such as polyethylene terephthalate (PET), which has higher heat resistance than the sealant, laminated on the outer surface. When the main body parts are thermally bonded together, or when the main body and bottom parts are thermally bonded, the sealant melts, bonding the inner surfaces of the composite film.

[0009] However, packaging bags containing different types of resins have a problem in that they are difficult to recycle as plastic container packaging.

[0010] In recent years, the use of single-material container packaging made of a single resin has been advocated to facilitate recycling. However, research by the present inventors has revealed that laminating a sealant with the same resin as the base material can reduce the strength of the hot zone of the adhesive composite film, particularly reducing the durability of the package when dropped.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a self-supporting packaging bag (standing bag) having excellent durability even when the packaging bag is made of a single material.

[0012] Technical Solution

[0013] In order to solve the above-mentioned problem, the present invention provides a packaging bag, wherein the packaging bag sandwiches a bottom component folded in half using a fold line between a pair of main body components, and a main body sealing portion is formed at a position above the fold line of the packaging bag, in which the inner surfaces of the pair of main body components are joined to each other along the left and right peripheral portions of the packaging bag, and a bottom sealing portion is formed at a position below the fold line of the packaging bag, in which the inner surface of the bottom component is joined to the inner surface of the main body component, so that contents can be stored in an unsealed portion surrounded by the main body sealing portion and the bottom sealing portion, and the main body component and the bottom component are formed of a film whose resin layer is composed only of a polyethylene resin, and the boundary between the bottom sealing portion and the unsealed portion is convex toward the upper side of the packaging bag near the contact with the main body sealing portion.

[0014] The film is a laminated film having a sealant layer laminated on the inner surface of the film and a substrate layer laminated on the outside of the sealant layer in the thickness direction of the film. The sealant layer can be formed of an unstretched polyethylene resin, and the substrate layer can be formed of a stretched polyethylene resin.

[0015] A boundary portion between the bottom sealed portion and the unsealed portion may be convex toward the bottom of the packaging bag at a center portion in the left-right direction of the packaging bag.

[0016] The outer surfaces of the bottom members may be joined to each other at left and right peripheral portions of the packaging bag.

[0017] Effects of the Invention

[0018] According to the present invention, even in a self-supporting packaging bag (standing bag) made of a single material, it is possible to provide a packaging bag having excellent durability at the joint between the main body member and the bottom member. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a front view showing the lower portion of the packaging bag of the present invention.

[0020] Figure 2 This is a perspective view showing a state where the packaging bag of the present invention is expanded.

[0021] Explanation of symbols

[0022] L…extension line, P…intersection point, 1…main body sealing portion, 2…bottom sealing portion, 2a…boundary portion, 2b…center portion of the bottom sealing portion, 2c…side end portion of the bottom sealing portion, 2d…bent portion, 3…main body component, 4…bottom component, 4a…fold line, 4b…lower portion of the bottom component, 4c…side portion of the bottom component, 5…unsealed portion, 6…filling port, 7…pour port, 7a…flow path, 7b…flow path forming seal portion, 7c…flow path closing seal portion, 10…packaging bag, 11…left and right peripheral portions, 12…lower corner portion. DETAILED DESCRIPTION

[0023] Hereinafter, the present invention will be described based on preferred embodiments with reference to the accompanying drawings.

[0024] Figure 1 The lower portion of the packaging bag 10 according to the embodiment is shown. Figure 2 The packaging bag 10 of the embodiment is shown in a state where the lower portion thereof is inflated. The packaging bag 10 is formed by a bottom member 4 folded in two along a fold line 4a and a pair of main body members 3 arranged so as to sandwich the bottom member 4 therebetween.

[0025] like Figure 1 As shown, in the description of the embodiment, the vertical direction of the packaging bag 10 is such that the side of the packaging bag 10 having the bottom member 4 is the bottom side. The top view in the description of the embodiment corresponds to the state of the packaging bag 10 being folded substantially flat and viewed from a direction perpendicular to the paper surface. The main body member 3 is substantially along the vertical direction when viewed from the top. Figure 1 The top side of the packaging bag 10 is the side opposite to the side of the packaging bag 10 having the bottom member 4. When viewed from above, the vertical direction of the packaging bag 10 is approximately perpendicular to the direction in which the fold line 4a extends. The direction in which the fold line 4a extends is sometimes referred to as the horizontal direction of the packaging bag 10.

[0026] In addition, sometimes Figure 1 The direction perpendicular to the paper is referred to as the front-to-back direction of the packaging bag 10. Of the pair of main body components 3 that sandwich the bottom member 4, one main body component 3 is positioned on the front side, and the other main body component 3 is positioned on the rear side. In the structure of the packaging bag 10, a strict distinction between the front and rear sides is not necessary. However, if a logo or pattern is prominent on one side, the prominent side may be designated as the front side. However, the packaging bag 10 of this embodiment may have logos or patterns on both the front and rear sides, or may be plain.

[0027] The resin layers of the main body member 3 and the bottom member 4 are formed of a film composed only of a polyethylene resin. The polyethylene resin film may be a single-layer resin film or a multi-layer resin film.

[0028] The main body film forming the main body member 3 and the bottom film forming the bottom member 4 may be films of the same material and thickness, or may be films of different materials and thickness.

[0029] The film forming the main body member 3 or the base member 4 may also be laminated with a vapor deposited layer, a printed layer, a coating layer, an adhesive layer, etc. as a different material layer other than the resin layer. Examples of the different material include metals such as aluminum, and inorganic compounds such as silicon dioxide and aluminum oxide.

[0030] In the case of a multi-layer resin film, it may be a laminated film having a sealant layer on the inner surface and a base material layer on the outer surface. The printing layer, coating layer, adhesive layer, etc. may also contain polymer materials other than polyethylene as materials for inks, coatings, adhesives, etc.

[0031] The heterogeneous material layer may be positioned between the sealant layer and the substrate layer of the film, or may be positioned further outward in the thickness direction of the substrate layer of the film. The method for forming the laminated film is not particularly limited, but examples thereof include dry lamination, extrusion lamination, thermal lamination, coextrusion, and coating. Different methods may be used for laminating each layer.

[0032] The sealant layer is a resin layer disposed on the inner surface of the film. The sealant layer serves to bond the main body components 3 to each other in the main body seal 1 and to bond the main body component 3 to the bottom component 4 in the bottom seal 2. The sealant layer is preferably formed from an unstretched polyethylene resin. Specific examples of materials forming the sealant layer include relatively low-density polyethylene resins such as linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE).

[0033] The substrate layer is a resin layer laminated on the outer side of the film in the thickness direction relative to the sealant layer. The substrate layer can be disposed on the outer surface of the film. The substrate layer is preferably formed from a stretched polyethylene resin. Specific examples of materials forming the substrate layer include relatively high-density polyethylene resins such as medium-density polyethylene (MDPE) and high-density polyethylene (HDPE).

[0034] The polyethylene resin may be a homopolymer of ethylene or a copolymer mainly composed of ethylene. Examples of monomers other than ethylene (comonomers) include α-olefins such as 1-butene, 1-hexene, and 1-octene, cyclic olefins such as norbornene, and vinyl monomers such as vinyl acetate, vinyl chloride, and acrylic acid.

[0035] When using a comonomer, one or more comonomers may be used. The proportion of ethylene in the monomers constituting the polyethylene resin polymer is preferably 50% by weight or more, for example, 80 to 100% by weight. Ethylene or the comonomer may be a compound derived from fossil resources such as petroleum, or a compound derived from biomass such as plants.

[0036] The material forming the above-mentioned film may contain additives other than the resin. Additives may be arbitrarily added to the sealant layer, substrate layer, or other layers. Although not particularly limited as additives, examples thereof include antioxidants, lubricants, anti-caking agents, flame retardants, ultraviolet absorbers, light stabilizers, antistatic agents, colorants, cross-linking agents, and the like. The material forming the above-mentioned film may be a single polyethylene resin or a combination of two or more polyethylene resins.

[0037] One main body member 3 is disposed on each of the front and rear sides of the packaging bag 10. The main body members 3 on the front and rear sides of the packaging bag 10 may be formed to have the same planar shape.

[0038] Main body seal portions 1 are formed on the left and right sides of the packaging bag 10 above the fold line 4a. In the main body seal portions 1, the inner surfaces of the front and rear main body members 3 are joined to each other along left and right peripheral edges 11.

[0039] The unsealed portion 5 between the main body sealed portions 1 in the left-right direction of the packaging bag 10 forms a space where the front and rear main body members 3 are not joined to each other and the content can be accommodated.

[0040] The bottom member 4 is sandwiched between the front and rear main body members 3 so that the folding line 4a is located on the upper side. The folding line 4a is the upper end of the bottom member 4 in a plan view.

[0041] A bottom seal 2 is formed below the fold line 4a, joining the inner surface of the bottom member 4 to the inner surface of the main body member 3. The front bottom seal 2 joins the lower portion 4b and side portions 4c of the bottom member 4, which are located further forward than the fold line 4a, to the front main body member 3.

[0042] The rear bottom seal portion 2 joins the lower portion 4 b and the side portions 4 c of the bottom member 4 , which are located rearward of the fold line 4 a , to the rear main body member 3 .

[0043] The unsealed portion 5 surrounded by the lower portion 4 b and the side portions 4 c of the bottom member 4 forms a space capable of storing contents without joining the bottom member 4 and the main body member 3 .

[0044] The boundary portion 2 a of the bottom sealed portion 2 with the unsealed portion 5 is convex downward at a center portion 2 b in the left-right direction of the packaging bag 10 .

[0045] The shape of the boundary portion 2a can be set according to the shape of the region where the lower portion 4b and the side portion 4c of the bottom member 4 are joined to the main body member 3. The boundary portion 2a is preferably a smoothly curved line.

[0046] The intersection point P between the main body seal portion 1 and the bottom seal portion 2 is a portion where the fold line 4 a of the bottom member 4 is sandwiched between the main body members 3 and joined.

[0047] The main body seal portion 1 overlaps two films by joining the front and rear main body members 3 , whereas the bottom seal portion 2 overlaps four films by joining the mountain-folded bottom member 4 between the front and rear main body members 3 .

[0048] Therefore, a height difference caused by a change in the number of overlapped films occurs at the intersection point P. When the bottom member 4 is extended forward and backward with the fold line 4a as the center, the bottom member 4 rotates with the intersection point P as a fulcrum.

[0049] like Figure 1 As shown, the boundary 2a between the bottom seal portion 2 and the unsealed portion 5 is convex toward the upper side of the packaging bag 10 at the side end 2c near the contact with the main body seal portion 1. In a plan view, a curved portion 2d may exist between the side end 2c and the center portion 2b, where the boundary 2a becomes substantially linear.

[0050] On either side portion 4c, if an extension line L of the curved portion 2d is drawn, it intersects the main body seal portion 1 located on the same side of the side portion 4c at a position above the fold line 4a. The intersection of the extension line L and the main body seal portion 1 is upwardly spaced from the intersection point P. When the curved portion 2d is used as a representative example of the inflection point, the extension line L of the curved portion 2d may be a tangent line at the inflection point. The intersection of the extension line L and the main body seal portion 1 is preferably spaced at least 5 mm from the intersection point P.

[0051] Regarding this distance, the intersection point may be located within the width of the main body sealing portion 1 , and may be, for example, the uppermost position, the lowermost position, or the center position in the width direction of the main body sealing portion 1 .

[0052] If the bottom member 4 is unfolded front and back, the packaging bag 10 can stand on its own with the bottom member 4 at the bottom in the vertical direction. Figure 2 As shown, if the bottom member 4 is viewed from the bottom side of the packaging bag 10 after being expanded forward and backward, the central portion 2b of the bottom seal portion 2 is easily expanded forward and backward, but the side end portions 2c of the bottom seal portion 2 are close to the main body seal portion 1 and are therefore difficult to expand forward and backward.

[0053] Furthermore, when the packaging bag 10 is filled with content, the load of the content acts along the boundary 2a in a direction that expands the gap between the main body member 3 and the bottom member 4. Consequently, stress in a direction that tends to cause the bond to separate is generated near the boundary 2a of the bottom seal 2 and near the intersection P of the main body seal 1.

[0054] In conventional packaging bags, the films forming the main body member 3 or bottom member 4 include a sealant layer made of PE or other materials and a base material such as PET. Thus, the sealant layer securely bonds the films together, while the base material such as PET enhances the mechanical strength of the films, thereby preventing delamination of the bond. However, when packaging bag 10 is formed solely from a polyethylene resin film without using a base material such as PET, the mechanical strength of the film decreases.

[0055] In conventional packaging bags, the boundary 2a between the bottom sealed portion 2 and the unsealed portion 5 is generally convex toward the bottom of the bag, or is generally straight near the side end 2c. Consequently, stress generated by the load of the contents on the main body 3 or bottom member 4 tends to concentrate near the intersection point P. Furthermore, because the intersection point P is located near the bottom corner 12 of the bag, it is susceptible to the impact of being dropped. Therefore, to ensure the impact resistance of the bag, the film material is limited, making it difficult to use a single material.

[0056] In the packaging bag 10 of the embodiment, the boundary portion 2a at the side end portion 2c of the bottom seal portion 2 is convex toward the upper side of the packaging bag 10. This improves the packaging bag's impact resistance and prevents peeling of the joints and bag breakage. Consequently, even if the packaging bag is dropped, it is less likely to break, resulting in a highly durable packaging bag.

[0057] According to the embodiment, the bottom sealed portion 2 near the intersection point P at the side end portion 2c is wider than the conventional sealed portion 2. Also, although the region where the bottom member 4 rotates about the fold line 4a is near the center portion 2b of the bottom sealed portion 2, as in the conventional case, the unsealed portion 5 near the side end portion 2c of the bottom sealed portion 2 is narrower than the conventional unsealed portion.

[0058] Therefore, when the bottom part 4 expands toward the front and rear of the packaging bag 10 with the fold line 4a as the center, and the main part 3 and the bottom part 4 expand with the boundary part 2a as the center, the movement of the main part 3 and the bottom part 4 can be suppressed more than before at the side end part 2c of the bottom sealing part 2.

[0059] When the load of the contents acts on the main body member 3 and the bottom member 4, the main body member 3 expands more because the width of the unsealed portion 5 near the center portion 2b of the bottom seal portion 2 is wide, and the distribution of the contents is also dispersed.

[0060] Depending on the degree of expansion of the unsealed portion 5 at the central portion 2b of the bottom seal portion 2, when the side end portion 2c of the bottom seal portion 2 attempts to expand toward the front and rear of the packaging bag 10, the degree of expansion is greater above the extension line L of the curved portion 2d, but the degree of expansion is more easily suppressed below the extension line L of the curved portion 2d.

[0061] Therefore, when the unsealed portion 5 of the main body member 3 expands, the area to which the force is applied tends to be dispersed above the extension line L of the bent portion 2d. In the area below the extension line L, the contents are less likely to enter the unsealed portion 5, and deformation of the main body member 3 or the bottom member 4 is suppressed.

[0062] As a result, even if an impact such as a drop is applied to the lower corner 12 of the packaging bag 10 , stress concentration near the intersection P below the extension line L can be alleviated, thereby suppressing separation of the joint and bag breakage.

[0063] like Figure 2 As shown, the bottom member 4 is preferably difficult to open forward and backward at the left and right side ends 2c of the bottom seal portion 2. Although not specifically shown, a notch or through hole can also be formed in the bottom member 4 so that the front and rear main body members 3 are joined through the notch or through hole.

[0064] The notch portion may be in contact with the left and right peripheral edge portions 11 . The through hole may be formed at a position away from the left and right peripheral edge portions 11 .

[0065] Alternatively, the outer surfaces of the bottom members 4 may be partially joined together. In this case, the cutouts or through-holes in the bottom members 4 may be omitted. The regions where the outer surfaces of the bottom members 4 are joined together may be in contact with the left and right peripheral edges 11 or may be spaced apart from the left and right peripheral edges 11.

[0066] The dimensions of the packaging bag 10 are not particularly limited, but for example, the height in the vertical direction is about 100 mm to 500 mm, the width in the horizontal direction is about 70 mm to 300 mm, and the filling volume is 100 cm 3 ~5000cm 3 about.

[0067] Examples of the state of the contents include fluids such as liquids, powders, and granules. Examples of the types of contents include, but are not particularly limited to, detergents, pharmaceuticals, cosmetics, medicines, beverages, seasonings, inks, coatings, and fuels.

[0068] In order to fill the packaging bag 10 with the contents, a portion of the filling port 6 may be opened in the periphery of the main body member 3 . Figure 2The packaging bag 10 shown is in a state where the front and rear body members 3 are joined to close the filling port 6. The filling port 6 before filling may be provided in a state where an unsealed portion is open between the front and rear body members 3.

[0069] Although Figure 2 The filling port 6 shown on the lower side of FIG. 1 is formed in the upper portion of the packaging bag 10 , but the position of the filling port 6 is not particularly limited, and the filling port 6 may be formed in either of the left and right peripheral portions 11 .

[0070] A pouring spout 7 may be opened at the periphery of the main body 3 to pour out the contents from the packaging bag 10. The direction of the pouring spout 7 is not particularly limited, but may be upward, left or right, or inclined relative to the packaging bag 10.

[0071] exist Figure 2 The lower side of FIG. 1 illustrates a pouring spout 7 having a flow path 7a formed obliquely above the packaging bag 10. Flow path forming seal portions 7b are formed around the pouring spout 7 on both sides of the flow path 7a.

[0072] Although Figure 2 The pouring spout 7 is shown in an open state, but it is preferable that the pouring spout 7 is closed before pouring out the contents.

[0073] At the front end of the flow path 7a before opening, a flow path sealing portion 7c may be formed continuously with the flow path forming sealing portion 7b to seal the flow path 7a. The flow path forming sealing portion 7b and the flow path sealing portion 7c may be formed by joining the inner surfaces of the front and rear main body members 3 to each other.

[0074] To facilitate separation of the flow path closing seal portion 7c when the pouring spout 7 is opened, an opening guide (not shown) may be formed by a cutout (notch) at the end or a half cut in the film.

[0075] The opening guide of the pouring spout 7 may be omitted and a tool such as scissors may be used to open the pouring spout 7. When the pouring spout 7 is provided with the opening guide, it is easy to open the spout 7 with fingers without using a tool.

[0076] A rigid component for maintaining the tubular shape of the flow channel 7a may also be joined to the pouring spout 7. For example, a shape-retaining component (not shown) molded from a polyethylene resin into a tubular or straw-like shape may be used. The shape-retaining component may be attached to either the inner surface of the flow channel 7a of the main body 3 or the outer surface of the main body 3.

[0077] As mentioned above, although the present invention has been described based on the preferred embodiment, the present invention is not limited to the above-mentioned embodiment, and various changes can be made without departing from the scope of the present invention.

Claims

1. A packaging bag, characterized in that: The packaging bag is formed by sandwiching a bottom part folded in half by a fold line between a pair of main body parts. A main body sealing portion is formed above the fold line of the packaging bag, and the main body sealing portion joins the inner surfaces of the pair of main body members to each other along the left and right peripheral edges of the packaging bag. A bottom seal portion is formed below the fold line of the packaging bag, and the bottom seal portion joins the inner surface of the bottom member to the inner surface of the main body member. The unsealed portion surrounded by the main body sealing portion and the bottom sealing portion can accommodate contents. The resin layers of the main body member and the bottom member are formed of a film consisting only of a polyethylene resin. The boundary between the bottom seal portion and the unsealed portion is convex toward the upper side of the packaging bag at a side end portion near the contact with the main body seal portion. The boundary between the bottom sealed portion and the unsealed portion is convex toward the lower side of the packaging bag at the center portion in the left-right direction of the packaging bag. Between the side end portion and the central portion, there is a curved portion having a substantially linear boundary between the bottom sealed portion and the unsealed portion. At a position higher than the fold line, the extension line of the curved portion intersects with the main body sealing portion, and the distance between the intersection points is more than 5 mm. The intersection point is the intersection point between the main body sealing portion and the bottom sealing portion, and is the portion where the fold line of the bottom component is clamped and joined between the main body components.

2. The packaging bag according to claim 1, characterized in that: The film is a laminated film having a sealant layer laminated on the inner surface of the film and a base material layer laminated on the outer side of the sealant layer in the thickness direction of the film. The sealant layer is formed of an unstretched polyethylene-based resin, and the base layer is formed of a stretched polyethylene-based resin.

3. The packaging bag according to claim 1 or 2, characterized in that: The outer surfaces of the bottom members are joined to each other at left and right peripheral edges of the packaging bag.

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