Method for manufacturing self-supporting packaging bag, sealing member used in manufacturing the self-supporting packaging bag, and self-supporting packaging bag manufactured by method for manufacturing the self-supporting packaging bag

Abstract

To provide a self-supporting packaging bag having a step portion based on overlapping of films, capable of reliably and sufficiently performing sealing at the vicinity of the step portion, having an excellent appearance at the step portion, and capable of preventing leakage of a content, and a manufacturing method thereof.SOLUTION: There is provided a method for manufacturing a self-supporting packaging bag. The self-supporting packaging bag is composed of a pair of flat portions 11 and a bottom portion 12 folded in half in an inverted V shape at a bottom, has a side seal portion 22 and a bottom seal portion 21, and has step portions 31 and 32 based on overlapping of films of a two-layer portion TL in which the pair of flat portions 11 overlap, and a four-layer portion FL in which the pair of flat portions 11 overlap the bottom portion 12. In a first sealing step including heating, pressurizing and cooling, the bottom seal portion 21 is formed with an area including at least a part of the step portions 31 and 32 as an unsealed portion 25, and the unsealed portion 25 is sealed after a second sealing step. There are also provided a sealing member used in the manufacturing method, and a self-supporting packaging bag SPB manufactured by the manufacturing method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a self-standing packaging bag, a seal member used for manufacturing the self-standing packaging bag, and a self-standing packaging bag manufactured by the method for manufacturing the self-standing packaging bag.

Background Art

[0002] Packaging bags made of film materials such as synthetic resins are well known. As a laminate constituting such a packaging bag, one provided with a seal layer made of a synthetic resin capable of heat-sealing on the innermost layer is known. By using such a laminate and heating and pressing a desired region, heat-sealing is performed to form a seal portion, and the packaging bag is formed in a bag shape.

[0003] A conventional self-standing packaging bag SPB-C shown in FIG. 12 having self-standing properties is known. The conventional self-standing packaging bag SPB-C shown in FIG. 12 has a bottom surface portion 12 folded in a reverse V shape at the lower part of a pair of flat portions 11, and has been made into a packaging bag by forming a conventional bottom surface seal portion 21C and side seal portions 22 on both side portions of the flat portion.

[0004] The conventional self-standing packaging bag SPB-C has side seal portions 22 on both side portions of the flat portion 11. Further, it has a boat-shaped conventional bottom surface seal portion 21C at the lower part, and the flat portion 11 and the bottom surface portion 12 are joined by the side seal portions 22 and the conventional bottom surface seal portion 21C. The conventional self-standing packaging bag SPB-C shown in Fig. 12, as shown in Fig. 13(a), has a bottom surface forming film 12 folded twice in an inverted V shape disposed at the lower part of a pair of flat surface forming films 11. As shown in Fig. 13(b), the bottom surface forming film 12 is sandwiched between the lower parts of the two films of the flat surface forming film 11. As shown in Fig. 13(c), first, the conventional bottom surface seal portion 21C is formed, and as shown in Fig. 13(d), side seal portions 22 are formed on both sides. At this time, cut portions 13 are provided at both ends of the bottom surface forming film 12 folded twice in an inverted V shape, and in the side seal portions 22, the innermost fusion layers of the pair of flat surface portions 11 are sealed through the cut portions 13.

[0005] Also, each of these seal portions is formed by a pair of seal jigs that cool after heating and pressurization. Note that if the sealing of all parts of the packaging bag is continuously heated and pressurized without cooling after heating and pressurization, heat fusion will occur up to unnecessary locations due to the residual heat. Therefore, it is necessary to perform cooling after heating and pressurization.

[0006] The conventional self-standing packaging bag SPB-C shown in Fig. 12 has a two-layer portion TL composed of a pair of flat surface forming films 11 that constitute the flat surface portion 11 of the self-standing packaging bag, a pair of flat surface forming films 11, and a four-layer portion FL composed of the bottom surface forming film 12 folded twice to form a double layer. The boundary between the two-layer portion TL and the four-layer portion FL is a stepped portion based on the overlap of the films. In the stepped portion, there are a first stepped portion 31 caused by the bottom surface forming film fold line 14 and a second stepped portion 32 caused by the cut portion 13 provided in the bottom surface forming film 12. Fig. 14 is a cross-sectional view of the first stepped portion 31 formed at the boundary between the two-layer portion TL and the four-layer portion FL in the conventional self-standing packaging bag SPB-C. As shown in FIG. 12, the side seal portion 22 and the conventional bottom surface seal portion 21C are seal portions that straddle the first step portion 31 and the second step portion 32. In particular, in the first step portion 31, the conventional bottom surface seal portion 21C seals the entire area of the step portion that overlaps with the side seal portion 22. However, due to the difference in thickness of the step portion, a difference in pressure from the seal bar occurs, resulting in insufficient sealing on the two-layer portion TL side near the step portion and insufficient adhesion in some cases. In that case, there was a risk that the contents would leak from this part. In particular, since the conventional bottom surface seal portion 21C mainly seals the four-layer portion FL, in the vicinity of the step portion, more specifically, on the two-layer portion TL side of the first step portion 31 formed at the boundary between the four-layer portion FL and the two-layer portion TL shown in FIG. 14, it is difficult to apply sufficient pressure, and the sealing tends to be insufficient. Note that 26 in FIG. 12 is an unsealed portion in the conventional bottom surface seal portion 21C, and is an unsealed portion provided to prevent wrinkles from occurring when the entire surface of the conventional bottom surface seal portion 21C is sealed, and is the conventional bottom surface unsealed portion 26. In order to solve such problems, various proposals have been made.

[0007] Patent Document 1 discloses a method for manufacturing a packaging bag, which includes a laminating step of forming a laminate in which a pair of side sheets are laminated with a bottom sheet folded in two therebetween, and an adhering step of adhering the side sheet and the bottom sheet of the laminate. The adhering step includes a first adhering step of heating and pressing the four-layer portion where the bottom sheet of the laminate is located to adhere the lower adhering portion, a second adhering step of heating and pressing the two-layer portion where the bottom sheet of the laminate is not located to adhere the side adhering portion, and a third adhering step of heating and pressing the boundary portion between the four-layer portion where the bottom sheet is located and the two-layer portion where the bottom sheet of the laminate is not located to adhere the boundary portion with the lower adhering portion in the side adhering portion. Patent Document 1 aims to provide a method for manufacturing a packaging bag with suppressed liquid leakage. In Patent Document 1, if the synthetic resin film forming the innermost heat-sealing layer is composed of a resin having a melting point, even if cooling is performed after each heating and pressurization in each sealing step, since the resin melts every time it is heated above the melting point, a strong seal can be ensured by repeatedly performing sealing with emphasis. Packaging bags made of polyethylene film or polypropylene film, which are frequently used as packaging bags, are based on this sealing mechanism.

[0008] On the other hand, as a packaging bag, there is a packaging bag used when enclosing pharmaceuticals and quasi-drugs containing active ingredients such as ship drugs in the contents, foods and cosmetics containing fragrances and spices in the contents, etc. For such packaging bags, there is a high demand for reducing the amount of fragrance, spice or active ingredient adsorbed on the bag and maintaining the content of fragrance, spice or active ingredient in the contents at a desired value. Therefore, in some cases, a laminate using a resin having high non-adsorbability as the innermost heat-sealing layer forms a packaging bag. As a non-adsorbing film used for this heat-sealing layer, Patent Document 2 discloses a layer made of an amorphous polyester copolymer having a glass transition point of 70 to 90°C. It is said that this can achieve both excellent non-adsorbability and seal strength, and is easy to form a film.

[0009] In the case of a packaging bag using a polyester-based resin with a high degree of amorphousness as the film forming the heat-sealing layer, it is possible to perform sealing by heating above the melting point. However, the melting point of the polyester-based resin is very high, around 250°C. When heated above the melting point of the polyester-based resin, the adjacent layer also melts, making it difficult to stably manufacture the packaging bag, and there was a risk that defects would occur in the manufactured packaging bag. Therefore, there is a method of softening and adhering by setting the heating temperature in the sealing step to be less than the melting point of the polyester-based resin with a high degree of amorphousness.

[0010] When manufacturing a self-supporting packaging bag using this method, in the sealing process of the stepped portion, if cooling is performed after heating and pressurization, the crystallization of the amorphous portion of the polyester resin will progress. Even if heating is performed again in the next sealing process, the crystallized molecules will maintain high crystallinity without returning to the amorphous state. Therefore, if the adhesion is insufficient in the first sealing process including heating, pressurization, and cooling, the crystallinity of the polyester molecules will increase while the adhesion remains insufficient no matter how many times sealing by heating and pressurization is performed thereafter, and sufficient adhesion cannot be achieved. There is a possibility that a strong seal cannot be ensured by the manufacturing method described in Patent Document 1.

[0011] Therefore, Patent Document 3 discloses a sealing method for manufacturing a self-supporting packaging bag using a laminate having a heat-sealing layer made of amorphous polyester. In the stepped portion where adhesion may be insufficient, a first step of overlapping the heat-sealing layers and joining them by sealing, and a second step of melting the stepped portion formed by further overlapping the two laminates joined in the first step by a sealing method such as an ultrasonic sealing method or a high-frequency dielectric sealing method with a larger heating amount than the sealing in the first step are provided. A sealing method for a packaging bag is disclosed.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0013] However, in the method for manufacturing a packaging bag disclosed in Patent Document 3, in addition to a heat-sealing mechanism, an ultrasonic sealing mechanism and a high-frequency dielectric sealing mechanism need to be separately provided. Therefore, the configuration of the bag-making apparatus becomes complicated, which is disadvantageous in terms of cost, maintenance, etc. Further, when ultrasonic sealing or high-frequency dielectric sealing is performed in addition to heat-sealing, the laminate in that portion becomes extremely thin and its strength is weakened. Furthermore, the resin of the heat-fusion layer in the thinned portion may melt and flow into the content accommodating portion, resulting in the generation of resin lumps. In addition, since ultrasonic sealing marks and high-frequency dielectric sealing marks remain visible on the packaging bag, the appearance of the packaging bag deteriorates.

[0014] The problem to be solved by the present invention is to provide a method for manufacturing a self-supporting packaging bag having a stepped portion based on the overlap of films, which can surely and sufficiently perform sealing near the stepped portion, has excellent appearance of the stepped portion, and can prevent the occurrence of leakage of contents, a sealing member used for manufacturing the self-supporting packaging bag, and a self-supporting packaging bag manufactured by using the method for manufacturing the self-supporting packaging bag.

Means for Solving the Problem

[0015] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by a specific method for manufacturing a self-supporting packaging bag, a sealing member used for manufacturing the self-supporting packaging bag, and a self-supporting packaging bag manufactured by the method for manufacturing the self-supporting packaging bag, and have completed the present invention. That is, the present invention provides a method for manufacturing the following packaging bag, a sealing member used for manufacturing the packaging bag, and a packaging bag manufactured by the method for manufacturing the packaging bag.

[0016] [Item 1] A method for manufacturing a self-supporting packaging bag composed of a pair of flat portions and a bottom portion folded in two in an inverted V shape at the lower part, having a side seal portion and a bottom seal portion, a two-layer portion where the pair of flat portions overlap, and a stepped portion based on the overlap of films of a four-layer portion where the pair of flat portions and the bottom portion overlap, comprising: In the first sealing step, the area including at least a part of the stepped portion is heated and pressed while leaving it as an unsealed portion, and then cooled to form the bottom surface sealing portion, and the unsealed portion is heated, pressed, and cooled in the second sealing step and subsequent steps to be sealed. A method for manufacturing the self-standing packaging bag. [Item 2] The method for manufacturing a self-standing packaging bag according to Item 1, wherein the pair of flat portions and the bottom surface portion are made of a film provided with a heat-sealing layer containing a polyester-based resin. [Item 3] A sealing member used in a method for manufacturing a self-standing packaging bag, which is composed of a pair of flat portions and a bottom surface portion folded in two in an inverted V shape at the lower part, has side surface sealing portions and a bottom surface sealing portion, and has a stepped portion based on the film overlap of a two-layer portion where the pair of flat portions overlap and a four-layer portion where the pair of flat portions and the bottom surface portion overlap. A heating and sealing mold for forming the bottom surface sealing portion in which at least a part of the stepped portion is an unsealed portion in the first sealing step. The sealing member. [Item 4] A self-standing packaging bag manufactured by the method for manufacturing a self-standing packaging bag according to Item 1 or 2. [Item 5] Composed of a pair of flat portions and a bottom surface portion folded in two in an inverted V shape at the lower part, having side surface sealing portions and a bottom surface sealing portion, and having a stepped portion based on the film overlap of a two-layer portion where the pair of flat portions overlap and a four-layer portion where the pair of flat portions and the bottom surface portion overlap. A method for manufacturing a self-standing packaging bag, using a bag-making machine having a plurality of sets of sealing jigs that are cooled after heating and pressing. The method for manufacturing a self-standing packaging bag, characterized in that there is an area that is sealed only by the last set of sealing jigs in the stepped portion. The method for manufacturing a self-standing packaging bag.

Effect of the Invention

[0017] In a method for manufacturing a self-standing packaging bag having a stepped portion based on the overlap of films, even when a film in which the heat-sealing layer is made of a polyester resin having a high degree of amorphousness is used, it is possible to surely perform the sealing of the stepped portion, and a method for manufacturing a self-standing packaging bag is provided which has excellent sealing appearance of the stepped portion and suppresses the occurrence of leakage of liquid contents. Further, a sealing member used for manufacturing this self-standing packaging bag and a self-standing packaging bag manufactured by using this method for manufacturing a self-standing packaging bag are provided.

Brief Description of Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

[0019] Hereinafter, a method for manufacturing a self-standing packaging bag according to the present invention, a seal member used in the method for manufacturing the self-standing packaging bag, and a self-standing packaging bag manufactured by the method for manufacturing the self-standing packaging bag will be described in detail.

[0020] [Method for Manufacturing a Self-Standing Packaging Bag] The method for manufacturing a self-standing packaging bag according to the present invention is composed of a pair of flat portions and a bottom surface portion folded twice in an inverted V shape at the lower part, has side seal portions and a bottom surface seal portion, and has a stepped portion based on the film overlap between a two-layer portion where the pair of flat portions overlap and a four-layer portion where the pair of flat portions and the bottom surface portion overlap. In a first sealing step, a region including at least a part of the stepped portion is heated and pressed while remaining an unsealed portion, and then cooled to form the bottom surface seal portion, and the unsealed portion is heated, pressed, and cooled in a second sealing step and subsequent steps to be sealed. The method for manufacturing the self-standing packaging bag is characterized in this.

[0021] Further, the method for manufacturing a self-standing packaging bag according to the present invention is composed of a pair of flat portions and a bottom portion folded in two in an inverted V shape at the lower part, having side seal portions and a bottom portion seal portion, and having a stepped portion based on the film overlap between a two-layer portion where the pair of flat portions overlap and a four-layer portion where the pair of flat portions and the bottom portion overlap. A method for manufacturing a self-standing packaging bag using a bag-making machine having a plurality of sets of seal jigs that are cooled after heating and pressurization, wherein there is a region that is sealed only by the last set of seal jigs in the stepped portion. This is the method for manufacturing the self-standing packaging bag.

[0022] The self-standing packaging bag manufactured by the method for manufacturing a self-standing packaging bag according to the present invention is not particularly limited as long as it is a self-standing packaging bag having a stepped portion based on the film overlap. These self-standing packaging bags may have, for example, a chuck or a stopper.

[0023] <Self-standing packaging bag> FIG. 1 is a schematic view of a self-standing packaging bag SPB manufactured by the method for manufacturing a self-standing packaging bag according to an embodiment of the present invention. Among the self-standing packaging bags SPB in this embodiment, a pair of flat portions 11, a bottom portion 12 having a cut portion 13, side seal portions 22, a two-layer portion TL, a four-layer portion FL, a first stepped portion 31, and a second stepped portion 32 are the same parts as those of the conventional self-standing packaging bag SPB-C, and will be described using the same reference numerals. The self-standing packaging bag SPB shown in Fig. 1 has a pair of flat portions 11 and a bottom portion 12 that is folded twice in an inverted V shape at the bottom. The self-standing packaging bag SPB includes a two-layer portion TL composed of a pair of flat portions 11 that constitute the flat portions 11, and a four-layer portion FL composed of a pair of flat portions 11 and a bottom portion 12 that is folded twice to form a double layer. The boundary between this two-layer portion TL and the four-layer portion FL is a stepped portion based on the overlap of the films. In particular, the stepped portion with the bottom film fold line 14 for forming the bottom portion 12 of the bottom portion 12 as the boundary is the first stepped portion 31. Also, the self-standing packaging bag SPB has side seal portions 22 on both sides and a bottom seal portion 21 at the bottom. The bottom seal portion 21 serves both as the lower end seal of the self-standing packaging bag SPB and the seal that determines the shape of the bottom portion of the self-standing packaging bag SPB. It is a seal portion in which a lower end seal 21a that extends linearly in the width direction at the lower end of the self-standing packaging bag SPB and a bottom shape forming seal 21b in which both sides are linear diagonal seals 21ba and the center is an arc-shaped seal 21bb are integrated. Further, due to the shape of the bottom seal portion 21 of the self-standing packaging bag SPB, a first unsealed portion 24a of the stepped portion, a second unsealed portion 24b of the stepped portion, and an unsealed portion 25 of the bottom portion are formed. The first unsealed portion 24a of the stepped portion is an unsealed portion that includes at least a part that overlaps with the first stepped portion 31. The second unsealed portion 24b of the stepped portion is an unsealed portion that includes at least a part that overlaps with the second stepped portion 32 caused by the cutout portion 13 provided in the bottom portion forming film 12. In the self-standing packaging bag SPB of Fig. 1, in order to prevent wrinkles from occurring by sealing the entire surface including the space between the bottom shape forming seal 21b and the lower end seal 21a, an unsealed portion 25 of the bottom portion is formed with the space between the bottom shape forming seal 21b and the lower end seal 21a as an unsealed portion. The unsealed portion 25 of the bottom portion includes the second unsealed portion 24b of the stepped portion. That is, the second unsealed portion 24b of the stepped portion and the unsealed portion 25 of the bottom portion are integrated. Also, the first unsealed portion 24a of the stepped portion is sealed by the side seal portion 22 and a stepped special seal portion 23 described later, and is not an unsealed portion in the self-standing packaging bag SPB. The shape of the bottom seal portion 21 determines the opening shape of the bottom portion to be circular, elliptical, etc., and the self-standing packaging bag SPB is provided with self-standing properties.

[0024] <Film> The film used in the method for manufacturing the self-supporting packaging bag SPB according to the present embodiment is not particularly limited as long as at least one surface thereof is a heat-sealing layer and the innermost layer that becomes the inner surface of the self-supporting packaging bag SPB can be a heat-sealing layer. For example, it may be a single-layer film composed only of a heat-sealing layer, or it may be a laminated film in which a heat-sealing layer is provided on at least one surface of a base material layer. In the present embodiment, it is preferable to use a laminated film in which one surface of the base material layer is a heat-sealing layer. Such a laminated film has a base material layer and a heat-sealing layer, and may have an intermediate layer or the like therebetween as necessary. As the laminated film, for example, the innermost layer that becomes the inner surface of the packaging bag is a heat-sealing layer, the outermost layer that becomes the surface of the packaging bag is a base material layer having heat resistance, and one or more intermediate layers may be provided between the base material layer and the heat-sealing layer. Note that, in a packaging bag made of a single-layer film composed only of a heat-sealing layer, since the sealing member in the sealing step directly contacts the heat-sealing layer, wrinkles are likely to occur on the surface of the packaging bag. Therefore, by laminating the heat-sealing layer and other layers such as a base material layer to form a laminate, the occurrence of wrinkles on the surface of the packaging bag can be suppressed.

[0025] (Heat-sealing layer) In the film used in the method for manufacturing the self-supporting packaging bag SPB according to the present embodiment, the heat-sealing layer is a layer that can adhere the heat-sealing layers to each other by applying heat and pressure. The resin constituting the heat-sealing layer is not particularly limited as long as it is a resin having heat-sealing properties. For example, one or more selected from the group consisting of polyester-based resins, polyolefin-based resins, acrylic-based resins, vinyl acetate-based resins, polyamide-based resins, etc. can be mentioned. In the present embodiment, the resin constituting the heat-sealing layer contains a polyester-based resin.

[0026] When using a resin composition containing a polyester resin as the heat-sealing layer, it is preferable to use a polyethylene terephthalate resin as the polyester resin. By controlling the crystallinity of polyester resins such as polyethylene terephthalate resins, heat-sealability can be imparted even when heated below the melting point.

[0027] As the one containing a polyester resin, generally, a polyester resin composition film obtained by forming a composition containing a polyester resin, a plasticizer, a binder, and a molding aid into a film can be used. The crystallinity of the polyester resin composition film can be controlled within a desired range by rapid cooling during film formation. By controlling the crystallinity, the polyester resin composition film can impart heat-sealability even when heated below the melting point. Furthermore, since the polyester resin has non-adsorbability to pharmaceutical active ingredients, fragrances, etc., it can have both non-adsorbability and heat-sealability with only the polyester resin composition film without laminating two layers of a non-adsorbing layer and a heat-sealing layer.

[0028] Examples of the polyester resin composition include, for example, a polyethylene terephthalate resin composition composed of 0.1 to 3 parts by mass of a styrene-(meth)methyl acrylate-glycidyl methacrylate copolymer as a binder, 3 to 20 parts by mass of a cyclohexanedimethanol-ethylene glycol-terephthalic acid condensation polymer (PCTG) as a plasticizer, and 0.05 to 1.5 parts by mass of calcium stearate as a molding aid per 100 parts by mass of polyethylene terephthalate. As the polyethylene terephthalate, those having an intrinsic viscosity of, for example, 0.6 dl / g or more and 0.8 dl / g or less can be used. Also, the epoxy value in the styrene-(meth)methyl acrylate-glycidyl methacrylate copolymer is, for example, 0.5 meq / g or more and 4.0 meq / g or less.

[0029] The range of the crystallinity of the polyester resin in the heat-sealing layer for exhibiting heat-sealing properties even when heated below the melting point is, for example, 30% or less, preferably 25% or less, more preferably 20% or less, and even more preferably 18% or less. The lower limit can be 0%. The crystallinity of the polyester resin in this embodiment is within this range. The crystallinity is calculated by multiplying the value obtained by dividing the heat of fusion when melting the polyester by the heat of fusion of a perfect crystal (140 J / g in the case of polyethylene terephthalate) by 100 using a differential scanning calorimeter (DSC). Note that the above composition of the polyester resin in the heat-sealing layer is an example and is not limited thereto. Furthermore, the resin of the heat-sealing layer is not limited to the polyester resin. In this embodiment, the resin constituting the heat-sealing layer contains a polyester resin, but any heat-sealing layer can be preferably used.

[0030] (Base material layer) In the film used in the method for manufacturing a self-supporting packaging bag according to this embodiment, the base material layer of the laminated film is not particularly limited, and those having good mechanical properties and printing properties are preferable. Examples of such a base material layer include synthetic resin films such as polyester resin films (such as polyethylene terephthalate resin films), polyamide resin films (such as nylon resin films), polyolefin resin films (such as polypropylene resin films), cyclic olefin resin films (such as polynorbornene resin films and polydicyclopentadiene resin films), polyvinyl alcohol resin films (such as polyvinyl alcohol resin films and ethylene-vinyl alcohol copolymer resin films), polycarbonate resin films, and polyacetal resin films, multilayer coextruded films of these resins, laminates of these resins or films, non-woven fabrics, paper, metal foils, and the like. These films may be non-stretched films or stretched films stretched in one or two directions. In addition, as the film used for the base material layer, a vapor deposition film provided with a vapor deposition layer may be used. Examples of the vapor deposition layer include a layer made of one or more inorganic substances selected from the group consisting of aluminum, silicon oxide, aluminum oxide, indium oxide, tin oxide, zirconium oxide, magnesium oxide, and the like.

[0031] The thickness of the base material layer is not particularly limited. For example, it is 3 μm or more, preferably 5 μm or more, more preferably 6 μm or more, still more preferably 9 μm or more, and for example, it is 100 μm or less, preferably 60 μm or less, more preferably 50 μm or less.

[0032] (Intermediate layer) In the film used in the method for manufacturing a self-supporting packaging bag according to the present embodiment, it is preferable that the intermediate layer of the laminated film is formed from a material having barrier performance from the viewpoint of protecting the contents. The barrier performance includes light shielding properties against light rays such as visible light and ultraviolet rays, gas barrier properties against gases such as oxygen and water vapor, heat shielding properties for blocking heat, etc. Among these barrier performances, a material having a desired function is used as the intermediate layer.

[0033] The material having barrier performance is not particularly limited. Examples include metal foils such as aluminum, iron, copper, and tin, and films such as polyvinyl chloride, polycarbonate, polyvinyl alcohol, saponified ethylene-vinyl acetate copolymer, and polyvinylidene chloride. Further, a film obtained by coating polyvinylidene chloride on the film described for the base material layer, a film obtained by vapor-depositing inorganic substances such as aluminum, silicon oxide, aluminum oxide, indium oxide, tin oxide, zirconium oxide, and magnesium oxide on these films, a non-woven fabric having heat insulation properties, and a foamed film.

[0034] In addition to or instead of the barrier performance, the intermediate layer may have various functions. As the functions of the intermediate layer, for example, mechanical toughness, flex resistance, puncture resistance, impact resistance, cold resistance, heat resistance, chemical resistance, tear resistance, etc. can be appropriately selected according to the required and / or requested functions. The film used as the intermediate layer may be an unstretched film or a stretched film stretched in a uniaxial or biaxial direction. Further, the intermediate layer may be not only a single layer but also two or more layers.

[0035] The thickness of the intermediate layer is not particularly limited. For example, it is 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and for example, 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less.

[0036] (Laminating method of the laminated film) In the film used in the method for manufacturing a self-supporting packaging bag according to the present embodiment, when a laminated film is used, the laminating method of each layer of the base material layer, the heat-sealing layer, and the intermediate layer (if provided) constituting the laminated film is not particularly limited. For example, conventionally known laminating methods such as a dry laminating method, an extrusion laminating method, a non-solvent laminating method, a thermal laminating method, and a co-extrusion method can be applied, and if necessary, a plurality of laminating methods may be combined.

[0037] In the case of forming a heat-sealing layer that controls the crystallinity of the polyester resin to impart heat-sealing properties, since heat application in the laminating process may affect the heat-sealing properties, a laminating method that does not promote the crystallization of polyester, such as a dry laminating method or a non-solvent laminating method, is preferred.

[0038] <Manufacturing method of the self-supporting packaging bag according to the embodiment> The manufacturing method of the self-supporting packaging bag SPB according to the present embodiment is a method used for manufacturing a self-supporting packaging bag mainly when the resin constituting the heat-sealing layer of the film contains a polyester resin. Hereinafter, in the manufacturing method of the self-supporting packaging bag SPB according to the present embodiment, the manufacturing method of the self-supporting packaging bag SPB when the heat-sealing layer of the film contains a polyester resin will be described by a method of continuously manufacturing the self-supporting packaging bag SPB.

[0039] Figure 2 is a schematic diagram showing a state where the upper openings Ap of two self-standing packaging bags SPB are butted against each other, and a pair of films 11 for forming flat portions and a pair of films 12 for forming two-folded bottom portions are overlapped and conveyed so that the self-standing packaging bags SPB can be continuously manufactured. In Figure 2, each film is conveyed from the film roll on the right side (not shown) toward the left side, and two bags with the upper openings Ap of the self-standing packaging bags SPB butted against each other are manufactured in the width direction of the film 11 for forming flat portions. The pair of films 11 for forming flat portions are conveyed with the heat-sealing layers facing each other. Then, at both side portions in the conveying direction, between the pair of films 11 for forming flat portions, with the heat-sealing layer on the front side, the film 12 for forming the bottom portion that is two-folded along the bottom portion forming film fold line 14 is sandwiched and conveyed with the bottom portion forming film fold lines 14 facing each other. Note that the film 12 for forming the bottom portion is provided with cut portions 13 at regular intervals.

[0040] Figure 3 is a schematic diagram of the film 12 for forming the two-folded bottom portion sandwiched between the pair of films 11 for forming flat portions. In Figure 3, the cutting planned line 15 is the boundary line between the packaging bags when they become the self-standing packaging bags SPB, and is the line along which cutting is performed after sealing. As shown in Figure 3, after the film 12 for forming the bottom portion is fed out from the film roll, cut portions 13 are provided at regular intervals at positions that will become both side portions of the self-standing packaging bag.

[0041] As shown in Figures 2 and 4(a), the pair of films 11 for forming flat portions and the film 12 for forming the two-folded bottom portion are overlapped while being conveyed. Thereby, a first step portion 31 with the bottom portion forming film fold line 14 in the film 12 for forming the two-folded bottom portion as the boundary, and a second step portion 32 with the edge of the cut portion 13 as the boundary are formed. Fig. 4(b) shows a cross-sectional view of a state in which a pair of films 11 for forming flat portions and a film 12 for forming a bottom portion folded in half are stacked therebetween. As shown in Fig. 4(b), the first step portion 31 is defined by a folding line 14 of the film for forming the bottom portion, and includes a two-layer portion TL composed of a pair of films 11 for forming flat portions, and a four-layer portion FL formed by sandwiching the film 12 for forming the bottom portion folded in half between the pair of films 11 for forming flat portions. The first step portion 31 is formed at the boundary between the two-layer portion TL and the four-layer portion FL. The second step portion 32 is formed at the boundary between the four-layer portion FL and the two-layer portion TL, which is the edge of the cutout portion 13, in the four-layer portion FL formed by sandwiching the film 12 for forming the bottom portion folded in half between the pair of films 11 for forming flat portions, due to the cutout portion 13 formed in the film 12 for forming the bottom portion. Note that the cross-sectional view of the first step portion 31 is the same as that of the prior art shown in Fig. 14.

[0042] As described above, the method for manufacturing the self-standing packaging bag in the present embodiment sandwiches and stacks the film 12 for forming the bottom portion folded in half between the pair of films 11 for forming flat portions as shown in Fig. 4(b), and first forms the bottom portion seal portion 21 in the first sealing step.

[0043] (First Sealing Step) In the first sealing step in this embodiment, the bottom surface sealing portion 21 is formed. FIG. 5 shows a schematic diagram of the first sealing step. FIG. 5 is a view of one bag during continuous production of the self-supporting packaging bag SPB. The bottom surface sealing portion 21 also serves as the lower seal of the self-supporting packaging bag SPB and the seal that determines the shape of the bottom surface portion of the self-supporting packaging bag SPB. The detailed overall shape will be described later. In the first sealing step, in the first stepped portion 31, a region including a part that overlaps the side sealing portion 22 to be sealed later is heated and pressed, and then cooled to form the bottom surface sealing portion 21. At that time, the first stepped portion unsealed portion 24a is formed without sealing a region including at least a part of the remaining portion of the first stepped portion 31 that overlaps the side sealing portion 22 to be sealed later, which is the bottom surface forming film fold line 14. In FIG. 5, the positions between the left and right ends of the self-supporting packaging bag SPB and the side sealing portion boundary line 16 are the positions of the left and right side sealing portions 22, respectively. The bottom surface sealing portion 21 may be formed such that the first stepped portion 31 that overlaps the side sealing portion 22 is not sealed at all. However, it is preferable to seal only a part of the first stepped portion 31 that overlaps the side sealing portion 22 because it prevents displacement between the flat surface forming film 11 and the bottom surface forming film 12. The sealing member, which is a heat-sealing mold used to form the bottom surface sealing portion 21, forms the first stepped portion unsealed portion 24a without sealing a region including at least a part of the first stepped portion 31 that overlaps the side sealing portion 22, and has a shape that seals a region including a part of the first stepped portion 31 that overlaps the side sealing portion 22 other than the first stepped portion unsealed portion 24a. Details of this sealing member will be described later.

[0044] Here, in the method for manufacturing a self-supporting packaging bag in this embodiment, the heat-sealing layer containing a polyester resin used for the film is heated and pressed below the melting point of the polyester resin, so that the films are joined together, and by cooling this, the heat-melting characteristics are lost and it is sealed. Once cooled, the polyester resin will not remelt even if heated again. For this reason, when manufacturing a self-supporting packaging bag using the heat-sealing layer containing a polyester resin, as in the prior art, if the entire area of the first stepped portion 31 that overlaps with the side seal portion 22 at the conventional bottom seal portion 21C is sealed, in the two-layer portion TL side of the first stepped portion 31, if the films are not sufficiently joined, the molecules will crystallize as they are, the degree of crystallinity will increase, and the heat-melting characteristics will be lost. Even if the first stepped portion 31 where the films are not sufficiently joined is reheated in a subsequent sealing process, since the molecules that have once crystallized maintain the crystalline state, the heat-melting characteristics will not be restored, the joining of the films will remain insufficient, and there is a risk that this portion will become a sealing defect when it becomes a self-supporting packaging bag.

[0045] In the method for manufacturing the self-supporting packaging bag SPB according to this embodiment, in the first sealing process, the bottom seal portion 21 is heated and pressed and then cooled, whereby an unsealed portion 24a of the first stepped portion, which includes at least a part that overlaps with the side seal portion 22, is formed without sealing. At this point, the heat-sealing layers in the unsealed portion 24a of the first stepped portion are not fused, and it is possible to prevent the polyester resin in the heat-sealing layer in the unsealed portion 24a of the first stepped portion from crystallizing. After the heating and pressing in the first sealing process and the subsequent cooling are completed, the unsealed portion 24a of the first stepped portion is an unsealed portion where the films are not joined at all. The unsealed portion 24a of the first stepped portion is heated, pressed, and cooled only once in the last sealing process after the second sealing process described later to perform a strong seal.

[0046] Similarly, in the first sealing step of the present embodiment, the region including the second step portion 32 is not sealed, and the bottom surface sealing portion 21 is formed with the unsealed portion 24b of the second step portion. At this point, the heat fusion layers of the pair of flat surface forming films 11 of the two-layer portion TL in the unsealed portion 24b of the second step portion, and the heat fusion layers of the flat surface forming film 11 of the four-layer portion FL and the bottom surface forming film 12 are not joined, and crystallization of the polyester resin in the heat fusion layer can be prevented. After the first sealing step is completed, the unsealed portion 24b of the second step portion is an unsealed portion where the films are not joined at all.

[0047] FIG. 6 shows a bottom surface forming seal member 41 for forming the bottom surface seal portion 21 in the first sealing step. The bottom surface seal portion 21 also serves as the lower end seal of the self-supporting packaging bag SPB and the seal that determines the shape of the bottom surface of the self-supporting packaging bag SPB. As long as it can form the bottom surface of the self-supporting packaging bag SPB, its shape and the like are not particularly limited. In FIG. 5, the bottom surface seal portion 21 is a seal portion in which a lower end seal 21a extending linearly in the width direction at the lower end of the self-supporting packaging bag SPB and a bottom surface shape forming seal 21b composed of an arc-shaped seal 21bb in the center with linear diagonal seals 21ba on both sides are integrated. Also, the lower end seal 21a and the arc-shaped seal 21bb partially overlap. Both outer sides of the diagonal seal 21ba are the unsealed portion 24a of the first step portion, and the portion between the bottom surface shape forming seal 21b and the lower end seal 21a is the unsealed portion 24b of the second step portion. In the first sealing step, by first forming the bottom surface seal portion 21, displacement of the pair of flat surface forming films 11 and the bottom surface forming film 12 can be prevented.

[0048] The bottom surface forming seal member 41 used in the first sealing step shown in Fig. 6 is a heat sealing die for forming the bottom surface seal portion 21, has the same shape as the bottom surface seal portion 21, and has a bottom surface shape forming seal forming portion 44 for forming the bottom surface shape forming seal 21b and a lower end seal forming portion 45 for forming the lower end seal 21a. Further, the bottom surface forming seal member 41 has a step cutout portion 42 that can form a first step unsealed portion 24a in which at least a part of the step portion based on the overlap of the films is not sealed. The bottom surface forming seal member 41 shown in Fig. 6 is configured such that at least a part of either the first step portion 31 or the second step portion 32 is not sealed. Corresponding to the first step portion 31, a step cutout portion 42 for forming the first step unsealed portion 24a is formed, and corresponding to the second step portion 32, a side cutout portion 43 for forming the second step unsealed portion 24b is formed. In Fig. 6, the shape of the bottom surface forming seal member 41 is configured such that the entire length of the second step portion 32 is not sealed at the side cutout portion 43, but at least a part of the second step portion 32 may not be sealed. Further, since wrinkles may occur when planar sealing is performed at the bottom surface seal portion 21, in addition to the side cutout portion 43 that avoids the second step portion, a cutout portion for forming an unsealed bottom surface portion 25 (not shown) may be provided. The cutout portion for forming the unsealed bottom surface portion 25 may be configured separately from the side cutout portion 43, or may be formed integrally with the step cutout portion 42 and / or the side cutout portion 43.

[0049] Note that the second step portion 32 is not related to the content accommodating portion of the self-standing packaging bag SPB, and it is not necessary to form a seal having a strong seal strength sufficient to surely fill the step as required for the first step portion 31. For this reason, in the first sealing step, the side cutout portion 43 may not be provided in the bottom surface forming seal member 41 so as not to provide the unsealed portion 24b of the second step portion. Note that if the side cutout portion 43 or a cutout portion for forming the unsealed portion 25 of the bottom surface portion is not provided in the bottom surface forming seal member 41 and the bottom surface seal portion 21 is sealed in a planar shape, wrinkles may occur as described above. Therefore, it is preferable to provide a cutout portion so that at least a part of the second step portion 32 is not sealed.

[0050] In the present embodiment, in the side seal portion 22 to be sealed in a later step, in order to prevent the polyester resin of the heat fusion layer from crystallizing after the first sealing step, so that the pair of flat portion forming films 11 are joined via the cutout portion 13 of the bottom surface forming film 12 and the side portion of the self-standing packaging bag SPB is closed, it is desirable to avoid joining the flat portion forming films 11 corresponding to the cutout portion 13 in the first sealing step. Therefore, it is preferable to use the bottom surface forming seal member 41 having a cutout portion for forming the side cutout portion 43 and the unsealed portion 25 of the bottom surface portion, which forms the bottom surface seal portion 21 such that at least a part of the second step portion 32 overlapping the side seal portion 22 is not sealed.

[0051] The step portion notch 42 is provided in the bottom surface forming seal member 41 to form the unsealed portion 24a of the first step portion. That is, when the bottom surface forming seal member 41 is used in the first sealing step, the unsealed portion 24a of the first step portion is formed, and the region including at least a part of the first step portion 31 overlapping the side seal portion 22 is not sealed. The step portion notch 42 in the bottom surface forming seal member 41 is, for example, as shown in FIG. 6, the positions at both ends of the diagonal seal forming portion 44a in the bottom surface shape forming seal forming portion 44 are located inward by the width dimension d from the positions at both ends of the lower end seal forming portion 45, and the portion of the width dimension d located at the tip of the diagonal seal forming portion 44a becomes the step portion notch 42. The bottom surface seal portion 21 using this bottom surface forming seal member 41 extends to within the range overlapping the side seal portion 22 when the diagonal seal 21ba becomes the self-supporting packaging bag SPB, and does not reach the positions on both sides of the flat portion 11. As a result, the space between both ends of the diagonal seal 21ba and both sides of the flat portion 11 becomes the unsealed portion 24a of the first step portion including a part of the first step portion 31, and is formed so as not to be sealed. The shape of the step portion notch 42 is not limited to this, and any shape that can form an unsealed portion so that at least a part of the first step portion 31 overlapping the side seal portion 22 becomes the unsealed portion 24a of the first step portion may be used. In FIG. 6, the shape of the bottom surface forming seal member 41 is such that both ends of the diagonal seal forming portion 44a extend linearly in the vertical direction. However, for example, both ends of the diagonal seal forming portion 44a may be convex or concave arc-shaped, or may be linearly extending obliquely. Further, the shape of the bottom surface forming seal member 41 may be such that the periphery of the unsealed portion 24a of the first step portion is surrounded by a seal portion, and the bottom surface seal portion 21 is formed such that a part of the first step portion 31 overlapping the side seal portion 22 becomes an unsealed portion.

[0052] In the bottom surface forming seal member 41, the size of the step portion notch 42 for making the region including at least a part of the first step portion 31 the unsealed portion 24a of the first step portion is not particularly limited. In the step portion notch 42 of the bottom surface forming seal member 41 shown in FIG. 6, it is, for example, 80% or less, preferably 70% or less, more preferably 50% or less with respect to the width of the side seal portion 22 formed on one side, and it is preferable that, for example, 5% or more, preferably 10% or more, more preferably 20% or more is not sealed. In the bottom surface forming seal member 41 shown in FIG. 6, a side notch 43 for forming the second step portion unsealed portion 24b may be provided in the region including the second step portion 32. When the side notch 43 is provided, it is, for example, 100% or less, preferably 80% or less, more preferably 70% or less, still more preferably 50% or less with respect to the total length of the second step portion 32, and it is preferable that, for example, 0% or more, preferably 5% or more, more preferably 10% or more, still more preferably 20% or more is not sealed.

[0053] The heating temperature in the first sealing step of forming the bottom surface seal portion 21 is appropriately set according to the resin of the heat fusion layer. In the present embodiment, since the heat fusion layer contains a polyester resin, it is about 260°C or less, which is the melting point of the polyester resin, and for example, it can be 130°C or more and 160°C or less. If heated to a temperature equal to or higher than the melting point of the polyester resin, when the layers other than the heat fusion layer in the flat surface forming film 11 and / or the bottom surface forming film 12 are made of a polyester resin or an olefin resin, the resins of these layers will also melt. Therefore, it is preferable to heat at a temperature lower than the melting point of the polyester resin. A polyester resin is used for the heat fusion layer, heated at a temperature lower than the melting point of the polyester, and the polyester resin is softened to bond the films together. This is considered to be due to the active movement of amorphous polyester molecules and the entanglement of the amorphous molecules to bond the films together, and a strong seal portion is formed by cooling this.

[0054] In the first sealing step, the bottom surface forming seal member 41 is used for heating and pressurizing, and then cooling to form a strong bottom surface seal portion 21. In the first sealing step, if cooling is not performed after heating and pressing, the film 11 for forming the flat portion and the film 12 for forming the bottom portion may shift, and there is also a risk of adhesion to unnecessary portions due to residual heat. Therefore, cooling after heating and pressing must be performed. After the first sealing step is completed, the unsealed portion 24b of the second stepped portion is an unsealed portion where the films are not joined at all.

[0055] (Second Sealing Step) FIG. 7(a) is a schematic view of the second sealing step performed after the first sealing step, and FIG. 7(b) is an enlarged view of the circled portion in FIG. 7(a). As shown in FIGS. 7(a) and 7(b), the stepped portion special sealing portion 23 is formed in the second sealing step. The second sealing step is a step of sealing by focusing on heating and pressing the unsealed portion 24a of the first stepped portion including the first stepped portion 31 that was not sealed in the first sealing step. The stepped portion special sealing portion 23 formed in the second sealing step is within the region of the side portion sealing portion 22 to be sealed later, and is a region including the unsealed portion 24a of the first stepped portion that was not sealed in the first sealing step.

[0056] The heating temperature in the second sealing step is not particularly limited. In order to perform focused sealing, it is preferably below the melting point of the polyester resin of the heat-fusible layer and higher than the first sealing step. For example, it is 150 ° C or higher, preferably 170 ° C or higher, more preferably 200 ° C or higher, and for example, 240 ° C or lower, preferably 230 ° C or lower. In order to prevent the occurrence of an unsealed portion that is not sealed in either the first sealing step or the second sealing step due to a shift in the sealing position, the stepped portion special sealing portion 23 formed in the second sealing step is preferably made to partially overlap with the bottom portion sealing portion 21 in the first sealing step. The shape and size of the stepped special seal portion 23 formed in the second sealing step are such that sufficient heat and pressure can be applied to both the two-layer portion TL and the four-layer portion FL near the first stepped portion 31, and the first unsealed stepped portion 24a including the first stepped portion 31 formed in the first sealing step can be firmly joined, and it is not particularly limited as long as it fits within the region of the side seal portion 22 to be sealed later. For example, a rectangular shape, an elliptical shape, etc. with the same width as the side seal portion 22 to be sealed later and a height in the vertical direction of about 10 mm to 30 mm are preferable. The sealing member used in the second sealing step is suitable for this sealing shape.

[0057] After the second sealing step, without performing cooling, cooling is performed after heating and pressing in the third sealing step of forming the side seal portion 22 so as to include the stepped special seal portion 23 formed in the second sealing step. Since cooling is not performed after the second sealing step, the region of the first unsealed stepped portion 24a formed in the first sealing step and the stepped special seal portion 23 formed by performing sealing in the second sealing step can suppress an increase in the crystallinity of the polyester-based resin of the heat-sealing layer even after the second sealing step. Note that since the second stepped portion 32 caused by the cut portions 13 formed on both side portions of the bottom surface forming film 12 does not communicate with the content accommodating portion, it is not necessary to obtain a strong seal and it is not necessary to perform sealing in the second sealing step, but sealing may be performed.

[0058] (Third Sealing Step) FIG. 8(a) is a schematic view of the third sealing step performed after the second sealing step, and FIG. 8(b) is an enlarged view of the circled portion in FIG. 8(a). The third sealing step is a step of performing sealing at positions on both side portions of the self-supporting packaging bag SPB to form the side seal portion 22. In the third sealing step, the side seal portion 22 is formed by heating and pressing the region including the stepped special seal portion 23 formed in the second sealing step and then cooling.

[0059] In the third sealing step, the heating temperature is not particularly limited. For example, it is 150°C or higher, preferably 170°C or higher, more preferably 180°C or higher, and for example, 230°C or lower, preferably 220°C or lower, more preferably 210°C or lower. The shape and size of the side seal portion 22 formed in the third sealing step are not particularly limited as long as they can reliably seal both side portions of the self-standing packaging bag SPB. Generally, it is linear and extends from the upper end to the lower end in the vertical direction of the self-standing packaging bag SPB, and the width is preferably 5 mm or more and 30 mm or less. The side seal member used in the third sealing step is suitable for this seal shape.

[0060] In the third sealing step, by using a side seal member for forming and heating and pressing, and then cooling, the stepped special seal portion 23 formed in the second sealing step and the side seal portion 22 formed in the third sealing step are firmly sealed. In the first stepped unsealed portion 24a, there is no cooling between the two sealing steps of the second sealing step and the third sealing step, and after two heating and pressing operations, cooling is performed after the third sealing step. Therefore, a strong stepped special seal portion 23 is formed after the third sealing step.

[0061] (Cutting step) In the present embodiment, by the following cutting step, it is cut along the cutting planned line 15 so as to become individual self-standing packaging bags SPB, and the self-standing packaging bag SPB shown in FIG. 1 is obtained. After filling the content from the upper opening Ap of the obtained self-standing packaging bag SPB, the upper opening Ap is sealed to obtain a self-standing package.

[0062] The manufacturing method of the self-standing packaging bag according to the present embodiment is not limited to a manufacturing method in which the stepped special seal portion 23 is heat-pressed and sealed in the second sealing step, and the side seal portion 22 is heat-pressed and sealed in the third sealing step and then cooled. For example, in the second sealing step, the side seal portion 22 is heated and pressed, and without cooling, in the third sealing step, the stepped portion special seal portion 23 is heated and pressed for sealing, and then the region of the side seal portion 22 is cooled. A manufacturing method can also be adopted.

[0063] As described above, the manufacturing method of the self-supporting packaging bag in the present embodiment can surely perform sealing in the vicinity of the first stepped portion 31 based on the overlap of the films even when using a film composed of a heat-sealing layer containing a polyester resin containing an amorphous portion. The self-supporting packaging bag manufactured by this manufacturing method has an excellent appearance of the first stepped portion 31 and can prevent leakage of the contents after filling the contents.

[0064] In addition, the manufacturing method of the self-supporting packaging bag according to the present invention uses a bag-making machine having a plurality of sets of sealing jigs that are cooled after heating and pressing. In the manufacturing method of the self-supporting packaging bag according to the present embodiment, the heating and pressing in the first sealing step and the subsequent cooling are performed by the first set of sealing jigs, and the heating and pressing in the second and third sealing steps and the subsequent cooling are performed by the last second set of sealing jigs.

[0065] Specifically, first, by the first set of sealing jigs, after heating and pressurizing in the first sealing step and then cooling, a bottom surface sealing portion 21 is formed so as to form a first stepped portion unsealed portion 24a that overlaps the side sealing portion 22 of the self-standing packaging bag SPB and includes a part of the first stepped portion 31 and in which a region including a part of the first stepped portion 31 is not sealed. As described above, at this point, the films of the first stepped portion unsealed portion 24a are not joined to each other. This is to prevent crystallization of the polyester-based resin at this point because the heat-sealing layer of the film used for the self-standing packaging bag SPB of the present embodiment contains a polyester-based resin. Since cooling has been performed by the first set of sealing jigs, a strong bottom surface sealing portion 21 is formed. Then, by the last second set of sealing jigs, the above region and the side portion of the self-standing packaging bag SPB are heated and pressurized in the second sealing step and the third sealing step, respectively, and then cooled to form a stepped portion special sealing portion 23 and a side sealing portion 22. At this point, strong sealing portions are formed in all of the bottom surface sealing portion 21, the stepped portion special sealing portion 23, and the side sealing portion 22, and the sealing in the first stepped portion 31 can be surely and sufficiently performed. When the appearance of the first stepped portion 31 is excellent and the self-standing packaging bag SPB is obtained, even when the interior is filled with contents, leakage of the contents can be prevented.

[0066] As described above, the method for manufacturing a self-standing packaging bag according to the present embodiment is a case where a film made of a heat-sealing layer containing a polyester-based resin containing an amorphous portion is used. Even in this case, the first set of sealing jigs that perform heating, pressurization, and cooling below the melting point of the polyester-based resin are used to avoid a stepped portion based on the overlap of the films and perform sealing. Then, the region including the stepped portion where sealing was not performed by the first set of sealing jigs is sealed by the second set of sealing jigs for the last heating, pressurization, and cooling, so that the joining at the stepped portion can be surely performed, and seal failure that leads to leakage of the contents from the self-standing packaging bag can be suppressed. Furthermore, since the method for manufacturing the self-supporting packaging bag according to the present embodiment does not require separately providing an ultrasonic sealing mechanism, a high-frequency dielectric sealing mechanism, etc. described in Patent Document 3, it is advantageous in terms of the cost and maintenance of the bag-making apparatus. It can prevent the part from becoming extremely thin and weakening in strength due to ultrasonic sealing or high-frequency dielectric sealing, or the resin of the heat-sealing layer in the thinned part from melting and flowing into the content accommodating part to form resin masses. Also, since there is no generation of sealing marks due to ultrasonic sealing or high-frequency dielectric sealing, the appearance of the manufactured self-supporting packaging bag SPB is also good.

[0067] [Sealing member] The sealing member according to the present invention is a heat-sealing mold for forming the bottom surface sealing part used in the first sealing step in the method for manufacturing a self-supporting packaging bag, and is a sealing member for forming the bottom surface part. The sealing member according to the present invention is as described in detail above, and is configured in a shape having a notch so that at least a part of the stepped part based on the overlap of the films is not sealed.

[0068] FIG. 9 shows a sealing member for forming the bottom surface part 41, which is a sealing member according to an embodiment of the present invention, and is a schematic view of a sealing member for forming the bottom surface sealing part used in the manufacture of the self-supporting packaging bag SPB shown in FIG. 1. The sealing member shown in FIG. 9 is the same as the sealing member for forming the bottom surface part 41 of the above-described embodiment shown in FIG. 6. FIG. 10 shows a conventional sealing member for forming the bottom surface part 51, which is a sealing member according to the prior art, and is a schematic view of a sealing member for forming the bottom surface sealing part used in the manufacture of the conventional self-supporting packaging bag SPB-C shown in FIG. 12. As shown in Fig. 9, the seal member 41 for forming the bottom surface portion of the self-standing packaging bag SPB has a step cutout portion 42 at a position corresponding to a first step portion 31 based on the film overlap, which is at least the boundary between the two-layer portion TL of the pair of films 11 for forming the flat surface portion and the four-layer portion FL in which the film 12 for forming the bottom surface portion folded in two is sandwiched between the pair of films 11 for forming the flat surface portion. Further, when the cutout portion 13 is provided in the film 12 for forming the bottom surface portion, in the region where the film 12 for forming the bottom surface portion folded in two is sandwiched between the pair of films 11 for forming the flat surface portion, a side cutout portion 43 is provided at a position corresponding to a second step portion 32 based on the film overlap at the boundary between the two-layer portion TL corresponding to the cutout portions 13 at both ends of the film 12 for forming the bottom surface portion of the pair of films 11 for forming the flat surface portion and the four-layer portion FL other than the cutout portion 13 of the film 12 for forming the bottom surface portion. In Fig. 9, the side cutout portion 43 provided at the position corresponding to the second step portion 32 is formed integrally with the step cutout portion 42, but they may be formed independently.

[0069] In the present invention, the shape and the like of the step cutout portion 42 and the side cutout portion 43 of the seal member 41 for forming the bottom surface portion can be arbitrary shapes.

[0070] In the seal member 41 for forming the bottom surface portion according to the present invention, the size of the step cutout portion 42 for making the region including at least a part of the first step portion 31 into the unsealed portion 24a of the first step portion is not particularly limited. The step cutout portion 42 in the seal member 41 for forming the bottom surface portion shown in Fig. 9 is, for example, 80% or less, preferably 70% or less, more preferably 50% or less with respect to the width of one side seal portion 22, and for example, 5% or more, preferably 10% or more, more preferably 20% or more is preferably an unsealed portion 24a of the first step portion without being sealed.

[0071] In the bottom surface forming seal member 41 shown in Fig. 9, a side notch 43 for forming the unsealed portion 24b of the second step may be provided in the region including the second step 32. When the side notch 43 is provided, it is, for example, 100% or less, preferably 80% or less, more preferably 70% or less, still more preferably 50% or less with respect to the total length of the second step 32, and, for example, 0% or more, preferably 5% or more, more preferably 10% or more, still more preferably 20% or more is not sealed and becomes the unsealed portion 24b of the second step.

[0072] In the present invention, the material constituting the bottom surface forming seal member 41 is not particularly limited as long as it is a material capable of forming a seal by heating and pressing the heat fusion layer. For example, metals such as iron, stainless steel, aluminum, and aluminum alloys, ceramics, mixtures thereof, combinations thereof, etc. may be mentioned.

[0073] Note that the bottom surface forming seal member 41 for the self-standing packaging bag shown in Figs. 6 and 9 is used for manufacturing one bag at a time. However, as shown in Fig. 11 for example, the bottom surface forming seal member may be formed so that two bags can be manufactured by one seal, or a plurality of bags more than that can be manufactured.

[0074] As described above, the present invention has been described using the above embodiments. However, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various changes or improvements can be made to the above embodiments without departing from the gist of the invention, and the forms with such changes or improvements are also included in the technical scope of the present invention. Also, the above embodiments may be combined as appropriate. In particular, although the manufacturing method of the self-standing packaging bag using a film containing a polyester resin in the heat fusion layer has been described, the heat fusion layer of the film does not have to contain a polyester resin.

Explanation of Signs

[0075] SPB Self-standing packaging bag SPB-C Conventional self-standing packaging bag Ap Upper opening 11 Flat part / Film for forming flat part 12 Bottom part / Film for forming bottom part 13 Cut-off part 14 Fold line of film for forming bottom part 15 Planned cutting line 16 Boundary line of side seal part 21 Bottom surface seal part 21a Lower end seal 21b Bottom surface shape forming seal 21ba Diagonal seal 21bb Arc-shaped seal 21C Conventional bottom surface seal part 22 Side seal part 23 Step part special seal part 24a First step part unsealed part 24b Second step part unsealed part 25 Bottom surface unsealed part 26 Conventional bottom surface unsealed part 31 First step part 32 Second step part TL 2-layer part FL 4-layer part 41 Seal member for forming bottom part 42 Notch part of step part 43 Notch part of side part 44 Bottom surface shape forming seal forming part 44a Diagonal seal forming part 44b Arc-shaped seal forming part 45 Lower end seal forming part d Width dimension 51 Conventional seal member for forming bottom part 52 Conventional bottom surface notch part

Claims

1. A method for producing a self-supporting packaging bag which is composed of a pair of flat sections and a bottom section folded in half into an inverted V-shape at the bottom, has a side seal section and a bottom seal section, and has a step section based on a film overlap between a two-layer section where the pair of flat sections overlap and a four-layer section where the pair of flat sections and the bottom section overlap, In a first sealing step, a region including at least a part of the step portion is heated and pressurized while remaining an unsealed portion, and then cooled to form the bottom surface seal portion, and the unsealed portion is sealed by heating, pressurizing, and cooling in a second sealing step or later. A method for manufacturing the self-standing packaging bag.

2. The method for producing a self-supporting packaging bag according to claim 1 , wherein the pair of planar portions and the bottom portion are made of a film having a heat-sealing layer containing a polyester-based resin.

3. A sealing member used in a method for producing a self-supporting packaging bag, the self-supporting packaging bag being composed of a pair of flat surfaces and a bottom surface folded in half into an inverted V-shape at the bottom, having a side seal and a bottom seal, and having a step portion based on a film overlap between a two-layer portion where the pair of flat surfaces overlap and a four-layer portion where the pair of flat surfaces overlap the bottom surface, In the first sealing step, the heat sealing mold is used to form the bottom surface seal portion, which has an area including at least a part of the step portion as an unsealed portion. The sealing member.

4. A self-supporting packaging bag manufactured by the manufacturing method of claim 1 or 2.

5. The film is made up of a pair of flat surfaces and a bottom surface folded in half in an inverted V shape at the bottom, has a side seal and a bottom seal, and has a step portion based on the overlap of a film between a two-layer portion where the pair of flat surfaces overlap and a four-layer portion where the pair of flat surfaces overlap the bottom surface, A method for producing a self-supporting packaging bag using a bag making machine having a plurality of sets of sealing jigs that are cooled after heating and pressurizing, The step portion has an area that is sealed only by the last set of sealing jigs. A method for manufacturing the self-standing packaging bag.

Images