JP2009196654A - Self-standing bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-standing bag having a basic function as a packaging body prevented from being lowered, having a bottom part film capable of being easily developed, and is excellent in filling performance of contents. <P>SOLUTION: The self-standing bag 10 includes a pair of wall face films 11 both side edge parts of which are joined and forms two faces of a surface and a back face, and a bottom part film 12 which is prepared by folded back the films in a mountain folding way toward the upper part side of the bag, inserting them into the lower parts of both wall face films 11 and joining the peripheral edge parts to the lower part of both wall face films 11, and the bottom part film 12 includes heat-shrinkable properties. The bottom part film 12 is equipped with a heat-shrinkable film layer 15, and the heat-shrinkable film layer 15 is provided on the undersurface of the bottom part film 12. Practically, the heat-shrinkable film layer 15 is a central part of the bag bottom part 14 of the bottom part film 12, and includes a mountain folding part 13, and is provided at a part along the ridge skirt direction of both sides of it. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a self-supporting bag, and more particularly to a self-supporting bag excellent in the filling property of contents that are suitable for a package such as food.

  A self-supporting bag is also called a standing pouch, and is a bag (pouch) that is provided with a town at the bottom of the bag to provide self-supporting properties. This town is called a bottom gusset, and is formed by a bottom film having a mountain fold portion that is folded back into a mountain fold toward the upper side of the bag. Due to the function of this bottom gusset, the self-standing bag has the effect of reducing the transportation cost because the volume is small and not bulky before filling the contents and after taking out the contents. It is a bag having effects such as excellent display properties and display properties.

  Since the self-supporting bag has excellent characteristics as described above, it is widely used as a package for various products such as liquid beverages, jelly beverages, kneaded products, and pharmaceuticals. When these foods or the like are used as contents, the contents are generally filled in a bag with heat-sterilized contents in order to prevent the contents from being spoiled or deteriorated. In addition, the film constituting the self-supporting bag is required to have not only impact resistance and wear resistance, but also physical properties such as heat resistance and gas barrier properties.

  As a method for filling the contents into the self-supporting bag, for example, a method of filling the contents from the upper part of the bag using an automatic filling device capable of high-speed filling is adopted. When the self-supporting bag is filled with the contents from the top of the bag, the mountain folds of the bottom film develop as the pair of wall surface films forming the front and back surfaces of the bag are separated from each other, thereby expressing self-supporting properties. As shown in FIG. 6, the mountain fold portion of the bottom film may not develop well due to close contact with the wall surface film. FIG. 6 is a schematic diagram showing a cross-section of a main part of a conventional free-standing bag filled with contents. If the bottom film does not develop well, the content will be insufficiently filled or the filling amount will vary. Furthermore, the independence of the bag becomes insufficient, causing problems such as being easy to collapse or not being independent.

  In view of such a situation, several self-supporting bags have been developed in which the bottom film can be easily opened to improve the filling performance of the contents. For example, Patent Document 1 discloses a self-supporting bag characterized in that the bottom film of the self-supporting bag is formed of a laminated film formed by coextrusion including at least a polyamide layer, a sealan, and a linear low-density polyerylene layer as a layer. Is disclosed. According to Patent Document 1, it is preferable that the bottom film has flexibility rather than rigidity, and the wall film and the bottom film are made of different resin materials.

JP 2007-246157 A

  However, since the bottom film is a member constituting the outer shape of the self-supporting bag, like the wall film, it is not preferable that the basic performance such as wear resistance, heat resistance, gas barrier properties, and the like is deteriorated. According to the self-supporting bag of Patent Document 1, when the flexibility of the bottom film is increased, the filling performance of the contents is improved, but the performance such as wear resistance, heat resistance, gas barrier properties, and the like is lowered. On the other hand, if the basic performance of the bag is to be maintained, the rigidity of the bottom film increases and the filling performance decreases. Therefore, in the self-supporting bag of Patent Document 1, it is difficult in principle to adjust both performances and to achieve a high degree of compatibility.

  The object of the present invention is to provide a self-supporting material that does not deteriorate the basic performance of the package, such as wear resistance, heat resistance, and gas barrier properties, and that the bottom film can be easily developed and has excellent filling performance for contents. Is to provide a bag.

  The self-supporting bag according to the present invention has a pair of wall surface films whose side edges are joined to form two front and back surfaces, and folded into a mountain fold toward the upper side of the bag and inserted into the lower portions of the both wall surface films. A self-supporting bag having a bottom film having a peripheral edge joined to a lower part of the film, wherein the bottom film includes a heat-shrinkable film layer.

  Moreover, it is preferable that a heat-shrinkable film layer is provided in the lower surface of a bottom part film.

  According to the self-supporting bag of the present invention, since the bottom film has heat shrinkability, when the heat-sterilized contents are filled, the bottom film is heated and contracted by the heat of the contents, so that the bottom film The development of the film becomes easy. The self-supporting bag according to the present invention is such that the mountain fold portion of the bottom film spreads and becomes self-supporting by filling the contents, but the heat shrink function of the bottom film compensates for the spread of the mountain fold portion of the bottom film. Is done. When the bottom film contracts, the mountain fold portion of the bottom film receives a force toward the lower direction of the bag, that is, the direction in which the bottom film develops.

  The self-supporting bag according to the present invention employs a bottom film unfolding mechanism that is completely different from the conventional self-supporting bag that facilitates opening of the bottom film and improves the filling performance of the contents. Therefore, the basic film performance such as wear resistance, heat resistance and gas barrier properties is not deteriorated, and the bottom film can be easily developed, and the self-supporting bag is excellent in filling performance of contents.

  In the invention described in claim 2, since the heat-shrinkable film layer is provided on the lower surface of the bottom film, the development of the bottom film is further facilitated. For example, it is not necessary to consider the effects on the contents due to delamination, etc., compared to the case where a heat-shrinkable film layer is provided on the top surface of the bottom film, so the heat-shrinkable film layer has a higher heat shrinkage rate It becomes possible to do. Therefore, the mountain fold portion of the bottom film is easily subjected to a force toward the lower portion of the bag, and further, the development of the bottom film is facilitated.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a self-supporting bag in which a heat-shrinkable film layer is provided on the bottom surface of the bottom film. FIG. 2 is a diagram illustrating a state in which the contents are filled in the self-supporting bag of FIG. FIG. 3 is a schematic view showing a cross section of the main part of FIG. FIG. 4 is a schematic view showing a state in which a laminated film having a heat-shrinkable film layer as the bottom layer is applied as the bottom film in FIG.

  As described above, the self-supporting bag 10 is also referred to as a standing pouch, and is a bag (pouch) that is provided with a town called a bottom gusset at the bottom of the bag so as to be self-supporting when the contents are filled. As shown in FIGS. 1 and 3, the self-supporting bag 10 has a structure in which a bottom film 12 is inserted at the bottom of a pair of wall surface films 11 constituting the front and back surfaces by being folded back and inserted toward the inside of the bag. It is composed of The bottom film 12 is a member that constitutes the bottom surface of the bag and fulfills the function of a town called a bottom gusset.

  As shown in FIG. 3, the self-supporting bag 10 is in a compressed state before the contents are filled because the bottom film 12 is folded back in a mountain-fold toward the inside of the bag. On the other hand, when the contents are filled, the bottom film 12 is self-supporting by developing. Therefore, the self-supporting bag 10 has an effect of reducing the transportation cost because the volume is small and not bulky before filling the contents and after taking out the contents. It is a bag having effects such as excellent.

  As shown in FIGS. 1 and 2, a spout 16 is attached to the self-supporting bag 10. The spout 16 is provided to communicate the inside and the outside of the self-supporting bag 10. The spout 16 has a cylindrical body portion and a shape having a through hole therein, and the contents are taken out through the through hole. Further, as will be described later, the contents are filled through the spout 16. In the following description, the self-supporting bag 10 has the spout 16 and the contents are filled through the spout 16. However, the self-supporting bag 10 is not limited to this, and is a bag without the spout 16 attached. Also good.

  The wall film 11 is a film constituting the front and back surfaces of the self-supporting bag 10. As shown in FIG. 1, the bag surface is a body portion of the self-supporting bag 10, and two surface surfaces of the self-supporting bag 10 are formed by two wall films 11. The wall film 11 can be formed by folding a single film, but is preferably formed of two films from the viewpoint of improving productivity.

  The two wall films 11 provided opposite to each other have an upper portion and both side edges integrally joined. The spout 16 is attached to the upper joint as described above. Both side edges are joined from the upper end to the lower end of the self-supporting bag 10. Here, the method for joining the films is not particularly limited, but is preferably performed by heat sealing from the viewpoint of improving productivity and reducing environmental burden.

  The wall film 11 constituting the body portion of the self-supporting bag 10 is required to have basic performance as a packaging body such as impact resistance, wear resistance, heat resistance and gas barrier properties as well as self-supporting properties. Therefore, it is preferable to be made of a material excellent in rigidity and shape retention. Therefore, as the film constituting the wall film 11, a single layer film can be used, but a laminated film is preferably used. In general, a laminated film includes a base film layer and a sealant layer, and the base film layer is provided on the outer side.

  Examples of the film constituting the base film layer include polyester (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycarbonate (PC), etc.), polyolefin (polyethylene (PE), polypropylene ( PP), etc.), polyamide (nylon-6, nylon-66, etc.), polyacrylonitrile (PAN), polyimide (PI), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polymethyl methacrylate (PMMA), poly A stretched or unstretched film of one layer or two or more layers composed of ether sulfone (PES) and ethylene-vinyl alcohol copolymer (EVOH) can be used.

  The films constituting the sealant layer include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene-propylene copolymer (EP), unstretched polypropylene (CPP), and ethylene-α olefin copolymer. It is possible to use a film of one layer or two or more layers composed of ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-vinyl acetate copolymer (EVA) and the like. it can.

  As a method for laminating the films constituting the base film layer and the sealant layer, known laminating methods such as a dry lamination method and a hot melt lamination method can be used. The laminated film can also be produced by coextrusion using the above resin material.

  When the content is food or the like, the film constituting the wall film 11 preferably has gas barrier properties. Therefore, in order to improve the gas barrier property of the film, a metal thin film such as aluminum, or a resin film such as polyvinylidene chloride (PVDC) or ethylene-vinyl alcohol copolymer (EVOH), or an arbitrary synthetic resin film, such as aluminum oxide or A transparent deposited film on which an inorganic oxide such as silica is deposited can also be provided. This gas barrier layer can be provided, for example, between the base film layer and the sealant layer. Further, if necessary, an adhesive layer can be provided between the gas barrier layer and the base film layer.

  The wall surface film 11 can be provided with a printing layer such as a product name, a product image, or a design (not shown) indicating the quality of the product on the surface, that is, the front and back surfaces of the self-supporting bag 10. Specifically, for example, it is provided on the back surface of the outermost layer among the base film layers of the laminated film constituting the wall film 11.

  The bottom film 12 is a film that forms the bottom of the self-supporting bag 10. As shown in FIG. 3 and the like, the bottom film 12 is folded and inserted in a mountain fold toward the upper side of the bag, and the peripheral edge portion is integrally joined to the lower portion of the wall surface film 11. Therefore, as described above, the self-supporting bag 10 is in a compressed state before the contents are filled, and when the contents are filled, the bottom film 12 can be self-supported by unfolding. . That is, the bottom film 12 has not only a function of constituting the bottom surface of the freestanding bag 10 but also a function of changing the shape of the bag itself before and after filling the contents.

  As shown in FIGS. 1 and 3, the bottom film 12 has a mountain fold portion 13 that is folded back into a mountain fold, and a heat seal portion is formed in a bottom shape pattern at the bottom of both wall surface films 11. ing. In the state where the bottom film 12 shown in FIG. 1 is folded back into a mountain fold, the portion of the bottom film 12 excluding the heat seal portion has a bow shape. This bow-shaped portion is the bag bottom portion 14, and when deployed, it becomes a boat bottom shape as shown in FIG. 2 and constitutes the bottom surface of the self-supporting bag 10. As described above, the wall film 11 is composed of a laminated film excellent in rigidity and shape retention, but the joint between the bottom film 12 and both wall films 11 has particularly high rigidity. The self-supporting bag 10 can obtain stable self-supporting properties by using the joint portion having high rigidity as a leg. In addition, although the self-supporting bag 10 is demonstrated as what has the bow-shaped bag bottom part 14, as a shape of the bag bottom part 14, it is not limited to this, A well-known shape is applicable.

  The film constituting the bottom film 12 is required to have basic performance as a packaging body such as impact resistance, wear resistance, heat resistance and gas barrier property as well as the self-supporting property like the wall film 11. Therefore, it is preferable to be made of a material excellent in rigidity and shape retention. Therefore, it is preferable to use a laminated film of the same type as the wall film 11 as the film constituting the bottom film 12.

  The bottom film 12 includes a heat shrinkable film. By the heat shrink function of the bottom film, the spread of the mountain fold 13 of the bottom film 12 accompanying the filling of the contents is compensated. As the form of the bottom film 12 having heat shrinkability, when the bottom film 12 is a heat shrinkable film, the bottom film 12 is composed of a laminated film, and at least one film layer in the laminated film is a heat shrinkable film layer 15. Or the case where the heat-shrinkable film layer 15 independent of the constituent film is attached to the upper surface or the lower surface of the film constituting the bottom film 12. For example, as shown in FIGS. 1 and 3, the bottom film 12 is a central portion of the bag bottom portion 14, includes a mountain fold portion 13, and is provided with a heat-shrinkable film layer 15 along the mountain hem direction on both sides thereof. be able to. The heat-shrinkable film layer 15 has a function of facilitating the development of the bottom film 12 by a force generated with heat shrinkage. Here, the mountain fold portion 13 is included, and the mountain hem direction on both sides thereof means the lower portion direction of the bag, and the force generated with the heat shrinkage is the both sides of the mountain fold portion 13 and the mountain fold portion 13 of the bottom film 12. Will join. As will be described later, the force generated with the thermal contraction acts in the lower direction of the bag, that is, in the direction in which the bottom film 12 is developed.

  Of the forms of the bottom film 12 having heat shrinkability described above, a preferred form is a form in which the bottom film 12 has a heat shrinkable film layer 15, and more preferably, the heat shrinkable film layer 15 is the bottom film 12. It is a case where it is provided in the lower surface. As a method of providing the heat-shrinkable film layer 15 on the lower surface of the bottom film 12, as described above, a method of laminating as a film layer of a laminated film, or attaching a heat-shrinkable film layer as a film layer independent of the bottom film 12. The method of attaching is mentioned. As shown in FIG. 4, the self-supporting bag 10 to which the former method is applied has a heat-shrinkable film layer 15 over the entire area of the bottom film 12. In addition, when providing the heat-shrinkable film layer 15 by the latter method, the heat-shrinkable film layer 15 can be affixed using an adhesive agent or an adhesive. When the heat-shrinkable film layer 15 is provided as a layer of the laminated film constituting the bottom film 12, the difference in bonding strength between layers and the heat shrinkage rate is reduced so that the interlayer strength with other film layers does not decrease. It is necessary to set the heat shrinkage rate with sufficient consideration. On the other hand, when it is provided on the lower surface of the bottom film 12 independently from the bottom film 12, even if the interlayer strength is lowered, there is no influence on the structural strength of the self-supporting bag 10, and the heat shrinkage rate is set higher. Is possible. Therefore, the mountain folds 13 and the like of the bottom film 12 are easily subjected to a force generated as the heat-shrinkable film layer 15 contracts, and the bottom film 12 can be easily deployed.

  The heat-shrinkable film layer 15 is preferably provided over a wide area on the bag bottom 14 of the bottom film 12 in order to further facilitate the developability of the bottom film 12. In particular, it is preferable to include a large number of mountain folds 13. The area on which the heat-shrinkable film layer 15 is provided is preferably 30% to 100%, more preferably 50% to 90% of the bag bottom 14. When the area of the heat-shrinkable film layer 15 is within this range, the production of the self-supporting bag 10 is easy, and the development of the bottom film 12 becomes good.

  Examples of the resin constituting the heat-shrinkable film layer 15 include polyester resins (polyethylene terephthalate, etc.), polyolefin resins (polyethylene, polypropylene, etc.), polystyrene, polyvinyl chloride, and copolymers thereof (styrene-butadiene copolymer). Can be used.

  In order to develop good heat shrinkability, the heat shrinkable film layer 15 is preferably stretched. In the state in which the bottom film 12 shown in FIGS. 1 and 3 is folded, the heat shrinkable film layer 15 has a heat shrinkage rate in the direction along the mountain hem from the mountain fold 13, that is, the heat shrinkage rate in the vertical direction of the bag. It is preferably higher than the heat shrinkage rate in the direction along the mountain fold 13, that is, in the lateral direction of the bag. The stretch ratio is about 2 to 6 times in the lateral direction of the bag. On the other hand, it is preferably about 1.01 to 2 times. When the draw ratio is within this range, the thermal shrinkage rate in the lower direction of the bag, that is, the direction in which the bottom film 12 is developed increases, and the development of the bottom film 12 is improved.

  The heat-shrinkable film layer 15 is heated and shrunk by being filled with the heat-sterilized contents as shown in FIG. The heat-sterilized contents are filled in the self-supporting bag 10 from the spout 16 at a temperature of about 90 degrees. At this time, the bottom film 12 is first heated, and the temperature is transmitted to the heat-shrinkable film layer 15 provided on the lower surface, so that the heat-shrinkable film layer 15 is heated.

  The self-supporting bag 10 is manufactured by the following process, for example. First, a pair of wall films 11 in which both side edges of the two wall films 11 are heat-sealed are prepared, one end of the spout 16 is inserted into the upper part, and the body portion of the spout 16 and the pair of wall films 11 Heat seal the top. Next, the bottom film 12 folded back in a mountain fold is inserted into the lower part of the two wall film 11 on which the spout 16 is mounted, and the peripheral part of the bottom film 12 is heat-sealed with both wall films 11. When the heat-shrinkable film layer 15 is a film layer independent of the bottom film 12, the heat-shrinkable film layer 15 is applied to the lower surface of the bottom film 12 by applying an adhesive or a pressure-sensitive adhesive. The heat-shrinkable film layer 15 is preferably attached before the bottom film 12 is folded from the viewpoint of improving productivity. As described above, the self-supporting bag 10 shown in FIG. 1 can be manufactured.

  The operation of the self-supporting bag 10 having the above configuration will be described in detail below with reference to FIG. FIG. 5 is a diagram illustrating a state in which the bottom of the bag is unfolded when the contents are filled in FIG. 3, (a) shows a state in the middle of filling the contents, and (b) shows the contents completely. It is a figure which shows the state after being filled.

  The free-standing bag 10 spreads when the bottom film 12 is filled with the contents, so that the bag can stand on its own. Specifically, when the contents are filled, first, the two wall films 11 are separated. Next, the mountain fold part 13 of the bottom film 12 expand | deploys with the separation. The separation direction of the wall film 11 is the front and back direction formed by the wall film 11.

  Since the bottom film 12 is required to have basic performance as a packaging body such as impact resistance, abrasion resistance, heat resistance and gas barrier property as well as the self-supporting property, like the wall film 11. It is made of a material with excellent rigidity and shape retention. As shown in FIG. 6, the filling of the self-supporting bag 10 with the contents is performed through the spout 16. However, as shown in FIG. 6, the mountain fold 13 of the bottom film 12 is well developed by being in close contact with the wall film 12. May not. If the mountain fold part 13 does not expand well, the filling amount is insufficient or the filling amount varies. In addition, the bag is not self-supporting, causing problems such as being easily overturned or not self-supporting.

  When the content filled through the spout 16 is a food or the like, it is generally filled with heat sterilization. The heat-sterilized contents are filled in the self-supporting bag 10 from the spout 16 at a temperature of about 90 degrees. Accordingly, the self-supporting bag 10 is heated by filling the contents. As shown in FIG. 5, the heat-shrinkable film layer 15 is affixed to the lower surface of the bottom film 12 as a film layer independent of the film layer constituting the bottom film 12. Therefore, first, the bottom film 12 is heated, the temperature is transmitted to the heat-shrinkable film layer 15 provided on the lower surface, and the heat-shrinkable film layer 15 is heated.

  As described above, the self-standing bag 10 is such that the mountain fold 13 of the bottom film 12 is spread and self-supported by filling the contents, but the heat-shrinkable film layer 15 is filled with the contents. In this case, the bottom film 12 has a function of compensating for the spread of the mountain fold 13. That is, when the heat-shrinkable film layer 15 is heated and contracted by filling the contents, the mountain fold 13 of the bottom film 12 on which the heat-shrinkable film layer 15 is provided is in the lower direction of the bag, that is, the direction in which the bottom film 12 is unfolded. You will receive the power to go to. The heat shrinkable film layer 15 has a bottom portion so that the heat shrinkage rate in the vertical direction of the bag is higher than the heat shrinkage rate in the left and right direction of the bag when the bottom film 12 shown in FIGS. 1 and 3 is folded. Affixed to the lower surface of the film 12. Therefore, the amount of heat shrinkage in the vertical direction of the bag is large, and the force acting in the lower direction of the bag is large. In addition, as shown in FIG.5 (b), the self-supporting bag 10 obtains the stable self-supporting property by self-supporting by using the junction part of the rigid bottom film 12 and both the wall surface films 11 as a leg. be able to.

  The portion where the heat-shrinkable film layer 15 is provided is a central portion of the bag bottom portion 14 of the bottom film 12 and includes a mountain fold portion 13 and is a portion along the mountain hem direction on both sides thereof. The force generated by the shrinkage of the layer 15 toward the lower portion of the bag is applied to both sides including the mountain fold 13 of the bottom film 12. Therefore, the mountain fold 13 of the bottom film 12 is easily developed without being in close contact with the wall film 11.

  The function of the bottom film 12 to compensate for the expansion is expressed by the force toward the lower part of the bag generated by the shrinkage of the heat-shrinkable film layer 15. As shown in FIG. 5A, this force deforms the bag bottom 14 of the bottom film 12 folded back into a V shape into a U shape. And if the cross-sectional shape of the bag bottom part 14 becomes U-shaped, it becomes easy to apply the weight by filling of the contents evenly to the whole bag bottom part 14, and as shown in FIG. 13 can be developed without being in close contact with the wall film 11.

  The self-supporting bag 10 employs a deployment mechanism for the bottom film 12 that is completely different from the self-supporting bag that improves the filling performance of the contents by making the bottom film easy to open. Accordingly, the self-supporting bag 10 that is easy to unfold the bottom film 12 and has excellent filling performance of the contents without degrading the basic performance as a packaging body such as wear resistance, heat resistance, and gas barrier properties. Become.

It is a top view of the self-supporting bag in which the heat-shrinkable film layer in embodiment which concerns on this invention was provided in the lower surface of the bottom part film. It is a figure which shows the state with which the content was filled in the self-supporting bag of FIG. 1, and the upper edge part was joined. It is a schematic diagram which shows the principal part cross section of FIG. It is a schematic diagram which shows a mode that the laminated | multilayer film which has a heat-shrinkable film layer in the lowest layer as a bottom film in FIG. It is a figure which shows a mode that the bag bottom part at the time of being filled with the content in FIG. 3 expand | deploys, (a) shows the state in the middle of filling of the content, (b) after the content is completely filled It is a figure which shows the state of. It is a schematic diagram which shows the principal part cross section of the conventional self-supporting bag with which the content was filled.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Self-supporting bag, 11 Wall surface film, 12 Bottom film, 13 Mountain fold part, 14 Bag bottom part, 15 Heat-shrinkable film layer, 16 Spout.

Claims (2)

A pair of wall films that are joined on both side edges to form two front and back surfaces, and folded back into a mountain fold toward the top of the bag and inserted into the bottom of both wall films, and the peripheral edge is joined to the bottom of both wall films A free standing bag having a bottom film,
The bottom film is provided with a heat-shrinkable film layer. A self-supporting bag according to claim 1,
The heat-shrinkable film layer is provided on the lower surface of the bottom film.

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