JPH05221453A - Easily openable packaging bag - Google Patents

Abstract

PURPOSE:To unpack a packaging bag easily and smoothly, no matter in which direction an external force is being applied. CONSTITUTION:The easy open packaging bag is formed of a laminated film 4 consisting of a biaxially oriented layer 1 and a sealant layer 3 formed thereon by heat sealing the sealant layer 3 with a plurality of tear guiding mars 8 formed in at least one heat sealing part 7 extending in the edge overlapping direction at intervals. The angles alpha1 and alpha2 at which the molecular orientation lines 9 and 10 of the biaxially oriented film 1 and the side edge of the heat sealing part 7 having the tear guiding mars formed thereon of the packaging bag intersect are to be not more than 15 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-open packaging bag suitable for packaging liquids, viscous substances, and the like, and particularly to the bowing phenomenon that occurs in the production of biaxially stretched films ( For example, the influence of JP-B-37-1588 and JP-A-54-73873) can be advantageously reduced to make it extremely easy to open the packaging bag.

[0002]

2. Description of the Related Art Conventionally known easy-open packaging bags include those disclosed in JP-A-61-60469 and JP-A-61-142159. The packaging bag described in these is a packaging bag formed by heat-sealing at least three sides, and is provided at the fusion-bonded portion or the outer portion thereof on the edge and / or somewhat inward of the missing portion. With a plurality of flaws or through holes that are not provided, such an easily-openable packaging bag can cut the bag from any position of the fusion-bonded portion by the force of fingers, and further, the strength of the film can be improved. It is said that foreign matter will not be mixed in during processing without damage.

[0003]

By the way, the biaxially stretched film as the base film of the film laminated structure is
In many cases, due to the bowing phenomenon at the time of manufacture, the anisotropy of the molecular orientation direction is anisotropy between the central portion and the side edge portions in the width direction, as shown in FIG. In particular, when it is used by cutting the side end portion of the biaxially stretched film at the time of production as shown by the broken line in the drawing, the biaxially stretched film layer and the sealant layer are used. The film laminated structure comprising, for example, by folding in two in the width direction to form a bag, the molecular orientation direction of the biaxially stretched film layer, on the surface side of the bag,
On the back side of the bag, as shown by the thin line in Fig. 4, on the back side of the bag, this is also a curve with a relatively large slope to the right, as shown by the dashed line in the figure. , Therefore, as in the prior art, a plurality of solid defects, for example in the longitudinal sealing part of the heat-sealed part shown by hatching in the figure, located on its edges and / or somewhat inwards. Even if it is possible to start tearing the bag at any position of the vertical seal portion by simply providing the through hole, the tear can be smoothly advanced under the action of a small tearing force. In some cases, it became very difficult to open the bag.

That is, when the bag is opened, the direction of the external force acting on the bag is, as shown in FIG. 4 (a), the direction of tearing, and the molecular orientation lines of the biaxially stretched films on the front and back surfaces cross each other. Direction, that is, if the back side orientation line indicated by the one-dot chain line is pulled to the front side, and the front side orientation line indicated by the thin line is pulled to the back side, respectively, it is positioned between the front and back biaxially stretched film layers. Since the sealant layer to be subjected to external force in the direction of being sheared by the molecular orientation lines on the front and back, the sealant layer is relatively easily cut without being influenced by the molecular orientation direction, in other words, the bag under the action of a small external force. On the other hand, the action direction of the external force is the direction in which the molecular orientation lines on the front and back surfaces are separated from each other, as shown in Fig. 4 (b), and the back side orientation line indicated by the one-dot chain line is shown. To the back side, When the surface-side orientation lines indicated by the lines are respectively pulled to the front side, the sealant layer between the biaxially stretched film layers receives an external force in the direction of peeling from the biaxially stretched film layer, and the sealant Since the layer is greatly stretched and deformed, there is a problem that the tear resistance of the bag is significantly increased and a considerably large force is required to open the bag.

By the way, in the film laminated structure, the thickness of the biaxially stretched nylon film layer is 15 μm, the thickness of the polyethylene layer as the sealant layer is 50 μm, and the angle of intersection of the molecular orientation lines with the widthwise edges of the packaging bag is about 30. In terms of degrees, when an external force is applied in the direction shown in FIG. 4 (a), a force of about 160 g is applied, and when an external force is applied in the direction shown in FIG. 4 (b), a force of 2000 g or more is applied. Against the action of tensile force in the directions shown in FIGS. 4 (c) and 4 (d), the packaging bag was opened with a force of 2000 g or more and about 150 g, respectively.

The present invention advantageously solves the above problems of the prior art by allowing the initiation of tearing of the bag at any location of at least one heat-sealed portion sufficiently easy to proceed. As a result, there is provided an easy-open packaging bag that can always open the packaging bag regardless of the action direction of the external tearing force.

[0007]

According to various tests, the easy-open packaging bag of the present invention has a relative relationship between the molecular orientation direction of the biaxially stretched film layer and the tear resistance of the packaging bag, and If the angle of intersection between the tearing direction of the packaging bag and the molecular orientation line is within a certain range, the required tearing force should be sufficiently small regardless of the direction of the external force acting on the packaging bag. It was made as a result of the finding, a biaxially stretched film layer, and a film laminated structure comprising a sealant layer laminated on the biaxially stretched film layer, formed into a bag by heat sealing the sealant layer, at least In one heat-sealed portion, in a packaging bag having a plurality of tear-inducing flaws located at intervals in the extending direction thereof, the molecular orientation line of the biaxially stretched film layer, and the tear-inducing of the packaging bag. The edge of the heat-sealed portion which is provided, or is it to those with less than 15 degrees crossing angle between the parallel edges.

[0008]

In this easy-to-open packaging bag, the heat-sealed portion is specified by specifying the extending direction of the molecular orientation line of the biaxially stretched film layer and bringing it close enough in the direction orthogonal to the direction of tearing. The tearing of the packaging bag can be easily started from the arbitrary position of the heat-sealed portion under the action of a plurality of tearing-induced flaws provided on the sheet, and the progress of the tearing depends on the action direction of the external force. Regardless of
It will always be smooth and easy.

In other words, when the acting direction of the external tearing force is the direction in which the molecular orientation lines of the biaxially stretched film layers on the front and back surfaces cross each other, as shown in FIG. The initiation of the tearing is carried out with a sufficiently small force in the same manner as described above, and the action direction of the external force is as shown in Fig. 4 (c). When the orientation lines are in directions away from each other, tearing of the packaging bag is similar to that described above, in the sealant layer between the biaxially stretched film layers, in the direction in which it is torn from the biaxially stretched film layers. However, the biaxially stretched film layers on the front and back surfaces are torn from the directions substantially orthogonal to the respective molecular orientation directions, and the biaxially stretched film layers are bilaterally stretched. Based on the fact that tearing progresses almost at the same time, the tearing of the sealant layer that receives an external force in the peeling direction also progresses along with the tearing of both biaxially stretched film layers, and the external force acting on the sealant layer hardly causes its elongation deformation. Therefore, the tear resistance of the sealant layer is sufficiently reduced, and the tearing force required to start tearing of the packaging bag can be significantly reduced as compared with the prior art.

By the way, the tearing of the sealant layer thus generated in the heat-sealed portion is caused under the small tear propagation resistance of the sealant layer, in other words, the area other than the heat-sealed portion, in other words, the filling of the packaged object. Due to the easy propagation to the area, it is always easy to open the packaging bag, regardless of the direction of the external force acting on it.

As described above, when the biaxially stretched film layer is oriented in a direction perpendicular to the tearing proceeding direction at the time of tearing from the lateral seal portion of the packaging bag, the molecular orientation direction thereof is When the packaging bag is torn from its longitudinally sealed portion, the molecular orientation lines are close to the direction of the tearing, and at this time also, the biaxial stretching due to the action of the external tearing force on the packaging bag. The tear resistance of the film layer itself is very small regardless of the direction of action of the external force.

That is, in this case, the biaxially stretched film layer tears in a direction substantially along the molecular orientation line, so that the acting direction of the external force is as shown in FIG. 4 (a). Not only when the alignment lines are in the crossing direction, but also when the molecular alignment lines are in the directions separating from each other as shown in FIG. 4 (b), the volume of the sealant layer which receives the external force in the peeling direction, In other words, since the adhesive area of the sealant layer to the biaxially stretched film becomes small, the tear resistance of the sealant layer can be greatly reduced, and the required tear force of the packaging bag can be made sufficiently small.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a diagram showing an embodiment of the present invention.
(a) is a plan view of an easy-open packaging bag formed by sealing a film laminated structure on three sides, FIG. 1 (b) is a plan view of the film laminated structure, and FIG. 1 (c) is c of FIG. 1 (b). It is sectional drawing which follows the c line.

In this example, a biaxially stretched film layer as the base material, for example a biaxially stretched nylon film layer 1
To form a film laminated structure 4 by sequentially laminating a polyethylene layer 2 as an intermediate layer and an ethylene-vinyl acetate copolymer layer 3 as an example of a sealant layer. From the center of the, as shown by arrow A in Fig. 1 (c),
As shown in FIG. 1 (a), the ethylene-vinyl acetate copolymer layers 3 are folded back in the directions opposite to each other, and in this state, the ethylene-vinyl acetate copolymer layers 3 are heat-sealed to form a bag. Then, the packaging bag 5 heat-sealed in three directions is formed.

The packaging bag 5 has a U-shaped heat-sealing portion 6 as shown by hatching in the figure, and the length of the lateral-sealing portion 7 as one sealing portion of the heat-sealing portion 6 is increased. It has a plurality of tear guide flaws 8 provided at intervals in the depth direction.

Here, the one tear guide flaw 8 has a single flaw extending in a negative shape in the width direction of the lateral seal portion 7 and a perforation in the width direction, as shown in FIG. 1 (a). ), A plurality of flaws such as a plurality of flaws having a small hole shape provided at intervals in the width direction of the lateral seal portion 7 as shown in FIG. The depth of each tear guide flaw 8, the widthwise length of the lateral seal portion 7, the spacing between the tear guide flaws 8 in the longitudinal direction of the lateral seal portion 7, and other dimensions are the thickness of the film laminated structure 4. Now, it can be appropriately selected depending on the constituent material of the laminated structure 4.

It should be noted that each of the tearing-induced flaws 8 can extend all or every other one up to the edge position of the transverse seal portion 7, and all of them can be extended.
It can also be formed with some separation from the edge position of the lateral seal portion 7.

By the way, especially in the case of such a vertical seal for the packaging bag 5, it is not always necessary to apply it to the side edge position of the bag, and the outer edge of the vertical seal portion formed by the vertical seal is set to the side of the bag. It is also possible to position it somewhat inward of the edge position, which can effectively prevent the sealant material from protruding outside the bag at the time of vertical sealing.

In such a packaging bag 5, here,
Surface side biaxially stretched nylon film layer 1 shown by thin lines in the figure
And the molecular orientation line 9 of the back side biaxially stretched nylon film layer 1 shown by the dashed line in the figure with the edge of the width direction of the packaging bag 5 at 15 degrees or less, preferably 7
And be extended in a direction intersecting degrees in the following crossing angle alpha _1, alpha _2, which is therefore, also extending direction of molecular orientation line 11 of the film laminate structure 4 shown in FIG. 1 (b), the upper edge Alternatively, the angle of intersection with the lower edge is 15 degrees or less, preferably 7 degrees or less.

In this packaging bag 5, the angle of intersection of the molecular orientation lines 9 and 10 with the lengthwise edges is 15
It is possible to make it less than or equal to 4 degrees, and even in this case,
As shown in FIGS. 4 (a) and 4 (d), the action direction of the external force of tearing on the packaging bag 5 is such that the molecular orientation lines 9 and 10 of the biaxially stretched nylon film layer 1 on the front and back surfaces cross each other. Of course, as shown in FIGS. 4 (b) and 4 (c), when the molecular alignment lines 9 and 10 are in directions in which they are separated from each other, the required tearing force can be reduced as compared with the conventional technique. It can be significantly reduced.

Here, the tearing-inducing flaw 8 of the packaging bag 5 as described above can be formed after the heat sealing of the film laminated structure 4 is completed, or can be formed on the film laminated structure 4 before the heat sealing. In the latter case, in particular, in the latter case, the tearing guide flaws 8 can be wound, unwound, etc. by arranging each of the tearing guide flaws 8 at some distance from the side edge position of the film laminate structure 4. It is possible to effectively prevent accidental breakage during the process.

Further, it is not always necessary to penetrate the tear guiding flaw 8 on both the front and back surfaces of the packaging bag 5, and the tear guiding flaw 8 may be provided on only one of the front and back surfaces.

FIG. 2 is a graph showing the tearing force required to open the packaging bag. The film laminated structure comprises a biaxially stretched nylon film layer having a thickness of 15 μm and a polyethylene layer having a thickness of 50 μm. In the packaging bag, while changing the crossing angle of the molecular orientation line with respect to the widthwise edge of the packaging bag from 1 degree to 20 degrees, the action direction of the external tearing force on the packaging bag is shown in Figs. 4 (a) to (d). The required tearing force of each bag when changed as shown is as illustrated.

That is, when the packaging bag is torn from the lateral seal portion of the packaging bag, the direction of the external force of tearing is such that the molecular orientation lines cross each other as shown in FIG. 4 (d). As shown by the triangle in the figure, the tearing force of the packaging bag is always a value within the range of 150 to 160 g, regardless of the size of the intersection angle of the molecular orientation line with the widthwise edge of the packaging bag. , When the acting direction of the external force is the direction in which the molecular orientation lines are separated from each other as shown in Fig. 4 (c), the required tearing force is the increase of the crossing angle, as shown by the cross mark in the figure. It gradually increases, and this increasing tendency becomes particularly remarkable when it exceeds 15 degrees, and when it exceeds 15 degrees, the required tearing force of the packaging bag is up to 300 g, which is a value that is perceptually easy to tear. It will exceed the value.

Therefore, here, the crossing angle of the widthwise edge of the packaging bag, in other words, the edge having the tearing-inducing flaw is 15
The required tearing force of the packaging bag is ensured to be sufficiently reduced by setting the tearing force to 7 degrees or less, preferably 7 degrees or less so that the required tearing forces are substantially the same regardless of the acting direction of the external force.

Incidentally, in the graph,
If the bag cannot be torn even if the tearing force exceeds 500 g, the bag can be opened only by breaking the polyethylene layer with a force exceeding 2000 g.

Further, when the packaging bag is torn from the longitudinal sealing portion of the packaging bag with the molecular orientation direction of the biaxially stretched film layer kept as described above, the acting direction of the external force is
As shown in Fig. 4 (a), when the molecular orientation lines cross each other, the tearing force of the packaging bag is as shown in Fig. 4 (d), as is clear from the black circles in the figure. Similar to the above, the value is within the range of 150 to 160 g regardless of the magnitude of the crossing angle, while the action direction of the external force of tearing is the direction in which the molecular orientation lines are separated from each other, as shown in Fig. 4 (b). The tearing force at this time has the same value as that shown in FIG. 4 (c), as shown by the white circle in the figure.

Therefore, according to this graph, the crossing angle between the molecular orientation line of the biaxially stretched film layer and the widthwise side edge of the packaging bag is set to 15 degrees or less, so that the packaging bag is pulled from the lateral seal portion. It is understood that the required tearing force can be made sufficiently small regardless of the acting direction of the external tearing force in both cases of tearing and tearing from the longitudinal seal portion.

By the way, the above-mentioned tearing force of the packaging bag is formed by the film laminated structure including the biaxially stretched nylon film layer 1, the polyethylene layer 2 and the ethylene-vinyl acetate copolymer layer 3 as shown in FIG. The same applies to the case where the heat seal portion 6 is used.
After the smooth tearing of the packaging bag 5 is started once with the small required tearing force as described above, even if the tear propagates to the filling region of the packaged object, the polyethylene layer 2 and Due to the small tear propagation resistance of the ethylene-vinyl acetate copolymer layer 3, the tearing of the packaging bag 5 can be continued with a sufficiently small force, so that the packaging bag 5 is small regardless of the acting direction of the external tearing force. It will be opened easily and smoothly by force.

In the above-mentioned place, the tear guide flaw 8 provided on the packaging bag 5 functions to give a trigger for opening the packaging bag 5 from an arbitrary position of the heat seal portion 6,
The tearing of the bag 5 at the tearing-induced flaw portion is performed with a force much smaller than the required tearing force described above, regardless of the acting direction of the force.

The present invention has been described above based on the illustrated examples, but the heat-sealing form of the packaging bag can be appropriately selected from various known ones such as a four-sided seal and the like, as required.

[0032]

As described above, according to the present invention, it is possible to sufficiently guide the opening of a packaging bag from an arbitrary position with a tear guide flaw under the action of a small force, and the tear guide flaw is provided. The edge of the heat-sealed portion, or, by setting the angle of intersection of the molecular orientation line with the edge parallel to it to a value within the range of 15 degrees or less, in particular, of the biaxially stretched film layer on the front surface side and the back surface side, It is possible to significantly reduce the required tearing force when a tearing external force is applied in the direction of separating the molecular orientation lines on each surface, and therefore, regardless of the direction of the action of the tearing external force on the packaging bag, The opening of the packaging bag can be made extremely easy and smooth.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a required tearing force and a crossing angle of a molecular orientation line with respect to a widthwise edge of a packaging bag.

FIG. 3 is a diagram illustrating anisotropy of molecular orientation of the produced biaxially stretched film.

FIG. 4 is a diagram showing an opening mode of a packaging bag.

[Explanation of symbols]

 1 Biaxially Stretched Nylon Film Layer 2 Polyethylene Layer 3 Ethylene-Vinyl Acetate Copolymer Layer 4 Film Laminated Structure 5 Packaging Bag 6 Heat Sealing Part 7 Vertical Sealing Part 8 Tear Inducing Defects 9,10 Molecular Orientation Line

Claims (1)

[Claims] 1. A film laminated structure comprising a biaxially stretched film layer and a sealant layer laminated on the biaxially stretched film layer is formed into a bag by heat-sealing the sealant layer, and at least one heat-sealing portion. In, a packaging bag having a plurality of tear-induced flaws located at intervals in the extending direction, the molecular orientation line of the biaxially stretched film layer, the packaging bag, the heat provided with the tear-induced flaws. An easy-open packaging bag that has an angle of 15 degrees or less with the edge of the seal part or the edge parallel to it.