JPH0735341U - Laminated film for packaging bag - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure the easy-opening property of the packaging bag and still accurately guide the traveling direction of the tear in the bag. [Structure] A laminated film comprising a base film layer 1 and a sealant layer 2, wherein the base film layer 1
At least one continuous groove 3 having a depth of not less than 50% and not more than 60% of its thickness is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to a laminated film suitable for use in the production of packaging bags, particularly easy-open packaging bags, and makes it easy to open the packaging bag, This is what makes it possible to identify such a situation.

[0002]

[Prior art]

 As a conventional technique proposed for facilitating the opening of the packaging bag, in addition to subjecting the peripheral portion of the packaging bag to processing such as so-called I-notch, V-cut and diamond-cut, Japanese Utility Model Publication No. 54-22484. JP-A-58-160251, JP-A-60-193843, JP-A-61-142159, JP-A-62-52065, JP-A-62-182067, JP-A-1111664. As disclosed in Japanese Patent Publication, etc., perform processing such as perforation holes, tear guide flaws, scratches on the film side edge surface, etc. on the packaging bag after bag making or before lamination. Is widely known, and it is recognized that these conventional techniques can facilitate the opening of the packaging bag.

[0003]

[Problems to be solved by the device]

 However, in all of these conventional techniques, notches, cuts, and holes are formed only in the portion that is heat-sealed by the laminated film bag-making or the portion that is separated from the storage space for the packaged object by the heat-sealing portion. However, since it is supposed to be subjected to processing such as scratches, when opening the packaging bag, it is relatively easy and smooth to start the opening by opening the processed portion. However, when the rip of the bag goes beyond the heat-sealed part to the space for containing the package, it is virtually impossible to orient the rip of the rip in the intended direction. Due to the molecular orientation of the stretched base film layer and other influences, the tearing of the bag progresses in an unintended direction, causing scattering, sagging, and spouting of the package It was often there.

The present invention advantageously solves the above-mentioned problems of the prior art, and in particular, by sufficiently reducing the influence of the molecular orientation of the stretched base film on the opening of the packaging bag, It is intended to provide a laminated film for a packaging bag, which can easily start the opening of the packaging bag and can guide the proceeding direction of tearing as expected.

[0005]

[Means for Solving the Problems]

 This invention relates to a laminated film including at least a base film layer made of a stretched plastic film and a sealant layer, and the base film layer has a depth of about 50% or more and 60% or less, preferably 100% or less. At least one continuous groove having a width of about 1000 μm is provided, for example, over the entire width of the laminated film, and ridges are formed on both sides of the continuous groove.

Here, it is preferable that the continuous strip groove be formed in line symmetry with respect to the center line in the width direction of the laminated film to be bag-manufactured in the two-fold posture in the width direction, and preferably, the continuous strip groove. The groove extends straight or curved.

Further, in another laminated film of the present invention, in particular, a groove having a depth shallower than the thickness of the base film layer is also provided, for example, in a perforated shape over the entire width of the laminated film, and each of them is formed. The ridges are formed on both sides of the groove.

[0008]

[Action]

 Such a laminated film for a packaging bag can be formed, for example, by irradiating a laser beam during slitting on a wide laminated film to continuously form a molten groove having a required depth in the required direction in the base film layer. Alternatively, it can be formed by forming it intermittently, and when this laminated film is used as a packaging bag of various known forms such as a three-sided seal type, a four-sided seal type, a pillow seal type, and a back seal type. The continuous groove or perforated groove formed by the laser beam extends at the required opening position of the packaging bag, for example, over the entire circumference of the front side portion and the back side portion. Then, it will be located exactly on both sides of the front and back.

Therefore, when opening the packaging bag for taking out the article to be packaged, it is sufficient to open the packaging bag from the position where the continuous groove extends or the groove where the perforation extends intermittently. Under the action of a small tearing force, the opening along the line groove position where the tearing resistance is low can be started easily and smoothly without providing notches, cuts, holes and flaws as in the prior art. Will be.

Then, the crevice of the bag formed by the start of such unsealing has a continuous groove or an intermittent groove to sufficiently remove the influence of the molecular orientation of the base film layer. Even if it reaches the storage space of the packaged product beyond the portion, the traveling direction is properly guided by the continuous groove or the intermittent groove formed on the front side and the back side of the packaging bag and overlapping with each other. Therefore, the rift will accurately follow the groove portion with small tear resistance and proceed.

Therefore, when opening the packaging bag, not only can the opening be performed with a small tearing force, but also the progression of the tear in the bag in an unintended direction is always sufficiently prevented, so that the packaged bag can be packaged. The risk of scattering, dripping, and spouting of objects is extremely effectively eliminated.

By the way, the effect of guiding the traveling direction of the sack of the bag in a required direction is particularly remarkable when the continuous groove or the intermittent groove is formed by irradiation of a laser beam. In this case, The melted base film forms ridges with high tear resistance on both sides of the groove, which prevents the crevice of the bag from escaping from the groove more effectively. become.

Here, when the continuous groove or the intermittent groove is formed symmetrically with respect to the center line in the width direction of the laminated film, a three-way or four-side seal bag-making process often performed by an automatic filling bag-making machine. In this case, it is possible to successfully superimpose the respective groove portions on the front side surface and the back surface side portion, and the groove groove allows the linear progression of the crevice of the bag to be extended by extending it linearly. By extending the curved lines, it is possible to smoothly guide the curved progress of the rupture of the bag.

When the groove is a continuous groove that guides the progress of the tearing of the bag as described above, the depth thereof is about 50% or more of the thickness of the base film layer. By setting the content to be not more than%, it is possible to secure the excellent tensile strength of the bag itself and still effectively reduce the tear resistance of the bag. Even when the groove is an intermittent groove, the depth of the groove is shallower than the thickness of the base film layer, which also contributes to the excellent tensile strength and tear resistance of the bag. Achieving both a sufficient reduction and a high level.

On the other hand, when the groove depth is made thicker than the thickness of the base film layer, the groove is also formed in the coating layer such as polyvinylidene chloride that may be provided on the inner surface side of the base film layer. Once formed, the packaging bag cannot be provided with the required gas barrier properties.

Further, in such a groove, it is more preferable that the width of the groove is about 100 to 1000 μm. That is, when heat-sealing a laminated film in a packaging bag, if the groove portion located on the front surface side and the groove portion located on the back surface side can always be accurately overlapped, Even if the groove width is about 30 to 50 μm, the progress of the tearing of the bag can be sufficiently effectively induced, but in reality, a single laminated film is folded back from, for example, the central portion in the width direction. It is difficult to accurately align the centerline positions of the respective groove portions extending to both the front and back sides of the bag due to the influence of folding error at the time of the stacking and the thermal strain of the laminated film during heat sealing. , Here, in consideration of the above influences in relation to the vertical and horizontal dimensions of the bag, even if they are affected by these influences, the minimum width of the groove is ensured in order to ensure the required overlapping width between the groove portions. To 100 μm .

On the other hand, it is empirically found that the deviation amount of the center line of the groove portion due to the above error, thermal strain, etc. is 1000 μm or more, and more accurately, the deviation amount reaches 950 to 970 μm. If there is almost no groove width and the groove width exceeds 1000 μm, if the center line positions of the groove portions on both sides of the bag happen to coincide, the bag will be opened and the sealant layer will be on the surface side. If the sealant layer is stretched and deformed before it is stretched and deformed before it is sandwiched between the respective base film layers on the back side and sheared, the sealant layer will be stretched and deformed. Since it becomes very difficult to tear the groove, the maximum width of the groove is set to 1000 μm here.

[0018]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is an exaggerated view of an embodiment of the present invention. FIG. 1 (a) is a plan view of a laminated film, and FIG. 1 (b) is taken along line bb of FIG. 1 (a). Enlarged sectional views are shown respectively.

This is because when the sealant layer 2 is laminated on the base film layer 1 made of a known stretched plastic film by extrusion laminating, dry laminating, etc., for example, at the time of winding operation after completion of the laminating operation. Or, in the slitter work of cutting a wide laminated film into one having a width of one bag, the base film layer 1 of the laminated film is irradiated with a laser beam and the laser beam is made to travel in the film width direction. The base film layer 1 is formed with the continuous groove 3 melted at a predetermined depth and width. This means that the melted base film causes raised ridges 4 on each side of the continuous groove 3 which function to increase the tear resistance of the bag. Therefore, it is possible to effectively prevent the tear of the bag from escaping from the groove 3.

Here, the depth of the continuous groove 3 is about 50% or more and 60% or less of the thickness of the base film layer 1 in relation to the bag tensile strength, in other words, bag breaking strength. Is preferable, and its width is preferably 100 to 1000 μm in relation to thermal strain of the laminated film, bag manufacturing error, and the like.

It should be noted that the continuous groove 3 can also be formed by forming a plurality of two or more pieces in the laminated film portion required to form one packaging bag. The position can be appropriately selected as required.

In the laminated film constituted as described above, when the base film layer 1 is a biaxially extended nylon film layer having a thickness of 15 μm and the sealant layer 2 is a polyethylene layer having a thickness of 60 μm, The tensile strength of the film based on JISZ1526 when the width of the groove 3 was 400 μm and the depth was changed variously was as shown in Table 1.

[0023]

[Table 1]

As shown in Table 1, the tensile strength of about 2.5 kgf / 15 mm width or more, which is generally required for laminated films for packaging bags used for packaging liquids and viscous materials. In order to bring about the above, it is understood that the groove depth needs to be about 60% or less of the thickness of the biaxially stretched nylon film layer.

Further, the force required for opening the bag when the above laminated film is formed into a 70 mm × 90 mm length packaging bag by a three-way seal is shown in FIG. 2 (a) and FIG. 2 (b), respectively. When measured in each of the tear directions shown, the results are as shown in Table 2.

[0026]

[Table 2]

According to the results shown in Table 2, in order to provide a required tear force of about 350 gf or less, which is an index for easy opening of the packaging bag, the groove depth is set to be the biaxially stretched nylon film. Obviously, it is suitable to have about 50% or more of the layer thickness.

Thus, here, the depth of the groove 3 is set to about 50% or more and 60% or less of the thickness of the base film layer 1 in relation to the type of the article to be packaged, the size of the packaging bag, etc. It is possible to open the packaging bag sufficiently easily while ensuring excellent bag breaking strength.

By the way, in the unsealing test of the above-mentioned packaging bag, when the direction of progress of the tear was observed, it was found that the continuous groove formed by the irradiation of the laser beam had a depth of the biaxially stretched nylon film layer. For 40% or more of the thickness, the crevice did not deviate from the groove 3. Therefore, according to this laminated film, it is possible to sufficiently secure the easy-opening property of the packaging bag, and at the same time, it is possible to accurately advance the tear of the seal along the continuous groove 3.

Although the laminated film shown in FIG. 1 has been described above, the continuous groove can be formed not only in a linear shape but also in a curved shape. For example, as shown in FIG. In each of the front surface side portion and the back surface side portion of the packaging bag manufactured by, it is possible to form only the corners of the bag so as to extend corresponding to each other.

FIG. 4 is a diagram showing another example of the laminated film, which is one in which the intermediate layer 5 is interposed between the base film layer 1 and the sealant layer 2, and The groove 6 having a depth equal to or less than the thickness is intermittently melted and formed in a perforated shape with a laser beam.

In this example, the base film layer 1 is a biaxially stretched nylon film layer having a thickness of 15 μm, and the intermediate layer 5 and the sealant layer 2 are each a polyethylene layer and an ethylene layer having a total thickness of 45 μm. When a vinyl acetate copolymer layer is used, the length a of each groove 6 that extends intermittently over the entire width of the laminated film is changed to three types of 0.5 mm, 1.0 mm and 1.5 mm, and the groove distance is changed. When b is changed to three types of 0.5 mm, 1.0 mm and 1.5 mm, and further changed to two types of groove depths of 7 μm and 20 μm, while the groove width is set to a constant width of 400 μm, The tensile strength of the laminated film and the required tearing force of the packaging bag, as described above, are as shown in Table 3, respectively.

[0033]

[Table 3]

According to Table 3, when the groove 6 is formed in a perforated shape, even if the depth exceeds the thickness (15 μm) of the base film layer (20 μm), the required tension is still maintained. It is clear that sufficient strength (about 2.5 kgf / 15 mm width) can be secured, but in this case, the coating layer that may be formed on the inner surface of the base film layer is damaged by the groove 6. Therefore, the packaging bag cannot exhibit an excellent barrier property against gas, water vapor and the like.

On the other hand, regarding the easy-opening property, the laminated films of No. 9, No. 13 to 15 and No. 17 to 19 were related to the combination of the length, the interval and the depth of the groove. It can be seen that the packaging bag used can give almost satisfactory results. Therefore, even in the case of a laminated film in which the groove 6 having a depth of 50% or less of the thickness of the base film layer is formed in a perforated shape, it is possible to select the combination of the groove length, spacing, etc. In addition, it is possible to effectively induce the progress of the tearing of the bag while sufficiently securing the necessary bag breaking strength and the easy opening property.

Incidentally, also in this example, it is a matter of course that the perforation groove can be formed in a curved shape or another required shape.

The present invention has been described above based on the illustrated examples, but the present invention is also applied to laminated films having various known laminated structures other than those shown in the drawings, for example, laminated films including paper, aluminum foil and the like. be able to.

[0038]

[Effect of device]

 Thus, according to this invention, it is possible to secure the excellent bag breaking strength of the packaging bag and to prevent the coating layer that may be formed on the inner surface of the base film layer from being damaged. The easy opening property is sufficiently secured, and the tearing direction of the bag can be accurately guided by the groove, which causes the package to be scattered, dropped, or spouted when opening the packaging bag. It is possible to almost completely eliminate such fears.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a tearing direction of a packaging bag.

FIG. 3 is a diagram showing an example of forming a curved groove.

FIG. 4 is a view showing another embodiment of the present invention.

[Explanation of symbols]

 1 base film layer 2 sealant layer 3 continuous groove 4 raised protrusion 5 intermediate layer 6 groove

Claims (5)

[Scope of utility model registration request] 1. A laminated film comprising a base film layer made of a stretched plastic film and a sealant layer, wherein the base film layer has a thickness of about 50% or more of 6 or more.
A laminated film for a packaging bag, which comprises at least one continuous groove having a depth of 0% or less, and ridges formed on both sides of the continuous groove. 2. The packaging bag according to claim 1, wherein the continuous groove is formed in line symmetry with respect to a center line in the width direction of a laminated film that is formed in a folded posture in the width direction. Laminated film for. 3. The laminated film for a packaging bag according to claim 2, wherein the continuous groove extends linearly. 4. The laminated film for a packaging bag according to claim 2, wherein the continuous groove extends in a curved shape. 5. A laminated film comprising a base film layer made of a stretched plastic film and a sealant layer, wherein the laminated film is provided with perforations having a depth smaller than the thickness of the base film layer. In addition, a laminated film for a packaging bag, in which raised portions are formed on both sides of each groove.