JP2013056709A - Paper bag with innermost layer formed of resin layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper bag with an innermost layer formed of a resin layer in which an opening has easy peeling performance and is easily opened after sealed and a packing part is firmly stuck and hindered as much as possible from an opening.SOLUTION: The paper bag 20 includes the innermost layer formed of the resin layer and formed with the packing part 21. The resin layer is formed of an extrusion-manufactured resin film with easy peeling performance. Out of the extrusion-manufactured resin film with easy peeling performance, portions in an extruding direction are positioned to the opening 23 and a bottom 22 of the paper bag, portions in a direction orthogonal to the extruding direction are positioned to the packing part 21, the mutual resin layers of the opening 23 and the bottom 22 are heat-sealed in the direction orthogonal to the extruding direction of the resin film, and the mutual resin layers of the packing part 21 are heat-sealed in a direction parallel to the extruding direction of the resin film.

Description

  The present invention relates to a paper bag having an innermost layer of a resin layer manufactured by specially processed paper obtained by sticking a film-like resin layer to paper, in particular, kraft paper, and in particular, an innermost layer resin constituting the mouth of such a paper bag. The present invention relates to an improvement in a paper bag in which layers are brought into close contact with each other by heat sealing to seal the mouth portion, and then the mouth portion is easily opened.

  Generally, in a paper bag made of kraft paper or the like, the mouth portion is sealed by a flap formed to protrude from the mouth portion, and a cut tape is provided on the flap to facilitate the opening of the sealed mouth portion. It is known that the cut tape is stretched to tear the flap, thereby facilitating the opening of the mouth.

  On the other hand, in order to give the paper bag a function such as moisture-proofing or improving the sealing performance, specially processed paper coated with a film-like resin layer such as polyethylene is used on the paper, thereby producing a paper bag with the innermost layer being a resin layer. To do.

And when this innermost layer seals the mouth part of the paper bag of a resin layer, the resin layers of a mouth part are heat-sealed and adhered, and thereby a mouth part is sealed.

  On the other hand, in such a paper bag having an innermost resin layer, when opening the heat-sealed mouth portion, the mouth portion has high adhesion strength, so it is easy to open the mouth portion manually by an operator. Instead, the mouth is normally opened using a jig such as scissors or a cutter.

JP2002-370751

  By the way, as described above, in a paper bag having a resin layer as the innermost layer, when opening the heat-sealed mouth portion, the mouth portion is opened using a jig such as scissors or a cutter. The unpacking operation is extremely complicated.

  In addition, in order to solve the above-mentioned problems, a resin layer is formed by coating a resin having an easy peel property that can easily peel off the heat-sealed portion as the innermost resin layer, thereby forming the mouth portion. It is also conceivable to use a paper bag having a resin layer as the innermost layer so as to facilitate the opening.

  On the other hand, in the case of a large-sized paper bag in which the weight of the contents to be stored exceeds 1 kg, the paper bag is formed with a body pasting part due to its structure.

In this case, when using a specially processed paper that is simply coated with a resin layer having an easy peel property on the innermost layer, and manufacturing a paper bag having a body pasting part, the sealing of the body pasting part is performed in the same manner as the sealing of the mouth part. The easy-peeling resin layers must be sealed by heat sealing.

However, because the easy-to-peel resin layer is sealed by sealing the heat-peelable resin layers with each other, it has an easy-peel property that easily peels off. When stacking paper bags containing paper, etc., a large force is applied to the cylinder pasting part, and the resin layers of the cylinder pasting part are easily peeled off and opened to maintain the strength as a large paper bag. There was a difficulty that could not be.

  In view of the circumstances described above, the present invention has an easy peel property at the mouth, and can be easily opened after sealing, and the body affixed portion is firmly fixed so that the opening is prevented as much as possible. It is an object to provide a paper bag having a resin layer as the innermost layer.

  In order to solve the above-described problem, in the first invention of this application, in the paper bag in which the innermost layer on which the body pasting portion is formed is a resin layer, the resin layer is an extruded manufactured resin film having an easy peel property. In the resin film having an easy peel property that is produced by extrusion, the portion in the extrusion direction is positioned at the mouth and bottom of the paper bag, and the portion in the direction perpendicular to the extrusion direction is in the body pasting portion. While being positioned, the resin layers at the mouth and bottom are heat sealed in a direction orthogonal to the extrusion direction of the resin film and sealed, and the resin layers at the body pasting portion are sealed with the resin. The film is heat sealed in a direction parallel to the extrusion direction of the film and sealed.

  Further, in the second invention of this application, in the paper bag in which the innermost layer on which the body pasting portion is formed is a resin layer, the resin layer is a resin film having an easy peel property produced by extrusion, and the extrusion production is performed. Of the resin film having an easy peel property, the portion in the extrusion direction is positioned at the mouth and bottom of the paper bag, and the portion in the direction orthogonal to the extrusion direction is positioned at the body pasting portion, and the mouth The bottom resin layers are heat-sealed in a direction orthogonal to the extrusion direction of the resin film and sealed, and the resin layers of the body pasting portion are bonded together via a hot-melt molten resin. It is characterized by being sealed.

  According to the paper bag of the present application in which the above-described barrel pasting portion is formed, the extruded film is positioned at the mouth and bottom of the paper bag, and the direction orthogonal to the extrusion direction, among the resin film having an easy peel property produced by extrusion. Is positioned on the barrel pasting portion, and the resin layers at the mouth and bottom are heat sealed in a direction orthogonal to the extrusion direction of the resin film and sealed, and the resin at the barrel pasting portion is sealed. The layers are sealed by heat sealing in a direction parallel to the extrusion direction of the resin film.

The inventor of the present application, after earnest research, in the paper bag in which the innermost layer of the above-described structure is a resin layer, the sealing strength (peeling strength) of the mouth is small and has an easy peel property, and the sealing strength ( It has been found that the peel strength is large and has no easy peel property.

And in the paper bag in which the innermost layer of the above-mentioned structure is a resin layer, the mouth and bottom have easy peel properties and can be easily opened after sealing, and the cylinder pasting portion is firmly fixed and Since the unsealing is prevented as much as possible, it was possible to provide a paper bag having a resin layer as the innermost layer, which is easy to open and has a strong strength as a paper bag.

  In addition, the resin layers of the cylinder pasting part were bonded to each other via a hot-melt molten resin and sealed, thereby maintaining the strength of the cylinder pasting part and improving the manufacturing efficiency of the paper bag.

FIG. 1 is a conceptual perspective view of specially processed paper constituting the paper bag of the present invention. FIG. 2 is a conceptual diagram showing a process of manufacturing a resin layer of a paper bag according to the present invention by an inflation method. FIG. 3 is a conceptual perspective view showing a state in which a part of a film tube manufactured by the inflation method of FIG. 2 is cut. FIG. 4 is a conceptual perspective view showing a state in which the film tube shown in FIG. FIG. 5 is a plan view showing a resin layer of a paper bag made of a film according to the present invention. FIG. 6 is a perspective view showing a heat sealing process of a body pasting portion of a paper bag according to the present invention. FIG. 7 is a plan view showing a state in which the body pasting portion of the paper bag according to the present invention is heat-sealed. 8 is a conceptual sectional view of the FF of FIG. FIG. 9 is a plan view showing a state where the bottom of the paper bag according to the present invention is heat-sealed. FIG. 10 is a conceptual cross-sectional view showing a state in which contents are put into the paper bag of the present application. FIG. 11 is a conceptual cross-sectional view showing a state in which a mouth portion of a paper bag containing contents is sealed. FIG. 12 is a plan view showing a state in which the mouth portion of the paper bag according to the present invention is sealed by heat sealing. FIG. 13 is a table showing experimental results for confirming easy peelability (openability) of the mouth portion of the paper bag according to the present invention. FIG. 14 is a table showing the experimental results for confirming the adhesive strength of the body pasting portion of the paper bag according to the present invention. FIG. 13 is a top view of the paper bag showing a direction in which a force for expanding the mouth of the paper bag according to the present invention is applied. FIG. 14 is a plan view of the paper bag showing the direction of expanding the body pasting portion of the paper bag according to the present invention.

  Hereinafter, an embodiment of a paper bag in which the innermost layer according to the present invention is a resin layer will be described in detail.

  FIG. 1 is a conceptual perspective view showing a specially processed paper 1 which is a basic structure of a paper bag in which the innermost layer according to the present invention is a resin layer.

  The specially processed paper 1 includes a rectangular kraft paper 2, a rectangular resin film 3 having easy peel properties, and a rectangular adhesive layer resin 4 which is an adhesive layer for adhering the film 3 to the kraft paper 2. It consists of and.

  Among these, the adhesive layer resin 4 is constituted by extrusion lamination, and the film 3 is subjected to corona treatment on one side located on the adhesive layer resin 4 side in order to secure an adhesive force with the adhesive layer resin 4. ing.

  On the other hand, the film 3 having the above-described easy peel property is manufactured by a known inflation method shown in FIG.

Briefly explaining this inflation method, the thermoplastic resin 12 is continuously extruded from the extruder 11 through the ring-shaped mold 10 in the direction of arrow A (extrusion direction) in the form of a tube. The air is blown and expanded to cool, and is folded on a roller 14 and wound up as a two-layer film.

Then, the tube wound up is cut into a cylindrical tube 13 having a length corresponding to the length of the paper bag, as shown in FIG. 3, and then, as shown in FIG. The tube 13 is cut by making a cut 14 along the pushing direction (arrow A) so as to correspond to the portion.

  Of the edge portions of the rectangular film 3 shown in FIG. 5, the edge portions 3a and 3b of the film 3 corresponding to the extrusion direction (arrow A) are portions corresponding to the mouth portion or the bottom portion of the paper bag later. Yes, the edge portions 3c and 3d corresponding to the direction (arrows B and C) orthogonal to the extrusion direction (arrow A) become the portions corresponding to the body pasting portion of the paper bag later.

In addition, in order to ensure the easy peel property, the rectangular film 3 described above is a heat produced by mixing polypropylene random copolymer (PP) and low density polyethylene (LDPE) at a blending ratio of 50:50 in the production by the inflation method. Manufactured from a plastic resin.

  In producing the film 3 having the above-described easy peel property, the blending ratio of the polypropylene random copolymer (PP) and the low density polyethylene (LDPE) is not only the blending ratio of 50:50 described above, but also 30:70. Or the compounding ratio of 70:30 may be sufficient. Further, in order to secure a better opening property (easy peel property), an anti-blocking agent such as talc or silica or a lubricant such as oleic amide may be added. (In addition, it goes without saying that easy peel properties (EP function) can be ensured without adding these lubricants.)

  As shown in FIG. 1, the above-mentioned film 3 having an easy peel property is attached to a rectangular kraft paper 2 through an adhesive layer 4 to produce a specially processed paper 1, which is a perspective view of FIG. The film 3 is folded as shown in FIG. 5A, and the edges 3c and 3d of the film 3 positioned in the innermost layer of the body pasting part are overlapped, and as shown by an arrow D, the film 3 is pushed out by using a jig such as a hot plate ( When heat sealing is performed in a direction parallel to the arrow A) in FIG. 5, the body pasting portion 21 of the paper bag 20 is sealed as shown in FIG.

In the above description, the structure of the specially processed paper 1 has been explained in an easy-to-understand manner. However, in the actual production of the specially processed paper 1, the winding of the film 3 and the winding of the kraft paper 2 are performed using a molten resin (or adhesive). Thus, winding of the specially processed paper 1 is manufactured. Then, the take-up is made into a cylinder, and the specially processed paper 1 in the shape of a cylinder is cut into a predetermined length so that the bottom is sealed.

Next, as shown in FIG. 8 shown in the FF cross section of FIG. 7, the edges 3 b of the innermost layer film 3 positioned at the bottom 22 of the paper bag 20 are aligned in the direction indicated by the arrow F in FIG. When heat sealing is performed in a direction orthogonal to the extrusion direction (arrow A in FIG. 5) using a jig such as a hot plate, the bottom 22 is sealed, and the innermost layer with the opening 23 opened is a resin bag 20 having a resin layer. Complete. As shown in FIG. 9, the heat-sealed bottom portion 22 is located slightly above the lower end of the paper bag 20, thereby securing a grip margin necessary for opening the bottom portion 22.

  Next, the operation of the paper bag 20 in which the innermost layer according to the present invention is a resin layer will be described.

Using the paper bag 20 completed according to FIG. 9, as shown in the sectional view of FIG. 10, the contents K are inserted from the mouth 23 as shown by the arrow H, and thereafter, as shown in FIG. The edge 3a of the film 3 located in the innermost layer of the film is orthogonal to the direction indicated by the arrow J in FIG. 12, that is, the direction of extrusion of the resin film 3 (arrow A in FIG. 5) using a jig such as a hot plate. When heat-sealing, the mouth 23 is sealed.

  In the case of FIG. 12 as well, the heat-sealed mouth portion 23 is located slightly below the upper end of the paper bag 20, thereby securing a grip margin necessary for opening the mouth portion 23.

Next, experimental comparison results will be described in detail with respect to the easy peel property between the specific example of the paper bag 20 having the above-described structure and the specific example of the paper bag having other specifications.
[Experiment 1]

Specific example of a paper bag 20 according to the present invention: in FIG. 1, 78 g / m 2 of kraft paper: 2 PE layer (adhesive layer) of 15: 15 μm: Specially processed paper 1 of 40 μm of film 3 This application Paper bag 20 (FIG. 12).

  On the other hand, there are the following two types of paper bags compared.

(A) The paper bag which changed only the film of the code | symbol 3 of FIG. 1 into the commercially available easy peel CPP film.

(B) A paper bag in which only the film denoted by reference numeral 3 in FIG. 1 is changed to a polypropylene random copolymer (PP) single-piece extruded laminate.

In addition, each heat sealing condition of each paper bag mentioned above was 180 degreeC and 10 second, and confirmation of easy peel property confirmed the peeling state of the opening | mouth part by hand peeling.
The results were as follows.

Paper bag of the present application: The mouth was easily peelable.

Paper bag of (A): Delamination (peeling) occurred in the PE layer without peeling at the PP layer (resin layer).

(B) Paper bag: PP layer (resin layer) was firmly bonded to each other, and the mouth part was not peeled off, and the paper layer was broken.

Result: In Experiment 1, the paper bag 20 according to the present application obtained good peeling performance of the mouth 23.
[Experiment 2]

Next, for a specific example of a multi-layer paper bag of 78 g / square meter × 2 layers of kraft paper and an inner bag of paper bag 20 of the present application, a comparison of the peel strength between the mouth and the trunk was confirmed by experiments. .

(A) About the experiment which compared the peeling strength of a mouth part and a body sticking part.
The experimental results will be described in detail below.

In this experiment, the sealing conditions of the paper bag 20 of the present application are as follows. Each part of the mouth portion 23, the body pasting portion 21, and the bottom portion 22 (room temperature at the time of sealing: 28 ° C.) shown in FIG. Sealing was carried out at a pressure of 0.4 MPa at a sealing temperature of 10 to 240 ° C.

The mouth 23 and the bottom 22 are sealed by moving the hot plate in a direction perpendicular to the longitudinal direction of the paper bag, as described above, and the case where the body is attached is parallel to the longitudinal direction of the paper bag. Moved and sealed.
Number of test points: 7 points.
The results are as shown in the table of FIG.

In the table of FIG. 13, the symbol * indicates that the paper layer was torn when the cylinder pasting part was peeled off, that is, the part marked with * indicates the seal layer (resin layer) of the cylinder pasting part. This means that the paper layer was torn without being peeled, and this indicates that the sealing layer of the cylinder pasting portion was strongly maintained in an adhesive state.

The peeling direction of the mouth portion 23 is a direction of pulling in a direction perpendicular to the width direction of the paper bag 20 as shown in FIG. The peeling direction is a direction of pulling in a direction perpendicular to the longitudinal direction of the paper bag 20, as shown in FIG.

The following facts were found from the results of the experiment shown in the table of FIG.

When the paper bag 20 according to the present invention was sealed at 180 ° C. to 240 ° C., the mouth part was peeled off at about 2.9 to 5.0 N / 15 mm, and the peel strength was substantially constant. This indicates that it can be easily peeled off manually by an operator (peeling strength: 5 N / 15 m or less), and because it is less dependent on temperature, adjustment at the time of manufacture can be reduced.

Also, specimens were collected from 7 locations in the bag width direction and the peel strength was confirmed, but the peel strength was low, and the peel strength was 5 N / 15 mm or less regardless of the shape of the bag, that is, the shape of the paper bag with or without crease. The condition was also good.

In addition, when the sealing is performed under the same conditions from the above-described experimental results, the peel strength is greatly different between the mouth portion 23 and the body pasting portion 21. From this result, in the paper bag 20 of the present application, the mouth portion 23 has an easy peel property. Then, after sealing, it was easily opened, and it was found that the body pasting portion 21 was firmly fixed and the opening was prevented as much as possible.

In the above embodiment, as shown in FIG. 6, the body pasting part 21 is sealed by heat sealing. However, in the manufacture of a paper bag, this part of the heat sealing process takes time and leads to a decrease in manufacturing efficiency. Since there is a fear, a known hot melt melt resin (not shown) is applied at a high temperature between the edges 3c and 3d of the film 3 located in the innermost layer of the cylinder pasting portion 21 shown in FIG. The edge portions 3c and 3d of the film 3 were instantly bonded and sealed through the hot melt type molten resin.

(B) About the experiment of the peeling strength of the said sticking part by the drop experiment of the paper bag 20 which sealed between the edge parts 3c and 3d of the film 3 located in the innermost layer of the trunk | drum sticking part 21 mentioned above with hot-melt-type molten resin.

Kraft paper 78g / square meter x 2 layers + 1 layer with the above-mentioned paper bag 20 of the present application as inner bag A total of 3 layers of multi-layer paper bags, with the mouth and bottom sealed at 180 ° C to 240 ° C, and the body affixed part hot melted This product (sample A) sealed with a molten resin and a multilayer paper bag with a total of three layers (the sample 21 has a peel strength (5 N / 15 mm) equivalent to the mouth 23 and the bottom 21) (sample) For the bags using B), the number of drops until the bags were broken in the drop test was compared by experiment.

Drop condition: height 1.2 m, contents: resin pellet, test environment: 24 ° C., 60% RH.
The results are as shown in the table of FIG.

  In the table of FIG. 14, the symbol * indicates the number of drops required to break the bag at the body pasting portion.

Even in this case, it was found that the peel strength of the cylinder pasting part 21 is maintained high, the cylinder pasting part 21 is firmly fixed, and its opening is prevented as much as possible. From the above experimental results, It was confirmed that this product has sufficient strength as a paper bag for storing contents of 1 kg or more.

In the above embodiment, the bottom portion 22 and the mouth portion 23 of the paper bag 20 are used while being heat-sealed. However, the present invention is not limited to the above embodiment, and the bottom portion 22 and the mouth portion 23 are used. In order to prevent the load from the contained contents from being directly applied to the heat seal portion of the paper bag 20, the paper bag 20 immediately before reaching the heat seal portion of the bottom portion 22 and the mouth portion 23 from the center portion of the paper bag 20 is You may make it use it by bending in the direction orthogonal to a direction, respectively. When the bottom portion 22 and the mouth portion 23 are bent as described above, the load from the stored contents is not directly applied to the bottom portion 22 and the mouth portion 23, and even when the paper bag 20 is dropped, the bottom portion 22 and the mouth portion 23 are opened. Was able to be prevented.

  As described above in detail, the innermost layer of the paper bag according to the present invention has an easy peel property at the mouth, and is easily opened after sealing, and the trunk pasting portion is firmly fixed and opened. Suitable for paper bags that are blocked as much as possible.

3 ... Resin film (resin layer),
20 ... Paper bag 21 with innermost layer being resin layer ... Body trunk 22 ... Bottom 23 ... Mouth A ... Extrusion direction B, C ... Direction orthogonal to extrusion direction

Claims (5)

In the paper bag of the resin layer is the innermost layer where the trunk pasting part is formed,
The resin layer is a resin film made of polypropylene random copolymer (PP) and low density polyethylene (LDPE) having an easy peel property produced by extrusion by an inflation method, and the resin having an easy peel property produced by extrusion. Of the film, the portion in the extrusion direction is positioned at the mouth and bottom of the paper bag, and the portion in the direction perpendicular to the extrusion direction is positioned at the body pasting portion,
The resin layers at the mouth and bottom are heat sealed in a direction orthogonal to the extrusion direction of the resin film and sealed, and the resin layers at the body pasting portion are sandwiched with a hot-melt molten resin. The resin film is a resin film in which polypropylene random copolymer (PP) and low density polyethylene (LDPE) are mixed, and the mixing ratio is 30:70 to 70:30. A paper bag whose innermost layer is a resin layer.
The paper bag according to claim 1, wherein the paper bag is a pleated paper bag.
The paper bag according to claim 1, wherein the paper bag is a paper bag with a crease.
The paper bag according to claim 1, wherein the paper bag is used as an inner bag of a multilayer paper bag.
2. The paper bag according to claim 1, wherein the paper bag immediately before reaching the heat seal portion of the bottom part and the mouth part from the center part of the paper bag is bent in a direction perpendicular to the longitudinal direction thereof.

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