JP2000025835A - Packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging bag which can be unsealed by hands, suppresses generation of wrinkles or blocking on a heat seal surface, and is excellent in appearance. SOLUTION: In a packaging bag, a lamination film containing a biaxially oriented syndiotactic polystyrene film of 10-60 μ in thickness and an unoriented polyolefin resin film of 10-80 μ in thickness is heat-sealed on an edge part of an outer periphery of the bag with 3-10 mm in width so that the biaxially oriented polystyrene resin film located outside the bag, and the unoriented polyolefin resin film inside the bag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag for packaging small quantities of articles such as medicines and foods, and more particularly to a packaging bag which can be easily opened.

[0002]

2. Description of the Related Art In packaging bags for packaging small quantities of articles such as pharmaceuticals and foods, the effect of being easily opened by hand without making a cut at the tearing point or applying special processing to the outer edge. As a packaging bag with
No. 71783 discloses a laminated film of a biaxially oriented polystyrene film having a thickness of 10 to 60 μm and a heat-sealable unstretched polyolefin film having a thickness of 10 to 80 μm. The heat-sealing unstretched polyolefin film is positioned so as to be inside the bag, and heat-sealed so that a heat-sealing line having a width of 3 to 10 mm is positioned at the outer peripheral edge of the bag. A technique relating to a packaging bag is disclosed in Packaging Bags.

[0003] However, the aforementioned Japanese Patent Publication No. 4-71783.
The packaging bag described in Japanese Patent Application Publication No. H07-27138, is a biaxially oriented polystyrene film made of general-purpose polystyrene, and is made of a heat-sealing unstretched polyolefin film, and has a problem that wrinkles occur on the heat-sealing surface during heat sealing.
Such wrinkles on the heat sealing surface have the disadvantage that the appearance as a packaging bag is significantly reduced and the commercial value is greatly reduced.
On the other hand, in order to prevent wrinkles on the heat sealing surface during heat sealing, a biaxially oriented polystyrene-based resin film is biaxially oriented polyethylene terephthalate film (PET),
There are methods to make biaxially oriented polypropylene-based film (OPP) and biaxially oriented nylon-based film (ONy),
These films are difficult to open by hand.

[0004]

DISCLOSURE OF THE INVENTION The present invention has an effect that it can be easily opened by hand without making a cut at a tearing place in advance or applying special processing to an outer edge portion, and has a heat seal. It is an object of the present invention to provide a packaging bag which has a beautiful appearance by suppressing wrinkles and blocking of the surface.

[0005]

Means for Solving the Problems The present inventor has made intensive studies to achieve the above object, and as a result, has accomplished the present invention. That is, the present invention provides a biaxially oriented polystyrene resin film having a thickness of 10 to 60 microns and a thickness of 10 to 8
A laminated film containing a 0-micron unstretched polyolefin-based resin film and a biaxially stretched polystyrene-based resin film positioned outside the bag and the unstretched polyolefin-based resin film positioned inside the bag and heat-sealed. In the packaging bag, the biaxially stretched polystyrene-based resin film is a biaxially stretched syndiotactic polystyrene film.

An aluminum foil having a thickness of 3 to 70 μm is interposed between a biaxially oriented polystyrene resin film having a thickness of 10 to 60 μm and an unstretched polyolefin resin film having a thickness of 10 to 80 μm. The laminated film is positioned so that the biaxially oriented polystyrene resin film is on the outside of the bag and the unstretched polyolefin resin film is on the inside of the bag.
A packaging bag formed by heat-sealing such that a 10-mm heat-sealing line is located, wherein the biaxially stretched polystyrene-based resin film is a biaxially stretched syndiotactic polystyrene film. .

Hereinafter, the present invention will be described. The most different point of the present invention from the prior art is that the polystyrene film has a syndiotactic structure. The role of the constituent element of the present invention, which is different from the above-mentioned conventional technology, has an effect that it can be easily opened by hand, and suppresses the occurrence of wrinkles on the heat-sealing surface during heat-sealing. Is to be obtained.

The syndiotactic polystyrene film according to the present invention is, as described in JP-A-62-104818, a metallocene comprising a combination of a titanium compound such as titanium halide or alkoxytitanium with an alkylaluminoxane. It can be obtained by polymerizing a styrene monomer with a single-site catalyst, copolymerizing a styrene monomer with a nucleus-substituted styrene monomer such as alkyl styrene or halogenated styrene, or a mixture thereof by extrusion film formation.

The syndiotactic polystyrene used in the present invention is a syndiotactic structure having a stereoregularity, that is, a phenyl group or a phenyl group which is a side chain with respect to a main chain formed from carbon-carbon bonds. It mainly has a three-dimensional structure alternately located in the opposite direction, and its stereoregularity is quantified by a nuclear magnetic resonance method (NMR method). The three-dimensional structure measured by the NMR method can be represented by the abundance ratio of a plurality of continuous structural units, for example, a dyad in the case of two, a triad in the case of three, and a pentad in the case of five, The syndiotactic polystyrene referred to in the present invention is 85 in dyad.
% Or a pentad having a syndiotactic structure of 50% or more.

The syndiotactic polystyrene film can be used alone, but in order to improve the workability during film formation and the impact resistance of the obtained film, general-purpose polystyrene (GPPS), styrene butadiene At least one polymer selected from the group consisting of copolymers and the like can be added at a ratio of 1 to 90% by weight, preferably 2 to 80% by weight. If the addition amount is less than 1% by weight, the effect of improving workability and impact resistance may be small, and if it is 90% by weight, the effect of suppressing the generation of wrinkles on the heat sealing surface may decrease.

Further, from the viewpoint of enhancing the slipperiness of the film,
High impact polystyrene (HIPS) can be added. In this case, the addition of HIPS tends to reduce the transparency of the film, so that 5% by weight, preferably 3% by weight, is preferred.
It is preferable that the content be not more than% by weight. In addition to the above, release agents,
A mixture of a heat stabilizer, an ultraviolet absorber, an antioxidant, a colorant, a plasticizer, an oligomer, and other conventional additives may be used as long as the characteristics of the present invention are not impaired.

The biaxially stretched syndiotactic polystyrene film used in the present invention is obtained by forming the above resin into a film by an inflation method or a tenter method. The syndiotactic polystyrene-based film used in the present invention is required to be a biaxially stretched film from the viewpoint that the bag can be easily torn open in any direction both in the longitudinal direction and the transverse direction, and it is necessary that the film be sufficiently oriented. Is a film having
As a stretching method, there is a method in which a raw sheet is once formed by extrusion molding from the above-described resin and the raw sheet is biaxially stretched, or a method in which an inflation film is directly formed and biaxially stretched.

[0013] In packaging bags where transparency is important,
It is necessary to use a highly transparent biaxially stretched syndiotactic polystyrene film. In the method of once forming and stretching a raw sheet, in order to obtain a highly transparent film, it is preferable to rapidly cool the resin melted by heating when forming the raw sheet. In quenching, it is preferable to set the refrigerant temperature to 80 ° C. or lower, preferably 50 ° C. or lower. If the refrigerant temperature is higher than 80 ° C., crystallization occurs partially and the transparency is lowered. In the stretching treatment of the raw sheet, the stretching temperature is preferably lower than the low-temperature crystallization temperature, and if the temperature is higher than that, the transparency is reduced. The stretching ratio is not particularly limited, but may be, for example, 2 to 10 times. The stretching may be performed in the longitudinal direction and the transverse direction at the same time, but may be sequentially performed in any order.

The thickness of the biaxially stretched syndiotactic polystyrene resin film is 10 to 60 microns, preferably 15 to 50 microns. If it is less than 10 microns, the film strength is not sufficient, and if it is more than 60 microns, the tearing property is reduced. The orientation of the film is represented by the heat shrinkage stress, and the heat shrinkage stress in the biaxial direction is 1 kg / cm ^{2 to} 60 kg / c from the viewpoint of tearability.
m ² , more preferably ² kg / cm ^{2 to} 50 kg / cm ² . If it is less than 1 kg / cm ² , the film is not sufficiently oriented and the tearing property is poor, and it is difficult to tear by hand and open. If it is larger than 60 kg / cm ² , a complicated process is required for the production of the biaxially stretched syndiotactic polystyrene resin film.

The unstretched polyolefin resin film used as the heat seal layer in the present invention includes copolymers such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer and ethylene-acryl ester copolymer. A film made of an ion-crosslinked product of an acid copolymer (ionomer) and a copolymer of ethylene and an α-olefin polymerized using a metallocene catalyst is used. A releasing agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, a coloring agent, a plasticizer, an oligomer, other conventional additives, and the like may be added to these as long as the characteristics of the present invention are not impaired.

The thickness of the unstretched polyolefin film is
It is 10 to 80 microns, and preferably 10 to 60 microns, from the viewpoint of tearability and heat seal strength. If less than 10 microns, the heat seal strength is not enough,
Thicknesses greater than 80 microns result in greatly reduced tearability. The polyolefin film used in the present invention must be unstretched in order to make the most of the tear property of the biaxially stretched syndiotactic polystyrene resin film.

As a method of laminating an unstretched polyolefin film on a biaxially stretched syndiotactic polystyrene film, there are a wet lamination method, a dry lamination method, a hot melt lamination method, a solventless lamination method, an extrusion lamination method and the like. In the packaging bag of the present invention, the surface of the biaxially stretched syndiotactic polystyrene-based film can be subjected to a hydrophilizing treatment by electric discharge machining or the like, and an anchor coating agent can be applied in order to increase the adhesion during lamination. Also, when laminating a film-shaped unstretched polyolefin film, the film surface can be subjected to a hydrophilization treatment by electric discharge machining or the like, and an anchor coat agent can be applied.

When a film-shaped unstretched polyolefin film is laminated on a biaxially stretched syndiotactic polystyrene-based film by extrusion lamination, the temperature immediately below the die is raised as much as possible during extrusion in order to increase the adhesiveness. After the resin surface is oxidized or extruded into a film, the film surface can be subjected to an ozone treatment and a hydrophilic treatment. For polyolefin resins that cannot be extruded at a high temperature due to neck-in or thermal decomposition, etc., double lamination or tandem lamination in which high-pressure low-density polyethylene or the like is extruded at a high temperature in advance and then laminated is performed.

The packaging bag of the present invention comprises the above-mentioned biaxially stretched polystyrene resin film and the above-mentioned unstretched polyolefin resin film from the viewpoint of improving light-shielding properties and gas barrier properties and enhancing the storage stability of the contents. Between 3 and thick
70 micron aluminum foil can be provided. Conventionally,
In order to improve gas barrier properties and light blocking properties, there is a method of laminating biaxially stretched polyethylene terephthalate (PET) or biaxially stretched nylon film (ONy) on which aluminum is deposited, but these films are opened by hand. It can be difficult to do. On the other hand, when an aluminum foil having a thickness of 3 to 70 microns is arranged between the biaxially oriented polystyrene resin film and the unstretched polyolefin resin film, special processing is performed on the outer edge. It is possible to provide a packaging bag which has an effect that it can be easily opened by hand, has high gas barrier properties and light blocking properties, and has excellent preservability of contents.

Here, the aluminum foil is preferably 1N30 in the class of aluminum and aluminum alloy foil according to JIS 4160. Aluminum foil is roughly classified into hard foil and soft foil. When using soft foil, it is necessary to consider the rolling oil remaining on the surface. The thickness of the aluminum foil is 3 to 70 microns in consideration of gas barrier properties and tearability, but is preferably 5 to 50 microns. Thickness 3
Those having a diameter of less than micron have insufficient gas barrier properties, and those having a thickness of more than 70 μm have significantly reduced tearability and cannot be easily opened by hand.

The lamination of the biaxially stretched syndiotactic polystyrene resin film and the aluminum foil and the unstretched polyolefin resin film includes wet lamination, dry lamination, hot melt lamination, solventless lamination, and extrusion. There is a laminating method and the like. In order to increase the adhesion at the time of lamination, an anchor coating agent can be applied to the aluminum foil in the same manner as described above.

When an unstretched polyolefin film is laminated on an aluminum foil by extrusion lamination, the temperature immediately below the die is increased as much as possible during extrusion in order to increase the adhesiveness.
Oxidize the surface of the molten resin extruded into a film,
After being extruded into a film, the surface of the film may be subjected to an ozone treatment and a hydrophilic treatment. For polyolefin resins that cannot be extruded at a high temperature due to neck-in or thermal decomposition, etc., double lamination or tandem lamination in which high-pressure low-density polyethylene or the like is extruded at a high temperature in advance and then laminated is performed.

[0023] The packaging bag of the present invention can be used for packaging biaxially stretched syndiotactic polystyrene resin film or unstretched polyolefin when there is an obstacle due to static electricity when filling and packaging powdered pharmaceuticals, food powder soups and the like. An antistatic treatment such as kneading an antistatic agent into the base resin film or applying an antistatic agent to the film surface may be performed.
Further, the biaxially stretched polystyrene resin film or the unstretched polyolefin resin film to be used can be subjected to various printings.

In the bag of the present invention, the biaxially stretched syndiotactic polystyrene resin film is positioned outside the bag and the unstretched polyolefin film is positioned inside the bag. For this reason, when tearing by hand, it is considered that a fine crack is first generated in the biaxially stretched syndiotactic polystyrene-based resin film, and stress is concentrated at that point, and thereafter, it can be easily torn by hand.

It is essential that the bag of the present invention be heat-sealed so that a heat-sealing line having a width of 3 to 10 mm is located at the outer peripheral edge of the bag. If the width is less than 3 mm,
The strength of the seal is weak, and the bag is easily broken. On the other hand, when it exceeds 10 mm, the tearing property is reduced. As a method of heat sealing, for example, a so-called three-way seal, a four-way seal, or the like can be given. Examples of the form of the bag of the present invention include a bag as shown in FIG. The bag of the present invention having the above configuration,
It can be easily opened by tearing by hand in a direction substantially perpendicular to the heat seal line.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples. In addition, the evaluation method in this invention and the preparation method of the bag for packaging are as follows. (1) Heat Shrinkage Stress (ORS) According to ASTM-D1504, the vertical and horizontal values of the peak stress value in silicon hot water at the temperature of the Vicat softening point of the film + 30 ° C were determined. (2) Preparation of packaging bag Under the following conditions, the unstretched polyolefin-based resin film layers of the trial-produced laminated film were combined and heat-sealed on four sides to prepare a packaging bag having a length of 10 cm and a width of 10 cm. -Equipment used: TP-701 manufactured by Tester Sangyo Co., Ltd.-Seal width: 7 mm-Seal temperature: 160 ° C-Seal time: 0.3 seconds-Seal pressure: 2 kg / cm ²

[0027]

[Reference example] (Method for producing syndiotactic polystyrene)
600 ml of toluene, 120 mmol of methylaluminoxane, and 0.1% of tetraethoxytitanium were placed in a 1500 ml stainless steel autoflave purged with an inert gas.
6 mmol was added, followed by 600 ml of styrene, and a polymerization reaction was performed at 50 ° C. for 2 hours. After completion of the reaction, the reaction was stopped with hydrochloric acid-methanol, and the produced polymer was filtered and dried to obtain a polymer. As a result of determining the stereoregularity of the obtained polymer by NMR measurement, 99% had a syndiotactic structure.

[0028]

Example 1 The syndiotactic polystyrene obtained by the above method was extruded with a uniaxial extruder having a diameter of 30 mm to which a T-die was attached to prepare a 0.3 mm raw sheet. Cylinder temperature is 300 ° C, T-die temperature is 31
The temperature was 0 ° C., and the surface temperature of the sheet cooling roll was 40 ° C. This sheet was simultaneously biaxially stretched at a stretching temperature of 120 ° C. and 4 times in both the longitudinal and transverse directions to obtain a biaxially stretched syndiotactic polystyrene film having a thickness of 19 μm. The ORS of the obtained film was 8 in both the vertical and horizontal directions.
kg / cm ² .

The laminated side of the obtained biaxially stretched syndiotactic polystyrene film was subjected to a discharge treatment, and an imine-based anchor coat agent ("EL-" manufactured by Toyo Morton Co., Ltd.) was used.
420 ") was applied at a dry application amount of 4 mg / m ² and dried. As an unstretched polyolefin resin film, high-pressure low-density polyethylene (“L2340” manufactured by Asahi Kasei Corporation, melting point: 112 ° C.) is used.
It was extruded and laminated on a biaxially stretched syndiotactic polystyrene-based resin film so as to have a thickness of 30 microns at a temperature of ° C. The heat-sealing layers of the obtained laminated film were combined to form a four-sided sealed bag. This bag has sufficient heat seal strength, has good appearance without wrinkles on the heat seal surface, and from any position of the heat seal line,
It was easily opened by tearing by hand in a direction substantially perpendicular to the heat seal line.

[0030]

Example 2 A general purpose polystyrene (“Stylon 685” manufactured by Asahi Kasei Kogyo Co., Ltd.) was added to the syndiotactic polystyrene obtained by the above method so as to be 30% by weight. Extrude with 0.
A 3 mm raw sheet was prepared. Using a biaxial stretching machine, the sheet was simultaneously biaxially stretched at a stretching temperature of 115 ° C. and three times in the machine and transverse directions to obtain a 33 micron thick biaxially stretched syndiotactic polystyrene film. The ORS of the obtained film was 22 kg / in both the vertical and horizontal directions.
cm ² .

In the same manner as in Example 1, a discharge treatment was performed, an imine anchor coating agent was applied, and a high-pressure low-density polyethylene was extruded to form a heat seal layer. The heat-sealing layers of the obtained laminated film were combined to form a four-sided sealed bag. This bag has sufficient heat seal strength,
The heat-sealed surface had no wrinkles and good appearance, and could be easily opened from any position on the heat-sealed line by hand tearing in a direction substantially perpendicular to the heat-sealed line.

[0032]

Example 3 The laminate side of the biaxially stretched syndiotactic polystyrene film obtained in Example 1 was subjected to discharge treatment,
An unstretched polypropylene film ("Pyren Film-CT" manufactured by Toyobo Co., Ltd., thickness 25 microns, melting point 138 ° C) as an unstretched polyolefin resin film is used as an adhesive ("Seika Bond E-287" manufactured by Dainichi Seika Co., Ltd.).
It was dry-laminated using “Seika Bond C-28”). The heat-sealing layers of the obtained laminated film were combined to form a four-sided sealed bag. This bag has sufficient heat-sealing strength, has good appearance without wrinkles on the heat-sealing surface, and is easily torn by hand from any position of the heat-sealing line in a direction almost perpendicular to the heat-sealing line. I was able to open it.

[0033]

[Comparative Example 1] Instead of a biaxially stretched syndiotactic polystyrene-based film, a biaxially stretched general-purpose polystyrene-based film (“OPS film GM” manufactured by Asahi Kasei Corporation)
A laminated film was obtained in the same manner as in Example 1 except that a thickness of 20 μm, a vertical direction ORS of 15 kg / cm, and a horizontal direction ORS of 7 kg / cm) were used. The heat seal layers of the obtained laminated film were combined and heat-sealed, but wrinkles were observed on the seal surface.

[0034]

Comparative Example 2 Instead of a biaxially stretched syndiotactic polystyrene film, a biaxially stretched polyethylene terephthalate film ("S-25N" manufactured by Unitika Ltd.) was used.
C ", a thickness of 25 microns), and a laminated film was obtained in the same manner as in Example 1. The heat-sealing layers of the obtained laminated film were combined and heat-sealed, but it was difficult to open by hand.

[0035]

Comparative Example 3 Same as Example 1 except that a biaxially oriented polypropylene-based film (“OPU-1” manufactured by Tosello Co., Ltd., 25 μm in thickness) was used instead of the biaxially oriented syndiotactic polystyrene-based film. To obtain a laminated film. The heat-sealing layers of the obtained laminated film were combined and heat-sealed, but it was difficult to open by hand.

[0036]

Example 4 The syndiotactic polystyrene obtained by the above method was extruded with a uniaxial extruder having a diameter of 30 mm and a T-die, to prepare a 0.3 mm raw sheet. Cylinder temperature is 300 ° C, T-die temperature is 31
The temperature was 0 ° C., and the surface temperature of the sheet cooling roll was 40 ° C. This sheet was simultaneously biaxially stretched at a stretching temperature of 120 ° C. and four times in both the longitudinal and transverse directions to obtain a biaxially stretched syndiotactic polystyrene film having a thickness of 19 μm. The ORS of the obtained film was 8 in both the vertical and horizontal directions.
kg / cm ² .

The biaxially stretched syndiotactic polystyrene-based film was subjected to a discharge treatment on the side to be laminated, and then imine-based anchor coating agent (“E” manufactured by Toyo Morton Co., Ltd.)
L-420 ") was applied to a dry coating amount of 40 mg / m ² and dried. An imine-based anchor coating agent (“E30” manufactured by Toyo Morton Co., Ltd.) is provided on both sides of the laminated aluminum foil (“SA30” manufactured by Sumitomo Light Metal Co., Ltd., thickness 9 μm).
L-420 ") was applied to a dry coating amount of 40 mg / m ² and dried.

First, a biaxially stretched syndiotactic polystyrene resin film and an aluminum foil were laminated by a sand lamination method. That is, between the biaxially stretched syndiotactic polystyrene resin film and the aluminum foil,
High-pressure low-density polyethylene (L2 manufactured by Asahi Kasei Corporation)
340 "(melting point: 112 ° C) was extruded into a film so as to have a temperature of 320 ° C directly below the die and a thickness of 15 µm, and a biaxially stretched syndiotactic polystyrene resin film and an aluminum foil were laminated. Next, on the opposite side of the aluminum foil on which the biaxially stretched syndiotactic polystyrene resin film is laminated, a high-pressure low-density polyethylene (“L234” manufactured by Asahi Kasei Kogyo Co., Ltd.) is used as an unstretched polyolefin resin film.
0 ”, melting point 112 ° C), temperature directly below the die 320 ° C, thickness 3
A heat-seal layer was formed by extruding a film at 0 micron. The heat-sealing layers of the obtained laminated film were combined to form a four-sided sealed bag. This bag has sufficient heat-sealing strength, has good appearance without wrinkles on the heat-sealing surface, and is easily torn by hand from any position of the heat-sealing line in a direction almost perpendicular to the heat-sealing line. I was able to open it.

[0039]

Example 5 The above syndiotactic polystyrene was replaced with a general-purpose polystyrene (“Stylon 6” manufactured by Asahi Kasei Corporation).
85 ") so as to be 30% by weight, and extruded with an extruder in the same manner as in Example 4 to prepare a 0.3 mm raw sheet. Using a biaxial stretching machine, the sheet was simultaneously biaxially stretched at a stretching temperature of 115 ° C. and three times in the machine and transverse directions to obtain a 33 micron thick biaxially stretched syndiotactic polystyrene film. Of the resulting film,
The ORS was 22 kg / cm ² in both the vertical and horizontal directions. A laminate was formed in the same manner as in Example 4 using the obtained film. Next, the heat-sealing layers of the obtained laminated film were combined with each other to form a four-sided sealed bag. This bag has sufficient heat-sealing strength, has good appearance without wrinkles on the heat-sealing surface, and is easily torn by hand from any position on the heat-sealing line in a direction almost perpendicular to the heat-sealing line. I was able to open it.

[0040]

Example 6 The laminate side of the biaxially stretched syndiotactic polystyrene film of Example 4 was subjected to a discharge treatment, and an adhesive (“Seika Bond A-342” manufactured by Dainichi Seika Co., Ltd.,
An aluminum foil (“SA30” manufactured by Sumitomo Light Metal Co., Ltd., thickness: 7 μm) was dry-laminated using “Seika Bond C-60”. Next, on the opposite side of the aluminum foil on which the biaxially stretched syndiotactic polystyrene-based film was laminated, a non-stretched polypropylene film ("Pyren Film-CT", manufactured by Toyobo Co., Ltd., thickness 25 μm, melting point 138) was subjected to discharge treatment on the lamination side. C.) was dry-laminated using an adhesive (“Seika Bond E-287” and “Seika Bond C-28” manufactured by Dainichi Seika Co., Ltd.) to obtain a laminated film. The heat-sealing layers of the obtained laminated film were combined to form a four-sided sealed bag. This bag has sufficient heat-sealing strength, has good appearance without wrinkles on the heat-sealing surface, and is easily torn by hand from any position of the heat-sealing line in a direction almost perpendicular to the heat-sealing line. I was able to open it.

[0041]

Comparative Example 4 Instead of the biaxially stretched syndiotactic polystyrene-based film of Example 4, a biaxially stretched general-purpose polystyrene-based film (“OPS film GM” manufactured by Asahi Kasei Kogyo Co., Ltd., thickness: 20 μm, vertical ORS: 15 kg) /
cm, transverse direction ORS 7 kg / cm), and a laminated film was obtained in the same manner as in Example 4. The heat seal layers of the obtained laminated film were combined and heat-sealed, but wrinkles were observed on the seal surface.

[0042]

Comparative Example 5 Instead of a biaxially stretched syndiotactic polystyrene film, a biaxially stretched polyethylene terephthalate film ("S-25N" manufactured by Unitika Ltd.) was used.
C ", a thickness of 25 microns), and a laminated film was obtained in the same manner as in Example 1. It was difficult to easily open the laminated film obtained by heat sealing together the heat seal layers.

[0043]

Comparative Example 6 Same as Example 4 except that a biaxially oriented polypropylene-based film (“OPU-1” manufactured by Tosello Co., Ltd., 25 μm in thickness) was used instead of the biaxially oriented syndiotactic polystyrene-based film. To obtain a laminated film. It was difficult to easily open the laminated film obtained by heat sealing together the heat seal layers.

[0044]

The bag of the present invention has the effect that the bag can be easily torn straight and tear open in the intended direction without making a cut in the tearing area or applying special processing to the outer edge. In addition, the seal surface has no wrinkles and is excellent in appearance. Furthermore, when an aluminum foil is placed between the biaxially oriented polystyrene film and the unstretched polyolefin film, it is easy to cut in advance without tearing or apply special processing to the outer edge. It has the effect of being able to tear open by hand in a straight line in the intended direction, has excellent gas barrier properties, and has excellent appearance without wrinkles on the sealing surface. The above-described effects are useful effects when, for example, a small amount of an article requiring a finished appearance is packaged in pharmaceuticals, foods, and the like.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an easily opened packaging bag according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Packaging bag 2 Heat seal wire

Claims (2)

[Claims] 1. A laminated film containing a biaxially oriented polystyrene resin film having a thickness of 10 to 60 μm and an unstretched polyolefin resin film having a thickness of 10 to 80 μm, and a biaxially oriented polystyrene resin film is bagged. The unstretched polyolefin-based resin film is positioned inside the bag on the outside of the bag, and the width is 3
A packaging bag which is heat-sealed so that a heat seal line of 10 to 10 mm is located, wherein the biaxially oriented polystyrene resin film is a biaxially oriented syndiotactic polystyrene film. 2. An aluminum foil having a thickness of 3 to 70 μm is provided between a biaxially oriented polystyrene resin film having a thickness of 10 to 60 μm and an undrawn polyolefin resin film having a thickness of 10 to 80 μm. The laminated film is placed such that the biaxially stretched polystyrene resin film is positioned outside the bag and the unstretched polyolefin resin film is positioned inside the bag. A packaging bag heat-sealed so that a sealing line is positioned, wherein the biaxially stretched polystyrene resin film is a biaxially stretched syndiotactic polystyrene film.