JP3306463B2 - Easy-open transparent bag with oxygen barrier properties - Google Patents

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 and, more particularly, to a bag having oxygen-blocking properties, being transparent and having easy-openability.

[0002]

2. Description of the Related Art Conventionally, packaging bags are made of various materials such as plastic films, papers, aluminum foils, etc., and have various properties such as strength, gas barrier property, water vapor barrier property and heat sealing property. Development has been performed one after another aiming at something excellent. However, the strength of the packaging material and the excellent heat sealability, from a different perspective,
This also causes difficulty in opening the bag, and there is a demand for a bag having strength, barrier properties, heat sealing properties, etc., and easy opening properties. Various techniques have been proposed for easy opening of packaging materials such as laminated materials. For example, a V, I, U-shaped notch or the like can be used to impart openability, a technique for imparting openability by attaching a small flaw to the outer end of the sealing position, or a linear or other scratch or perforation on the base material. After attaching, a technology to laminate with an intermediate layer such as a gas barrier layer or a sealant layer, a technology to use a uniaxially stretched plastic film as a part of the laminated material, a technology to make the tear direction constant, aluminum, etc. under the base material with the laminated material The metal foil is laminated, and a groove is formed in the base material on the surface by laser processing, and the openability along the groove is provided.

[0003]

However, there are various problems in the prior art as described above. For example,
In the use of a notch and a technique for imparting openability by attaching a small scratch to the outer end of the seal position, it is possible to give a trigger at the time of opening, but the tearing direction after the start of opening can not be specified at all, especially In the packaging of fluids such as liquids and powders / granules, the direction is shifted with the progress of tearing,
There is a problem of spilling the contents.

In a method in which a substrate film is linearly scratched or perforated and then bonded to a barrier layer or a sealant layer, for example, if a conventionally known dry lamination method is used, a perforation such as a perforation may be formed. There is a problem that the adhesive oozes through, and the gap is filled with the adhesive, or the laminated film wound up by the adhesive that oozes out on the opposite side adheres to the front and back, and the packaging material that can be used There is a disadvantage that the bonding method itself is limited. In the technique of using a uniaxially stretched plastic film as a part of the laminated material to keep the tearing direction constant, the tearing direction is limited to a straight line in one direction, and the packaging material strength and the like are determined by heat history such as retort processing. There is a disadvantage that the tearability is reduced.

[0005] On the other hand, the technique of providing a kerf in a base film by laser processing to impart openability along the kerf compensates the above-mentioned drawbacks, and provides a kerf after complete lamination. In addition, there is an advantage that the cut groove can be formed in an arbitrary shape by a laser. But,
When applied to a bag of a laminated material having oxygen barrier properties even in this method, for example, it is important that the layer having oxygen barrier properties to be laminated below the base film is a layer that is not processed by laser. Conventionally, it is only known to use an aluminum foil layer as a packaging material, and application to a transparent bag having oxygen barrier properties was impossible.

Accordingly, the present invention solves the above-mentioned problems, and has excellent performance in that it has oxygen barrier properties, is transparent, has stable easy-openability, and is convenient in use. It is intended to provide a packaging bag.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted various studies and as a result, used a transparent base material film cut by a laser as the outermost layer as the material of the bag. Using a laminated film in which an oxygen-blocking resin layer and a heat-adhesive resin layer that are transparent and not cut by a laser are sequentially laminated underneath, a continuous film for irradiating laser light from the base film side to impart easy-opening properties. Alternatively, by providing discontinuous kerf lines in the base film layer, a solution that can be solved was obtained, and the present invention was completed.

[0008] That is, the invention of claim 1 is an easy-open package comprising a laminated film in which a transparent base film is the outermost layer, and an oxygen-blocking resin layer and a heat-adhesive resin layer are sequentially laminated on one surface thereof. In the transparent bag, the surface of the opening of the easy-opening transparent bag has at least one continuous or discontinuous laser cut groove corresponding to a line to be cut at the time of opening. The material film is made of a material that is cut by a laser, and the oxygen-blocking resin layer and the heat-adhesive resin layer are made of a material that is not cut by the laser. .

According to a second aspect of the present invention, the laser is a carbon dioxide laser, wherein the easy-opening transparent bag having an oxygen-blocking property is provided. The invention according to claim 3 is characterized in that the oxygen-blocking resin layer is an ethylene-vinyl alcohol copolymer resin layer, and the oxygen-blocking easily-openable transparent bag according to claim 1 or 2 is provided. Become.

[0010]

In the present invention, a carbon dioxide laser having a wavelength of 10.6 μm is suitably used as the laser.
That is, the present invention is based on the use of the difference in absorption of a carbon dioxide laser into a packaging material. Among various kinds of lasers, for example, a laser in an ultraviolet region such as an excimer laser has a strong absorption for almost all general transparent flexible packaging materials, so that a selective difference in absorption cannot be used. Lasers in the visible to near-infrared range, such as argon ion lasers, semiconductor lasers, and YAG lasers, hardly absorb general transparent packaging materials and are unsuitable for processing in the present invention.

The carbon dioxide laser emits infrared light having a wavelength of 10.6 μm, and the light having this wavelength is absorbed by a specific packaging material, for example, a film of polyester, nylon, polycarbonate, cellophane or the like. Therefore, by condensing the carbon dioxide laser light and irradiating these film surfaces, the irradiated part of the film can be removed by heat generation, melting, mist or heat generation, decomposition, incineration, etc. Although it can be processed, it is difficult to process because it is transmitted through a film of polyethylene, polypropylene, or the like, and absorbs little. Therefore, by laminating the absorbing material and the non-absorbing material and then irradiating the carbon dioxide laser, it is possible to selectively cut only the absorbing layer.

The easy-opening transparent bag having oxygen barrier properties of the present invention is usually composed of a laminated film of three or more layers. The outermost substrate film is a layer that provides a mechanical strength and various resistances to the laminated film, and can be processed by a carbon dioxide laser, and is provided with a kerf as a trigger for easy opening and a guide for tearing at the time of opening. Yes, the above-mentioned films of polyester, nylon, polycarbonate, cellophane and the like can be used effectively.

The intermediate oxygen-blocking resin layer is a layer having an oxygen-blocking property and not processed by laser. As such a layer, an ethylene-vinyl alcohol copolymer resin film can be suitably used. The ethylene content of the ethylene-vinyl alcohol copolymer resin is preferably 25 to 50 mol%, and more preferably 30 to 45 mol%, in terms of the balance between oxygen barrier properties and non-workability by laser.
Molar% is more preferred. When the ethylene content is lower than this range, the oxygen barrier properties of the film itself are improved, but the laser absorption is increased, and the film is easily damaged, which is not preferable. On the other hand, when the ethylene content is higher than this range, the film is less susceptible to the effects of laser processing, but is not preferable because the oxygen barrier properties of the film itself decrease.

Usually, as the transparent film having oxygen barrier properties, a polyvinylidene chloride (PVDC) film or a film obtained by coating PVDC on another film such as a polyester film or a polypropylene film, a polyvinyl alcohol (PVA) film, In addition to acrylonitrile copolymer resin film, ethylene-vinyl alcohol copolymer resin film, biaxially stretched film of crystalline polyamide obtained by condensation polymerization of meta-xylene diamine and adipic acid, and inorganic vapor-deposited films such as silica and alumina It is used. Among these, an ethylene-vinyl alcohol copolymer resin film that has oxygen barrier properties and can be suitably used as a layer that is not processed by laser is a kerf because other materials have carbon dioxide gas laser absorptivity. At the time of processing, the kerfs are removed together with the base film, which causes a decrease in oxygen barrier properties from this portion, which is not preferable. Further, in the case of a PVDC coat film or an inorganic vapor-deposited film, the PVDC coat film or the vapor-deposited film is destroyed by the irradiation of the carbon dioxide gas laser, and the oxygen barrier property is deteriorated.

The innermost thermo-adhesive resin layer has heat sealing properties and is not processed by a carbon dioxide laser. Materials that can be used for this layer include polyethylene,
In addition to polypropylene, various polyolefin-based resins including ethylene-vinyl acetate copolymer resin and the like can be mentioned, and they can be freely selected and used according to the use or required performance. This layer is laminated with the intermediate layer by a method in which the above resin is formed into a film in advance and then dry-laminated using an adhesive, or a method in which another adhesive resin is melt-extruded and extruded and laminated as an adhesive layer. However, depending on the case, the resin may be melted and directly extruded onto the intermediate layer to form a laminate.

As the overall laminating method for laminating each of the above-mentioned base film, oxygen barrier resin layer and heat-adhesive resin layer, in addition to a conventionally known dry lamination method, an adhesive resin such as polyethylene is used. An extrusion lamination method (so-called sandwich lamination method) in which the layers are laminated via a multilayer or a co-extrusion method with multiple layers can be used, and the most suitable method can be selected according to the use and performance of the bag. Further, in the present invention, the shape to be cut by the carbon dioxide gas laser is arbitrary, and it can be processed freely, such as a continuous line or a discontinuous line such as a perforation, such as a straight line or a curved line.
If necessary, a notch can be used at the end of the kerf line. And also about the shape of the bag obtained by bag-making the laminated film created as described above,
There is no particular limitation, and the present invention can be applied to any type such as a pillow type, a gusset type, a stick package, and a standing pouch, in addition to the conventionally known three-side seal and four-side seal types.

[0017]

The laminated film as described above is used for the easily-openable transparent bag having oxygen barrier properties of the present invention.
Each layer of the laminated film is made of a transparent material, and after laminating each layer, only the outermost substrate film can be selectively cut by laser light. Therefore,
The work of laminating and kerf processing is facilitated, and the kerf line that provides easy opening without damaging the oxygen barrier resin layer can be provided in any shape, and is transparent and has excellent visibility of the contents. In addition, an easily-openable bag excellent in oxygen barrier properties can be easily obtained.

[0018]

The present invention will be described more specifically with reference to the drawings, examples and comparative examples. FIGS. 1 and 2 are schematic cross-sectional views showing one embodiment of the configuration of the laminated film used for the easily-openable transparent bag having oxygen barrier properties of the present invention.
That is, FIG. 1 shows a substrate film 1 as an outermost layer, and an oxygen-blocking resin layer 2 and a heat-adhesive resin layer 3 on one surface thereof using an adhesive 4 by a conventionally known dry lamination method. The structure which laminated | stacked sequentially is shown. FIG.
The substrate film 1 is used as the outermost layer, and the oxygen-blocking resin layer 2 and the heat-adhesive resin layer 3 are bonded on one surface to the adhesive resin layer 5a or 5a, respectively, by a conventionally known extrusion lamination method. 5B shows a configuration in which the layers are sequentially stacked via the layers 5b. In the case of laminating using the extrusion lamination method as in the present embodiment, after laminating the base film 1 and the oxygen barrier resin layer 2 by the extrusion lamination method via the adhesive resin layer 5a, The resin of the heat-adhesive resin layer 3 may be directly extruded and coated on the oxygen-blocking resin layer 2 without using the adhesive resin layer 5b.

FIG. 3 is a schematic plan view showing one embodiment of the easily-openable transparent bag having oxygen barrier properties of the present invention. The form of the bag is an example of a four-side sealed bag, and four sides around the bag are sealed by the heat seal portion 7. The surface of the bag is the base material film 1 as the outermost layer of the laminated film, and a cut groove 6 by a laser is provided on the surface near one seal portion which becomes an opening. FIG. 4 is a cross-sectional view of an essential part for explaining one example of the vicinity of the opening of the easily-openable transparent bag having oxygen barrier properties according to the present invention. In FIG. 4, the kerf 6 forming the opening of the bag is provided at a position near the heat sealing portion 7 on one side of the bag and inside the sealing portion, on each surface of the upper and lower two laminated films forming the bag, This is a structure in which upper and lower cut grooves 6 are provided so as to overlap.

Example 1 A substrate film having a thickness of 1
5 μm biaxially stretched nylon film [Emblem RT
Unitika Co., Ltd.] and an ethylene-vinyl alcohol copolymer resin film [EVAL EF-RT Co., Ltd.] having a thickness of 15 μm as an oxygen barrier resin layer on one surface.
Made by Kuraray Co., Ltd.)
μm unstretched polypropylene film [Pyren T-1
146, manufactured by Toyobo Co., Ltd.], a two-component reactive urethane-based adhesive was applied at a coating amount of 3 g / m ² (solid content) by a well-known dry lamination method, and they were sequentially bonded to each other. A laminated film for oxygen-blocking transparent bags for easy opening was prepared. The bonding surface of the unstretched polypropylene film was a corona discharge treated surface. Configuration of laminated film Biaxially stretched nylon film (15 μm) / adhesive (3 g
/ M ² ) / ethylene-vinyl alcohol copolymer resin film (15 μm) / adhesive (3 g / m ² ) / unstretched polypropylene film (60 μm)

Example 2 A substrate film having a thickness of 12
μm biaxially stretched polyester film [Ester E51
00 manufactured by Toyobo Co., Ltd.] and an ethylene-vinyl alcohol copolymer resin film (manufactured by EVAL EF-XL Kuraray Co., Ltd.) having a thickness of 12 μm as an oxygen barrier resin layer.
Then, using a non-stretched polyethylene film having a thickness of 30 μm [moretech 0238N manufactured by Idemitsu Petrochemical Co., Ltd.] as the heat-adhesive resin layer, polyethylene [Mirason 11 manufactured by Mitsui Petrochemical Industry Co., Ltd.] by a known extrusion lamination method. Was extruded as an adhesive resin layer with a thickness of 10 μm, and the three types of films were sequentially laminated to prepare a laminated film of Example 2 for an easy-opening transparent bag having oxygen barrier properties. In the case of extrusion lamination, the biaxially stretched polyester film surface is treated with a corona discharge treatment, and an isocyanate-based anchor coat is applied. The isocyanate-based anchor coat is also applied to the bonding surface of the ethylene-vinyl alcohol copolymer resin film. And laminated. Configuration of laminated film Biaxially stretched polyester film (12 μm) / polyethylene (10 μm) / ethylene-vinyl alcohol copolymer resin film (12 μm) / polyethylene (10 μm)
/ Unstretched polyethylene film (30μm)

Comparative Example 1 In the structure of the laminated film of Example 1, the ethylene-vinyl alcohol copolymer resin film (EVAL EF-RT) used for the oxygen barrier resin layer was used.
Only the polyvinylidene chloride film (thickness: 15 μm) was replaced with a polyvinylidene chloride film (Saran UB, thickness: 15 μm, manufactured by Asahi Kasei Kogyo Co., Ltd.). A laminated film for an openable transparent bag was prepared. Configuration of laminated film Biaxially stretched nylon film (15 μm) / adhesive (3 g
/ M ² ) / Polyvinylidene chloride film (15 μm) /
Adhesive (3 g / m ² ) / Unstretched polypropylene film (60 μm)

(Comparative Example 2) In the construction of the laminated film of Example 2, only the ethylene-vinyl alcohol copolymer resin film (thickness 15 μm) used for the oxygen-barrier resin layer was replaced with an inorganic vapor-deposited polyester film (thickness 12 μm).
Instead of [Tech Barrier U manufactured by Mitsubishi Kasei Polytech Co., Ltd.], all other processes were performed in the same manner as in Example 2 to prepare a laminated film for an easily-openable transparent bag having oxygen barrier properties of Comparative Example 2. Configuration of laminated film Biaxially stretched polyester film (12 μm) / polyethylene (10 μm) / inorganic vapor-deposited polyester film (12 μm) / polyethylene (10 μm) / unstretched polyethylene film (30 μm)

(Cut groove processing and bag making by laser)
Examples 1 and 2 and Comparative Examples 1 and 2 obtained as described above
Using a laminated film of the above, in order to create an easy-opening transparent bag having oxygen barrier properties, after performing kerf processing with a carbon dioxide gas laser in the following method, using a part thereof, the film on both sides Each side seal type bag (see FIG. 3) having a kerf at an overlapping position is subjected to an impulse seal for 20 bags.
Created individually. Laser kerf processing method Laser device manufactured by Coherent Corporation of the United States, Diamond
Using a carbon dioxide laser with an output of 150 W from the base film side of each laminated film for a pulse duration of 20 μm.
The light was condensed to a spot diameter of 120 μm repeatedly at 10 KHz for 2 seconds and continuously irradiated with pulses, and the laminated film was moved at 100 m / min to form a linear cut groove.

(Test and Evaluation Results) (1) Evaluation of Easy Opening by Cut Groove Processing Each bag of the four-sided seal type having cut grooves formed by the above-described method was used as a sample, and the bag was manually cut from the end of the cut groove line. After tearing and opening, the cutting direction and easiness of cutting were evaluated, and evaluation of easy-opening property was made. As a result, in each of the samples of Examples 1 and 2 and Comparative Examples 1 and 2, the cutting direction was torn along the kerf line, and the easiness of cutting was good without any problem.

(2) Observation of depth of kerf processing and measurement of oxygen permeability Using the laminated films of Examples 1 and 2 and Comparative Examples 1 and 2 subjected to kerf processing by the above-described method as samples, kerf portions The cross section was observed under a microscope and the depth was shown in Table 1.
In addition, a laser non-irradiated part and a part cut by laser irradiation of each sample were sampled and subjected to JIS K71.
Oxygen permeability was measured by the gas permeability test method for plastic films and sheets of Method 26 (Method B), and the results are shown in Table 1.

[0027]

[Table 1]

As shown in Table 1, in the laminated films of Examples 1 and 2, only the base film layer was cut by carbon dioxide laser processing, and the oxygen-blocking resin layer and the heat-adhesive resin layer were formed. Was undamaged. Accordingly, no decrease in oxygen barrier properties due to carbon dioxide laser processing was observed for the measured values of oxygen permeability. On the other hand, in the laminated films of Comparative Examples 1 and 2, the groove was cut to the oxygen-blocking resin layer together with the base film by carbon dioxide laser processing, and the oxygen-blocking property was significantly reduced as compared to before the processing. .

[0029]

According to the first aspect of the present invention, the easily openable transparent bag having oxygen barrier properties has a transparent base film as the outermost layer, and has one side provided with an oxygen barrier as described above in detail. In the easy-opening transparent bag formed of a laminated film in which an adhesive resin layer and a heat-adhesive resin layer are sequentially laminated, the surface of the opening of the easy-opening transparent bag has at least one line corresponding to a line to be cut at the time of opening. The book has a continuous or discontinuous laser cut groove, and the base film is made of a material that is cut by a laser, and the oxygen-blocking resin layer and the heat-adhesive resin layer are made of a material that is not cut by the laser. It is characterized by having. By adopting such a configuration, the laminated film can be made of only a transparent material, so that the bag itself is transparent and has excellent visibility of the contents, and the kerf for easy opening is irradiated with laser light. By this, it is possible to selectively and stably provide only the outermost base film without damaging the oxygen-blocking resin layer and the heat-adhesive resin layer, so that the oxygen-blocking property is excellent and the kerf line is opened when opened. Thus, there is an effect that a bag which can be easily torn and opened by being provided with high productivity can be provided.

According to a second aspect of the present invention, in the first aspect of the present invention, a carbon dioxide gas laser is used as a laser for forming the kerf, thereby ensuring that only the base film in the laminated film is kerfed. It can be processed and has the effect of obtaining the performance of the bag more stably. The invention of claim 3 is the invention of claim 1 or 2, wherein the oxygen-blocking resin layer uses an ethylene-vinyl alcohol copolymer resin, whereby the oxygen-blocking resin layer is irradiated with laser light. Better resistance to
This has the effect of maintaining excellent oxygen barrier properties and stabilizing the ease of opening by the kerf line.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a configuration of a laminated film used for an easily-openable transparent bag having oxygen barrier properties of the present invention.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the configuration of the laminated film used for the easily-openable transparent bag having oxygen barrier properties of the present invention.

FIG. 3 is a schematic plan view showing one embodiment of an easily-openable transparent bag having oxygen barrier properties of the present invention.

FIG. 4 is a cross-sectional view of a main portion illustrating an example of the vicinity of an opening of the easily-openable transparent bag having oxygen barrier properties according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base film 2 Oxygen barrier resin layer 3 Thermal adhesive resin layer 4 Adhesive 5a Adhesive resin layer 5b Adhesive resin layer 6 Cut groove 7 Heat seal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B65D 33/00 B65D 65/30 B65D 77/30 B65D 81/30

Claims (3)

(57) [Claims] 1. An easy-opening transparent bag comprising a laminated film in which a transparent substrate film is used as an outermost layer, and an oxygen-blocking resin layer and a heat-adhesive resin layer are sequentially laminated on one surface thereof. The surface of the opening of the transparent transparent bag has at least one continuous or discontinuous laser cut groove corresponding to the line to be cut at the time of opening, and the base film is cut by the laser. An easily-openable transparent bag having oxygen-blocking properties, wherein the material is such that the oxygen-blocking resin layer and the heat-adhesive resin layer are not cut by a laser. 2. The easy-opening transparent bag having oxygen barrier properties according to claim 1, wherein the laser is a carbon dioxide laser. Peelable transparent bag having oxygen barrier properties according to claim 1 or 2, wherein the vinyl alcohol copolymer resin layer - wherein the oxygen barrier resin layer is ethylene.