JP2898897B2 - Gas barrier soft packaging bag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible packaging bag having high gas barrier properties and easy to incinerate (no pollution) without using aluminum foil.

[0002]

2. Description of the Related Art The diversification of food and the change in eating habits associated with the remarkable advancement of women in society, the concentration of population in cities, the diversification of working hours, the transition to a nuclear family, the aging society, and the like, have led to a change in "delicious" There is a growing demand for easy access to things at all times. As a result, there is a strong demand for long and delicious foods, which is one of the reasons for the need for barrier packaging materials. For example, fried snacks such as potato chips are very susceptible to oxidation. The oxidation rate is proportional to the oxygen concentration, and the oxidation rate increases exponentially as the temperature increases. Package 184 g of potato chips in a bag of potato chips in a size of 22 cm × 32 cm, set the shell life at 25 ° C. and 65% RH to 6 months, and suppress the oxygen permeation amount for 6 months to 10 ppm or less. Then, the oxygen permeability of the pouch is 0.3c
c / m ² · 24 hrs or less. Currently, aluminum foil is mostly used as a soft packaging bag to achieve this purpose.

[0003] As described above, a paper soft packaging bag requiring oxygen gas barrier properties is manufactured by laminating an aluminum foil having a thickness of about 7 µm together with paper, a plastic film, and the like. It is known that aluminum reacts with the refractory material of incinerators and shortens the life of incinerators. In addition to the problem of non-degradability even in landfills, recently aluminum itself is harmful to humans ( For example, Alzheimer's is warned. Therefore, there is a strong demand for a soft packaging bag having a configuration in which aluminum foil is removed from a flexible packaging bag for foods and the like.

[0004] Fig. 2 shows an example of the configuration of a conventional gas barrier soft packaging bag containing aluminum foil.
The polyethylene layer A / the adhesive layer B / the aluminum foil layer C / the polyethylene layer D / the paper layer E are laminated in this order from the inside to the outside of the bag. By laminating the aluminum foil layer C in this manner, oxygen gas barrier properties and light shielding properties are maintained.

[0005] In order to maintain the same oxygen gas barrier property except for the aluminum foil from such a gas barrier flexible packaging bag structure, for example, a vapor-deposited film of various metals, saponified ethylene-vinyl acetate copolymer (EVOH), etc. The use of a gas barrier resin as a gas barrier layer has been proposed. However, in the case of a metal vapor-deposited plastic film, pinhole formation is inevitable unless the vapor deposition amount is increased, and thick vapor deposition increases costs. Also, when a barrier resin such as EVOH is used, the oxygen gas barrier property is greatly affected by the environmental humidity, and when the humidity is high, the gas barrier property is greatly reduced. Even if it can be used, it is insufficient as a light packaging bag that can be stored at room temperature, and its improvement has been desired.

On the other hand, a packaging material using a plastic layer having a silicon oxide vapor-deposited thin film layer on at least one side instead of the aluminum foil in the laminate has the above object in view of only the oxygen gas barrier property. To achieve. In this case, the thickness of the vapor deposition layer may be as thin as several hundred angstroms, so that the plastic layer (PET, OPP, etc.) for imparting strength as a substrate can be recycled with the vapor deposition thin film layer attached. It is.

However, when a flexible packaging bag is manufactured and used, a silicon oxide thin film layer formed on a plastic film (PET) by vapor deposition or the like is vulnerable to elongation and bending as it is. At the time of packaging, the packaged product is easily broken or cracked even by a shock in handling the packaged product, and thus cannot maintain a stable barrier property as a soft packaging bag.

[0008] In a soft packaging bag produced from a laminate containing no aluminum foil, the oxygen gas barrier property is insufficient or difficult to handle, and the content of the content which requires storage at room temperature is poor. It is not preferable as a flexible packaging bag. Particularly, in a soft packaging bag in which a silicon oxide thin film layer is deposited on a plastic film, since the thin film layer is extremely brittle, for example, by heat shock when an adhesive layer such as polyethylene is provided for bonding with a paper layer, or When a flexible paper bag made of paper is manufactured from the laminate, cracks and pinholes are easily generated in the thin film due to external stress, a high degree of barrier property cannot be maintained, and a normal temperature storage flexible bag using aluminum foil is used. There is a problem in practical use as a packaging material requiring such a stable barrier property.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a soft packaging bag not using aluminum foil, which has a high oxygen gas barrier property similar to a soft packaging bag using aluminum foil for storage at room temperature. It is an object of the present invention to provide a soft packaging bag which is hardly damaged or cracked in a barrier layer due to bending, mechanical impact, thermal impact, or the like in bag making / packaging transportation and can be incinerated in an incinerator.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a plastic layer 1 which can be heat-sealed in order from an inner layer to an outer layer.
A plastic layer 2 for imparting strength / a vapor-deposited silicon oxide thin film layer / a hydroxyl group-containing thermoplastic resin layer / a paper layer, and a laminated body mainly comprising a paper layer. The above object was achieved by developing a packaging bag. In the present invention, the heat-sealable plastic layer 1 is a heat-sealable thermoplastic resin layer such as an extrusion-coatable low-density polyethylene resin, a high-density polyethylene resin, a polypropylene resin, and an ethylene-vinyl acetate copolymer. The thickness is about 10-60μm
Formed on the digit. The plastic layer 2 for imparting strength is a layer made of a strong film such as PET, ON, and OPP, and silicon oxide is vapor-deposited on this plastic film before use. The silicon compound is usually represented by the general formula SiO _x (where x = 1.4 to 1.9 is common), and the thickness of the deposited film is about 20.
It is of the order of 0-2000 ° and is usually deposited on two layers of plastic.

Hydroxy group-containing thermoplastic resins include EVOH and polyvinyl alcohol (PV) having oxygen barrier properties.
A) or the like, a resin composition containing at least one thermoplastic resin having a large number of hydroxyl groups in the molecule or an unsaponifiable ethylene-vinyl acetate copolymer (unsaponifiable EVA) is used. It is desirable that the amount of unsaponified EVA is at most 99% by weight, preferably 10 to 90% by weight in the resin composition. By blending unsaponified EVA, the flexibility of the hydroxyl-containing thermoplastic resin layer can be further improved. It is said that EVOH and the like have oxygen barrier properties themselves, but such a resin layer alone cannot provide a high oxygen gas barrier property only when used alone.

However, the hydroxyl group in the resin layer and the SiO _x of the silicon oxide vapor-deposited film have a synergistic effect in the barrier property due to the hydrational bond, and the flexibility of the resin is high. eliminating the brittleness of the deposited film, processability of the multilayered body including the SiO _x deposited film is for improving the impact resistance. For this reason, by applying this resin, it is possible to prevent the silicon oxide film from being damaged by thermal stress, mechanical shock, or the like at the time of bag making or at the time of transportation of a packaged product, and to prevent oxygen gas from being damaged. This is for maintaining stable barrier properties. In order to exhibit this function, a thickness of at least 1 g / m ² is required, and from the viewpoint of cost, a maximum thickness of 20 g / m ² or less is preferable.

The paper quality of the paper layer adjacent to the hydroxyl-containing thermoplastic resin layer may be selected according to the purpose of printing or imparting rigidity for maintaining the shape of the bag, and is not particularly limited. Fine paper of about 30 to 80 g / m ² may be used. This can be easily laminated by bonding to a hydroxyl group-containing thermoplastic resin applied to the SiO _x vapor deposition layer.

In the present invention, the outermost layer of the packaging bag is a paper layer. However, in order to impart water resistance, stain resistance, etc., or to enhance the merchantability, the packaging bag is printed, polyethylene, polyvinyl chloride, or the like. Ethylene-vinyl acetate copolymer,
Paper such as extrusion coating or emulsion coating of a resin such as wax may be used, or coating and coating may be performed after bag making.

The present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view of one embodiment of the present invention. In the present invention, each of these layers is heat-sealed from the inner layer to the outer layer of the packaging bag 1 / plastic layer 2 for imparting strength / silicon oxide vapor-deposited thin film layer 2a / hydroxyl group-containing heat This is a soft packaging bag formed by laminating a plastic resin layer 3 and a paper layer 4 in this order. There is no particular limitation on the bag, but in the case of containing contents that are degraded by light or the like, an ultraviolet-cut film layer or an ultraviolet-cut ink layer may be appropriately provided in the laminate.

The production of the laminated soft packaging bag is not limited, but it is convenient to produce it by the following method, for example. That is, first, a silicon oxide thin film layer 2a is formed on one surface of a plastic film 2 such as PET or OPP by a vacuum evaporation method or the like. Next, a hydroxyl group-containing thermoplastic resin solution is applied to the surface of the silicon oxide thin film layer 2a of this film, and the paper is laminated during the wet state to form the hydroxyl group-containing thermoplastic resin layer 3 and the paper layer 4. I do. If necessary, a polyethylene layer 5 is provided by coating a low-density polyethylene on the paper layer surface by melt extrusion, but the wax resin layer 5 can be provided by coating a wax resin. Finally, an adhesive is applied to the other surface of the plastic film 2 and the polyethylene layer 1 is formed by coating low density polyethylene by melt extrusion. The obtained laminate is formed into a soft packaging bag by a conventional method.

[0017]

According to the present invention, the thin film layer of silicon oxide is combined with a hydroxyl group-containing thermoplastic resin in the laminate, so that the barrier effect is substantially the same as that of a conventional soft packaging bag using aluminum foil due to the synergistic effect. In addition to improving the brittleness of the silicon oxide deposited thin film layer and having sufficient moldability, it is also possible to bond it to a paper layer without using adhesive polyethylene etc. Was. The laminate obtained according to the present invention enables automatic bag-making from a winding material, which has been severely bent in a conventional laminate having vacuum-deposited silicon oxide, and was impossible to be made from a bag. There is no problem in sealing and transportation. Of course, because aluminum is not used, it will eliminate pollution, for example, factors such as disposal difficulties (incinerator breakage, landfill difficulties) and Alzheimer's (blurring of the elderly).

[0018]

EXAMPLE Low-density polyethylene layer 1 (30 μm) / PET film layer 2 (12 μm) / silicon oxide vapor-deposited layer 2a (500 °) / hydroxyl-containing thermoplastic resin layer 3 (4 g / m ² ) produced by the above method. ) / Laminated film consisting of paper layer 4 (50 g / m ² )
A bag having a size of 4 cm and a width of 11 cm was prepared by heat sealing to obtain a soft packaging bag for testing. In addition, a laminate was also prepared in which the hydroxyl-containing thermoplastic resin layer 3 was omitted, and a bag was formed in the same manner as above to obtain a comparative example.

A gas barrier property measurement of the packaging bag and a storage test of the contents were carried out, and the results are shown in Tables 1 and 2 below. Table 3 shows the results of the further incineration tests. Gas Barrier Property: Flexible Packaging Bag 1) The flexible packaging bag A of the present invention, a 4: 6 blend of PVA and unsaponified EVA was used as the hydroxyl group-containing thermoplastic resin. 2) Flexible packaging bag B of the present invention, EVOH (partially saponified) 3) Conventional flexible packaging bag, laminate of polyethylene (30 μm) / aluminum foil (7 μm) / polyethylene (15 μm) / paper (50 g / m ² ) Was made. 4) A soft packaging bag without a hydroxyl group-containing thermoplastic resin layer (the hydroxyl group-containing thermoplastic resin layer was removed from the soft packaging bag A of the present invention). Contents, filled with nitrogen (oxygen concentration almost zero). weekly

[Table 1]

Contents preservation test: Soft packaging bag, same as above Contents, sushi (approximately 50 g) After sealing, leave at room temperature and 90% RH for 2 weeks

[Table 2]

Incineration test: Flexible packaging bag, same as above, contents incinerated in empty electric furnace (1000 ° C)

[Table 3]

[0022]

The present invention uses a silicon oxide vapor deposited layer and a hydroxyl group-containing thermoplastic resin layer in place of aluminum foil, and thus has sufficient heat resistance and mechanical resistance. As for production, it can be produced in the same process as aluminum foil, and can be easily post-processed (incinerated, etc.) in packaging bags, and has almost the same barrier properties as conventional soft packaging bags made of aluminum, The soft wrapping bag has a very wide range of application as a package for confectionery and has an extremely high economic effect.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view in which a part of an embodiment of the present invention is cut away.

FIG. 2 is an explanatory sectional view in which a part of a conventional soft packaging bag is cut away.

[Explanation of symbols]

 Reference Signs List 1 polyethylene layer 2 polyethylene terephthalate (PET) layer 2a silicon oxide thin film layer 3 hydroxyl-containing thermoplastic resin layer 4 paper layer 5 polyethylene layer A polyethylene layer B adhesive layer C aluminum foil layer D polyethylene layer or wax resin layer E Paper layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-16441 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65D 81/24 B32B 9/00 B32B 27 / 06 B65D 65/40

Claims (3)

(57) [Claims] 1. A plastic layer that can be heat-sealed in order from an inner layer to an outer layer 1 / a plastic layer for imparting strength 2 / a thin film layer of silicon oxide deposited / a hydroxyl-containing thermoplastic resin layer / a paper layer A gas-barrier soft packaging bag, which is formed by bag-forming a laminate. 2. The gas barrier flexible packaging bag according to claim 1, wherein the plastic layer 2 is a biaxially oriented polyethylene terephthalate film (PET), a biaxially oriented polyamide film (ON) or a biaxially oriented polypropylene film (OPP). 3. The resin composition according to claim 1, wherein the hydroxyl group-containing thermoplastic layer is a saponified product of polyvinyl alcohol and / or an ethylene-vinyl acetate copolymer or an unsaponifiable ethylene-vinyl acetate copolymer. 2. The gas-barrier flexible packaging bag according to 2.