JPH11342559A - Packaging material with gas barrier properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a packaging material with a barrier layer usable in a high humidity atmosphere by forming the barrier layer containing an inorganic layerlike compound and a resin on one of the faces of a plastic film with a specific thickness and a humidity permeability below a specified level. SOLUTION: A barrier layer 2 and a printed layer 3 are laminated on a plastic film 1. In this case, the plastic film 1 to be used is a polypropylene film or the like with 5 g/m<2> or less moisture permeability at 20 μm thickness. In addition, the barrier layer 2 is formed of at least, an inorganic layerlike compound and a resin, and the inorganic layerlike compound to be used is montmorillonite or the like. The resin to be used is polyvinyl alcohol or the like. In this case, the barrier layer 2 is formed by applying a coating solution in about 2-4 divided parts, and the coating build-up is an amount to meet the drying capability of a drying oven for a printing part each time each of the divided parts is applied. Thus it is possible to control the deterioration of the barrier properties to a minimum extent even in a high humidity atmosphere and ease the limitation of a use range and at the same time, manufacture the packaging material continuously and simultaneously with the formation of the printed layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-barrier packaging material exhibiting high barrier properties even in a high-humidity atmosphere.

[0002]

2. Description of the Related Art It has been practiced to apply a gas barrier resin such as polyvinyl alcohol on a plastic film to improve the gas barrier property. As described above, since a large amount of heat is required to apply and form a gas barrier resin to a plastic film, it is difficult to continuously manufacture with a normal gravure printing machine. It is common to use a coating device having a dryer.

[0003] Here, not only the gas barrier resin such as polyvinyl alcohol is applied but also the barrier layer is formed by an application agent to which an inorganic layered compound is added, so that the above-mentioned problem in production can be solved. Was. However, the packaging material on which the barrier layer is formed exhibits high barrier properties in a low-humidity atmosphere, but in a high-humidity atmosphere, the barrier layer once absorbs moisture by a coating agent to which the inorganic layered compound is added. If it does, there is a disadvantage that the function of the moisture-proof property is reduced. Therefore, when using a packaging material having a barrier layer with a coating material to which the inorganic layered compound is added, the atmosphere in which the contents are packaged and stored has to be considered.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to use a packaging material having a barrier layer in a high-humidity atmosphere by using a coating agent to which an inorganic layered compound having a high barrier property is added. The purpose is to:

[0005]

SUMMARY OF THE INVENTION The present invention has a thickness of 20 .mu.m.
A gas barrier packaging material, characterized in that a barrier layer containing an inorganic layered compound and a resin is provided on one surface of a plastic film having a moisture permeability of 5 g / m ² or less.
The invention according to claim 2 is a gas barrier packaging material, characterized in that a barrier layer containing an inorganic layer compound and a resin is provided on the plastic film via an anchor coat layer.

According to a third aspect of the present invention, there is provided a gas barrier packaging material characterized in that the barrier layer is formed by applying the barrier layer many times. The invention according to claim 4 is a gas barrier packaging material, wherein the barrier layer contains a hydrolysis / polycondensation product of a metal alkoxide. The invention according to claim 5 is a gas barrier packaging material, wherein the inorganic layered compound is montmorillonite. The invention according to claim 6, wherein the resin is a water-soluble polymer,
It is a gas barrier packaging material. The invention according to claim 7 is a gas barrier packaging material, characterized in that the water-soluble polymer is polyvinyl alcohol. The invention according to claim 8 is a gas barrier packaging material, characterized in that a printing layer is formed on the barrier layer.
The invention according to claim 9 is a gas barrier packaging material, wherein a sealant layer is formed on the barrier layer via an adhesive layer.

[0007]

FIG. 1 is a sectional view showing an example of a gas barrier packaging material according to the present invention, wherein 1 is a plastic film, 2 is a barrier layer, and 3 is a printed layer. FIG. 2 is a cross-sectional view showing another configuration example, which is a material in which a barrier layer 2 is provided on a plastic film 1 via an anchor coat layer 4. FIG. 3 shows an example in which the material shown in FIG. 2 is used as a packaging material, and has a configuration in which a sealant layer 6 is laminated on a printed layer 3 with an adhesive layer 5 interposed therebetween.

Here, as the plastic film 1, any plastic film having a thickness of 20 μm and a moisture permeability of 5 g / m ² or less can be used. Specifically, a polyolefin film such as polyethylene or polypropylene can be used. Particularly, a stretched polypropylene fill having a multilayer structure is preferred.

The barrier layer 2 is composed of at least an inorganic layer compound and a resin. Examples of the inorganic group compound include a kaolinite group, a smectite group, and a mica group. Among these, smectites such as montmorillonite, hectorite, and saponite are preferable, and a resin is easily taken in between layers of the inorganic layered compound to easily form a complex.
In particular, among these families, montmorillonite is the most excellent in stability and coatability in a molten state.

The resin to be used is not particularly limited as long as it is easily taken in between the layers of the above-mentioned inorganic layered compound, but it is preferable to use a water-soluble polymer. As the water-soluble polymer, polyvinyl alcohol (PVA),
Polyvinylpyrrolidone, starch, methylcellulose,
Examples include carboxymethyl cellulose, acrylic resin, and sodium alginate. In particular, when polyvinyl alcohol (PVA) is used as the coating agent for the gas barrier laminate of the present invention, the gas barrier properties are most excellent. PVA referred to here is generally obtained by saponifying polyvinyl acetate, and has several tens% of acetic acid groups remaining.
It includes everything from so-called partially saponified PVA to completely saponified PVA in which only a few percent of acetic acid groups remain, and is not particularly limited.

The barrier layer of the present invention may have a composition further containing a hydrolysis / polycondensation product of a metal alkoxide. This metal alkoxide is a compound represented by the following general formula, M (OR) _n , where M is a metal, R is an alkyl group, and n is a coordination number of an alkoxy group. Preferably, M is selected from the group consisting of Si, Ti, Ar and Zr, and R is selected from a methyl group and an ethyl group. In particular, tetraethoxysilane [Si (OC ₂ H _{5) 4],} the use of such triisopropoxyaluminum _{[Al (O-2'-C 3} H 7) 3 ], alkoxide hydrolysis products, water-based It is preferable because it is relatively stable in a solvent.

Each of the above-mentioned components can be added to the coating agent alone or in a combination of several components. Further, as long as the barrier properties of the coating agent are not impaired, isocyanate compounds, silane coupling agents, dispersants, and stabilizers Known additives such as a viscosity modifier and a colorant can be added.

For example, an isocyanate compound to be added to a coating agent has two or more isocyanate groups (NCO groups) in its molecule, such as tolylene diisocyanate (TDI), triphenylmethane triisocyanate (TTI), There are monomers such as tetramethylxylene diisocyanate (TMXDI), and polymers and derivatives thereof.

As a method for applying the coating agent, conventionally known means such as a dipping method, a roll coating method, a screen printing method, and a spray method are used. Although the thickness of the film varies depending on the type of the coating agent, the thickness after drying may be in the range of about 0.01 to 100 μm. It is desirable that the thickness be 50 μm.

The printing layer 3 is formed of an ink that can be used by a usual gravure printing method. Further, for the anchor coat layer 4, a coating agent selected from the group consisting of imine, urethane, butadiene, and titanium oxide is used.

For the sealant layer 6, a resin film having heat sealing properties such as polyethylene, polypropylene, ethylene copolymer, and saturated polyester can be used. In particular, when heat resistance and moisture resistance are required, It is preferable to use an unstretched polypropylene film. In addition, when a polyolefin synthesized using a metallocene catalyst is used, adhesion of resin odor to an article to be packaged can be reduced. This sealant layer 6
It can be formed by a method of laminating via an adhesive layer 5 made of a two-liquid or one-liquid urethane adhesive, or a method of laminating by extruding and coating a molten resin via an adhesive layer 5 made of an anchor agent. .

Next, the manufacturing method of the present invention will be described. The continuous plastic film is unwound, an anchor coat agent is applied and dried first to form an anchor coat layer, and then a barrier agent is applied and dried in the next step to form a barrier layer. Then, in the printing section, apply printing ink and dry,
A printing layer is formed, and a packaging material having gas barrier properties is manufactured.

Here, it is preferable that the barrier layer is applied in two to four times to have a predetermined thickness. By setting the coating amount to match the drying capacity of the drying oven of each printing unit, it is possible to form without lowering the manufacturing speed. The coating amount per one time is 1 to 10 g / m ^{2 in} a wet state (0.01 to 1.0 g in a dry state).
/ M ² ), and the coating amount of the entire barrier layer in a dry state is in the range of 0.1 to ² g / m ² , preferably 0.3 to 1.0 g / m ² . It is preferable to set the range.

[0019]

<Example 1> Gravure printing machine (8) manufactured by Nakajima Seiki
Color machine) on a stretched polypropylene film (hereinafter referred to as OPP) having a thickness of 22 μm and corona-treated on one side and having a moisture permeability of 3 to 5 g / m ² (hereinafter referred to as OPP), and a urethane-based anchor coat on the corona-treated side in the first printing section. After applying and drying an agent to form an anchor coat layer, a barrier agent having the following composition is applied and dried in the second printing section and the third printing section, and then dried.
A barrier layer of ² g / m ² was formed. Next, a non-stretched polypropylene film (hereinafter referred to as CPP) having a thickness of 60 μm was bonded via a two-component curable urethane-based adhesive to produce a gas barrier packaging material. In addition, the drying oven of the printing machine was the heating method described above, the air volume was 50 m ³ / min, and the coating speed of the printing machine was 80 m / min. And
The oxygen permeability and water vapor permeability of the obtained gas barrier material were measured. Table 1 shows the results. In addition, a bag is manufactured with the CPP side of the packaging material as the inner surface, and the humidity on the OPP side (outside) is set to 30 ° C. and 90% atmosphere, and the oxygen permeability when the relative humidity in the bag is changed is measured. did. Table 2 shows the results.

(Composition of barrier agent) Montmorillonite was added to a 5% by weight aqueous solution of polyvinyl alcohol (PVA).
PVA and montmorillonite were mixed such that the weight ratio was 1: 1.

Comparative Example 1 An OPP (thickness: 20 μm) (trade name: EG10, manufactured by Daicel Chemical Industries, Ltd.) coated with a pinylidene chloride resin was 60 μm thick as in Example 1.
And the packaging material was affixed. The oxygen permeability and the water vapor permeability of this packaging material were measured in the same manner as in Example 1. Table 1 shows the results. In addition, the bag is manufactured with the CPP side of the packaging material as the inner surface, the OPP side (outside) humidity is set to 30 ° C. and 90% atmosphere, and the oxygen permeability when the relative humidity in the bag is changed is measured. did. Table 2 shows the results.

Comparative Example 2 The moisture permeability of the present invention is 6 to 7 g /
A material having a configuration in which a barrier layer and a CPP having the same composition as in Example 1 were provided on m ² OPP was manufactured, and oxygen permeability and water vapor permeability were measured in the same manner as in Example 1. Table 1 shows the results. A bag is manufactured with the CPP side of the packaging material as the inner surface, and the humidity on the OPP side (outer side) is set to 30.
The atmosphere was set to 90 ° C. and 90%, and the oxygen permeability was measured when the relative humidity in the bag was changed. Table 2 shows the results.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

According to the present invention, the moisture permeability at a thickness of 20 μm is 5
Since a packaging material having a barrier layer is formed on one side of a plastic film of g / m ² or less by adding an inorganic layered compound, the barrier property is small even in a high-humidity atmosphere, and the range of use is limited. Can be eased. In addition, when manufacturing a packaging material, since it can be manufactured by a normal coating process, formation of a printing layer required as a packaging material,
It can be manufactured continuously at the same time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a gas barrier material of the present invention.

FIG. 2 is a sectional view showing another example of the gas barrier material of the present invention.

FIG. 3 is a sectional view showing an application example of the gas barrier material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Plastic film 2 ... Barrier layer 3 ... Printing layer 4 ... Anchor coat layer 5 ... Adhesive layer 6 ... Sealant layer

Claims (9)

[Claims] 1. A gas barrier packaging material comprising a plastic film having a thickness of 20 μm and a moisture permeability of 5 g / m ² or less provided with a barrier layer containing an inorganic layer compound and a resin on one surface. 2. The gas barrier packaging material according to claim 1, wherein a barrier layer containing an inorganic layer compound and a resin is provided on the plastic film via an anchor coat layer. 3. The method according to claim 1, wherein the barrier layer is formed by applying the barrier layer many times.
The gas barrier packaging material according to any one of the above. 4. The gas barrier packaging material according to claim 1, wherein the barrier layer contains a hydrolysis / polycondensation product of a metal alkoxide. 5. The gas barrier packaging material according to claim 1, wherein the inorganic layered compound is montmorillonite. 6. The gas barrier packaging material according to claim 1, wherein the resin is a water-soluble polymer. 7. The gas barrier packaging material according to claim 7, wherein the water-soluble polymer is polyvinyl alcohol. 8. The gas barrier packaging material according to claim 1, wherein a printing layer is formed on the barrier layer. 9. The gas barrier packaging material according to claim 1, wherein a sealant layer is formed on the barrier layer via an adhesive layer.