JPH11962A - Gas barrier film and packaging material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain thermal resistance, moisture resistance and water resistance while a gas barrier property to oxygen, steam, etc., is excellent having flexibility by a method wherein a gas barrier added layer is provided on a corona discharge treated surface of a polyolefin resin film via a primer coat layer. SOLUTION: On a PP surface to which a corona discharge treatment of a biaxially oriented coextrusion film 11 is applied, polyethylene imine is suspended in mixed solution of water and methanol, and a primer coat agent of 1% solid content is manufactured. It is set to a first unit of a multi color gravure printing machine, applied thereto so that a coated amount becomes about 0.1 g/m<2> (solid content) by a gravure coat method, and dried with hot air to prepare a primer coat layer 12. Successively, a coating agent is set to a second unit, coated so that a coated amount becomes about 0.1 to 0.5 g/m<2> (solid content) by the gravure coat method, and dried with hot air to form a gas barrier property added layer 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas barrier film of a polyolefin resin and a packaging material using the gas barrier film, and more particularly to a gas barrier film having a polyolefin resin film provided with a very thin gas barrier property imparting layer. The present invention relates to a packaging material using the gas barrier film.

[0002]

2. Description of the Related Art In recent years, packaging materials used for packaging foods and pharmaceuticals have been used to suppress deterioration of contents, particularly oxidative deterioration of proteins and oils and fats in foods, and to maintain taste and freshness. It is necessary to prevent the effects of oxygen, water vapor, and other gases that alter the contents of packaging materials in order to suppress the deterioration of the active ingredients and maintain the performance of pharmaceuticals that require sterile handling. In addition, it is required to have a gas barrier property for blocking these gases.

[0003] Therefore, polyvinyl alcohol (PV)
A), ethylene vinyl alcohol copolymer (EVO
H) or a gas barrier laminate provided by laminating or coating a polymer resin composition such as polyvinylidene chloride resin (PVDC), which is generally said to have relatively high gas barrier properties, has been generally used as a packaging film.

Further, a metal-deposited film obtained by vapor-depositing a metal or a metal compound such as aluminum (Al) on a suitable polymer resin composition (even if the resin alone does not have high gas barrier properties), , Silicon monoxide (Si
A vapor-deposited film has been developed in which a silicon oxide (SiO _x ) thin film such as O), a magnesium oxide (MgO) thin film, or the like is formed on a substrate made of a polymer material having transparency by a forming means such as vapor deposition. . These have better gas barrier properties than gas barrier materials composed of a polymer resin composition, and are less deteriorated under high humidity, so packaging films using this gas barrier material as a packaging material have begun to be generally used. I have.

[0005]

The above-mentioned PVA system and EV
The gas barrier laminate using the OH-based polymer resin composition has a large temperature dependence and a large humidity dependence, and therefore has a reduced gas barrier property under high temperature or high humidity, and particularly has a reduced water vapor barrier property. I do. In addition, depending on the use of the packaging, boiling treatment or retort treatment may significantly reduce gas barrier properties.

A gas barrier laminate using a PVDC polymer resin composition has low humidity dependency,
The oxygen barrier property is 1 cc / m ² · day · atm. There is a problem that it is difficult to realize a high gas barrier material (high gas barrier material) described below. In addition, since the coating contains a large amount of chlorine, there is a problem in terms of waste disposal such as incineration and recycling.

Further, a metal deposited film on which the above-mentioned metal or metal compound is deposited, a silicon oxide thin film such as SiO,
The vapor-deposited film on which the MgO thin film is deposited, the thin film of the inorganic compound as a gas barrier layer lacks flexibility, is weak to kneading and bending, and has poor adhesion to the base material, so care must be taken in handling, In particular, there is a problem in that cracks occur during the post-processing of the packaging material such as printing, laminating, and bag making, and the gas barrier properties are remarkably reduced.

Further, since a vacuum process such as a vacuum deposition method, a sputtering method, or a plasma enhanced chemical vapor deposition method is used for forming a thin film, an apparatus is expensive, and a high temperature is locally generated in a forming process to damage a substrate. Decomposition of additives such as low molecular weight substances or plasticizers, defects in the inorganic thin film due to degassing, pinholes, etc. may occur, and high gas barrier properties cannot be achieved,
There is a problem that the cost is high.

The vapor deposition film provided with the inorganic compound vapor deposition layer has excellent gas barrier properties and water resistance if the vapor deposition layer is thick, but it takes time to form the vapor deposition layer and the production efficiency is high. Poor, and less flexible, as described above. In particular, in the case of silicon oxide, as the thickness increases, the degree of coloring increases, and there is a problem that transparency is lacking. On the other hand, when the thickness of the vapor deposition layer is small, the degree of coloring is small and the transparency is good, but the gas barrier property and the water resistance are reduced, and a problem may occur in the content protection property.

[0010] The barrier coating agent containing water-soluble PVA as a main component can be applied directly to the surface of an oriented polypropylene film (OPP) by a gravure coating method or the like.
In some cases, the P surface was hydrophobic, so that the surface was repelled, the adhesion was not good, or the coating layer became non-uniform, resulting in a decrease in gas barrier properties.

The present invention has been made in order to solve the above-mentioned problems relating to a gas barrier film.
Based on a polyolefin-based resin film that is flexible, has excellent gas barrier properties against oxygen, water vapor, etc., has heat resistance, moisture resistance, water resistance, and has excellent suitability for contents, and can be adapted to environmental issues. It is an object of the present invention to provide a gas barrier film and a packaging material using the gas barrier film.

[0012]

Means for Solving the Problems A first invention of the present invention is:
On the corona discharge treated surface of polyolefin resin film,
A gas barrier film provided with a gas barrier property-imparting layer via a primer coat layer.

A second invention is the gas barrier film according to the first invention, wherein the polyolefin resin film is a stretched polypropylene film.

A third invention is a gas barrier film according to the first invention, wherein the polyolefin resin film is a coextruded film having a two-layer structure or a three-layer structure in which an outer layer is a stretched polypropylene film layer.

According to a fourth aspect, in the first, second and third aspects, the primer coat layer is made of a polyethyleneimine resin or a polyurethane resin, and the gas barrier property imparting layer is made of a water-soluble polymer. Is a gas barrier film composed of a layer mainly composed of a metal alkoxide and a hydrolyzate thereof.

According to a fifth aspect, in the first, second and third aspects, the primer coat layer is made of a polyethyleneimine resin or a polyurethane resin, and the gas barrier property imparting layer is made of a water-soluble polymer and tin chloride. It is a gas barrier film comprising a layer mainly composed of an aqueous solution containing at least one of them or a mixed solution of water / alcohol.

According to a sixth aspect, in the first, second and third aspects, the primer coat layer is a polyethyleneimine resin or a polyurethane resin, and the gas barrier property imparting layer is a water-soluble polymer and an inorganic layered compound. Is a gas barrier film composed of a layer mainly containing an aqueous solution containing at least one of the following, or a mixed solution of water / alcohol.

A seventh aspect of the present invention is a packaging material having a sealant layer laminated on the gas barrier property imparting layer surface of the gas barrier film.

As described above, according to the present invention, the gas barrier property-imparting layer is provided on the corona discharge treated surface of the polyolefin resin film via the primer coat layer.
Has flexibility, excellent barrier properties against oxygen, water vapor, etc., heat resistance, moisture resistance, water resistance, and
A gas barrier film based on a polyolefin-based resin film having excellent content resistance and adapted to environmental issues can be obtained.

Further, the packaging material in which a sealant layer is laminated on the gas barrier property imparting layer surface of this gas barrier film has excellent barrier properties against oxygen, water vapor, etc., and has heat resistance, moisture resistance, water resistance, and resistance to water. A packaging material based on a polyolefin-based resin film having excellent contents suitability and adapted to environmental issues can be obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. FIG. 1 is a schematic diagram illustrating the configuration of the gas barrier film of the present invention.

In FIG. 1, 11 is a polyolefin resin film, 12 is a primer coat layer, and 13 is a gas barrier property imparting layer.

Examples of the polyolefin resin film 11 include a polypropylene film and a polyethylene film. Of these, a stretched polypropylene film and a co-extruded film having a two-layer structure or a three-layer structure in which the outer layer is a stretched polypropylene are preferably used. it can. The surface of the polyolefin-based resin film 11 needs to be subjected to surface modification such as corona treatment.

The primer coat layer 12 serves to make the surface of the hydrophobic polyolefin resin film hydrophilic and to improve the adhesion between the gas barrier property-imparting layer 13 and the polyolefin resin film 11 described later. , Polyethyleneimine, organic titanium, titanium oxide,
Agents such as silane coupling agents and isocyanate compounds described below can be considered. These agents are diluted to an appropriate concentration with a solvent to form a primer coating agent, coated on a polyolefin resin film, dried by heating and formed. Since the reaction of a two-pack reaction type primer coating agent such as an isocyanate compound proceeds after being applied to a polyolefin-based resin film, it may affect the upper gas barrier property-imparting layer 13.

As a primer coating agent that sufficiently brings out the performance of the gas barrier property imparting layer, a primer coating agent using polyethyleneimine can be used optimally.

That is, the optimum primer coat layer 12
As a solid content of about 1% prepared by suspending polyethyleneimine in a solvent such as water or alcohol, or a polyurethane resin dissolved in an organic solvent such as toluene,
The primer coating agent is applied to the polyolefin-based resin film (corona discharge treated) 11 by a known coating method such as a gravure coating method in a solid content of 0.01 to 1.
It is obtained by coating so as to be about 0 g / m ² and drying with hot air or the like.

The gas barrier property-imparting layer 13 is a layer that imparts gas barrier properties to the polyolefin resin film 11.

That is, the gas barrier property-imparting layer 13 is formed of an aqueous solution containing a water-soluble polymer and at least one of (a) at least one metal alkoxide and its hydrolyzate or (b) tin chloride, or a water / alcohol mixture. It consists of a coating agent whose main component is a solution. A coating solution prepared by mixing a solution prepared by dissolving a water-soluble polymer and tin chloride in an aqueous (water or water / alcohol mixture) solvent, or a solution prepared by directly or previously hydrolyzing a metal alkoxide. The coating agent was coated on a polyolefin-based resin film 11 having been subjected to corona discharge treatment via a primer coat layer 12, dried by heating and formed. Each component contained in the coating agent will be described in detail below.

The water-soluble polymer used for the coating agent in the present invention includes polyvinyl alcohol, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, sodium alginate and the like.
In particular, when polyvinyl alcohol (PVA) is used as a coating agent for the polyolefin-based resin film of the present invention, the gas barrier properties are most excellent. The PVA referred to here is generally obtained by saponifying polyvinyl acetate. From the so-called partially saponified PVA in which acetic acid groups remain tens of percent to the completely saponified PVA in which only a few percent of acetic acid groups remain, the PVA is used. Including, but not limited to.

In addition, tin chloride is prepared from stannous chloride (SnC).
l ₂ ), stannic chloride (SnCl ₄ ), or a mixture thereof, and either an anhydride or a hydrate can be used.

Further, the metal alkoxide is represented by a general formula such as tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxy aluminum [Al (O-2′-C ₃ H ₇ ) ₃ ], M (OR) _n (M: metal such as Si, Ti, Al, Zr, R: CH ₃ ,
(An alkyl group such as C ₂ H ₅ ). Among them, tetraethoxysilane and triisopropoxyaluminum are preferable because they are relatively stable in an aqueous solvent after hydrolysis.

As the inorganic layered compound, montmorillonite, hectorite, mica and the like can be preferably used.

Each of the above-mentioned components can be added to the coating agent alone or in 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 added to a coating agent has two or more isocyanate groups (NCO groups) in its molecule. For example, tolylene diisocyanate (hereinafter referred to as TDI), triphenylmethane triisocyanate (Hereinafter, referred to as TTI), tetramethylxylene diisocyanate (hereinafter, referred to as TTI)
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, which are usually used, are used. The amount of application varies depending on the type of the coating agent, but it is desirable that the amount of application after drying be about 0.3 to 2.0 g / m ² .

It is also possible to apply the primer coating agent and the coating agent in one step using a multicolor gravure printing machine or the like. In this case, for example, the first unit may be coated with a primer coating agent, and the second unit may be coated with a coating agent (where necessary, the third unit is used as a spare unit for the coating agent).

In this manner, the gas barrier film 10 in which the gas barrier property-imparting layer 13 is provided on the PP surface of the polyolefin resin film 11 via the primer coat layer 12 can be produced. The gas barrier property-imparting layer surface of the gas barrier film 10 and a heat-fusible plastic film such as an unstretched polypropylene film (CPP) are dry-laminated as the sealant layer 14 using, for example, a polyurethane-based adhesive, and the packaging material 1 (See FIG. 1).

[0038]

EXAMPLES Examples of the present invention will be described below more specifically. Example 1 First, a polyolefin resin film 11 was used.
Was prepared as follows. That is, a polypropylene resin (PP) and a polyethylene resin (PE) are supplied to separate extruders, melt-extruded, merged in a die, extruded from a slit, wound around a cooling roll, cooled and solidified on a roll, and PP18 μm, PE 2 μm, A biaxially stretched coextruded film 11 having a total thickness of 20 μm was obtained.

The PP surface of the biaxially stretched coextruded film was subjected to corona discharge treatment to have a surface wetting index of 38 to 42 dyn.
e / cm (based on JIS K6768).

Next, on the PP surface of the biaxially stretched coextruded film subjected to the corona discharge treatment, a primer coating agent having a solid content of 1% prepared by suspending polyethyleneimine in a mixed solution of water and methanol was used. It was set in the first unit of a color gravure printing machine, applied by a gravure coating method so that the coating amount was about 0.1 g / m ² (solid content), and dried with hot air to obtain a primer coat layer 12.

Subsequently, the second unit was prepared according to the following recipe.
Set the coating agent on the primer coat layer
The coating amount is 0.1 to 0.5 g by gravure coating method
/ M ^Two(Solid content) and dry with hot air
As a result, the gas barrier property imparting layer 13 was formed. In addition,
In order to avoid poor drying, use a coating agent with the second unit.
It may be applied separately to two units of the third unit
No.

10. Formulation of Coating Agent Tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ]
To 4 parts, 89.6 parts of hydrochloric acid (0.1N) was added, and the mixture was stirred for 30 minutes and hydrolyzed, and 6 parts of a hydrolysis solution having a solid content of 3% by weight (in terms of SiO ₂ ) and 3.0% by weight of PVA water / A composition obtained by mixing 4 parts of an isopropyl alcohol (90/10) solution.

As described above, the gas barrier property imparting layer 1 is provided on the PP surface of the biaxially stretched co-extruded film 11 which is a polyolefin resin film via the primer coat layer 12.
The gas barrier film 10 provided with No. 3 was produced.

Finally, the gas-barrier property-imparting layer surface of the gas-barrier film 10 and the CPP 14 having a thickness of 30 μm were dry-laminated using a polyurethane adhesive to produce a packaging material 1 (see FIG. 2).

Comparative Example 1 Biaxially stretched coextruded film 1
In place of the gas barrier film 10 having a thickness of 20 μm in which a gas barrier property-imparting layer 13 is provided on the PP surface via a primer coat layer 12, a commercially available 20 μm-thick modified biaxially stretched polypropylene film (OPP) is used. Then, the modified surface of the modified OPP and a CPP having a thickness of 30 μm as a sealant layer were dry-laminated using a polyurethane-based adhesive in the same manner as in Example 1, and the modified OPP (20 μm thickness) / D
A packaging material having an L / CPP (thickness of 30 mμ) was prepared.
However, DL means that the adhesive is applied by a dry lamination method using a polyurethane adhesive. In addition, modified O
A polyethyleneimine-based primer coating agent is applied to the modified surface of PP.

The oxygen gas permeability of the two kinds of packaging materials thus obtained and the adhesive strength at the interface between the polyolefin resin film and the sealant layer were measured by the following methods. Table 1 shows the results. Oxygen gas permeability @ MOCON OXTRAN 10 /
50 ° C., 70% RH. Using an oxygen gas permeability measuring device (manufactured by Modern Control). Measured under atmosphere. Adhesive strength between polyolefin resin film and sealant layer ラ ン ト Tensilon RTM250
Mold release (crosshead speed 300 mm / min.
Measured with a sample width of 15 mm).

[0047]

[Table 1]

Considering from Table 1, the gas barrier film and the packaging material of the present invention show good results in both oxygen gas permeability and adhesive strength (Example 1). This is high because the water-soluble polymer and the metal alkoxide and its hydrolyzate as a main component are provided on the polyolefin-based resin film via the polyethyleneimine-based primer coat layer to provide a gas barrier property-imparting layer. This indicates that the adhesion to the sealant layer could be improved while maintaining the gas barrier properties. The adhesive strength with the sealant layer is 100 gf if the contents are limited to dried products such as confectionery.
It can be used if it is more than / 15 mm wide, but at least 200 gf /
A width of about 15 mm is required.

Example 2 An OPP (20 μm thick) / primer was prepared in the same manner using the same primer coating agent and coating agent as in Example 1 except that the polyolefin-based resin film was changed to a single 20 μm thick OPP. A gas barrier film having a constitution of a coat layer / gas barrier property imparting layer was produced, and further, OPP (20 μm thick) / primer coat layer / gas barrier property imparting layer / DL / CPP
A packaging material having a (30 μm thickness) configuration was produced (detailed production method is omitted).

Example 3 A high-moisture-proof OPP (25 μm) was prepared in the same manner as in Example 1 except that the polyolefin-based resin film was made of a single high-humidity-proof OPP having a thickness of 25 μm. Thickness) / primer coat layer / gas barrier property imparting layer to produce a gas barrier film, and furthermore, a high moisture-proof OPP
A packaging material having a structure of (25 μm thickness) / primer coat layer / gas barrier property imparting layer / DL / CPP (30 μm thickness) was produced (detailed production method is omitted).

Comparative Example 2 A K-coated OPP (20 μm thick) was produced in the same manner as in Comparative Example 1 except that the gas barrier film was a commercially available K-coated OPP having a thickness of 20 μm (EG10 manufactured by Daicel Chemical Industries, Ltd.). / DL / CP
A packaging material having a P (30 μm thickness) configuration was manufactured (detailed manufacturing method is omitted).

The oxygen gas permeability and the water vapor permeability of the three kinds of packaging materials thus obtained were measured by the methods described below. Table 2 shows the results. Oxygen gas permeability @ MOCON OXTRAN 10 /
50 ° C., 70% RH. Using an oxygen gas permeability measuring device (manufactured by Modern Control). Measured under atmosphere. Water vapor permeability @PARMATRAN W600 Using a water vapor permeability measuring device (manufactured by Modern Control Co.), 40 ° C, 90% RH. Measured under atmosphere.

[0053]

[Table 2]

As can be seen from Table 2, the gas barrier film and the packaging material of the present invention show good results in both oxygen gas permeability and water vapor permeability (Examples 2 and 3).
This is high because the water-soluble polymer and the metal alkoxide and its hydrolyzate as a main component are provided on the polyolefin-based resin film via the polyethyleneimine-based primer coat layer to provide a gas barrier property-imparting layer. This shows that a gas barrier film having both gas barrier properties and high water vapor barrier properties can be obtained.

[0055]

Conventionally, only the commercially available modified OPP could be used. However, a polyethyleneimine-based primer coating agent was applied to a polyolefin-based resin film, and a water-soluble polymer and A layer containing the above metal alkoxide and its hydrolyzate as a main component, or
By providing a layer containing a water-soluble polymer and an aqueous solution containing at least one of tin chloride or a water / alcohol mixed solution as a main component, excellent gas barrier properties, heat resistance, moisture resistance,
A polyolefin-based gas barrier film and a packaging material using the gas barrier film, which have water resistance, are excellent in content resistance, and can be adapted to environmental issues, can be manufactured using general equipment. It is now possible.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view illustrating an example of a layer configuration of a gas barrier film of the present invention.

FIG. 2 is an explanatory cross-sectional view showing an example of a packaging material obtained by laminating a sealant layer on the gas barrier property imparting layer surface of the gas barrier film of the present invention.

[Explanation of symbols]

 1 packaging material 10 gas barrier film 11 polyolefin resin film 12 primer coat layer 13 gas barrier imparting layer 14 sealant layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B65D 65/40 B65D 65/40 A // B29K 23:00 75:00 79:00 B29L 7:00 9:00

Claims (7)

[Claims] 1. A gas barrier film characterized in that a gas barrier property-imparting layer is provided on a corona discharge treated surface of a polyolefin resin film via a primer coat layer. 2. The polyolefin resin film is a stretched polypropylene film.
The gas barrier film according to the above. 3. A polyolefin resin film having a two-layer structure in which an outer layer is a stretched polypropylene film layer or a three-layer structure.
The gas barrier film according to claim 1, which is a co-extruded film having a layer structure. 4. The primer coat layer is a polyethyleneimine-based resin or a polyurethane-based resin, and the gas-barrier property-imparting layer is a layer mainly composed of a water-soluble polymer, at least one metal alkoxide and a hydrolyzate thereof. The gas barrier film according to claim 1, 2 or 3, wherein 5. The primer coat layer is a polyethyleneimine resin or a polyurethane resin, and the gas barrier property-imparting layer is mainly composed of an aqueous solution containing a water-soluble polymer and at least one of tin chloride, or a mixed solution of water / alcohol. The gas barrier film according to claim 1, 2 or 3, comprising a layer. 6. The primer coat layer is a polyethyleneimine-based resin or a polyurethane-based resin, and the gas-barrier property-imparting layer is an aqueous solution containing at least one of a water-soluble polymer and an inorganic layered compound, or a water / alcohol mixed solution as a main component. 4. The gas barrier film according to claim 1, wherein the gas barrier film comprises a layer. 7. A packaging material comprising the gas barrier film according to claim 1, 2, 3, 4, 5 or 6, and a sealant layer laminated on the gas barrier property imparting layer surface.