JP3240902B2 - Packaging materials and packaging bags with excellent gas 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 packaging material having a light-shielding metal vapor-deposited layer provided with a small reduction in gas barrier property due to heat sealing, and a packaging bag using the packaging material. .

[0002]

2. Description of the Related Art Conventionally, packaging bags for confectionery and the like, particularly packaging bags used for snack confectionery containing oil, are required to have a gas barrier property for blocking gases such as oxygen and water vapor, as well as sunlight and fluorescent light. There is a demand for a light-blocking property for blocking light such as lamp light. This prevents the confectionery, etc., which is the content, from being moistened by water vapor, and prevents the fats and oils in the content from being oxidized and degraded due to the influence of oxygen, particularly oxygen and light rays, thereby preventing taste and the like from being impaired. To do that.

[0003] For this purpose, conventionally, this kind of packaging bag material; that is, as a packaging material, a plastic film is mainly used, and a metal foil or a metal vapor-deposited layer for providing light shielding and gas barrier properties is used. The provided one is used. In particular, in recent years, those provided with a metal deposition layer using a small amount of metal are widely used. As the above metal, it is common to use aluminum, which is inexpensive and easy to handle.

[0004]

The above-mentioned metal-deposited layer is a very thin layer having a light-shielding property, for example, about 500 to 800 ° in the case of aluminum deposition. (25 μm) /
Printing layer / Ethylene-methacrylic acid copolymer film (EMA
A) (15 μm) / aluminum vapor-deposited layer (500 °) -unstretched polypropylene film (25 μm). When a simple packaging material is used, this packaging material is heat-sealed into a bag such as a pillow packaging bag. Due to heat and pressure, a fine crack (crack) was sometimes generated in the heat-sealed portion and the metal deposition layer near the edge thereof. When this crack occurs, the originally intended gas barrier property is impaired, and the contents cannot be sufficiently protected in some cases.

In order to prevent the occurrence of such cracks, the following structure in which a vapor deposited film is sandwiched between a printing substrate and a sealant film has been used.
The number of layers increases, which is disadvantageous in terms of cost. Outside: biaxially oriented polypropylene film (20 μm) /
Printing layer / sand laminated polyethylene (15μm) /
Aluminum deposited layer (500Å)-biaxially oriented polyethylene terephthalate film (12 µm) / sand laminated polyethylene (15 µm) / unstretched polypropylene film (20 µm)

Accordingly, the present invention provides a packaging material which has a reduced number of layers, has a cost advantage, and has a metal vapor-deposited layer having a light-shielding property, while reducing or preventing the occurrence of cracks at the time of heat sealing. This is to provide a packaging bag used.

[0007]

That is, the present invention relates to a heat-adhesive resin film provided with a metal deposition layer, a water-soluble polymer and a coating agent containing a metal alkoxide or a hydrolyzate thereof, or a water-soluble polymer. A gas barrier formed by laminating a substrate film provided with a coating layer formed by applying and forming a coating agent containing tin chloride with a metal deposition layer surface and a coating layer surface facing each other, and laminating with an adhesive layer interposed therebetween. It is an excellent packaging material.

In the above packaging material, a printing layer can be provided between the coating layer and the base film or on the coating layer provided on the base film. The heat-adhesive resin film, being a non-stretched polypropylene film, has excellent heat resistance as a deposition substrate,
preferable. Further, the adhesive layer can be a known adhesive or a heat-adhesive resin. The above packaging materials are
A packaging bag can be obtained by making a bag by heat sealing with the heat-adhesive resin film on the inner surface side.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the packaging material of the present invention.

As shown in FIG. 1, the packaging material of the present invention comprises:
A heat-adhesive resin film 11 provided with a metal-deposited layer 12 (hereinafter, this film is referred to as a vapor-deposited sealant 1), and a base film 21 provided with a later-described coating layer 22 (hereinafter, referred to as an outer-layer film 2). Are laminated with the metal deposition layer 12 and the coating layer 22 facing each other as shown in the figure, and laminated with the adhesive layer 3 interposed therebetween. In addition, the outer layer film 2 has a coating layer 2
2 includes a print layer 23 provided thereon.

First, the heat-adhesive resin film 11 of the vapor-deposited sealant 1 functions as a sealant (heat seal layer) when the packaging material obtained by the present invention is formed into a packaging bag by heat sealing. At the same time, the heat-adhesive resin film 11 also functions as a deposition base for the metal deposition layer 12. Therefore, this film needs to be made of a heat-sealable material having a certain degree of heat resistance. Therefore, as this film, a non-stretched polypropylene film is preferable. The thickness of this film is generally about 12 to 100 μm.

Next, the metal deposition layer 12 formed on the heat-adhesive resin film 11 imparts a gas barrier property and a light shielding property to the obtained packaging material. Aluminum is preferred as the metal in terms of cost and ease of handling.

The light shielding property of the packaging material is preferably such that the total transmittance in the visible light region is 0.6% or less, and the gas barrier property depends on the contents. Oxygen permeability is 5cc / m ² · da in the packaging material
y or less (MOCON method, 30 ° C. × 70% RH), water vapor permeability of 1 g / m ² · day or less (MOCON method, 40 ° C.
× 90% RH). In order to realize such a light shielding property and a gas barrier property, the thickness of the metal deposition layer 12 is 500 to 800 in the case of aluminum.
Å is preferred. In addition, this metal deposition layer 12
Can be formed by a well-known forming means; that is, a vacuum deposition method, an ion plating method, a sputtering method, or the like.

The base film 21 of the outer layer film 2 is a layer which is a main component of the packaging material, and is preferably a material having excellent mechanical strength and printability. Specifically, it is in the form of a sheet or a film, and is composed of polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate,
Polyethylene naphthalate and the like), polyamides (nylon-6, nylon-66 and the like), polyvinyl chloride, polyimide, and the like, or copolymers of these polymers, which are usually used as packaging materials, can be used. Among them, biaxially oriented polyethylene terephthalate film, biaxially oriented polypropylene film, biaxially oriented nylon film,
A film having a thickness of about 12 to 100 μm is preferably used. In particular, it is preferable to use a biaxially stretched polypropylene film for the purpose of highly preventing water vapor transmission.

Further, for the purpose of decoration or the like, a paper layer or the like can be used by being added to the base film 21 entirely or partially. Known additives such as, for example, an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, and a coloring agent can be added to the base film 21, and are appropriately added as necessary. Further, the surface of the base film 21 may be subjected to a surface modification such as a corona treatment and an anchor coat treatment to improve the adhesion of a layer formed thereon.

The coating layer 22 provided on the base film 21 is formed of an aqueous solution or water containing a water-soluble polymer and at least one of (a) one or more metal alkoxides and a hydrolyzate thereof and (b) tin chloride. / Alcohol mixed solution.
That is, a coating agent obtained by dissolving a water-soluble polymer and a metal alkoxide (or a hydrolyzate thereof) or / and tin chloride in an aqueous (water or water / alcohol mixture) solvent is coated on the base film 21. ,
The outer layer film 2 can be obtained by forming the coating layer 22 by heating and drying.

The outer layer film 2 is provided between the base film 21 and the coating layer 22 or on the coating layer 22 formed on the base film 21.
A normal print layer 23 can be formed. In the illustrated embodiment, the print layer 23 is provided on the entire surface of the coating layer 22. However, the present invention is not limited to this, and it is possible to provide the print layer 23 partially.

Next, 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, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when polyvinyl alcohol (PVA) is used as a coating agent for the gas barrier packaging material of the present invention, the gas barrier properties are most excellent. PVA here
Is generally obtained by saponifying polyvinyl acetate, and includes so-called partially saponified PVA in which acetic acid groups remain tens of percent, to fully saponified PVA in which only a few percent of acetic acid groups remain, and is particularly limited. It is not something to be done.

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, Ai, 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.

The above-mentioned components can be added to the coating agent alone or in combination of several components. Further, as long as the barrier property of the coating agent is not impaired, an isocyanate compound, a silane coupling agent, a dispersant, a stabilizer or a stabilizer is used. 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 TDI)
TTI), tetramethylxylene diisocyanate (hereinafter, referred to as 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 thickness of the coating depends on the type of the coating agent, in solid content 0.1 to 3.0 g / m ^2, preferably it is desirable that the 0.1 to 1.0 g / m ^2.

With respect to the coating layer 22 described above,
Although details are often unknown, the composition of the coating agent is composed of an inorganic component composed of a metal alkoxide or / and tin chloride, and a water-soluble polymer. It is a highly reactive inorganic component that forms a chain or three-dimensional polymer through a polycondensation reaction and undergoes further polymerization by evaporation of the solvent accompanying heating and drying. It is considered to form a complex. For this reason, the coating layer 22 shows a high gas barrier property,
In addition, it is very flexible.

The packaging material of the present invention can be obtained by laminating the vapor deposited sealant 1 and outer layer film 2 obtained as described above with the adhesive layer 3 interposed therebetween. One of the laminating methods is a laminating method using an adhesive such as a well-known dry laminating method or a non-solvent laminating method, and the adhesive layer 3 is a layer of the adhesive.

Another laminating method is to apply a heat-adhesive resin such as low-density polyethylene, ethylene-vinyl acetate copolymer, or ionomer to a vapor-deposited sealant 1 and an outer film 2.
This is a so-called sand lamination method in which the film is melted and extruded into a film between the layers and laminated by the adhesive force. The adhesive layer 3 in this method is a layer of the extruded thermo-adhesive resin.

The packaging material of the present invention obtained as described above is formed into a well-known three-sided seal bag, four-sided seal bag, gusset-shaped bag, standing pouch, pillow packaging bag, etc., with the vapor-deposited sealant 1 as the inner surface. It is used by making a bag by heat sealing. At this time, the heat and pressure of the heat seal are applied to the heat seal portion or the vicinity of the edge thereof. However, since the coating layer 22 is relatively flexible, the occurrence of cracks in the metal deposition layer 12 is reduced or prevented. Further, since the coating layer 22 is a layer having an excellent barrier property, even if a crack occurs in the metal deposition layer 12, the coating layer 22 compensates for a decrease in the gas barrier property of the corresponding portion, so that the gas barrier property of the entire packaging material is reduced. Is very small.

[0027]

【Example】

<Example 1> A biaxially stretched polypropylene film having a thickness of 30 µm was used as a base film, and a coating solution having the following composition was applied to one surface of the base film by a gravure coater and dried to form a coating layer. Thus, an outer layer film was formed. The coating amount (solid content) of the coating layer is 0.3 g
/ M ² .

9. Components of coating liquid Tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ]
89.6 g of hydrochloric acid (0.1 N) was added to 4 g, and the mixture was stirred for 30 minutes and hydrolyzed to obtain a hydrolysis solution (A) having a solid content of 3 wt% (in terms of SiO ₂ ), and a polyvinyl alcohol of 3.0%.
A composition obtained by mixing a wt% water / isopropyl alcohol (90/10) solution (B).

When the oxygen permeability and the water vapor permeability of the obtained outer layer film were measured, the oxygen permeability was 6 to 23.
cc / m ² · day, water vapor permeability is about 4.0 g / m ² · da
y.

Apart from this, a commercially available unstretched polypropylene film (thickness: 40 μm, trade name: VM-CPP) provided with a vapor-deposited aluminum layer (thickness: about 500 °)
2403, manufactured by Toyo Metallizing Co., Ltd.) was prepared as a vapor deposition sealant. When the oxygen permeability and water vapor permeability of this film were measured, the oxygen permeability was about 2
5 cc / m ² · day, water vapor permeability is about 1.0 g / m ² ·
day.

Next, the outer layer film and the vapor-deposited sealant are combined with a urethane-based dry laminating adhesive (trade name: Takelac A515 / A50, manufactured by Takeda Pharmaceutical Co., Ltd.)
Was provided on the coating layer side of the outer layer film at an application amount of about 2.5 g / m ² , and laminated by a dry lamination method to obtain a packaging material of the present invention shown in FIG. 1 (but without a printed layer). Was. When the oxygen permeability and the water vapor permeability of this packaging material were measured, the oxygen permeability was about 3.0 cc /
m ² · day, and the water vapor permeability was about 0.4 g / m ² · day.

Next, after the packaging material was formed into a pillow packaging bag by heat sealing, a portion near the edge of the heat sealing portion was sampled to measure oxygen permeability and water vapor permeability. Once again 3~5cc / m ²
-Day, the water vapor permeability was about 0.3 g / m ² · day.

Comparative Example 1 For comparison, a packaging material without the coating layer of the present invention was prepared as follows. The same biaxially stretched polypropylene film (30 μm) used in Example 1 and a 25 μm-thick unstretched polypropylene film (evaporated sealant, trade name: V provided with a 500-mm-thick aluminum evaporation layer)
M-CPP2403, manufactured by Toyo Metallizing Co., Ltd.)
Was prepared. Next, an ethylene-methacrylic acid copolymer (EMAA) resin is melted, extruded between the two films into a film having a thickness of 15 μm, and the two films are laminated by a sand lamination method. Comparative Example 1)
I got Structure: OPP / S-EMAA / VM-CPP Here, OPP: biaxially stretched polypropylene film S-EMAA: ethylene-methacrylic acid copolymer by sand lamination method VM-CPP: non-stretched polypropylene film with aluminum vapor deposited layer

When the oxygen permeability and the water vapor permeability of this packaging material were measured, the oxygen permeability was about 18 cc / m ² ···
Day, the water vapor transmission rate was about 0.25 g / m ² · day.

Next, this packaging material was formed into a pillow packaging bag in the same manner as in Example 1, and a portion near the edge of the heat seal portion was sampled to measure oxygen permeability and water vapor permeability. Oxygen permeability is 200cc / m ² · da
Above y, the water vapor transmission rate was about 1.1 g / m ² · day.

<Comparative Example 2> A packaging material in which a film provided with a metal deposition layer was protected by being sandwiched between two films was prepared as follows. As the film on the outer surface side, the same biaxially stretched polypropylene film (30 μm) used in Example 1 and a non-stretched polypropylene film having a thickness of 18 μm as a sealant (trade name:
Taiko FNC, manufactured by Nimura Chemical Co., Ltd.) and thickness 5
Thickness 12 provided with an aluminum evaporation layer of 00 °
A μm biaxially stretched polyethylene terephthalate film (evaporated film, trade name: MLPET-E, manufactured by Tokyo Cellophane Paper Co., Ltd.) was prepared. These films
Each of the low-density polyethylene resins is melted, extruded between the above films into a film having a thickness of 13 μm, and laminated by a sand lamination method.
I got Configuration: OPP / S-PE / VM-PET / S-PE / C
PP Here, OPP: Biaxially stretched polypropylene film S-PE: Low density polyethylene by sand lamination method VM-PET: Biaxially stretched polyethylene terephthalate film with aluminum deposited layer CPP: Unstretched polypropylene film

When the oxygen permeability and the water vapor permeability of this packaging material were measured, the oxygen permeability was about 0.7 cc / m ^2.
-Day, the water vapor permeability was about 0.3 g / m ² · day.

Next, this packaging material was formed into a pillow packaging bag in the same manner as in Example 1, and a portion near the edge of the heat-sealed portion was sampled to measure oxygen permeability and water vapor permeability. Oxygen permeability is 1-9cc / m ² · da
y (variation was large depending on the measurement location), and the water vapor permeability was about 0.6 g / m ² · day.

As is clear from the above results, the packaging material of the present invention (Example 1) was a packaging material having excellent gas barrier properties (low oxygen permeability). It is considered that a high barrier value is obtained by compensating for defects, pinholes, and the like by combining gas-barrier packaging materials. Further, it can be seen that the packaging material of the present invention has a small reduction in gas barrier properties even by heat sealing, and has excellent gas barrier properties despite its simple configuration.

On the other hand, in the packaging material of Comparative Example 1 provided with no coating layer, cracks occurred in the aluminum vapor-deposited layer due to heat sealing, and gas barrier properties were obtained.
In particular, the oxygen barrier property was significantly reduced.

The packaging material of Comparative Example 2 in which the aluminum vapor-deposited film is sandwiched between two films has a smaller reduction in gas barrier properties than Comparative Example 1, but has a smaller film thickness than the present invention. Despite having a large number of five-layer structures, the gas barrier properties were lower than those of the packaging material of the present invention.

[0042]

Since the packaging material of the present invention has the above-described structure, the gas barrier properties of the metal-deposited layer and the coating layer act synergistically to provide a high gas content despite the simple structure. It has barrier properties and is also excellent in cost. Further, since the packaging material of the present invention has a configuration in which a flexible coating layer is provided, the occurrence of cracks in the metal deposition layer due to heat sealing is reduced or prevented. Barrier properties are maintained. Also, during processing such as bending at the time of bag making, a decrease in gas barrier properties is similarly prevented. Therefore, the packaging bag made of the packaging material of the present invention has a high effect of preventing the permeation of oxygen and water vapor. There is no fear of damage. Furthermore, since the coating layer for realizing the gas barrier property of the present invention is formed by applying a coating agent and drying by heating, the thickness of the coating layer is easily adjusted, and therefore the gas barrier property of the packaging material is improved. Is easy to control.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... vapor deposition sealant 2 ... outer layer film 3 ... adhesive layer 11 ... thermoadhesive resin film 12 ... metal vapor deposition layer 21 ... base film 22 ... coating layer 23 ... printing layer

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C08J 7/04 C08J 7/04 P 7/06 7/06 Z (56) References JP-A-8-318591 (JP, A) JP-A-7-164591 (JP, A) JP-A-6-316025 (JP, A) JP-A-7-207431 (JP, A) JP-A-1-30748 (JP, A) JP-A-6-116542 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 15/08

Claims (7)

(57) [Claims] 1. A heat-adhesive resin film provided with a metal-deposited layer, and a base film provided with a coating layer formed by applying a coating agent containing a water-soluble polymer and a metal alkoxide or a hydrolyzate thereof. A packaging material having excellent gas barrier properties, which is obtained by laminating a metal vapor-deposited layer surface and a coating layer surface so as to face each other and laminating with an adhesive layer interposed therebetween. 2. A heat-adhesive resin film provided with a metal vapor-deposited layer, and a base film provided with a coating layer formed by applying a coating agent containing a water-soluble polymer and tin chloride, and A packaging material with excellent gas barrier properties, which is obtained by laminating coating layers facing each other and laminating with an adhesive layer in between. 3. The printing method according to claim 1, wherein a printing layer is provided between the coating layer and the base film or on the coating layer provided on the base film. Crab packaging material. 4. The packaging material according to claim 1, wherein the heat-adhesive resin film is a non-oriented polypropylene film. 5. The packaging material according to claim 1, wherein the adhesive layer comprises an adhesive. 6. The packaging material according to claim 1, wherein the adhesive layer is made of a thermo-adhesive resin. 7. A packaging bag produced by heat-sealing the packaging material according to claim 1 with the heat-adhesive resin film on the inner surface side.