JP3228363B2 - Paper carton and packaging material for paper carton - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention has excellent gas barrier properties,
Drinks such as milk, juice, carbonated beverages, alcohols such as sake, shochu, whiskey, seasonings such as soy sauce and sauce;
Paper suitable for storage of cooking sources, soups, etc.
The present invention relates to a packaging material for carton and paper carton.

[0002]

2. Description of the Related Art Paper cartons having excellent gas barrier properties and packaging materials for paper cartons are obtained by laminating aluminum foil with paper or the like to obtain PE (polyethylene) / paper /
Known are those in the form of aluminum foil / PE, those in which Al foil is replaced with an aluminum vapor-deposited film, vinylidene chloride or ethylene vinyl alcohol copolymer, and those using a thin film such as silicon oxide.

[0003]

The conventional paper described above
Carton and paper carton packaging materials have the following problems. Those using aluminum foil and aluminum vapor deposition have excellent gas barrier properties, but are opaque and have the drawback that the contents during packaging cannot be seen. In addition, since microwaves do not transmit, heating with a microwave oven is impossible, and aluminum is further coated with paper.
If it is included in a part of the packaging material for carton and paper carton, there is a problem that the plastic film or paper cannot be collected and reused. Vinylidene chloride or ethylene vinyl alcohol copolymer is
Some of the components of the carton have insufficient gas barrier properties against water vapor, oxygen, etc., and have a short shelf life for the contents. In addition, vinylidene chloride-based compounds are easily thermally decomposed and difficult to be recycled, and there is a concern about the influence on the global environment such as generation of chlorine gas during incineration. Also,
Although ethylene vinyl alcohol has excellent barrier properties during drying, the oxygen barrier properties are significantly reduced under high humidity, and the storage period is shortened.

Japanese Patent Publication No. 51-48511 discloses a synthetic resin.
Si on body surface_xO_y(Eg SiO _TwoGas deposited)
Although barrier films have been proposed,
Good SiO_xThe system (x = 1.3-1.8) has a brown color
And its coating is brittle, and it
Paper carton and paper carton packaging
If materials are handled severely, the gas barrier
There is a drawback that it decreases. Steam aluminum oxide
(Japanese Patent Application Laid-Open No. 62-101428)
There are some that can be seen, but the initial oxygen barrier
Not expensive. Deterioration of oxygen barrier properties when bent further
Large, paper carton and packaging for paper carton
Oxidation of contents when part or all of material composition
Is not enough to protect against
Severe handling with both elemental barrier properties and water vapor barrier properties
Can't withstand.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to a paper paper comprising a gas barrier film having a part or the whole of a gas barrier film which is excellent in gas barrier properties, has high bending resistance and is economically advantageous. -Ton and paper carton packaging materials. That is, according to the present invention, a thin film having a composition mainly composed of aluminum oxide and silicon oxide is provided on at least one surface of the plastic base material.
A paper carton and a packaging material for paper carton, wherein the gas barrier film is contained in an amount of 9% by weight or a part thereof, preferably a specific gravity of the thin film. Are paper cartons and packaging materials for paper cartons, wherein the gas barrier film satisfies the following formula: D = 0.01A + b (where D: specific gravity of the thin film, A: weight% of aluminum oxide in the thin film, 1.6 ≦ b ≦ 2.
2)

The plastic substrate referred to in the present invention is a film obtained by melt-extruding an organic polymer and stretching, cooling, and heat setting in the longitudinal direction and / or the width direction as necessary. Organic polymers include polyethylene, polypropylene, polyethylene terephthalate, polyethylene-2,6-naphthalate, nylon 6, nylon 4,
Nylon 66, nylon 12, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamide imide, polyimide, polyether imide, polysulfone, polyphenylene sulfide, polyphenylene oxide and the like. These (organic polymer) organic polymers may be copolymerized or blended in small amounts with other organic polymers.

Further, known additives such as an ultraviolet absorber, an antistatic agent, a plasticizer, a lubricant,
A coloring agent or the like may be added, and the transparency is not particularly limited. However, when used as a transparent gas barrier film, a film having a transmittance of 50% or more is preferable. The plastic film of the present invention may be subjected to corona discharge treatment, glow discharge treatment, or other surface roughening treatment prior to laminating the thin film layer, as long as the object of the present invention is not impaired. Also, a known anchor coat treatment, printing, and decoration may be applied. The thickness of the plastic film of the present invention is preferably in the range of 5 to 500 μm, more preferably 8 to 300 μm.

It is considered that the aluminum oxide / silicon oxide thin film is composed of a mixture or a compound of aluminum oxide and silicon oxide. The aluminum oxide here is composed of a mixture of various aluminum oxides such as Al, AlO, and Al ₂ O ₃ , and the content of each of the aluminum oxides in the aluminum oxide differs depending on the production conditions. Silicon oxide is considered to be composed of Si, SiO, SiO _{2 and the} like, and their ratios also differ depending on the preparation conditions. In the present invention, the ratio of aluminum oxide in the thin film is 20% by weight or more and 99% by weight or less, preferably 30% by weight or more and 95% by weight or less. Also, this component may contain a trace amount (up to 3% of all components) of other components as long as the characteristics are not impaired. The thickness of the thin film is not particularly limited, but is preferably from 50 to 8000 A, more preferably from 70 to 5000 A, from the viewpoint of gas barrier properties and flexibility.

In order to prepare such an aluminum oxide / silicon oxide based thin film, a PVD method (physical vapor deposition method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or the like, or
A CVD method (a chemical vapor deposition method) or the like is appropriately used. For example, in a vacuum deposition method, Al ₂ O is used as a deposition source material.
₃ and SiO ₂ or a mixture of Al and SiO ₂ is used,
The heating method includes resistance heating, high-frequency induction heating,
Electron beam heating or the like can be used. Further, oxygen, nitrogen, water vapor, or the like may be introduced as a reactive gas, or reactive vapor deposition using means such as ozone addition or ion assist may be used. Further, the production conditions may be changed as long as the object of the present invention is not impaired, such as applying a bias to the substrate, increasing the substrate temperature, or cooling.
The same applies to other production methods such as a sputtering method and a CVD method. The product of the present invention may be used as it is, or may be used by laminating or coating another organic polymer film or a thin layer.

The specific gravity referred to in the present invention refers to the ratio of the mass of a substance occupying a certain volume at a certain temperature to the mass of a standard substance having the same volume (water at 4 ° C.). The measurement of specific gravity is
Normally, the mass and volume of the object may be measured, and the ratio of the mass to the same volume of water at 4 ° C. may be obtained. However, it is difficult to measure the volume in the measurement of the thin film of the present invention. Then, first, the thin film is peeled off from the substrate or only the substrate is dissolved to form a single film consisting of only the thin film.
It is desirable to use a specific gravity measurement method as described in 7112). For example, in the flotation method, a sample is immersed in a solution having a known specific gravity, and the specific gravity of the thin film can be measured from the flotation state. As this solution, a mixed solution of carbon tetrachloride and bromoform, methylene iodide, or the like can be used. The specific gravity value can also be measured by a density gradient tube method in which a single film is immersed in a solution having a continuous density gradient.

The relationship between the specific gravity of the thin film thus obtained and the weight percentage of aluminum oxide in the thin film is expressed by D
= 0.01A + b (D: specific gravity of the thin film, A: weight% of aluminum oxide in the thin film), when the value of b is less than 1.6, the structure of the aluminum oxide / silicon oxide thin film Becomes coarse and sufficient gas barrier properties cannot be obtained. Further, the value of the specific gravity of the thin film is a b value,
In the case of a region larger than 2.2, the initial gas barrier properties after film formation are excellent, but the film is too hard, the mechanical properties, particularly the gelbo properties, are inferior, and the gas barrier properties after treatment are greatly reduced. Not suitable for use as a conductive film. For the above reasons, the specific gravity of the aluminum oxide / silicon oxide thin film preferable as the paper carton and the packaging material for the paper carton is determined by the relationship between the specific gravity of the thin film and the aluminum oxide composition ratio in the thin film. D = 0.01A +
When expressed by a relational expression of b (D: specific gravity of the thin film, A: weight% of aluminum oxide in the thin film), the value of b is 1.6 to 2.2, more preferably 1.7 to 2.1. It is. (Fig. 1)

In the present invention, paper carton refers to a composite paper container, and as a packaging material for paper carton, paper, a plastic film or the like and a gas barrier film are used. Use a laminated product. The shape and type are not particularly limited, such as a roof shape (gebel top), a brick shape (brick shape), a rectangular parallelepiped, and a cup shape. Moreover, you may combine with an inner bag, a spout, etc. The paper in the present invention
The contents to which the carton can be applied include milk, yogurt,
It is a drink such as gold juice and carbonated drink, alcohols such as sake, shochu, whiskey and the like, and seasonings such as soy sauce and sauce, etc., but not particularly limited thereto.

Next, the present invention will be described with reference to examples.

Embodiment 1 As an evaporation source, a size of about 3 to 5 mm was used.
Flaky Al_TwoO_Three(Purity 99.5%) and SiO_Two
(Purity: 99.9%), using electron beam evaporation method
μm thick PET film (Toyobo Co., Ltd .: E510
0) An aluminum oxide / silicon oxide based thin film is formed on
Was. The deposition conditions include the electron gun (EB gun)
The composition current was 1.2 A, the heating ratio was 30:10, and the composition was
The ratio is Al_Two O_Three : SiO _Two = 60: 40
Was. The thickness of the deposited film is 600A (angstrom)
And PE (polyester) 40μm, laminated with paper
Thus, Examples 1 to were produced. This packaging film
Was measured. As a comparative example, 1-PE
T, -K-PET (vinylidene chloride PET film)
(Lum) -Al foil film by the same method as in the example.
And laminated with PE and paper. This packaging film
The oxygen barrier properties were measured in the same manner as in the examples.

Next, a method for measuring the oxygen permeability will be described. -Oxygen transmission rate measurement method The oxygen transmission rate of the prepared gas barrier film is measured by an oxygen transmission rate measuring apparatus (OX-TRANS manufactured by Modern Controls).
100). This example shows an excellent barrier property of about 0.5 cc, while Comparative Example 1-
, Is inferior.

Next, the milk was heat-sterilized and filled while the examples 1 to 5 were placed in a liquid filling machine and formed into a paper bell-shaped paper carton. The laminate configuration at this time was PE / paper / gas barrier film / PE. This sample was left open in a room at 40 ° C. and 90% RH for one month, opened, and tasted, but the taste and flavor of the milk did not change. Similarly, in Comparative Examples 1 to 4, a paper carton was formed by a liquid filling machine, milk was injected, and the container was left under the same conditions, opened, and tasted. In Comparative Example 1-, the stored milk had an oxidizing odor and was judged to be inferior in taste. In Comparative Example 1-, there was no change in the taste and flavor of the milk, but it was difficult to recycle the paper from the laminated paper carton. On the other hand, from the paper carton of the embodiment,
It was easy to recycle. When these were incinerated, in Comparative Example 1-, there was a problem that chlorine gas was generated, and in Comparative Example 1, there was a problem that Al metal remained unburned. In contrast, in this example, no problem occurred.

[0016]

Example 2 Flaky Al ₂ O ₃ (purity 99.5%) and SiO _{2 having} a size of about 3 to 5 mm were used as evaporation sources.
(Purity: 99.9%), using electron beam evaporation method
μm thick PET film (Toyobo Co., Ltd .: E510
0) An aluminum oxide / silicon oxide based thin film was formed thereon. The deposition conditions were such that the emission current of the electron gun (EB gun) was 1.5 A, and the composition was changed by changing the heating ratio. Examples 1 to 6 were produced by laminating a vapor-deposited film having a thickness of 600, 2000 A (angstrom), PE (polyester) 40 μm, and paper. The amount of oxygen permeation of this packaging film and the amount of oxygen permeation after being formed by a paper carton molder were measured. As a comparative example,
Al ₂ O ₃ + SiO ₂ composition ratio (10:90), Al ₂
A thin film having a composition of O ₃ and SiO was vapor-deposited on a PET film in the same manner as in the examples, and was further laminated with PE and paper to produce Comparative Examples 1 to. The oxygen permeability of the packaging film and the properties after being formed by a paper carton molding machine were measured. The specific gravity of the thin film is measured by a floatation method after dissolving the PET film.

In Comparative Examples 2 to 5, the oxygen barrier property was
In contrast to 5 cc or more, this embodiment shows good characteristics at 2.0 cc or less. Further, in the characteristics after molding, Comparative Example 2 was also inferior in large, whereas in this example, it was excellent at 2.5 cc or less even after molding. In the case of Examples 2-, ..., 10, 11 in which the specific gravity is within the specified range, the results are particularly excellent. In Comparative Examples 2 to 5, the characteristics after molding are 5 cc or more, whereas this example is excellent at 2.5 cc or less. Further, when the specific gravity is within the specified range, it is particularly excellent. Next, Example 2
The film of-was placed in a liquid filling machine and filled with sake while being formed into a paper carton. The laminate configuration at this time was PE / paper / gas barrier film / polyester sealant, and a polyester sealant was used instead of PE as the sealant. Here, the polyester sealant is terephthalic acid / isophthalic acid // ethylene glycol = 80/20 // 100. Place this sample in a room at 40 ° C and 90% RH for 6 hours.
Left for months. It was tasted after standing, but the taste and aroma were not different from those immediately after packaging. Using the films of Comparative Examples 2 to 5, sake was filled in the same manner as in the examples. The sake was tasted after being left in a room at 40 ° C. and 90% RH for 6 months, and the taste and aroma changed, and it was judged that the taste was inferior.

[0018]

According to the present invention, there is provided a paper carton using a gas barrier film having an aluminum oxide / silicon oxide thin film formed on a plastic substrate and a packaging material for the paper carton. The gas barrier film is characterized in that the aluminum oxide contained therein is contained in an amount of 20% by weight to 99% by weight, or
The relationship between the specific gravity of the thin film and the composition ratio of aluminum oxide in the thin film is D = 0.01A + b (D: specific gravity of the thin film, A: in the thin film). Weight percent of aluminum oxide), the specific gravity of the thin film is 1.6 ≦ b ≦ 2.2.
By forming all or part of the gas barrier film characterized by being within the range represented by the following formula, paper carton and paper with excellent gas barrier properties and excellent practical characteristics that are environmentally friendly. -A packaging material for a carton can be provided.

[0019]

[Table 1]

[0020]

[Table 2]

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toru Kotani 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyo Spinning Co., Ltd. (72) Inventor Yozo Yamada 2-1-1 Katata, Otsu-shi, Shiga Prefecture Examiner Hiroaki Hirai in the Research Laboratory of Toyobo Co., Ltd. (56) References JP-A-4-99165 (JP, A) JP-A-60-23037 (JP, A) JP-A-3-23934 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. A thin film having a composition mainly composed of aluminum oxide and silicon oxide is provided on at least one surface of a plastic base material, wherein 20 to 99% by weight of aluminum oxide is contained in the composition of the thin film, and the thin film is Wherein the specific gravity of the satisfies the following expression: D = 0.01A + b, where D: specific gravity of the thin film, A: weight% of aluminum oxide in the thin film 1.6 ≦ b ≦ 2.2 2. A paper carton, characterized by using the packaging material for paper carton according to claim 1.