JP2561225B2 - Cardboard box used for packing fruits and vegetables and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cardboard box mainly used for packing fruits and vegetables such as rapeseed and broccoli, and a method for producing the same. The present invention relates to a cardboard box provided with a film layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, polystyrene containers made of styrofoam are often used. However, the Styrofoam packaging container cannot be easily discarded after use. It cannot be incinerated as easily as a cardboard box. Many containers of fruits and vegetables that have been shipped from the market to retailers are returned to the market because retailers cannot dispose of them. For this reason, a huge amount of Styrofoam is gathered on the market and it is difficult to dispose of it. A device for reducing the volume of styrofoam and reducing its volume has also been developed, but since the device is expensive and more time-consuming than incineration, it is not widely used.

Since the cardboard box can be easily incinerated and discarded, the drawbacks of Styrofoam can be eliminated. However, if fruits and vegetables such as rapeseed are packed and transported in a cardboard packaging container, there is a drawback that the fruits and vegetables do not last long. The reason is that the corrugated paper cannot efficiently suppress the passage of gas. In order to keep fruits and vegetables for a long time, it is necessary to make the environment of the packaging container suitable for keeping freshness. MA was developed for this purpose
(Modified Atmosphere) packaging. As MA packaging, one in which a film layer such as an aluminum foil or a plastic film is provided on the surface of cardboard paper has been developed.

[0004]

The cardboard paper provided with a film layer has an optimum environment for keeping the freshness of fruits and vegetables in which the environment inside the packaging container is kept, because the permeation of carbon dioxide and oxygen is suppressed by the aluminum foil or the plastic film. There is a feature that can be. For example, it has been clarified that the packing container for rapeseed can be kept highly fresh by keeping the carbon dioxide concentration inside the container at about 5% and the oxygen concentration at about 2 to 3%.
The film layer stretched on the corrugated cardboard is required to have gas permeability that can be maintained in this environment. For example, in the case of rape blossoms, if the gas permeability is too high, the flowers will bloom in 2-3 days and the commercial value will be lost. This is because rape blossoms do not become commercial products when flowers bloom. On the other hand, if the gas permeability is too low, it will be damp and rot inside the packaging container. For this reason, if the gas permeability is too high or too low, the internal environment of the packaging container cannot be optimized to maintain the freshness, and high quality MA packaging cannot be achieved. Not just rape blossoms,
Other fruits and vegetables tend to have a similar tendency, and a comfortable gas permeability is required for MA packaging.

To achieve this, an aluminum foil or a plastic film is used as a film layer to be stretched on a cardboard paper, but since the aluminum foil has almost no gas permeability, the area to be stretched must be small. It needs to be changed to adjust the gas permeability. Since the gas permeability of plastic films varies depending on the type, it is necessary to adjust the gas permeability by adjusting the film thickness and the coating area.

These film layers can adjust the gas permeability to an optimum value, but have another troublesome drawback. It is that the film layer hinders the recycling of cardboard, despite the use of cardboard that can be effectively reused instead of Styrofoam. This is because the cardboard paper on which aluminum foil or plastic is stretched cannot be recycled as paper pulp and reused as cardboard paper. Therefore, cardboard boxes with aluminum foil or plastic film layers are
Since there is no way to discard but to incinerate, there is a drawback that important paper pulp resources cannot be effectively reused. In addition, when a cardboard box with a plastic film layer is incinerated, the plastic may damage the incinerator.

The present invention was developed for the purpose of solving these drawbacks, and an important object of the present invention is to effectively recycle a cardboard box even though fruits and vegetables can be kept highly fresh. It is intended to provide a cardboard box used for packing fruits and vegetables that can be recycled by utilizing the same, and a manufacturing method thereof.

[0008]

A cardboard box used for packaging fruits and vegetables according to the present invention and a method for manufacturing the same have the following constitution in order to achieve the above-mentioned object. Cardboard paper has a film layer on its surface that suppresses gas permeation. The film layer is a natural polysaccharide film in place of the aluminum foil or the plastic film, and the natural polysaccharide film contains alginate. The natural polysaccharide membrane can be alginate in its entirety, or it can be a mixture of alginate and pullulan. For alginate,
Preferably calcium alginate is used.

Further, according to the method of manufacturing a cardboard box used for packing fruits and vegetables of the present invention, a cardboard box is manufactured by the following steps. (1) Apply sodium alginate to the surface of cardboard paper. (2) A cardboard box coated with sodium alginate is brought into contact with an aqueous solution containing either calcium ion or magnesium ion. An aqueous solution containing either calcium ion or magnesium ion is calcium chloride, calcium carbonate, calcium hydroxide, magnesium chloride,
It can be made by dissolving magnesium carbonate, magnesium hydroxide, etc. in water. In this step, sodium alginate becomes calcium alginate or magnesium alginate and solidifies on the surface of the cardboard paper to form a natural polysaccharide film.

[0010]

The cardboard box used for packaging fruits and vegetables according to the present invention has a natural film layer applied to the surface of the cardboard paper. The film layer is a natural polysaccharide film containing alginate. The film layer of natural polysaccharide film applied on the surface of cardboard paper suppresses gas permeability and keeps it in an environment suitable for packaging fruits and vegetables. Further, the cardboard box coated with a film layer which is a natural polysaccharide film has a feature that it can be dissolved and reused as paper pulp after use, and can be effectively recycled and reused as a cardboard box.

Further, a method of applying sodium alginate on the surface of cardboard paper and contacting it with an aqueous solution containing calcium or magnesium ions to coagulate sodium alginate as alginate is a simple natural method for the surface of cardboard boxes. A film layer of a sugar film can be formed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify a cardboard box used for packaging fruits and vegetables for embodying the technical idea of the present invention, and the present invention describes a cardboard box and a manufacturing method thereof as follows. Not specified.

A cardboard box 1 used for packing fruits and vegetables shown in FIG. 1 has a shape capable of packing fruits and vegetables by forming cardboard paper into a box shape. In the cardboard box 1, it is necessary to prevent the air inside from freely leaking to the outside while the fruits and vegetables are packed. Therefore, the cardboard box 1
After storing the fruits and vegetables, tape 2
Or glue caulking on this part and seal it. Ideally, the tape 2 and the caulking material should completely block the air leakage portion of the cardboard box. However, since the cardboard box of the present invention uses cardboard paper having a property that allows gas to pass through to some extent, the tape or caulking material does not necessarily have to completely close the air leak portion in a completely sealed state.

The cardboard box of the present invention is characterized in that a unique film layer is attached to the surface of cardboard paper.
The film layer can be attached to both sides of the cardboard box, but preferably, as shown in FIG.
The natural polysaccharide film 3 is attached as a film layer to one surface of the.

The film layer deposited on the surface of the cardboard box 1 is the alginate natural polysaccharide film 3. The alginate natural polysaccharide membrane 3 has gas permeability suitable as a packaging container for fruits and vegetables. The alginate that is the natural polysaccharide membrane 3 is preferably calcium alginate. However, magnesium alginate can be used instead of calcium alginate for the natural polysaccharide membrane 3. further,
A multilayer natural polysaccharide film composed of calcium alginate and magnesium alginate can also be used. The film thickness of the natural polysaccharide film 3 is, for example, 20 to 500 μm, preferably 5
The thickness is 0 to 300 μm, and more preferably 60 to 200 μm. Increasing the film thickness of the natural polysaccharide film reduces the gas permeability, and conversely decreasing the film thickness increases the permeability. The film thickness of the natural polysaccharide film is adjusted to an optimum value depending on the kind of fruits and vegetables to be packed. However, the gas permeability varies not only with the film thickness of the natural polysaccharide film but also with the material of the natural polysaccharide film. Therefore, the thickness of the natural polysaccharide film depends on the material of the natural polysaccharide film, the type of fruits and vegetables to be packed,
It is adjusted to an optimum value in consideration of whether the natural polysaccharide film is applied on both sides or one side and the shape of the cardboard box.

On the surface of the cardboard paper,
Form a natural polysaccharide film that is calcium alginate. Example 1 (1) Sodium alginate is applied to the surface of cardboard paper. The film thickness of sodium alginate is about 100 μm
And Use a cardboard box having a basis weight of 220 g / m ² . Sodium alginate is applied to the surface of cardboard paper in the form of an aqueous solution dissolved in water. The sodium alginate aqueous solution is adjusted to have a solid content concentration of 5% by weight, for example.

The aqueous solution of sodium alginate is applied to the surface of the cardboard box using a brush. Instead of the brush, a coating roll can be used to coat the surface of the cardboard paper. It is also possible to spray an aqueous solution of sodium alginate onto the surface of the cardboard paper, or alternatively, immerse the cardboard paper in the aqueous solution of sodium alginate to apply sodium alginate to both sides of the cardboard paper. The film thickness of sodium alginate applied to the surface of the cardboard box can be adjusted by the solid content concentration of the sodium alginate aqueous solution and the application method. When sodium alginate is applied thickly to cardboard paper, the solid concentration of sodium alginate is increased to obtain high viscosity. On the other hand, when applying a thin film of sodium alginate, the concentration of sodium alginate is lowered to lower the viscosity.

(2) A cardboard paper coated with sodium alginate is dipped in an aqueous solution of calcium chloride for 3 minutes. The concentration of calcium chloride is 5% by weight. The calcium chloride aqueous solution contains calcium ions. Calcium ions replace sodium in sodium alginate to give calcium alginate. Therefore, sodium alginate becomes calcium alginate and solidifies on the surface of the cardboard box.

(3) After drying, a natural polysaccharide film of alginate, which is calcium alginate, is provided on the surface of the cardboard paper.

Example 2 In the step (2) of Example 1, a cardboard box coated with sodium alginate was
A natural polysaccharide film is formed in the same manner as in Example 1 except that the film is immersed in a 5 wt% magnesium chloride aqueous solution instead of being immersed in the calcium chloride aqueous solution. The cardboard box produced by this method has a surface coated with a natural polysaccharide film of magnesium alginate.

[Example 3] A natural polysaccharide film is formed on the surface of a cardboard box as in Example 1 except that the step (1) in Example 1 is carried out as follows. (1) Sodium alginate and an aqueous solution of pullulan, which is a natural polysaccharide film, are applied to the surface of cardboard paper.
The film thickness of the mixed solution of sodium alginate and pullulan is about 10
0 μm. Use a cardboard box having a basis weight of 220 g / m ² . Sodium alginate and pullulan are
It is applied to the surface of cardboard paper in the state of an aqueous solution dissolved in water. A mixture of 50% by weight of sodium alginate and 50% by weight of pullulan is adjusted to a solid content concentration of 5% by weight to prepare an aqueous solution.

In the cardboard boxes manufactured by the methods of Examples 1 and 2, the natural polysaccharide film contracted to some extent after drying and warped. The cardboard box manufactured by the method of Example 3 in which pullulan was added to sodium alginate and coated was:
No warpage occurred after drying. Considering the warpage, the cardboard box manufactured in Example 3 exhibited ideal physical properties. When the gas permeability of the corrugated cardboard boxes manufactured by the methods of Examples 1 to 3 was measured, it showed substantially similar characteristics. FIG. 3, FIG. 5, and FIG. 6 show the characteristics of the cardboard box manufactured in Example 3 which does not warp after drying.

The straight line plotted with □ in FIG. 3 shows the moisture permeability of the cardboard box without the film layer, and the straight line plotted with ◯ shows the moisture permeability of the cardboard box according to the present invention on which the natural polysaccharide film is formed. Is shown. As shown by this straight line, the cardboard box of the present invention can reduce the amount of moisture permeation as compared with a cardboard box without a film layer. Therefore, it is possible to prevent the inside of the cardboard box from being overdried and to keep the fruits and vegetables in a high freshness state.

However, as shown in FIG. 4, the amount of moisture permeation is such that the relative humidity on one side of the cardboard box 1 is 80%, the temperature is 30 ° C., and calcium chloride 4 is adhered to the other side of the cardboard box.
The amount of humidity permeated through the cardboard box 1 and adsorbed on the calcium chloride 4 was measured and measured.

Further, FIGS. 5 and 6 are graphs showing the amounts of permeation of carbon dioxide and oxygen. In these figures, the curve plotted with □ shows the characteristics of the cardboard box without the film layer, and the curve plotted with ◯ shows the characteristics of the cardboard box according to the present invention in which the natural polysaccharide film is formed. However, the amounts of permeation of carbon dioxide and oxygen were measured by the device shown in FIG. The measuring device shown in this figure is a 1 liter container 5
Was filled with 300 cc of carbon dioxide gas, the opening was closed with a cardboard box 1, and the carbon dioxide concentration and oxygen concentration in the container 5 were measured by gas chromatography to measure the permeation amount of carbon dioxide and oxygen.

In the cardboard box without the film layer, as shown in FIG. 5, the carbon dioxide gas in the container was reduced to 10 after about 25 minutes.
While 0 cc and 200 cc were transmitted, the cardboard box according to the present invention, even after 100 minutes,
Only 50 cc of carbon dioxide permeated. That is, the permeation of carbon dioxide was considerably suppressed by the natural polysaccharide membrane.

As for oxygen, as shown in FIG. 6, in the cardboard box without the film layer, oxygen permeated well from the outside and the oxygen concentration in the container rapidly increased. In the cardboard box manufactured in Example 3 above, the oxygen permeation was low and the oxygen concentration in the container was only slightly increased.

Furthermore, when the cardboard box produced in Example 3 was used for packing rapeseed, the rapeseed did not bloom even after storage at room temperature for 5 days, and the commercial value was not lost. By the way, the corrugated cardboard box without the film layer had no commercial value after 3 days since the rape blossoms bloomed in the same environment. Furthermore, the rapeseed in a polystyrene foam container that is currently used for packing rapeseed has lost its commercial value after 5 days when the rapeseed blooms.

[0029]

The cardboard box used for packing fruits and vegetables according to the present invention has a film layer stretched on the surface of cardboard paper, and this film layer is a natural polysaccharide film.
A cardboard box equipped with a natural polysaccharide film suppresses gas permeability to an environment suitable for maintaining the freshness of fruits and vegetables, and provides high-quality MA.
Achieve packaging. Therefore, the cardboard box of the present invention,
Achieves an extremely excellent feature that can keep fruits and vegetables fresh for a long period of time. In particular, the natural polysaccharide membrane does not allow gas to permeate at all like aluminum foil, but has a gas permeability suitable for storing fruits and vegetables, so it is necessary to adjust the area to be stretched like aluminum foil. No, and
Since sodium alginate or the like can be applied and solidified to form a film, it has a feature that it can be mass-produced easily, inexpensively and efficiently.

Furthermore, a remarkable feature of the cardboard box of the present invention is that it has excellent physical properties as a container for packing fruits and vegetables, and that it can be effectively reused by recycling used cardboard boxes many times. There is something you can do. Since the cardboard box of the present invention uses a natural polysaccharide film which is a natural product in place of the aluminum foil or the plastic film for the film layer, the cardboard paper is melted and regenerated into paper pulp after use, and this paper is used. This is because the pulp can be reused as a cardboard box many times.
Therefore, the cardboard box of the present invention realizes an extremely excellent feature that can effectively utilize paper pulp resources and can keep fruits and vegetables with high freshness.

Furthermore, the cardboard box used for packing the fruits and vegetables of the present invention can be easily discarded by incineration after use, if necessary. When it is incinerated and discarded, it does not damage the incinerator like plastic film and does not leave residue like aluminum foil. The feature is that both the cardboard box and the natural polysaccharide film can be completely incinerated and discarded.

[Brief description of drawings]

FIG. 1 is a perspective view of a cardboard box according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a cardboard box formed with a natural polysaccharide film.

FIG. 3 is a graph showing the water vapor transmission rate of a cardboard box without a film layer and a cardboard box with a natural polysaccharide film attached.

FIG. 4 is a cross-sectional view showing a moisture permeability measuring device.

FIG. 5 is a graph showing the amount of permeation of carbon dioxide in a cardboard box without a film layer and a cardboard box with a natural polysaccharide film attached.

FIG. 6 is a graph showing the amount of oxygen permeation between a cardboard box without a film layer and a cardboard box with a natural polysaccharide film attached.

FIG. 7 is a sectional view of a device for measuring the amount of permeation of carbon dioxide and oxygen.

[Explanation of symbols]

 1 ... Cardboard box 2 ... Tape 3 ... Natural polysaccharide film 4 ... Calcium chloride (for moisture permeability measurement) 5 ... Gas impermeable container

Front page continued (72) Inventor Koji Masaki 2 11-11 Nishikai, Saika-cho, Tokushima City, Tokushima Prefecture Tokushima Prefectural Industrial Technology Center (72) Yoshitaka Arai 2-11 11 Nishikai, Togashima-ku, Tokushima City, Tokushima Prefecture Shimadzu Industrial Technology Center (56) References JP-A-2-249448 (JP, A) JP 63-23158 (JP, B2)

Claims (2)

(57) [Claims] 1. A cardboard box provided with a film layer for suppressing gas permeation on the surface of cardboard paper, wherein the film layer is a natural polysaccharide film and the natural polysaccharide film contains alginate. Cardboard box used for packaging. 2. A surface of a cardboard paper is coated with sodium alginate and brought into contact with an aqueous solution containing either calcium ion or magnesium ion, and the sodium of alginate is replaced with calcium or magnesium to form calcium alginate or alginate. A method for manufacturing a cardboard box used for packaging fruits and vegetables forming a natural polysaccharide film of magnesium.