JPH024473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sealed container for fruits and vegetables that has excellent water vapor permeability, appropriate oxygen gas and carbon dioxide gas permeability, and also has self-shape retention.

[Prior Art] Conventional sealed containers for fruits and vegetables are obtained by aging sheets of thermoplastic resin having relatively excellent rigidity, such as hard vinyl chloride resin or stretched polystyrene, and are used for confectionery, rice, and processed marine products. It is mainly used for packaging processed livestock products, etc., and only a small amount is used for fruits and vegetables. The reason for this is that fruits and vegetables have complex physiological actions even after they are harvested, and environmental control that is compatible with these physiological actions is necessary to maintain freshness. It was because it was difficult.

Appropriate moisture permeability is first required for fruit and vegetable packaging. For materials that allow moisture to freely pass through, such as nettle, the drying loss is significant, and depending on the type of fruit or vegetable, for example, for fresh shiitake mushrooms, a bag of 110 to 120 g in the production area may weigh 70 to 90 g in stores.
There is also often a decrease in weight. Such products look visibly worn-out and have a significant decline in product value. Conversely, when packaging with water vapor impermeable material, condensation first occurs and the film surface becomes cloudy.
Water droplets then form, and bacteria breed within these water droplets.
Accelerates decay.

On the market, regular sealed containers or 5 to 10 mm diameter
Shape-retaining containers with several perforations are also used to some extent, but since the material itself is not permeable to water vapor, condensation occurs on the sheet surface other than the perforations, and if the number of perforations is increased, The shape retention of the container is impaired and the above problem cannot be solved. The desired moisture permeability for fruit and vegetable packaging is measured using the Honeywell method and is 45 to 250 g/24 hours at 38°C and 90% RH.
It is about ^m2 .

Fruits and vegetables continue to respire even after they are harvested, and in order to maintain freshness for a long time, it is necessary to suppress respiration. To achieve this, the O ₂ in the fruit and vegetable environment must be lower than that in the atmosphere, and the CO ₂ must be higher than that in the atmosphere. It is desirable to use a packaging material that has an O ₂ permeability that is slightly insufficient for the vigorous respiration of fruits and vegetables, and a CO ₂ permeability that is slightly insufficient for sufficient CO ₂ emissions. Preferred values are oxygen permeability, isobaric method, 24hr.1atm.30℃
2000 to 20000c.c./m ² , ^carbon dioxide permeability, Litsey method, 24 hours. /5
An O ₂ concentration of ~1/20 is desirable. When the amount of oxygen is insufficient, fruits and vegetables begin to respire inorganic respiration, which promotes the generation of off-flavors.

[Problem to be solved by the invention]

However, since gases such as O ₂ and CO ₂ can freely pass through even very fine perforations, it is difficult to provide and control the perforations. Therefore, by using a thin film of breathable plastic such as polystyrene, a favorable environment for preserving fruits and vegetables can be maintained. However, films that meet these conditions are extremely thin, and external forces applied during the distribution process can cause the contents to deform.
Since there is a risk of breakage, a self-retaining container is preferable, but a thick sheet is naturally used for a sealed container to maintain shape retention, and to reduce permeability to water vapor, O ₂ and CO ₂ . There was a problem.

The present invention is intended to solve the above problems, and aims to provide a sealed container for fruits and vegetables that uses a thick plastic sheet and has water vapor, O ₂ and CO ₂ permeability suitable for packaging fruits and vegetables, and a method for manufacturing the same. do.

[Means of problem solving]

The structure of the present invention is a flange-equipped container which is formed by molding a plastic sheet with scratches formed by transferring a file-like rough surface as it is or by laminating it with a heat-fusible film having no scratches. 10 per ^cm2 to a depth where the penetrating pores reach at least 2/3 of the sheet thickness in the container or container and lid material.
It is characterized by the existence of more than one.

In the present invention, when creating scars by transferring a file-like rough surface onto a rigid plastic sheet, only non-through holes are created by controlling the grain size and pressure of the file, and the remaining thin layer is formed into a desired range. It can allow water vapor, O ₂ and CO ₂ to permeate. In addition, a large number of fine through-holes are formed in the plastic film, and then a thin coating of hot melt adhesive, low density polyethylene, ethylene-vinyl acetate copolymer, etc. with appropriate water vapor, O ₂ and CO ₂ permeability is applied to the above sheet. It may also be a composite plastic sheet laminated to a laminate.

The through hole or non-through hole of the present invention is preferably a group of scars formed by transferring a file-like rough surface, and the size of the hole, Density and depth can be adjusted. In any case, since the holes are minute, even if there are many holes, the rigidity of the plastic sheet will not be impaired. Furthermore, since the pores are minute, it is possible to provide a large number of pores, and it is possible to provide at least 10 to 50, 100, and 1000 or more per cm ² as necessary. In addition, the depth of the non-through holes varies depending on the sheet thickness, but even if the sheet is relatively thin and the material itself has excellent permeability, the depth of the non-penetrating holes should be about 2/3 or more of the sheet thickness, preferably 9 /10 or more.

A file-like rough surface is a sheet-like file such as sandpaper or cloth with abrasive grains attached, a grinding wheel with bonded abrasive grains, or a metal or other hard material with many protrusions on the surface. In other words, hard unevenness is densely packed to form a flat or curved surface.

[Effect]

In the present invention, fine pores are formed by transferring a file-like rough surface onto a thick plastic sheet by means such as pressing the file surface, and the pores form a thin layer with desirable water vapor, O ₂ and CO ₂ permeability. It has a structure that does not penetrate the plastic sheet itself, and when it is sealed, the thin layer that remains without penetrating allows water vapor, O ₂ , and CO ₂ to pass transparently between the inside and the outside air. The holes in the thick plastic sheet are so small that they do not compromise the rigidity of the packaging material itself.

[Example] Fig. 1 is an end view showing the sealed container with a lid of the present invention in an unfolded state, Fig. 2 is a sectional view showing the sealed container of Fig. 1 in a closed state with fruits and vegetables put in it, and Fig. 3 is a cross-sectional view showing the sealed container with a lid of the present invention in a closed state. It is a partially enlarged schematic diagram of a plastic sheet.

1 is a sheet in which an inner layer 3 is laminated on an outer layer 2 made of hard vinyl chloride, and is a material for a sealed container. outer layer 2
As shown in FIG. 3, a large number of through holes 4 are bored in the hole. In one embodiment of the inner layer 3, a hot melt adhesive was uniformly applied to the inner surface of the outer layer 2. Such a sheet 1 is made according to the usual manufacturing method for a sealed container,
It was molded and punched into the shape shown in FIG. 5
The main body is approximately rectangular and dish-shaped, and the lid 6 is connected to the main body 5 via a hinge 7 and coincides with the main body 5. A flange 8 axisymmetric with respect to the hinge 7 is provided around both the main body 5 and the lid 6. 9 is a rectangular rib provided at the center of the main body and the lid, and 10 is a parallel striped rib provided on the side wall of the main body and the lid.
The hinge 7 has a ring shape at the center via the flange 8 when closed, but the bulge is gradually reduced at both ends so that the flange 8 of the main body 5 and the lid 6 come into close contact with each other and overlap each other.

Put fruits and vegetables into the main body 5, bend it at the hinge 7, cover the lid 6, and tighten only the flanges 8 on three sides to 90~
When heated to about 110°C, the adhesive of the inner layer 3 melts and adheres only to the heated portion, making it possible to seal. Alternatively, a normal hinge may be used and the four sides, including the flange 8 adjacent to the hinge 7, may be brought into close contact with each other. In addition, other breathable materials are used for the inner layer, and the flange 8
You can also apply adhesive to the chisel to seal it.

In this way, exchange with the outside air is performed only through the portion of the inner layer 3 that is in contact with the through hole 4, and water vapor and
Both O ₂ and CO ₂ permeability could be maintained within desired ranges. Therefore, for example, when fresh raw shiitake mushrooms were encapsulated, they maintained sufficient marketability for about 3 days at 25°C and for about 5 days at 15°C. In the case of conventional net bags, the storage limit is 1.5 days at 25°C and 3 days at 15°C, but the present invention showed an excellent freshness preservation effect.

In the case of the hot melt adhesive used for the inner layer 3 in this example, it was applied to a thickness of about 10 to 20 μm and was molded by heat pressing. It was 8μ.

When making the through holes in the outer layer 2, we used a method of transferring a file-like rough surface because it is possible to create many fine holes, but other commonly used mechanical methods, thermal A conventional method, a high-pressure discharge method, etc. may also be used.

Fig. 4 is a cross-sectional view of a rectangular deep-drawn molded container 14 using Styro sheet (trade name, biaxially stretched polystyrene sheet manufactured by Asahi Dow Co., Ltd.) with a seal lid attached, and Fig. 5 is a partially enlarged schematic of the sheet. It is a diagram. 1
1 is a non-penetrating hole, and by pressing the file surface with carefully selected grain size from the outer layer,
It was possible to provide a non-through hole with 1/8 remaining. 1
2 is the remaining thin layer. The sheet 3 having a large number of non-through holes 11 was heat pressed to form a sealed container having the shape shown in FIG. 4. Flanges 8 were provided on four sides, adhesive was applied, fruits and vegetables were housed, and then covered and tightly adhered with a seal lid film 13 having water vapor permeability and appropriate O ₂ and CO ₂ permeability. Stylo film TH is used as seal lid film 13.
(trade name, manufactured by Asahi Dow Co., Ltd.) was used. When storing fresh shiitake mushrooms in this deep squeeze container, at 25℃ it will be about 3.
It maintained sufficient marketability for 5 days at 15°C and exhibited superior freshness retention effects compared to conventional net bags, polyethylene bags, polypropylene bags, etc.

FIG. 6 is a schematic diagram showing one example of a desirable processing method for the sheet used in the sealed container of the present invention. 21
is a rubber-lined styrene roller,
A roller 22 rotates in the opposite direction at the same circumferential speed as the roller 21, and a cloth sandpaper or water-resistant sandpaper having alundum abrasive grains 23 attached thereto is pasted on the circumference. Reference numeral 24 is a polystyrene sheet having a thickness of 0.1 to 0.3 mm, which is pressed when passing between rollers 21 and 22, and a file surface is transferred to the surface to form a transfer surface 25 having a file-like rough surface. 40 mesh alundum was used as the sanding cloth. In this case, more than 90 through holes were formed per 1 cm ² of the polystyrene sheet.
Note that by increasing the number of passes, the number of through holes could be increased arbitrarily. This polystyrene sheet was used as the outer layer 2, and a hot melt adhesive was applied as an example of the inner layer 3 to produce a composite sheet 1, and the sealed container shown in FIG. 1 was formed by heat pressing. This was used for packaging fresh shiitake mushrooms and maintained its freshness enough for commercial use at 25°C for about 3 days.

In this example, when the same sheet was used, the file was 120 meshes, and the pressure was 30 kg, there were no through holes, and a sheet as shown in Fig. 5 was obtained, and when the number of passes was four, the sheet thickness was Approximately 7/8
There were an average of 1200 non-penetrating holes per ^cm2 . The deep-squeezed molded container shown in FIG. 4 formed using this sheet was also able to maintain the freshness of fruits and vegetables for a long time.

〔effect〕

According to the present invention, it is possible to provide a rigid sealed container that can maintain the freshness of fruits and vegetables for a long time.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is an end view of a sealed container, FIGS. 2 and 4 are sectional views of the sealed container, and FIGS. 3 and 5 are enlarged schematic diagrams of the sealed container material. FIG. 6 is a schematic diagram showing a method of processing a sheet for a sealed container. In the drawings, 1 is the composite sheet, 2 is the outer layer, and 3 is the composite sheet.
is an inner layer, 4 is a through hole, 5 is a main body, 6 is a lid, 7 is a hinge, 8 is a flange, 9 and 10 are ribs, 11 is a non-through hole, 12 is a remaining thin layer, 13 is a sealing lid film, 14 is a deep-drawn molded container, 21 and 22 are rollers, 23 is abrasive grains, 24 is a polystyrene sheet, and 25 is a file-like rough transfer surface.

Claims (1)

[Scope of Claims] 1. A sealed plastic container in which the container body and the lid are connected or separated, have a flange around the periphery, and have an adhesive applied to the flange, and which are not connected to the container or the container. A sealed container for fruits and vegetables, characterized in that the lid material has 10 or more non-penetrating holes per 1 cm ² reaching at least 2/3 of the sheet thickness. 2 A sealed plastic container with a flange around the periphery, in which the container body and the lid are connected or separated, and the container or the container and the lid material are laminated films, and the outer film has a film density of 10 ^{per cm2} .
1. A sealed container for fruits and vegetables, characterized in that the container has at least one through hole, and an inner film is a heat-fusible film. 3. A plastic sheet is passed between a pair of rolls with a file-like rough surface on at least one side, and the sheet with the scratch group transferred from the file-like rough surface on the plastic sheet surface is left as is or without the scratch group. A method for manufacturing a sealed container for fruits and vegetables, which is characterized by laminating the container with a heat-fusible film and molding the container.