JPH10111057A - Cold insulating material for preventing vegetables and fluts from getting frost bitten - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vegetables from getting frost bitten and daamaged even when they make direct contact with the surfase of a cold insulating material and hence keep freshness and prevent values of commodities from being lowered by setting temperature of the surface of the cold insulating material during a frozen cold storage agent being melted to a specific one. SOLUTION: A cold insulating member is constructed with a flat plate shaped container 1 for loading a cold storage agent 4 therein, a foamed resin sheet 2 laminated on at least one surface of the flat plate shaped container 1, and a bag shaped container 3 for containing the flat plate shaped container l and the foamed resin sheet 2. Since there is interposed the foamed resin sheet 2 having specific heat insulation between the flat plate shaped container 1 in which the cold storage agent 4 is loaded and the bag shaped container 3, surface temperature of the cold insulating member becomes 5 to 12 deg.C during the frozen cold storage agent 4 being melted. Thus, even when vegetables make direct contact with the cold insulating member, the vegetables are prevented from getting frost bitten to keep freshness and simultaneously prevent the value of commodities from being lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat container filled with a regenerator and a foamed resin sheet laminated on the surface of the container. The present invention relates to a cold insulator that has been raised to such an extent that it does not cause frostbite. The cold insulator of the present invention has a surface temperature of 5
It is prepared so as to be about ~ 12 ° C. Thereby,
Even if fresh vegetables being transported or stored directly touch the cooling material, they do not cause frostbite, maintain freshness and do not reduce the commercial value.

[0002]

2. Description of the Related Art Heretofore, a regenerator containing water having a large latent heat of fusion as a main component, a gelling agent, a cryogen, and a nucleating agent as required in an appropriate amount has been frequently used. Such a regenerator is usually filled in a plastic container, and the container is stored in a freezer of a home refrigerator or a commercial freezer and cooled, and the regenerator is frozen and used as a cold insulator. . The melting point of the regenerator can be appropriately set according to the purpose and application. During the melting of the regenerator, the surface of the regenerator is kept at a temperature slightly higher than the melting point of the regenerator.

[0003] In the transportation and storage of frozen foods and the like, a refrigerating material filled with a regenerator having a considerably low melting point of, for example, about -25 to -20 ° C is used. Moreover, there is no problem even if the product is in direct contact with the surface of the cold insulator at a relatively low temperature. On the other hand, the optimal temperature for transportation and storage is 0 ° C. to 10 ° C. or at most about 15 ° C., fruits such as grapes and cherries, vegetables such as asparagus, cabbage and lettuce, and the optimal temperature is about 5 to 10 ° C. Certain fruits such as apples and melons and vegetables such as tomatoes and cucumbers usually have a temperature of 0 ° C.
Alternatively, a cold insulator filled with a regenerator having a melting point slightly lower than that is used. Thereby, vegetables and fruits can be transported and stored at an appropriate temperature. However, if vegetables are transported or stored with the temperature of the refrigerating material slightly higher than the melting point of the regenerator, the vegetables will be frost bite if they are transported and stored in direct contact with the surface of the product. There is a problem that the value decreases.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem. By stacking a heat insulating sheet on the surface of a container filled with a cold storage agent, the temperature of the surface of the cold insulator can be reduced. It is an object of the present invention to provide a cold insulator having a predetermined temperature higher than that of the agent. By adopting such a configuration, during transportation and storage of vegetables and fruits,
Even if they come into direct contact with the surface of the cold insulating material, they do not cause frostbite, maintain freshness, and do not reduce the commercial value.

[0005]

The cold insulating material for preventing frostbite of vegetables and fruits according to the first invention is a flat container 1 filled with a cold storage agent 4 and laminated on at least one surface of the flat container. A cold insulator comprising a foamed resin sheet 2, a flat container and a bag-shaped container 3 for accommodating the foamed resin sheet, wherein the temperature of the surface of the cold insulator is 5 while the frozen regenerator is melted. ~ 12 ° C.

The cold insulator for preventing frostbite of vegetables and fruits according to the second invention is a flat container 1 filled with a cold storage agent 4, a foamed resin sheet 2 laminated on at least one surface of the flat container. A cold insulator made of a bag-shaped container 3 containing the flat container and the foamed resin sheet, wherein the melting point of the regenerator is -5 to 0 ° C, and the thickness of the foamed resin sheet is 0.1 mm. 5 to 2 mm, and its JIS A1412
Thermal conductivity at 30 ° C. measured by
0.1.

Further, the cold insulating material for preventing frostbite of vegetables and fruits according to the third invention is a flat container 1 filled with a cold storage agent 4, a foamed resin sheet 2 laminated on at least one surface of the flat container. A cold insulator comprising the flat container and the bag-shaped container 3 accommodating the foamed resin sheet, wherein the melting point of the cold storage agent is -5 to 0 ° C, and the temperature of the frozen cold storage agent is thawed. The temperature of the surface of the cold insulator is higher than the temperature of the cold storage agent by 5 to 12 ° C.

In the first invention, if the temperature of the surface of the cold insulator is lower than 5 ° C., frostbite may be caused when vegetables and the like are in direct contact with the cold insulator. On the other hand, when the temperature exceeds 12 ° C., the temperature of the atmosphere for transportation and storage becomes high, and the freshness cannot be sufficiently maintained. In the second invention, when the melting point of the regenerator is less than −5 ° C., the thickness of the foamed resin sheet is less than 0.5 mm, and the thermal conductivity exceeds 0.1, the temperature of the surface of the refrigerating material prevents frostbite. Not as high as you can. On the other hand, when the thickness of the foamed resin sheet exceeds 2 mm and the thermal conductivity is less than 0.01, the ambient temperature increases and freshness cannot be sufficiently maintained. Furthermore, in the third invention, if the temperature of the surface of the cold insulator is not higher than the temperature of the regenerator by 5 ° C. or more, vegetables and the like cause frostbite, and if it is higher than 12 ° C., freshness cannot be sufficiently maintained. .

In general, it is preferable that the regenerative agent freezes in a short time, requires less energy for freezing, and has a long effective cold keeping time. Practically, a mixture of water having a large latent heat of fusion and a gelling agent added thereto is frequently used. In the present invention, as the above-mentioned "cool storage agent", water is used as a main component, and a gelling agent and a cryogen are appropriately added thereto. It can be used without.

As the above-mentioned gelling agent, a water-insoluble superabsorbent polymer obtained by crosslinking a hydrophilic polymer such as carboxymethylcellulose, polyvinyl alcohol, sodium polyacrylate, or polyacrylamide can be used. In addition, natural polysaccharides such as starch, gelatin, and guar gum can also be used. This gelling agent is usually added in an amount of about 1 to 5 parts by weight, especially about 1 to 3 parts by weight, based on 100 parts by weight of the regenerator.
The viscosity of the regenerator decreases with a decrease in the amount of the gelling agent, and when the regenerator is filled in a container, for example, the handleability is improved. .

Examples of the cryogen include metal salts of inorganic acids such as sodium chloride and potassium chloride and polyhydric alcohols such as ethylene glycol and propylene glycol. These cryogens depend on the desired melting point of the regenerator,
The required amount may be added to water.

Further, when these regenerators are in a supercooled state, a long time is required for freezing and a large amount of energy is required. Therefore, a nucleating agent may be blended so as to freeze quickly near the melting point. In many cases, a nucleating agent may be added to the regenerator of the present invention if necessary. The nucleating agent serves as ice crystal nuclei for freezing the cold storage agent, and includes silver iodide, methaldehyde, α
-Inorganic or organic compounds such as phenazine, steroids can be used. In addition, as the nucleating agent, bacteria having activity as a certain nucleating agent, microorganisms such as marine phytoplankton, moss, and the like can also be used. In addition, the cold storage agent may further contain additives usually used for this type of cold storage agent, such as an antiseptic, an antifungal agent, and a color powder, in an amount that does not impair the properties thereof, if necessary. You can also.

Although the material and shape of the "flat container" are not specified, a resin container is usually used.
As a resin, it does not affect water and other cold storage components,
Further, a material which is not affected by the regenerator component can be used. Furthermore, any material can be used without particular limitation as long as it has relatively high rigidity and does not cause embrittlement even when exposed to a temperature below freezing for a long time. Examples of such a resin include polyolefins such as low-density polyethylene, high-density polyethylene, and polypropylene, and polyamides.

The flat container preferably has a large area and is relatively thin from the viewpoint of handling or cooling efficiency. Further, the surface is preferably as smooth as possible. If the surface is smooth, lamination with the foamed resin sheet is easy, and a sufficient heat insulating effect by the foamed resin sheet is exhibited. The flat container is usually manufactured by a blow molding method, but by appropriately adjusting the viscosity of the cold storage agent, the cold storage agent is easily filled into the inside of the mold while the molded product is held in the mold. be able to. In this case, the molding of the container and the filling of the cold storage agent can be efficiently performed in-line, which is advantageous in productivity.

The flat container is preferably a resin cardboard as in the fourth invention. The resin cardboard is usually formed by extrusion using polypropylene or the like, and has a structure in which a large number of flute portions forming a long space in the forming direction are continuous in a direction perpendicular to the forming direction. In many cases, the thickness is relatively thin, about 5 mm, and the cooling efficiency is high. Also, despite its thinness, the rigidity is quite high, the shape retention is excellent, and it is easy to handle.
Since it is thin and has high strength, it can be used, for example, by attaching it to the inner wall surface of a cool box for storing and transporting fresh vegetables and the like, or placing it on the bottom surface. Further, in this resin cardboard, the flute portion is filled with a regenerator, and the end portion can be easily sealed even when cut. Therefore, it can be cut into appropriate dimensions and used as a heat shield plate such as a partition plate in the above-mentioned cool box.

The "foamed resin sheet" is not particularly limited, and various conventionally known foamed resin sheets can be used. Such foamed resin sheets include foamed polyethylene, foamed polypropylene,
A sheet made of a resin foam such as foamed polyurethane and foamed polystyrene can be used. Also, a sheet made of a foam such as an ethylene vinyl acetate copolymer or an ethylene acrylate copolymer can be used. Among these, a foamed polyethylene sheet having relatively high strength and excellent in low-temperature brittleness is preferred.

Further, as the above-mentioned "bag-shaped container", a container made of a resin film can be used. The resin constituting the film is not specified, and general-purpose resins such as polyvinyl chloride, polyolefin, and polyamide can be used. However, it is usually preferable to use soft polyvinyl chloride that is frequently used for this type of application. . This bag-shaped container can be obtained by heat-sealing required portions of these resin films to form a bag.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. To 100 parts by weight of water, 30 parts by weight of sodium polyacrylate as a nucleating agent was added, and the melting point was 0%.
A refrigerating agent at ℃ was prepared. 900 × 120
The flutes of the cardboard made of polypropylene having a size of 0 × 5 mm were filled, and the following three types of cold insulators were allowed to stand still in a freezer set at −25 ° C. to freeze the regenerator.

Insulation material 1: The entire surface of one side of the cardboard filled with the above-mentioned regenerator is 30 JIS A1412.
0.038 kcal / m thermal conductivity measured at 0 ° C
A closed cell type foamed polyethylene sheet having a thickness of about 1 mm and a thickness of about 1 mm (manufactured by JSP Co., Ltd., trade name “Mirror Mat # 110”) was laminated. The laminate was further housed in a soft polyvinyl chloride bag-like container having an inner dimension substantially equal to the outer dimension of the laminate, thereby producing a cold insulator of the present invention. Insulation material 2: A cardboard box filled with the above-described regenerator was accommodated in a soft polyvinyl chloride bag-like container having an inner dimension substantially equal to the outer dimension of the cardboard to prepare an insulated material for comparison. Cold insulator 3: The cardboard filled with the above-mentioned cold storage agent was used as it is as a comparative cold insulator.

FIG. 1 is a sectional view of the cold insulator 1. 1 is a flat container made of resin cardboard, 11 is its flat part, 2 is a closed-cell foamed polyethylene sheet, 3 is a bag-like container made of polyvinyl chloride, 31 is a heat-sealed part, and 4 is a regenerator. . The freight portions 11 form independent spaces as shown in FIG. 1, and are filled with the regenerator 4 so as to substantially fill the respective spaces.

After the refrigerating agent was frozen, the above three kinds of refrigerating materials were taken out of the freezer, and allowed to stand still in an atmosphere adjusted to 30 ° C., and the temperature rise was compared. The temperature is the thermocouple fixed to the surface of the foamed polyethylene sheet of the cold insulator 1 (that is, between the foamed polyethylene sheet and the bag-like container) and the outer surfaces of the cold insulators 2 and 3 in the cold storage materials of the cold insulators 1 to 3. Was measured by This change in temperature is shown in FIG. In FIG. 2, ● represents the temperature of the regenerator of the cold insulator 1 and ○ represents the temperature of the foamed polyethylene sheet surface. ■ is the temperature of the regenerator of the cold insulator 2 and □ is the temperature of its surface. Further, ▲ indicates the temperature of the regenerator of the heat insulating material 3, and △ indicates the surface temperature.

According to the results shown in FIG. 2, the temperature of the regenerator and the temperature of the surface of the regenerator 3 made of polypropylene cardboard itself filled with the regenerator are almost the same regardless of the elapsed time. The melting of the regenerator is faster than that of the cold insulators 1 and 2, and the melting ends about 15 minutes before the cold insulators 1 and 2, and a sharp rise in temperature is observed. Therefore, when the temperature of the regenerator of the refrigerating materials 1 and 2 starts to rise from about 0 ° C. after 90 minutes, the temperature of the regenerator of the refrigerating material 3 has already risen to about 12 to 13 ° C.

In the refrigerating material 2, the temperature of the regenerating agent is maintained at a low temperature for a relatively long time as described above, while the temperature of the regenerating agent is maintained at about 4 to 5 ° C. while the regenerating agent is melted. You can see that it exceeds. Thus, even a relatively thin flexible polyvinyl chloride sheet has a certain degree of heat insulation, and the surface of the cold insulator can be set at a temperature slightly higher than 0 ° C. and about 2 to 4 ° C.

Further, it can be seen that the temperature difference between the regenerator and the surface of the expanded polyethylene sheet is as large as about 7 to 8 ° C. in the regenerator 1 which is the regenerator of the present invention while the regenerator is melting. The change in temperature of the regenerator itself is 1 and 2
However, the temperature of the surface of the foamed polyethylene sheet of the cold insulator 1 is 3 to 4 ° C. higher than the temperature of the surface of the cold insulator 2 after a lapse of 10 to 80 minutes.
It has become about. This supports the heat insulating effect of the foamed polyethylene sheet.

In the heat insulating material 1, a bag-like container made of soft polyvinyl chloride is further covered on the foamed polyethylene sheet. Therefore, the surface of the cold insulator 1 is higher than the surface of the foamed polyethylene sheet, and it is estimated that the temperature will be around 10 ° C. in consideration of the temperature of the surface of the cold insulator 2. Therefore, while keeping the freshness of vegetables and the like, even if the vegetables and the like are in direct contact with the surface of the cold insulator, frostbite can be more reliably prevented and the commercial value does not decrease. It is.

[0026]

According to the cold insulating material for preventing frostbite of vegetables and the like according to the first to third aspects of the present invention, a foamed resin sheet having a specific heat insulating property is provided between a flat container filled with a regenerator and a bag-like container. By intervening, the surface temperature can be increased as compared with a cold insulator used for transport and storage of ordinary fresh vegetables and the like. Thereby, even if vegetables and the like are in direct contact with the cooling material, they do not cause frostbite, keeping freshness and preventing a reduction in commercial value.

As the flat container, it is particularly preferable to use a resin cardboard as in the fourth invention. This resin corrugated cardboard is made of polypropylene or the like, and has high strength even if the thickness is about 5 mm. In addition, since the cold storage agent is filled in the flutes that form a large number of independent spaces, even if the flutes are cut into appropriate sizes, the sealing of the ends is relatively easy. Therefore, if this resin cardboard is used, it is suitable for use such as storing it in a cool box used for transporting and storing fresh vegetables and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cold insulator 1 according to an embodiment.

FIG. 2 is a graph showing the difference between the temperature of the cold storage agent and the temperature of the surface of the cold storage material when the cold storage material of the present invention and another cold storage material are melted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Flat container made of resin corrugated cardboard; 11; Fret portion of resin corrugated cardboard; 2; Closed cell foamed polyethylene sheet; 3; Bag-shaped container made of polyvinyl chloride; 31; Agent.

Claims (4)

[Claims] 1. A flat container 1 filled with a regenerator 4, a foamed resin sheet 2 laminated on at least one surface of the flat container, and a bag-shaped container for accommodating the flat container and the foamed resin sheet. 3 wherein the temperature of the surface of the cold insulator is 5 to 1 while the frozen cold storage agent is being thawed.
A cold insulator for preventing frostbite of vegetables and fruits, which is at 2 ° C. 2. A flat container 1 filled with a regenerator 4, a foamed resin sheet 2 laminated on at least one surface of the flat container, and a bag-shaped container containing the flat container and the foamed resin sheet. 3, wherein the melting point of the cold storage agent is -5 to 0 ° C., the thickness of the foamed resin sheet is 0.5 to 2 mm, and the JIS A1412
Thermal conductivity at 30 ° C. measured by
A cold insulator for preventing frostbite in vegetables and fruits, characterized by having a ratio of 0.1. 3. A flat container 1 filled with a regenerator 4, a foamed resin sheet 2 laminated on at least one surface of the flat container, and a bag-shaped container for accommodating the flat container and the foamed resin sheet. 3, wherein the melting point of the cold storage agent is -5 to 0 ° C., and the temperature of the surface of the cold storage material is 5 ° C. while the frozen cold storage agent is being thawed.
A cold insulating material for preventing frostbite of vegetables and fruits, which is characterized by exceeding -12 ° C. 4. The cold insulator according to claim 1, wherein the flat container is a resin cardboard.