JP2589499B2 - Packaging material - Google Patents

Description

The present invention relates to a packaging material suitable for use in transporting agricultural products after harvesting while maintaining the freshness thereof.

(B) Problems to be solved by conventional techniques and inventions In recent years, fresh agricultural products are more attracted to fragrance, color, freshness, etc. than nutritional components, and are sensual aspects such as chewyness, flavor, and taste. Weight is being placed on In other words, it is no exaggeration to say that the value of fresh agricultural products depends on their freshness. However, the freshness of freshly-produced agricultural products is reduced while packaging and transporting the harvested agricultural products from the producing area to the consuming area.

The decrease in freshness of fresh produce is caused by various factors. The most significant factor is ethylene gas, which is also called an aging hormone produced by fresh produce. That is, under the closed environment of packaging, the packaging container is filled with ethylene gas generated by fresh produce, acts on fresh produce, and promotes aging thereof.

In order to eliminate this factor, it is considered that an ethylene adsorbent that adsorbs ethylene gas is applied to the inner surface of the packaging material using an adhesive, and the ethylene gas generated during transportation is adsorbed on the packaging material itself. Can be However, even if the ethylene gas is once adsorbed by the ethylene adsorbent, it may be released to the outside again when the temperature of the outside air rises. This is because the movement of ethylene gas becomes active with an increase in temperature. The released ethylene gas fills the package and acts on fresh produce to promote its aging. Therefore, when the temperature of the outside air rises during transportation, the ethylene adsorbent does not function effectively, and the freshness of agricultural products may decrease.

Therefore, the present invention transports agricultural products using a packaging material in which a freshness preserving agent containing an ethylene adsorbent and another specific substance is laminated on a packaging material body, thereby increasing the temperature of the outside air during transportation. However, the present invention aims to provide a packaging material from which ethylene gas once adsorbed is not released.

(C) Means for Solving the Problems That is, the present invention relates to a polymer complex in which copper (I) chloride and aluminum chloride are coordinated to crosslinked polystyrene, and silver (I) and aluminum chloride are coordinated to crosslinked polystyrene. Polymer complex with copper (I) chloride coordinated to ion exchange resin, inorganic complex with copper (I) ion coordinated to zeolite, and copper (I) ion coordinated to γ-alumina An ethylene adsorbent selected from the group consisting of a coordinated inorganic complex and an inorganic complex in which copper nitrate is coordinated with activated carbon, a superabsorbent resin, and a valence of at least 2 or more and less A freshness retaining agent containing, as essential components, a salt of a polyvalent metal capable of taking a valence, and sodium bisulfite as a metal salt having a reduced valence by reducing the salt of the polyvalent metal in the presence of water. , On the surface of the packaging material body It relates a packaging material, characterized in that the layers.

In the present invention, the ethylene adsorbent is a polymer complex in which copper (I) chloride and aluminum chloride are coordinated to crosslinked polystyrene, a polymer complex in which silver (I) chloride and aluminum chloride are coordinated to crosslinked polystyrene, ion exchange A polymer complex in which copper (I) chloride is coordinated to a resin; an inorganic complex in which copper (I) ion is coordinated to zeolite; an inorganic complex in which copper (I) ion is coordinated to γ-alumina; An inorganic complex in which copper nitrate is coordinated with activated carbon is used alone or in combination.

A polymer complex in which copper (I) chloride and aluminum chloride are coordinated to crosslinked polystyrene can be obtained by the following method. First, styrene and divinylbenzene are mixed at an appropriate ratio and polymerized to obtain crosslinked polystyrene. When this crosslinked polystyrene is mixed with copper (I) chloride and aluminum chloride and heated, a polymer complex coordinated with the crosslinked polystyrene is obtained. The coordination site of copper (I) chloride and aluminum chloride is considered to be an aromatic ring of cross-linked polystyrene. Other ethylene adsorbents can be obtained in a similar manner.

The superabsorbent resin used in the present invention is a high-molecular polymer that absorbs and retains water at least 10 times its own weight, preferably at least 100 times its own weight, such as starch-acrylonitrile graft polymer and starch-acrylic acid. Examples include a salt graft polymer, a self-crosslinked polyacrylate, an acrylic acid-acrylonitrile copolymer, and a crosslinked polyacrylate.

Examples of the salt of a polyvalent metal having a valence of at least 2 and a lower valence used in the present invention include ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeC
l _3), cupric (CuSO _4), cupric chloride (CuCl _2), chromic acid (Cr ₂ (SO ₄₎ sulfuric _3), chromic chloride (CrCl
₃ ) etc. are used. These polyvalent metal salts are reduced by reacting with sodium bisulfite in the presence of water, and the valence of the polyvalent metal is reduced to reduce ferrous sulfate (FeSO ₄ ) and ferrous chloride (FeCl ₂ ), respectively. , Cuprous sulfate (Cu ₂ SO ₄ ), cuprous chloride (C
uCl), chromium sulfate (CrSO ₄ ), chromium chloride (Cr
Cl ₂ ). This reduction reaction of the polyvalent metal salt becomes an endothermic reaction, deprives external heat, and exerts a cooling action.

Each substance used in the present invention is blended at a desired ratio according to the state of the outside air. That is, in summer, since the outside air is at a relatively high temperature, a salt of a polyvalent metal having a valence of at least 2 and capable of taking a valence lower than that of the polyvalent metal, which cooperates to exhibit a cooling effect, It is preferable to add a large amount of sodium bisulfite and a super water-absorbing resin which is a metal salt having a reduced valence by reducing a salt of a valent metal in the presence of water.
In this case, water may be contained in the superabsorbent resin in advance. Since the outside air is relatively cold in winter,
It is preferable to mix a small amount of a substance such as a superabsorbent resin other than the ethylene gas adsorbent.

The above four substances are uniformly mixed to obtain a freshness preserving agent. The method for laminating the freshness-retaining agent on the surface of the packaging material body is as follows. For example, a method of spraying a freshness-retaining agent on a packaging material body to which an adhesive has been applied in advance and laminating the freshness-retaining agent, a method of kneading a freshness-retaining agent and an adhesive, and applying the freshness-retaining agent to the packaging material body and laminating the same Further, a method of sandwiching and laminating a freshness retaining agent (3) between a packaging material main body (1) and an ethylene gas permeable material (2) as shown in FIG. 1, and ethylene as shown in FIG. The gas permeable material (2) is shaped by embossing or the like to form a concave portion, and the concave portion is filled with a freshness retaining agent (3), and the packaging material packaging (1)
And an ethylene gas permeable material (2).

Examples of the packaging material body used in the present invention include aluminum foil, paper, synthetic resin film, and foam synthetic resin film. In addition, as the ethylene gas permeable material (2), a perforated film, paper, nonwoven fabric, or the like can be used.

(D) Action The ethylene adsorbent used in the present invention adsorbs ethylene gas, which is an aging hormone produced by fresh agricultural products. The superabsorbent resin contains water that evaporates from fresh produce or water that is manually injected. A salt of a polyvalent metal having a valence of at least 2 and lower than that, and sodium bisulfite as a metal salt having a reduced valence by reducing the salt of the polyvalent metal in the presence of water When water contained in the superabsorbent resin evaporates, the water comes into contact with the water to cause a reduction reaction, thereby exhibiting a cooling effect.

Accordingly, when the temperature of the outside air rises, the water contained in the superabsorbent resin evaporates, and a salt of a polyvalent metal having a valence of at least 2 and a valence lower than the same is provided. In the presence of water to reduce the valency and contact sodium bisulfite, which is a metal salt, to exert a cooling effect. Due to this cooling, the ambient temperature of the ethylene adsorbent does not rise, and the once adsorbed ethylene gas is hardly released.

(E) Examples Example 1 Crosslinked polystyrene (a mixture of styrene and divinylbenzene)
82.7 copolymer, macroreticular type) 12.7 g, 9.9 g of copper (I) chloride and 13.3 g of aluminum chloride are put into diversion carbon, added and stirred at 50 ° C., and diversion is performed as a solvent. Carbon was removed under reduced pressure to obtain a polymer complex in which copper (I) chloride and aluminum chloride were coordinated with crosslinked polystyrene.

10 g of this polymer complex, 7 g of superabsorbent resin and 8 g of ferric sulfate
And 5 g of sodium sulfite were uniformly mixed to obtain a freshness preserving agent.

After dispersing 30 g of this freshness preserving agent in an adhesive solution (5 g of vinyl acetate dissolved in 100 g of ethyl alcohol),
A packaging material was obtained by coating and drying on a 0.1 mm-thick aluminum foil.

Example 2 Crosslinked polystyrene (of styrene and divinylbenzene)
82.7 copolymer, macroreticular type) 12.7 g, silver (I) chloride 14.6 g and aluminum chloride 13.3 g were put into carbon disulfide, heated to reflux for 6 hours, and then subjected to carbon disulfide as a solvent. Is removed under reduced pressure and silver chloride (I) is added to the crosslinked polystyrene.
And a polymer complex coordinated with aluminum chloride.

10 g of this polymer complex, 10 g of superabsorbent resin and ferric chloride 1
0.8 g and 8 g of sodium sulfite were uniformly mixed to obtain a freshness preserving agent.

This freshness preserving agent was placed in a concave portion of a paper formed into an uneven shape by embossing. Thereafter, the aluminum foil having a thickness of 0.1 mm and the convex portion of the paper were bonded with an adhesive (vinyl acetate) to obtain a packaging material.

Comparative Example 1 A packaging material was obtained in the same manner as in Example 1, except that the polymer complex obtained in Example 1 alone was used as a freshness maintaining agent.

Comparative Example 2 A packaging material was obtained in the same manner as in Example 2, except that the polymer complex obtained in Example 2 alone was used as a freshness maintaining agent.

The following tests were performed to evaluate the freshness retention performance of the packaging materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2. First,
Using the packaging material obtained in Example 1 or the like as a bag, a package was prepared. Further, a package was prepared using an aluminum foil to which no freshness preserving agent was applied at all as a packaging material. The cut persimmon was sealed in these packages, and the time required for the cut portion of the persimmon to turn black was measured. In this case, the outside air temperature was 35
C. As a result, the package made of aluminum foil alone without the freshness preserving agent turned black after 45 minutes, the one of Example 1 after 60 minutes, and the one of Example 2 after 110 minutes. The color of Comparative Example 1 turned black after 50 minutes, and that of Comparative Example 2 turned black after 60 minutes. Therefore, it can be seen that the freshness retaining agents obtained in Examples 1 and 2 are superior to those of Comparative Examples 1 and 2 in freshness retaining performance.

(F) Effect of the Invention As described above, the ethylene adsorbent used in the present invention adsorbs ethylene gas, which is an aging hormone produced by fresh agricultural products. Then, the superabsorbent resin containing water evaporates water as the temperature of the outside air increases, and the water is a salt of a polyvalent metal having a valence of at least 2 and a valence lower than that. And sodium hydrogen sulfite, which is a metal salt having a reduced valence by reducing the salt of the polyvalent metal in the presence of water, causes a reduction reaction to exert a cooling effect. Then, the ambient temperature of the ethylene adsorbent does not rise due to this cooling action, and the once adsorbed ethylene gas is hardly released.

When a package is formed using a packaging material in which a freshness-preserving agent that produces such an effect is laminated on the packaging material body, ethylene gas is less likely to be filled in the package, and ethylene gas as an aging hormone acts on agricultural products. Less. Therefore, there is an effect that freshness of the fresh agricultural product in the package can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a packaging material according to one embodiment of the present invention, and FIG. 2 is a sectional view of a packaging material according to another embodiment. (1) ... packaging material itself, (2) ethylene gas permeable material, (3) ... freshness preservative

Claims (1)

(57) [Claims] 1. A polymer complex in which copper (I) chloride and aluminum chloride are coordinated to cross-linked polystyrene, a polymer complex in which silver (I) chloride and aluminum chloride are coordinated to cross-linked polystyrene, and a chloride is ion-exchange resin. A polymer complex in which copper (I) is coordinated, an inorganic complex in which copper (I) ion is coordinated in zeolite, an inorganic complex in which copper (I) ion is coordinated in γ-alumina, and nitric acid in activated carbon An ethylene adsorbent selected from the group consisting of copper-coordinated inorganic complexes, a superabsorbent resin, and a salt of a polyvalent metal having a valence of at least 2 or more and having a lower valence. A freshness-retaining agent containing, as an essential component, sodium bisulfite as a metal salt having a reduced valence by reducing the salt of the polyvalent metal in the presence of water, and laminating the freshness-retaining agent on the surface of the packaging material body. Characteristic packaging material.