JP2003047399A - Freshness-retaining agent and freshness-retaining material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freshness-retaining agent capable of effectively keeping freshness of greengroceries and excellent in persistence of the effect and safety, and to provide a freshness-retaining material. SOLUTION: This freshness-retaining agent is obtained by covering a nuclear particle containing a carbonate and/or a hydrogencarbonate with a polymer porous film such as a polymethacrylic resin film. The freshness-retaining material is obtained by fixing the freshness-retaining agent on a one-dimensional, two-dimensional or three-dimensional structure preferably a three-dimensional structure of urethane foam or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freshness-retaining material and a freshness-retaining member, and more particularly to a freshness-retaining material and a freshness-retaining member which are effective in maintaining the freshness of fruits, vegetables, flowers and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for preventing a decrease in freshness of plants such as fruits, vegetables and flowers (hereinafter referred to as fruits and vegetables in the present invention) during storage, carbonated fruits and vegetables are packed. There is a method of encapsulating and sealing gas and storing fruits and vegetables in a carbon dioxide gas atmosphere.

[0003]

The method of filling carbon dioxide gas at the time of packaging fruits and vegetables has the following drawbacks. That is, since the carbon dioxide gas barrier property of a general-purpose plastic film that is generally used for packaging is low, the enclosed carbon dioxide gas gradually permeates through the packaging bag and withdraws over time. It is difficult to maintain for a long time.

[0004] In addition, pinholes are easily visible in the packaging bag due to the stalks and thorns of fruits and vegetables, but when the pinholes are exposed in the packaging bag, the encapsulating effect is significantly reduced and the initial freshness preservation effect is obtained. You can't do that.

Furthermore, when the types and sizes of fruits and vegetables that can be packed are restricted by the volume of the packaging bag or container, and a large amount of carbon dioxide gas is released at the filling work site,
There is also the risk of workers being exposed to oxygen deprivation.

The present invention solves the conventional problems such as the decrease of carbon dioxide concentration over time, the restriction at the time of packaging, and the deterioration of working environment in keeping the freshness of fruits and vegetables using such carbon dioxide. Can effectively maintain the freshness of
An object of the present invention is to provide a freshness-retaining material excellent in durability of effect and safety, and a freshness-retaining member using the freshness-retaining material.

[0007]

The freshness-retaining material of the present invention comprises:
The present invention is characterized in that core particles containing carbonate and / or hydrogen-containing carbonate are coated with a polymer porous film.

By encapsulating the freshness-retaining material of the present invention together with fruits and vegetables in a packaging system such as a packaging bag or a packaging container, a polymeric porous film is formed from the carbonate and / or hydrogen-containing carbonate in the core particles. Since the carbon dioxide gas permeates and is gradually released, the carbon dioxide concentration in the packaging system can be maintained at a high level. The freshness-retaining material of the present invention handles solid carbonates and / or hydrogen-containing carbonates instead of gaseous carbon dioxide as in the conventional case, and therefore has high safety and excellent handleability.

Further, in the present invention, since the core particles containing carbonate and / or hydrogen-containing carbonate are covered with the polymer porous film, the freshness-retaining materials collide with each other or the freshness-retaining materials collide with other members. Even when a mechanical load is applied to the surface of the freshness-retaining material due to contact with the slide or sliding, the polymer porous film protects the core particles, and dust may be generated due to the destruction of the surface layer of the core particles. To be prevented. Further, even if dust is generated from the core particles, this dust is captured by the polymer porous film and dust generation is prevented.

In the present invention, since the core particles are covered with the polymer porous film, the water repellency of the polymer porous film repels the water particles even in an environment where the core particles are in contact with the water particles. The surface will not get wet with water drops. Therefore, the fruits and vegetables are not contaminated by the fact that the carbonate and / or hydrogen-containing carbonate of the core particles inside is wet and dissolved in water.

Due to the effect of protecting the core particles of such a porous polymer membrane, the freshness-retaining material of the present invention is directly put into a packaging bag or packaging container for fruits and vegetables without packaging it in a container or the like. Therefore, a dead space originating from the container of the freshness-retaining material is not generated, and the effective volume of the freshness-retaining material can be large, so that carbon dioxide gas can be efficiently released.

In the present invention, as the carbonate and / or hydrogen-containing carbonate, an alkali metal salt and / or an alkali metal salt, specifically, lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, carbonate One or more selected from the group consisting of sodium hydrogen and potassium hydrogen carbonate can be used.

The core particles of the freshness-retaining material of the present invention may further contain an acidic compound, and in this case, the carbon dioxide releasing property can be improved by the action of the acidic compound.
In this case, carbonic acid gas is released from the mixed system of carbonate and / or hydrogen-containing carbonate powder and acidic compound powder by the action of the acidic compound, but it is exposed to high humidity by being enclosed with fruits and vegetables in actual use. In the above, water penetrates into the solid phase interface between the carbonate and / or hydrogen-containing carbonate and the acidic compound due to the hygroscopicity of the carbonate and / or hydrogen-containing carbonate and the acidic compound, and the contact efficiency of both compounds is improved. That is, since the liberation property of carbon dioxide gas is improved, it is possible to obtain a better effect of maintaining freshness.

In this case, the acidic compound is an organic acid,
One or more selected from the group consisting of phosphoric acid, monohydrogen phosphate and dihydrogen phosphate. here,
As the organic acid, one or more selected from the group consisting of ascorbic acid, citric acid, oxalic acid, tartaric acid, malic acid, glutamic acid, sugar acid, taurine, palmitic acid, stearic acid and benzoic acid and their derivatives. Is mentioned.

The core particles may be tableted. It is preferable that the average particle diameter of the core particles is 0.01 to 100 mm, the thickness of the polymer porous membrane is 0.1 to 1000 μm, and the average particle diameter of the polymer porous membrane is 0.001 to 50 μm.

This polymer porous film is, for example, a fluororesin, a polyamide resin, a polyimide resin, a polyester resin, a polystyrene resin, a polyolefin resin, a polycarbonate resin, a polysulfone resin, an acrylic resin, a cellulose resin, a vinyl chloride resin, a polyacetal resin. ,
1 selected from the group consisting of polyurethane resins or their copolymers, their copolymers and their derivatives 1
One kind or two or more kinds may be formed, and silver may be vapor-deposited on such a polymer porous film, and antibacterial property is exhibited by silver vapor deposition.

The freshness keeping member of the present invention is characterized in that such a freshness keeping material of the present invention is fixed to a one-dimensional, two-dimensional or three-dimensional structure.

Examples of the one-dimensional structure include strings, ropes, wires and rods. As a two-dimensional structure, a plate,
A sheet etc. are illustrated. Examples of the three-dimensional structure include a three-dimensional skeleton structure.

In the freshness keeping member of the present invention, the amount of the freshness keeping material fixed to the two-dimensional structure is the number of particles of the freshness keeping material per 1 cm ² of the surface area of the two-dimensional structure.
It is 0.1 to 100,000, and the amount of the freshness-retaining material fixed to the three-dimensional structure is 1 cm ³ of the volume of the three-dimensional structure.
The number of particles of the freshness-retaining material per 1 to 1,000,0
It is preferably 00.

Further, it is preferable that the freshness maintaining member is fixed to the one-dimensional, two-dimensional or three-dimensional structure with an adhesive in the state of a single particle layer to a 1000 particle layer.

The freshness-retaining member may have a freshness-retaining material fixed to one surface of the two-dimensional structure and an adhesive applied to the other surface.

The adhesive may be an organic solvent type,
A water-based or hot-melt type is exemplified.

At least a part of such a freshness maintaining member may be covered with a breathable sheet. Further, it may have a laminated structure in which the freshness retaining material according to any one of claims 1 to 12 is sandwiched between a two-dimensional structure and a breathable sheet. It may also be housed in a breathable container.

Examples of the breathable sheet include non-woven fabric, woven fabric, mesh and net. Examples of the breathable container include those made of non-woven fabric, woven fabric, mesh or net.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the freshness keeping material and the freshness keeping member of the present invention will be described in detail below.

First, the core particles of the freshness keeping material of the present invention will be described.

The carbonate and / or hydrogen-containing carbonate contained in the core particles are alkali metal salts and / or alkali metal salts, specifically, lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, carbonic acid. One or more selected from the group consisting of magnesium, sodium hydrogen carbonate and potassium hydrogen carbonate can be used.

The core particles according to the present invention may contain an acidic compound in addition to such a carbonate and / or hydrogen-containing carbonate, and by containing the acidic compound, carbon dioxide gas is released by the action of the acidic compound. It is possible to improve the sex. Further, due to the hygroscopicity of the carbonate and / or hydrogen-containing carbonate and the acidic compound, it is possible to obtain a better freshness-retaining effect.

In this case, the acidic compound may be any compound having a pKa lower than that of the carbonate and / or hydrogen-containing carbonate, and is composed of an organic acid, phosphoric acid, monohydrogen phosphate and dihydrogen phosphate. One or more selected from the group can be used, and as the organic acid, ascorbic acid, citric acid, oxalic acid, tartaric acid, malic acid, glutamic acid, sugar acid, taurine, palmitic acid, stearic acid and Examples thereof include one or more selected from the group consisting of benzoic acid and derivatives thereof. Ascorbic acid, citric acid, taurine and the like are preferable when considering use in foods.

The content of the acidic compound in the core particles is 0.1 to 99% by weight, preferably 5 to 50% by weight, based on the carbonate and / or hydrogen-containing carbonate. If this ratio is too large, the content of carbonate and / or hydrogen-containing carbonate becomes relatively small, and sufficient carbon dioxide gas releasing performance cannot be obtained. Can't get enough.

The core particles include carbonate and / or hydrogen carbonate, acidic compounds, hydroxypropyl cellulose,
Contains hydrophilic polymer compounds such as ethyl cellulose, methyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol, partially saponified vinyl acetate, alginic acid, poly (meth) acrylic acid, polyethylene glycol, polypropylene glycol, and oxyethyleneoxypropylene block polymer. Is also good. This hydrophilic polymer compound is added to improve the mechanical strength and tableting processability of the core particles, and the content in the core particles is based on the carbonate and / or hydrogen-containing carbonate. 0.1-20% by weight,
It is preferably about 1 to 10% by weight. If this ratio is too large, the content of carbonate and / or hydrogen-containing carbonate becomes relatively small, and sufficient carbon dioxide gas releasing performance cannot be obtained. If it is too small, a hydrophilic polymer compound should be contained. It is not possible to sufficiently obtain the above effect.

The core particles include not only fine particles but also powders, granules, tablets, pills, beads and the like, and powders or granules may be tableted to give tablets.

The average particle size of the core particles is 0.01 to 100.
mm It is preferable that the thickness is in the range of 0.1 to 10 mm, in order to exhibit a good carbon dioxide gas releasing property.

The shape of the core particles is not particularly limited, and any shape such as amorphous shape (crushed particles), true sphere, elliptical capsule shape, rugby ball shape, cube and cuboid can be used, but preferably true sphere. It is advantageous in terms of packing density, effective surface area, and reduction of mechanical load on fruits and vegetables.

Next, the polymer porous membrane which coats such core particles will be described.

As the polymer material for forming the polymer porous film covering the core particles, carbon dioxide gas generated from the core particles can be permeated, and the core particles are preferably prepared by spray coating of a suspension or a solution described later. It is not particularly limited as long as it can easily form the porous film to be coated, and for example, fluororesin, polyamide resin, polyimide resin, polyester resin, polystyrene resin, polyolefin resin, polycarbonate resin , Polysulfone resin, acrylic resin, cellulose resin, vinyl chloride resin, polyacetal resin, polyurethane resin and their copolymers or derivatives such as polymethacrylic acid resin can be applied.

These polymeric materials may be used alone or in combination of two or more.

The thickness of the polymer porous membrane is 0.1 to 100.
The range of 0 μm, particularly 1 to 100 μm, and particularly 1 to 50 μm is preferable in terms of high air permeability and good carbon dioxide gas releasing property. That is, when the thickness of the polymer porous film is less than 0.1 μm, the air permeability is high, but when the freshness-retaining materials collide with each other or make sliding contact with each other, the polymer porous film is destroyed and its function is improved. May be lost, 1000 μm
If it exceeds, the air permeability may be deteriorated and the carbon dioxide gas releasing property may be lowered. Therefore, it is preferable that the thickness of the polymer porous membrane is appropriately determined within the above range in consideration of membrane strength and air permeability.

The average pore size of the polymer porous membrane is not particularly limited as long as it does not allow dust derived from carbonates and / or hydrogen-containing carbonates to pass through.
001 to 50 μm, particularly preferably 0.01 to 10 μm. That is, if the average pore size of the polymer porous membrane is less than 0.001 μm, the carbon dioxide gas passage resistance may be increased and the carbon dioxide gas release property may be impaired.
If it exceeds m, dust derived from carbonate and / or hydrogen-containing carbonate of core particles may not be captured in some cases.

When the degree of porosity of the polymer porous membrane is excessively high, the strength of the polymer porous membrane is impaired and may be destroyed during the use of the freshness-retaining material. On the contrary, it is excessively low. And the passage resistance of carbon dioxide increases, which may impair the carbon dioxide releasing property. Therefore, the porous polymer membrane preferably has a porosity in the range of 3 to 90%.

The porosity of the polymer porous membrane can be determined, for example, by the following method. That is, the freshness-retaining material of the present invention is cut into two pieces with a double-edged razor and washed with water to remove the core particles inside and isolate the polymer porous membrane of the coating layer. This is immersed in ethanol, washed with water, and then put into liquid nitrogen to bring the polymer porous membrane of the coating layer into a frozen state. Using tweezers in liquid nitrogen, the polymeric porous film is separated from the core particles and recovered without destroying the internal structure of the coating layer. The porosity of the obtained polymer porous membrane is measured by the mercury injection method and the ethanol substitution hydrous weight measurement method.

In the freshness-retaining material of the present invention, since the polymer porous membrane prevents water from penetrating, core particles containing an adsorbent substance can be protected from water droplets, that is, carbonate and / or hydrogen carbonate is contained. There is also an advantage that the core particles are not wet with water. Therefore, it is preferable to select the material of the polymer porous membrane that coats the core particles so as to make water penetration as small as possible. If the thickness of the porous polymer film is to be thin and the pore size is to be large in order to increase the height, it is preferable to use a fluororesin or the like having high water repellency.

In order to form the coating layer of the polymer porous film on the core particles, a solution (hereinafter referred to as "polymer solution") of the polymer material as described above or a suspension (in this suspension) Suspensions and emulsions are also included) to the core particles by spray coating, or the core particles are immersed in this polymer solution or suspension to form a coating layer on the surface of the core particles. This coating layer forming step is repeated according to

In spray coating of the polymer solution or suspension, it is preferable to keep the core particles in a state of being flowed in an air stream because uniform spray coating can be carried out.

For example, the particle size produced by emulsion polymerization is 0.1.
For a granular core particle containing sodium carbonate and citric acid, which is convective in a cylinder in an air blow in an upward direction using an aqueous suspension of polymethacrylic acid resin particles of about μm A method of spray coating is preferable. Thus, by drying and heat-treating while continuing the convection motion, only the contact points between the polymethacrylic acid resin particles in the coating layer formed on the surface layer portion of the core particles are melted to form a porous film. be able to. In addition, when the core particles are made to flow in the air stream in this way, particularly uniform spray coating becomes possible.

In the present invention, the coating layer may be stretched by expanding the coating layer by heating and / or reducing the pressure in the coating layer forming step or after the coating layer is formed. Alternatively, a part of the coating layer may be contracted and a part thereof may be stretched by heat treatment. This stretching or shrinkage or stretching is not an essential condition, but such treatment gives excellent freshness. A holding material is obtained. An example of such a case is a case where a polytetrafluoroethylene resin is used as the polymer resin. In this case, by heating and / or reducing the pressure at the same time as or after forming the coating layer, the polytetrafluoroethylene resin layer can be stretched by expansion of internal air or the like to form a porous coating layer. Further, the coating layer may be fired in the heating step.

When forming the polymer porous film, the coating layer formed by one coating treatment (coating layer formation treatment by spraying or dipping in the above-mentioned polymer solution or suspension) The thickness also depends on the physical properties and characteristics of the polymer material that constitutes the polymer porous membrane, and for example, in the case of polytetrafluoroethylene resin, which has the property of becoming fibrous by stretching,
After forming the coating layer, a heat treatment or the like is performed to generate mud cracks in the coating layer, whereby a large air permeability can be obtained, and a fiber aggregate having a dust trapping ability can be formed in the gap between the mud cracks. Therefore, it is possible to form a layer having a thickness of 100 μm by a single coating process. However, generally, the thickness of the coating layer formed by one coating treatment is 5 μm or less, and the coating layer is divided into several coating treatments such as heat treatment or depressurization treatment and then coating treatment again. It is preferable that a heat treatment or the like is performed between coating treatments. By doing so, it is possible to suppress the generation of mud cracks, fuse only the particle contacts of the fine powder of the polymer material, and form a microporous polymer porous film having a uniform entire surface.

When the heat treatment is performed after the coating treatment,
Generally, it is preferable to carry out the reaction at a temperature lower than the melting point of the polymer material of the polymer porous membrane, since the surface porosity and porosity of the polymer porous membrane are maintained at a high level and high air permeability, that is, adsorption performance is obtained. . This heat treatment temperature has a great influence on the surface porosity and porosity (that is, the performance of the freshness-retaining material) of the polymer porous membrane to be formed, so that the dust trapping property and the carbon dioxide gas releasing property, and further protection from water droplets are provided. Although it is desired to set the temperature appropriately in consideration of the balance of performance, it is generally preferable that the temperature is lower than the melting point of the polymer material by about 0 to 100 ° C.

Further, in the polymer solution or suspension, it is possible to add a pore-forming agent, a suspension stabilizer and an emulsifier in addition to the polymer material.

Of these, the pore-forming agent may be any as long as it can be phase-separated from the polymer material at the time when the coating layer is formed on the surface of the core particles. As such a pore-forming agent, a water-soluble polymer can be used. Or, an oligomer or an oil-soluble polymer or oligomer can be exemplified. As the water-soluble polymer or oligomer,
One or more selected from the group consisting of cellulose, poly (oxyolefin), polyvinylpyrrolidone, polyvinyl alcohol, saponified polyvinyl acetate, polyacrylic acid and polymethacrylic acid, and derivatives thereof, preferably methyl cellulose. , Hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol and polypropylene glycol, and one or more selected from the group consisting of derivatives thereof. The fat-soluble polymer is Liquid paraffin may be mentioned. At least a part of these pore-forming agents is removed by extraction, evaporation, sublimation, or combustion (including firing) treatment in the coating layer forming step or after the coating layer is formed, whereby By forming pores in the removal trace, it is possible to obtain a good polymer porous membrane having improved porosity, pore size distribution, pore shape and the like.

The type and concentration of the polymer material, the pore-forming agent, and other additives in the polymer solution or suspension used for forming the coating layer are determined by the pore diameter and film thickness of the polymer porous membrane to be formed. ,
It is appropriately set according to the porosity and the like.

In the freshness keeping material of the present invention, it is possible to deposit silver on the surface of the polymer porous film thus formed by a method such as sputtering. By depositing silver, antibacterial properties are expressed on the surface of the polymer porous film, and the bacteriostatic action against the bacteria attached to the fruits and vegetables makes it possible to achieve the freshness-retaining performance at a higher level. In this case, the deposition amount of silver is selected so as not to impair the air permeability of the polymer porous film.

Since the freshness-retaining material of the present invention does not generate dust, it can be used by directly putting it in a storage bag or a storage container for fruits and vegetables etc. in a particulate form. The freshness-retaining material may be used in the form of the freshness-retaining member of the present invention fixed to a one-dimensional, two-dimensional or three-dimensional structure.

Further, it is possible to coat the freshness-retaining member or the freshness-retaining material with a breathable sheet or to store it in a breathable container before use.

Examples of the above-mentioned one-dimensional structure include linear objects and string-like objects, and examples of the two-dimensional structure include sheet-like objects and plate-like objects. As the three-dimensional structure, three-dimensional, preferably three-dimensional skeleton structure is exemplified.

Fixing the freshness-retaining material of the present invention to a cushion-like two-dimensional structure or three-dimensional structure such as a foam not only provides freshness-retaining performance but also protects fruits and vegetables from external impact and shock. In addition, a function of protecting the fruits and vegetables from a contact load and a sliding load can be obtained, which is preferable. Examples of such a structure include foamed polyolefin and polyurethane foam.

Considering the gas exchange efficiency, it is advantageous to improve the release of carbon dioxide gas by using the freshness-retaining material of the present invention in the form of particles or powder and increasing the surface area. In the case of fixing, the particles of the freshness-retaining material are fixed in a single particle layer or in a state corresponding thereto at a maximum of 1000 particle layers or less, which means that more particles are introduced and the diffusion efficiency of carbon dioxide gas is improved. It is advantageous in increasing the diffusion amount.

When the freshness-retaining material of the present invention is fixed to a two-dimensional structure such as a sheet, the fixing density is the number of particles of the freshness-retaining material per 1 cm ² of the surface area of the two-dimensional structure. , 0.1 to 100,000, especially 100 to
It is preferable that the number is 1,000 and the weight is 0.1 to 1.0 g, and when fixed to a three-dimensional structure such as a solid,
The fixed density is 1 to 1,000,000 as the number of particles of the freshness-retaining material per 1 cm ³ of volume of the three-dimensional structure,
In particular, 100 to 10,000 pieces, with a weight of 0.1 to 1.
It is preferably 0 g in order to secure good carbon dioxide gas releasing property and diffusibility.

The freshness-retaining material can be fixed to these structures by using a pressure-sensitive adhesive or an adhesive, but it may be fixed by a fusion method using heat, high frequency, or ultrasonic waves.

When the freshness-retaining material is fixed to a two-dimensional structure such as a sheet, it can be easily attached to an appropriate location such as the inner wall of a storage container by applying an adhesive on the back surface. it can.

As the adhesive, organic solvent type, water type or hot melt type can be used.

The freshness-retaining member of the present invention in which the freshness-retaining material is fixed to the structure as described above may be further covered with a breathable sheet, or may be housed in a breathable container. In this case, the breathable sheet or the breathable container is not for capturing the dust generated from the carbonate and / or hydrogen-containing carbonate of the core particles and the acidic compound powder, and the freshness-retaining material should fall off from the structure. Is to prevent. In the case of covering with a breathable sheet, the whole structure with the freshness-retaining material fixed may be wrapped, or only a part thereof may be covered.

In the freshness protection member in which the freshness-retaining material is fixed to a two-dimensional structure such as a sheet, the freshness-retaining material is covered with a breathable sheet so that the freshness-retaining material is sandwiched between the two-dimensional structure and the breathable sheet. You may.

Nonwoven fabrics, woven fabrics, meshes, and nets can be exemplified as the structure having the freshness-retaining material fixed, or the breathable sheet covering the freshness-retaining material. This does not apply as long as it has

A structure having a freshness-retaining material fixed, or a breathable container for containing the freshness-retaining material is a non-woven fabric,
Examples of the breathable container include a woven fabric, a mesh, and a net, but the breathable container is not limited thereto.

[0066]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 65 parts by weight of sodium hydrogen carbonate, 20 parts by weight of citric acid,
And 250 g of granules (60 mesh size) consisting of 15 parts by weight of hydroxypropyl cellulose are put into a powder coating device (“MP-01” manufactured by Paulec), and the bottom is supplied at an air supply temperature of 60 ° C. and an air supply air volume of 80 m ³ / hr. Rotor is a 3-blade rotor, bottom rotor speed is 30
It was operated at 0 rpm to perform convection.

8. A fine powder suspension of polymethacrylic acid resin (solid content: 20% by weight) was sprayed by a two-fluid nozzle having a diameter of 1.2 mm with the spraying direction being the tangential direction of the rotation of the bottom rotor. 150 g was sprayed at a rate of 5 g / min.

The treated particles were taken out from the powder coating apparatus and observed by an optical microscope and a scanning electron microscope image. As a result, the entire surface of the above granules was covered with a polymethacrylic acid resin fine powder having a particle diameter of about 0.1 μm. The thickness of the coating layer was calculated to be about 5 μm from the scanning electron microscope image of the cut surface.

The particles were heat-treated at 180 ° C. for about 3 minutes to melt only the polymethacrylic acid resin fine powder contacts to form a porous film. The above-mentioned coating operation was performed again on 250 g of this heat-treated product, and thereafter, heat treatment was performed in the same manner as described above to obtain a particulate carbon dioxide gas releasing freshness-retaining material.

In a surface image obtained by a scanning electron microscope, when image processing is performed using pores other than fine powder particles on the same plane of the surface layer portion, the pore diameter of the surface layer portion is 0.1 to 0.2 μm.
Calculated as m. In addition, the hole diameter becomes almost the same value as the surface layer on the same plane even if image processing is performed on the image of the cut surface,
It was confirmed that the polymethacrylic acid resin fine powder coated particles had a substantially uniform coating layer as a whole. Further, the thickness of the coating layer was calculated to be about 10 to 20 μm from the scanning electron microscope image of the cut surface. The porosity measured by the above-mentioned porosity measuring method was 70%.

A flexible polyurethane foam without a film cut into a thickness of 25 mm × 25 mm × 5 mm (Co., Ltd.)
After applying an acrylic binder to Bridgestone's "SF # 06") and removing excess binder with a roll,
The foamed freshness-retaining material obtained above was pressure-bonded onto the foam so as to cover it with an area of 1 c on one side of the foam.
About 0.1 g (the number of particles of about 100) was fixed per m ² to obtain a freshness keeping member of the present invention.

The freshness keeping performance of this freshness keeping member was evaluated by the following method.

Spinach was used as a sample of fruits and vegetables.
In a polyethylene bag having a thickness of μm, 60 g of spinach and the freshness maintaining member were placed and left at 10 ° C. for 4 days. The number of samples was 3. After 4 days, the total amount of each sample was homogenized in a homogenizer for living tissues while adding a 50% aqueous methanol solution, and a PVDF membrane (Millipore Co., 0.
After vacuum filtration with a pore size of 2 μm, the total volume is 1000 mL.
As a test liquid, the vitamin C content was measured. High-performance liquid chromatograph system (Shimadzu Corporation, LC
10A series), the column is Shimadzu SCR-102H, the mobile phase is 2 mM perchloric acid, the column temperature is 40 ° C., the detection is with an ultraviolet spectroscopic detector, and the wavelength is 245 n.
I went in m.

The results are shown in Table 1.

Comparative Example 1 The freshness of spinach was examined in the same manner as in Example 1 except that the freshness maintaining member was not inserted in the polyethylene bag, and the results are shown in Table 1.

[0077]

[Table 1]

From Table 1, in the system using the freshness keeping member of the present invention, the decrease of vitamin C is remarkably suppressed,
A good freshness retention effect was confirmed. There was no problem of dust generation from the freshness-keeping material, and no problem of deterioration of the performance of the freshness-keeping material due to water droplets.

[0079]

As described above in detail, according to the freshness-retaining material of the present invention, the freshness of fruits and vegetables can be effectively maintained, and the freshness-retaining material and the freshness-retaining material are excellent in durability and safety. A member is provided.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4B069 HA09 KA10 KB04 KC02 KC07                       KC13 KC24 KD01 KD05 KD08                 4H011 BB18 CA03 CB11 CC02 CD03

Claims (27)

[Claims] 1. A freshness-retaining material, characterized in that core particles containing carbonate and / or hydrogen-containing carbonate are coated with a polymer porous film. 2. The freshness-retaining material according to claim 1, wherein the carbonate and / or hydrogen-containing carbonate is an alkali metal salt and / or an alkaline earth metal salt. 3. The carbonate and / or hydrogen carbonate is one or more selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. The freshness-retaining material according to claim 1 or 2, wherein 4. The freshness-retaining material according to claim 1, wherein the core particles further contain an acidic compound. 5. The acidic compound is selected from the group consisting of organic acid, phosphoric acid, monohydrogen phosphate and dihydrogen phosphate.
The freshness-retaining material according to claim 4, wherein the freshness-retaining material is one kind or two or more kinds. 6. The organic acid is ascorbic acid, citric acid,
6. One or more selected from the group consisting of oxalic acid, tartaric acid, malic acid, glutamic acid, sugar acid, taurine, palmitic acid, stearic acid, benzoic acid, and derivatives thereof, according to claim 5. Freshness preservation material described. 7. The freshness-retaining material according to any one of claims 1 to 6, wherein the core particles are tableted. 8. The average particle diameter of the core particles is 0.01 to 100.
The freshness preservation material according to any one of claims 1 to 7, wherein the freshness retention material is mm. 9. The film thickness of the polymer porous film is 0.1 to 100.
The freshness-retaining material according to any one of claims 1 to 8, which has a thickness of 0 µm. 10. The polymer porous membrane has an average pore diameter of 0.00.
1 to 50 μm, characterized in that
The freshness-retaining material according to any one of 1. 11. The polymer porous membrane comprises fluororesin, polyamide resin, polyimide resin, polyester resin, polystyrene resin, polyolefin resin, polycarbonate resin, polysulfone resin, acrylic resin, cellulose resin, vinyl chloride resin, polyacetal resin, The freshness-retaining material according to any one of claims 1 to 10, which is formed of one kind or two or more kinds selected from the group consisting of a polyurethane resin, a copolymer thereof and a derivative thereof. . 12. The freshness-retaining material according to any one of claims 1 to 11, wherein silver is vapor-deposited on the polymer porous film. 13. A freshness-retaining member, characterized in that the freshness-retaining material according to any one of claims 1 to 12 is fixed to a one-dimensional structure. 14. A freshness-retaining member, characterized in that the freshness-retaining material according to any one of claims 1 to 12 is fixed to a two-dimensional structure. 15. The amount of the freshness-retaining material fixed to the two-dimensional structure is 0.1 to 100,000 as the number of particles of the freshness-retaining material per 1 cm ² of the surface area of the two-dimensional structure.
The freshness retention member according to claim 14, wherein the number is zero. 16. The freshness-retaining member according to claim 14, wherein the freshness-retaining material is fixed to one surface of the two-dimensional structure and an adhesive is applied to the other surface. 17. A freshness-retaining member, wherein the freshness-retaining material according to claim 1 is fixed to a three-dimensional structure. 18. The amount of the freshness-retaining material fixed to the three-dimensional structure is 1 to 1,000,000 as the number of particles of the freshness-retaining material per 1 cm ³ of the volume of the three-dimensional structure. The freshness retention member according to claim 17, wherein 19. The particles of the freshness-retaining material are a single particle layer to 100 particles.
The freshness-retaining member according to any one of claims 13 to 18, wherein the freshness-retaining member is fixed to the structure in a state of 0 particle layer. 20. The freshness maintaining member according to claim 13, wherein the freshness maintaining material is fixed to the structure with an adhesive. 21. The freshness maintaining member according to claim 20, wherein the pressure-sensitive adhesive is an organic solvent-based, water-based or hot-melt-based pressure-sensitive adhesive. 22. The freshness keeping member according to claim 13, wherein at least a part of the structure to which the freshness keeping material is fixed is covered with a breathable sheet. 23. A freshness-retaining member having a laminated structure in which the freshness-retaining material according to any one of claims 1 to 12 is sandwiched between a two-dimensional structure and a breathable sheet. 24. The freshness maintaining member according to claim 22, wherein the breathable sheet is made of a non-woven fabric, a woven fabric, a mesh or a net. 25. The breathable container contains the structure having the freshness-retaining material fixed thereto.
The freshness preservation member according to any one of 3 to 24. 26. A freshness-retaining member, characterized in that the freshness-retaining material according to any one of claims 1 to 12 is housed in an air-permeable container. 27. The breathable container is made of non-woven fabric, woven fabric, mesh or net.
The freshness retention member according to 5 or 26.