Oxygen absorber, oxygen absorber package, and food package

Abstract

To enhance the oxygen absorptive ability of a particulate deoxidant.SOLUTION: A deoxidant 20 includes a core part 21 containing a porous carrier and an oxygen absorption composition carried by the carrier and a layering shell part 22 that contains hydrophilic silica particles and covers the surface of the core part. The oxygen absorption composition includes a liquid formulation containing an oxygen absorptive substance, an alkaline compound made of a calcium compound, and a transition metal compound. C / Si>0.4 and Ca / Si>0.1 are satisfied, where C / Si is a ratio of an atomic number concentration % of carbon to an atomic number concentration % of silicon and Ca / Si is a ratio of an atomic number concentration % of calcium to an atomic number concentration % of silicon each in the shell part measured by energy dispersive X-ray analysis. The hydrophilic silica particles have an average particle diameter of less than 7 μm.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an oxygen absorber and an oxygen absorber package, as well as a food package containing the oxygen absorber package and a method for producing the oxygen absorber. [Background technology]

[0002] One method for long-term food preservation is to enclose an oxygen absorber in the food packaging. In this method, the food and the oxygen absorber are enclosed in a gas-barrier sealed bag or container, and the oxygen in the sealed container is absorbed by the oxygen absorber, maintaining a substantially oxygen-free atmosphere inside the sealed container, thereby suppressing quality deterioration due to oxidation and the growth of bacteria and microorganisms.

[0003] There are two main types of oxygen absorbers currently in common use: inorganic oxygen absorbers that use iron as the main ingredient, and organic oxygen absorbers that use ascorbic acid-based oxygen absorbing substances as the main ingredient. These are used depending on the purpose and the food they are intended for, but in recent years, there has been an increasing need for products to be placed through metal detectors, so there has been an increasing demand for organic oxygen absorbers that can be placed through metal detectors.

[0004] Organic oxygen absorbers have the disadvantage of absorbing oxygen more slowly than iron-based oxygen absorbers. When using oxygen absorbers to improve the shelf life of food, it is desirable to reduce the oxygen concentration to less than 0.1% within 24 hours in order to prevent the growth of mold, which grows in as little as 24 to 48 hours. However, it is not easy to meet this requirement with organic oxygen absorbers. Therefore, in order to increase the oxygen absorption rate in organic oxygen absorbers, it has been proposed to add a reaction catalyst or a reaction promoter that promotes the oxidation reaction of the oxygen absorbing substance, or to add an alkaline compound to achieve an optimal pH (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3541859 Summary of the Invention [Problem to be solved by the invention]

[0006] Based on the above prior art, the inventors have succeeded in increasing the oxygen absorption capacity by a different approach.

[0007] An object of the present invention is to further improve the oxygen absorption capacity of a granular oxygen absorber. [Means for solving the problem]

[0008] A first aspect of the present invention includes a porous support and an oxygen absorbing composition supported on the support. Spherical or oval The oxygen absorber comprises a core portion and a layered shell portion that contains hydrophilic silica fine particles and covers the surface of the core portion. The oxygen absorbing composition includes a liquid agent containing an oxygen absorbing substance, an alkaline compound consisting of a calcium compound, and a transition metal compound. When the ratio of the carbon atomic concentration % to the silicon atomic concentration % measured by energy dispersive X-ray analysis of the shell portion is defined as C / Si, and the ratio of the calcium atomic concentration % to the silicon atomic concentration % is defined as Ca / Si, C / Si > 0.4 and Ca / Si > 0.1. The hydrophilic silica fine particles have an average particle size of less than 7 μm.

[0009] A second aspect of the present invention is an oxygen absorber package in which the oxygen absorber according to the first aspect is housed in a breathable packaging material. A third aspect of the present invention is a food package comprising the oxygen absorber package according to the second aspect and a packaging container in which the oxygen absorber package and food are sealed. [Effects of the Invention]

[0010] According to the present invention, the oxygen absorbing capacity of the granular oxygen absorber can be further improved. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an oxygen absorber package according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the oxygen absorber according to the embodiment. [Figure 3] 2 is a cross-sectional image of the oxygen scavenger according to the example taken by an electron microscope. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 is a diagram showing an oxygen absorber package 1 according to this embodiment. The oxygen absorber package 1 includes a breathable packaging material 10 and an oxygen absorber 20 housed in the packaging material 10.

[0013] FIG. 2 shows a schematic cross-sectional view of oxygen absorber 20. Oxygen absorber 20 is a powder with a core-shell structure having a core 21 and a shell 22 that covers core 21. In this specification, "powder" means an aggregate that is composed of a large number of fine particles and maintains fluidity as a whole. Therefore, a powder in this specification does not include a powder in which fine particles adhere to each other as a whole to form a single solid tablet.

[0014] The core portion 21 contains a porous support and an oxygen-absorbing composition supported on the support. The support may be any porous particle capable of supporting the oxygen absorbing composition. Usually, the oxygen absorbing composition is impregnated into the support, thereby supporting the oxygen absorbing material on the support. As the support, for example, one or more types selected from activated carbon, zeolite particles, bentonite particles, activated alumina particles, activated clay, calcium silicate particles, and diatomaceous earth can be used.

[0015] The oxygen absorbing composition contains a liquid agent containing an oxygen absorbing substance, an alkaline compound consisting of a calcium compound, and a transition metal compound. By preparing such an oxygen absorbing composition, a sufficient oxygen absorption rate can be obtained.

[0016] The liquid preparation containing an oxygen absorbing substance may be an oxygen absorbing substance that is liquid at room temperature (5 to 35°C), or may be a solution containing a liquid or solid oxygen absorbing substance. The oxygen absorbing substance is the main component of the oxygen absorbing composition and is a substance that absorbs oxygen. The oxygen absorbing substance may be, for example, a compound that consumes and absorbs oxygen by oxidizing itself. In this embodiment, an oxygen absorbing substance that is liquid at room temperature or dissolved in a solvent can be used. Such an oxygen absorbing substance is, for example, one or more compounds selected from the group consisting of glycerin, 1,2-glycol, and sugar alcohols. Specific examples of 1,2-glycols include ethylene glycol and propylene glycol. Specific examples of sugar alcohols include erythritol, arabitol, xylitol, adonitol, mannitol, and sorbitol.

[0017] When the liquid preparation is a solution of an oxygen absorbing substance, examples of the solvent in which the oxygen absorbing substance dissolves include water; lower aliphatic alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, secondary butanol, tertiary butanol, and tertiary amyl alcohol; glycols such as ethylene glycol, propylene glycol, and trimethylene glycol; phenyl, etc.

[0018] The oxygen absorbing substance may be any of the above compounds, either singly or in combination. By incorporating the oxygen absorbing substance into the liquid preparation, the dispersibility with the carrier and the alkaline compound is improved, making it easier to obtain oxygen absorbing performance.

[0019] The amount of the oxygen absorbing substance is usually 80 to 200 parts by mass, or may be 100 to 180 parts by mass, per 100 parts by mass of the support. When the amount of the oxygen absorbing substance is within this range, it tends to be easier to obtain an oxygen scavenger with appropriate oxygen absorption capacity.

[0020] The oxygen absorbing substance may require water for the reaction of absorbing oxygen. Therefore, even if the oxygen absorbing substance itself is liquid at room temperature, water can be added to the liquid formulation as needed. The amount of water added as needed is usually 0 to 80 parts by mass, or may be 20 to 60 parts by mass, relative to 100 parts by mass of the oxygen absorbing substance. The amount of water is usually 0 to 90 parts by mass, or may be 20 to 70 parts by mass, relative to 100 parts by mass of the support.

[0021] An alkaline compound is a compound that forms an alkaline aqueous solution when dissolved in water. When the oxygen absorbing substance has a hydroxyl group, the alkaline compound ionizes the hydroxyl group, activating the oxygen absorption reaction. In the state of the oxygen absorbing composition, a portion of the alkaline compound is often dissolved in a liquid agent containing the oxygen absorbing substance. The alkaline compound can be a hydroxide, carbonate, bicarbonate, triphosphate, diphosphate, etc. of an alkali metal or alkaline earth metal. Specific examples of alkaline compounds made of calcium compounds include calcium hydroxide and calcium carbonate, with calcium hydroxide being particularly preferred. This is because calcium hydroxide forms a soluble complex with glycerin, which facilitates the promotion of the oxidation reaction.

[0022] The amount of the alkaline compound is usually 90 to 300 parts by mass, or may be 150 to 250 parts by mass, per 100 parts by mass of the support. When the amount of the alkaline compound is within this range, it tends to be easier to obtain an oxygen scavenger with appropriate oxygen absorption capacity. In addition, alkaline compounds such as calcium hydroxide have the property of solidifying when mixed with a liquid such as water. By mixing a porous support, alkaline compound, and water in an appropriate ratio, the mixture can be formed into a self-sufficient spherical or oval sphere, forming the core.

[0023] A transition metal compound is a compound containing a transition metal element and is added to promote the oxygen absorption reaction of an oxygen absorbing substance. In the state of an oxygen absorbing composition, the transition metal compound is often dissolved in a liquid containing the oxygen absorbing substance. Specific examples of transition metal elements include iron, cobalt, nickel, copper, zinc, and manganese. The transition metal compound may be, for example, a transition metal halide, sulfate, nitrate, phosphate, carbonate, organic acid salt, oxide, hydroxide, or chelate compound. The transition metal compound may also be a double salt containing a transition metal element. The transition metal compound may be one or more compounds selected from the group consisting of copper(I) chloride, copper(II) chloride, copper(II) sulfate, copper(II) hydroxide, copper(I) oxide, copper(II) oxide, manganese(II) chloride, manganese(II) nitrate, manganese(II) carbonate, manganese(II) sulfate, and nickel(II) chloride.

[0024] The amount of the transition metal compound is usually 10 to 70 parts by mass, or may be 30 to 50 parts by mass, per 100 parts by mass of the support. When the amount of the transition metal compound is within this range, it tends to be easier to obtain an oxygen scavenger with appropriate oxygen absorption capacity.

[0025] The oxygen-absorbing composition may further contain a binder to facilitate the formation of the core portion 21. The binder may be gum arabic, polyvinyl alcohol, sodium alginate, gelatin, cellulose, etc. The amount of the binder is usually 0 to 30 parts by mass, and may be 10 to 20 parts by mass, per 100 parts by mass of the support.

[0026] The oxygen absorbing composition may further contain other substances as necessary. Examples of such other substances include catechol-based compounds that improve oxygen absorption performance. The amount of such other substances is usually about 30 parts by mass or less per 100 parts by mass of the support.

[0027] The core 21 can be obtained by granulating a mixture containing the support and the components constituting the oxygen-absorbing composition. The components constituting the oxygen-absorbing composition may be mixed together or separately. The alkaline compound contained in the oxygen absorbing composition contained in the core portion solidifies in the presence of water, and therefore forms an alkaline reaction field for improving oxygen absorption performance while also acting as a solidifying agent for forming the core portion. The mixer used for mixing is not particularly limited, and may be, for example, a rotating container mixer such as a cylindrical type or V-type, or a fixed container mixer such as a ribbon type, horizontal screw type, paddle type, or planetary motion type, or two or more types may be used in combination. In particular, the use of a fixed container mixer is preferred because stirring and granulation is performed by high-speed stirring. Granulation can be carried out by the above-mentioned stirring granulation using a stirring mixer or an extrusion granulation method using a screen with predetermined openings. Among these, stirring granulation using a stirring mixer, which can produce spherical granules, is preferred.

[0028] The shell portion 22 is mainly composed of hydrophilic inorganic fine particles, and coats the periphery of the core portion 21 in a layer form. Hydrophilic inorganic fine particles are water-insoluble particles containing a hydrophilic inorganic substance as a main component. Hydrophilic inorganic fine particles usually contain 50 mass% or more of the hydrophilic inorganic substance based on the total mass of the particles. The hydrophilic inorganic substance preferably contains silicon (Si) as an element, and examples thereof include hydrophilic silicon dioxide (SiO), calcium silicate hydrate, and aluminum silicate. In this embodiment, of the above, hydrophilic silicon dioxide, that is, hydrophilic silica fine particles are used.

[0029] The surface of the core 21 is usually formed with minute irregularities, and the small hydrophilic silica particles easily enter the recesses on the core surface, which is thought to significantly increase the surface area of ​​the oxygen absorber 20 and improve its oxygen absorption capacity. In the present invention, the average particle size of the hydrophilic silica fine particles is defined as the value of the secondary particle diameter measured by laser diffraction.

[0030] The pore volume of the hydrophilic silica microparticles can be 0.5 mL / g or more. When the pore volume of the hydrophilic silica microparticles is 0.5 mL / g, the oxygen absorption capacity of the oxygen absorber can be enhanced. It is believed that hydrophilic silica microparticles with a large pore volume are more likely to absorb the oxygen absorbing composition located near the surface of the core portion 21. In this case, the shell portion 22 contains the same alkaline compound as the alkaline compound contained in the core portion. When an oxygen absorbing composition (particularly an oxygen absorbing substance) is absorbed into hydrophilic silica fine particles, the contact area between the oxygen absorbing substance and oxygen in the environment increases, which is thought to result in improved oxygen absorption capacity. From the same viewpoint, the pore volume of the hydrophilic silica microparticles can be 0.8 mL / g or more, or 1.2 mL / g or more. The upper limit of the pore volume is not particularly limited, but can be, for example, 10 mL / g or less. In the present invention, the pore volume is defined as a value measured by nitrogen adsorption method or mercury intrusion method. Therefore, it is sufficient that the pore volume measured by at least one of the nitrogen adsorption method and mercury intrusion method is within the above-mentioned numerical range.

[0031] The silica fine particles exemplified above can be produced by a conventional method, or can be obtained by appropriately selecting from commercially available products.

[0032] When the oxygen absorber 20 is produced by agitation granulation, a known agitation mixer equipped with an agitation blade, a scraper, etc. can be used. The stirring mixer is preferably a vertical uniaxial mixer, and specific examples include Super Mixer SMP-2 (manufactured by Kawata Corporation), Intensive Mixer EL1 (manufactured by Nippon Eirich Co., Ltd.), and Triple Master TMG-1 (manufactured by Shinagawa Kogyosho Co., Ltd.). First, the materials constituting the core, excluding the liquid agent, are placed in an agitation granulator and agitated and mixed for a predetermined time (Step A). ​​The agitation time in Step A can be 5 to 15 minutes, and the agitation speed can be 3 to 8 m / sec. Next, the liquid agent is added and stirred and mixed for a predetermined time (Step B). The stirring time in Step B is 0.5 to 3 minutes, and the stirring speed is gradually increased from 1 to 5 m / s to 15 to 30 m / s. Further, when the mixture is stirred for a predetermined time, the liquid agent wets the material and causes it to aggregate, forming a roughly spherical core (Step C). The stirring time for Step C can be 0.5 to 5 minutes, and the stirring speed can be 3 to 8 m / sec. Finally, the hydrophilic silica fine particles are placed in a stirring granulator and stirred for a predetermined time, and the core portion is coated with the hydrophilic silica fine particles, thereby completing the oxygen absorber 20 having the core portion 21 and the shell portion 22 (Step D). The stirring time in Step D can be 0.5 to 2 minutes, and the stirring speed can be 3 to 8 m / sec. The above steps may be performed in the same agitation granulator, or some steps may be performed in different agitation granulators. Steps B to D are preferably performed in a uniaxial mixer, but step A, which is a mixing process of dry powder, may also be performed in a container rotary mixer.

[0033] In the above-described manufacturing method, in steps B and C, the liquid agent is placed in the form of minute droplets inside the core portion 21. Furthermore, in step D, centrifugal force acts on the core portion 21, and some of the minute droplets in which the core portion is partially dissolved move to the shell portion 22. Therefore, compared to manufacturing by extrusion granulation or the like, a larger amount of the components of the core portion 21 becomes an oxygen scavenger present in the shell portion 22.

[0034] The substances originating from the core portion that have migrated to the shell portion 22 can be measured by energy dispersive X-ray analysis (EDX). Glycerin, an oxygen absorbing substance, is detected as carbon (C), and calcium hydroxide, an alkaline compound, is detected as calcium (Ca).

[0035] When the shell portion 22 is analyzed by EDX, the ratio of the atomic concentration (%) of silicon element to the atomic concentration (%) of carbon element at a certain observation point is defined as C / Si, and the ratio of the atomic concentration (%) of silicon element to the atomic concentration (%) of calcium element at the same observation point is defined as Ca / Si, thereby obtaining semi-quantitative values ​​of the amounts of glycerin and calcium present in the shell portion 22. The position of the EDX observation point is not particularly limited, but it is preferable to set it so as to avoid the vicinity of the interface between the core portion and the shell portion, since there is a possibility that information about the core portion may be included near the interface and that an appropriate quantitative analysis of the shell portion may not be performed.

[0036] The oxygen absorber package 1 of this embodiment is completed when the oxygen absorber 20 is housed in the breathable packaging material 10 and sealed.

[0037] The food package according to this embodiment is obtained by enclosing the oxygen absorber package 1 in a packaging container containing food and sealing it. The oxygen absorber package 1 can also be suitably used for foods that undergo quality inspection using a metal detector. In the food package according to this embodiment, the type of packaging container is not particularly limited as long as it can be sealed, and can be appropriately selected from those commonly used in the field of food packaging. Examples of packaging containers include bags, deep-draw packages, tray packages, stretch packages, etc.

[0038] The oxygen scavenger according to this embodiment will be further explained using examples, although the technical scope of the present invention is not limited to the specific contents of these examples.

[0039] Example 1 7.2 parts of activated carbon, 15.6 parts of calcium hydroxide, and 1.2 parts of cellulose were added to a stirring mixer, and step A was carried out at 3.0 m / sec to obtain 24 parts of powder. The powder was confirmed to be free of lumps and a uniform gray color. Next, a liquid mixture of 10.5 parts of glycerin, 3.1 parts of copper (II) sulfate, and 4.2 parts of water was added, and Step B was carried out at 18.0 m / s. After confirming that there were no lumps or clumps in the wet powder, Step B was completed. Furthermore, step C was carried out at 5.0 m / sec. Step C was completed when it was visually confirmed that the particle surfaces were wetted, a black gloss was observed, and spherical aggregation had occurred. As a result of the above, 41.8 parts of cores were obtained.

[0040] Next, 2.1 parts of hydrophilic silica fine particles, Silopage 720 (manufactured by Fuji Silysia Chemical Ltd.), were added to the agitator mixer, and step D was carried out at 5.0 m / s. After confirming that there were no more silica particles scattered within the mixer, step D was terminated. As a result of step D, the hydrophilic silica particles uniformly coated the periphery of the wet core portion on the surface, forming a shell portion. In this way, an oxygen absorber of Example 1 having a core-shell structure was obtained.

[0041] Example 2 The oxygen absorber of Example 2 was obtained in the same manner as in Example 1, except that the type and amount of hydrophilic silica particles used was 2.1 parts of NIPGEL AZ200 (manufactured by Tosoh Silica Corporation), which has a different average particle size. (Comparative Example 1) An oxygen scavenger of Comparative Example 1 was obtained in the same manner as in Example 1, except that the type and amount of hydrophilic silica particles used was 2.1 parts of NIPGEL AY603 (manufactured by Tosoh Silica Corporation) which has a different average particle size.

[0042] (Comparative Example 2) The oxygen absorber of Comparative Example 2 was obtained in the same manner as in Example 1, except that the core portion was not coated with hydrophilic silica fine particles. That is, the oxygen absorber of Comparative Example 2 is formed only by a core portion and does not have a shell portion.

[0043] The oxygen absorbers of the Examples and Comparative Examples were evaluated as follows. (oxygen absorption capacity) 2.0 g of the oxygen absorber according to each example was placed in a bag (60 mm long, 60 mm wide) made of breathable packaging material to prepare an oxygen absorber package according to each example. The breathable packaging material used was a laminated material with a layer structure of polyethylene terephthalate / polyethylene / paper / polyethylene. Absorbent cotton soaked in 10 mL of 44% sucrose aqueous solution was placed in a bag-shaped packaging container with oxygen barrier properties. The oxygen absorber package according to each example was then placed in the packaging container and sealed under a roughly vacuum. 500 mL of air was then injected into the packaging container using a syringe, and the container was resealed to obtain the food package according to each example. This resulted in a water activity of 0.95 within the packaging container. Water activity refers to the proportion of free water in the water content of a system, and a water activity of 0.95 simulates the condition of high-moisture foods such as cheese, ham, and sausages being stored inside. The food packaging of each example was left in an atmosphere at 25° C. After 24 hours, the oxygen concentration inside was measured using a needle-type oxygen concentration meter. A low oxygen concentration means a high oxygen absorption capacity. The oxygen concentration 24 hours after sealing is widely known as a guideline for effectively preventing the growth of mold, bacteria, etc. in food packages, with less than 0.1% being most preferable, and 1% or less being within the practical range.

[0044] (Average particle size) Based on the General Rules for Sieving Test Methods (JIS Z 8815-1994), the sieve particle size of each oxygen absorber was measured using JIS test sieves of 2.8 mm, 2.0 mm, 1.0 mm, and 0.5 mm (manufactured by Okutani Wire Mesh Manufacturing Co., Ltd., JIS Z 8801-1:2019). The sieve particle sizes were plotted logarithmically, and the median diameter (D50) of each example was calculated.

[0045] (Cross-section observation of oxygen scavenger particles) Common methods for preparing cross-sectional samples include, for example, ion milling at room temperature and block cutting using a microtome. However, these methods are likely to result in the evaporation of liquid components such as glycerin and water. Therefore, it is difficult to say that a sample reflecting the actual form of the deoxidizer according to the present invention can be obtained, which is undesirable. Therefore, observation samples of each deoxidizer were prepared using a cross-section polisher under cryo-conditions. The cross-sectional images were obtained using a field emission electron microscope at an accelerating voltage of 10 kV, a sample stage temperature of about -80°C, and a magnification of about 80x to 1000x. 3 shows a cross-sectional photograph of the oxygen absorber according to Example 1. It can be seen that the shell portion 22 is formed relatively uniformly around the approximately spherical core portion 21.

[0046] (Energy dispersive X-ray analysis EDX analysis) EDX analysis was performed on the cross section of each oxygen absorber under conditions of an acceleration voltage of 10 kV and a sample stage temperature of approximately -80°C. Elemental quantitative analysis was performed using the ZAF method, and the ratio of the atomic concentration % of silicon element to the atomic concentration % of carbon element at 15 observation points on the cross section of the shell was calculated as C / Si, and the ratio of the atomic concentration % of silicon element to the atomic concentration % of calcium element was calculated as Ca / Si. Table 1 shows information about the shell part of each example, and Table 2 shows the evaluation results of each example.

[0047] [Table 1]

[0048] [Table 2]

[0049] As shown in Table 2, the oxygen absorbers of each Example exhibited superior oxygen absorption performance compared to the Comparative Examples, and in particular, Example 1 met the requirement of "oxygen concentration of less than 0.1% 24 hours after sealing," which is a guideline for suitably preventing the growth of mold, bacteria, etc. in food packages. Example 2 also had an oxygen concentration of less than 1% 24 hours after sealing, demonstrating oxygen absorbing performance sufficient for practical use.

[0050] In Examples 1 and 2 and Comparative Example 1, the liquid preparation containing the oxygen absorbent was absorbed into the shell portion, which increased the contact efficiency between the oxygen absorbing substance and oxygen in the environment, and this is thought to have improved the oxygen absorption capacity compared to Comparative Example 2, which did not have a shell portion. In other words, the presence of a certain amount or more of the oxygen absorbing substance and alkaline compound derived from the core portion in the shell portion is thought to be an indicator of high oxygen absorption performance in an oxygen absorber having a core-shell structure. Considering the measured values ​​of C / Si and Ca / Si and triple the standard deviation (3σ) in Examples 1 and 2 and Comparative Example 1, it is considered preferable that C / Si is greater than 0.4 and Ca / Si is greater than 0.1, and more preferably that C / Si > 0.6 and Ca / Si > 0.3. In addition, since there is no particular disadvantage caused by the amount of oxygen absorbing substance and alkaline compound contained in the shell portion being too large, there is no need to set an upper limit to the above numerical range.

[0051] Although the C / Si and Ca / Si ratios were within the preferred ranges, Comparative Example 1 did not exhibit sufficient oxygen scavenging performance. This was thought to be because the contact efficiency between the shell surface and air changed depending on the average particle size of the hydrophilic silica microparticles. From the results of the Examples and Comparative Examples, it was considered that in order to achieve good oxygen absorption performance, it was also necessary for the average particle size of the hydrophilic silica fine particles forming the shell portion to be less than 7 μm. The contact efficiency increases as the average particle size of the hydrophilic silica fine particles decreases, and there is no particular disadvantage to an average particle size that is too small, so there is no need to set a lower limit to the above numerical range.

[0052] The shell portion 22 absorbs and retains the liquid agent that migrates from the core portion 21, but the surface of the oxygen absorber in each example remained relatively dry. This is thought to be because the amount of liquid agent that migrated was less than the absorption capacity of the shell portion. As a result, the oxygen absorbers in each example did not become sticky and remained easy to handle. Furthermore, because they were in a particulate form, they also had good flowability and bulk density. These characteristics are effective for efficiently filling oxygen absorbers into breathable packaging and for forming breathable packaging into small pouches.

[0053] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes and combinations within the scope that do not deviate from the gist of the present invention are also included.

[0054] For example, in the above embodiment, an example was described in which the alkaline compound contained in the core portion is moved to the shell portion by stirring granulation or the like, so that the core portion and the shell portion contain the same alkaline compound. However, instead of this, the oxygen absorber may be formed by previously incorporating the same alkaline compound as the core portion into the material for forming the shell portion. [Industrial Applicability]

[0055] INDUSTRIAL APPLICABILITY The present invention can be used in oxygen absorber packages and food packages that improve the shelf life of foods and the like. [Explanation of symbols]

[0056] 1. Oxygen absorber packaging 10 Packaging material 20. Oxygen absorber 21 Core 22 Shell part

Claims

1. a porous support and a spherical or oval-spherical core portion containing the oxygen absorbing composition supported on the support; a layered shell portion containing hydrophilic silica fine particles and covering the surface of the core portion; Equipped with The oxygen absorbing composition includes a liquid agent containing an oxygen absorbing substance, an alkaline compound including a calcium compound, and a transition metal compound, wherein, when the ratio of the atomic concentration % of carbon to the atomic concentration % of silicon in the shell portion measured by energy dispersive X-ray analysis is defined as C / Si and the ratio of the atomic concentration % of calcium to the atomic concentration % of silicon is defined as Ca / Si, C / Si > 0.4 and Ca / Si > 0.1; The average particle size of the hydrophilic silica fine particles is less than 7 μm. Oxygen absorber.

2. C / Si>0.6 and Ca / Si>0.3; The oxygen scavenger according to claim 1.

3. The oxygen absorber according to claim 1 or 2 is contained in a breathable packaging material. Oxygen absorber packaging.

4. The oxygen absorber packaging body according to claim 3, a packaging container in which the oxygen absorber package and food are sealed; Equipped with Food packaging.

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