JP7286946B2 - Oxygen absorber manufacturing method, oxygen absorber, oxygen absorber package, and food package - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an oxygen absorber, an oxygen absorber, an oxygen absorber package, and a food package.

Oxygen scavengers are sometimes enclosed in food packaging containers for long-term storage of foods. Granules obtained by granulating a liquid oxygen-absorbing substance together with a carrier are known as conventional general oxygen scavengers (for example, Patent Documents 1 to 3).

Japanese Patent No. 4821692 JP-A-2003-144112 Japanese Patent No. 3541859

However, if an attempt is made to manufacture an oxygen scavenger according to the conventional manufacturing method, it may become difficult to continuously operate the powder-liquid mixing device and the granulating device, and as a result, there is a risk of a drop in productivity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing an oxygen scavenger with excellent productivity. Another object of the present invention is to provide an oxygen absorber, an oxygen absorber package, and a food package produced by the production method.

One aspect of the present invention includes a powder-liquid mixing step of mixing a porous support and a liquid oxygen-absorbing composition to obtain a mixture, a granulation step of granulating the mixture to obtain a granule, and granulation. an adhesion step of attaching inorganic fine particles to the surface of an object to obtain composite particles, wherein the oxygen-absorbing composition contains an oxygen-absorbing substance and an alkaline compound, and constitutes the particles and the alkaline compound that constitute the porous support. Provided is a method for producing an oxygen scavenger, wherein the average primary particle size of the particles is 200 nm or more.

One aspect of the present invention includes composite particles comprising granules containing a porous support and a liquid oxygen-absorbing composition, and inorganic fine particles adhered to the surface of the granules, wherein the oxygen-absorbing composition is , an oxygen-absorbing substance and an alkaline compound, wherein the average primary particle size of the particles constituting the porous support and the particles constituting the alkaline compound is 200 nm or more.

In the present invention, the amount of the oxygen-absorbing substance is preferably 20-30 mass % based on the total mass of the granules.

In the present invention, the amount of the alkaline compound is preferably 100 to 300 parts by mass with respect to 100 parts by mass of the carrier.

In the present invention, the alkaline compound preferably contains calcium hydroxide.

One aspect of the present invention provides an oxygen absorber package comprising the above oxygen absorber and an air-permeable packaging material containing the oxygen absorber.

One aspect of the present invention provides a food package comprising the oxygen absorber package described above and a food packaging container enclosing the oxygen absorber package.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the oxygen scavenger which is excellent in productivity can be provided. According to the present invention, since sticking of raw materials is suppressed during powder-liquid mixing and granulation, continuous operation of the powder-liquid mixing device and the granulation device is possible, and productivity can be improved. Moreover, according to the present invention, it is possible to provide an oxygen absorber, an oxygen absorber package, and a food package manufactured by the manufacturing method.

Several embodiments of the invention are described in detail below. However, the present invention is not limited to the following embodiments.

[Oxygen absorber]
An oxygen absorber according to one embodiment includes composite particles comprising granules containing a porous support and a liquid oxygen-absorbing composition, and inorganic fine particles adhered to the surface of the granules. More specifically, the oxygen scavenger is a granule containing a porous carrier and a liquid oxygen-absorbing composition supported on the carrier, and inorganic fine particles adhering to the surface of the granule. and a plurality of composite particles consisting essentially of The oxygen scavenger may be powder. Here, "powder" means an aggregate composed of a large number of fine particles and maintaining fluidity as a whole. different from the mode. However, tablets obtained by compressing powder are not excluded from the oxygen scavenger of the present embodiment. The number of composite particles contained in the oxygen absorber according to the present embodiment may be, for example, 10 or more and 10000 or less per 1 g of the oxygen absorber.

The mass of each composite particle may be 0.3 mg or more, or 0.5 mg or more, and may be 10.0 mg or less, or 7.0 mg or less. Such finer composite particles tend to provide higher oxygen absorption capacity.

The support may be porous particles capable of supporting the oxygen-absorbing composition. Generally, by impregnating the carrier with the liquid oxygen-absorbing composition, the oxygen-absorbing substance and the like in the composition are supported on the carrier. The support may be, for example, a porous material derived from natural minerals such as bentonite particles, activated clay and diatomaceous earth, or a porous material derived from metal oxides such as activated alumina particles and zirconium oxide particles. In addition, the carrier may be a porous substance made of inorganic substances such as calcium silicate particles, porous silica particles (mesoporous silica particles), zeolite particles and activated carbon, or organic substances such as porous nylon particles and cellulose particles. It may be a porous substance consisting of.

The oxygen-absorbing composition contains at least an oxygen-absorbing substance and an alkaline compound.

The oxygen-absorbing substance may be liquid or solid at room temperature (eg, 5 to 35°C). When it is solid, it can be used by dissolving it in a predetermined solvent. The oxygen-absorbing substance is the main ingredient 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 itself being oxidized. In this embodiment, an oxygen-absorbing substance that is liquid at room temperature or dissolved in a solvent can be used. Oxygen-absorbing substances include polyhydric alcohols, and specific examples include 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. When the oxygen-absorbing substance is solid, the solvent in which the oxygen-absorbing substance dissolves includes, for example, water; methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, secondary butanol, Lower aliphatic alcohols such as tertiary butanol and tertiary amyl alcohol; glycols such as ethylene glycol, propylene glycol and trimethylene glycol; and phenols. These oxygen-absorbing substances can be used singly or in combination.

The amount of the oxygen-absorbing substance is usually 80 to 200 parts by weight, and may be 100 to 180 parts by weight, per 100 parts by weight of the carrier. The amount of the oxygen-absorbing substance is usually 20-30% by mass, and may be 22-28% by mass, based on the total mass of the granules. When the amount of the oxygen-absorbing substance is within these ranges, it tends to be easy to obtain an oxygen scavenger having an appropriate oxygen-absorbing capacity.

Oxygen absorbing materials may require water for the reaction to absorb oxygen. Therefore, even if the oxygen-absorbing substance itself is liquid at room temperature, water is added to the oxygen-absorbing composition as necessary. The amount of water added as necessary is usually 0 to 80 parts by mass, and may be 20 to 60 parts by mass, per 100 parts by mass of the oxygen-absorbing substance. The amount of water is usually 0 to 90 parts by weight, and may be 20 to 70 parts by weight, with respect to 100 parts by weight of the carrier.

An alkaline compound is a compound that forms an alkaline aqueous solution when dissolved in water. The alkaline compound may be particulate (ie, alkaline compound particles). When the oxygen-absorbing substance has a hydroxyl group, it is believed that the hydroxyl group is ionized by the alkaline compound, thereby activating the oxygen absorption reaction. A portion of the alkaline compound may be dissolved in the liquid oxygen-absorbing composition. The alkaline compound may be an alkali metal or alkaline earth metal hydroxide, carbonate, bicarbonate, tertiary phosphate, or secondary phosphate. Alkaline compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, radium hydroxide, lithium carbonate, sodium carbonate, selected from the group consisting of calcium carbonate, magnesium carbonate, potassium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, lithium hydrogen carbonate, tribasic sodium phosphate, tribasic potassium phosphate, dibasic sodium phosphate, and dibasic potassium phosphate It may be one or more compounds that are

The amount of the alkaline compound is usually 100 to 300 parts by mass, and may be 150 to 250 parts by mass, per 100 parts by mass of the carrier. Also, the amount of the alkaline compound is usually 10 to 50% by mass, and may be 20 to 40% by mass, based on the total mass of the granules. When the amount of the alkaline compound is within these ranges, it tends to be easy to obtain an oxygen scavenger having a suitable oxygen absorption capacity.

The average primary particle size of the particles constituting the porous support and the particles constituting the alkaline compound are both 200 nm or more. As will be described later, the productivity of the oxygen scavenger can be improved by deliberately using a porous carrier having a large average primary particle size and an alkaline compound in the production of the oxygen scavenger. The oxygen scavenger obtained as a result contains a porous carrier having constituent particles each having an average primary particle size of 200 nm or more and an alkaline compound. The average primary particle diameter of the particles constituting the porous support and the particles constituting the alkaline compound may be 250 nm or more, 300 nm or more, 350 nm or more, or 400 nm or more. It may be 500 nm or more. Although the upper limit of the average primary particle size is not particularly limited, it can be 1000 nm or less from the viewpoint that oxygen absorption performance tends to decrease when the primary particle size is too large. This upper limit may be exceeded depending on the type of particles forming the porous carrier. For example, activated carbon can have a primary particle size as large as 50 μm, and unlike other porous bodies and alkaline compounds, it generally does not form secondary particles as aggregates. The average primary particle size here can be measured by observing the granules with an SEM.

The oxygen absorbing composition can further include a transition metal compound. A transition metal compound is a compound containing a transition metal element, and is added to promote the oxygen absorption reaction of the oxygen absorbing substance. The transition metal compound may be particulate (ie transition metal compound particles). The transition metal compound may be dissolved in the liquid oxygen absorbing composition. Specific examples of transition metal elements include iron, cobalt, nickel, copper, zinc, and manganese. The transition metal compound can be, for example, a transition metal halide, sulfate, nitrate, phosphate, carbonate, organic acid salt, oxide, hydroxide, or chelate compound. The transition metal compound may be a double salt containing a transition metal element. Transition metal compounds include copper(I) chloride, copper(II) chloride, copper(II) sulfate, copper(II) hydroxide, copper(I) oxide, copper(II) oxide, manganese chloride, manganese nitrate, manganese carbonate , and nickel chloride.

The amount of the transition metal compound is usually 10 to 70 parts by mass, and may be 30 to 50 parts by mass, per 100 parts by mass of the support. Also, the amount of the transition metal compound is usually 1 to 20% by mass, and may be 1 to 10% by mass, based on the total mass of the granules. When the amount of the transition metal compound is within these ranges, it tends to be easy to obtain an oxygen scavenger having a suitable oxygen absorption capacity.

The oxygen absorbing composition may further contain a binder so that granules can be easily formed. Specific examples of binders include gum arabic, polyvinyl alcohol, sodium alginate, gelatin and cellulose. The amount of the binder is usually 0 to 30 parts by weight, and may be 10 to 20 parts by weight, per 100 parts by weight of the carrier.

The oxygen-absorbing composition may further contain other substances as necessary. Other substances include, for example, phenol compounds such as catechol, quinone compounds, and amine compounds. The amount of other substances is usually about 30 parts by mass or less with respect to 100 parts by mass of the carrier.

The particle diameter (maximum width) of the granules before adhesion of the inorganic fine particles is not particularly limited. Alternatively, it may be 1.5 mm or less. A smaller particle size or size of the granules tends to provide a higher oxygen absorption capacity.

The shape of the granules is not particularly limited, but may be cylindrical, for example. In the case of cylindrical granules, the bottom diameter may be 0.3 mm or more, 4.5 mm or less, or 1.8 mm or less. The height may be 0.3 mm or more, 10 mm or less, or 5 mm or less.

Inorganic fine particles contain an inorganic substance as a main component. The inorganic fine particles may be water-insoluble particles or slightly soluble particles. The inorganic microparticles may be hydrophilic (ie, hydrophilic inorganic microparticles). Inorganic fine particles usually contain 50% by mass or more of inorganic substances based on the total mass. The inorganic fine particles may consist essentially of inorganic substances. The inorganic substance is, for example, at least one selected from the group consisting of hydrophilic silicon dioxide, calcium silicate hydrate, magnesium oxide, magnesium hydroxide, calcium hydroxide, aluminum silicate, and charcoal (activated carbon). may The inorganic microparticles may be hydrophilic inorganic microparticles (eg, hydrophilic silicon dioxide particles).

The average particle diameter of the inorganic fine particles may be 150 μm or less. By setting the average particle diameter of the inorganic fine particles to be 150 μm or less, the oxygen absorbability of the oxygen absorber can be improved. Fine irregularities are usually formed on the surface of the granules, and inorganic fine particles having a small particle size easily enter the recesses on the surface of the granules. As a result, the surface area of the granules is greatly increased, which is considered to contribute to the improvement of the oxygen absorption capacity. From the same point of view, the average particle size of the inorganic fine particles may be 100 μm or less, or 50 μm or less. Although the lower limit of the average particle diameter is not particularly limited, it may be 0.1 μm or more, for example, because nano-sized fine particles are expensive and difficult to handle. The average particle size here is the value of the secondary particle size measured by a laser diffraction method.

The pore volume of the inorganic fine particles may be 0.5 mL/g or more. When the pore volume of the inorganic fine particles is 0.5 mL/g or more, the oxygen absorption capacity of the oxygen absorber can be improved. It is believed that inorganic fine particles having a large pore volume easily absorb the oxygen-absorbing composition near the surface of the granules. It is presumed that when the oxygen-absorbing composition (especially the oxygen-absorbing substance) is absorbed by the inorganic fine particles, the chances of the oxygen-absorbing substance coming into contact with oxygen in the environment increase, and as a result, the oxygen-absorbing capacity is improved. From a similar point of view, the pore volume of the inorganic fine particles may be 0.8 mL/g or more, or 1.2 mL/g or more. Although the upper limit of the pore volume is not particularly limited, it may be, for example, 10 mL/g or less. The pore volume here is a value measured by a nitrogen adsorption method or a mercury intrusion method. The pore volume measured by at least one of the nitrogen adsorption method and the mercury porosimetry method should be within the above numerical range.

The specific surface area of the inorganic fine particles may be 50-1000 m ² /g, or 100-400 m ² /g. When the specific surface area of the inorganic fine particles is within these numerical ranges, there is a tendency that the oxygen absorbability of the oxygen absorber can be further improved. The specific surface area here is a value measured by a nitrogen adsorption method or a water source injection method. The specific surface area measured by at least one of the nitrogen adsorption method and the water source injection method may be within the above numerical range.

The ability of the inorganic fine particles to easily absorb the oxygen-absorbing composition can contribute to the improvement of the oxygen absorbing ability of the oxygen absorber. The extent to which the inorganic fine particles absorb the oxygen-absorbing composition can be evaluated by the liquid absorption amount of the inorganic fine particles. The liquid absorption amount is measured by a method in which a liquid composition containing an oxygen-absorbing substance and a transition metal compound is used as a test liquid and is absorbed by the powder of inorganic fine particles. The test liquid for measuring the liquid absorption amount contains the oxygen-absorbing substance and the transition metal compound in the same mass ratio as the liquid oxygen-absorbing composition used for the production of the oxygen absorber. When the liquid absorption amount (the mass of the absorbed test liquid per 1 g of the inorganic fine particles) measured by this method is 2.0 g/g or more, there is a tendency that a high oxygen absorption capacity can be obtained. From the same point of view, the liquid absorption amount may be 2.5 g/g or more, or 3.0 g/g or more. Although the upper limit of the liquid absorption amount is not particularly limited, it may be, for example, 20 g/g or less.

The liquid absorption amount of inorganic fine particles can be measured by the following procedure.
(1) Glycerin, copper (II) sulfate and water are mixed in a mass ratio of 50:15:20 to prepare a test solution.
(2) The inorganic fine particles are kneaded with a spatula while dropping the test liquid little by little onto a predetermined amount of the inorganic fine particles. The amount (limit amount) of the test liquid dropped until the powdery inorganic microparticles form one lump while absorbing the test liquid is recorded. When the drop amount of the test liquid exceeds the critical amount of the inorganic fine particles, the inorganic fine particles cannot absorb the test liquid, and one lump collapses to form a slurry.
(3) Calculate the amount of absorbed liquid by the following formula.
Liquid absorption amount [g/g] = critical amount of test liquid [g] / mass of inorganic fine particles [g]

When the liquid absorption amount of the inorganic fine particles is Q and the average particle diameter of the inorganic fine particles is d, Q ² /d may be 0.3 [μm ⁻¹ ] or more. A correlation is recognized between the oxygen absorption capacity and the value of Q ² /d, and the oxygen absorption capacity tends to increase as the value of Q ² /d increases. From a similar point of view, Q ² /d may be 0.5 or more. Although the upper limit of Q ² /d is not particularly limited, it may be 10 or less, for example.

The inorganic fine particles having the average particle size, pore volume, specific surface area, and liquid absorption amount exemplified above can be produced by a well-known method, and can be obtained by appropriately selecting from commercially available products.

The amount of inorganic fine particles adhering to the surface of the granules (attachment amount) is 0.1 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more with respect to 100 parts by mass of the granules. , 2 parts by mass or more, or 3 parts by mass or more. When the amount of the inorganic fine particles is within these ranges, the appropriate oxygen absorption capacity of the oxygen scavenger is likely to be obtained. The upper limit of the amount of the inorganic fine particles adhering to the surface of the granules is not particularly limited. It may be less than or equal to parts by mass. Although individual inorganic fine particles not adhering to the granules may be contained in the oxygen absorber, the amount of individual inorganic fine particles not adhering is not included in the amount of adhesion.

The inorganic fine particles adhering to the surface of the granule cover the surface of the granule continuously or intermittently. The inorganic fine particles form a relatively thin layer, and the layer thickness is, for example, 1 mm or less, or 0.7 mm or less. When the surface of the composite particles is subjected to elemental analysis by energy dispersive X-ray analysis (EDX analysis), the fact that the layer of inorganic fine particles is thin indicates that the material (oxygen-absorbing substance, alkaline compound, or transition metal compound) constituting the granules is It can also be confirmed because the element contained in is detected. In general, in the case of the oxygen absorber according to the present embodiment, at least one element contained in the material constituting the granules is detected at a concentration of 0.05 atomic % or more, or 0.1 atomic % or more. can be

It should be noted that the oxygen absorber of the present embodiment is different from a tablet in which an outer shell portion is formed around an inner portion by tableting, for example. Since the outer shell formed by tableting necessarily has a certain thickness, the elements of the material constituting the inner portion are not substantially detected by EDX analysis.

[Oxygen absorber package]
An oxygen absorber package according to one embodiment can be mainly composed of the oxygen absorber according to the above embodiment and an air-permeable packaging material containing the oxygen absorber. The air-permeable wrapping material can be appropriately selected from those commonly used in the technical field. Specific examples of air-permeable packaging materials include bags made of a base material made of perforated plastic film, nonwoven fabric, microporous film, paper, or a combination thereof. This oxygen absorber package can be housed in, for example, various food packaging containers and used for the purpose of maintaining the freshness of food.

[Food packaging]
A food package according to one embodiment includes the above oxygen absorber package and a food packaging container in which the oxygen absorber package is enclosed. The food packaging container can be appropriately selected from those commonly used in the field of food packaging, and a sealable container is suitable. Food packaging containers include bags, deep drawn packages, tray packages, stretch packages and the like.

[Method for producing oxygen scavenger]
A method for producing an oxygen absorber according to one embodiment includes a powder-liquid mixing step of mixing a porous support and a liquid oxygen-absorbing composition to obtain a mixture, and granulating the mixture to obtain a granule. A granulation step and an attachment step of attaching inorganic fine particles to the surface of the granulated material to obtain composite particles are provided.

In the powder-liquid mixing step, for example, a powder containing at least a carrier and an alkaline compound and a liquid containing at least an oxygen-absorbing substance are mixed to obtain a mixture (powder-liquid mixture). Each component may be mixed at once or may be mixed several times for each component. The mixer is not particularly limited, and may be, for example, a container rotation type mixer such as a cylindrical type or a V type, or a fixed container type such as a ribbon type, horizontal screw type, paddle type, or planetary motion type. It may be a mixer.

In the granulation step, the obtained mixture is granulated to obtain granules containing the porous support and the liquid oxygen-absorbing composition. Granulation can be carried out using a granulator, for example, by extrusion granulation using a screen having predetermined apertures.

As the porous support and the alkaline compound, those having an average primary particle diameter of 200 nm or more of the particles constituting each are used. By intentionally using a porous carrier having a large average primary particle size and an alkaline compound in the production of the oxygen scavenger, the productivity of the oxygen scavenger can be improved. This is because adhesion of these particles to the powder-liquid mixing device and the granulating device is suppressed particularly in the powder-liquid mixing step and the granulating step, and as a result, continuous operation of the device becomes possible. From this point of view, the average primary particle diameter of the particles constituting the porous support and the particles constituting the alkaline compound may be 250 nm or more, 300 nm or more, or 350 nm or more. , 400 nm or more, or 500 nm or more. Although the upper limit of the average primary particle size is not particularly limited, it can be 1000 nm or less from the viewpoint that oxygen absorption performance tends to decrease when the primary particle size is too large. This upper limit may be exceeded depending on the type of particles forming the porous carrier. For example, activated carbon can have a primary particle size as large as 50 μm, and unlike other porous bodies and alkaline compounds, it generally does not form secondary particles as aggregates. The average primary particle size here is a value converted from the following formula using the specific surface area and density.
Average primary particle size [nm] = 6/(specific surface area [m ² /g] x density [g/cm ³ ]) x 1000

The specific surface area of the particles constituting the porous support and the particles constituting the alkaline compound is 16 m ² /g or less. By deliberately using a porous carrier having a small specific surface area and an alkaline compound in the production of the oxygen scavenger, the productivity of the oxygen scavenger can be improved. The specific surface area of the particles constituting the porous support and the particles constituting the alkaline compound may be 12 m ² /g or less. Although the lower limit of the specific surface area is not particularly limited, it can be 1 m ² /g or more from the viewpoint that the oxygen absorption performance is lowered when the specific surface area is too small. The specific surface area here is a value measured by a nitrogen adsorption method or a water source injection method. The specific surface area measured by at least one of the nitrogen adsorption method and the water source injection method may be within the above numerical range.

In the adhering step, the granules obtained in the granulating step are mixed with the inorganic fine particles. This makes it possible to obtain composite particles (particles constituting the oxygen absorber) by adhering the inorganic fine particles to the surface of the granules. For example, the inorganic fine particles can be adhered to the granules by mixing the granules and the inorganic fine particles and shaking the resulting mixture.

Other matters concerning the carrier, the oxygen-absorbing composition, the inorganic fine particles, etc. are as explained in the section on the oxygen scavenger.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

1. Production of Evaluation Samples Of the raw materials shown in Table 1, only calcium hydroxide was changed to those shown in Table 2, and mixed uniformly in a sealed state to obtain oxygen-absorbing compositions of Examples 1 to 4 and Comparative Examples 1 to 3. A mixture containing

The average primary particle size of the activated carbon was measured using a laser diffraction measuring device represented by Shimadzu Corporation's "laser diffraction particle size distribution measuring device SALD-2300", and the result was 47 μm. rice field.

The average primary particle size of calcium hydroxide was calculated by the following formula after measuring the specific surface area using a gas adsorption measuring device such as "Flowsorb III2310" manufactured by Shimadzu Corporation.
Average primary particle size [nm] = 6/(specific surface area [m ² /g] x density [g/cm ³ ]) x 1000

2. Evaluation of stickiness As a method for evaluating stickiness, a kneading test using a mortar was carried out, and the weight of the mixture adhering to the mortar after the test was evaluated. The details of the evaluation procedure are as follows.
(1) The weight of the mortar and pestle was measured.
(2) 5.0 g of each sample of Examples and Comparative Examples was weighed and put into a mortar.
(3) The sample in the mortar was kneaded with a pestle for 2 minutes at constant speed and force.
(4) After kneading, the mortar and pestle were traced with a finger with a constant force to remove the adhering sample.
(5) The weight of the mortar and pestle after removing the sample was measured.
(6) (Weight of (5)) - (Weight of (1)) was taken as the fixed amount of the sample.
The above (1) to (6) were repeated 5 times for each sample, and the average value of the adhered amount at that time was used as the evaluation value. Table 3 shows the results. It was confirmed that the adhered amount was small in the examples.

3. Evaluation of suitability for continuous operation of manufacturing equipment (powder-liquid mixer) Confirmed proper driving. Specifically, the powder agent and the liquid agent were simultaneously fed into the powder-liquid mixer at a constant rate, and the current value of the powder-liquid mixer was monitored for 30 minutes. The increase rate of the final current value (operating time: average value of current value for 29 to 30 minutes) to the initial current value (operating time: average value of current value for 1 to 2 minutes) at that time is "current value increase rate ” was evaluated. Table 4 shows the results. It was confirmed that the samples of Examples have good suitability for continuous operation in production facilities.

4. Production of oxygen scavenger 3 above. The granulated product of the example obtained in 1. and inorganic fine particles were placed in a V-type mixer and shaken. As the inorganic fine particles, hydrophilic porous silica (average particle size: 3.84 μm, liquid absorption amount: 4.05 g/g) was used. The inorganic fine particles were used in an amount of 5 parts by mass with respect to 100 parts by mass of the granules. As a result, composite particles (oxygen absorber) comprising the granules and the inorganic fine particles adhering to the surfaces of the granules were produced. The obtained composite particles were observed by SEM to have particle sizes substantially corresponding to the average primary particle sizes of the activated carbon and calcium hydroxide used as raw materials.

Claims (8)

a powder-liquid mixing step of mixing a porous support and a liquid oxygen-absorbing composition to obtain a mixture;
a granulation step of granulating the mixture to obtain granules;
an attaching step of attaching inorganic fine particles to the surface of the granulated material to obtain composite particles;
the oxygen-absorbing composition comprises an oxygen-absorbing substance and an alkaline compound;
The average primary particle diameter of the particles constituting the porous support is 200 nm or more, and the average primary particle diameter of the particles constituting the alkaline compound is 200 nm or more and 1000 nm or less ,
the alkaline compound comprises calcium hydroxide;
A method for producing an oxygen absorber, wherein the amount of the inorganic fine particles is 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the granules . 2. The production method according to claim 1, wherein the amount of said oxygen-absorbing substance is 20 to 30% by mass based on the total mass of said granules. 3. The production method according to claim 1, wherein the amount of said alkaline compound is 100 to 300 parts by mass with respect to 100 parts by mass of said support. Composite particles comprising granules containing a porous carrier and a liquid oxygen-absorbing composition, and inorganic fine particles adhering to the surface of the granules,
the oxygen-absorbing composition comprises an oxygen-absorbing substance and an alkaline compound;
The average primary particle diameter of the particles constituting the porous support is 200 nm or more, and the average primary particle diameter of the particles constituting the alkaline compound is 200 nm or more and 1000 nm or less ,
the alkaline compound comprises calcium hydroxide;
An oxygen absorber in which the amount of the inorganic fine particles is 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the granules. 5. The oxygen scavenger according to claim 4, wherein the amount of said oxygen-absorbing substance is 20 to 30% by mass based on the total mass of said granules. 6. The oxygen absorber according to claim 4 , wherein the amount of said alkaline compound is 100 to 300 parts by mass with respect to 100 parts by mass of said carrier. An oxygen absorber package comprising: the oxygen absorber according to any one of claims 4 to 6 ; and a breathable packaging material containing the oxygen absorber. A food package comprising: the oxygen absorber package according to claim 7 ; and a food packaging container enclosing the oxygen absorber package.