JPH02298343A - Manufacture of oxygen absorbent - Google Patents

Abstract

PURPOSE:To permit the manufacturing of a self-reactive oxygen absorbent excellent in quality on a constant basis by placing the powder consisting of iron powder and metal halide and the porous granulated substance impregnated with aq. metal halide soln. into a gas-permeable container. CONSTITUTION:After metal halide has been dissolved in water or other solvent, the water is made to evaporate to attach the metal halide firmly on the surface of iron powder (the resulting powder is referred to as component A). After placing porous granulated substance into a mixer, aq. metal halide soln. obtained from a predetermined amt. of the metal halide and water is sprinkled and a cycle of the mixing and standing is repeated a few times so as to prepare porous granulated substance (component B) uniformly impregnated with the aq. metal halide soln. The aforesaid components A and B are placed into a gas-permeable container formed of a gas-permeable substrate such as paper, nonwoven fabric, etc., to form an oxygen absorbent. The components A and B may or may not be contacted with each other immediately before the reception thereof into the container.

Description

[Detailed description of the invention] (a) Purpose of the invention [Field of industrial application] The present invention relates to an oxygen absorbent used for preserving processed foods, agricultural and marine products, metal products, precision parts, textile products, etc. It is widely used in various industries.

[Conventional technology]

One of the methods for maintaining the quality of processed foods, agricultural and marine products, metallurgical products, precision parts, textile products, etc. is to use oxygen absorbers (oxygen scavengers). In this method, the object is sealed and stored in a gas-barrier container, such as a bag or box made of non-breathable packaging material, together with an oxygen absorber wrapped in breathable packaging material, and the oxygen in the sealed container is removed. By absorbing oxygen with an oxygen absorbent and creating an oxygen-free (or low oxygen concentration) state, the object is intended to be protected from quality deterioration caused by oxygen.

Since this method appeared on the Japanese market in 1971,
It has rapidly become popular over the past 15 years due to its simplicity and high quality maintenance effect. Many types of oxygen absorbers have been proposed, including organic and inorganic ones, depending on the main agent that absorbs oxygen, but iron powder-based ones are the mainstream due to their superior functionality and economical efficiency. It is.

As an iron powder-based oxygen absorber, British Patent No. 553
, No. 991, a method has been proposed that uses active iron powder treated with hydrogen gas as a main ingredient and absorbs oxygen even in a dry state.

However, such active iron powder has a risk of ignition and is of little practical use.

Conventionally, all iron powder-based oxygen absorbents that have been practically used have stable iron powder as the main ingredient, and utilize the oxygen absorption reaction (i.e., the oxidation reaction of iron powder) as shown in the chemical formula below, for example. It contains water, metal halide, etc. as essential components.

2Fe(OH), 10% O, +H, 0-+2・F'e (
OH), 4Fe, O, ・3H,0 (here, X- represents a halogen ion, etc., which is a reaction accelerator). Depending on how certain water (H, O) is supplied to the reaction system, it is commonly known as self-reaction type (or self-reaction type).
It is roughly divided into two types: and water-dependent type.

A self-reactive oxygen absorbent contains water and immediately starts an oxygen absorption reaction when it comes into contact with air (strictly speaking, the #R element). This self-reactive type is characterized by its ability to quickly absorb oxygen even when the object to be preserved contains no moisture or has little moisture.

On the other hand, moisture-dependent types do not have moisture themselves, and after being sealed in a container with an object to be preserved (for example, food), they absorb oxygen using the small amount of moisture that evaporates from the object. This moisture-dependent type does not react immediately upon exposure to air, so it is characterized by very good workability during production.

The method of the present invention relates to self-reacting types of iron powder-based oxygen absorbents.

Conventional technology regarding self-reactive iron powder-based oxygen absorbers is proposed in West German Patent No. 869.042 (1953), in which a mixture of metals such as zinc and iron and activated carbon is mixed with ammonium chloride or potassium chloride solution. There is a method of absorbing oxygen from a gaseous body by moistening it, but it cannot be applied as is as a method for producing oxygen absorbents in small packages that are easy to handle.

Furthermore, in West German Patent No. 1.109.499 (1961), a dry material consisting of iron powder and activated carbon is moistened with a saturated potassium chloride solution, mixed thoroughly, and then filled into a sachet to create oxygen. A method has been proposed in which an absorbent is sealed in a can together with roasted coffee beans to completely absorb the oxygen inside the can. However, the method for manufacturing the oxygen absorbent proposed here has the disadvantage that the oxygen absorption reaction progresses during the powder mixing stage, resulting in a considerable loss of performance by the time it is filled into sachets. This method has the disadvantage that special methods such as inert gas replacement must be employed in order to achieve this.

In Japanese Patent Publication No. 57-31449, as a method for solving the above-mentioned problems in the production of self-reactive oxygen absorbers,
The three essential components of the oxygen absorber, iron powder, water, and metal halide, are divided into two parts: iron powder and a filler (B) impregnated with an aqueous solution of metal halide, and are brought into contact with each other before packaging. A method of filling the air-permeable packaging material in two stages and packaging the products together is shown. in this way,
Since the oxygen-absorbing functional components do not come into contact with each other before packaging, there is an advantage that the product can be manufactured without any deterioration in oxygen-absorbing performance. It also has the drawbacks of slow speed and large variations in performance.

[Problem to be solved by the invention]

The problems of the conventional iron powder-based self-reactive oxygen absorbent manufacturing method as described above can be summarized as follows.

(11) In the method of mixing the essential components for the oxygen absorption reaction and then filling the gas permeable packaging material, the oxygen absorption performance is significantly reduced.

(2) A high-quality oxygen absorbent cannot be obtained by dividing the essential components of the oxygen absorption reaction and filling them into an air-permeable packaging material without contacting them before packaging.

In addition, there are large variations in quality.

The inventors of the present invention have conducted extensive studies to solve these problems.

(B) Structure of the Invention [Means for Solving the Problems] The present inventors have conducted various studies and found that in the method for producing a self-reactive oxygen absorbent, a metal halide and water are combined into a metal halide aqueous solution. By adopting a method in which porous granules are impregnated as a powder, and they are stored in an air-permeable container with as little contact as possible with the powder consisting of iron powder and metal halide before storage. The present invention was completed by discovering that the above-mentioned problems can be solved and a high-performance oxygen absorbent can be stably produced.

That is, the present invention relates to a method for producing an oxygen absorbent, which is characterized in that the following two components are brought into contact with each other in an air-permeable container immediately before being stored, or are stored without being brought into contact with each other before being stored.

(A) Powder consisting of iron powder and metal halide (13)
The method of the present invention will be explained in more detail with reference to porous granules impregnated with an aqueous metal halide solution.

The iron powder used as the four components of O iron powder is manufactured using various methods such as reduced iron powder, atomized iron powder, electrolytic iron powder, and ground iron powder.
These may be used alone or in combination. In order to improve contact with oxygen, iron powder with an average particle size of 400 μF or more, preferably 200 μF or more is used, but iron powder that is too fine may cause dusting during manufacturing processes such as mixing and filling. The average particle size is preferably 60 μm or more, since this may result in poor fluidity.

Metal halides used together with iron powder as the four metal halides include sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium chloride, calcium chloride, magnesium chloride, and barium chloride. Powders of one or more kinds of alkali metal or alkaline earth metal halides shown in the following are preferably used.

The amount of the metal halide added is preferably 0.05 to 50 parts by weight, and particularly preferably 01 to 20 parts by weight, based on 100 parts by weight of iron powder, which is the main ingredient for oxygen absorption. If the amount of metal halide is less than the above lower limit value, the effect of improving oxygen absorption performance cannot be obtained, and if the amount is more than the upper limit value, the breathable draft component will be
Inconvenient things are more likely to occur, such as seeping into breathable packaging materials.

As the metal halide used for component (B), (A
) The same type of metal halide used in the component is used.

The amount of the metal halide constituting the component is preferably 1 to 100 parts by weight per 100 parts by weight of the porous granules.
Particularly preferred are 2 to 60 double parts. If the amount of halogenated gold powder is less than the upper limit, the oxygen absorption performance of the oxygen absorbent finally obtained by filling component (3) and (B) will be poor, and the amount will be greater than the upper limit) There is a risk of impairing the fluidity of the ingredients.

The proportion of gold halide blended into component (4) and component ()3 is 2 to 50 parts by weight in component (A), 98 to 50 parts by weight in component (13), and particularly 4 to 40 parts by weight in component W. weight part,
It is preferable to mix it with component (B) in an amount of 96 to 60 parts by weight.

○ The porous granules used for the porous granules (B) component are porous,
Any granular material with good water absorption can be used, but
BET surface area: 10m'/1 or more, water absorption rate: 10cm or more, particle size: 0.1-5'! % can be preferably used.

Examples of such porous granular materials include natural zeolite, synthetic zeolite, diatomaceous earth, perlite, activated alumina, silica gel, activated clay, magnesium silicate, sepiolite, various clay minerals, activated carbon, and other granular materials.

The upper limit of the amount of water used in component 0 water (8) is preferably below the saturated water absorption amount of the porous granules, and in the very vicinity of the saturated water absorption amount, water is exposed on the surface of the obtained water-containing granules. As a result, the fluidity of the granules deteriorates, so the saturated water absorption amount is 0.
More preferably, it is 95 times or less.

The lower limit of the amount of water is preferably 1 inch or more of the dry weight of the granules, and if the raw granules already contain 1% or more of water, the water content must be taken into consideration.

0 fA of component (A)* Component (A) is prepared by simply mixing iron powder and metal powder. After mixing with the powder, the water or solvent may be evaporated to make it adhere to the surface of the iron powder.

When metal halide is mixed with iron powder in the form of powder, it is preferably a fine powder with a particle size of 1 to 20 mm or less, particularly 20 mm or less.
It is preferable to have a particle size of 0μ or less.

0 Preparation of component (B) The method for preparing porous granules impregnated with an aqueous metal halide solution is not particularly limited (various methods can be used).

For example, after putting porous granules into a mixer, sprinkle a metal halide aqueous solution obtained from a predetermined amount of metal halide and water, and repeat mixing and standing several times to uniformly impregnate the aqueous solution. It is possible to obtain granulated material. It is also effective to divide the spraying of the aqueous solution and repeat the spraying and mixing two or more times to obtain uniform porous granules impregnated with water-soluble metal chlorides.

Note that it is also effective to use a component containing various auxiliary additives, including deodorants such as activated carbon, reaction regulators such as calcium hydroxide and magnesium hydroxide, and such auxiliary additive powders. It is added after producing porous granules impregnated with an aqueous metal halide solution.

O Breathable container The breathable container used in the method of the present invention refers to a pouch made of breathable packaging material or a small-capacity molded box-shaped container, etc. There is no particular limitation on the packaging material, and any packaging material can be used as long as it has air permeability.

Here, air permeability refers to air permeability that can be measured by, for example, the Gurley air permeability shown in JISP-8117, and the preferable one for the present invention is the Gurley air permeability = 0.1 to io
o, ooo seconds/1001d.

In addition, even if the packaging material itself cannot be measured for Gurley air permeability, it will be red (for example, even if the surface of the packaging material is covered with a substantially non-breathable layer, after the container is formed, the air permeability from the cross section of the adhesive surface will be A container configured to do so is also a breathable container that can be used in the method of the present invention.

Specific examples of breathable packaging materials include the following.

t.Things consisting of a breathable base material such as paper or nonwoven fabric, and a plastic film that has breathability and heat sealability.

As the paper or nonwoven fabric in the carrier structure, those commonly used as packaging materials are used.
For example, examples of paper include Japanese paper, kraft paper, pure white wrapping paper, pure white roll paper, water-resistant paper, oil-resistant paper, oil- and water-resistant paper, thin paper, etc., but are not limited to these. do not have. In addition, as a nonwoven fabric, as long as it has a higher melting point than a plastic film that has air permeability and heat-sealability, which will be described later, it can be used without being restricted by the raw material fiber or manufacturing method. polyester, polyamide, polypropylene, polyethylene,
Examples include acrylic, and manufacturing methods include dry method, wet method, spunbond method, needle punch method, etc.
Products manufactured by combining them can be used. In addition, microporous membranes made by forming micropores in films produced by various methods and commercially available are also used as paper or nonwoven fabrics in the present invention.

In addition, a plastic film that has breathability and heat-sealing properties constitutes the inner layer when packaged for an oxygen absorber, and is generally used as a sealant. It is preferable that the material has a softening point lower than that of the base material, and that it has air permeability through holes, and has a thickness of 10 μm or more and 500 μm or more.
The following are preferred.

Specific examples include polyethylene film, polypropylene film, ethylene vinyl acetate copolymer film, and ionomer film. There are no special conditions for the shape, number, etc. of the pores in a film with pores as through holes, but the pores are preferably 6 cm in diameter or less, preferably about 0.5 mm in diameter, and the number is preferably 1 cm.
2 to 300 pieces per 11, more preferably 2 to 100 pieces
Certain types are preferred for the present invention, and the size and type of pores can be selected depending on the desired oxygen removal rate.

Methods for laminating the breathable base material and breathable sealant include wet lamination, dry lamination,
Conventional film lamination methods such as hot melt lamination and thermal lamination can be applied. Furthermore, when laminating the air-permeable base material and the air-permeable sealant, it is also possible to apply a method in which a space layer is provided in the middle and the layers are laminated without bonding both layers together.

2. Above 1. A plastic film layer is added to the outside of the above structure, that is, (1) a plastic film layer, an air permeable base material such as paper or non-woven fabric, and an air permeable and heat-fusible film.

Here, the plastic film (0) has a softening point higher than the breathable and heat-adhesive film (2), such as polyethylene, polypropylene, nylon, polyethylene terephthalate, cellophane, polystyrene, and polyvinyl chloride. Single layer films and films made by laminating two or more of these films can be applied.■
The plastic film is made of ■ to provide breathability.
It is also possible to suitably use a sealant layer with penetrating pores as in the case of the sealant layer, and in this case, the cross section of the heat-sealing layer after the package is formed becomes the ventilation surface.

As for the method of laminating the plastic film layer and the paper or non-woven fabric layer (2), ordinary film lamination methods such as extrusion lamination, wet lamination, dry lamination, hot melt lamination, and thermal laminator 1 can be applied. Ru. In addition, the plastic layer of ■,
When laminating the paper or nonwoven fabric layer described in (2) above, it is also possible to apply a method in which a space layer is provided in the middle and laminated without bonding both layers.

3. Materials that are breathable and heat-sealable, such as polyolefin resin nonwoven fabric or paper mixed with its fibers.

Raw material polyolefin resins include polyethylene,
Examples of the manufacturing method include a dry method, a wet method, a spunbond method, a needle punch method, etc., and those manufactured by a combination of these methods can be used. Furthermore, films made by forming micropores by various methods and commercially available as microporous films can also be used as nonwoven fabrics.

As described above, the formation of a pouch for an oxygen absorber using the air-permeable packaging materials 1 to 3 is carried out by placing the heat-sealable side of the same or different type of air-permeable packaging materials exemplified in 1-5 on the inside. This is done by facing each other and heat sealing the peripheral edges.

Alternatively, use one of the breathable packaging materials exemplified in 1 to 3 on one side, and use a normal non-breathable laminated film such as polyethylene terephthalate/polyethylene Onita & Main, nylon/poly, ethylene, etc. on the other side in the same manner as above. By forming a pouch,
It is also possible to make an oxygen absorbent pouch having air permeability on only one side.

0 Storage method Component (A) and component (B) prepared as described above are stored separately without contact, filled and stored in a breathable container, and weighed separately when packaging. An oxygen absorbent is produced by filling and storing the container in a breathable container and sealing the container.

Here, the ratio of (Al component and (Bl component) is not particularly limited and is appropriately selected taking into consideration oxygen absorption rate, oxygen absorption capacity, manufacturing cost, etc. (3) Per 100 parts by weight of iron powder in the ingredients, (13
) The water content in the component is 1 to 200 parts by weight, especially 5 to 15 parts by weight.
It is preferable to use a ratio such that 0 parts by weight and the total amount of metal halide is 1 to 100 parts by weight, particularly 2 to 50 parts by weight.

When filling and storing in a breathable container, component (A) and component (J3) are filled and stored separately without contact, so that component (4) and component (Bl) are present in two separate stages within the container. As mentioned above, the method of filling the container is a known method, but a part of the filling pipe from the storage tank to the container is shared, and furthermore,
Dampers, stirring blades, etc. are installed, and immediately before the container is filled and stored, the components (A) that have not come into contact with each other)
Allowing the components to come into contact and mix is the preferred method to obtain uniformity of performance of the oxygen absorbent produced.

[For production]

In the production of oxygen absorbents consisting of iron powder, water, and metal halides, when the oxygen absorbent is stored in a container such as a sachet and can be used as is, three components: iron powder, water, and metal halides are used. be stored in a ventilated container without touching them at the same time, and weighed separately before storage.
As much as possible, the three parties should be stored without coming into contact with each other.
In addition, a self-reactive type of oxygen absorbent is produced by combining the metal halide and water into an aqueous solution, impregnating porous granules, and then mixing it with powder consisting of iron powder and metal halide to produce an oxygen absorbent. It has the effect of solving the following problems that conventional oxygen absorbers have had.

(1) Deterioration in quality due to poor dispersion caused by storing iron powder without contact with water and metal halides;
difficulty in manufacturing products of consistent quality;

(2) Deterioration in performance due to contact between iron powder, water, and metal halide in the presence of oxygen.

The above excellent effects can only be achieved by adding metal halide to iron powder.

〔Example〕

The present invention will be described in more detail below based on Examples, including Comparative Examples.

Example 1: 10 kg of reduced iron powder with an average particle size of 80 μm was mixed with 0.2 kg of salt powder with an average particle size of 150 μm using a V-type mixer.
The powder obtained by mixing for a minute was designated as component (A).

Separately, granular sepiolite (magnesium silicate mineral, calcined at 200°C) with a particle size of 0.5 to 3 mm was placed in a V-shaped mixer, and a saline solution containing 1.2 kg of common salt dissolved in 46 mm of water was added to the mixer. Injected, mixed for 15 minutes, left for 8 hours, mixed again for 15 minutes, left for 16 hours, mixed for another 15 minutes, left for 8 hours (62 hours in total from the beginning),
By mixing for 15 minutes, granules with good fluidity were obtained. The obtained powder was used as component (B).

(4) Weigh the component and (B) component by 1.5z each,
Breathable packaging paper made by laminating paper and perforated polyethylene (
They were separately placed into a 40x50% size pouch made with a Gurley air permeability of about 2,000 seconds/100 at, filled in two layers, and sealed.

Five identical products were manufactured.

The obtained oxygen absorbent was sealed in a gas barrier bag with 500 ec of air, left at 20°C, and the change in oxygen concentration in the system was tracked and analyzed.
Section 3.5, 68%, 3.2%, 2.9% (average 3.5%
, standard deviation: σn-1=0.47) Both were 0% after 16 hours. 'Comparative Example 1゜In the method for producing component (B) of Example 1, the amount of added salt powder was 1.4 hours, and the other conditions were the same as in Example 1.
The obtained granules were designated as (131 components).

Only the iron powder used in Example 1 was collected.

Using these (A) component and CB) component, the other conditions were exactly the same as in Example 1, and only five oxygen absorbers were used. (In Example 1, salt is contained in both the recovered and CB components, but in this example, salt is contained only in the (B) component.) The oxygen absorption performance of the obtained oxygen absorbent was evaluated in Example When measured using the same method as in 1., after 8 hours, ZOchi, 4.
5chi, 5.1chi, ZOchi, 6.8chi (average 5.5chi, standard deviation σn-1-1,46), and all were 0% after 16 hours.

The average value of the residual oxygen concentration after 8 hours was higher than the average value of Example 1, and the data had a large variation (standard deviation).

Example 2゜For 10 yu of reduced iron powder with an average particle size of 80μ, an average particle size of 15
Component (A) was obtained by mixing 0.2 kg of 0μ salt powder for 15 minutes using a V-type mixer.

Separately, granular diatomaceous earth (1°200
℃ flux calcined product) was placed in a V-type mixer, a saline solution prepared by dissolving 2.1 kg of common salt in 8.0 kg of water was poured into it, and heated in the same manner as in Example 1 to obtain a fluidity. Got good granules. The obtained powder was used as component (B).

Weigh 1.5 t each of component (A) and component (B),
Breathable packaging paper made by laminating paper and perforated polyethylene (
They were separately placed into a 40 x 50% size pouch made with a Gurley air permeability of about 2,000 seconds/100 m1, filled in two layers, and sealed.

Five identical products were manufactured.

The obtained oxygen absorbent was sealed in a gas barrier bag with air so o cc, left at 20°C, and a follow-up analysis of changes in the oxygen concentration in the system revealed that after 6 hours, the oxygen concentration decreased to 4.0°C.
%, 4.2%, 4.7%, 4.6 excellent, 5.0% (average 4
, 5%, standard deviation: σn-, =O, 4O) After 16 hours, all were Ochi.

Comparative Example 2 In the method for producing the CB) component of Example 2, the 6kg of common salt powder was 2.3 kg, and the other conditions were the same as in Example 2, and the obtained granules (diatom-based) were ) component.

Example 2. Only the iron powder used in the above was collected. Using these recovered portions and component (B), the rest was as in Example 2. It is exactly the same, only the oxygen absorber is different. (
Example 2. (In this example, salt is contained in both component (A) and component (t3), but in this example, salt is contained only in component (B).) The oxygen absorption performance of the obtained oxygen absorbent is shown in Example 2. When measured using the same method, 45% and 82% after 6 hours.
, 5.7%, 6.5%, and 70% (average: 64 cm, standard deviation: σn-, = 1.39), and after 16 hours, they were all 0%.

The average value of the residual oxygen concentration after 6 hours is a higher value than the average value of the actual sand flow side 2, and the data variation (standard deviation) is also large.

←→ Effects of the Invention The present invention can greatly contribute to various industries that regularly use products of excellent quality without degrading the quality of self-reactive oxygen absorbers.

Claims (1)

[Scope of Claims] 1. A method for producing an oxygen absorbent, which comprises placing the following two components in a breathable container either in contact with each other immediately before storage, or without contacting them before storage. (A) Powder consisting of iron powder and metal halide (B) Porous granules impregnated with an aqueous solution of metal halide