WO2016117528A1 - Packaged sodium chloride and storage method for sodium chloride - Google Patents

Abstract

The purpose of the present invention is to provide a storage technology for sodium chloride having excellent property stability, with which it is possible to inhibit the solidification of sodium chloride, even during long-term storage, without adding additives. By setting the purity of sodium chloride to at least 99.5 wt% and the average particle diameter to at least 150 μm, storing the sodium chloride in a moisture-proof container having a moisture permeability of less than 3 g/m²∙24h, and setting the relative humidity inside the moisture-proof container so as to be maintained at 55% or less, it is possible to prevent the sodium chloride from solidifying even during long-term storage and to increase the property stability of the sodium chloride.

Description

Sodium chloride in a container and storage method of sodium chloride

The present invention relates to sodium chloride in a container that suppresses solidification of sodium chloride. The present invention also relates to a method for storing sodium chloride for stably storing the sodium chloride by suppressing solidification.

Sodium chloride is used in a wide variety of fields such as pharmaceuticals, cosmetics, foods, etc., but high-purity sodium chloride has a drawback that it solidifies during storage and becomes a lump. Such solidification of sodium chloride is considered to be caused by cross-linking of microcrystals precipitated by repeated absorption and release of moisture on the crystal surface. In high-purity sodium chloride, the water vapor pressure of the saturated sodium chloride solution is strongly solidified by repeated dissolution and precipitation by raising and lowering the relative humidity (critical humidity: about 75%) parallel to the vapor pressure of the gas phase. In typical handling, it will solidify over time even if kept below the critical humidity.

Conventionally, various means and prescriptions have been proposed to prevent the solidification of sodium chloride. For example, Patent Document 1 discloses that high-temperature sodium chloride is sufficiently dried in advance and finely pulverized to an average particle size of 100 microns or less in a dry atmosphere of about 0.5 g in 1 kilogram of air, while maintaining the dry atmosphere. A method for preventing caking of fine salt is disclosed, wherein the ground salt is sealed in an aluminum foil packaging bag. In this technique, the solidified sodium chloride, which is easy to solidify, is kept dry to the limit, and is pulverized in about 0.5 g of dry air in 1 kg of air, and stored in a moisture-proof bag using aluminum foil. Prevents solidification during storage. However, in the method of Patent Document 1, since the dry air must be pulverized, filled and sealed while strictly controlling the dry air to be about 0.5 g per kilogram, the production cost of sodium chloride is increased, and the sodium chloride is slightly reduced. Since the pulverization process is essential, the production process tends to be complicated. Further, even when salt with a water content of 0.1% is cooled in a low humidity atmosphere of about 1 to 2 g in 1 kg of dry air as described in Patent Document 1, the salt is substantially dried with dry air. Unless done, solidification cannot be prevented. In addition, Patent Document 1 does not clarify the relationship between the amount of water retained by sodium chloride after drying, the humidity in the package during storage, and the solidification of sodium chloride. Is disclosed that it does not solidify if it is pulverized and filled in as dry a state as possible.

Patent Document 2 discloses a method for suppressing solidification during storage by providing a heating means for stored sodium chloride. In the technique of Patent Document 2, moisture absorption of salt particles is caused by dew condensation when the temperature of the salt drops below the dew point temperature of the outside air and deliquescence when the salt particles are placed under conditions where the relative humidity exceeds 75%. The purpose is to suppress the phenomenon, and it has been found that the two moisture absorption phenomena can be prevented by increasing the temperature of sodium chloride. However, even the method of Patent Document 2 does not strictly control the amount of water held by sodium chloride, and the amount of solidification is substantially suppressed to some extent. Further, the relationship between the humidity in the package that is also affected by the moisture contained in sodium chloride and the solidification of sodium chloride has not been clarified.

Further, Patent Document 3 discloses that solidification can be suppressed by absorbing moisture in salt using dry kraft paper. However, in the method of Patent Document 3, there is a cost for drying the kraft paper bag, and it is necessary to directly fill the kraft paper with salt, so there is no problem for food use, but it is not preferable for pharmaceutical use. In addition, bags made of hygroscopic materials such as kraft paper, like silica gel, may be released in reverse to moisture adsorption depending on the temperature and humidity of the storage environment, so sodium chloride is re-solidified due to environmental changes. Sometimes

On the other hand, as a method of adding additives to suppress solidification of sodium chloride, a method of adding water-soluble cellulose esters (Patent Document 4), a method of adding disodium hydrogen phosphate or magnesium carbonate (Patent Document 5) ) A method of adding 5 to 500 ppm of sodium alginate (Patent Document 6) has been proposed. However, the method of blending these additives cannot be applied in the pharmaceutical field where high-purity sodium chloride is required, and has a drawback that the field of application of sodium chloride is limited.

JP-A-5-345610 JP-A-63-98367 JP-A-7-149387 JP-A-4-45836 JP-A-6-24738 JP-A-2-208219

For example, it is common knowledge that sodium chloride for pharmaceutical use has high purity and is easy to solidify. However, it is possible to provide sodium chloride as a pharmaceutical raw material that does not solidify for a long period of time without mixing of additives and the like. If possible, formulation operations such as weighing, blending, and mixing can be facilitated.

Also, in the field of powder dialysis agents, sodium chloride may be used as a simple preparation, and the sodium chloride single preparation is dissolved in a dialysis facility or the like that prepares the dialysis agent, and is solidified. If the above occurs, the dissolution operation becomes complicated and difficult to handle, and it becomes a defective product as a pharmaceutical preparation. Therefore, the development of sodium chloride that does not solidify even after long-term storage is strongly demanded in pharmaceutical applications including powder dialysis agents. At the same time, in the above-mentioned applications, the addition of a dispersant or an antioxidant that contaminates the contents does not simply prevent the solidification of sodium chloride. Is required to maintain.

Therefore, an object of the present invention is to provide sodium chloride storage technology that can suppress solidification of sodium chloride and is excellent in property stability even if stored for a long period of time without blending additives.

The present inventor conducted intensive studies to solve the above-mentioned problems. As a result, the purity of sodium chloride was set to 99.5% by weight or more, the average particle diameter was set to 150 μm or more, and the sodium chloride was subjected to moisture permeability of 3 g / m. Housed in a moisture-proof container of less than ² · 24h, and maintaining the relative humidity in the moisture-proof container at 55% or less, it is possible to prevent solidification of sodium chloride even when stored for a long period of time, and to stabilize the properties of sodium chloride It was found that the performance is improved. The present invention has been completed by further studies based on such knowledge.

That is, this invention provides the preservation | save method of the sodium chloride in a container of the aspect hung up below, and sodium chloride.
Item 1. Sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity in the moisture-proof container is 55% or less. Sodium chloride in a container, which is maintained and free from solidification of sodium chloride.
Item 2. Item 2. The sodium chloride in a container according to Item 1, wherein the sodium chloride is not in direct contact with the hygroscopic material contained in the moisture-proof container.
Item 3. Item 3. The sodium chloride in a container according to Item 1 or 2, wherein the relative humidity in the moisture-proof container is maintained at 50% or less.
Item 4. Item 4. The sodium chloride in a container according to any one of Items 1 to 3, wherein the average particle size of the sodium chloride is 150 to 700 μm.
Item 5. Item 5. The sodium chloride in a container according to any one of Items 1 to 4, wherein 0.1 kg to 1 t of sodium chloride is contained in a moisture-proof container.
Item 6. Item 6. The sodium chloride in a container according to any one of Items 1 to 5, wherein the water content of the sodium chloride is 0.002% by weight or less.
Item 7. Item 7. The sodium chloride in a container according to any one of Items 1 to 6, wherein the moisture permeability of the moisture-proof container is 0.5 g / m ² · 24 h or less.
Item 8. Item 8. The sodium chloride in a container according to any one of Items 1 to 7, wherein the moisture-proof container is a polyolefin moisture-proof container having a moisture-absorbing layer made of polyolefin containing a hygroscopic inorganic material.
Item 9. Item 9. The sodium chloride in a container according to Item 8, wherein the hygroscopic inorganic material is magnesium sulfate anhydride and / or zeolite.
Item 10. Item 10. The polyolefin moisture-proof container is formed of a laminate in which a resin layer having no additive is laminated on both surfaces of a moisture-absorbing layer made of polyolefin kneaded with a hygroscopic inorganic material. Sodium chloride in a container.
Item 11. Item 11. The sodium chloride in a container according to Item 10, wherein the laminate is a film or a sheet.
Item 12. Item 12. The sodium chloride in a container according to any one of Items 8 to 11, wherein the hygroscopic layer does not substantially contain additives other than the hygroscopic material.
Item 13. Item 13. The sodium chloride in a container according to any one of Items 1 to 12, wherein the purity of the sodium chloride is 99.9% by weight or more.
Item 14. Item 14. The sodium chloride in a container according to any one of Items 1 to 13, wherein 0.1 to 50 kg of sodium chloride is contained in the container.
Item 15. Item 15. The sodium chloride in a container according to any one of Items 1 to 14, which is used as a raw material for a powder dialysis agent.
Item 16. Sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity in the moisture-proof container is maintained at 55% or less. A method for preserving sodium chloride, characterized in that
Item 17. Item 17. The method for preserving sodium chloride according to Item 16, wherein the sodium chloride is not in direct contact with a hygroscopic material contained as a constituent material of the moisture-proof container.
Item 18. Item 18. The method for preserving sodium chloride according to Item 16 or 17, wherein the relative humidity in the container is maintained at 50% or less.
Item 19. Item 19. The method for preserving sodium chloride according to any one of Items 16 to 18, wherein the sodium chloride has an average particle size of 150 to 700 μm.
Item 20. Item 20. The method for preserving sodium chloride according to any one of Items 16 to 19, wherein 0.1 kg to 1 t of sodium chloride is contained in a container.
Item 21. Item 21. The method for preserving sodium chloride according to any one of Items 16 to 20, wherein the product temperature during filling and storage is maintained at 4 ° C. or higher and 50 ° C. or lower.
Item 22. Item 22. The method for preserving sodium chloride according to any one of Items 16 to 21, wherein the water content of the sodium chloride is 0.002% by weight or less.
Item 23. Item 23. The method for preserving sodium chloride according to any one of Items 16 to 22, wherein the moisture permeability of the moisture-proof container is 0.5 g / m ² · 24 h or less.
Item 24. Item 24. The method for preserving sodium chloride according to any one of Items 16 to 23, wherein the moisture-proof container is a polyolefin moisture-proof container having a moisture-absorbing layer made of polyolefin containing a hygroscopic inorganic material.
Item 25. Item 25. The method for preserving sodium chloride according to Item 24, wherein the hygroscopic inorganic material is magnesium sulfate anhydride and / or zeolite.
Item 26. Item 26. The polyolefin moisture-proof container is formed of a laminate in which a resin layer having no additive is laminated on both surfaces of a moisture-absorbing layer made of polyolefin kneaded with a hygroscopic inorganic material. How to store sodium chloride.
Item 27. Item 27. The method for preserving sodium chloride according to Item 26, wherein the laminate is in the form of a film or a sheet.
Item 28. Item 28. The method for preserving sodium chloride according to any one of Items 24 to 27, wherein the hygroscopic layer is substantially free of additives other than the hygroscopic material.
Item 29. Item 29. The method for preserving sodium chloride according to any one of Items 16 to 28, wherein the purity of the sodium chloride is 99.9% by weight or more.
Item 30. Item 30. The method for preserving sodium chloride in a container according to any one of Items 16 to 29, wherein 0.1 to 50 kg of sodium chloride is contained in a moisture-proof container.
Item 31. Item 31. The method for storing sodium chloride according to any one of Items 16 to 30, which is a method for storing sodium chloride used as a raw material for a powder dialysis agent.

According to the present invention, sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is accommodated in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity in the moisture-proof container is 55%. By the simple method of maintaining the following, the property stability of high-purity sodium chloride can be increased, and solidification of sodium chloride can be prevented even after long-term storage. In the present specification, “property stability” means a property of maintaining a state in which sodium chloride is not solidified, and that sodium chloride is not solidified even when stored for a long period of time. Say.

In addition, according to the present invention, the sodium chloride does not directly contact the additive and the hygroscopic material (desiccant, dry material) contained as a constituent material of the moisture-proof container, and the property stability of high-purity sodium chloride is improved. Sodium chloride utilizing the present invention is a simple preparation (single component preparation consisting of sodium chloride) used as a pharmaceutical raw material for which high-purity sodium chloride is required, especially for powder dialysis. Can be suitably used.

In Test Example 1, sodium chloride is accommodated in an additive-free polyethylene inner bag, the exterior is accommodated in an aluminum foil laminated bag, and the relative humidity in the moisture-proof container is measured over time. is there. In Test Example 1, sodium chloride is stored in a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material is kneaded, and the exterior is stored in an aluminum foil laminated bag. The relative humidity in the moisture-proof container is set as follows. It is a figure which shows the result measured with time. In Test Example 2, sodium chloride is accommodated in an additive-free polyethylene inner bag, the exterior is accommodated in an aluminum foil laminate bag, and the relative humidity in the moisture-proof container is measured over time. is there. In Test Example 2, sodium chloride is contained in a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material is kneaded, and the exterior is contained in an aluminum foil laminated bag. The relative humidity in the moisture-proof container is determined as follows. It is a figure which shows the result measured with time. In Test Example 3, sodium chloride is accommodated in an additive-free polyethylene inner bag, the exterior is accommodated in an aluminum foil laminate bag, and the relative humidity in the moisture-proof container is measured over time. is there. In Test Example 3, sodium chloride is contained in a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material is kneaded, and the exterior is contained in an aluminum foil laminated bag. The relative humidity in the moisture-proof container is set as follows. It is a figure which shows the result measured with time. In Test Example 4, sodium chloride was accommodated in an additive-free polyethylene inner bag, the exterior was accommodated in a flexible container bag, and the relative humidity and temperature in this non-moisture-proof container were measured over time. FIG. In Test Example 4, sodium chloride was housed in a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material was kneaded, and the exterior was housed in a flexible container bag. The relative humidity and temperature in this moisture-proof container It is a figure which shows the result of having measured this over time. In Test Example 5, sodium chloride is contained in an additive-free polyethylene inner bag or a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material is kneaded, and the exterior is accommodated in an aluminum foil laminated bag. It is a figure which shows the result of having measured the relative humidity in this moisture-proof container with time. In Test Example 6, sodium chloride was accommodated in an additive-free polyethylene inner bag or a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material was kneaded, and the exterior was accommodated in an aluminum foil laminated bag. It is a figure which shows the result of having measured the relative humidity in a moisture-proof container with time.

1. Sodium Chloride in a Container The sodium chloride in a container of the present invention is a sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h. The relative humidity in the moisture-proof container is maintained at 55% or less, and there is no solidification of sodium chloride. Hereinafter, the sodium chloride contained in the container of the present invention will be described in detail.

<Sodium chloride>
The sodium chloride used in the present invention has a purity of 99.5% by weight or more and an average particle size of 150 μm or more. In this way, high-purity sodium chloride with a predetermined average particle diameter is adopted and stored in a moisture-proof container with a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity is maintained at 55% or less. It is possible to suppress the solidification of sodium chloride.

In the present invention, the purity of sodium chloride is the ratio of sodium chloride contained in solid sodium chloride, and is the ratio of sodium chloride to the sum of sodium chloride and components other than sodium chloride (inorganic, organic, etc.). is there. In the present invention, the purity of sodium chloride is not particularly limited as long as it is 99.5% by weight or more, but from the viewpoint of using sodium chloride mainly for pharmaceutical applications, it is preferably 99.8% by weight. As mentioned above, More preferably, 99.9 weight% or more is mentioned.

The sodium chloride used in the present invention is not particularly limited as long as the average particle diameter is 150 μm or more, and examples thereof include about 150 μm to 2000 μm. The average particle diameter of sodium chloride is preferably more than 150 μm, more preferably 160 μm or more, still more preferably 200 to 700 μm, and most preferably 200 to 500 μm from the viewpoint of further improving the solidification preventing effect of sodium chloride. . In this specification, the average particle diameter of sodium chloride refers to a value determined by an automatic dry sonic sieving measuring instrument.

Further, regarding the water content of sodium chloride used in the present invention, the sodium chloride satisfies the above purity and the average particle diameter, and within a range in which the relative humidity in the container to be stored is maintained at 55% or less. Although set, from the viewpoint of further improving the solidification preventing effect of sodium chloride, it is usually 0.002% by weight or less, particularly preferably 0.001% by weight or less. Here, the water content of sodium chloride is measured as a loss on drying. According to the measurement conditions (1 g, 105 ° C., 2 hours) of the loss on drying of “sodium chloride” described in the 16th revision Japanese Pharmacopoeia. It is the value obtained according to this.

The method of satisfying the above-mentioned ranges for the purity, average particle size and water content of sodium chloride is known, and the sodium chloride used in the present invention has the purity, average particle size and water content within the above-mentioned ranges according to the known methods. Adjust it.

The sodium chloride used in the present invention may be used in any field of pharmaceuticals, foods, cosmetics, etc., but in the present invention, high-purity sodium chloride is used. It is particularly suitable as a pharmaceutical raw material. In particular, sodium chloride used as a raw material for powder dialysis agents, particularly sodium chloride simple preparations (single component preparations consisting of sodium chloride) used for powder dialysis agents, are used in large quantities. Highly accurate weighing is required and solidification prevention is strongly demanded, and it is particularly suitable as an application target of the sodium chloride contained in the container of the present invention.

In the present invention, “no solidification of sodium chloride” means that the high hygroscopic ability of sodium chloride itself and its equilibrium humidity are maintained by adjusting the purity and average particle diameter of sodium chloride to the specific conditions described above. This can be achieved by utilizing the capacity and storing it in a moisture-proof container described later and maintaining the relative humidity at 55% or less. In order to reduce the relative humidity in the moisture-proof container to 55% or less, it can be achieved by a relatively simple means of adjusting the temperature and humidity atmosphere when filling sodium chloride that has been dried to a normal degree. As long as the moisture resistance of the container is maintained, the relative humidity in the container is maintained at 55% or less. And the relative humidity in a container can be maintained by the hygroscopic action of sodium chloride itself, and even if sodium chloride is not in direct contact with the hygroscopic material, an environment in which sodium chloride does not solidify is stably created. Thus, the sodium chloride of the present invention can be prevented from solidifying by maintaining the relative humidity at 55% or less for a long period of time from sealing to opening.

<Container>
In the present invention, a moisture-proof container having a moisture permeability of less than 3.0 g / m ² · 24 h is used. The moisture permeability of the moisture-proof container is preferably 0.5 g / m ² · 24 h or less, more preferably 0.3 g / m ² · 24 h or less, more preferably 0.3 g / m ² · 24 h or less from the viewpoint of more effectively preventing the solidification of sodium chloride. Preferably, 0.1 g / m ² · 24 h or less is used. In the present invention, if two or more containers are used in multiple layers, the entire container only needs to satisfy the moisture permeability. In this specification, the moisture permeability is a value measured according to a method defined in JIS 0208-1976 “Moisture permeability test method for moisture-proof packaging material (cup method)”.

The moisture-proof container used in the present invention is not particularly limited as long as it has the above-mentioned moisture permeability, and examples thereof include a film container, a metal container such as stainless steel, a glass container, and a plastic bottle container. It is done. Among these containers, a film container is preferable from the viewpoint of easy handling.

As the moisture-proof container used in the present invention, specifically, a container that traps moisture from entering the outside of the container by a hygroscopic material such as a hygroscopic inorganic material (hereinafter referred to as “water vapor trapping container”). In some cases, a container that prevents moisture entering from the outside of the container by using a material such as glass or metal (hereinafter also referred to as a “water vapor barrier container”), and these are multi-layered Can be used in combination.

Specific examples of the water vapor trapping container include a resin container including a hygroscopic layer made of a resin containing a hygroscopic inorganic material. The hygroscopic layer can be formed of, for example, a resin kneaded with a hygroscopic inorganic material. Although it does not restrict | limit especially as resin used for formation of a moisture absorption layer, For example, polyolefin, such as polyethylene and a polypropylene, is mentioned. The resin used in the moisture absorption layer may be one kind alone, or a combination of two or more kinds. Further, the hygroscopic inorganic material used for forming the hygroscopic layer is not particularly limited, and examples thereof include magnesium sulfate anhydride and zeolite. The hygroscopic inorganic material used in the hygroscopic layer may be one kind alone or a combination of two or more kinds. The hygroscopic layer is preferably a polyolefin kneaded with a hygroscopic inorganic material, and more preferably a polyethylene kneaded with a hygroscopic inorganic material.

The hygroscopic layer is prepared by kneading a hygroscopic inorganic material into a heat-melted resin. Normally, when kneading the hygroscopic inorganic material into the resin, a dispersant or an antioxidant is added. The agent is being used. However, as described below, when a hygroscopic inorganic material is kneaded with a heat-melted resin, additives such as a dispersant and an antioxidant are essential. The hygroscopic layer contained has a problem of sodium chloride contamination due to bleedout of the additive.

In the prior art, without the addition of additives such as dispersants and antioxidants, the hygroscopic inorganic material cannot be uniformly dispersed in the resin, resulting in a decrease in moldability, film form, sheet form, etc. When it is molded into a molded body, fish eyes and the like resulting from aggregated grains are generated as a typical example of poor dispersion, and the appearance of the molded body is impaired, and at the same time, the moisture absorption function itself is affected. Furthermore, when a hygroscopic inorganic material is kneaded into a thermoplastic resin with a twin-screw extruder without blending these additives, a lump called an eye attaches to the die and the continuity of strand molding is poor. Often becomes. However, additives such as dispersants and antioxidants are likely to bleed out from the molded product and migrate (penetrate) into the sodium chloride content, discoloration on the appearance of sodium chloride, generation and dispersion of water insolubles. It has been a problem to cause contamination of chemicals and antioxidants. In particular, the problem due to the bleedout of such additives becomes more noticeable as the storage period becomes longer. Even a simple inorganic substance such as sodium chloride is contaminated by the additive when stored in a polyethylene film package to which additives such as a dispersant and an antioxidant are added. Assuming that sodium chloride contaminated with additives is dissolved and filtered before use, insoluble materials are generated when it is dissolved, the filtration speed is significantly reduced, and the filter filter life is shortened. I will let you. In particular, contamination with such additives causes serious problems for contents that require a high degree of purity (for example, pharmaceutical raw materials, particularly sodium chloride used as a component of infusion solutions and dialysis solutions). .

Therefore, the moisture-absorbing layer contained in the water vapor trapping container does not substantially contain additives such as dispersants, antioxidants, foaming agents, lubricants, and colorants (additives other than hygroscopic inorganic materials). It is desirable. Thus, the moisture absorption layer which does not substantially contain an additive other than the hygroscopic inorganic material can prevent the additive from bleeding out. Here, “substantially containing no additive other than the hygroscopic inorganic material” means that the additive is not contained or the content is such that the original function of the additive cannot be exhibited. Specifically, in the hygroscopic layer, the total content of additives other than the hygroscopic inorganic material is 0.04% by weight or less, preferably 0.01% by weight or less, more preferably 0% by weight. Means.

The moisture absorption layer substantially free of additives other than the hygroscopic inorganic material is a kneaded product of polyolefin and magnesium sulfate anhydride, and does not substantially contain additives other than magnesium sulfate anhydride, In addition, it can be molded using a polyolefin composition having a moisture content of 0.1% by weight or less (hereinafter sometimes referred to as “non-added polyolefin composition”). Details of the additive-free polyolefin composition will be described later.

The water vapor trapping container may be formed of the hygroscopic layer alone, but is preferably formed of a laminated body in which the hygroscopic layer and other layers are laminated. In the water vapor trapping container, trapping the water vapor to be transmitted from the outside of the container is important for preventing the solidification of sodium chloride. Therefore, the moisture absorbing layer is laminated with another resin layer in the water vapor trapping container. It is preferable that the container is disposed at a position other than the innermost surface of the container. As a specific embodiment of the water vapor trapping container, a container formed of a laminate in which a resin layer having no additive is laminated on at least a surface of the moisture absorbing layer disposed on the inner surface of the container; preferably both surfaces of the moisture absorbing layer And a container formed of a laminate in which a resin layer having no additive is laminated. Such a moisture-proof resin container can be formed into a bag-like container, for example, when the laminate is molded into a film, and when the laminate is molded by blow molding It can be a bottle-shaped container. The resin used in the resin layer is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon. Among these resins, polyolefin, particularly polyethylene, is suitable as a resin used for the resin layer because it has heat sealability and can be easily sealed in addition to being easily molded.

Specific examples of the water vapor barrier container include glass containers; metal containers such as stainless steel and aluminum; and resin containers including a barrier layer having a water vapor barrier function.

The barrier layer is not particularly limited as long as it has a barrier function against water vapor, and examples thereof include metal foils such as aluminum foil; vapor deposition films such as aluminum oxide and silica.

As a specific embodiment of the resin container including the barrier layer, a container formed of a laminate in which a resin layer is laminated on at least the inner surface of the barrier layer, preferably on both surfaces of the barrier layer Examples include a container formed of a laminate in which resin layers are laminated. The resin used in the resin layer is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon. Moreover, it is preferable that the additive is not contained in the resin layer distribute | arranged to the surface distribute | arranged to the container inner surface side of the said barrier layer among the said resin layers.

As a preferable example of the resin container including the barrier layer, a resin layer is laminated on both surfaces of the barrier layer, and the resin layer on the surface located inside the container is made of polyolefin and located outside the container. Examples thereof include a container formed of a laminate in which the resin layer on the surface is made of polyester or polyamide. Such a moisture-proof resin container can be formed into a bag-like container when the laminate is molded into a film, and is bottle-shaped when the laminate is molded by blow molding. Can be a container. In addition, a resin container including such a barrier layer is provided with heat sealability by the resin layer disposed on the inside, water vapor barrier property by the barrier layer, strength and durability by the resin layer disposed on the outside, and sealed. Properties, water vapor barrier properties, strength, durability and the like can be provided in a well-balanced manner.

The moisture-proof container used in the present invention may be formed of a laminate in which the moisture absorption layer and the barrier layer are laminated.

Among the moisture-proof containers used in the present invention, from the viewpoint of easy handling and the like, a resin container including a moisture-absorbing layer made of a resin containing a hygroscopic inorganic material, and a barrier layer having a water vapor barrier function are preferable. In the case of a large-capacity packaging container, a resin container including a hygroscopic layer is more preferable.

The shape of the moisture-proof container used in the present invention may be any of a bag shape, a bottle shape, a container shape, and the like, and may be appropriately set according to the amount of sodium chloride to be filled.

In the present invention, two or more containers may be used in multiple layers. For example, a resin container including the moisture absorption layer may be used as the inner bag, and a resin container including the barrier layer may be used as the outer bag. In addition, when two or more containers are used in multiple layers, it is sufficient that the entire container to be used has a moistureproof property capable of maintaining the internal relative humidity at 55% or less when sealed, for example, two or more containers. A combination of containers having moisture resistance may be used, or a combination of a container having moisture resistance and a container having no moisture resistance may be used. Of course, the container as a whole may be a combination of two or more layers in which moisture resistance cannot be obtained alone, provided that the moisture permeability described above is provided.

In the present invention, when filling sodium chloride of about 150 kg to 1 t, a so-called flexible container bag can be used. When a flexible container bag is used, a film-like moisture-proof container, preferably a film-like water vapor trapping container, may be used as the inner bag and / or the outer bag of the flexible container bag.

[No-added polyolefin composition suitably used in forming the moisture-absorbing layer]
Below, the additive-free polyolefin composition mentioned above is explained in full detail.

The additive-free polyolefin composition is a kneaded product of polyolefin and magnesium sulfate anhydride, does not substantially contain additives other than magnesium sulfate anhydride, and has a water content of 0.1% by weight or less. It is characterized by. Thus, among the hygroscopic inorganic fillers, magnesium sulfate anhydride is selected, and this is kneaded to the polyolefin without substantially adding an additive other than magnesium sulfate anhydride, and the water content is 0.1% by weight or less. By doing so, an additive-free polyolefin composition having good dispersibility of magnesium sulfate anhydride and excellent moldability can be obtained. And it becomes possible by using the said additive-free polyolefin composition to form the moisture absorption layer which does not contain additives other than a hygroscopic inorganic material substantially.

The type of polyolefin used in the additive-free polyolefin composition is not particularly limited, and examples thereof include polyethylene, polypropylene, and polybutylene. Among these polyolefins, polyethylene is preferably used from the viewpoints of relatively non-addition as a resin, moldability, dispersibility of magnesium sulfate anhydride, and the like. The polyethylene may be any of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), etc., but moldability, dispersibility of magnesium sulfate anhydride, etc. From this point of view, low density polyethylene is preferable. In the additive-free polyolefin composition, the polyolefin content is, for example, 40 to 95% by weight, preferably 50 to 80% by weight, and more preferably 60 to 80% by weight.

The additive-free polyolefin composition contains magnesium sulfate anhydride as a hygroscopic inorganic material. The average particle diameter of magnesium sulfate anhydride is not particularly limited, but from the viewpoint of dispersibility with respect to polyolefin, it is preferably 1 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 1 to 10 μm. Here, the average particle diameter of magnesium sulfate anhydride is a cumulative 50% diameter obtained from a weight cumulative particle size distribution measured by a laser diffraction / scattering particle diameter distribution measuring apparatus. In order to satisfy the moisture content described later in the additive-free polyolefin composition, the moisture content of the magnesium sulfate anhydride itself kneaded as a raw material is preferably small, particularly 2 wt% or less, more preferably 1 wt% or less. It is preferable. The magnesium sulfate anhydride kneaded as a raw material in the additive-free polyolefin composition is usually such that the magnesium sulfate crystals (7 hydrate) are dried and calcined, and then the above-mentioned average particle size is obtained using a pulverizer. It can be obtained by grinding. By calcination of magnesium sulfate crystals (7 hydrate) at 200 ° C. or higher, preferably 300 to 700 ° C., a magnesium sulfate anhydride having a water content of about 1% by weight or less can usually be obtained. Moreover, since the magnesium sulfate anhydride obtained after firing is easy to absorb moisture, it is desirable that the grinding after firing is performed in the presence of dry air having an absolute humidity of about 10 g / kg DA or less. By performing firing and pulverization in this manner, it is possible to obtain magnesium sulfate anhydride that is easily dispersed in polyolefin. In the additive-free polyolefin composition, the content of magnesium sulfate anhydride may be appropriately set according to the use of the polyolefin composition, the moisture absorption characteristics to be provided, etc., for example, 5 to 60% by weight, preferably 20%. -50% by weight, more preferably 20-40% by weight.

The additive-free polyolefin composition is a kneaded product of polyolefin and magnesium sulfate anhydride, and is produced by kneading magnesium sulfate anhydride into molten polyolefin so as to satisfy the above-described moisture content. However, polyolefin and magnesium sulfate anhydride each have moisture, and simply kneading polyolefin and magnesium sulfate anhydride cannot satisfy the moisture content described above, and the dispersibility of magnesium sulfate anhydride is low. Only a polyolefin composition having poor moldability can be obtained. Therefore, by kneading polyolefin and magnesium sulfate anhydride under reduced pressure conditions, it is possible to remove moisture during kneading and obtain an additive-free polyolefin composition that satisfies the moisture content described above. Specific examples of the pressure atmosphere when kneading the polyolefin and magnesium sulfate anhydride include −65 Kpa or less, preferably −75 Kpa or less, and more preferably −85 Kpa or less. By heating and kneading in such a pressure atmosphere, the water content of the polyolefin and magnesium sulfate anhydride can be removed, and during the heating and kneading, especially the magnesium sulfate anhydride itself, which is a hygroscopic inorganic material, is removed. It is possible to suppress the moisture that is evaporated by heating, and the evaporation moisture causes secondary agglomeration of the hygroscopic inorganic material itself to cause poor dispersion. The temperature condition and time for kneading the polyolefin and magnesium sulfate anhydride may be set as appropriate according to the pressure atmosphere, the amount charged, etc., so as to satisfy the moisture content described above. Is usually 130 to 250 ° C., preferably 150 to 230 ° C., more preferably 170 to 210 ° C. The kneading of the polyolefin and the magnesium sulfate anhydride can be performed using a twin-screw kneading extruder having a pressure reducing function. The polyolefin and magnesium sulfate anhydride may be supplied to the raw material hopper of the twin-screw kneading extruder using a premixed material using a general mixer, and each of them may be supplied quantitatively to the raw material hopper. It may be done by doing. In this case, it is desirable that the raw material hopper should not absorb moisture of polyolefin and magnesium sulfate anhydride by nitrogen purge or the like.

The moisture content of the additive-free polyolefin composition is set to 0.1% by weight or less. By satisfying such a moisture content, an additive-free polyolefin composition that improves dispersibility of magnesium sulfate anhydride and has excellent hygroscopicity and moldability even if it contains no additives other than magnesium sulfate anhydride. It becomes possible to obtain. From the viewpoint of further improving the dispersibility and moldability of magnesium sulfate anhydride, the water content in the additive-free polyolefin composition is preferably 0 to 0.1% by weight, more preferably 0 to 0.09% by weight. Here, the moisture content means a value measured by a Karl Fischer moisture meter automatic moisture measuring device using a vaporizer (250 ° C.).

<Filling sodium chloride into the container and relative humidity in the container>
In the sodium chloride contained in the container of the present invention, the container is filled with sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more, and the relative humidity in the container is kept from when the container is sealed until it is opened. Set to maintain below 55%. Thus, it becomes possible to prevent solidification of sodium chloride by controlling the relative humidity in the container within a predetermined range from the time of sealing until it is opened. Here, “maintaining the relative humidity in the container at 55% or less” means that the relative humidity to which sodium chloride is exposed is 55% or less from the time the container containing sodium chloride is sealed until the container is opened at the time of use. Means holding. That is, sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more has a relative humidity of more than 55%, even if it is designed to remove the water in the container using any method. In the present invention, when exposed to the atmosphere, solidification occurs. Therefore, in the present invention, the sodium chloride having a purity of 99.5% by weight or more and an average particle size of 150 μm or more is sealed from when sealed to the container until the container is opened at the time of use. It is necessary to maintain the relative humidity to which sodium chloride is exposed at 55% or less.

The relative humidity in the container containing sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is maintained at 50% or less from the viewpoint of more effectively preventing the solidification of sodium chloride. It is preferable. Moreover, the lower limit value of the relative humidity in the container is not limited. By maintaining such a range of relative humidity, the present invention can utilize the moisture absorption characteristics of sodium chloride adjusted to the above-mentioned predetermined conditions, even in an extremely low humidity environment that requires equipment costs. Solidification can be prevented.

In addition, the present inventors have found that the solidification of sodium chloride proceeds when the relative humidity exceeds 55% even temporarily, as a new finding that has not existed before. Normally, it is assumed that products are exposed to temperature conditions of 4 ° C to 50 ° C in warehouses or transport trucks or ships that are not temperature controlled, but the relative humidity in the container is maintained below 55% in this temperature range. If possible, solidification can be prevented without using a desiccant excellent in hygroscopicity or a packaging material having a drying function without maintaining extremely low humidity.

In order to maintain the relative humidity in a container containing sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more, the purity is 99% in an atmosphere having a relative humidity of 55% or less, preferably 50% or less. The container may be filled with sodium chloride having an average particle diameter of 150 μm or more by 5 wt% or more. In order to achieve such relative humidity, it is desirable to set the temperature at the time of filling and sealing with sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more to 4 to 50 ° C. If the filling temperature is less than 4 ° C, sodium chloride may easily form dihydrate crystals, and if the filling temperature exceeds 50 ° C, the durability of the container may be affected. .

In the present invention, the amount of sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more filled in the container may be appropriately set according to the size and shape of the container, and usually 0.1 kg to 1 t. However, if a flexible container bag is used, it is usually about 150 kg to 1 t, and if a container other than the flexible container bag is used, it is usually about 0.1 kg to 50 kg.

The storage conditions of the sodium chloride in the container of the present invention are not particularly limited, but should be about 4 to 50 ° C. from the viewpoint of suppressing the decrease in the durability of the container and the formation of sodium chloride dihydrate crystals. Is preferred.

2. Sodium Chloride Storage Method According to the Present Invention, sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and is moisture-proof. The relative humidity in the conductive container is maintained at 55% or less.

In the storage method of the present invention, the sodium chloride used, the container, the relative humidity in the container, and the like are as described in the column “1. Sodium chloride in the container”.

Hereinafter, the present invention will be specifically described with reference to test examples and the like, but the present invention is not construed as being limited to these test examples. In the following test examples, the average particle diameter of sodium chloride is a value determined by an automatic dry sonic sieving measuring instrument (ROBOT SIFTER RPS-105M, manufactured by Seishin Enterprise Co., Ltd.). Further, the magnesium sulfate anhydride used in the reference examples shown below was measured with a laser diffraction / scattering particle size distribution analyzer (“Microtrack HRA particle size analyzer (model: 9320-X100), manufactured by Nikkiso Co., Ltd.)”. The average particle size is 3 to 7 μm and the water content is 0.5 to 2%.

Test example 1
(1) Preparation of sodium chloride Pharmaceutical sodium chloride (average particle size 316 μm) was transferred onto a vat, dried at 85 ° C. for 5 hours, dried at 130 ° C. for 10 hours, and then cooled to 85 ° C. Next, 3 kg of the obtained sodium chloride was filled into a polyethylene bag (inner bag) having a moisture permeability of about 6 g / m ² · 24 h and sealed by heat sealing, and this was further sealed with an aluminum foil laminated bag (outer bag) (layer structure: It was put in polyethylene terephthalate (PET) / aluminum foil (Al) / polyethylene (PE); moisture permeability 0 g / m ² · 24 h) and sealed by heat sealing, then stored at 20 ° C. for 1 day and cooled. Thus, the sodium chloride contained in the container had a purity of 99.9% by weight and a water content of 0% by weight.

(2) Setting and storage of sodium chloride storage conditions After storage at 20 ° C. for one day, the container is opened, and 0 ml, 0.03 ml, 0.06 ml, 0.15 ml and 0.3 ml of pure water are placed in the container. Mixed with sodium chloride, immediately transferred to a new polyethylene bag (inner bag), heat-sealed with a thermohygrometer (ondori TR-77Ui) inserted and sealed, and this was further laminated with an aluminum foil laminated bag ( Outer bag) (layer structure: three-layer structure of PET / Al / PE; moisture permeability 0 g / m ² · 24 h) and sealed. Thus, 0%, 0.001%, 0.002%, 0.005%, and 0.01% by weight of sodium chloride in the environment of 20 ° C. and 40% relative humidity respectively. Housed in a container. In addition, about the sodium chloride whose moisture content is 0.001 weight%, 0.002 weight%, and 0.005 weight%, it created by the method similar to the below-mentioned reference example 8 as a polyethylene bag used as an inner bag. Moisture-proof polyethylene container (three-layer film) in which hygroscopic inorganic material is kneaded (layer structure: PE layer 20 μm / PE layer 60 μm containing hygroscopic inorganic material / PE layer 20 μm three-layer structure; moisture permeability ^Two containers of about 2.5 g / m ² · 24 h) and an additive-free polyethylene container (layer structure: polyethylene 1 layer 80 μm; moisture permeability of about 6 g / m ² · 24 h) were used. For sodium chloride having a water content of 0% by weight, as an polyethylene bag used as an inner bag, an additive-free polyethylene container containing no hygroscopic inorganic material (layer structure: polyethylene one layer 80 μm; moisture permeability about 20 g / m ² · 24 h). Table 1 shows the conditions employed in this test example (water content of sodium chloride and types of inner bags used).

Thus, sodium chloride in a container was prepared and stored in a refrigerator set at 4 ° C. for 24 days. During storage, the relative humidity in the container was measured over time, the container was opened after storage, and the degree of solidification of sodium chloride was measured. The degree of solidification of sodium chloride is such that the stored sodium chloride is placed on an 8 mm grid (mesh: wire diameter 2 mm), passed through the grid, and the weight of sodium chloride remaining on the grid is measured. The weight of sodium chloride remaining on the lattice with respect to was calculated as the degree of solidification (%).

(3) Results The results of measuring the relative humidity in the container over time are shown in FIGS. 1 and 2, and the results of measuring the degree of solidification (%) are shown in Table 2. As is apparent from FIGS. 1, 2 and Table 2, when the relative humidity in the container always exceeds 55% during the storage period (conditions 1-2, 1-4, and 1-6), chlorination Sodium solidification occurred remarkably. In addition, even if the relative humidity in the container is 55% or less after 24 days of storage, even if the relative humidity in the container exceeds 55% during the storage period (Condition 1-5) Solidification of sodium chloride occurred. On the other hand, when the relative humidity in the container is constantly maintained at 55% or less from filling to storage (conditions 1-1 and 1-3), an aluminum foil laminated bag (outer bag) (layer structure: PET / Al / PE three-layer structure; moisture permeability of 0 g / m ² · 24 h) prevents the solidification of sodium chloride. In a moisture-proof polyethylene container in which a hygroscopic inorganic material has been kneaded, it is predicted that the hygroscopic inorganic material will function as a desiccant when an exterior formed of aluminum foil is used. Both 001% and 0.002% showed an effect of lowering the humidity. At 0.001%, solidification was suppressed, but at 0.002%, the relative humidity exceeded 55% and solidification occurred as in the case of the additive-free polyethylene. From the above results, it has become clear that solidification of sodium chloride can be prevented by maintaining the relative humidity in a container containing sodium chloride having a purity of 99.5% by weight or more at 55% or less.

Test example 2
(1) Preparation of Sodium Chloride Sodium chloride (purity 99.9% by weight, water content 0) contained in a container using sodium chloride for medical use (average particle size 316 μm) in the same manner as in Test Example 1 above. % By weight) was prepared.

(2) Setting and Storage of Sodium Chloride Storage Conditions The moisture content of sodium chloride and the type of inner bag are set to the conditions shown in Table 3, and the storage conditions are 24 at 25 ° C. (constant temperature and high humidity tank, relative humidity 60%). The test was conducted under the same conditions as in Test Example 1 except that the period was changed to days, and the relative humidity in the container and the solidification degree of sodium chloride after storage were measured over time.

(3) Results The results of measuring the relative humidity over time in the container are shown in FIGS. 3 and 4, and the results of measuring the degree of solidification (%) are shown in Table 4. Also from this result, when there was a storage period in which the relative humidity in the container exceeded 55% (Conditions 2-4, 2-6, 2-7), solidification of sodium chloride occurred, but storage from filling was started. In the case where the relative humidity in the container is constantly maintained at 55% or less throughout the period (conditions 2-1 to 2-3 and 2-5), an aluminum foil laminated bag (outer bag) (layer structure: PET / The moisture-proof container having a three-layer structure of Al / PE; moisture permeability 0 g / m ² · 24 h) was able to prevent solidification of sodium chloride. In addition, in the moisture-proof polyethylene container in which the hygroscopic inorganic material was kneaded as in Test Example 1, it is predicted that the hygroscopic inorganic material works as a desiccant when using an exterior formed of aluminum foil, The moisture content was 0.001%, 0.002%, 0.005%, and the humidity reduction effect was observed, and solidification was suppressed at 0.001% (Condition 2-3) and 0.002% (Condition 2-5). However, at 0.005%, like the additive-free polyethylene, the relative humidity exceeded 55% and solidification occurred.

Test example 3
(1) Preparation of Sodium Chloride Sodium chloride (purity 99.9% by weight, water content 0) contained in a container using sodium chloride for medical use (average particle size 316 μm) in the same manner as in Test Example 1 above. % By weight) was prepared.

(2) Setting and storage of sodium chloride storage conditions Except that the moisture content of sodium chloride and the type of inner bag were set to the conditions shown in Table 5, and the storage conditions were changed to 24 days at 50 ° C (dryer). The test was conducted under the same conditions as in Test Example 1, and the relative humidity in the container and the solidification degree of sodium chloride after storage were measured over time.

(3) Results The results of measuring the relative humidity over time in the container are shown in FIGS. 5 and 6, and the results of measuring the degree of solidification (%) are shown in Table 6. From these results, as in Test Examples 1 and 2, when there is a storage period in which the relative humidity in the container exceeds 55% (conditions 3-4 to 3-6), solidification of sodium chloride occurs. However, when the relative humidity in the container is always kept below 55% from filling to storage (conditions 3-1 to 3-3), the aluminum foil laminated bag (outer bag) (layer structure) It was confirmed that solidification of sodium chloride can be prevented by a moisture-proof container having a three-layer structure of PET / Al / PE; moisture permeability of 0 g / m ² · 24 h). In the moisture-proof polyethylene container in which the hygroscopic inorganic material was kneaded, when using an aluminum foil for the exterior, the hygroscopic inorganic material is predicted to work as a desiccant, and the moisture content is 0.002%, Humidity reduction effect was observed at 0.005%, and solidification was suppressed at 0.002%, but at 0.005%, the relative humidity exceeded 55% and solidification occurred as in the case of polyethylene without addition.

Test example 4
1000 kg of medical sodium chloride (average particle size: 313 μm, purity 99.9% by weight, water content: 0.02% by weight) was prepared by a method similar to that of an additive-free polyethylene inner bag or Reference Example 8 described later. Hygroscopic polyethylene container (inner bag) in which hygroscopic inorganic material is kneaded (layer structure: PE layer 20 μm / PE layer 60 μm containing hygroscopic inorganic material / PE layer 20 μm); 5 g / m ² · 24 h) and sealed, put in a flexible container bag, and stored for one month in a warehouse where temperature control is not performed. During the storage period, the temperature and relative humidity in the inner bag were measured over time. Further, after one month of storage, sodium chloride was discharged from the bottom of the flexible container bag, and the presence or absence of solidification of sodium chloride was confirmed.

7 and 8 show the results of measuring the temperature and relative humidity in the inner bag over time. FIG. 7 shows the result when an additive-free polyethylene inner bag is used, and FIG. 8 shows the result when a moisture-proof polyethylene inner bag into which a hygroscopic inorganic material is kneaded is used. At the time of filling, the temperature in the inner bag was about 45 ° C., but the temperature gradually decreased during the storage period and finally stabilized at about 30 ° C. In addition, when an additive-free polyethylene inner bag was used, the relative humidity inside the container gradually increased due to the influence of the humidity of the external environment, and eventually moved around 70%. In the case of using a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material was kneaded, the humidity effect from the external environment was prevented by the excellent moisture resistance, and the relative humidity was maintained at 55% or less.

In addition, when sodium chloride is taken out from the flexible container bag after storage, when an additive-free polyethylene inner bag is used (relative humidity is over 55%), there is a large lump of solidified sodium chloride that must be compressed from the outside. It was in a state that could be discharged somehow. On the other hand, when using a moisture-proof polyethylene inner bag in which a hygroscopic inorganic material is kneaded, the moisture permeability is 2.5 g / m ² · 24 h, which is higher than that of the aluminum foil barrier material. The relative humidity was maintained at 55% or less. As a result, no solidification was observed, and it was possible to discharge from the bottom only by gravity drop.

Test Example 5
(1) Preparation of sodium chloride Sodium chloride contained in a container (purity 99.9 wt%, water content 0 under the same conditions as in Test Example 1 except that sodium chloride (average particle size 167 μm) was used. % By weight) was prepared.

(2) Setting and Storage of Sodium Chloride Storage Conditions The moisture content of sodium chloride and the type of inner bag are set to the conditions shown in Table 7, and the storage conditions are 24 at 25 ° C. (constant temperature and high humidity tank, relative humidity 60%). The test was conducted under the same conditions as in Test Example 1 except that the period was changed to days, and the relative humidity in the container and the solidification degree of sodium chloride after storage were measured over time.

(3) Results FIG. 9 shows the results of measuring the relative humidity in the container over time, and Table 8 shows the results of measuring the degree of solidification (%). From this result, it was confirmed that solidification of sodium chloride could be prevented when the relative humidity in the container was constantly maintained at 55% or less during the storage period (conditions 5-1 and 5-2). The action of the moisture-proof polyethylene into which the hygroscopic inorganic material was kneaded was the same as in Test Example 2.

Test Example 6
(1) Preparation of sodium chloride Sodium chloride contained in a container (purity 99.9 wt%, moisture content 0 under the same conditions as in Test Example 1 except that sodium chloride (average particle size 27 μm) was used. % By weight) was prepared.

(2) Setting and Storage of Sodium Chloride Storage Conditions The sodium chloride moisture content and inner bag type are set to the conditions shown in Table 9, and the storage conditions are 25 ° C. (constant temperature and high humidity tank, relative humidity 60%). The test was conducted under the same conditions as in Test Example 1 except that the period was changed to days, and the relative humidity in the container and the solidification degree of sodium chloride after storage were measured over time.

(3) Results FIG. 10 shows the results of measuring the relative humidity in the container over time, and Table 10 shows the results of measuring the degree of solidification (%). Regardless of which container was used, solidification of sodium chloride occurred even though the relative humidity was maintained at 55% or less during the storage period. This is because the average particle size of the sodium chloride used was very fine at 27 μm, so the surface area and the contact area of sodium chloride were so large that it was easy to form a soft block-like lump, and it was difficult to pass through the 8 mm lattice in the solidification test. . Also, the presence or absence of hygroscopic inorganic materials was irrelevant.

Based on the above results, even for sodium chloride of about 3 to 1000 kg, sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is used, and the relative humidity in the container to be contained is 55% or less. It was confirmed that solidification can be prevented by maintaining the temperature.

Reference test example 1
1-1. Production of films containing hygroscopic layers
Reference example 1
Each of the raw materials shown below is a twin-screw kneading extruder (resin temperature during kneading is 160 to 210 ° C., vent pressure is −88 kPa, extrusion amount is 25 kg to 50 kg / h, and the raw material charging hopper is replaced with nitrogen) The mixture was kneaded and extruded by Twin Screw Extruder PCM-45 (manufactured by Ikekai Iron Works Co., Ltd.) to obtain a polyolefin composition containing additives in the form of pellets. Next, the obtained additive-containing polyolefin composition was subjected to extrusion molding with a T-die film molding machine (PLABOR GT-25-A, manufactured by Plastic Engineering Laboratory Co., Ltd.), thereby forming a single layer having a thickness of 60 μm. A film was obtained.
<Additive raw material for additive-containing polyolefin composition>
Polyethylene (LDPE; trade name “UBE polyethylene R300” (MFR0.35), manufactured by Ube Maruzen Polyethylene Co., Ltd.) 66.25% by weight
Magnesium sulfate anhydride 33% by weight
Dispersant (zinc stearate) 0.5% by weight
Antioxidant (trade name “Irganox 1010”, manufactured by BASF Japan Ltd.) 0.25% by weight

Reference example 2
Additive-free polyethylene (LDPE), the polyolefin composition prepared in Reference Example 1, and additive-free polyethylene (LDPE) are co-extruded in three layers using a three-layer three-layer inflation molding machine (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.). Thus, a resin layer (inner layer having a thickness of 20 μm) formed from additive-free polyethylene (LDPE), a moisture absorption layer (an intermediate layer having a thickness of 60 μm) formed from the polyolefin composition prepared in Reference Example 1, and an additive-free polyethylene ( A three-layer film in which resin layers (outer layers having a thickness of 20 μm) formed by (LDPE) were sequentially laminated was prepared.

1-2. Performance evaluation when used as a package of sodium chloride Using each of the films prepared above, a small bag of 15 cm in length and 20 cm in width was prepared by heat sealing. 500 g of Japanese Pharmacopoeia sodium chloride was put into this sachet, deaerated, and the inner bag and sodium chloride were brought into intimate contact and heat sealed. This was stored in a 60 ° C. dryer for 28 days. Seven days, 14 days, 21 days, and 28 days after storage, 500 g of sodium chloride in each sachet was dissolved in 2000 mL of purified water. Next, it was filtered using a membrane filter (diameter 47 mm, pore diameter 3 μm), and the filtration time and filtration pressure at this time were measured. Further, the membrane filter was dried after filtration, and the color difference was measured with a colorimetric color difference meter ZE2000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

Table 11 shows the obtained results. As shown in Table 11, both the single-layer film of Reference Example 1 and the three-layer film of Reference Example 2 have a filtration rate as slow as 3 minutes or more, and the coloration (color difference) of the filtration filter is remarkably recognized as 1 or more. It was. That is, from this result, it was confirmed that the additives (dispersant, antioxidant) contained in the film bleed out and mixed into the sodium chloride in the sachet, resulting in a decrease in quality.

Reference test example 2
A sachet (inner bag) made of an additive-free polyethylene film (thickness 80 μm) is covered with a sachet (outer bag) made of the three-layer film of Reference Example 2 (Package of Reference Structure 3) It was created. 500 g of Japanese Pharmacopoeia sodium chloride was put into the inner bag of the double structure package, and the inner bag was heat sealed. Next, the outer bag covering the inner bag was also heat sealed. The bleed out of the additive was evaluated under the same conditions as in Reference Test Example 1.

Table 12 shows the obtained results. From this result, even if an additive-free polyethylene film having a thickness of 80 μm is used as an inner bag, it cannot prevent the additive contained in the outer bag from being mixed into sodium chloride due to bleed-out. confirmed. Accordingly, it has been clarified that it is desirable that the polyolefin composition used for forming the moisture absorption layer of the package is substantially free of additives other than magnesium sulfate anhydride.

Reference test example 3
Using the raw materials shown below, the resin temperature during kneading is 160 to 210 ° C., the vent pressure is not reduced (Reference Example 4), −61 KPa (Reference Example 5), −76 KPa (Reference Example 6), or −88 KPa (Reference Example 7), the extrusion rate is 25 kg to 50 kg / h, and the raw material charging hopper is kneaded with a twin-screw kneading extruder (Twin Screw Extruder PCM-45, manufactured by Ikekai Iron Works Co., Ltd.) under nitrogen replacement conditions. By extruding, a pellet-shaped additive-free polyolefin composition was obtained. Next, the obtained additive-free polyolefin composition was extruded using a T-die film molding machine (PLABOR GT-25-A, manufactured by Plastic Engineering Laboratory Co., Ltd.), thereby forming a single layer film having a thickness of 60 μm. Got.
<Additive raw material of additive-free polyolefin composition>
Polyethylene (LDPE; trade name “UBE polyethylene F120N” (MFR1.2), manufactured by Ube Maruzen Polyethylene Co., Ltd.) 67% by weight
Magnesium sulfate anhydride 33% by weight

About the additive-free polyolefin composition obtained above, the moisture content was measured with a Karl Fischer moisture meter (250 ° C., 1 g, automatic moisture measuring device EV-200 (manufactured by Hiranuma Sangyo Co., Ltd.)). Further, the appearance of the monolayer film obtained above was observed with a microscope, and the number of aggregates of 100 μm or more present per 1 m ² was measured.

Table 13 shows the obtained results. From this result, when pressure reduction was not performed when kneading polyethylene and magnesium sulfate anhydride (Reference Example 4), the water content exceeded 0.15% by weight, and the dispersibility of magnesium sulfate anhydride was very poor. The single-layer film was found to have many aggregates, many perforations were observed, and the moldability was poor. On the other hand, when kneading polyethylene and magnesium sulfate anhydride under reduced pressure (Reference Examples 5 to 7), the water content was 0.1% by weight or less, and the dispersibility of magnesium sulfate anhydride was good. Thus, it was clarified that the generation of aggregates in the single-layer film can be suppressed, there is no perforation, and the moldability is good. In particular, in the polyolefin compositions (Reference Examples 6 and 7) in which kneading of polyethylene and magnesium sulfate anhydride was performed at −76 KPa or less, the generation of aggregates could be remarkably suppressed.

From the above results, in the case of obtaining a polyolefin composition without adding additives other than magnesium sulfate anhydride, there is no problem in dispersibility if the water content is 0.1% by weight or less. It turns out that things can be created. Further, it has been found that the pressure atmosphere in the kneader may be reduced to about −65 KPa or less as the means. And it became clear that the contamination of sodium chloride by the bleed-out of the additive can be suppressed by containing sodium chloride in a container using a molded body molded using the additive-free polyolefin composition thus produced. It was.

Reference test example 4
4-1. Production of polyolefin compositions and films
Reference Example 8
Using the raw materials shown below, they were kneaded with a twin-screw kneading extruder (Twin Screw Extruder PCM-45, manufactured by Ikekai Iron Works Co., Ltd.) under the same conditions as in Reference Test Example 3 (pressure atmosphere of -88 KPa). By extruding, 200 kg of pellet-shaped additive-free polyolefin composition was obtained. Next, the additive-free polyethylene (LDPE), the additive-free polyolefin composition obtained above, and the additive-free polyethylene (LDPE) are three-layered using a three-layer three-layer inflation molding machine (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.). A resin layer (inner layer with a thickness of 20 μm) formed from additive-free polyethylene (LDPE) by coextrusion, a moisture absorption layer (an intermediate layer with a thickness of 60 μm) formed from the polyolefin composition, and an additive-free polyethylene (LDPE) A three-layer film in which the resin layers (outer layers having a thickness of 20 μm) formed in step 1 were sequentially laminated was prepared.
<Raw material composition of additive-free polyolefin composition>
Polyethylene (LDPE; trade name “UBE polyethylene R300” (MFR0.35), manufactured by Ube Maruzen Polyethylene Co., Ltd.) 67% by weight
Magnesium sulfate anhydride 33% by weight

Reference Example 9
Additive-free polyethylene (LDPE), additive-free polyolefin composition obtained in Reference Example 8 and additive-free polyethylene (LLDPE) were added to a 3 type 3 layer inflation molding machine (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.). By layer coextrusion, a resin layer (inner layer with a thickness of 20 μm) formed of additive-free polyethylene (LDPE), a moisture absorption layer (an intermediate layer with a thickness of 60 μm) formed of the polyolefin composition of Reference Example 8, and an additive-free layer A three-layer film in which resin layers (outer layers having a thickness of 20 μm) formed of polyethylene (LLDPE) were sequentially laminated was prepared.

Reference Example 10
By using the raw materials shown below and kneading and extruding under the same conditions as in Reference Test Example 3 (pressure atmosphere of -88 KPa) with a twin-screw kneading extruder (PCM-80 manufactured by Ikegai Iron Works Co., Ltd.) A pellet-shaped additive-free polyolefin composition was obtained. Subsequently, additive-free polyethylene (LDPE), the additive-free polyolefin composition obtained above, and additive-free polyethylene (LLDPE) are coextruded in three layers with an air-cooled inflation multilayer film forming apparatus (Placo Corporation). Thus, a resin layer (inner layer with a thickness of 20 μm) formed of additive-free polyethylene (LDPE), a moisture absorption layer (an intermediate layer of thickness of 60 μm) formed with the polyolefin composition, and an additive-free polyethylene (LLDPE) were formed. A three-layer film in which a resin layer (an outer layer having a thickness of 20 μm) was sequentially laminated was prepared.
<Raw material composition of additive-free polyolefin composition>
Polyethylene (LDPE; trade name “UBE polyethylene F120N (MFR1.2)”, manufactured by Ube Maruzen Polyethylene Co., Ltd.) 67% by weight
Magnesium sulfate anhydride 33% by weight

4-2. Moisture content of the polyolefin composition, film appearance and performance evaluation when used as a package of sodium chloride The appearance of each of the three-layer films obtained in Reference Examples 8 to 10 was observed with a microscope. Generation | occurrence | production of the thing was fully suppressed and it was confirmed that the magnesium sulfate anhydride can be disperse | distributed favorably.

Table 14 shows the results of measuring the water content of the additive-free polyolefin compositions obtained in Reference Example 8 (same as Reference Example 9) and 10 by the same method as in Reference Test Example 3. As a result, all of the additive-free polyolefin compositions obtained in Reference Examples 8 and 10 had a water content of 0.1% by weight or less. That is, also from this test result, when obtaining a polyolefin composition without adding additives other than magnesium sulfate anhydride, by kneading so that the water content is 0.1% by weight or less, magnesium sulfate is obtained. It was confirmed that the anhydride was excellent in dispersibility and the moldability was good.

Furthermore, using the three-layer films obtained in Reference Examples 8 to 10, the additive bleed-out was evaluated under the same conditions as in Reference Test Example 1. The results obtained are shown in Table 15. From these results, it was found that all the three-layer films had a sufficiently short filtration time and maintained a low color difference, and were able to prevent adverse effects on the contained sodium chloride.

Claims (31)

1. Sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity in the moisture-proof container is 55% or less. Sodium chloride in a container, which is maintained and free from solidification of sodium chloride.
2. The sodium chloride in a container according to claim 1, wherein the sodium chloride is not in direct contact with the hygroscopic material contained in the moisture-proof container.
3. The sodium chloride in a container according to claim 1 or 2, wherein the relative humidity in the moisture-proof container is maintained at 50% or less.
4. The sodium chloride in a container according to any one of claims 1 to 3, wherein the sodium chloride has an average particle diameter of 150 to 700 µm.
5. The sodium chloride in a container according to any one of claims 1 to 4, wherein 0.1 kg to 1 t of sodium chloride is contained in a moisture-proof container.
6. The sodium chloride in a container according to any one of claims 1 to 5, wherein the water content of sodium chloride is 0.002% by weight or less.
7. The sodium chloride in a container according to any one of claims 1 to 6, wherein the moisture permeability of the moisture-proof container is 0.5 g / m ² · 24 h or less.
8. The sodium chloride in a container according to any one of claims 1 to 7, wherein the moisture-proof container is a polyolefin moisture-proof container having a moisture-absorbing layer made of polyolefin containing a hygroscopic inorganic material.
9. The sodium chloride in a container according to claim 8, wherein the hygroscopic inorganic material is magnesium sulfate anhydride and / or zeolite.
10. 10. The polyolefin moisture-proof container is formed of a laminate in which a resin layer having no additive is laminated on both surfaces of a moisture-absorbing layer made of a polyolefin kneaded with a hygroscopic inorganic material. Sodium chloride in a container.
11. The sodium chloride in a container according to claim 10, wherein the laminate is in the form of a film or a sheet.
12. The sodium chloride in a container according to any one of claims 8 to 11, wherein the hygroscopic layer is substantially free of additives other than the hygroscopic material.
13. The sodium chloride in a container according to any one of claims 1 to 12, wherein the purity of the sodium chloride is 99.9% by weight or more.
14. The sodium chloride in a container according to any one of claims 1 to 13, wherein 0.1 to 50 kg of sodium chloride is contained in the container.
15. The sodium chloride in a container according to any one of claims 1 to 14, which is used as a raw material for a powder dialysis agent.
16. Sodium chloride having a purity of 99.5% by weight or more and an average particle diameter of 150 μm or more is contained in a moisture-proof container having a moisture permeability of less than 3 g / m ² · 24 h, and the relative humidity in the moisture-proof container is maintained at 55% or less. A method for preserving sodium chloride, characterized in that
17. The method for preserving sodium chloride according to claim 16, wherein the sodium chloride is not in direct contact with a hygroscopic material contained as a constituent material of the moisture-proof container.
18. The method for preserving sodium chloride according to claim 16 or 17, wherein the relative humidity in the container is maintained at 50% or less.
19. The method for preserving sodium chloride according to any one of claims 16 to 18, wherein the average particle diameter of the sodium chloride is 150 to 700 µm.
20. The method for preserving sodium chloride according to any one of claims 16 to 19, wherein 0.1 kg to 1 t of sodium chloride is contained in a container.
21. The method for preserving sodium chloride according to any one of claims 16 to 20, wherein the product temperature during filling and storage is maintained at 4 ° C or higher and 50 ° C or lower.
22. The method for preserving sodium chloride according to any one of claims 16 to 21, wherein the water content of the sodium chloride is 0.002% by weight or less.
23. The method for preserving sodium chloride according to any one of claims 16 to 22, wherein the moisture permeability of the moisture-proof container is 0.5 g / m ² · 24 h or less.
24. The method for preserving sodium chloride according to any one of claims 16 to 23, wherein the moisture-proof container is a polyolefin moisture-proof container having a moisture-absorbing layer made of polyolefin containing a hygroscopic inorganic material.
25. The method for preserving sodium chloride according to claim 24, wherein the hygroscopic inorganic material is magnesium sulfate anhydride and / or zeolite.
26. The polyolefin moisture-proof container is formed of a laminate in which a resin layer having no additive is laminated on both surfaces of a moisture-absorbing layer made of polyolefin into which a hygroscopic inorganic material is kneaded. Storage method of sodium chloride.
27. The method for preserving sodium chloride according to claim 26, wherein the laminate is in the form of a film or a sheet.
28. The method for preserving sodium chloride according to any one of claims 24 to 27, wherein the hygroscopic layer substantially does not contain additives other than the hygroscopic material.
29. The method for preserving sodium chloride according to any one of claims 16 to 28, wherein the purity of the sodium chloride is 99.9% by weight or more.
30. The method for preserving sodium chloride in a container according to any one of claims 16 to 29, wherein 0.1 to 50 kg of sodium chloride is accommodated in a moisture-proof container.
31. The method for preserving sodium chloride according to any one of claims 16 to 30, which is a method for preserving sodium chloride used as a raw material for a powder dialysis agent.

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